MULTISPEED ALTERNATING CURRENT MOTOR
A system is for a machine having an alternating current (AC) power source with a first side and a second side, one or more windings, an AC polarity detector, a Hall effect device, two or more pairs of power switches, and a motor controller. The motor controller determines which of the power switches to open or close to obtain a direction of current flow through the one or more windings based on signals from the AC polarity detector and the Hall effect device.
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This application is a continuation of U.S. application Ser. No. 16/664,550, filed Oct. 25, 2019, entitled Multispeed Alternating Current Motor, which is a continuation of U.S. application Ser. No. 15/940,956, filed Mar. 29, 2018, entitled Multispeed Alternating Current Motor, now U.S. Pat. No. 10,461,671, issued Oct. 29, 2019, which takes priority to U.S. App. No. 62/478,588, filed Mar. 29, 2017, and entitled Multispeed Alternating Current Motor, the entire contents of which are incorporated herein by reference.
FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTNot Applicable.
COMPACT DISK APPENDIXNot Applicable.
BACKGROUNDIn view of the growing proliferation of environmentally friendly laws, enhancements to various classes of motors are required. For example, refrigeration fan motors in a low wattage range, e.g. 4 to 16 watts, used in both the commercial and residential refrigeration markets, have traditionally been low efficiency, such as around 12%-26% efficient. It would be desirable to provide technologies to address enhancements required in different classes of motors.
SUMMARYIn one aspect, a multispeed alternating current (AC) machine circuit is for an AC power source having a first side and a second side. The AC machine circuit includes two or more pairs of power switches, one or more windings, and a control circuit to close one pair of power switches to cause current to flow from a first side of the AC power source, through the one or more windings, to the second side of the AC power source and to close the other pair of power switches to cause current to flow from the second side of the AC power source, through the one or more windings, to the first side of the AC power source.
In another aspect, a circuit is for a machine having alternating current (AC) power source having a first side (L1) and a second side (L2). The circuit comprises a winding with a start side and an end side, a first power switch connected between the first side and the winding start side, a second power switch connected between the second side and the winding start side, a third power switch connected between the first side and the winding end side, a fourth power switch connected between the second side and the winding end side, and a control circuit. The control circuit closes the first power switch and the fourth power switch and open the second power switch and the third power switch to cause current to flow from the first side to the second side or closes the second power switch and the third power switch and open the first power switch and the fourth power switch to cause current to flow from the second side to the first side.
In another aspect, a circuit is for a machine having alternating current (AC) power source having a first side (L1) and a second side (L2). The circuit comprises a first winding with a first start side and a first end side, a second winding with a second start side and a second end side, a first power switch connected between the AC power source first side and the first winding start side, a second power switch connected between the AC power source second side and the first winding start side, a third power switch connected between the AC power source first side and the first winding end side, a fourth power switch connected between the AC power source second side and the first winding end side, a fifth power switch connected between the AC power source first side and the second winding end side, a sixth power switch connected between the AC power source second side and the second winding end side, and a control circuit. The control circuit closes the first power switch and the sixth power switch and open the second power switch, the third power switch, the fourth power switch, and the fifth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the third power switch and the fourth power switch and open the first power switch, the second power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the first power switch and the fifth power switch and open the second power switch, the third power switch, the fourth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation or closes the second power switch and the fourth power switch and open the first power switch, the third power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation.
In another aspect, a method is for a multispeed alternating current (AC) machine circuit for an AC power source having a first side and a second side. The method includes providing two or more pairs of power switches, providing one or more windings, and providing a control circuit to close one pair of power switches to cause current to flow from a first side of the AC power source, through the one or more windings, to the second side of the AC power source and to close the other pair of power switches to cause current to flow from the second side of the AC power source, through the one or more windings, to the first side of the AC power source. The method further includes providing components for the control circuit described herein and operating the circuit as described herein.
In another aspect, a method is for a circuit for a machine having alternating current (AC) power source having a first side (L1) and a second side (L2). The method comprises providing a winding with a start side and an end side, providing a first power switch connected between the first side and the winding start side, providing a second power switch connected between the second side and the winding start side, providing a third power switch connected between the first side and the winding end side, providing a fourth power switch connected between the second side and the winding end side, and providing a control circuit. The control circuit closes the first power switch and the fourth power switch and open the second power switch and the third power switch to cause current to flow from the first side to the second side or closes the second power switch and the third power switch and open the first power switch and the fourth power switch to cause current to flow from the second side to the first side. The method further includes providing components for the control circuit described herein and operating the circuit as described herein.
In another aspect, a method is for a circuit for a machine having alternating current (AC) power source having a first side (L1) and a second side (L2). The method comprises providing a first winding with a first start side and a first end side, providing a second winding with a second start side and a second end side, providing a first power switch connected between the AC power source first side and the first winding start side, providing a second power switch connected between the AC power source second side and the first winding start side, providing a third power switch connected between the AC power source first side and the first winding end side, providing a fourth power switch connected between the AC power source second side and the first winding end side, providing a fifth power switch connected between the AC power source first side and the second winding end side, providing a sixth power switch connected between the AC power source second side and the second winding end side, and providing a control circuit. The control circuit closes the first power switch and the sixth power switch and open the second power switch, the third power switch, the fourth power switch, and the fifth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the third power switch and the fourth power switch and open the first power switch, the second power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the first power switch and the fifth power switch and open the second power switch, the third power switch, the fourth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation or closes the second power switch and the fourth power switch and open the first power switch, the third power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation. The method further includes providing components for the control circuit described herein and operating the circuit as described herein.
In another aspect, a divided phase windings circuit includes motor divided phase windings, a power switch circuit comprising at least one power switch and a direct current (DC) supply circuit all at a midpoint of the divided motor phase windings, and a non-collapsing DC power supply component to prevent the DC power supply from collapsing when the at least one power switch is on and conducting. The non-collapsing DC power supply component may include, for example, one or more of a tap from the motor divided phase windings electrically connected to the DC power supply, a secondary phase coil winding connected to the DC power supply to power the power supply, one or more resistors between the divided phase windings and the power switch circuit, one or more Zener diodes between the divided phase windings and the power switch circuit, and/or an electrical component to create a voltage drop between the motor divided phase windings and the power switch circuit to prevent the power supply from collapsing when the at least one power switch in the power switch circuit is on and conducting.
In one example, a phase windings circuit for a motor includes at least two phase windings forming one half of motor phase windings of the circuit and at least two other phase windings forming another half of the motor phase windings of the circuit. A direct current (DC) power supply is located at least approximately at a midpoint of the motor phase windings to receive alternating current (AC) power transferred from one or more of the phase windings and convert the AC power to DC power. A first stage power switch circuit comprises at least one power switch outside of the DC power supply and is electrically connected at least approximately at a midpoint between phase windings on each half of the circuit. A second stage power switch circuit comprises at least one other power switch outside of the DC power supply and is electrically connected at least approximately at the midpoint of the divided phase windings to receive AC power from the motor divided phase windings. A non-collapsing DC power supply component prevents the DC power supply from collapsing when the at least one power switch or the at least one other power switch is on and conducting.
In another example, a circuit for a motor comprises at least two phase windings forming one half of motor phase windings of the circuit and at least two other phase windings forming another half of the motor phase windings of the circuit. A direct current (DC) power supply at least approximately at a midpoint of the motor phase windings receives alternating current (AC) power transferred from one or more of the phase windings and converts the AC power to DC power. A first stage power switch circuit comprises at least one power switch outside of the DC power supply and is electrically connected at least approximately at a midpoint between the at least two of the phase windings on each half of the circuit. A second stage power switch circuit comprises at least one other power switch outside of the DC power supply and is electrically connected at least approximately at the midpoint of the phase windings to receive AC power from the motor phase windings. A motor controller controls the first stage power switch circuit and the second stage power switch circuit. The motor controller is electrically connected at at least one of (i) at least approximately at the midpoint of the phase windings and (ii) at least approximately at the midpoint between the at least two of the phase windings on each half of the circuit. A non-collapsing DC power supply component is connected to the DC power supply to prevent the DC power supply from collapsing when the at least one power switch or the at least one other power switch is on and conducting.
In another example, a motor has multiple motor phases (i.e. motor phase windings) and a supply line voltage through the phases. The motor phases are divided into four parts (fourths or quarters), with two motor phase windings forming one half of the motor phase windings of the circuit and two other motor phase windings forming the other half of the motor phase windings of the circuit. The motor controller for the motor and the power electronics for the motor are placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided phases and/or at a midpoint or center between two of the divided motor phases on each half of the circuit (e.g. “quarter-point”). The direct current (DC) power supply (e.g. for the electronics used in the motor controller) are also located between the divided phases, between the two halves of the divided phases and/or at a midpoint or center between two of the divided motor phases on each half of the circuit. The motor phases provide current limiting and the voltage drop from the line voltage supply lines to low voltage DC to the DC power supply, thereby reducing the DC power supply component count and allowing for the use of low voltage components for the DC power supply and for the motor controller.
In another example, the motor phases are divided into four parts (fourths or quarters), with two motor phase windings forming one half of the motor phase windings of the circuit and two other motor phase windings forming the other half of the motor phase windings of the circuit. The motor controller for the motor has two stages, with a first stage of the motor controller placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided motor phase windings, and a second stage of the motor controller placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided motor phase windings. The power electronics for the motor have two stages, with a first stage of the power electronics placed at a midpoint or center between two of the divided motor phase windings on each half of the motor phase windings (e.g. “quarter-point”) and a second stage of the power electronics also placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided motor phase windings. The direct current (DC) power supply (e.g. for the electronics used in the motor controller) are also located between the divided motor phase windings, between the two halves of the divided motor phase windings and/or at a midpoint or center between two of the divided motor phase windings on each half of the motor phase windings.
In another aspect, a method is for a machine having an alternating current (AC) power source with a first side (L1) and a second side (L2). The method comprises: at a motor controller for a circuit comprising a winding with a start side and an end side, a first power switch connected between the first side and the winding start side, a second power switch connected between the second side and the winding start side, a third power switch connected between the first side and the winding end side, and a fourth power switch connected between the second side and the winding end side: receiving a signal from an AC polarity detector and another signal from a Hall effect device and determining which of the power switches to open or close to obtain a proper direction of current flow through the winding based on the signal and the other signal. The motor controller closes the first power switch and the fourth power switch and opens the second power switch and the third power switch to cause current to flow from the first side to the second side or closes the second power switch and the third power switch and opens the first power switch and the fourth power switch to cause current to flow from the second side to the first side.
In another aspect, a method is for a machine having an alternating current (AC) power source having a first side (L1) and a second side (L2). The method comprises: at a control circuit for a circuit comprising a first winding with a first start side and a first end side, a second winding with a second start side and a second end side, a first power switch connected between the AC power source first side and the first winding start side, a second power switch connected between the AC power source second side and the first winding start side, a third power switch connected between the AC power source first side and the first winding end side, a fourth power switch connected between the AC power source second side and the first winding end side, a fifth power switch connected between the AC power source first side and the second winding end side, and a sixth power switch connected between the AC power source second side and the second winding end side: closing the first power switch and the sixth power switch and opening the second power switch, the third power switch, the fourth power switch, and the fifth power switch to cause current to flow through the first winding and the second winding for fractional speed operation. The control circuit closes the third power switch and the fourth power switch and opens the first power switch, the second power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding and the second winding for fractional speed operation. The control circuit closes the first power switch and the fifth power switch and opens the second power switch, the third power switch, the fourth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation. The control circuit closes the second power switch and the fourth power switch and opens the first power switch, the third power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation.
In another aspect, a method is for a machine having an alternating current (AC) power source with a first side (L1) and a second side (L2), two or more pairs of power switches, and one or more windings. The method comprises closing one pair of power switches by a control circuit to cause current to flow from a first side of the AC power source, through the one or more windings, and to the second side of the AC power source and closing another pair of power switches by the control circuit to cause current to flow from the second side of the AC power source, through the one or more windings, and to the first side of the AC power source.
In another aspect, a circuit is for a machine having an alternating current (AC) power source having a first side (L1) and a second side (L2). The circuit comprises a winding with a start side and an end side, a first power switch connected between the first side and the winding start side, a second power switch connected between the first side and the winding end side, a third power switch connected between the second side and the winding start side, a fourth power switch connected between the second side and the winding end side, an AC polarity detector to detect whether voltage from the AC power source is higher at the first side of the AC power source or the second side of the AC power source and output a signal indicating whether the voltage is higher at the first side of the AC power source or the second side of the AC power source, and a Hall effect device to detect a position of a rotor of the machine relative to a stator of the machine and output another signal indicating the position of the rotor relative to the stator. A motor controller receives the signal from the AC polarity detector and the other signal from the Hall effect device and determines which of the power switches to open or close to obtain a direction of current flow through the winding based on the signal and the other signal. In one aspect, the motor controller closes the first power switch and the fourth power switch and opens the second power switch and the third power switch to cause current to flow from the first side to the second side or closes the second power switch and the third power switch and opens the first power switch and the fourth power switch to cause current to flow from the second side to the first side.
In another aspect, a circuit is for a machine having an alternating current (AC) power source having a first side (L1) and a second side (L2). The circuit comprises a first winding with a first start side and a first end side, a second winding with a second start side and a second end side, wherein the second winding start side is connected to the first winding end side, a first power switch connected between the AC power source first side and the first winding start side, a second power switch connected between the AC power source first side and the first winding end side, a third power switch connected between the AC power source first side and the second winding end side, a fourth power switch connected between the AC power source second side and the first winding start side, a fifth power switch connected between the AC power source second side and the first winding end side, and a sixth power switch connected between the second side and the second winding end side. The circuit has a motor controller to control opening and closing the power switches to cause current to flow through the first winding and the second winding for fractional speed operation and to cause current to flow through the first winding and not the second winding for full speed operation, the motor controller further to close the first power switch and the sixth power switch and open the second power switch, the third power switch, the fourth power switch, and the fifth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or close the third power switch and the fourth power switch and open the first power switch, the second power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or close the first power switch and the fifth power switch and open the second power switch, the third power switch, the fourth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation or close the second power switch and the fourth power switch and open the first power switch, the third power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation.
New and useful circuits are disclosed that provide advantages over the prior art for controlling synchronous brushless permanent magnet motors. One embodiment of the present disclosure includes one or more circuits for an electronically commutated motor (ECM). Another embodiment of the present disclosure includes one or more circuits for a shaded pole motor. Another embodiment of the present disclosure includes one or more circuits for other types of motors.
In one aspect, a motor has multiple motor phases (i.e. motor phase windings) and a supply line voltage through the phases. The motor phases are divided in half and both the motor controller for the motor and the power electronics for the motor are placed at a “mid-point” or “center point” in the supply line voltage between the divided phases. The direct current (DC) power supply (e.g. for the electronics used in the motor controller) are also located between the divided phases. The motor phases provide current limiting and the voltage drop from the line voltage supply lines to low voltage DC to the DC power supply, thereby reducing the DC power supply component count and allowing for the use of low voltage components for the DC power supply and for the motor controller.
Prior systems used a Zener diode or other voltage regulator located in series with a power switch and the motor phases, which limited the maximum power of the motor to the maximum wattage value of the Zener diode. Circuits in the present disclosure eliminate the Zener diode voltage regulator from the primary current path for the motor phases so that a Zener diode voltage regulator is not located in series with a power switch and the motor phases, which eliminates the need to lower the wattage specification otherwise needed for a Zener diode. Instead, the Zener diode or other voltage regulator is located in parallel with the power switch(es) in some embodiments of the present disclosure.
In another aspect, a motor has multiple motor phases (i.e. motor phase windings) and a supply line voltage through the motor phases. The motor phases are divided into four parts (fourths or quarters), with two motor phase windings forming one half of the motor phase windings of the circuit and two other motor phase windings forming the other half of the motor phase windings of the circuit. The motor controller for the motor and the power electronics for the motor are placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided phases and/or at a midpoint or center between two of the divided motor phases on each half of the circuit. The direct current (DC) power supply (e.g. for the electronics used in the motor controller) are also located between the divided phases, between the two halves of the divided phases and/or at a midpoint or center between two of the divided motor phases on each half of the circuit. The motor phases provide current limiting and the voltage drop from the line voltage supply lines to low voltage DC to the DC power supply, thereby reducing the DC power supply component count and allowing for the use of low voltage components for the DC power supply and for the motor controller.
In one example, the motor phases are divided into four parts (fourths or quarters), with two motor phase windings forming one half of the motor phase windings of the circuit and two other motor phase windings forming the other half of the motor phase windings of the circuit. The motor controller for the motor has two stages, with a first stage of the motor controller placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided motor phase windings, and a second stage of the motor controller placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided motor phase windings. The power electronics for the motor have two stages, with a first stage of the power electronics placed at a midpoint or center between two of the divided motor phase windings on each half of the motor phase windings (i.e. “quarter-point”) and a second stage of the power electronics also placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided motor phase windings. The direct current (DC) power supply (e.g. for the electronics used in the motor controller) is also located between the divided motor phase windings, between the two halves of the divided motor phase windings and/or at a midpoint or center between two of the divided motor phase windings on each half of the motor phase windings.
For example, the DC power supply is located with the first stage when the DC power supply powers the first stage motor controller at the “quarter-point.” However, the DC power supply conceptually may be considered to be at a “mid-point” of the motor phase windings because when the first stage (stage 1) power electronics are energized and the second stage (stage 2) power electronics are not energized, the DC power supply is in the middle of the active coils (active motor phase windings) and the other two motor phase windings (coils) are not active at that time. The two active coils are current limiting. When the second stage is energized while the first stage is energized, the first stage coils are in parallel with the coils in the second stage.
Circuits in the present disclosure eliminate the need for an opto-isolator to allow switching between sensing/control electronics of a motor controller and a power switch of the motor controller. Prior systems had two neutral reference values, one for sensing/control electronics and one for a power switch.
Circuits in the present disclosure have improved line phase angle detection, eliminating the need for a precision resistance bridge linked to the input of an opto-isolator. Thus, the circuits of this aspect have more accurate line phase angle detection.
Circuits in the present disclosure reduce different electrical neutral values for the power switches and motor controller to one value. This guarantees that the power switch(s) of the circuits with this aspect will reliably transition from completely “off” to fully saturated.
Prior systems that included two switches have a difficult time turning one switch off completely for one half of an AC cycle. Circuits in the present disclosure place one or more switches outside of a DC power supply and motor controller circuit, resulting in proper switching.
Each of these improvements not only increases the reliability of the operation of the motor controller, but also serves to improve the combined motor/motor controller efficiency.
The divided phase winding circuits in the present disclosure can be used in a variety of motors, such as DC brushless motors/electronically communicated motors (ECMs), shaded pole motors, other synchronous motors, permanent-split capacitor (PSC) motors, etc.
For example,
The motor 102 can operate below, at, or above synchronous speeds. This is due to the fact that fractions of half cycles can flow through the phase windings.
The divided phase winding circuit of
The divided phase windings 104, 106 can be bifilar or lap wound. The alternating current power source has its lead L1 connected to the start side S1 of the first winding 104. The other end of the winding 104, labeled F1, is connected to one of the inputs of the control circuit 108. The other input side of the control circuit 108 is attached to the start side S2 of the second divided phase winding 106, and the finish side of the same divided phase winding, labeled F2, is attached to the input lead L2 of the AC power source.
As another example,
The divided phase winding circuit 302 of
The DC power supply 310 converts the low voltage AC power received from the divided phase windings 304, 306 to a DC voltage configured to power the DC powered components of the divided phase winding circuit, including the motor controller 308. The DC power supply 310 then supplies power to the motor controller 308.
The motor controller 308 controls the start-up and operation of the divided phase winding circuit 302. For example, the motor controller 308 controls start-up, including where the motor is a synchronous motor. The motor controller 308 determines the location of the rotor relative to the stator. The motor controller 308 also determines and monitors the speed of the rotor, such as in revolutions per minute (RPMs), to determine operational parameters of the motor, such as when the motor has reached synchronous speed, and controls the motor based on the location of the rotor and/or speed of the motor. In one example, the motor controller 308 has a Hall effect switch and/or other rotation determining device to determine the position of the rotor and/or rotation counting or speed determining device to determine the speed of the rotor.
The power switch(es) circuit 312 includes one or more power switches, such as one or more metal-oxide-semiconductor field-effect transistors (MOSFETs), silicon-controlled rectifiers (SCRs), transistors, or other switches or switching devices. The one or more switches are on or off or one is on while the other is off. For example, in one half cycle of an AC cycle, a first power switch is on and conducting while the second switch is off and not conducting. In the other half cycle of the AC cycle, the second power switch is on and conducting while the first switch is off and not conducting. In circuits with one switch, the switch may be on and conducting or off and not conducting during one or more portions of the AC cycle.
The power switch(es) circuit 312 is isolated from (outside of) the DC power supply 310, which makes the divided phase winding circuit 302 more stable than circuits having the power switch(es) circuit within (and not isolated from) the DC power supply.
When the power switch(es) of a circuit turn on, there is only a slight voltage drop through the power switch(es) due to the minor resistance of the power switch(es). Therefore, if the input voltage for the DC power supply is developed by connecting the DC power supply leads to both sides of a power switch (or power switches), this would result in the DC power supply collapsing (i.e. the DC voltage from the DC power supply reducing to a voltage level at or below the switch ‘on’ resistance times the current through the power switch(es), which is close to zero) when the power switch is in an ‘on’ state or not being able to receive power and power the DC components of the circuit.
For example, if the power switch is directly connected across the DC power supply or across the DC side of a bridge rectifier and if there are not one or more components in series with the power switch to create a voltage drop when the power switch is conducting or ‘on’, the conducting power switch ‘shorts out’ or connects together the positive and negative terminals of the bridge rectifier for the DC power supply, which collapses the DC voltage (causes the DC voltage to be reduced to a level at or below the ‘on’ resistance of the power switch times the current through the power switch, which is close to zero). Since the ‘on’ resistance of the power switch is extremely low or typically in the milliohms, the DC voltage is very close to zero.
The divided phase winding circuit 302 includes one or more non-collapsing DC power supply components 316, 318 (components to prevent the DC voltage from the DC power supply from being reduced to or below the switch ‘on’ resistance times the current through the power switch(es), which is close to zero), including voltage drop components or direct DC power supply powering components to create a non-collapsing DC power supply. Examples of non-collapsing DC power supply components 316, 318 include a tap from the primary phase winding 304, 306 electrically connected to the DC power supply 310, a secondary phase coil winding connected to the DC power supply to power the power supply, resistors between the divided phase windings and the power switch(es) circuit 312, one or more Zener diodes between the divided phase windings and the power switch(es) circuit, a non-saturated semiconductor or other resistive component between the divided phase windings and the power switch(es) circuit 312 where the resistance is high enough to create a significant voltage drop and where this voltage drop causes the DC power supply when the switch is ‘on’, or other components to create a voltage drop between the primary divided phase windings and the power switch(es) circuit to prevent the DC power supply from collapsing when the power switch(es) in the power switch(es) circuit is/are on and conducting. The divided phase winding circuit 302 therefore provides a constant flow of power regardless of whether the power switch(es) circuit is on and conducting or off and not conducting.
Many electronically controlled synchronous motors have circuits that detect the zero crossing of the AC voltage applied to the phase windings. This zero crossing detection circuit sends a signal to the motor controller 308 to determine when the motor is at synchronous speed. If the AC supply voltage has electrical noise riding on, usually due to other equipment operating on the same circuit, this electrical noise can cause the zero crossing detector to operate incorrectly affecting the control of the motor, which normally appears as acoustical noise in the motor.
In one example, the divided phase winding circuit 302 is part of a synchronous motor. The synchronous motor receives line power (that is, AC power with a current and voltage) at L1 and L2. A synchronous motor using a divided phase winding using the associated circuit of the present disclosure does not rely upon detecting the zero crossing of the applied AC voltage to control the motor but rather detects the polarity of the voltage, i.e. whether the polarity L2 is higher or less than L1, allowing for quiet operation even when electrical noise is present in the AC supply.
The DC power supply 310 in
In some circuits, when the motor reaches synchronous speed, the one or more power switch(es) turn off and thereby cause the low voltage power to stop flowing to the motor controller. In one example, the path from one divided phase winding through the power switch(es) to another divided phase winding is shorted, such as at synchronous speed. This results in the DC power supply and motor controller no longer receiving the low power supply voltage from the phase windings, such as in the event there is no capacitor to hold a charge during the short or a capacitor that is present is not large enough to hold enough charge during the short. The circuit 402 of
In one example, a DC power supply 410 for a divided motor phase controller is formed by a Zener diode and a storage capacitor that receives power during a portion of an alternating current (AC) cycle when the power switch(es) are off. When the motor is operating at synchronous speed, the power switch(es) are continuously conducting. Therefore, the amount of voltage being supplied to the DC power supply is equal to the voltage drop across the switch(es), which can result in a low voltage when using low on resistance (RDS(on)) power MOSFETs.
In one example, the power switch(es) circuit 612 includes a Zener diode or other voltage regulator and a power switch in parallel. Whereas, prior systems included the power circuit in series with other components. Because the power switch is in parallel with the Zener diode and not in series, it can always be on. However, if the power switch is off, current can still flow through the Zener diode.
The circuit of
The secondary winding 616, 618 may be distributed anywhere, such as evenly between the first and second divided phase windings 604, 606, all on one pole, or unevenly between the first and second divided phase windings, such as a greater number of turns or coils on one secondary winding than another secondary winding.
In the example of
As shown in
As discussed below, the control circuit may include a diode rectifier bridge circuit whose output is connected to one or more power switches. As shown in
The control circuit 1114 controls switching for the power switch(es) circuit 1115 based on timing of the input frequency and rotor position. The control circuit 1114 controls the start-up and operation of the divided phase winding circuit. For example, the control circuit 1114 controls start-up, including where the motor is a synchronous motor. The control circuit 1114 determines the location of the rotor relative to the stator. The control circuit 1114 also determines and monitors the speed of the rotor, such as in revolutions per minute (RPMs), to determine operational parameters of the motor, such as when the motor has reached synchronous speed, and controls the motor based on the location of the rotor and/or speed of the motor. In one example, the control circuit 1114 has a Hall effect switch and/or other rotation determining device to determine the position of the rotor and/or rotation counting or speed determining device to determine the speed of the rotor.
In one example, the power switch(es) circuit 1115 includes a Zener diode 1116 or other voltage regulator and a power switch 1108 in parallel. Whereas, prior systems included the power switch in series with other components. Because the power switch 1108 is in parallel with the Zener diode 1116 and not in series, it can always be on. However, if the power switch is off, current can still flow through the Zener diode.
The circuit of
The secondary winding 1104, 1106 may be distributed anywhere, such as evenly between the first and second divided phase windings 1110, 1112, all on one pole, or unevenly between the first and second divided phase windings, such as a greater number of turns or coils on one secondary winding than another secondary winding.
The way that the coils are connected to the circuit via the diode bridge rectifier 1118 allow for current to flow through the coils in only one direction at any given time.
The improvements that have been made to this motor and controller greatly improve the DC logic power supply which enables a more reliable logic control circuit. Secondary coils 1104, 1106 are wound with the motor coils in a method that creates a transformer using the motor coils as the primary coils 1110, 1112. The example of
The power switch(es) circuit 1115 has a full wave bridge rectifier 1118 in addition to the MOSFET power switch 1108. The full wave bridge rectifier 1118 guarantees that no negative voltage will be supplied to the drain (top) of the power switch 1108. The full wave bridge rectifier 1118 also guarantees that no positive voltage will be supplied to the source (bottom) of the power switch 1108 so that current can only flow from the drain to the source of the power switch 1108 when biased by a positive voltage on the gate of the power switch 1108 via resistor R1. Simultaneously, as a positive rectified AC power supply is present at the drain of the power switch 1108, the power switch 1108 is biased by the same voltage signal via resistor R1. Diode 1116 protects the gate of the power switch 1108 by guaranteeing that any voltage on the gate of the power switch 1108 will be greater than −0.7 VDC, as anything less could damage or destroy the power switch 1108. Resistor R11 and capacitor C5 are used as a “snubber” to filter out transients or high frequency noise. R11 and C5 provide added protection for the MOSFET power switch 1108, especially in noisy environments.
In one embodiment, one purpose of the divided phase windings circuit 1202 is to allow a motor to run synchronously to the AC power supply line frequency (for example, for a 4 pole motor, 60 Hz=1800 rpm and 50 Hz=1500 rpm). Without any control circuitry, the power switch(es) circuit would allow current to flow as if coil pairs L1 and L2 were shorted together through the power switch(es) circuit. The control circuitry turns the power switch(es) circuit off until the rotor is in the proper position compared to the line voltage. For this reason, in one aspect, the power switch(es) circuit is rated for the AC power supply line voltage. The control circuitry components can all be at the logic level voltage (VCC).
Logic power is supplied by secondary coils 1104, 1106 that are wound on the same poles as the primary motor coils 1110, 1112. Secondary coils 1104, 1106 could be wound on any number of poles as long as the secondary power meets logic power requirements. In one example, the control circuit is only needed to start the motor and bring it to synchronous speed, and the logic control shut off circuit optionally is included to shut off the main control circuit. The logic control shut off circuit is optional. By shutting the control circuit off, the power switch(es) circuit will allow full line power to the motor minus any losses in the power switch(es) circuit. This will increase total efficiency and the life of components especially when the motor runs for long periods.
Power Switches Circuit
The power switch(es) circuit has a full wave bridge rectifier BR1 and a MOSFET power switch Q1. The full wave bridge rectifier BR1 guarantees that no negative voltage will be supplied to the drain (top) of the power switch Q1. The full wave bridge rectifier BR1 also guarantees that no positive voltage will be supplied to the source (bottom) of the power switch Q1 so that current can only flow from the drain to the source of the power switch Q1 when biased by a positive voltage on the gate of the power switch Q1 via resistor R1. A positive rectified AC power supply is present at the drain of the power switch Q1, the power switch Q1 is biased by the same voltage signal via resistor R1. Diode D5 protects the gate of the power switch Q1 by guaranteeing that any voltage on the gate of the power switch Q1 will be greater than −0.7 VDC, as anything less could damage or destroy the power switch Q1. Resistor R11 and capacitor C5 are used as a “snubber” to filter out transients or high frequency noise. R11 and C5 provide added protection for the MOSFET power switch Q1, especially in noisy environments.
DC Power Supply
As soon as power is applied to the motor and current is flowing through the motor phase windings (motor primary coils), there is power on the secondary windings (secondary coils) in the same manner as the operation of a transformer. The value of voltage on the secondary coils is directly proportional to the input voltage and the primary coils to secondary coils turn count ratio. Using the example in
Zener diodes Z1 and Z2 are connected in series with each other anode to anode, and each cathode is connected to the AC power supply inputs of the full wave bridge rectifier BR2. This method is used to protect the full wave bridge rectifier BR2 from AC power supply inputs that could exceed maximum ratings for the component. The negative output from the full wave bridge rectifier BR2 is connected to the circuit ground, which is also connected to the same ground as the power switch block. The positive output from the full wave bridge rectifier BR2 is connected to the low drop-out regulator LDO1 and capacitor C1. Capacitor C1 is provided to smooth the rectified AC power supply signal going to the input of the low drop-out regulator LDO1. A bypass capacitor C7 could be used on the output of the low drop-out regulator LDO1 to help reduce noise on the positive DC rail (VCC). Also, a larger capacitor C10 could be used on the output of the low drop-out regulator LDO1 to smooth the positive DC rail and ensure power during some low voltage situations. C7 and C10 are not required but are provided to add reliability and protection for low voltage DC components, especially in a noisy environment.
Logic Control Circuit/Motor Controller
The logic control circuit (motor controller) controls switching for the power switch(es) circuit based on timing of the AC supply line input frequency and rotor position. Timing of the AC supply line input frequency is sensed using an AC buffer that consists of bi-polar junction transistors (BJTs) Q2 and Q3 and diodes D6 and D7. Current to the AC buffer input is limited by a high value resistor R3. Diode D6 ensures that the AC buffer input is not greater than the positive DC supply voltage. Diode D7 ensures the AC buffer input is greater than −0.7 volts referenced to the DC supply ground.
When the input to the AC buffer is logic high, BJT Q2 is biased, and the output of the AC buffer is also logic high. When the input to the AC buffer is logic low, BJT Q3 is biased, and the output of the AC buffer is logic low. The output of the AC buffer is connected to a filter consisting of capacitor C6 and resistor R13. The filter is not required but provides protection and reliability in noisy environments.
Rotor magnet polarity is sensed using Hall-effect switch IC1. Though, another switch or sensing device may be used to sense rotor magnet polarity and/or rotor position and/or determine speed and/or determine rotor revolutions. The Hall-effect switch IC1 is an open-collector output and therefore requires a pull-up to the positive DC rail (VCC). Resistor R2 provides the pull-up required for the open-collector output.
The output of the Hall-effect switch IC1 and the output of the AC buffer are compared using a single circuit logic XOR IC2. The output of the XOR IC2 is the difference between the Hall-effect switch IC1 and the AC buffer, which will bias MOSFET power switch Q1 of the power switch(es) circuit. When the Hall-effect switch IC1 output is logic low, the power switch Q1 will only be biased when the AC supply input L1 to the motor is negative. When the output of the Hall-effect switch IC1 is logic high, the power switch Q1 will only be biased when the AC supply input L1 to the motor is positive. During motor start up, there can be multiple input AC cycles where either only the positive or only the negative inputs from AC supply input L1 will pass through the power switch Q1.
Using the power switch Q1, waveforms can be “chopped” or shut off at any time when the drain and gate voltage of the power switch Q1 is above biasing voltage. For example, see
When the frequency of the Hall-effect switch IC1 matches the frequency of the input AC supply, the motor is running synchronously. If the motor is running synchronously, the control circuit is not needed until either the motor falls out of sync or the motor is stopped and restarted. When the voltage regulator IC3 senses synchronous speed or greater from the Hall-effect switch IC1, the output of the XOR IC2 is held logic low via the open-collector output of the voltage regulator IC3. When the voltage regulator IC3 senses a speed that is less than that of the input AC supply, the open-collector output of the voltage regulator IC3 is off, which will leave the output of the XOR IC2 unaffected.
This method ensures that when the motor is running at a synchronous speed, the power switch Q1 is not shut off by the logic control. But, if the motor slows down below synchronous speeds, then the logic controller will control the motor timing as it does for start-up. Using this method improves overall motor efficiency and the expected lifetime of components in the circuit.
External components are used to set timing for the voltage regulator IC3. Resistors R4, R5, R6 and R7 may be 1% tolerance so that the voltage regulator IC3 operates within accurate parameters. Capacitor C1 operates in conjunction with the resistors R6 and R7 to set the frequency at which the open-collector output of the voltage regulator IC3 will turn on. Capacitor C3 is used for an internal charge pump in the voltage regulator IC3. Capacitor C4 is used to AC couple the input to the voltage regulator IC3 since the voltage regulator IC3 will only detect frequencies that have a zero-voltage crossing. Resistor R8 limits current to the AC couple capacitor C4 at the input of the voltage regulator IC3.
Diodes D1, D2, d1, and d2 perform the rectification of the AC power for the DC power supply for Hall switch/sensor IC1.
Zener diode ZD1 provides the voltage regulator for the Hall switch/sensor IC1's DC power supply.
RL provides current limiting for the DC power supply. In one example, it is set to approximately limit the current to 10 mA. The Hall switch/sensor IC1 uses 6 mA of DC current, including the base drive current for the internal open collector output transistor. Additional DC current will be used to turn on switch Q3 and is supplied through the pull up resistor R3. The collector to emitter current for switch Q3 and the base and collector to emitter current for switch Q4 is not supplied by the DC power supply but is supplied by the current through the motor phase windings. It is preferable to assure that transistors Q3 and Q4 turn completely ‘off’ at the proper times. In one embodiment that the switches turn fully ‘on’ or in saturation at the proper times for maximum operational efficiency.
The motor has a stator 2204 with 4 poles 2206-2212 and a rotor 2214 with 4 magnets N, S, N, S 2216-2222 facing the stator. The motor 2202 has a shaft (center circle) 2224 and rotor back iron (the area between the shaft and the magnets) 2226. The primary divided phase windings 2228, 2230 are connected to an AC power supply at L1 and L2, respectively. A secondary winding 2232, 2234 is connected to the DC power supply 2236.
The circuits of
Referring to the circuit of
The power electronics for the motor have two stages, with a first stage (stage 1) power switch(es) circuit/power electronics 2524 placed at a midpoint or center 2526, 2528 between two of the divided motor phase windings 2504-2506 and 2608-2610, respectively, on each half 2512-2514 of the motor phase windings (i.e. “quarter-point”). The stage 1 power switch(es) circuit activates the first (L1) and fourth (L4) coils 2504, 2510. The stage 1 power switch(es) circuit 2524 may be, for example, one or more switches, such as one or more MOSFETs or other switches, and is controlled by the stage 1 motor controller 2518.
A second stage (stage 2) power switch(es) circuit/power electronics 2530 is placed at a “mid-point” 2520 in the supply line voltage between the two halves 2512, 2514 of the divided motor phase windings 2504-2510. The stage 2 power switch(es) circuit 2530 activates the second (L2) and third (L3) coils 2506-2508. The stage 2 power switch(es) circuit 2530 may be, for example, one or more switches, such as one or more solid state relays (SSRs), quad solid state relays (QSSRs), or other switches, and is controlled by the stage 2 motor controller 2518. The direct current (DC) power supply 2532 (e.g. for the electronics used in the motor controller) is also located between the divided motor phase windings 2504-2510, between the two halves 2512-2514 of the divided motor phase windings and/or at a midpoint or center 2526-2528 between two of the divided motor phase windings 2504-2506 or 2508-2510 on each half 2512, 2514 of the motor phase windings.
The divided phase winding circuit 2502 includes one or more non-collapsing DC power supply components 2534, 2536 (components to prevent the DC voltage from the DC power supply from being reduced to or below the switch ‘on’ resistance times the current through the power switch(es), which is close to zero), including voltage drop components or direct DC power supply powering components to create a non-collapsing DC power supply. Examples of non-collapsing DC power supply components 2534, 2536 include a tap from one or more of the primary phase windings 2504-2510 electrically connected to the DC power supply 2532, a tap from the outer primary divided phase windings (coil L1 and coil L4) 2504 and 2510 electrically connected to the DC power supply 2532, a secondary phase coil winding connected to the DC power supply to power the power supply, a secondary phase coil electrically connected from the outer primary divided phase windings (coil L1 and coil L4) 2504 and 2510 to the DC power supply 2532, resistors between the divided phase windings and one or more of the power switch(es) circuits, one or more resistors between the first and second divided phase windings (coil L1 and coil L2) and one or more resisters between the third and fourth divided phase windings (coil L3 and coil L4) 2506 and 2508 where the DC power supply also is electrically connected one on side between the first and second divided phase windings (coil L1 and coil L2) and one the other side between the third and fourth divided phase windings (coil L3 and coil L4), one or more Zener diodes between the divided phase windings and one or more of the power switch(es) circuits, one or more Zener diodes between the first and second divided phase windings (coil L1 and coil L2) and one or more Zener diodes between the third and fourth divided phase windings (coil L3 and coil L4) where the DC power supply also is electrically connected one on side between the first and second divided phase windings (coil L1 and coil L2) and one the other side between the third and fourth divided phase windings (coil L3 and coil L4), a non-saturated semiconductor or other resistive component between the divided phase windings and one or more of the power switch(es) circuits (e.g. in place of the one or more resisters or diodes above) where the resistance is high enough to create a significant voltage drop and where this voltage drop causes the DC power supply when the switch is ‘on’, or other components to create a voltage drop between the primary divided phase windings and one or more of the power switch(es) circuits to prevent the DC power supply from collapsing when the power switch(es) in the power switch(es) circuit is/are on and conducting. The divided phase winding circuit 2502 therefore provides a constant flow of power regardless of whether the power switch(es) circuit is on and conducting or off and not conducting.
Referring to
The power electronics for the motor have two stages, with a first stage (stage 1) power switch(es) circuit/power electronics 2624 placed at a midpoint or center 2626, 2628 between two of the divided motor phase windings 2604-2606 and 2608-2610, respectively, on each half 2612-2614 of the motor phase windings (i.e. “quarter-point”). The stage 1 power switch(es) circuit 2618 activates the first (L1) and fourth (L4) coils 2604, 2610. The stage 1 power switch(es) circuit 2624 may be, for example, one or more switches, such as one or more MOSFETs or other switches, and is controlled by the stage 1 motor controller 2218. In one example, the stage 1 power switch(es) circuit 2618 includes one or more Zener diodes or other voltage regulator and a power switch in parallel. Whereas, prior systems included the power circuit in series with other components. Because the power switch is in parallel with the one or more Zener diodes and not in series, it can always be on. However, if the power switch is off, current can still flow through the Zener diode.
A second stage (stage 2) power switch(es) circuit/power electronics 2630 is placed at a “mid-point” 2620 in the supply line voltage between the two halves 2612, 2614 of the divided motor phase windings 2604-2610. The stage 2 power switch(es) circuit 2630 is electrically connected to the inner primary divided phase windings (second coil L2 and third coil L3) 2606 and 2608, and the stage 2 power switch(es) circuit activates the second (L2) and third (L3) coils. The stage 2 power switch(es) circuit 2630 may be, for example, one or more switches, such as one or more solid state relays (SSRs), quad solid state relays (QSSRs), or other switches, and is controlled by the stage 2 motor controller 2618.
In one example of
The direct current (DC) power supply 2632 (e.g. for the electronics used in the motor controller) is also located between the divided motor phase windings 2604-2610, between the two halves 2612-2614 of the divided motor phase windings and/or at a midpoint or center 2626-2628 between two of the divided motor phase windings 2604-2606 or 2608-2610 on each half 2612, 2614 of the motor phase windings. The primary divided phase winding 2604-2610 limits the current that can flow to the DC power supply 2632, thereby eliminating the need for current limiting components that waste power.
The divided phase winding circuit 2602 of
Referring still to
As shown in the example in
When the stage 1 power switch(es) circuit 2624 turns off and the stage 2 power switch(es) circuit 2630 turns on, the current path for all four phase windings 2604-2610 is completed. Since the stage 2 power switch(es) circuit 2630 has a slower switching speed than the stage 1 power switch(es) circuit 2624 at startup, a component such as a relay or a solid state relay can be used for the stage 2 power switch(es) circuit and require fewer parts than if a power switch like the MOSFET is used for the stage 2 power switch(es) circuit.
If low cost is a goal, it might be beneficial to build an equivalent circuit using cheaper discrete components. In one of the circuits described below, the use of discrete components performs well in voltage range, current range, voltage drop across, and switching speed. It can also be built for equal or less cost than a solid state relay that meets the same power requirements.
It also includes one or more secondary phase coil windings L1-1, L4-1 (
Stage 1 Power Switch(es) Circuit
The Power Switch block has a full wave bridge rectifier BR1 and a MOSFET Q1. The full wave bridge rectifier BR1 guarantees that no negative voltage will be supplied to the drain (top) of the MOSFET Q1 and guarantees that no positive voltage will be supplied to the source (bottom) of the MOSFET Q1 so that current can only flow from the drain to the source of the MOSFET Q1 when biased by a positive voltage on the gate of the MOSFET Q1 via a resistor R1 or a separate gate driver circuit. In the example of
Referring again to
The Zener diode Z1 will regulate higher voltages and should be a value within the MOSFET's range of normal operation. The Zener diode Z1 will regulate the amount of voltage equal to the voltage rating of the Zener diode; voltages higher than the rated Zener diode voltage are dropped across the Zener diode. The Zener diode Z1 can act as a voltage regulator. In this case, the voltage is regulated to be within the operating voltage of the MOSFET Q1.
In a configuration like the example of
Stage 2 Power Switch(es) Circuit
The purpose of the stage 2 power switch(es) circuit is to run the motor in the most efficient way possible. Since stage 2 is rarely required to switch off and on or on and off within 1 input cycle, it can be designed to operate very simply. The only input needed from the stage 1 control logic/motor controller is a synchronous shut down input, SYNC SD. The SYNC SD input is used to shut down the stage 1 MOSFET Q1 by pulling its gate to its source. The SYNC SD input also is used to turn the stage 2 power switch(es) circuit on for as long as the motor speed is running synchronous to the input frequency. In the example circuit in
In other embodiments, alternating current (AC) driven synchronous motors and associated control circuits and power switch(es) circuits for the AC synchronous motors achieve very high efficiency at multiple fixed speeds, including fully synchronous speed and fractions of that synchronous speed. The fully synchronous speed is determined by the frequency of the alternating current power source and the number of rotor poles and stator poles of the motor. The motor stator includes at least one phase winding. However, the motor stator may have multiple phase windings, such as in the above-embodiments. One or more additional phase windings, and additional control circuitry for the control circuit, may be added to optimize performance at one or more selected fractional speeds or other fractional speeds.
The stator winding Wa is connected (at point A 3508) on one side of the winding between two power switches Q1 and Q2 on one side of the multispeed AC machine circuit 3502 and (at point B 3510) on the other side of the winding between the other two power switches Q3 and Q4 on the other side of the multispeed AC machine circuit. Point A 3508 is the start side of the winding Wa, and point B 3510 is the end side of the winding.
In the example of
In the example of
The control circuit 3506 controls operation of the multispeed AC machine circuit 3502. The control circuit 3506 determines which one or more of the power switches Q1, Q2, Q3, and/or Q4 to close to obtain the proper direction of current flow through one or more windings in the multispeed AC machine circuit 3502. In one example, the control circuit 3506 opens power switches Q1 and Q4 and closes power switches Q2 and Q3 to cause current to flow from L1 to L2. In another example, the control circuit 3506 opens power switches Q2 and Q3 and close power switches Q1 and Q4 to cause current to flow from L2 to L1.
In one example, the control circuit 3506 includes a hardware processor with software executing one or more instructions stored on a non-transitory computer readable storage medium. In another example, the control circuit 3506 includes a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array signal (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or combinations thereof designed to perform the functions described herein.
The DC power supply 3602 converts the incoming AC power to a DC voltage configured to power the DC powered components in the control circuit 3506A, such as the Hall effect device 3606 and the motor controller 3608. The DC power supply 3602 then supplies power to the DC powered components in the control circuit 3506A, such as the Hall effect device 3606 and the motor controller 3608. In one example, the DC power supply 3602 includes an IC Offline Converter in a buck topology to convert power from the incoming AC power to low voltage DC power. This low voltage DC power is used to power, and supplied to, one or more DC powered devices in the control circuit 3506A, such as the Hall effect device 3606 and the motor controller 3608.
The AC polarity detector 3604 detects whether the voltage is higher at L1 or L2 and outputs a polarity signal indicating which of L1 or L2 has the higher voltage, such as indicating whether the voltage at L1 is higher or lower than the voltage at L2. In one example, if the AC polarity detector 3604 detects the voltage at L1 is higher than the voltage at L2, the AC polarity detector outputs a polarity signal that is high, meaning voltage on L1 is higher than L2. If the AC polarity detector 3604 detects the voltage at L1 is lower than the voltage at L2, the AC polarity detector outputs a polarity signal that is low, meaning voltage on L1 is less than the voltage on L2.
In one example, as shown in
The Hall effect device 3606 senses the position of the rotor relative to stator and outputs one or more Hall Effect signals indicating the position of the rotor relative to the stator. In one example, the Hall effect device 3606 senses a polarity of a magnet of the rotor relative to a stator tooth. In this example, the Hall effect device 3606 outputs a high Hall Effect signal or a low Hall Effect signal that is determined by the polarity of the magnetic pole it is sensing. In this example, the Hall effect device 3606 outputs (1) a high Hall Effect signal indicating a north magnetic pole is facing the stator or (2) a low Hall Effect signal indicating a south magnetic pole is facing the stator.
In one example, the location of the Hall effect device 3606 relative to the stator provides a high output when the back electromotive force (BEMF) of the motor is high. The Hall effect device 3606 is then shifted 36 electrical degrees advanced on the BEMF. The BEMF is generated by the combination of the rotor magnets on the spinning rotor passing by the stator teeth with the windings. The BEMF is determined, in one example, by the speed of the rotor and the number of turns on each pole.
The motor controller 3608 determines which one or more of the power switches Q1, Q2, Q3, and/or Q4 to close to obtain the proper direction of current flow through one or more windings in the multispeed AC machine circuit 3502. In one example, the motor controller 3608 opens power switches Q1 and Q4 and closes power switches Q2 and Q3 to cause current to flow from L1 to L2. In another example, the motor controller 3608 opens power switches Q2 and Q3 and close power switches Q1 and Q4 to cause current to flow from L2 to L1.
In one example, the motor controller 3608 receives signals from the AC polarity detector 3604 and the Hall effect device 3606 to determine which one or more of the power switches Q1, Q2, Q3, and/or Q4 to close to obtain the proper direction of current flow through one or more windings in the multispeed AC machine circuit 3502. In this example, when the Hall Effect signal is high, current should be flowing through the winding Wa from point A 3508 to point B 3510.
If the Hall Effect signal is high and the AC polarity detection signal is high, meaning the voltage on L1 is higher than the voltage on L2, the motor controller 3608 will transmit signals to power switch pair Q2/Q3 to open power switch pair Q2/Q3 and transmit signals to power switch pair Q1/Q4 to close power switch pair Q1/Q4. In this instance, the higher voltage is applied to point A 3508 of the winding Wa, and the lower voltage is applied to point B 3510 of the winding Wa to create current flow from point A 3508 to point B 3510 through the winding Wa.
If the Hall Effect signal is high and the AC polarity detection signal is low, meaning the voltage on L1 is less than the voltage on L2, the motor controller 3608 will transmit signals to power switch pair Q1/Q4 to open power switch pair Q1/Q4 and transmit signals to power switch pair Q2/Q3 to close power switch pair Q2/Q3. This still applies the higher voltage to point A 3508 of the winding Wa and the lower voltage to point B 3510 of the winding Wa to create current flow from left to right through the winding, which is the correct direction of flow when the Hall effect signal is high.
If the Hall Effect signal is low and the AC polarity detection signal is high, meaning the voltage on L1 is higher than the voltage on L2, the motor controller 3608 will transmit signals to power switch pair Q1/Q4 to open power switch pair Q1/Q4 and transmit signals to power switch pair Q2/Q3 to close power switch pair Q2/Q3. In this instance, the higher voltage is applied to point B 3510 of the winding Wa, and lower voltage is applied to point A 3508 of the winding Wa to create current flow from point B 3510 to point A 3508 through the winding Wa, which is the correct direction of flow when the Hall effect signal is low.
If the Hall Effect signal is low and the AC polarity detection signal is low, meaning the voltage on L1 is less than the voltage on L2, the motor controller 3608 will transmit signals to power switch pair Q2/Q3 to open power switch pair Q2/Q3 and transmit signals to power switch pair Q1/Q4 to close power switch pair Q1/Q4. This still applies the higher voltage to point B 3510 of the winding Wa and the lower voltage to point A 3508 of the winding Wa to create current flow from point B 3510 to point A 3508 through the winding Wa, which is the correct direction of flow when the Hall effect signal is low.
In one example, the motor controller 3608 includes a hardware processor with software executing one or more instructions stored on a non-transitory computer readable storage medium. In this example, the processor processes Hall effect signal and the AC polarity signal and creates one or more driving logic signals based on whether each of the Hall effect signal and the AC polarity signal is high or low, and the motor controller transmits the one or more driving logic signals to the power switches (as described above) to open and close the power switches. In one example, the motor controller 3608 includes logic in which the Hall effect signal and the AC polarity signal are XOR'd together to create one or more driving logic signals based on whether each of the Hall effect signal and the AC polarity signal is high or low, and the motor controller transmits the one or more driving logic signals to the power switches (as described above) to open and close the power switches.
In another example, the motor controller 3608 includes a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array signal (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or combinations thereof designed to perform the functions described herein. A hardware processor may be a microprocessor, commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of two computing components, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The rotor magnets 3714-3724 are magnetized radially through the center of the magnet. The rotor magnets 3714, 3718, and 3722 with the mark on top have a north pole on the outside diameter (OD) and a south pole on the inside diameter (ID). The rotor magnets 3716, 3720, and 3724 with no marking have a south pole on the outside diameter (OD) and a north pole on the inside diameter (ID).
In the example of
Referring to
Starting mode is used for start-up of the motor in which the multispeed AC machine circuit 3502 is used. Starting mode can be operated in multiple different ways, including pulse-width modulation, delayed firing angle with zero current shutoff, or using a second winding. The different starting modes are used to limit starting current and torque to provide smooth stable operation.
Pulse-width modulation (PWM) mode may be used, for example, in a multispeed AC machine circuit 3502 with one winding Wa, as seen in
The control circuit 3506 has a microcontroller that generates one or more PWM signals to one or more of the power switches Q1, Q2, Q3, and/or Q4. The PWM signals open or close the one or more of the power switches Q1, Q2, Q3, and/or Q4. For example, the control circuit 3506 transmits the PWM signals to the power switch pairs Q1/Q4 or Q2/Q3 as described herein to open or close the power switch pairs Q1/Q4 or Q2/Q3.
The PWM signal has a duty cycle, which for example can be based on the amount of starting torque/current that is required to start the motor. For example, a compressor motor would require a higher duty cycle/starting torque than a fan motor to start. The control circuit 3506 continuously determines the actual duty cycle value and compares the actual duty cycle value to a desired duty cycle value. In this example, when the desired duty cycle is reached, if the power switch pair Q1/Q4 is closed and the AC polarity detection signal is high, indicating that current is flowing from L1 through the winding Wa from point A 3508 to point B 3510 out to L2, the control circuit 3506 opens power switch Q4 and closes power switch Q2. This connects both point A 3508 and point B 3510 of winding Wa to L1. Since both sides of the winding Wa are connected to the same voltage source, there is no differential voltage applied to the winding. This allows current to continue to flow through the winding in the same direction Wa, while no voltage is applied to the winding Wa until the next PWM cycle is reached. Then, the control circuit 3506 opens power switch Q2 and closes power switch Q4, thereby applying voltage to the windings again. Alternatively, if power switch pair Q1/Q4 were closed when the AC polarity detection signal 3604 is low, indicating that current was flowing from L2 through winding Wa from point B 3510 to point A 3508 and out to L1, and the desired duty cycle is reached, the control circuit 3506 would open power switch Q1 and close power switch Q3. This allows current to continue to flow through the winding Wa in the same direction without voltage applied to the winding Wa. The current must always have a path to flow to operate the PWM without shut-off spikes. PWM may also be used in the other operating modes to limit peak currents.
In synchronous speed mode, the motor is operating at synchronous speed. Synchronous speed rotations per minute (RPM) can be determined by taking the line frequency in Hertz divided by the number of rotor pole pairs (1 north pole and 1 south pole is equal to 1 pole pair) and multiplied by 60, the number of seconds in a minute. For example a six pole motor (3 north poles and 3 south poles) running on a 60 Hz supply would have a synchronous speed of 1200 RPM because 60 Hz/3 pole pairs*60 sec=1200 RPM. In full synchronous speed mode, one pair of power switches Q1/Q4 or Q2/Q3 is left always closed and the other pair Q2/Q3 or Q1/Q4 is left always open allowing continuous alternating current flow through the winding Wa.
Delayed firing angle with zero current shutoff mode may be used in starting mode to limit starting current/torque and also in fractional speed mode, as shown in
Fractional speed mode is used when the motor is operating at less than full synchronous speed. Fractional speed mode may be operated multiple ways by the motor controller 3608, including using the delayed firing angle with zero current shutoff to adjust the power applied to the winding Wa or adding additional windings and using a simplified circuit, as seen in
The example of
In the example of
In one example of operation, as shown in
In another example of operation, as shown in
In one example of operation of a full speed setting and operation by the multispeed AC machine circuit 3502, the startup mode is only used at speeds lower than 400 RPM and both windings Wa and Wb are used. Once the motor is moving faster than 400 RPMs, the winding Wb is no longer used. Pulse-width modulation is used, as described above, to limit current after that point. The Hall effect signal and the AC polarity signal are XOR'd together by the control circuit 3506B to create a driving logic signal. Once the motor reaches full speed, the Hall effect signal is shifted as described above. The Hall effect signal is retarded for an over-rev condition and advanced for under-rev condition. The Hall effect signal is shifted for every sensor period that is outside of a 100 micro second window. The Hall effect signal shifts different amounts based on how far outside of the window it is.
In this example, for full speed synchronous mode, there is a 1 micro second window that the sensor time period has to be in for 5 seconds before the circuit will try to become synchronous. Once the motor has been stable inside this window for 5 seconds the software determines which 2 power switches have been on the most and it leaves them on. No more switching occurs unless an over current situation is detected or a change in speed is detected.
In this example, for half speed, once 600 rpm is achieved, the circuit will continue to switch with the hall but only when the AC detection signal is high. The sensor is then shifted in the software to get the motor to stabilize at 600 rpm. It is retarded for an over-rev condition and advanced if more power is needed. The sensor never advances past its actual location.
In other embodiments, the disclosure herein includes methods for providing the components described herein for a machine, including for a motor or a generator.
In one aspect, a multispeed alternating current (AC) machine circuit is for an AC power source having a first side and a second side. The AC machine circuit includes two or more pairs of power switches, one or more windings, and a control circuit to close one pair of power switches to cause current to flow from a first side of the AC power source, through the one or more windings, to the second side of the AC power source and to close the other pair of power switches to cause current to flow from the second side of the AC power source, through the one or more windings, to the first side of the AC power source.
In another aspect, a circuit is for a machine having alternating current (AC) power source having a first side (L1) and a second side (L2). The circuit comprises a winding with a start side and an end side, a first power switch connected between the first side and the winding start side, a second power switch connected between the second side and the winding start side, a third power switch connected between the first side and the winding end side, a fourth power switch connected between the second side and the winding end side, and a control circuit. The control circuit closes the first power switch and the fourth power switch and open the second power switch and the third power switch to cause current to flow from the first side to the second side or closes the second power switch and the third power switch and open the first power switch and the fourth power switch to cause current to flow from the second side to the first side.
In another aspect, a circuit is for a machine having alternating current (AC) power source having a first side (L1) and a second side (L2). The circuit comprises a first winding with a first start side and a first end side, a second winding with a second start side and a second end side, a first power switch connected between the AC power source first side and the first winding start side, a second power switch connected between the AC power source second side and the first winding start side, a third power switch connected between the AC power source first side and the first winding end side, a fourth power switch connected between the AC power source second side and the first winding end side, a fifth power switch connected between the AC power source first side and the second winding end side, a sixth power switch connected between the AC power source second side and the second winding end side, and a control circuit. The control circuit closes the first power switch and the sixth power switch and open the second power switch, the third power switch, the fourth power switch, and the fifth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the third power switch and the fourth power switch and open the first power switch, the second power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the first power switch and the fifth power switch and open the second power switch, the third power switch, the fourth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation or closes the second power switch and the fourth power switch and open the first power switch, the third power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation.
In another aspect, a method is for a multispeed alternating current (AC) machine circuit for an AC power source having a first side and a second side. The method includes providing two or more pairs of power switches, providing one or more windings, and providing a control circuit to close one pair of power switches to cause current to flow from a first side of the AC power source, through the one or more windings, to the second side of the AC power source and to close the other pair of power switches to cause current to flow from the second side of the AC power source, through the one or more windings, to the first side of the AC power source. The method further includes providing components for the control circuit described herein and operating the circuit as described herein.
In another aspect, a method is for a circuit for a machine having alternating current (AC) power source having a first side (L1) and a second side (L2). The method comprises providing a winding with a start side and an end side, providing a first power switch connected between the first side and the winding start side, providing a second power switch connected between the second side and the winding start side, providing a third power switch connected between the first side and the winding end side, providing a fourth power switch connected between the second side and the winding end side, and providing a control circuit. The control circuit closes the first power switch and the fourth power switch and open the second power switch and the third power switch to cause current to flow from the first side to the second side or closes the second power switch and the third power switch and open the first power switch and the fourth power switch to cause current to flow from the second side to the first side. The method further includes providing components for the control circuit described herein and operating the circuit as described herein.
In another aspect, a method is for a circuit for a machine having alternating current (AC) power source having a first side (L1) and a second side (L2). The method comprises providing a first winding with a first start side and a first end side, providing a second winding with a second start side and a second end side, providing a first power switch connected between the AC power source first side and the first winding start side, providing a second power switch connected between the AC power source second side and the first winding start side, providing a third power switch connected between the AC power source first side and the first winding end side, providing a fourth power switch connected between the AC power source second side and the first winding end side, providing a fifth power switch connected between the AC power source first side and the second winding end side, providing a sixth power switch connected between the AC power source second side and the second winding end side, and providing a control circuit. The control circuit closes the first power switch and the sixth power switch and open the second power switch, the third power switch, the fourth power switch, and the fifth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the third power switch and the fourth power switch and open the first power switch, the second power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the first power switch and the fifth power switch and open the second power switch, the third power switch, the fourth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation or closes the second power switch and the fourth power switch and open the first power switch, the third power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation. The method further includes providing components for the control circuit described herein and operating the circuit as described herein.
Those skilled in the art will appreciate that variations from the specific embodiments disclosed above are contemplated by the invention. The invention should not be restricted to the above embodiments, but should be measured by the following claims.
Claims
1-32. (canceled)
33. A circuit for a machine having alternating current (AC) power source having a first side (L1) and second side (L2), the circuit comprising:
- a winding with a start side and an end side;
- a first power switch connected between the first side and the winding start side;
- a second power switch connected between the second side and the winding start side;
- a third power switch connected between the first side and the winding end side;
- a fourth power switch connected between the second side and the winding end side; and
- a motor controller configured to: receive a signal from an AC polarity detector and another signal from a Hall effect device and determine which of the power switches to open or close to obtain a proper direction of current flow through the winding based on the signal and the other signal.
34. The circuit of claim 33 wherein:
- the AC polarity detector outputs a polarity signal as the signal;
- the Hall effect device outputs a Hall effect signal as the other signal;
- the signals received by the motor controller from the AC polarity detector and the Hall effect device include the polarity signal and the Hall effect signal; and
- based on a value of the polarity signal and a value of Hall effect signal received by the motor controller, the motor controller is configured to: close the first power switch and the fourth power switch and open the second power switch and the third power switch; or close the second power switch and the third power switch and open the first power switch and the fourth power switch.
35. The circuit of claim 33 wherein:
- the AC polarity detector outputs a polarity signal, the polarity signal having a high value or a low value;
- the Hall effect device outputs a Hall effect signal, the Hall effect signal having a high value or a low value; and
- the motor controller is configured to: receive the polarity signal and the Hall effect signal; when the Hall effect signal is high and the AC polarity detection signal is high, open the second power switch and the third power switch and close the first power switch and the fourth power switch; when the Hall effect signal is high and the AC polarity detection signal is low, open the first power switch and the fourth power switch and close the second power switch and the third power switch; when the Hall effect signal is low and the AC polarity detection signal is high, open the first power switch and the fourth power switch and close the second power switch and the third power switch; and when the Hall effect signal is low and the AC polarity detection signal is low, open the second power switch and the third power switch and close the first power switch and the fourth power switch.
36. The circuit of claim 33 further comprising a direct current (DC) power supply to receive alternating current (AC) power transferred from the AC power source, convert the AC power to DC power, and transfer the DC power to one or more components of the circuit.
37. The circuit of claim 33 wherein each power switch includes four diodes configured as a full wave bridge rectifier.
38. The circuit of claim 33 wherein the motor controller includes at least one of a processor, an application specific integrated circuit (ASIC), a field programmable gate array signal (FPGA), a programmable logic device (PLD), gate logic, and transistor logic.
39. The circuit of claim 33 wherein each power switch includes a MOSFET.
40. The circuit of claim 33 wherein each power switch includes a high speed SSR and a plurality of diodes configured as a full wave bridge rectifier.
41. The circuit of claim 33 wherein the machine includes a motor.
Type: Application
Filed: Apr 19, 2023
Publication Date: Sep 14, 2023
Applicant: QM Power, Inc. (Charlotte, NC)
Inventors: Charles J. FLYNN (Greenwood, MO), Cooper N. Tracy (Belton, MO), W. Scott Hunter (Kansas City, MO), Stephen B. Nichols (Somerville, MA)
Application Number: 18/303,461
