Abstract: A method for controlling a variable speed drive arranged for powering an electric motor, the variable speed drive comprising a power part and a control part. The method comprises a preliminary phase of storing a set of predetermined levels of flux of the electric motor. Then, during a current phase, the method comprises selecting a level of flux from among the set of predetermined levels of flux and controlling the power part of the variable speed drive based on the selected level of flux as reference value.

Abstract: A motor control system for induction-type capacitor-start AC electric motors having starting and run windings starts the electric motors on AC power then, without stopping the motor, switches to using a variable-frequency motor drive (VFD) configured with a maximum power point tracking method to run the motor from solar power. In particular embodiments, the MPPT method is adapted to reduce power consumed by the motor by reducing frequency and voltage provided by the VFD when available solar panel power is insufficient for full power operation, and to increase frequency and voltage provided by the VFD when available solar panel power is greater than power absorbed by the motor.

Abstract: An electronic speed control system and method is disclosed to control motors that power a load. The electronic speed control system is configured to monitor the motors, accept user commands for the motors, to process these inputs along with various motor parameters and/or models, and to generate motor commands to send to the motors. A field oriented control method continuously monitors voltages and currents from each motor phase; accesses the motor parameters; uses a model of the motor to calculate motor rotor flux, angle and speed based on the stator voltages and currents and the motor parameters; and generates motor commands for controlling the motor based on the user commands and the calculated values. The electronic speed control system can also control external accessories, and/or communicate with external applications which can include a motor identification system that can provide the motor parameters and model for the motor.

Abstract: An electric drive system for a three-phase PM electric machine. The drive system includes a split stator winding for each phase of the machine including a first winding section and a second winding section, and an inverter circuit including a pair of inverter switches for each phase, where the pair of inverter switches for each phase is electrically coupled to the first and second winding sections for that phase in the stator. The drive system also includes a switching system including a switch circuit, where the switch circuit includes a plurality of switch assemblies for switching between a full winding control mode and a half winding control mode, where each switch assembly includes a first AC switching device and a second AC switching device, and where each switch assembly is electrically coupled to the pair of inverter switches and the first and second winding sections for a particular phase.

Abstract: An electric motor (10) has a stator (20) having a number S of stator poles (21, 22, 23, 24, 25, 26); a rotor (40) having a rotor magnet (40?), which rotor magnet (40?) has a number R of rotor poles (41, 42, 43, 44, 45, 46), R being equal to S, and the rotor (40) or the stator (20), or both, exhibiting a magnetic asymmetry. The asymmetry facilitates startup. The electric motor has a single-phase winding arrangement (30) with first (11), second (12) and third (13) terminals. Current can be made to flow, selectively, from either the first or the second terminal, through certain coils, to the third terminal (13). There is an output stage (50), preferably an H-bridge. The W total coils comprise a plurality of subgroups (TG1, TG2) of coils. A method for current flow through an electric motor utilizes these sub-groups (TG1, TG2) for current flow.

Abstract: A double wound rotor type motor with a constant alternating current or direct current power supply input and a control method thereof is disclosed. The wound rotor type motor includes: a stator in which a coil directly connected to a single phase grid power supply or a direct current power supply is wound; a rotor that is rotatably supported in the stator; a power conversion device that is attached to the rotor and controls a rotor current without connection of a separate external power supply; and a control circuit that is connected to the power conversion device and controls the power conversion device.

Abstract: This disclosure relates to a control system for driving a motor. The motor may include a cut-out circuit. The control system may include a buck-boost circuit to limit the rate of change of an output voltage before the output voltage is applied to operate the motor.

Abstract: The method for activating an asynchronous motor comprising at least two windings is provided, in order, for the purpose of a change in the rotational speed, to connect a first winding and at least one second winding by way of at least two electronic switches. On switching, both switches are opened for one or more time intervals in order to avoid current peaks.

Abstract: A single-phase AC motor control circuit for a dryer, including a starting control unit, a first drive circuit, a bidirectional triode thyristor BCR1, a second drive circuit, and a bidirectional triode thyristor BCR2. The bidirectional triode thyristor BCR1 is serially connected to a motor starting winding, and a starting capacitor, and then to a utility power AC input. The starting control unit is connected to a control end of the bidirectional triode thyristor BCR1 via the first drive circuit. The bidirectional triode thyristor BCR2 is serially connected to an electrically heated strip, and then to the utility power AC input. The starting control unit is connected to a control end of the bidirectional triode thyristor BCR2 via the second drive circuit. The first drive circuit is interlocked with the second drive circuit.

Abstract: The present invention relates to a single phase induction motor, and more particularly, to a single phase induction motor, wherein a variable resistance element which can change a winding number of a main winding or an auxiliary winding capable of producing a magnetic field at the time of starting is connected in parallel to some portion of the main winding or the auxiliary winding. A single phase induction motor including a stator composed of a core, a main winding and an auxiliary winding, and a rotor rotated by a mutual electromagnetic force by the stator comprises a resistance variable element connected in parallel to some portion of the main winding.

Abstract: Starting device for electric motors provides a circuit including: a first branch connected at one end to a common point and at the opposite end to the start winding of the motor, whereon a starting capacitor, a resistor and fixed contacts of a relay are inserted in series respectively; a second branch in parallel with the first branch, connected at one end to the common point and at the opposite end to the main or run winding of the motors whereon the coil of the relay is inserted; a third branch in parallel with the branches and, connected at one end to the common point and at the opposite end to the start winding of the motor, whereon a run capacitor is installed, this common point being connected to the common connector of the motor via the power supply line.

Abstract: An electronic relay for single phase induction motor, the electronic relay including a triac located between a start winding and a start capacitor of the single phase induction motor to control current flow of the start winding and an induced voltage detection circuit to detect an induced voltage of the start winding proportional to an angular velocity of the motor. The electronic relay is adapted to detect a zero-point voltage of a motor line voltage before start of the motor and to calculate an acceleration torque during start of the motor. The electronic relay is programmed to turn on the triac when the zero-point voltage of the motor line is detected and to turn off the triac when the acceleration torque begins decreasing.

Abstract: The invention relates to a method (19) for starting an electric single-phase induction motor (1), wherein during a start-up interval of the start-up cycle for starting said electric motor (1), the frequency (fref) of the electric current for driving said electric motor (1) is set to a first frequency (fstart), and later to the operating frequency (frun) of the electric motor (1), wherein the first frequency (fstart) is higher than the operating frequency (frun).

Abstract: The method for initially starting the motor improves the reliability to the start of the motor. In particular, even though the external load is at more than a predetermined level, a rotor located at an arbitrary angle can be aligned to an accurate initial position. Moreover, it can prevent the damage of the motor or the damage of the electronic device where the motor is installed. In order to initially align the rotor of the motor, a position on a stationary coordinate system, to which an alignment current of a rotation magnetic field is applied, is varied.

Abstract: An electronic starter device for an electric motor including a first terminal connected in use to a mains voltage source selectively activatable by means of control means to feed respective starter and run windings of the electric motor; switch means arranged in series between the voltage source and the starter winding to selectively feed the starter winding; generating means of a first low voltage potential (V1) directly connected to the feeding terminal; timer means including at least one capacitor and means for selectively charging the capacitor by means of at least one first resistor; first driving means for activating the switch means; and second driving means for activating the first driving means, the latter being arranged logically in a cascade with respect to the second driving means, which are activated by means of the timer means.

Abstract: An inverter apparatus is for correcting deviations among current detectors of a three-phase motor. The inverter apparatus includes bidirectional switching elements that have on and off states in the cases in which there are 1 and 0 mean on- and off-states. The states are alternately repeated by controlling the switches, and measurement for correcting the deviations among the current detectors are obtained in the state Currents have the same amplitude flow on a U phase and a V phase. In the state of normal use, the inverter apparatus is operated by correcting detected current values based on the measurement data.

Abstract: The present invention relates to a device (20) and a method for sensorless measuring a mechanical rotor frequency of a rotor (6) of an asynchronous machine (40), wherein the rotor (6) has a predetermined defect and the asynchronous machine (40) has a fixed number of pairs of poles. The asynchronous machine (40) comprises a current determination unit (2) for determining a stator current of the stator (7), wherein the stator current has a stator frequency. A processing unit (3) forms a stator current spectrum of the stator current. An analyzing unit (4) analyzes the stator current spectrum and determines an inverse peak (26) and a corresponding inverse frequency in the stator current spectrum, wherein the inverse peak (26) is the peak having the second highest amplitude in the stator current spectrum in the frequency range of the stator frequency.

Abstract: The present invention relates to a single phase induction motor, and more particularly, to a single phase induction motor, wherein a variable resistance element which can change a winding number of a main winding or an auxiliary winding capable of producing a magnetic field at the time of starting is connected in parallel to some portion of the main winding or the auxiliary winding. A single phase induction motor including a stator composed of a core, a main winding and an auxiliary winding, and a rotor rotated by a mutual electromagnetic force by the stator comprises a resistance variable element connected in parallel to some portion of the main winding.

Abstract: A motor start circuit for an AC induction motor employs a DC relay whose NC contacts are placed in series with the start capacitor. A half full-wave rectifier arrangement has an AC input connected to the junction of the relay switch and the start capacitor, and DC outputs applied across the relay actuator coil. In the event of intermittent application of power to the motor, any residual charge on the start capacitor will feed current to the actuator coil to hold the relay switch open until the residual charge has decayed sufficiently, to avoid damage to the motor from capacitive discharge. A high magnetic retentivity core can be used to hold the relay off for sufficient time for stored energy to dissipate.

Abstract: An electronic starter device for an electric motor including a first terminal connected in use to a mains voltage source selectively activatable by means of control means to feed respective starter and run windings of the electric motor; switch means arranged in series between the voltage source and the starter winding to selectively feed the starter winding; generating means of a first low voltage potential (V1) directly connected to the feeding terminal; timer means including at least one capacitor and means for selectively charging the capacitor by means of at least one first resistor; first driving means for activating the switch means; and second driving means for activating the first driving means, the latter being arranged logically in a cascade with respect to the second driving means, which are activated by means of the timer means.

Abstract: FIGS. 4A and 4B are principle diagrams for correcting deviations among current detectors of a three-phase motor 19 in an inverter apparatus of the present invention, which includes bidirectional switching elements 13 to 18. FIG. 4C shows on and off states of switches in the cases of FIGS. 4A and 4B, in which 1 and 0 mean on- and off-states, respectively. The states shown in FIGS. 4A and 4B are alternately repeated by controlling the switches, and measurement for correcting the deviations among the current detectors are obtained in the state shown in FIG. 4B. Specifically, in FIG. 4B, currents having the same amplitude flow on a U phase and a V phase. Accordingly, a difference in the measured data represents a difference in performances of the current detectors. In the state of normal use, the inverter apparatus is operated by correcting detected current values based on the measurement data.

Abstract: A brushless DC motor operated by a microcontroller has a unique pole construction that enables it to reliably start and operate as a unipolar device so that a reduced number of electronic power switches can be used to reduce cost and complexity. The microcontroller calculated rotor position to eliminate the need for a separate sensor and thereby further reduce manufacturing cost.

Abstract: An induction motor system comprising an induction motor, equipped with a heat recovery and water pumping apparatus and an apparatus for controlling the electrical efficiency and resulting heat generation of the induction motor. The motor is adapted to be coupled to an AC source for supplying an AC signal. The controlling apparatus includes a switching device, user controls and optional inputs. The switching device is connected in series with the motor and is operative in either a high impedance state wherein significant current flow through the motor is prevented or a low impedance state wherein current flow through the motor is substantially undisturbed. The user controls provide motor operational input signals. The optional inputs provide setpoint and sensed water temperature input signals.

Abstract: A synchronous induction motor has a stator having a main winding and an auxiliary winding; a rotor having a yoke, a permanent magnet embedded in the yoke and a secondary conductor provided in the vicinity of periphery of the yoke; and a starter. The starter has a starting capacitor connected in series with the auxiliary winding of the synchronous induction motor, and a switching unit to open/close a circuit from the starting capacitor to the auxiliary winding. The switching unit closes the circuit from the starting capacitor to the auxiliary winding when the synchronous induction motor is at rest, and opens the circuit after the synchronous induction motor is started. The synchronous induction motor is highly efficient and easy to re-start with low power consumption. The electric hermetic compressor equipped with the synchronous induction motor can perform with the similar effects.

Abstract: An electric machine assembly having an electric machine. The electric machine can include a first speed circuit and a second speed circuit. In some constructions, both speed circuits can be of a permanent split capacitor design. At least one of the speed circuits can include a switch that is controlled by the controller to limit current through an auxiliary circuit of the unused speed circuit when certain conditions exist.

Abstract: An electric drive includes a rotatable shaft, a first drive member, and a second drive member, and is supplied with power from a controller. The controller is operable to supply a first power from a power electronics converter, and a second power that is line power. Supplying the first power individually to the first drive member results in a first shaft speed and first output torque, supplying the second power individually to the second drive member results in a second shaft speed and second output torque, and supplying the first and the second drive members with power at the same time results in a third shaft speed and a third output torque.

Abstract: Apparatus for driving a three-phase compressor assembly from a single-phase electrical power supply having first and second power lines, said three-phase compressor assembly comprising a compressor having a rotatable shaft, an electrical motor having a rotatable shaft coupled to the rotatable shaft of the compressor, the electrical motor having at least first, second and third motor windings and having at least first, second and third terminals connected to the first, second and third windings, means adapted to connect the first and second power lines of the single-phase power supply to the first and second terminals and a torque augmentation circuit for injecting current into the third terminal and including a capacitor and an electrical component in series with the capacitor, said electrical component having resistive characteristics and having means for essentially interrupting the current being injected into the third terminal.

Abstract: A driving circuit for improving starting of a hybrid induction motor and its method includes a capacitor for operation electrically connected between a main coil and a auxiliary-coil, and a starting and current cutting-off means electrically connected with the capacitor for operation, applying a high starting current to a motor in starting, and cutting off the starting current when the motor is operated at a synchronous speed after the starting, so that a satisfactory starting characteristic can be obtained by increasing output under a low voltage state in starting, and effective operation can be performed by decreasing output under a normal operation state after the starting is completed.

Abstract: There is provided a voltage-controlled electronic relay for starting a single-phase induction motor, which includes: a power supply unit 310, configured of a bridge diode BD, for supplying power to circuit elements of the starting relay when AC power of the induction motor is turned on; a triac 306 for applying the AC power to a starting coil W3 of the induction motor or cutting off the AC power; a signal input unit 322 for sensing a voltage induced to the starting coil; a hysteresis unit 324 for outputting an ON control signal at the initial starting stage, generating an OFF control signal for turning off the switch when the induced voltage sensed by the sensing element reaches a predetermined OFF reference voltage, and generating the ON control signal for turning on the switch again when the induced voltage becomes lower than a predetermined ON reference voltage during a normal operation period; and a triggering unit 330 for turning on the switch according to the ON control signal of the hysteresis unit and

Abstract: A ventilator having a muting device includes a central processing unit, and a fan motor. The fan motor is connected to a start capacitor which is electrically connected to a temperature sensing circuit which is electrically connected to the central processing unit, so that the start capacitor can indicate a signal on a panel of the ventilator, so as to control a rotational speed of the fan motor. Thus, the operation state of each part of the ventilator is indicated on the panel of the ventilator clearly to facilitate inspection of the user, so that the user can control the rotational speed of the fan motor to a proper value, thereby reducing the noise during operation, so as to achieve a muting effect.

Abstract: The invention prevents the voltage change dv/dt occurring at an inverter from directly igniting a semiconductor braking switch and short-circuiting the inverter during operation. In a dynamic brake circuit which absorbs energy by brake resistor 15 upon igniting semiconductor braking switch 14 and short-circuiting power supply lines of the motor 10 when braking motor 10, which is driven by an inverter part comprised of three-phase AC power supply 1, three-phase bridge rectifier circuit 3, smoothing capacitor 6, and semiconductor switching devices 7, high resistor 20 is disposed between the anode side of the smoothing capacitor 6 and the anode side of the semiconductor braking switch 14, whereby snubber capacitor 17 of snubber circuit 18 connected in parallel to the semiconductor braking switch 14 is charged via this high resistor 20 prior to operation of the inverter part.

Abstract: A drive system including a rectifier, a high-frequency filter, a static inverter and an induction motor is driven without energy stores and fed by the single-phase mains, in which the use of an envelope generator with a mains-synchronous, preferably sinusoidal signal causes a preferably sinusoidal envelope to be sign-superimposed on the static inverter output signal, thus preventing inadmissible current overshoots in the single-phase mains. Possible fluctuations of the intermediate circuit voltage are thereby compensated. The advantageous operating frequency of the static inverter may be adjusted automatically by a PLL control circuit in that the phase shift between intermediate current and the envelope signal is evaluated. The advantageous operating frequency may be gained by adding a given frequency difference to the rotational speed of the motor. The envelope directly represents a projection of the variation of the voltage of the single-phase mains.

Abstract: A phase shifting network for an inductor motor is provided. The network includes a resistor connected in series with each motor phase coil of a pair of motor phases. The network further includes a capacitor connected between the motor phases. The inventive phase shifting network produces current and voltage waveforms within the motor phase coils that are smoother, more equal, and less subject to harmonic distortion as compared to the waveforms generated by conventional phase shifting networks.

Abstract: A motor system utilizes a master three-phase induction motor driven by a single-phase power supply which the motor has six-windings connected in a symmetrical double DELTA or double WYE configuration with appropriate running capacitors to provide when the motor is running a balanced three-phases of voltage potentials. The potentials have been tapped off to run satellite three-phase induction motors.

Abstract: An induction motor system operable in a wet environment comprises an induction motor and an apparatus for controlling the speed of the motor. The motor is adapted to be coupled to an AC source for supplying an AC signal. The motor includes a rotor having rotor laminations. The reflected rotor resistance over reflected rotor reactance ratio of the motor is adjusted to be greater than one. The controlling apparatus includes a switching device, user controls, controller means and isolation means. The switching device is connected in series with the motor and is operative in either a high impedance state wherein significant current flow through the motor is prevented or a low impedance state wherein current flow through the motor is substantially undisturbed. The user controls provide motor speed input signals.

Abstract: An electric motor and its controller are specially adapted for variable speed applications. The stator of the motor has its main windings controlled by triacs. The triacs are placed to allow the main windings to operate in series at low speed and in parallel at high speeds. The firing delay of the operating triacs is controlled in both series and parallel winding operations to aid in smooth operation of the motor. The auxiliary winding is preferably left uncontrolled to contribute a regular sinusoidal component to the windings power at all times. The controller receives the speed command and figures firing delay and outputs triac control pulses at one of a plurality of settings to bring the motor to the selected speed. In this manner a simple, inexpensive, and continuously variable speed motor may be realized with good performance characteristics.

Abstract: A start circuit for a single-phase AC motor controls the current through the start or auxiliary winding based on time rate of change of voltage or current, or based on the current or voltage dropping or rising some fraction from inrush value, i.e., to 50% of initial start current or to 150% of initial start voltage. The circuit can also include a default timer to time out the start current after some preset period between 300 and 1000 milliseconds.

Abstract: A motor start switch includes a temperature responsive resistor element and a cutout switch electrically connected in series with a start winding of an electric motor. The cutout switch is in thermal contact with the temperature responsive resistor element so that heat from the temperature responsive resistor element is transferred to a bimetal element in the cutout switch, causing the bimetal element to open the switch. Heat from a motor overload protector provides heat to maintain the bimetal element in an open position. As heat to operate the temperature responsive resistor element is obtained from existing circuit elements, the efficiency rating of the motor is unaffected.

Abstract: A three phase AC motor which rotates at the synchronous speed determined by the number of poles of its main stator winding and the frequency of the AC input to it, which does not need any exciter machine or brushes to provide its DC field current, but has an internal, but independently adjustable excitation system to supply its field current. The internal excitation system consists of an auxiliary winding on the stator which is additional to the main power winding, another auxiliary winding on the rotor besides the main DC field winding, a diode rectifier circuit on the rotor from which the DC field current is supplied by rectification of the induced currents in the rotor auxiliary field. The field current adjustment can be made by adjustment of the input to the stator auxiliary winding. This can be done independently by eliminating any magnetic coupling between the main and auxiliary circuits.

Abstract: For a three-winding motor, a starting capacitor bank provides balanced currents in the windings, a high starting torque, and unity power-factor current in the single-phase supply line. A run-capacitor bank provides full-load balanced currents and a leading power-factor in the single-phase supply line. The method is applicable to a star or wye winding connection, to a delta winding connection, and to a Semihex.TM. winding connection.

Abstract: A braking circuit for braking an electric motor having an armature and run and brake windings, which includes a switching circuit disposed between a source of electrical power and the run winding, this circuit being operable to disconnect the run winding from the source of electrical power. The braking circuit further includes a switching mechanism operable to connect the brake winding in order to brake the electric motor. The switching mechanism preferably connects the brake winding after a predetermined period of time has elapsed from the disconnection of the run winding. This braking circuit can be used in a saw for braking the saw's blade.

Abstract: An improved method of starting three-phase and three-winding induction motors from a single phase supply reconfigures the 6 accessible windings of a standard induction motor into first an optimal starting configuration which, for example, may reduce starting torque or starting current and then an optimal run configuration. One example of a run configuration is a normal delta along with an inverted delta; another example is a (voltage phasor half-hexagon) run configuration where the windings are all series connected with 120.degree. phase differences.

Abstract: Method for controlling the speed of a single-phase asynchronous induction motor, the stator of which is equipped with a main winding (BP) and an auxiliary winding which consist of half-windings (B1, B2) which are magnetically coupled and wound in opposite directions, in which method the main winding is powered directly using an AC source and the auxiliary winding is powered using a current delivered by a full-wave rectifier and using two switching devices (T1, T2), so as to generate in the auxiliary winding a current which is phase-shifted by 90.degree.. The method consists in varying the motor torque by altering the time that at least one of the switches spends closed/open.

Abstract: A capacitively powered motor having a power switching circuit adapted to be connected between a power source and its winding for selectively energizing the winding to generate a magnetic field which causes a rotating assembly to rotate. A position sensing circuit provides a position signal representative of the position of the rotating assembly and a commutating circuit controls the power switching circuit to commutate the power switching circuit at a commutating angle and at a substantially constant duty cycle to achieve a desired rotating speed of the rotating assembly. The commutating circuit varies the commutating angle in response to the position signal to maintain the substantially constant rotating speed of the rotating assembly. As result, the efficiency of the motor is varied to maintain the substantially constant rotating speed.

Abstract: A motor whose stator is equipped with a main winding (DP) and with an auxiliary winding which consists of two half-windings (B1, B2) that are wound in opposite directions and is supplied through a full-wave rectifier (GR) and by means of two commutating switches (T1, T2) controlled by a control circuit (COM) which alternately closes the switches at a frequency equal to the frequency of the supply voltage. The motor comprises, in parallel with the half-windings, at least one device (DAP) which limits the voltage across the terminals of the switches when they are opened, to a value higher than the supply voltage.

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 speed control apparatus for determining and controlling the speed of rotation of a rotor in an AC motor. The motor includes a stator having main and auxiliary windings. Main and auxiliary winding controllers control the operational input signals supplied to the main and auxiliary windings by a signal generator. A pulse generator is connected to the main winding for providing a test pulse during a speed measurement operation. The test pulse magnetizes a portion of the rotor which induces a feedback EMF signal in the auxiliary winding. A feedback sensor circuit receives the feedback signal and forwards it to a microprocessor. The microprocessor calculates the rotational speed of the rotor based on the feedback signal.

Abstract: The invention relates to a single-phase induction motor comprising a main winding, an auxiliary winding which is arranged so that an electrical angle of the auxiliary winding is different from that of the main winding, a plurality of driving capacitors which are connected to the auxiliary winding, a relay for controlling on/off of the driving capacitor in response to the driving load, and a rotor having apertures on the gap side of the slots. The invention further relates to a rotor assembling apparatus comprising a bush to which a rotor core assembly is inserted for die-casting, wherein a clearance between said bush and said rotor core assembly is narrower to the extent that said rotor core assembly can be taken out after die casting; and a core band having a clearance between the core band and the bush in the circumferential direction of said bush, said core band is engaged into said bush so that movement in the axis direction is restricted.

Abstract: An electrical circuit for controlling start windings in induction motors of various sizes or horsepowers providing a broad range of application. The circuit for controlling start winding switching measures the current through both the start and run windings of the motor allowing the use of a single solid state device in the circuit. This combined current develops a voltage across a resistor which is used to gate on the solid state device when the voltage exceeds a threshold level. By using the solid state device in combination with the special resistor, a motor start switch is formed which can be used to start a wide range of dual voltage motors.

Abstract: The present invention involves a control system for a motor having a main winding and an auxiliary winding disposed on a stator. A microprocessor determines the phase difference between the line voltage and the voltage between the main winding and the auxiliary winding to determine the rotational status of the rotor. In a moving rotor, a measurable phase difference exists. This phase difference can be measured by monitoring the zero crossings of the respective voltages. One method of measuring the phase difference is to check the logic state corresponding to the voltage between the main and auxiliary windings when a predetermined time period has elapsed after a zero crossing of the line voltage. Another method measures the time delay between the zero crossings of the two voltages. The control system of the present invention is particularly adapted for use with single phase AC motors having a main winding and an auxiliary winding disposed electrically out of phase on the stator.