Abstract: At least two asynchronous AC induction electrical machines in parallel connection with the power source are respectively made with the main winding and control winding for operating the electrical machines, wherein the individually driven loading operations of the two electrical machines in cross-interlockingly parallel connection being parallel connected with the power source are led by the changes of individual electrical machine driving loading statuses to appear variable impedance operation so as to change the end voltage ratio between individual electrical machines in cross-interlockingly parallel connections.

Abstract: At least two asynchronous AC induction electrical machines in series connection with the power source are respectively made with the main winding and control winding for operating the electrical machines, wherein the individually driven loading operations of the two electrical machines in cross-interlockingly series connection being series connected with the power source are led by the changes of individual electrical machine driving loading statuses to appear variable impedance operation so as to change the end voltage ratio between individual electrical machines in cross-interlockingly series connections.

Abstract: Method and system are provided for controlling an alternating current (AC) motor via an inverter. The method includes selecting a pulse sequencing method based on a modulation index of the inverter, and providing a voltage to the AC motor based on the pulse sequencing method. The system includes an inverter having a modulation index (Mi) and a controller coupled to the inverter. The controller selects a pulse sequencing method based on Mi and produces a signal based on the pulse sequencing method. The inverter includes a switch network producing a voltage in response to the signal, and the voltage drives the AC motor.

Abstract: An electrically driven mooring includes a winding drum (101), an alternating current motor (103) arranged to drive the winding drum, a frequency conversion unit (104) connected to the alternating current motor, and a control unit (105) arranged to control the frequency conversion unit on the basis of an indicator for tension of the mooring rope. The control unit is arranged to compute a flux space vector for modelling a stator flux of the alternating current motor, to compute a torque estimate on the basis of the flux space vector and a space vector of stator currents, and to use the torque estimate as the indicator for the tension of the mooring rope. Hence, a need for a force sensor on the mooring rope and a need for a speed/position sensor on the motor shaft can be avoided.

Abstract: A motor speed controller and a method of controller a speed of a motor are provided. The system and method include a motor and a motor controller that monitors operation of the motor based on electromotive force (EMF) conditions of the motor. The motor controller cuts a voltage to the motor, measures an electromotive force (EMF) of the motor at a predetermined time after the cutting of the voltage to the motor, and compares the measured electromotive force (EMF) to a table.

Abstract: An autonomous controller allows an AC induction motor to operate over a broad range of AC power supply frequencies by reducing the amount of current supplied to the motor at lower frequencies. The controller detects the frequency of the power supply and switches the supply current on and off during each AC cycle to limit the RMS current to a value that is related to the detected frequency. Alternatively, the controller switches capacitive reactance into the power supply circuit which reduces the current supplied to the motor at lower AC frequencies.

Abstract: A gain equalization device for an AC motor control includes two detection devices, a control process unit, a storage and two multipliers. Each detection device includes a current detector and an A/D converter. The current detectors are configured to detect the respective currents of two phases of an inverter circuit. Current feedback values are detected by the current detectors and converted into the digital signals by the A/D converters. The control process unit is configured to generate a compensation value to adjust the gain unbalance between gains of the detection devices. The storage is configured to store the compensation value. The multipliers are configured to compensate for an actual gain unbalance based on the compensation value stored in the storage and the current feedback values detected by the current detectors.

Abstract: A method of determining a slip estimate associated with an induction motor through analysis of voltage and current signals. A fundamental frequency is calculated from a representation (e.g., complex representation) of the voltage signal, and a saliency frequency is calculated from a representation of the current signal. An estimation of slip quantity is calculated according to a slip estimation function that includes the saliency frequency, a saliency order, the fundamental frequency, a quantity of rotor slots, and a quantity of poles of the motor.

Abstract: Method for operating a delta wound three-phase permanent magnet brushless motor. A transition speed is determined in a quadrant of a speed versus torque curve above which speed continues to increase while current/torque decreases wherein actual phase current can be controlled in a current control modification manner which reduces requested phase current. The modification manner is determined for a quadrant, wherein a controller can use the modification manner to reduce the requested phase current to control the actual phase current when the speed is above the transition speed. The motor is controlled in a quadrant wherein, when the motor has a speed above the transition speed, the controller reduces the requested phase current in the modification manner and the controller supplies the actual phase current to the motor using the reduced requested phase current and using measured phase current of the motor derived from using a single current sense resistor.

Abstract: An apparatus for controlling the drive of an electric motor, having a current detector for detecting the current through an externally connected electric motor; a controller for generating a control signal to control the electric motor on the basis of the current detected by the current detector and the speed command for specifying the rotational speed of the electric motor; wherein the apparatus includes a load estimator for estimating the mechanical load condition associated with the electric motor on the basis of the current detected by the current detector and the speed command, and the controller controls the electric motor current on the basis of the detected current, the speed command and the estimated load condition.

Abstract: A semiconductor device in which the lifetime of mounted components can be prolonged. A cooling system for controlling the temperature of a refrigerant through a heating section and a radiator is provided. The semiconductor device is connected to the cooling system and is cooled. A variation width (?T1) of temperature controlled by the cooling system through the heating section and the radiator is smaller than a temperature variation (?T2) of the refrigerant caused by variations in operating conditions of the semiconductor device (?T1??T2).

Abstract: The present invention employed a motor control device including: current sensors which detect currents in each phase of a three-phase motor; a coordinate conversion device which computes a d-axis actual current and a q-axis actual current in dq-coordinates from phase currents of three phases based on detection values of the current sensors; a voltage instruction computation device which computes a d-axis voltage instruction and a q-axis voltage instruction based on a deviation between a d-axis current instruction and the d-axis actual current and on a deviation between a q-axis current instruction and the q-axis actual current; a target phase current computation device which computes target phase currents for each phase from the d-axis current instruction and the q-axis current instruction; and a current difference computation device which computes, for each phase, a current difference between the phase current and the target phase current.

Abstract: A vector control apparatus for a permanent magnet motor operated in the region of weak magnet field, wherein when the output voltages of the power converter saturate, the phase error command value represented by the difference between the angular position of the reference axis for control and the angular position of the motor magnetic flux axis is generated on the basis of the difference between the q-axis current command value and the detected value of the q-axis current, and the command values for the output voltages of the power converter are corrected by using the phase error command value, whereby a highly responsive torque control with high precision can be achieved.

Abstract: In an inverter system including of an electric-power converter and an ac rotating machine, over-voltage generated in the ac rotating machine is controlled by a low-cost system configuration. The system includes: an electric-power converter; a three-phase ac rotating machine; and a four-core non-coaxial cable, having a ground line and three-phase electric-power supplying lines, connecting the electric-power converter to the three-phase ac rotating machine. One or two capacitors are connected between the ground line and one or two of the electric-power supplying lines, at electric-power supplying terminals on the rotating machine, so that respective capacitances between the three-phase electric-power supplying lines and the ground line are approximately equal to each other.

Abstract: The present invention relates to a parameterization method for a converter (1, 2) of the speed controller type, the said converter (1, 2) being connected to an electrical load (3) by means of an electrical cable (4) comprising at least two conductors, the method consisting in: generating common-mode current on the electrical cable (4) starting from a pulsed voltage comprising a first voltage edge (11, 13) and a second voltage edge (12, 14) delayed by a delay time (T) with respect to the first voltage edge (11, 13), measuring the common-mode current generated, making the delay time (T) between the two voltage edges (11, 12, 13, 14) generated vary, and determining an optimal delay time (T2) starting from a quantity (Ipeak, Ieff) representative of the common-mode current measured for the various values of the delay time (T).

Abstract: As an antilock system for a permanently excited electric motor drive, especially for a steering booster servo drive of a motor vehicle, in the event of a winding short-circuit, an interruption of at least one winding phase (MP1 or MP2 or MP3) of the winding affected by the short circuit is provided, by a separating means (T) triggered by an explosion directly or indirectly by the winding short-circuit. The antilock system advantageously has a separate neutral point connection part (MP) which is especially embodied as a sheet metal moulded part, is to be connected to the winding ends of the electric motor, and contains the winding phases (MP1; MP2; MP3) and the neutral point connection thereof as a single component. The antilock system is purposefully arranged on a front winding head of the electric motor and connected to the winding thereof.

Abstract: A controller and a motor assembly having a controller. The controller includes a first switch assembly in a series configuration with the motor, where the first switch assembly has a first transistor, a second switch assembly in a parallel configuration with the motor, where the second switch assembly has a second transistor, and a control circuit electrically connected to the first transistor and to the second transistor to control the first switch assembly and the second switch assembly to provide a chopped voltage to a motor.

Abstract: An ac motor for high-torque drive has a transformer with a magnetic circuit with a central limb. Either the two ends or the two connected electrodes of the secondary winding of the transformer project at an angle to the longitudinal axis of the secondary winding; an armature rotor dielectrically bridges the two ends or the two connected electrodes, moving parallel to the longitudinal axis. The rotor forms two series-connected capacitors with the two ends or the two connected electrodes. An LC circuit is formed by the two capacitors in series to the total effective inductance of the power source, the electric transformer, the two ends or the connected electrodes and the armature. The impedance of the LC circuit is varied by the frequency of the power source supplying the primary winding of the transformer, in order to push required electric power from the power source to the series LC circuit.

Abstract: Capacitors act as bootstrap capacitors of a high side control circuits. The capacitors are charged in a period in which all of high arm switching devices are non-conductive, so-called in a precharge period. When any of U-phase current, V-phase current and W-phase current is smaller than a negative predetermined value (when an absolute value is larger), it is judged which is the largest value. The low arm switching device is turned on only for a phase corresponding to the current of the largest value and the low arm switching devices of other phases are turned off.

Abstract: A multiphase current supplying circuit includes a converter, an intervening circuit, an inverter, a control circuit and a lightning arrester. A power supply system is connected to the converter with the lightning arrester interposed therebetween, and the ac voltage is rectified. The intervening circuit includes a capacitor and a bypass connected in parallel thereto. In the bypass, a diode, a resister and a capacitor are connected in series, and the direction from an anode to a cathode of the diode corresponds to the direction from a high potential side to a low potential side of the smoothing capacitor.

Abstract: “STATIC FREQUENCY CONVERTER WITH AUTOMATIC FUNCTION FOR OPTIMIZING MAGNETIC FLUX AND MINIMIZING LOSSES IN ELECTRIC INDUCTION MOTORS”, having an automatic function for regulating and controlling magnetic flux in the motor in function of the motor's operating frequency, such that the motor operates with ideal magnetic flux and consequently with less total losses.

Abstract: A drive circuit for a sensored brushless DC motor, which has a rotably mounted rotor hub, comprises four legs. Each leg has a MOSFET and a diode configured to form four individual nodes. A first primary stator winding is coupled between the first and second nodes, while a second primary stator winding is coupled between the third and fourth nodes. A Hall sensor and an associated interface circuit which detects positions of magnets associated with the motor. As a result of the detected position, the drive circuit turns the MOSFETs on and off in a specified manner so as to rotate the rotor hub without the need for a snubber circuit.

Abstract: A technique is provided for controlling operation of motors of different sized or ratings. Components used to apply and interrupt current to the motors may be shared in control devices for the different motors. The components may include contactors or circuit interrupters, and instantaneous trip devices. The components may be sized for the higher rated motors, and be oversized for the lower rated motors. Control circuitry permits the devices to be controlled in accordance with the characteristics of the particular motor to which the devices are applied, providing accurate circuit interruption while reducing the number of different components and component packages in a product family for the various motors.

Abstract: A vector controller of an induction motor capable of correcting the set value of mutual inductance so as to match it to an actual value by additional processing on software without adding any special device. The vector controller (1) of an induction motor comprises a section (3) for determining the correction value of mutual inductance of an induction motor (15) based on the error between a torque operation value calculated using a measurement of the primary current of the induction motor (15) and a torque command value for the induction motor (15) generated at a torque command generating section, and a vector control section (2) for controlling the induction motor such that the generation torque of the induction motor (15) matches the torque command value by using the circuit constants of the induction motor (15) including the correction value of mutual inductance.

Abstract: An object of the present invention is to provide a chattering preventing circuit, a waveform shaping circuit, and a motor drive control circuit including the chattering preventing circuit or the waveform shaping circuit, to provide an FG signal free from noise caused by chattering, without using a hysteresis comparator.

Abstract: A power system that provides power between an energy storage device, an external charging-source/load, an onboard electrical power generator, and a vehicle drive shaft. The power system has at least one energy storage device electrically connected across a dc bus, at least one filter capacitor leg having at least one filter capacitor electrically connected across the dc bus, at least one power inverter/converter electrically connected across the dc bus, and at least one multiphase motor/generator having stator windings electrically connected at one end to form a neutral point and electrically connected on the other end to one of the power inverter/converters. A charging-sourcing selection socket is electrically connected to the neutral points and the external charging-source/load. At least one electronics controller is electrically connected to the charging-sourcing selection socket and at least one power inverter/converter.

Abstract: A system, method, and article of manufacture for determining parameter values associated with an electrical grid in accordance with an exemplary embodiment is provided. The electrical grid has a point of interconnection where the electrical grid is electrically coupled to a power source. The method includes measuring real power at the point of interconnection of the electrical grid to obtain a plurality of real power values. The method further includes measuring reactive power at the point of interconnection of the electrical grid to obtain a plurality of reactive power values. The method further includes measuring a voltage at the point of interconnection of the electrical grid to obtain a plurality of voltage values. The method further includes estimating at least one parameter value associated with the electrical grid utilizing the plurality of real power values, the plurality of reactive power values, and the plurality of voltage values, and a mathematical estimation technique.

Abstract: A solid state soft start controller system has a power supply, an electric motor, a thyristor electrically interconnected between the power supply and the electric motor so as to selectively allow current to pass from the power supply to the phases of the electric motor, a laser diode optically connected to the thyristor, and a controller connected to the laser diode for triggering the laser diode. Separate thyristors are connected to each phase of the polyphase electric motor. Separate laser diodes and associated light pipes connect the laser diode to the separate thyristors.

Abstract: A motor drive unit includes a controller, a voltage inverter, and a speed estimator. The controller is operable to generate at least one command signal for controlling a motor associated with the motor drive unit. The voltage inverter is operable to generate motor drive signals to be applied to the motor based on the command signal. The speed estimator is operable to estimate a speed of the motor when the voltage inverter is not providing the motor drive signals. The speed estimator is further operable to receive two-axis voltage measurements associated with the motor, determine flux angles for the motor based on the two-axis voltage measurements, and estimate the speed based on the determined flux angles.

Abstract: An apparatus for controlling a speed of a fan motor (HIM (Hybrid Induction Motor)) of an air-conditioner extends a speed control range of a fan motor of an air-conditioner by controlling revolutions per minute (RPM) of the fan motor. In order to extend the speed control range of the HIM, an RPM of the HIM is controlled based on a pre-set duty ratio of a switching device electrically connected with the HIM.

Abstract: A single-phase induction motor includes a main winding, an auxiliary winding, a run capacitor, and a subsidiary start device. The auxiliary winding is configured such that the number of turns of the auxiliary winding, through which a current flows, varies according to the operating mode of the motor. When the motor starts, the number of turns of the auxiliary winding, through which a current flows, is reduced, thereby increasing the start efficiency of the motor. When the motor runs in normal mode, the number of turns of the auxiliary winding, through which a current flows, is increased, thereby increasing the operational efficiency of the motor.

Abstract: A position controller of a motor in which the position time can be shortened even if an external force is applied. A speed control unit (13) comprises a compensation low-pass filter (133) having a transfer function corresponding to a delay of a speed control system. The speed control unit (13) further comprises an integral control system including a speed integrator (132) for integrating the difference between a speed and a delay speed command to the low-pass filter (133) compensating the delay in the speed control unit. A proportional control system outputting a command proportional to the speed command, and a multiplying means (134) for multiplying the sum of outputs from the integral control system and the proportional control system by a speed proportional gain and outputting the result as a torque command.

Abstract: The invention is directed to controlling an electric motor by means of a frequency converter. The frequency converter can be connected to one of several different mains voltages. According to the present invention, the maximum output power of the frequency converter, is limited when the actual mains voltage is lower than the maximum nominal mains voltage, for which the frequency converter is designed, and during the limitation the frequency converter controls the speed of the motor within a power range up to a limited maximum output power. This gives a genuine multi-voltage unit, which can be connected to a wide range of mains voltages.

Abstract: A method for controlling a device including a plurality of switching devices operated in accordance with a pulse width modulation technique includes receiving a reference voltage signal associated with a first pair of the switching devices. A switching signal is generated. The first pair of switching devices are controlled based on the reference voltage signal and the switching signal in accordance with the pulse width modulation technique. A frequency of the switching signal is varied based on the value of the reference voltage signal.

Abstract: The present invention can diagnose a potential discrepancy in electrical operating characteristics of a three phase electric motor by generating two independent torque estimates using a plurality of current sensors and a shaft position sensor. The invention provides a strategy to generate two independent torque estimates of a three phase electric motor comprising first and second systems to determine currents in two motor phases, first and second systems to generate a first and second estimate of motor shaft position, and first and second systems to generate first and second estimates of motor torque using the first and second systems to determine current in each motor phase and the first and second values of motor shaft position. The present invention detects also an electrical operating characteristic discrepancy in an electric motor-propelled vehicle's electrical components and subsystems, including single subsystem discrepancies between the two independent torque estimates.

Abstract: A motor variator and a driving method thereof are provided for controlling the operating speed of a fan, which employ an alternate current chopper to change the working cycle and the rotary speed of a stepless motor. The motor variator includes a high-frequency alternate current chopper connected to an induction coil of an induction motor, an alternate current power supply connected to the high-frequency alternate current chopper and a controller connected to the high-frequency alternate current chopper for outputting a switch signal to the high-frequency alternate current chopper, such that the high-frequency alternate current chopper is controlled by the switch signal to perform a chopper action for the alternate current power supply and output a drive voltage, so as to change the rotary speed of the induction motor.

Abstract: An automotive generator/motor is driven by a battery via an inverter. Resistance 2Ra0 is expressed by 2Ra0=Vmax/?{square root over (3)} Iamax, where Vmax is a maximum voltage applicable across any two terminals from the inverter and Iamax is a maximum current which must be fed from the inverter into each of the terminals when the maximum voltage Vmax is applied for maximizing torque produced by the automotive generator/motor at a power factor of 1 under voltage saturation conditions, and the armature winding is configured such that resistance 2Ra across any two terminals satisfies a relationship expressed by 0.8Ra0?2Ra?3.8Ra0.

Abstract: Systems and methods are provided for dynamically changing configurations of multi-inverter drive systems. By changing configurations during operation, a multi-inverter system of the present invention can provide greater than half of full output power during failure of a power cell and can provide efficient braking torque during regeneration. The inverter drive system includes a plurality of single pole inverter cells and a configuration switch system connecting the single pole inverter cells in a star configuration and for changing the connection configuration of the single pole inverter cells. In one embodiment, the configuration switch system is adapted to dynamically change the star configuration of the inverter system to a mesh configuration during operation of the load. In another embodiment, the configuration switch system is adapted to dynamically change the star configuration of the single pole inverter cells to form a polyphase inverter.

Abstract: A method of controlling of an induction machine using an inverter is disclosed with output LC filter. The method includes determining an inverter output current vector (iA), determining an inverter output voltage vector (uA), and forming a full-order observer having a system matrix (Â) and gain vector (K). The observer produces an estimated rotor flux linkage vector ({circumflex over (?)}R), an estimated stator current vector (îs), an estimated stator voltage vector (ûs) and an estimated inverter output current vector (îA). An estimation error (iA?îA) of the inverter output current vector is determined, and a speed adaptation law is formed based on the estimation error of the inverter output current vector for determining an estimate for electrical angular speed ({circumflex over (?)}m) of the induction machine. The induction machine is controlled based on the produced estimates and a measured inverter output current.

Abstract: A method of providing ride-through capability in a chiller/refrigeration system employs a variable speed drive with an active converter stage, a DC link stage and an inverter stage for providing variable frequency and voltage to power at least one motor. An induction motor is coupled to the output of the inverter stage for driving a compressor in the chiller/refrigeration system. The ride-through method comprises operating the active converter to regulate the DC link voltage of the DC link stage to a predetermined voltage level until the current through the active converter equals a predetermined current limit, then transferring regulation of the DC link to the inverter upon reaching the current limit of the converter. The compressor is unloaded, and the power flow through the inverter is reversed to maintain the voltage level of the DC link stage.

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: A system and method for controlling an electric motor is disclosed. The method comprises determining the operating load of the electric motor and then calculating the voltage to be applied to the electric motor in response to the operating load. The voltage to be applied operates the motor in an efficient manner for the given load. The frequency of the voltage to be applied to the electric motor is calculated in response to the operating load such that the frequency of the voltage to be applied operates the motor in an efficient manner. Power is applied to the motor with the voltage and frequency calculated in order to operate the motor in an efficient manner for the given load.

Abstract: A control device of a motor used in, for example, electric power steering control of a vehicle has to monitor the operation thereof to execute such a processing as stopping the control without delay upon detection of error. However, conventional monitoring devices have a disadvantage of taking a long time period the detection or not being able to detect an error of no output. A three-phase inverter circuit 52 having a substantially constant operation period is employed. The inverter 52 outputs an output waveform also at the moment of not driving the motor 2. An inverter period monitoring circuit 555 is provided to monitor a period of the output waveform. When the period comes to be too large or too small as compared with a carrier period of the inverter, an alarm is outputted, and control of the inverter is stopped.

Abstract: An apparatus for anti-islanding protection of a distributed generation with respect to a feeder connected to an electrical grid is disclosed. The apparatus includes a sensor adapted to generate a voltage signal representative of an output voltage and/or a current signal representative of an output current at the distributed generation, and a controller responsive to the signals from the sensor. The controller is productive of a control signal directed to the distributed generation to drive an operating characteristic of the distributed generation out of a nominal range in response to the electrical grid being disconnected from the feeder.

Abstract: A driving apparatus of a three-phase induction motor includes: a three-phase power supply unit for supplying three-phase power; a rectifier for rectifying the three phase voltage supplied from the three phase power supply unit; a voltage reducing unit for reducing a DC voltage generated from the rectifier and outputting a stabilized DC voltage; and an inverter unit for varying the DC voltage outputted from the voltage reducing unit to a three-phase AC voltage and driving a three-phase induction motor. A power-factor degradation generated during supplying a DC voltage to the inverter to drive the three-phase induction motor is prevented, a harmonic wave is removed, and because a high-priced inverter component is not necessary, its relevant expense is reduced.

Abstract: A system and method for controlling operation of a component include using at least two sensors arranged to sense an operating condition of the component. The system further includes a controller that controls the component in response to feedback signals output by one or more of the sensors. The controller also determines how the sensor feedback signals are to be used in controlling the component. To this end, the controller includes a model-based statistical filter for each one of the second sensors.

Abstract: Systems and methods for controlling and/or calculating the torque for a field oriented induction motor operating at a given stator frequency. The systems and methods include calculating the torque using a first algorithm when the motor is at or below a first predetermined stator frequency, a second algorithm when the motor is at or above a second predetermined stator frequency, and a third algorithm when the motor is between the first predetermined stator frequency and the second predetermined stator frequency.

Abstract: A simple and economical mechanism providing automatic motor control. The mechanism includes a motor-rated relay directly connected to line voltage and the input terminal of a motor winding, and receiving a signal from a sensing device connected to line voltage and to a signal input on the relay. The relay and sensing device may be housed within a waterproof enclosure, or may be separately housed within a connection enclosure and a separate sensing device enclosure remote from the connection enclosure, the two enclosures being connected by a cable. The sensing device triggers the relay to control the supply of current to the motor winding.

Abstract: Processor-based field oriented control for brushless doubly-fed induction machine having first and second polyphase stator windings is programmed to operate the machine in various modes, as a motor or a generator, with bumpless switching between operating modes. An electronic power converter controls a current supplied to the first stator winding to control the torque of the machine, with the second stator winding selectively connected to an AC line. Stationary coordinates for in-phase and quadrature current commands are coordinate transformed using a voltage vector for voltage induced on the first polyphase stator winding to control current in the first stator winding, with or without a position sensor. The electronic power converter controls the voltage supplied to the first stator for generating, with the second stator selectively connected to a load. The machine can also be controlled to operate as a singly-fed motor at lower speeds, with the second stator winding shorted.

Abstract: An alternating current (AC) electrical motor/generator electrodynamic machine and methods include, according to disclosed embodiments of the invention, providing a wound rotor having a polyphase AC winding and a damper winding. The machine can operate as a low slip induction motor or generator, and alternatively can operate as a synchronous motor or generator.