Abstract: A conventional apparatus with the above operation, includes a torque ripple due to harmonic wave components included in the detected fundamental wave of current frequency of the detected apparatus for controlling rotation speed, switching dead time and the like and accordingly, harmonic wave components are included in the induced voltage. Therefore, a ripple is generated in an estimated-calculated rotation speed and accordingly, precise speed control was not possible. Also, it was difficult to handle the apparatus by using an encoder and hole-sensor of the rotor position detection unit.

Abstract: A Switched Reluctance Motor or SRM is controlled by detecting signals indicating the angular position of the rotor of the motor and energizing the motor depending on these signals. The periods of the abovementioned signals are discretized into a given number of time windows, defining a table with a plurality of positions each corresponding to one of said time windows. A respective power supply configuration of the motor is associated with each of said positions of the table. The positions in the table undergo cyclical scanning and the motor is energized with the power supply configuration associated with the position identified in each case during the scanning movement. The scanning movement is performed from a reference position identifying the energization advance of the motor and preferably determined using a logic of the fuzzy type based on the speed of rotation and the load of the said motor.

Abstract: The invention provides a method and apparatus for maintaining the force, or torque, delivered by a variable reluctance motor as the speed of the motor increases. The method comprises the steps of sensing the speed of the motor and varying the number of turns of the motor's phase coil based on the sensed speed. The apparatus includes a motor speed sensor for sensing the speed of the motor and an inductance switch for switching the number of turns of the phase coil from a first value to a second value based on the sensed speed. One embodiment of the invention includes an inductance compensation circuit to compensate for the change in load inductance when the number of turns of the phase coil is switched.

Abstract: A digital calculation apparatus 4 including a position-detection means 14 for detecting the magnetic pole position, based on the detected current difference values of the synchronous motor 1 in a two-phase short-circuit state, takes in current flowing in the synchronous motor by generating an interruption trigger signal in synchronization with the PWM signals for driving an inverter 3, and driving an A/D converter with the generated trigger signal.

Abstract: A method and apparatus for controlling a permanent magnet synchronous motor (8) coupled to a turbo engine such that transient current and steady state current are minimized. The method comprises the steps of, for a given DC bus voltage, determining an acceleration profile as a function of a voltage-offset value, a low-speed rated speed value, a high-speed rated speed value, a first desired speed for warming up the turbo engine, and a second desired speed where the turbo engine has sufficient torque to accelerate to its rated speed without the aid of the permanent magnet synchronous motor (8).

Abstract: A method for controlling a two-phase stepping motor gauge for an instrument cluster includes the steps of: providing a two-phase motor for displaying information to a driver, determining a desired position of the two phase motor at a rate and in a manner consistent with an intended application; updating a waveform to the input of a first inverter coupled to one of the motor coils; integrating the waveform using a first and second inverter to energize one of the motor coils. Thus, the present invention allows the control of a conventional two-phase motor coil using only one control signal. Additionally, the present invention requires low actual current to maintain gauge position.

Abstract: A controller for an electronically commutated electrical machine receives a feedback signal indicative of a parameter which it is desired to minimize, e.g. torque ripple, current, voltage, vibration or acoustic noise. The controller computes the amplitude and phase of a set of harmonics in the parameter and sequentially injects harmonics of the correct amplitude and phase to minimize the parameter. An optimizing routine iterates through the set of harmonics to further reduce the parameter.

Abstract: A switched reluctance drive is supplied from a power source and has a DC link, across which is a DC link capacitor. The phases of the machine are controlled by a controller which controls the switches connecting each phase winding to the DC link. The controller switches off the switches of each phase in a sequence which minimizes the peak voltage appearing on the DC link capacitor, thereby allowing a reduction in the voltage rating of the capacitor.

Abstract: A switched reluctance machine is supplied from two voltage sources during a cycle of excitation. The higher voltage is a conventional bus voltage obtained, e.g., from a low-voltage storage battery and an up-converter. The lower voltage is supplied directly from the battery. The higher voltage supplies the machine during only part of an excitation cycle, the lower voltage supply supplying the energy directly to the machine during the remainder of the excitation cycle. This reduces the duty of the up-converter and increases the efficiency of the overall drive. One method of operation of the circuit allows the elimination of the up-converter.

Abstract: A switched reluctance drive is supplied from a power source. The phases of the machine are controlled by a current chopping controller which uses an excitation strategy to minimize the supply current drawn for a particular output. The strategy is to allow an outgoing phase to freewheel as long as it produces positive torque while the incoming phase is excited.

Abstract: A controller for use in a switched reluctance (SR) motor drive is provided. The controller includes a DC-DC converter coupled to an inverter. The DC-DC converter can be a buck converter, a boost converter, or a buck-boost converter. The control parameters to the DC-DC converter can be optimal. In addition, the bus voltage of the motor drive can be reduced to a level such that the motor operates in single pulse mode. A capacitor can be connected in parallel across the outputs of the DC-DC converter supplying the inverter. Using the DC-DC converter to indirectly profile the phase current can reduce motor torque ripple.

Abstract: The invention relates to powering the electric drive motors (8) of a group of at least two machines (2, 3, 4), said motors operating in periodic motions, said periodic motions being mutually coordinated in a manner so as to control a parameter which is representative of the operations of the machines.

Abstract: A method for controlling driving of a Switched Reluctance Motor (SRM) is capable of operating the SRM normally according to a phase under the normal state in case a noise is inputted to a position sensor in the SRM. In order to achieve the advantage, the method for controlling driving of a three phase SRM using a position sensor having a rate of a rotor and a stator is {fraction (6/4)} or {fraction (12/8)} includes the steps of generating a sensor signal according to the position of a rotor in the SRM and operating the SRM by turning on respective phases in the SRM at the point of detecting a rising edge of the sensor signal and turning off the phase at the point of detecting a falling edge of the next sensor signal.

Abstract: An electrical machine is coupled to a load which has a torque profile which varies with angle. The machine is coupled so that the torque ripple of the machine is synchronized with the torque ripple of the load in such a manner as to provide an efficient drive system which can start at any angular position. This allows the size of the electrical machine to be reduced to a point where its average torque may be below the peak requirement of the load.

Abstract: When the brushless motor 1 at rest is started, phase excitation is performed twice such that different phases are excited. A commutation reference point is set at a position at which a rotor has stopped after the second-time excitation. A position detector outputs pulse signals in response to a movement of an object driven by the brushless motor 1. The pulse signals output from the position detector are monitored and commutation is controlled on the basis of the number of pulse edges of the pulse signals as counted starting from the commutation reference point. For example, the number of pulse edges output during a period starting from the commutation reference point and ending at a point of time at which commutation should be performed is measured in advance. When the number of pulse edges with reference to the commutation reference point becomes equal to the above predetermined number, it is determined that commutation timing has reached, and commutation is performed.

Abstract: A self-excited reluctance motor capable of driving a motor with a commutator and without having to use a commutator logic for power electric circuit. The self-excited reluctance motor includes a stator having a plurality of stator poles respectively wound by wires of different phases; a rotator having a plurality of rotator poles formed on an outer circumference thereof, the rotator rotatably inserted in the stator; and a commutator.

Abstract: A method to operate an electronically commutated DC motor driving a centrifugal pump and comprising a stator fitted with at least one winding and a rotor fitted with permanent magnets, said method including a monitored stepping operation within which one full revolution of the rotor is constituted by a sequence of distinct individual steps, the rotor being accelerated by applying a stator field and being decelerated to a stop before the stator field is commutated.

Abstract: A system and method for controlling a switched-reluctance motor, in which a control variable is selected for controlling a figure of merit of the motor. The motor is then operated at a first value of the control variable. The control variable is adjusted to a second value, and the motor is operated at the second value of the control variable. A first indicator indicative of the figure of merit of the motor operating at the first value of the control variable is compared to a second indicator indicative of the figure of merit of the motor operating at the second value of the control variable. Thereafter, a new value is selected as the first value of the control variable in response to the comparison of the first indicator first to the second indicator.

Abstract: An inverter for use in a switched reluctance (SR) motor drive is provided. The inverter comprises a first and second transistor for selectively providing current to an SR motor winding. A resonant-type snubber circuit is connected to the transistors to reduce turn-off loss. The snubber circuit includes a pair of diodes, a capacitor, and an inductor. The snubber circuit is reset during switch-on time of the transistors. At transistor turn-off time, the snubber circuit uses the capacitor to effectively limit the rate of change of voltage across the transistors. This allows the transistors to turn off with lower losses, and can also reduce the acoustical noise generated by the motor drive.

Abstract: An SR motor includes a stator having a plurality of salient poles and a rotor having another plurality of salient poles. Windings are wound around the plurality of salient poles and magnetic fields are generated in the plurality of salient poles. The number of salient poles of the rotor is determined depending upon a number of the salient poles of the stator. A supply mode for supplying power from a power supply to the windings, a reflux mode for setting both terminals of the windings to an identical potential, and a regenerative mode for recovering an electromotive force generated in the windings into the power supply are executed as the rotor rotates. The reflux mode and the regenerative mode are preferably repeated in a period during which the inductance of the windings is reduced as the rotor rotates.

Abstract: A driving control device of a motor includes a phase current control device for controlling a phase current which is fed to a phase coil of each phases of a motor in a predetermined control period of each phase coils so as to become a predetermined target current, respectively, a convergent control device for converging the phase current after the end of the control period of each phase coils and a driving signal generating device for generating a driving signal which controls the end timing of the phase current convergent control by the convergent control device so that the phase current convergent control is ended between a timing at which a reverse torque is generated by the phase current and the end timing of the control period for next phase coil.

Abstract: System and method for controlling the output torque of an electrical machine include a torque controller operable for receiving a motor input command, representative of a desired output torque, and generating a drive command to direct a motor to produce a predetermined output torque based on the motor input command. Further, the torque controller may include a sensor system for generating a feedback signal representative of an actual output torque of the motor. Additionally, the torque controller includes an input modulator and a speed modulator for adjusting the drive command based on the feedback signal and based on the motor input command to control a value of the predetermined output torque and to control a rate at which the predetermined output torque reaches the desired output torque.

Abstract: An energization control device is provided to prevent rapid decrease of current which is flowing through each of phase coils of an electric motor. A time duration is divided into three stages which ranges from an initiation of the current supply to the phase coil to a termination of the current supply to the phase coil. At the first stage, the second stage, and the third stage, soft/hard chopping energization control, 0-volt energization, and duty chopping energization control, respectively, are made. Energizing the phase coil is made by way of a first switching element and a second switching element. At the first stage, depending on an actual current value being in excess of a target current value, either of or both of the first switching element and the second element are made OFF. At the second stage, while the second switching element is being made OFF, the second switching element is made ON.

Abstract: A sensorless switched reluctance machine includes a stator with a plurality of circumferentially-spaced stator segment assemblies that include salient stator poles and inter-polar stator slots. Each of the stator segment assemblies includes a stack of stator plates forming a stator segment core, an end cap assembly, and winding wire wound around the stator segment core and the end cap assembly. The rotor defines a plurality of rotor poles. The rotor tends to rotate relative to the stator to a rotational position that maximizes the inductance of an energized winding. A sensorless drive circuit derives rotor position and energizes the winding wire around the stator segment assemblies based on the derived rotor position. Each stator plate includes a first radially outer rim section and a tooth section that extends radially inwardly from a first center portion of the first radially outer rim section.

Abstract: A synchronous motor control system includes a synchronous motor 1, an inverter 3 and a controller 4 wherein a current differential detecting unit 13 detects a variation of a motor current when the three phases of the motor 1 is short circuited by the inverter 3, namely at the moment when a carrier wave in a PWM signal generator 9 assumes maximum or minimum value, in a calculating unit 14 a phase &ggr; from &agr; axis of a stationary coordinate system to a three phase short circuited current differential vector is calculated, a phase &dgr; is estimated from d axis to the three phase short circuited current differential vector by making use of d axis current id and q axis current iq on d-q axes coordinate system in the controller 4, thereafter the magnetic pole position &thgr; with respect to &agr; axis is calculated from the phases &ggr; and &dgr;, based on thus calculated magnetic pole position &thgr;, d-q axes control units 11, 7 and 8 are constituted to control the synchronous motor, thereby a highly reliab

Abstract: Method and system for estimating rotor position of a switched reluctance machine is provided. The method allows for estimating flux linkage across a respective phase of the machine. The method allows for measuring of magnetization curves at aligned and unaligned positions of the machine. The method further allows for computing magnetization reference data between the aligned and unaligned positions. A storing step allows for storing rotor position data based on the magnetization reference data. The stored rotor position data is indicative of rotor position variation as a function of phase current. A relating step allows to relate the estimated flux linkage to the magnetization reference data to determine, for a respective phase current, correspondence of the estimated flux linkage relative to the magnetization reference data. A retrieving step allows for retrieving stored rotor position data when said correspondence is determined.

Abstract: Method and system for estimating rotor position of a switched reluctance machine is provided. The method allows for estimating flux linkage across a respective phase of the machine. The method allows for measuring of magnetization curves at aligned and unaligned positions of the machine. The method further allows for computing magnetization reference data between the aligned and unaligned positions. A storing step allows for storing rotor position data based on the magnetization reference data. The stored rotor position data is indicative of rotor position variation as a function of phase current. A relating step allows to relate the estimated flux linkage to the magnetization reference data to determine, for a respective phase current, correspondence of the estimated flux linkage relative to the magnetization reference data. A retrieving step allows for retrieving stored rotor position data when said correspondence is determined.

Abstract: A switched reluctance machine includes a stator with a plurality of circumferentially-spaced stator segment assemblies that include salient stator poles and inter-polar stator slots. Each of the stator segment assemblies includes a stack of stator plates forming a stator segment core, an end cap assembly, and winding wire wound around the stator segment core and the end cap assembly. The rotor defines a plurality of rotor poles. The rotor tends to rotate relative to the stator to maximize the inductance of an energized winding. A drive circuit energizes the winding wire around the stator segment assemblies based on a rotational position of the rotor. Each stator plate includes a first radially outer rim section and a tooth section that extends radially inwardly from a first center portion of the first radially outer rim section.

Abstract: A switched reluctance drive is supplied from a voltage source which varies from the voltage at which the control laws for the drive were determined. The control system compensates for this by modifying both the speed and torque values used to determine the correct firing angles for the demanded load. The system works over a very wide range of voltage variation and is independent of the shape of the torque/speed curve of the drive.

Abstract: A method to control a switched reluctance motor (SRM) with a first phase (1) and a second phase (2) comprises: aligning the rotor with the second phase (2); at a first time point (t1), energizing the first phase (1) with a phase voltage that is substantially constant; monitoring an increase of the phase current (I1) in the first phase (1) until the phase current reaches a maximum (302); monitoring a decrease (303) of the first current (I1) until at a second time point (t2) the phase current (I1) reaches a minimum (304) and starts to increase again (305); de-energizing the first phase (1) at a third time point (t3) that follows the second time point at (t2) at a predetermined time interval; and repeating energizing, monitoring and de-energizing for the second phase (2) instead of the first phase (1).

Abstract: Described is a method of optimizing performance parameters of a switched reluctance motor comprising ascertaining the parameters of at least three objectives of the motor selected from the group consisting of firing angles, power on the shaft of the motor, drive efficiency, torque ripple coefficient, output torque, torque per rms current per cycle, torque per mean ampere, energy consumption, phase target current level, hysteresis band size, duty cycle, DC voltage and zero-volt control loop;

Abstract: A switched reluctance machine uses a Hall-effect device to detect the flux in the flux path for each machine phase. The flux signal from the Hall-effect device is fed back to a controller which compares the flux feedback with a demand signal to produce an error signal. The error signal is used to control the machine flux using a control law function actuating timed switches for each phase.

Abstract: A method for reducing a torque ripple of a Switched Reluctance Motor for detecting a position of the rotor using a position detection sensor, designing a pulse width if a position detection signal as an optimum one and decreasing a torque ripple of the motor by adjusting a duty rate of the pulse width modulation signal comprises the steps of setting a pulse width of a position detection signal in accordance with a position detection result of a motor rotor, outputting a signal for controlling of each phase in synchronization with a rising and falling edge of the position detection signal, and varying and outputting a duty rate of a pulse width modulation signal from the moment that a falling edge of the position detection signal is detected thus to have advantage of decreasing more than fifty percents of the torque ripple.

Abstract: The present invention is a motor control device for controlling current command values in relation to a permanent magnet reluctance motor which generates torque corresponding to the combined value of the torque resulting from the permanent magnet and the reluctance torque through field-weakening control in such a manner that the motor terminal voltage does not exceed the maximum inverter output voltage. In particular it controls the angle of the current relative to the motor rotor which is required for the purpose of field-weakening control, and ensures that this is stable and effective whatever torque is output.

Abstract: A switched reluctance machine is controlled without using a physical rotor position detector. The rotor position at start-up is determined by simultaneously injecting a current of known magnitude into two phases. The rise times of the currents are measured and used to interrogate a stored table of rise time against rotor angle for the known current level. This produces two possible rotor positions from each rise time. Comparisons of the pairs of angles yield the actual position.

Abstract: A speed control apparatus for a synchronous reluctance motor is disclosed. The speed control apparatus includes a voltage detector for detecting a voltage applied to the motor, a first phase converter for receiving voltages in three phases from the voltage detector and converting the three-phase voltages into equivalent voltages in two phases, a current detector for detecting a current applied to the motor, a second phase converter for receiving currents in three phases from the current detector and converting the three-phase currents into equivalent currents in two phases, and a rotor speed operator for receiving the two-phase voltages thereby computing a speed of a rotor included in the motor. A speed controller for receiving a deviation between a speed command externally inputted and an output value from the rotor speed operator is provided for generating a torque-related current command.

Abstract: The present invention relates to a driving of a switched reluctance motor, and in particular to a driving device for an SR motor which can detect a position of a rotor of the SR motor by using a smaller number of sensors than phases, and which can drive the SR motor on the basis of the detected result. At an initial stage of the starting of the SR motor, the position detection is not performed, and a microprocessor sequentially outputs a plurality of control signals, thereby aligning the rotor. After the starting, the microprocessor sequentially outputs the plurality of control signals according to a result detected from a position detection unit.

Abstract: A combined drive circuit for a split brake system of a motor vehicle has a switched reluctance motor and a brush motor. The switched reluctance motor has multiple phase windings. The combined drive circuit includes a DC power source with first and second supply buses. A SR motor driver supplies current to the switched reluctance motor. The SR motor driver has a first capacitor coupled to the phase windings for storing energy from the phase windings and a second capacitor coupled to the first capacitor and a third supply bus, thereby developing a third supply bus voltage across the second capacitor. A brush motor driver is coupled to the first and second capacitor. The SR motor driver is adapted to supply current to the brush motor. The brush motor driver includes first, second, third and fourth switching elements coupled to the brush motor.

Abstract: A combined drive circuit for a split brake system of a motor vehicle has a switched reluctance motor and a brush motor. The switched reluctance motor has multiple phase windings. The combined drive circuit includes a DC power source with first and second supply buses. A SR motor driver supplies current to the switched reluctance motor. The SR motor driver has a first capacitor coupled to the phase windings for storing energy from the phase windings and a second capacitor coupled to the first capacitor and a third supply bus, thereby developing a third supply bus voltage across the second capacitor. A brush motor driver is coupled to the first and second capacitor. The SR motor driver is adapted to supply current to the brush motor. The brush motor driver has a first switching element and a second switching element coupled to the brush motor.

Abstract: A combined drive circuit for a split brake system of a motor vehicle has a switched reluctance motor and a brush motor. The switched reluctance motor has multiple phase windings. The combined drive circuit includes a DC power source with first and second supply buses. A SR motor driver supplies current to the switched reluctance motor. The SR motor driver has a first capacitor coupled to the phase windings for storing energy from the phase windings and a second capacitor coupled to the first capacitor and a third supply bus, thereby developing a third supply bus voltage across the second capacitor. A brush motor driver is coupled to the first and second capacitor. The SR motor driver is adapted to supply current to the brush motor. The brush motor driver includes first, second, third and fourth switching elements coupled to the brush motor.

Abstract: A combined drive circuit for a split brake system of a motor vehicle has a switched reluctance motor and a brush motor. The switched reluctance motor has multiple phase windings. The combined drive circuit includes a DC power source with first and second supply buses. A SR motor driver supplies current to the switched reluctance motor. The SR motor driver has a first capacitor coupled to the phase windings for storing energy from the phase windings and a second capacitor coupled to the first capacitor and a third supply bus, thereby developing a third supply bus voltage across the second capacitor. A brush motor driver is coupled to the first and second capacitor. The SR motor driver is adapted to supply current to the brush motor. The brush motor driver has a first switching element and a second switching element coupled to the brush motor.

Abstract: A switched reluctance drive is supplied from a power source and has a DC link capacitor. The phases of the machine are controlled by a current chopping controller which, during phase conduction overlap, controls the initiation of chopping in a second phase so as to minimize the current drawn from the capacitor, thereby allowing a reduction in the capacitor rating.

Abstract: A polyphase switched reluctance machine is controlled by a control system using sensorless position detection. The controller is robust and reliable and operates over the entire current chopping range of the machine. Diagnostic pulses of predetermined flux-linkage are injected into a phase, whether or not it has residual current flowing.

Abstract: A speed control apparatus of a synchronous reluctance motor includes: a rectifier for receiving an AC power and rectifying it to a DC power; an inverter for receiving a DC power to an AC power and supplying it to a synchronous reluctance motor; a detecting unit for detecting a current and a voltage supplied to the synchronous reluctance motor, operating the generated induction voltage and the estimated induction voltage generated from the current, and generating an estimated angular velocity of the synchronous reluctance motor; and a controller for receiving the estimated angular velocity and the velocity command value inputted by a user and controlling the speed of the synchronous reluctance motor through the inverter Since the speed of the synchronous reluctance motor is controlled by detecting the current and the voltage supplied to the synchronous reluctance motor, rather than using an encoder or a hall sensor, a production cost of the synchronous reluctance motor can be reduced.

Abstract: The method of controlling a converter of a switched reluctance machine includes clocking a power switch with a frequency that depends on the width of the hysteresis band. The hysteresis width is varied according to reluctance machine speed, especially so that a difference between maximum and minimum values with which the current is switched on and off either increases with decreasing speed, decreases with increasing load, or both. The changing of the hysteresis width occurs so that a difference between maximum and minimum threshold values either increases with decreasing speed, decreases with increasing load, or both. The width of the hysteresis band preferably varies linearly with speed, load and/or current, especially so that the width of the hysteresis band varies linearly so that the clocking frequency is maintained substantially constant. Also targeted changes in the width of the hysteresis band are made to move the clocking frequency from near noise-critical resonance frequencies.

Abstract: In a method of operating and controlling hysteresis motors energized by a three-phase power supply and individually monitored by an operating monitoring system, whereby the effective power output of the individual motors is determined and the three-phase voltage is changed if the effective power output deviates from a predetermined range, the hysteresis motors are first energized at an intermediate range voltage until they reach nominal speed and are then running at synchronous speed, the supply voltage is then increased to an upper range, where the remanent magnet pole strength is impressed on the armature and then reduced to a lower range for continuous operation of the motors, the power output of the individual motors is monitored and, if it drops below a threshold indicating a switch to asynchronous operation, the operating voltage is again increased to the intermediate range for renewed synchronization.

Abstract: Motor control of a variable reluctance motor is obtained by providing a periodic voltage waveform to a coil of a motor. No coil current control or current or flux feedback is needed to obtain flux waveforms that allow for low-distortion or distortion-free operation of the motor. The periodic voltage waveform may be a sinusoidal or sawtooth signal, for example, and has a substantially zero mean for each cycle of the signal. The periodic voltage waveform may be offset to compensate for the resistance of the coil, and the coil current may be monitored in order to determine the amount of offset required. By providing a zero-mean or substantially zero-mean periodic voltage waveform, the coil current and flux in the gap between the core and the moving part are guaranteed to reach a zero value at some point during each period (or cycle) of the periodic voltage waveform.

Abstract: A motor current detection amplifier detects a motor current's areas in two phase periods with reference to a motor voltage. A controlling microcomputer computed the ratio of the motor current areas of the two phase periods and provides the same as phase difference information which is in turn used to control a motor drive voltage to apply a sine wave of a predetermined period to the motor's coil to allow 180°-driving including a sine wave conduction resistant to noise and achieving a reduced cost hike.

Abstract: A two-phase switched reluctance motor comprises a rotor without windings, a stator having windings, and an electronic control circuit for controlling the current in the windings to effect rotation of the rotor. The control circuit includes a capacitance bridge defining a floating point to which one end of each of the windings is coupled to form a resonance circuit. Switching transistors are connected to the windings and are switched in synchronism with rotation of the rotor so as to produce current pulses which are limited by the build-up of voltage at the floating point of the capacitance bridge. This ensures that the current in the windings returns naturally to zero at the end of each excitation pulse, thus providing more efficient power operation and reducing the acoustic noise of the machine.

Abstract: In order to make an electric motor smooth in drive with improving the electric consumption efficiency, the over heat of a motor driver and vibrations thereat are restricted which result from chopping energization of the electric motor.