Abstract: A motor control system for use in heating, ventilation, and air conditioning applications includes a blower, a motor coupled to drive the blower, an inverter coupled to provide energization to the motor, and a controller coupled to the inverter. The controller provides signals to control the output of the inverter in response to received input control signals. Input control signals received by the controller can define first and second operating states. In response to the input control signals defining the first operating state, the controller controls the output of the inverter in accordance with a first volts vs. hertz relationship. In response to the input control signals defining the second operating state, the controller controls the output of the inverter in accordance with a second volts vs. hertz relationship, where the first volts vs. hertz relationship is different than the second volts vs. hertz relationship.

Abstract: A method for measuring the current in each phase of a three-phase motor (26) by the sensor (32), the motor (26) being controlled by a plurality of switching devices (S1-S6) that receive pulse width modulation signals from a controller (34). In one embodiment, a first and second sampling window (t1 and t2) are monitored. When both the first and second sampling windows (t1 and t2) are less than a minimum sampling window (mw), the voltage pulse trains associated with the highest output (V_h) and the lowest output (V_l) are shifted to form a first modified sampling window (t1′) and a modified second sampling window (t2′). When the first sampling window (t1) is less than the minimum sampling window and the second sampling window (t2) is greater than the minimum sampling window (mw), then the voltage pulse train associated with the highest output (V_h) and/or the middle output (V_m) may be shifted to form the first and second modified sampling windows (t1′ and t2′).

Abstract: A controller for a multiplex winding motor. When a multiplex winding motor is driven and controlled by inverters and each winding includes a current control system, the controller compensates interference between the current control systems of windings. Voltage non-interacting arithmetic sections compute a voltage command value supplied to voltage applying sections, which are connected to a set of windings, not only by using an output value of a current control section for controlling current in one winding but also using an output value of a current control section for controlling current in another winding, so that voltage interference between the current control sections is compensated.

Abstract: A motor drive device of the invention has means for producing a pulse signal having a fixed amplitude by comparing a drive signal that is a sinusoidal signal synchronous with the rotation of a motor with a predetermined high-frequency signal, and the switching of a switching device connected between a power source and the motor is controlled by the pulse signal. This prevents the lowering of the switching speed of the switching device connected between the power source and the motor near the zero-cross points of the sinusoidal drive signal. This helps minimize switching loss and enhance power efficiency. Moreover, the phase current that flows through the motor comes to have a sinusoidal waveform. This helps enhance rotation characteristics.

Abstract: The present invention relates to a method and an apparatus for controlling an electric motor by regulating at least the current Iout, the voltage Uout and the frequency fout to an input of said motor, where the number of revolutions of said electric motor is proportional to said frequency fout. If an available power Pin from an energy source is greater than or equal to the nominal requested power Pnom of said electric motor, the current Iout, voltage Uout and frequency fout are set to there corresponding nominal values Inom, Unom and fnom, respectively, to achieve said requested power Pnom and frequency fnom. If said available power Pin is less than the requester power Pnom, the voltage Uout and the frequency fout are reduced such that the relation between the voltage Uout and the frequency fout is essentially constant while said current Iout is kept at its nominal value Inom.

Abstract: This invention relates to a system for limitation of the output current from a speed controller for three-phase asynchronous electric motors, comprising a PWM type converter in which the electronic switches are controlled by a microcontroller circuit (Mc), characterized by the fact that the microcontroller circuit comprises means (LIC) of calculating the modulus of the current vector using motor phase current measurements, and comparing it with a limitation set value in order to obtain a limitation error (y) and to calculate a correction voltage (&Dgr;V) that is added to the control voltage (V) applied to the motor.

Abstract: A power semiconductor module that automatically sets an optimum dead time without being affected by the switching characteristics or driving mode of individual power semiconductor devices. The power semiconductor module includes a pair of IGBTs disposed in an upper and lower arm, respectively, and driving circuits for driving IGBTs. The power semiconductor module includes current detecting circuits and zero current detecting circuits for detecting that the output current of each of the IGBTs has become nearly zero, an inverting circuit, upper arm driving circuit and lower arm driving circuit for generating actual driving signals for each IGBT, using the output signals of the zero current detecting unit and ON commands for the IGBTs of the other arms.

Abstract: A motor driver having output circuits each including upper and lower side switching elements connected in series. The motor driver includes: a current detection resistance connected in series with the output circuits in common; a phase switch circuit for turning ON a switching element on one side of one of the output circuits for a time period corresponding to a predetermined electrical angle and switching switching elements on the other side of a plurality of output circuits among the remaining ones of the output circuits; and an ON-period control section for generating a signal for controlling the switching operation so that each of periods obtained by dividing the time period includes a first period in which a plurality of switching elements are turned ON and a second period in which one of the switching elements turned ON in the first period is kept ON.

Abstract: A method and apparatus for generating stator and rotor resistance estimate, the method including the steps of providing high frequency injection voltage signals to a three phase motor, rotating three phase feedback current therefrom, converting the feedback currents to two phase currents that represent the high frequency component of the current vector wherein the d and q axis components are within a two phase voltage coordinate system and driving a regulator via one of the current components to generate a lag angle estimate, the lag angle estimate used to solve any of several different equations to calculate the stator and rotor resistance estimates.

Abstract: A motor drive 50 of an induction motor IM includes an inverter section 20, a charger 60, a charging and discharging circuit 70 and a control section 80. The charger 60 is for storing regenerated electric power of the induction motor via the inverter section. The charging and discharging circuit 70 is for making the charger charge electric power and making the charger discharge the electric power. The control section carries out control of the charging and discharging circuit for making the charger charge the electric power when the induction motor generates regenerated electric power and making the charger supply the electric power to the induction motor in accelerating the induction motor or in electricity interruption.

Abstract: A motor controller for a motor operated by an AC line voltage includes solid-state switches connectable between an AC line and a motor terminal for controlling application of AC line voltage to the motor. A current sensor senses motor current. A control circuit is connected to the switches and the current sensor for varying relative duration of on time and off time during each cycle of line voltage to control motor voltage. The control circuit determines on time during each cycle of line voltage and compensates sensed motor current responsive to the sensed on time.

Abstract: A method and apparatus for monitoring voltage input to an appliance, such as a dryer, sensing when power input to the appliance is lost. In addition, a controller in the appliance pulses relay coils controlling motors and/or heating devices within the appliance to conserve energy on a backup capacitor that supplies the control circuit of the appliance in the event of power loss. Further, a voltage sense circuit outputting a square wave effects monitoring of the input voltage to the appliance by outputting the square wave signal whose cycle period is monitored to determine power outage. The controller stores current operation settings at the time of power outage in a memory device and ensures proper storage through the extra energy conserved from the capacitor by the pulsing of the relay coils.

Abstract: Method and system for controlling an induction machine are provided. The method allows to sense rotor position of the induction machine using a relatively low-resolution rotor position sensor configured to supply a stream of pulses indicative of angular increments as the rotor position changes. A memory device is used for storing a synchronous angle boost function. The method further allows to retrieve from the memory device at least one function parameter for providing a synchronous angle boost during a start up mode of operation of the induction machine. Upon sensing a predetermined number of pulses from the rotor position sensor, the method allows to switch from the start up mode of operation to a normal mode of operation, wherein the boost provided to the synchronous angle is discontinued upon switching to the normal mode of operation.

Abstract: An electrical rotating apparatus comprises an inverter system that outputs more than three phases. The apparatus further includes a stator comprising a plurality of slots and full span concentrated windings, with the windings being electrically coupled to the inverter system, and a rotor electromagnetically coupled to a magnetic field generated by the stator. A signal generator generates a drive waveform signal, that has a fundamental frequency, and the drive waveform signal drives the inverter system. The drive waveform signal has a pulsing frequency and is in fixed phase relation to the fundamental frequency. Additionally, the inverter system may be fed by a drive waveform signal that is fed through at least one signal delay device.

Abstract: A method and apparatus for controlling flux in an induction motor. During initial start of an induction motor drive the motor flux has to be charged up. The method provides time optimal flux forcing under limited inverter ampere capability. Command stator flux and current are generated and coordinated through a motor flux model. Charging of the motor flux and flux current are accelerated up to nominal operating values in coordinated manner.

Abstract: An apparatus and method for controlling a motor/blower system to provide a constant fluid flow by iteratively loading revised stator frequency values and stator voltage values to a variable frequency drive. Target DC bus current values corresponding to constant fluid flow rates are predetermined and stored as a function of the desired fluid flow rate, the operating frequency, and system specific constants or calculated by the controller as a function thereof during system operation. Actual DC bus current is measured with a current sensor and compared with the target DC bus current. Operating frequency is estimated using a PI controller based on the difference between measured and target DC bus current values. Operating voltage values corresponding to operating frequencies and system specific constants are predetermined and stored in memory or calculated by the controller during system operation. An updated target DC bus current, operating frequency and operating voltage are determined upon each iteration.

Abstract: A variable output induction motor drive system for use with a polyphase variable output alternating current motor including a rotor and stator to drive an operating load such as an automotive vehicle, the variable output induction motor drive system comprises a sine wave current generator operatively coupled to a direct current power source to receive direct current therefrom and to generate a variable sine wave current and operatively coupled to the polyphase variable output alternating current motor to selectively feed the variable sine wave current thereto and a sine wave current control coupled between the sine wave power current generator and the polyphase variable output alternating current motor to monitor the operating parameters of the polyphase variable output alternating current motor and to control the amplitude and frequency of the variable sine wave current fed from the sine wave current generator to the polyphase variable output alternating current motor to control the output torque and speed t

Abstract: A method of reconnecting a motor to a motor drive comprises controlling a current which flows through the motor using a current regulator. The current regulator produces a voltage command output based on a current command input. A current is commanded at the current command input of the current regulator. Back EMF measurements are acquired at different instants in time by monitoring the voltage command output of the current regulator. Back EMF phase angles are determined for a plurality of the instants in time based on a respective plurality of the back EMF measurements. A frequency of the back EMF is determined based on the back EMF angles determined for the plurality of instants in time. The motor drive is reconnected to the motor based on the frequency of the back EMF.

Abstract: A power electrical system is disclosed for a microturbine power generator. The invention permits the microturbine to be started using an external DC power source. The DC voltage is converted to a variable DC voltage by means of a bi-directional buck-boost circuit, DC bus and a DC-to-AC converter. The DC-to-AC converter produces at its output a fixed voltage pattern whose frequency is gradually increased in concert with the DC voltage, to accelerate the microturbine from standstill to startup speed. Once the microturbine is started, the excitation is discontinued, and the DC bus and DC-to-AC are used to produce output AC power at a voltage level and frequency to match an electrical load.

Abstract: In order to measure the rotation speed of an induction machine whose stator is connected via a controllable AC controller to a single-phase or polyphase AC power supply system, the stator is disconnected from the AC power supply system for at least a predetermined time period (&Dgr;t). This is preferably achieved by opening active devices in the AC controller, with at least one stator voltage, which is induced in the stator by the rotary movement of the rotor, being measured in this time period (&Dgr;t). The measured values are used to determine the frequency of the stator voltage and to derive the rotation speed of the induction machine.

Abstract: A method and apparatus for deriving characteristics of a utility signal for synchronizing the output of a motor drive with the utility for a transfer or capture operation. With the drive in idle, the voltage and phase angle of an input to the drive are detected by instrumentation of the drive. The voltage and phase angle of a signal from a utility are detected by instrumentation of the drive at the output of the drive. A phase angle difference and scaling factor are determined to correlate the input signal to the motor drive with the signal at the output of the motor drive. The phase angle difference and scaling factor are stored and subsequently used to derive the signal at the motor due to the utility at the time of the transfer or capture procedure.

Abstract: A polyphase induction motor is operated by an inverter drive system comprising a logic level controller. A number, preferably twelve or more, of independently driven phases causes harmonic fields, up to a number equal to the number of phases, to oscillate in synchrony with the fundamental oscillating field. A pulse-width modulation (“PWM”) carrier is used by the logic level controller to synthesize a desired drive alternating current, in which the pulsing distortion produced by the pulse width modulation produces a synchronous oscillating field in the driven polyphase induction motor.

Abstract: A method and an apparatus for controlling an induction motor which allow torque generated by an induction motor upon starting operation to be increased without need for employment of expensive switching elements of large current capacity.

Abstract: The invention concerns a method for varying and regulating the speed of a motor powered from a voltage source via a triac, comprising, at least once every alternating voltage interval, the following steps: computing a surface value (SI) corresponding to the current absorbed (I(M)) in a time window (FT) defined between a current switching-on time (ti) and a following current switching-off time (tf); computing an interval of the next triac-blocking time (t′); and controlling the starting of the triac when the blocking time (t′) has elapsed. The invention is useful in particular for household electric and house automation appliances operating at variable speed.

Abstract: A method and apparatus for correcting DC offset in a frequency to voltage converter. An analog frequency to voltage converter receives a frequency signal and outputs a voltage signal having a level that is indicative of the frequency of the frequency signal. The frequency signal is also input into a digital processor which converts the frequency signal into a reference signal that is fed back and summed with the voltage signal. The processor integrates the difference between the reference signal and the output signal to drive the output signal to be equal to the reference signal thereby nullifying DC offset in the output signal. The invention can be applied to controlling the DC bus voltage in a variable frequency AC drive.

Abstract: In a control apparatus of an induction motor including an inverter for converting a direct current to an alternating current having a variable voltage and variable frequency in accordance with a pulse width modulation control, and a controller for controlling an output voltage of said inverter through a modulation rate which is requested in accordance with an exciting magnetic current component command in a primary current of the induction motor driven by said inverter and a voltage component command corresponding to said respective components which are executed in accordance with a torque current component command, the control apparatus of the induction motor operates to detect a torque current component in accordance with said primary current of the induction motor, to correct said torque current component from a deviation between said detected torque current component value and said command value, to correct an output frequency of said inverter in accordance with said corrected torque current component com

Abstract: A method for detecting a change in motor load and/or motor speed is provided. The method includes the step of measuring the number of transitions (i.e., state changes) of a phase control signal in a motor phase of the motor. The method also includes the step of comparing the number of transitions to a predetermined number that is indicative of a predetermined motor load and/or motor speed. The predetermined number may comprise the number of transitions in a prior phase control signal of the motor. A method for controlling a motor responsive to a change in motor load and/or motor speed is also provided. The method includes the above-described steps for detecting a change in motor load and/or motor speed and further includes the step of selecting one of a plurality of operating modes for the motor responsive to a comparison value obtained by comparing the measured transition number with the predetermined transition number.

Abstract: Drive circuit for a blower motor employs a microprocessor control element, a controlled rectifier to provide DC power at a controlled rail voltage, and an inverter employing a pair of switching transistors arranged as a bridge inverter or half-bridge inverter. The drive circuit operates over a range of blower speeds and varies both the frequency and amplitude of bipolar pulses that are applied to the blower motor armature.

Abstract: The synchronizing circuit of a digital drive system of an electric motor is configured to function in a closed loop or in an open loop mode by adding a minimum number of elements to the normal scheme of a closed loop synchronizing circuit. In practice, by adding only one programmable register and a pair of two-input de-multiplexers, the system is able to automatically switch from one mode of operation to the other mode. The programmable open loop mode permits compensating for the phase angle between the current flowing through the windings and the drive voltage applied thereto, as in case of a voltage mode driving.

Abstract: A method and apparatus for improving the efficiency of an induction motor used in fluid pump and blower applications including a controller that reduces the flux generated by the motor at less than maximum motor loads.

Abstract: A control apparatus for variably controlling a speed of an induction motor includes a voltage generator, adders, a rotating speed calculating device, a rotating direction detecting device, and a multiplier. The voltage generator is operated for a predetermined period of time at the start or restart of the induction motor to cause self-excited oscillation in a control system including the voltage generator, the induction motor and the PWM inverter. The rotating speed calculating device obtains the rotating speed data, and the rotating direction detecting device detects the rotating direction of the induction motor based on the .alpha.- and .beta.-axis components, on the stationary coordinate, of the primary current of the induction motor. And, the PWM inverter is started based on the obtained rotating speed data and rotating direction.

Abstract: A power circuit of an air conditioner for electric vehicles includes a high voltage power source, a drive circuit for driving a compressor motor, and a capacitor connected between a positive side coupling and a negative side coupling to the high voltage power source. The power circuit comprises a diode provided in the positive side coupling and a switching element provided in the negative side coupling. The capacitor is charged by the pulsed operation of the switching element which is controlled by an operation control device. The capacitor may be quickly charged in a stable condition without burdening the devices in the power circuit. Consequently, the air conditioner may be quickly started.

Abstract: A method for the field-oriented control of an induction motor (2) by means of a frequency converter (1) is disclosed, in which method a transformation angle (.delta.) is determined by estimation and is corrected in dependence on a rotational speed (.omega..sub.mR) of a rotor flux vector (i.sub.mR) or of the induction motor (2) and/or in dependence on a delay time (T.sub.del). In this connection it is desirable to improve the control behavior. To that end, the transformation angle (.delta.) is corrected a second time to compensate for a phase shift in the frequency converter (1).

Abstract: A position control and monitoring circuitry is provided for an electric motor having a plurality of coils and a movable element. A drive circuit generates a square wave drive signal of variable mark/space ratio to drive the coils to position the movable element. A monitoring circuit modulates square wave transitions at a sub-harmnonic of the drive signal frequency and generates a monitoring signal for injection into the coils. A sensor senses the monitoring signal from the coils to determine the position of the movable element. A difference circuit drives the drive circuit with a difference between an input signal and an output signal of the sensor.

Abstract: A method and apparatus for starting a motor drive into a rotating motor, the method including determining an initial search frequency and search current wherein the current is less than a rated drive current, providing a d-axis flux generating current to the motor at the search frequency and at a magnitude equal to the search current, monitoring a q-axis flux error, decreasing the search frequency until the d-axis flux error is less than a threshold value, thereafter increasing the search current to the rated drive current and, after a flux-up period, providing both q-axis torque producing current and d-axis flux producing current to the motor.

Abstract: A method and apparatus for detecting the presence of a ground leakage path in an electric motor system including an alternating current (ac) electric motor coupled for receiving electric power from a switching inverter of the type having, for each phase of the motor, a pair of serially connected electronic switching devices connected between relatively positive and negative direct current (dc) voltage buses with the switching devices being alternately gated into and out of conduction for providing switched electric power to the motor. The inverter includes a current detector for detecting current in the relatively negative voltage bus. The method comprises initially applying a gating pulse each time the motor is energized to the switching device of each phase connected to the negative voltage bus and identifying a ground leakage path when such gating pulse produces current at the current detector.

Abstract: A power steering apparatus has a flow amount detecting sensor for detecting an actuating oil flow amount on the exit side of an actuator operated by an actuating oil pressure generated by a hydraulic pump, and a control circuit for controlling the rotation of the motor for driving the hydraulic pump. The power steering apparatus has a flow amount variation detecting sensor for detecting a variation amount of an actuating oil flow amount on the exit side of the actuator and a control circuit for controlling the motor rotation on the basis of the variation amount. This is to compensate for the decrease in the flow of oil to the actuator caused by an expansion of a hose between the pump and the actuator.

Abstract: A motor controller for a single phase induction motor (SPIM), wherein the SPIM is driven by a square wave above or below rated frequencies. The square wave may be shaped by introducing one or more notches to eliminate or suppress undesirable harmonics, to reduce the amplitude of the fundamental, to provide desirable voltage control, or to provide desirable voltage to frequency control. The control topology may include switches, main winding taps and switchable capacitors to accommodate selection between line and square wave driving, temporary capacitance increases, or other advantages.

Abstract: A power control system in combination with a three-phase AC motor coupled to a water pump enables the operation of the motor at speeds up to 10,800 RPM so as to provide improved pumping capacity with a smaller motor and smaller pump. The control system supplies AC power to the motor with a frequency of the power being increased at a first high rate up to a frequency at which pump pressure is about equal to a value at which water is being pumped from the outlet pipe of the pump. Thereafter, AC power frequency is increased to the second, slower rate up to a maximum operating frequency of the motor. During the time that frequency of the AC power is being increased, motor current is continuously monitored and compared to a maximum allowable current. If monitored current exceeds allowable current, the frequency of operation is decreased until monitored current is less than the allowable current. Thereafter, frequency is again increased so long as monitored current is less than allowable current.

Abstract: In a multiphase motor driver, each phase current is controlled by the ratio of measurements across a common sense element. By utilizing the same sense element for each phase, inaccuracies which result from the variance among multiple sense elements can be eliminated. The individual phase currents are controlled from a common clock generation device. By appropriately controlling each of the phase currents to assure that only one of the phase currents is flowing through the sense element at the time of measurement, the measurement is assured to be dependent on the individual current and the parametric value of the sense element only. Thereby, the control of the phase currents, via the ratio of the measured values across the common sense element, is independent of the parametric value of this common sense element.

Abstract: A feedback control regulator including a regulated device, a sensor for providing a feedback signal representing a characteristic of the regulated device, and a reference signal. An interpolator provides mathematically manipulated feedback and reference signals and a summing function responds to the mathematically manipulated feedback and reference signals for providing and error signal. In particular, the feedback signal is augmented by 2x and the reference signal is augmented by 2x plus 1. A controller responds to the error signal for adjusting the characteristic of the regulated device.

Abstract: An electric current compensation circuit for use with a multiple-phase burshless motor to reduce ripples in the output torque is disclosed. It contains a plurality of electric current compensation loops each for a respective phase winding and each of the electric compensation loops contains: (a) a first input for receiving a line current from the driver; (b) a second input for receiving the compensation current from the motor sensor; (c) a forward rectifying circuit for forwardly rectifying the line current and the compensation current; (d) a reverse rectifying circuit for reversely rectifying the line current and the compensation current; and (e) a summation circuit for summing the forwardly rectified compensation current and the reversely rectified compensation current and outputting a synthetic current to a phase winding of the motor.

Abstract: A commutation control strategy for eliminating torque ripple and noise from a brushless motor which has a plurality of motor phases connected in a bridge, each phase having a top switching device provided between a phase winding and a positive voltage supply and a bottom switching device provided between the phase winding and a less positive voltage supply in which following commutations of the motor, when the current flowing in a first phase is decaying towards zero and the current in a second phase is rising from zero, the switching devices are operative between a state in which the current flowing in the first phase is caused to decay at a first rate, and another state in which the current flowing in the first phase is caused to decay at a second rate which is lower than the first rate so that the rate of decay of the current in the first phase substantially matches the rate of rise of the current in the second phase.

Abstract: The invention concerns an improved system for windshield wipers in vehicles. An induction motor is used, in which speed is accurately controlled by controlling frequency of power supplied to the motor. The induction motor may be of the consequent-pole type, which ordinarily does not produce sufficient torque. Addition of (a) auxiliary tooth slotting and (b) skew has raised the torque produced to acceptable levels.The invention includes a control system, which senses excess load on the motor, which occurs as the windshield dries, and reduces motor speed, subject to a minimum, in response.

Abstract: A motor rotational speed control apparatus is constructed by a control unit for performing an instruction to accelerate a rotational speed of a motor, an instruction to decelerate, or an instruction to maintain a rotational speed, a driving unit for driving the motor in accordance with an instruction outputted from the control unit, and first and second wires for transferring the instruction of the control unit to the driving unit. The control unit shows the instruction by a combination of signal levels of a first signal and a second signal and transmits the first and second signals to the driving unit through the first and second wires, and the driving unit drives the motor in accordance with the combination of the signal levels of the first and second signals.

Abstract: A disk drive including firmware for overcoming stiction and breaking free the heads of a disk drive which may adhere to the disk surface when the disk is at rest. Upon start-up of the disk drive, if stiction at the head/disk interface occurs, the voltage to the spindle motor and/or actuator motor may be rapidly fluctuated so as to cause a pulsing of the spindle motor and/or actuator motor. Pulsing both the spindle motor and actuator motor creates forces in a plurality of radial directions to allow the head(s) to break free from the disk(s) in the direction of least resistance. Moreover, as the resonant frequency of the spindle motor varies depending on the number of heads that are stuck, the firmware pulses over a range of frequencies including the various resonant frequencies of the spindle motor corresponding to various numbers of heads stuck.

Abstract: An inverter control system for operating an induction motor calculates the primary magnetic flux vector and instantaneous torque value from the primary terminal voltage and primary current of the motor and produces a voltage vector to be delivered to the PWM inverter depending on the deviations of primary flux vector and instantaneous torque value from their command values and the phase angle of primary flux vector, with the switching of voltage vector being controlled so that the PWM inverter operates in a prescribed range of switching frequency irrespective of the period of calculation of the primary flux vector and instantaneous torque value. Setting the upper limit of switching frequency reduces the heat generation of the PWM inverter, allowing it to suffice with a smaller cooling device, and setting the lower limit of switching frequency reduces the magnetic noise and torque fluctuation of the motor.

Abstract: In a motor drive circuit, the collector-emitter paths of two npn-type transistors are connected in series between a power line and ground, and the junction between the two transistors is connected to a motor coil. A control circuit feeds a control current to the base of the transistor connected to the power line so that this transistor supplies a drive current to the motor coil. A current mirror circuit is provided which is constituted of two pnp-type transistors whose emitters are connected to the power line, and the base and collector of the input-side transistor is connected to the control circuit through a diode. The base of another pnp-type transistor is connected to the cathode of the diode, and the emitter of this transistor is connected to the collector of the output-side transistor of the current mirror circuit and to the base of the transistor connected to the power line.

Abstract: A control system (100) for a five-phase brushless DC motor (102) including a stator having five windings and a rotor (116) mounted for rotation relative to the windings (114). The windings (114) are adapted to be electronically commutated in response to the rotary position of the rotor (116). The control system (100) includes a sensing circuit (106) to sense the rotary position of the rotor (116) using an optical or magnetic sensor or the back electromotive force voltages in the windings (114). Electronic switches (112) control the flow of current through the windings (114) in response to control signals generated by a control circuit (110) in response to the rotary position of the rotor (116). The control circuit (110) includes start-up logic to start the motor (102).

Abstract: To control the output from an induction motor with a main winding and an auxiliary winding with multiple taps, varying output stages of the motor are adjusted by the activation of the auxiliary winding or one of its part-windings. According to the invention, the coarse adjustment of the power to be output by the motor is effected by the selection of a certain output stage and a repeating digital m-bit keying pattern generated simultaneously for the purpose of fine adjustment, so that the motor is driven alternately at the set output stage and the next higher or next lower output stage as a function of the sequential logic values of the keying pattern. By means of the process complying with the invention, precise power control is possible which can be used to advantage for the adjustment of output.