Abstract: A controller outputting a voltage instruction for drive control to a electric rotating machine includes a drive voltage instruction calculation section calculating drive voltage instructions for driving the electric rotating machine, a position estimation voltage generator generating position estimation voltage instructions for position estimation about the electric rotating machine, a noise reduction voltage generator generating noise reduction voltage instructions for reducing noise occurring from the electric rotating machine along with input of the position estimation voltage instructions to the electric rotating machine, and adders outputting, to a voltage application means, a voltage instruction obtained by adding the position estimation voltage instructions and the noise reduction voltage instructions to the drive voltage instructions.

Abstract: A control device of a synchronous machine is disclosed. The control device includes an inverter configured to provide an output current to a synchronous machine. A controller configured to control the output current and to estimate a voltage command, at least in part, by using pulse width modulation to choose a non-zero vector at a time when the inverter is not driving the synchronous machine with the output current. The estimating the voltage command is performed without using a zero vector. A phase angle and angular velocity estimating section configured to estimate a phase angle and an angular velocity of a rotor of the synchronous machine based, at least in part, on an inductance value, an induction voltage value, the voltage command, and the output current. The controller is further configured to control the output current based, at least in part, on the phase angle and the angular velocity.

Abstract: A motor drive apparatus receiving power from a power source and driving a motor with independent polyphase systems of excitation coils, comprises: a control circuit and power converters each corresponding to one system, each including an inverter circuit, an interrupter circuit, and a temperature detector, the inverter circuits being connected in series to the power source and, while not short-circuited, supplying power to the excitation coil, wherein the control circuit detects an operating state of the motor, short-circuits the inverter circuits and interrupts the interrupter circuits for a subset of power converters defined according to the operating state, such that a source voltage is supplied to non-short-circuited inverter circuits, and, when a power converter exceeds a predetermined temperature, the control circuit short-circuits the inverter circuit and interrupts the interrupter circuit thereof, and, in another power converter not exceeding the predetermined temperature, operates the inverter circui

Abstract: There is provided a single-phase AC synchronized motor that does not need smooth of rectifier waves but stably performs shift from a starting operation to a synchronized operation. In the motor, based on detected signals of a position sensor, rectified current is reciprocally flowed to each direction of a single-phase coil which starts the motor. The motor includes a start-up operation circuit with a sensor starting period that increases a rotational speed until reaching to a first predetermined rotational speed; and a control device that controls operation of the motor as that shift to synchronized operation is performed when a rotational speed of a permanent magnetic rotor is reached to a second predetermined rotational speed nearby a synchronized rotational speed but not exceeding the synchronized rotational speed, and when the rise and fall of detected signals of the position sensor and the zero-cross point of AC current are approximately correspondent to each other.

Abstract: The present invention provides a simple, robust, and universal position observer for use with sensorless synchronous machines. The observer may be implemented using an equivalent EMF model of a synchronous machine or, alternately, using a sliding mode controller based on the equivalent EMF model of the synchronous machine. The observer may be used on any type of synchronous machine, including salient or non-salient pole machines such as a permanent magnet, interior permanent magnet, wound rotor, or reluctance synchronous machine. The observer provides low sensitivity to parameter variations and disturbances or transient conditions in the machine. In addition, no knowledge of speed is required as an input to the observer and an estimated position may be calculated using a subset of the machine parameters.

Abstract: A brushless motor controller is disclosed. The brushless motor controller includes a control unit and a drive timing generation unit. The control unit detects a load state of the motor. The drive timing generation unit generates a normal energizing timing determined by the rotational position of the rotor. Also, the drive timing generation unit generates an advancing angle energizing timing determined by the rotational position of the rotor and advanced by a predetermined amount from the normal energizing timing, generates a delay amount that changes in correspondence with the detected load state of the motor and the rotational speed of the rotor, and generates a final advancing angle energizing timing delayed by the delay amount from the advancing angle energizing timing.

Abstract: A two-phase BLDC motor comprises a stator and a rotor. The stator has a stator core and a two-phase winding wound on the stator core. The stator core comprises a plurality of teeth with slots formed between adjacent teeth. The rotor rotor has a plurality of magnetic poles formed by at least one permanent magnet. The windings are received in corresponding slots in such a way that each winding spans multiple teeth and the direction of current flowing through the windings in any one slot at any one time is the same.

Abstract: A motor magnetic pole position correction method includes preventing a movement of a movable element of a direct drive motor by mechanical brake (step S9), generating a command that designates a position spaced or separated from the present position (step S10), detecting a torque command value of the direct drive motor (step S12), determining a magnetic pole position correction value based on a comparison between the detected torque command value and a predetermined threshold value (steps S14 and S16), storing the determined magnetic pole position correction value in a memory (step S18), and performing motor control using an electrical angle offset value obtained based on the magnetic pole position correction value stored in the memory.

Abstract: A power supply device for a variable rotation speed drive includes a free-running converter connected to a land-based power grid, and an inverter connected to the variable rotation speed drive. A direct-current cable electrically connects the DC side of the converter with the DC side of the inverter. The inverter includes a plurality of phase modules having an upper and a lower valve branches with least two series-connected, two-pole subsystems with distributed energy storage devices. The inverter is located on the seabed in immediate vicinity of the variable rotation speed drive. Signal electronics of the inverter is located on land. In this way, the distance between the power supply on land and the drive on the ocean floor can reach several hundred kilometers, with ocean depths of several kilometers.

Abstract: An electric drive (1) comprises: a permanent magnet brushless motor (2), a motor (2) power supply bridge (3), a circuit for controlling the power supply bridge (3) according to rotor position and phase currents (IS); the drive (1) comprises a circuit (6) for detecting the zero crossings of the induced counter electromotive force (ES) in the stator windings to determine the position of the rotor and a circuit (25) for indirectly detecting the amplitudes of the phase currents (IS).

Abstract: Disclosed herein is a sensorless-type brushless DC motor, including: a magnet provided in a rotor; and a stator formed by winding a coil on a core stacked with sheets while facing the magnet, wherein the position of the rotor is detected by detecting back electromotive force induced to the coil, the back electromotive force includes a harmonic component 5 times higher than a fundamental wave, and an amplitude ratio of the 5-times harmonic wave to the fundamental wave is set to be 1% or more. Further, the sensorless-type brushless DC motor can prevent a failure in detecting an initial position of the rotor by controlling a waveform of the back electromotive force and minimize an increase of a starting time.

Abstract: An electric drive unit for a water-bearing domestic appliance having a converter to provide a supply voltage from a multiphase voltage system; a control device to control the converter in order to operate a first electric motor connected to the multiphase voltage system; a load-current-carrying DC link arranged upstream of the converter; and an electrical device connected to at least part of the multiphase voltage system or the load-current-carrying DC link via a connection device, wherein the electrical device has a second electric to operate a hydraulic pump and/or a blower and/or a valve.

Abstract: In response to the determination or estimation of a back EMF zero crossing event for the phase, a time T1 is calculated, T1 being representative of the desired absolute maximum value of the phase current. Current samples are taken by the current sampling unit symmetrically centered around T1. The values of the samples CS[1] to CS[10] are then input into the error function to calculate an error function value. The calculated error function value is input to the lead angle control unit which calculates a value for lead_angle. The value of lead_angle is calculated to be the adjustment in phase angle of the driving voltage profile that will minimize the absolute value of the error function. In generating and adjusting the driving voltage profile the driving voltage generation unit takes into account both lead_angle and the output of the position and speed estimation unit.

Abstract: A coil current detector detects a current component flowing through a coil. A scaling unit scales a drive signal. An induced voltage component extraction unit extracts an induced voltage component by removing the drive signal, scaled by the scaling unit, from the coil current component detected by the current detector. A phase difference detector detects a phase difference between the phase of the drive signal and that of the induced voltage component. A signal adjustment unit adjusts the drive signal so that the phase difference detected by the phase difference detector can be brought close to a target phase difference.

Abstract: An apparatus for controlling operation of inverter system configured to drive a motor by using an inverter, and to normally operate the motor in a resonance-generated frequency band if the resonance occurs, and a method thereof are disclosed, wherein the method includes detecting a current outputted by an inverter system to a motor, if an operation frequency of the motor is in a resonance frequency band, converting the detected current to a d axis current and a q axis current, calculating a difference between the converted d axis current and pre-sampled d axis current (magnetic flux portion), multiplying the calculated difference by a preset comparative control gain to calculate a comparative control voltage, and adding the calculated comparative control voltage to a torque portion voltage responsive to an operation frequency of the motor to generate a driving voltage of the motor.

Abstract: A space vector based synchronous modulating method includes sampling a frequency f of a reference voltage vector; checking a relational table of frequencies and carrier wave ratios by the frequency f so as to obtain a carrier wave ratio N; obtaining a passing angle ?? of the reference voltage vector by ??=2?/N; obtaining a modulating angle ?m of the reference voltage vector by ?m=(Nth?1)×??, in which Nth indicates which time of sampling; obtaining a modulating ratio m according to a modulating ratio-frequency curve; accounting and synthesizing an output angle of three basic voltage vectors of the reference voltage vector according to the modulating angle ?m and the passing angle ?? of the reference voltage vector and the modulating ratio m; comparing a variable quantity ?f the reference voltage vector angle ? and the output angle of three basic voltage vectors, and outputting corresponding basic voltage vectors according to the comparing result; synthesizing an output voltage in accordance with the reference

Abstract: A brushless, synchronous machine is provided. A brushless, synchronous motor includes a rotor, a stator extending around at least a portion of the rotor and separated from the rotor by an air gap, a first stator winding, a second stator winding, a third stator winding, a drive circuit, a first rotor winding, a second rotor winding, and a diode bridge. The first stator winding, the second stator winding, and the third stator winding are mounted to the stator to generate square waves. The drive circuit is configured to provide a current to the first stator winding, the second stator winding, and the third stator winding, wherein the current includes an alternating current (AC) component and a direct current (DC) component. The first rotor winding is mounted to the rotor to form a plurality of third harmonic coils. The second rotor winding is mounted to the rotor.

Abstract: An electric system that includes a single-phase permanent-magnet electric machine and a control system for driving the electric machine under load at speeds in excess of 60 krpm. Additionally, a product that includes the electric system.

Abstract: To develop a motor which can directly drive a brushless motor using a conventional circuit for an inverter without smoothing circuit and a circuit for a matrix converter that are for a brushed motor that operates on single-phase 100 V. Magnetic cores are attached to a motor shaft to increase inertial force. A magnetic-drive-pulsation motor which modulates torque is realized using force of attraction and repulsion generated by outer magnets and magnetic cores. The magnetic-drive-pulsation motor can be driven using the inverter and the matrix converter on single-phase 100 V power supply.

Abstract: A rotating electrical machine including a first member (10) capable of generating a magnetic field which rotates relative to the first member, and a second member (6) which is provided with a winding through which a current can flow, such that the rotating magnetic field drives the second member in rotation. An electrical value which is at least related to the current is measured (18) and the generation of the rotating magnetic field is started (12) at a time which is determined as a function of the electrical value which is measured. A method of controlling the machine is also disclosed.

Abstract: A failure identification part identifies a switching element pair having off-failure, in which a FET of the switching element pair in a first inverter part is disabled to turn on. A failure-time control part controls other switching element pairs and of the first inverter part based on failure-time phase current command values calculated as a function of a rotation position and a q-axis current command value. The failure-time control part controls a second inverter part normally. A motor is persistently driven with the minimum reduction in motor torque, even when the FET fails.

Abstract: The invention relates to converters (inverters, pulse or frequency converters) and to driving “magnetically active” operating means. According to one embodiment, a circuit arrangement for feeding the operating means in at least one first winding phase (S1), comprises a first branch (Z1) of a frequency converter (WR1) adapted for and operable at a switching frequency of not higher than 5 kHz for outputting a main alternating current generated at said switching frequency and having a substantially lower operating frequency (f1) to a winding (L1). A second branch (z1) of another frequency converter (WR2) is adapted for and operable at a second switching frequency of more than 5 kHz for outputting a supplementary alternating current generated at said switching frequency to the same winding (L1). In the at least one winding (L1), the two alternating currents (iA(t); iB(t)) of the two branches (Z1, z1) are superimposed to form a sum current.

Abstract: A method of operating a synchronous motor having a stator that includes a set of electromagnets and a permanent magnet rotor. The synchronous motor is controlled by calculating in a flux controller a measure of a flux magnitude, which is the magnitude of the stator flux of the motor and by calculating in a load angle controller a measure of a load angle. Information about a desired motor torque or a reduced motor torque, which is smaller than the desired motor torque, is input to the load angle controller and the load angle controller calculates the measure of the load angle depending on the input motor torque. The measure of the flux magnitude is combined with the measure of the load angle to obtain commands for controlling electric currents of electromagnets of the stator, thereby directly controlling the stator flux.

Abstract: A motor drive controller includes a position detector that detects and outputs positional signals representing rotational positions of the magnetic rotor at first resolution, a position change detector that detects and outputs position change signals representing rotational positions of the magnetic rotor at second resolution higher than the first resolution, a phase synchronizing circuit that generates and outputs low resolution absolute phase information based on the positional and position change signals. The phase synchronizing circuit generates and outputs high-resolution absolute phase information based on the position change signals. A drive voltage signal outputting device outputs a drive voltage signal causing the current to flow through the coils in accordance with the absolute phase information.

Abstract: The present invention aims to provide a synchronous motor drive system that is capable of suppressing ripples in current while reducing switching loss. The system includes three-phase inverters 201-203, a control circuit 400 for controlling the operations of the three-phase inverters and a synchronous motor 300 including a plurality of three-phase coils. To control the operations of the three-phase inverters, the control circuit 400 causes the three-phase inverters 201 and 203 and the three-phase inverter 202 to use different carrier frequencies to generate three-phase AC power, and each of the three-phase inverters supplies a different one of the three-phase coils with three-phase AC power.

Abstract: A motor driving circuit is applied to a motor unit, a pushrod unit, and a load unit. The motor unit is driven by the motor driving circuit. The pushrod unit is driven by the motor unit to lengthen or shorten. The load unit is pushed by the pushrod unit. A relay unit of the motor driving circuit is provided to brake the motor unit, thus raising the self-locking force of the motor unit when the pushrod unit lengthens to the maximum length or shortens to the minimum length, or the power supply is cut off.

Abstract: An electronic control circuit for a brushless motor has an input power circuit providing a DC voltage and a microcontroller integrated circuit receiving the DC voltage. The microcontroller integrated circuit provides three-phase control signals according to a space vector control method. A microprocessor connected to the microcontroller integrated circuit executes supervisory control over the electronic control circuit. An inverter circuit receives the three-phase control signals from the microcontroller integrated circuit and provides driving signals to the brushless motor based on the three-phase control signals received from the microcontroller integrated circuit.

Abstract: A synchronous electrical machine having a plurality of phases, a detecting unit arranged to detect a fault in at least one of the phases of the synchronous electrical machine, an isolating unit arranged to isolate the at least one phase of the synchronous electrical machine with the fault, a phase shift unit arranged to produce a controlled phase shift between the voltage and the current within the remaining phases of the synchronous electrical machine to adjust the phase angle and magnitude of the second harmonic powers produced by the remaining phases of the synchronous electrical machine such that the vector sum of the second harmonic power vectors of the remaining phases of the synchronous electrical machine is zero.

Abstract: The present invention relates to synchronized vibration devices that can provide haptic feedback to a user. A wide variety of actuator types may be employed to provide synchronized vibration, including linear actuators, rotary actuators, rotating eccentric mass actuators, and rocking mass actuators. A controller may send signals to one or more driver circuits for directing operation of the actuators. The controller may provide direction and amplitude control, vibration control, and frequency control to direct the haptic experience. Parameters such as frequency, phase, amplitude, duration, and direction can be programmed or input as different patterns suitable for use in gaming, virtual reality and real-world situations.

Abstract: A motor having an alternating current electrical source, a light power circuitry, a stationary transcutaneous energy transmission coil spaced from a rotatable transcutaneous energy transmission coil, a plurality of phototransistor arrays positioned on a rotatable platform and each phototransistor array corresponds to and rotates in conjunction with an armature winding used in the motor. Each phototransistor array (i) receives an alternating current from the rotatable transcutaneous energy transmission coil, and (ii) charges (a) each armature winding to a constant high voltage when the motor is operating and (b) each phototransistor/MOSFET power source to a desired power level. When the light from the light power circuitry contacts a phototransmitter, the phototransistor array is turned on so the armature winding associated with that phototransmitter generates an instantaneous maximum magnetic field.

Abstract: When it is determined that a rotor is initially in a stationary state, a current vector is applied to a coil by a vector control method so as to rotate the rotor in a forward direction from a present position of the rotor regardless of a predetermined start position of the rotor. Therefore, a motor can be stably started with less power consumption and noise/vibration.

Abstract: A motor drive circuit is configured to drive a motor based on first and second position detection signals opposite in phase to each other, the signals having a frequency corresponding to a rotational speed of the motor and indicating a rotational position of the motor. The circuit includes a first level-shift circuit, a second level-shift circuit, a timing detecting circuit, and an output circuit. The first level-shift circuit is configured to shift a level of at least either one of the first and second position detection signals so that a first period, during which a first output signal corresponding to the first position detection signal is higher in level than a second output signal corresponding to the second position detection signal, becomes longer than a second period, during which the second output signal is higher in level than the first output signal.

Abstract: Drive voltages to a sensorless brushless DC motor are regulated by varying the width of a single drive pulse (PWM pulse) centered in each of the commutation periods. Switching losses are thereby cut to an absolute minimum because there are only two transitions (on and off) in each drive commutation period. Back EMF zero-cross detectors determine the electrical timing relationships during each electrical cycle. Since the PWM drive pulses are always centered in each of the commutation periods, there will always be back EMF available for measurement of “zero-crossings.” A digital device controls power switching transistors to produce one single PWM pulse during each of the commutation periods.

Abstract: A system and method are presented for aligning a rotor in a motor. The motor may include the rotor and a plurality of pairs of electromagnets. One or more pairs of electromagnets may be excited at a first excitation level. The one or more pairs of electromagnets may be less than all of the plurality of pairs of electromagnets. The excitation of the one or more pairs of electromagnets may be increased to a second excitation level over a first period of time. The excitation of the one or more pairs of electromagnets may be decreased to a third excitation level over a second period of time. Exciting the one or more pairs of electromagnets, increasing the excitation, and decreasing the excitation may cause the rotor to stop in a known position.

Abstract: Disclosed herein is a method of controlling the current of a high-speed Switched Reluctance Motor (SRM) using an inverter circuit including a first switching element, a second switching element, a first diode, a second diode and a reactor, wherein the first switching element and the first diode, the second diode and the second switching element are connected to a bridge circuit, and one end of the reactor is connected to the junction of the first switching element and the first diode, and the remaining end of the reactor is connected to the junction of the second diode and the second switching element; and excitation mode, free-wheeling mode-1, the excitation mode, and free-wheeling mode-2 are sequentially performed in a unit period T, and, when the control is terminated, demagnetization is performed.

Abstract: Methods and devices are presented herein for estimating induction motor inductance parameters based on instantaneous reactive power. The induction motor inductance parameters, e.g., the stator inductance and the total leakage factor, can be estimated from motor nameplate data and instantaneous reactive power without involving speed sensors or electronic injection circuits.

Abstract: A method for operating a synchronous motor wherein a magnetic field is generated by a first motor component in a predetermined orientation, the method including generating a relative movement between the first and a second motor component limited to a predetermined value, and determining a direction of the relative movement, wherein the generating and determining are repeated until a change in the direction of the relative movement occurs, wherein a magnetic field having a changed orientation with regard to a previously generated magnetic field is generated by the first motor component, and wherein the orientation of the magnetic field with the changed orientation is changed by a predetermined orientation section and depending on the determined direction of the relative movement. The invention encompasses an amplifier for operating a synchronous motor and a system including an amplifier and a synchronous motor.

Abstract: The present disclosure includes electrical motor/generator drive systems and methods that significantly reduce inverter direct-current (DC) bus ripple currents and thus the volume and cost of a capacitor. The drive methodology is based on a segmented drive system that does not add switches or passive components but involves reconfiguring inverter switches and motor stator winding connections in a way that allows the formation of multiple, independent drive units and the use of simple alternated switching and optimized Pulse Width Modulation (PWM) schemes to eliminate or significantly reduce the capacitor ripple current.

Abstract: The present invention provides a position sensorless control method of a high performance permanent magnet synchronous motor during emergency operation, which can accurately detect a magnetic pole position of the synchronous motor based on a position sensorless vector control using an adaptive observer configured based on a permanent magnet synchronous motor model.

Abstract: A control method for a brushless, three-phase DC motor. A voltage induced by rotation of a rotor may be sampled at a first expected zero crossing value to produce a first sampled voltage value. An average of a plurality of sampled voltage values, including voltage values sampled at a plurality of prior expected zero crossing values and the first sampled voltage value, may be calculated. The first sampled voltage value may be subtracted from the calculated average to produce a delta zero crossing error. A pulse-width modulation duty cycle may be adjusted based on the delta zero crossing error. The pulse-width modulation duty cycle may be used to control a rotational velocity of the rotor.

Abstract: When an output pattern (LLL or HHH) due to a signal with a prescribed logic level corresponding to a ground short or instantaneous interruption of an output signal line of Hall ICs 17 is supplied via the output signal lines, and if output patterns based on detection signals supplied before and after the output pattern are found to be different by comparing them, a decision is made that there is a possibility that a shift of a rotor 11 from a target position and counterrotation of the rotor 11 involved with it can occur.

Abstract: A method of operating a WFSM in a motoring mode determines a relative position of a PMG rotor with respect to the WFSM rotor. A PMG is coupled to the WFSM via a coupling shaft. A relative difference between the WFSM rotor position and the PMG rotor position is determined based on carrier injection sensorless (“CIS”) stimulation signals. The relative difference between the PMG rotor and the WFSM main machine in conjunction with the PMG rotor position is used to determine the WFSM rotor position during motoring operation of the main machine. A stator of the WFSM main machine is energized to maintain operation of the WFSM in response to the detected main rotor position.

Abstract: Method for control of synchronous electrical motors that enables determining the instantaneous motor load angle and rotor speed without using rotor position sensors. The method is realized with solving the set of differential equations that govern the currents in the stator windings of the motor for the time intervals between each two consecutive crossings of the currents in the windings of their set values and deriving relationships between the induced in the windings back-electromotive force voltages and the parameters of the Pulse Width Modulation. The parameters of the Pulse Width Modulation are measured and stored in a memory and based on the derived relationships the values of the back-electromotive force voltages are calculated continuously in time. From the values of the back-electromotive force voltages the motor load angle and rotor speed are calculated and used as feedback signals for the closed-loop control of the motor.

Abstract: There is provided a motor. The motor may include a rotor case including a driving magnet formed on an inner circumferential surface thereof and providing a driving force by interacting with a coil of a stator, a low-speed control magnet formed on an outer circumferential surface of the rotor case and generating a frequency allowing for low-speed rotation enabling label printing as the rotor case rotates at a low speed; and a sensing part sensing an analog signal generated from the low-speed control magnet.

Abstract: There is provided a control device of a permanent-magnet type synchronous motor that sets a synchronous operation current at start-up in response to a current limiting value determined from the temperature of an inverter that supplies three-phase power to the permanent-magnet type synchronous motor, that monitors an output voltage or an output current of the inverter during a rotation stabilizing period after start-up, and that updates the synchronous operation current using this output voltage or output current.

Abstract: A method of synchronizing the timing of a plurality of physically coupled print engines wherein the receiving sheet is inverted between a first and a second print engine including determining any change in the speed of the master print engine relative to the speed at original set up and adjusting the timing parameters within the slave print engines based on the speed of the master engine.

Abstract: An n-phase brushless motor device is provided. The device includes a magnet for magnetic pole position detection having a number of poles twice as many as that of a rotor and fixed to a face perpendicular to a rotation axis of the rotor; n main Hall elements arranged opposite to the magnet, for detecting a magnetic pole position of the rotor; n sub Hall elements arranged in such a way as to have an offset in a direction of a periphery with respect to the main Hall elements, for detecting the magnetic pole position; and a control unit for counting “2” according to a change in an output pattern of the main Hall elements, for counting “1” when the output pattern is the same as that of the sub Hall elements at a predetermined timing, and for controlling a rotation of the rotor according to these counted values.

Abstract: A control system for an electric machine, the control system including a position sensor and a drive controller. The drive controller generates one or more control signals for exciting a winding of the electric machine in response to edges of a signal output by the position sensor. The times at which the control signals are generated by the drive controller are corrected by a position-sensor offset that is fixed over an operating speed range of the electric machine.

Abstract: A rotary electric machine controller including a current detector detecting rotary electric machine currents generated in a rotary electric machine, a position estimation mechanism outputting an estimated position in accordance with the rotary electric machine currents; a controller outputting voltage commands in accordance with the estimated position; a pulse-width modulator outputting logic signals which are pulse-width modulated in accordance with the voltage commands and with a switching cycle used for pulse-width modulation control; and a voltage application mechanism applying AC voltages for driving the rotary electric machine in accordance with the logic signals. The voltage commands output by the controller are obtained by superimposing, on fundamental voltages for driving the rotary electric machine, position detection voltages which each have a cycle equal to m times of the switching cycle and which are different in phase among respective phases.

Abstract: A differential amplifier detects a coil current Is at the time of steady rotation of a synchronous motor. An application voltage S0 at this time is detected from an output of an ATT circuit and so on. With the use of the coil current Is which is detected, the application voltage S0 at that time, and a predetermined scaling factor As, an induced current Ib is obtained based on Ib=As·S0?Is. The application voltage to the motor is controlled based on the induced current Ib which is obtained.