Abstract: In one embodiment, a method includes measuring between two consecutive electrical commutations of a brushless direct-current (BLDC) motor a current through the BLDC motor. One or more pulse-width-modulation (PWM)-configurable signals are driving the BLDC motor. The method includes determining a waveform of the current through the BLDC motor; if the waveform of the current through the BLDC motor comprises a first type, then increasing a duty cycle of each of one or more of the PWM-configurable signals driving the BLDC motor; and, if the waveform of the current through the BLDC motor comprises a second type, then decreasing a time interval between electrical communications of the BLDC motor.

Abstract: A motor control device has a motor driving circuit for driving a motor, a current detection circuit for detecting a motor current flowing through the motor driving circuit, and a controller for calculating a detected value of the motor current based on an output of the current detection circuit, comparing the detected value with a target value of the motor current, and generating a command value for allowing a motor current of the target value to flow through the motor based on a deviation therebetween, to output the command value to a motor driving circuit. The current detection circuit is configured of a first current detection circuit having a positive first gain and a second current detection circuit having a negative second gain obtained by inverting the first gain.

Abstract: The present invention discloses a mechanical equipment. The sensing member and the sensed member are mounted on the power device, and one of the sensing member and the sensed member is mounted on the output mechanism to move periodically as the output mechanism moving periodically. When each time the sensing member and the sensed member are located relatively at a predetermined position, the control device receives the sensing signal generated when the sensing member senses the sensed member and sends a predetermined control command to the power mechanism when the sensing signals received by the control device reach the threshold value. Therefore, the present invention can achieve controlling the working state of the mechanical equipment and reduce the failure probability of the mechanical equipment at the same time.

Abstract: A current limiting device includes a switching portion, a reflux portion connected to a connection point of the switching portion and an output terminal, and supplying a current to a motor generator while the switching portion is cutting off the current, a current measurement portion that measures the current flowing from the output terminal to the motor generator, and a current control portion that controls the switching portion to switch ON/OFF according to a current value measured by the current measurement portion. When the motor generator is motor-driven using electric power of a condenser, the current control portion limits the current to the motor generator by controlling the switching portion to switch ON/OFF in a case where the measured current value is equal to or exceeds a predetermined current value.

Abstract: A control system for a motor includes an inverter coupled to the motor. The control system further includes a microcontroller coupled to the inverter. The microcontroller includes a processor programmed to measure an input voltage and acquire a back EMF voltage of the motor. The processor is also programmed to control the inverter to regulate the motor voltage based on the input voltage and the back EMF voltage to facilitate controlling the motor.

Abstract: Embodiments of the present disclosure relate to methods, systems and apparatus for generating voltage command signals for controlling operation of an electric machine. The disclosed embodiments can reduce current and torque oscillation, which can in turn improve machine efficiency and performance, as well as utilization of the DC voltage source.

Abstract: A power supply unit for a press machine having a converter (converter circuit) connected to a commercial AC power supply, and an inverter (inverter circuit) connected to a press motor, includes an electrical energy bank, an inrush prevention circuit, an inrush prevention instruction signal generation section, and a contactor switch section, wherein contactors of the inrush prevention circuit are switched from on ON state to an OFF state and inrush prevention resistors of the inrush prevention circuit are connected to AC phase current paths on condition that the inrush prevention instruction signal generation section has generated and output an inrush prevention instruction signal (Sres) during press operation.

Abstract: A motor control system is provided, including a motor and a control module. The motor operates at a rotational velocity, and creates a regenerative current. The motor has a target field weakening current that is configured for limiting the regenerative current to a threshold value. The control module is in communication with the motor. The control module receives a motor torque command. The control module includes control logic for identifying the target field weakening current based upon the motor torque command and the rotational velocity of the motor.

Abstract: A motor includes a rotor and a plurality of pairs of electromagnets. The energy needed for alignment of the rotor is used to generate the first movement in forced commutation and may be combined with the initial energy to start the motor. The logic is configured to align the rotor by energizing the three coils of the motor. PWM is applied to the first coil to control current on the coils; when a maximum PWM duty cycle is reached, the coil not required to rotate the correct direction are released, thereby initiating motion in a rotor. A rotation period is determined. One or more pairs of electromagnets are excited at a first excitation level which may be increased, over a second period, to a second level. The second level may be a higher level than the first level. The rotation period may be decreased over the first and second periods.

Abstract: A command rotation speed is set to an initial rotation speed, and a forced commutation mode is started. In the forced commutation mode, a rotation speed is increased by a predetermined increase amount each time and forced commutation is executed until the rotation speed reaches a set rotation speed. Then, a switchover to the sensorless control mode is made when the rotation speed reaches the set rotation speed (S4) and a rotor position becomes detectable.

Abstract: A lock state occurrence determination apparatus includes a counter, a reset device, a reference time changing device, a lock state determination device, and an invalidation device. The invalidation device performs, in a case where a false determination of occurrence of a lock state of a motor is caused by the lock state determination device due to an operation input to operate a rotation speed of the motor, at least one of a first invalidation operation to invalidate the lock state determination device and a second invalidation operation to invalidate continuation of a counting operation by the counter.

Abstract: In a power conversion apparatus, a main switching element in one main circuit is controlled to repeat an on-off state, and a diode in the other main circuit is used as a freewheeling diode. Multiple snubber circuits each having a resistor, a capacitor, and a second switching element which are serially coupled are coupled in parallel to the main circuit. The second switching elements are turned-on sequentially before the turn-on or turn-off of the main switching element that repeats the on-off state.

Abstract: A torsional mode damping controller system is connected to a converter or placed inside the converter. The converter is driving a drive train including an electrical machine and a non-electrical machine. The controller system includes a first input interface configured to receive a first digital signal from a first phase lock device or a first dynamic observer, a second input interface configured to receive a second digital signal from a second phase lock device or a second dynamic observer, and a controller connected to the first and second input interfaces. The controller is configured to receive the first and second digital signals, compare the first digital signal with the second digital signal, generate control data for a rectifier and/or an inverter of the converter, and send the control data to the rectifier and/or to the inverter.

Abstract: An inverter device includes a plurality of switching circuits in which first switching elements including Si semiconductors and second switching element including WBG semiconductors having ON resistance smaller than that of the first switching elements and having switching speed higher than that of the first switching elements are connected in parallel. The inverter device includes a converting circuit that converts a direct-current voltage into a desired alternating-current voltage and a driving unit that generates a plurality of driving signals for respectively turning on and off the switching circuits. The inverter device includes, for each of the switching circuits, a gate circuit that, based on the driving signals, turns on the second switching element later than the first switching element and turns off the first switching element later than the second switching element.

Abstract: A motor drive device has an inverter circuit, in which at least three sets of a pair of upper and lower arms including a semiconductor switching element on an upper arm and a lower arm is arranged, for supplying voltage to a motor based on ON/OFF operation of each semiconductor switching element by a PWM (Pulse Width Modulation) signal, an inverter drive unit for outputting the PWM signal to each semiconductor switching element of the inverter circuit, a fail safe circuit, arranged between the inverter circuit and the motor, including a semiconductor switching element for shielding the voltage supply from the inverter circuit to the motor for each phase, and a fail safe drive unit for outputting a signal for turning ON/OFF the semiconductor switching element of the fail safe circuit.

Abstract: An electric motor that includes an electronic motor controller is described. The electronic motor controller includes a motor management circuit and a power supply circuit physically separate from the motor management circuit. The motor management circuit includes an insulated metal substrate, driver components operably attached to the insulated metal substrate and operable to provide output signals for application to windings of the electric motor, at least one current sensor operable for sensing an amount of current applied to the windings of and electric motor, and at least one control device operably attached to the insulated metal substrate for controlling operation of the driver components. The power supply circuit includes a composite circuit card and power processing components operably attached to the circuit card and operable to convert an input voltage into at least one output voltage to be supplied to the motor management circuit.

Abstract: In a control apparatus for an AC electric motor, a dq axis current feedback control unit 44 and a qn axis current feedback control unit 46 execute a feedback control of higher harmonic components of actual currents id and iq flowing in an AC electric machine 10 to higher harmonic current instruction values ?idkr and ?iqkr. A d axis current instruction value adjusting unit 24 and a q axis current instruction value adjusting unit 26 add the higher harmonic current instruction values ?idkr and ?iqkr to fundamental current instruction values idr and iqr. Ad axis current feedback control unit 32 and a q axis current feedback control unit 34 execute a feedback control of a difference between the actual currents id and iq and the sum of the higher harmonic current instruction values ?idkr, ?iqkr and the fundamental current instruction values idr and iqr into zero.

Abstract: A power supplied by an AC power supply is used as an input to a rectifying circuit, and an output of the rectifying circuit is used as an input to a smoothing capacitor having a capacitance of about 1/100 of the capacitance of conventionally used capacitance. The capacitor is provided between a positive electrode node and a negative electrode node located between bus lines of output of rectifying circuit. Diodes constituting a rectifying circuit are connected respectively with phase outputs of an inverter. The rectifying circuit is connected to the negative electrode node through a capacitor. The rectifying circuit is connected such that an electric current flows only in the direction from an output of the inverter to the capacitor. The load is connected in parallel with capacitor.

Abstract: A method for operating a motor of a motor-driven power steering (MDPS) includes: generating, by an inverter operating unit, a two-phase operation command by projecting a Q-axis command onto a two-phase operation axis, when an error occurs in any one of three phases; converting, by the inverter operating unit, coordinates of the two-phase operation command into an actual operation axis; calculating, by the inverter operating unit, a two-phase operation voltage by performing proportional integral (PI) control on the two-phase operation command converted into the actual operation axis; and operating, by the inverter diving unit, a motor by applying the two-phase operation voltage to an inverter unit.

Abstract: A motor drive controller to control a motor via multiple sensors includes a first phase detector to compare respective differential pairs of the sensor signals from the same sensor to detect phases of the rotor, and output a first phase information signal; a second phase detector to compare a respective one of the multiple sensor signals with another sensor signal from the different sensor to detect the phases and output a second phase information signal; a phase divider to divide the phases, detected by the first and second phase detectors, into multiple predetermined phase intervals; a signal selector to select one of the multiple sensor signals in the multiple predetermined phase intervals; and a third phase detector to detect whether the signal selected by the signal selector reaches a predetermined threshold level corresponding to a predetermined phase of the rotor, and output a third phase information signal.

Abstract: Provided is a motor driving device. The motor driving device includes a drive signal generating unit, a current control unit, and a driving unit. The drive signal generating unit generates a motor drive signal for driving a motor. The current control unit is disposed at a front of the drive signal generating unit and controls a current of the drive signal generating unit so as to prevent noise and vibration of a motor caused by electromagnetic interference generated when a switch of the drive signal generating unit is turned on/off. The driving unit drives the motor based on the motor drive signal outputted from the drive signal generating unit.

Abstract: A motor drive controller to drive a motor, based on multiple sensors that generates multiple sensor signals corresponding to different positions of the rotor; including a first phase detector to compare a respective one of the multiple sensor signals with a paired sensor signal from the same sensor to detect phases of the rotor, and output a first phase information signal representing a first detected phase; a phase divider to divide the phases, detected by the first phase detector into multiple predetermined phase intervals; a signal selector to select one of the respective multiple sensor signals from the multiple sensors in the multiple predetermined phase interval; and a second phase detector to detect whether the signal selected by the signal selector reaches a predetermined threshold level corresponding to a predetermined phase of the rotor, and output a second phase information signal representing a second detected phase.

Abstract: A system. The system includes a processor, a first module, a second module and a third module. The first module is communicably connected to the processor and is configured for calculating a q-axis voltage component and a d-axis voltage component. The second module is communicably connected to the processor and is configured for determining a voltage angle relative to the q-axis. The third module is communicably connected to the processor and is configured for (1) comparing the determined voltage angle to a predetermined value, (2) outputting the determined voltage angle if the determined voltage angle is less than the predetermined value, and (3) outputting the predetermined value if the predetermined value is less than the determined voltage angle.

Abstract: Disclosed is an angle detection device including plural sensors that output corresponding sinusoidal signals, wherein each of the sinusoidal signals varies sinusoidally depending on a rotational angle of a rotor of a motor, and each of the sinusoidal signals has a phase that depends on a position of the corresponding sensor; a vector generating unit that generates a vector represented by a result of mutually operating at least two of the sinusoidal signals; a vector rotation unit that rotates the vector by operating the vector and reference sine waves having corresponding phases; and an angle search unit that causes the vector rotation unit to sequentially rotate the vector until a phase of the vector becomes a predetermined phase, and that detects an angle between the vector prior to being rotated and the predetermined phase as the rotational angle of the rotor of the motor.

Abstract: A rotary electric machine includes: a stator having a stator winding and a stator core; a rotor having a first magnetic pole section and a second magnetic pole section, where the second magnetic pole section rotates respective to the first magnetic pole section; a shaft provided for the rotor; and a rotary mechanism configured to rotate the second magnetic pole section about the shaft. The rotary mechanism includes: a moving member configured to be movable along the shaft; a lead screw mechanism configured to move the moving member along the shaft; and a rotary member configured to rotate respective to the shaft along with the second magnetic pole section, where the rotary member engages the moving member and the second magnetic pole section.

Abstract: A soft switching control circuit for a DC motor is provided. The soft switching control circuit has an absolute value generating circuit, a threshold voltage generating circuit, and a comparing circuit. The absolute value generating circuit outputs an absolute value signal according to a pair of Hall signals from the DC motor. The threshold voltage generating circuit receives a detected state signal and at least an end voltage of a coil of the DC motor for determining a current on the coil at an actual state change time defined by the detected state signal. According to the determination, the threshold voltage generating circuit outputs a threshold voltage with an adjusted voltage level. The comparing circuit compares the absolute value signal and the threshold voltage so as to generate a state change adjusting signal for modifying the actual state change time.

Abstract: A microcontroller determines the position of the rotor of a brushless, direct-current motor by determining the time of zero crossing of back electromotive force (EMF) emanating from the non-driven phase winding. The zero crossing point is determined by interpolating voltage differentials that are time stamped. Each voltage differential is the difference between the phase voltage of the phase winding and the motor neutral point voltage. The time of zero crossing is determined without using a comparator and without interrupting the processor at each zero crossing point. The processor interpolates the time of zero crossing independently of when the zero crossing point occurs. A hold signal conductor is connected both to a sample and hold circuit and to the load input lead of a time stamp register. The microcontroller simultaneously captures a phase voltage in the sample and hold circuit and a timer count in the time stamp register.

Abstract: A method for determining a direction of rotation for an electronically commutated motor (ECM) is described. The motor is configured to rotate a blower and the method comprises rotating the blower using the ECM and determining if the resulting blower rotation is indicative of the desired direction of rotation for the blower.

Abstract: A permanent-magnet AC motor comprises a motor and a controller coupled to the motor. The motor includes a winding. The controller includes a drive model configured to provide a drive current. Waveform of the drive current is spatially symmetrical. The winding has a waiting zone having electrical angle of 30° and a driving zone having electrical angle of 150° in each half electrical cycle when the motor is in operation. The driving zone is equally divided into five driving sub-zones.

Abstract: An HVAC control system, associated brushless direct current motor, and methods of operation are disclosed. One such control system includes a brushless direct current motor and an optically-isolated interface exposing control access to the brushless direct current motor. The system includes a first programmable controller electrically connected to the brushless direct current motor, the programmable controller configured to receive a control signal via the optically-isolated interface, and a second programmable controller providing the control signal to the optically-isolated interface.

Abstract: Embodiments of the invention provide a fire-extinguishing system and method for injecting foamant into a stream of water. The system can include a flow meter determining a flow rate of the stream of water and a foam pump having an inlet coupled to a supply of foamant and an outlet coupled to the stream of water. The system includes a servo motor driving the foam pump. The servo motor includes a sensor used to determine a rotor shaft speed and/or a rotor shaft torque.

Abstract: A detection control system includes a sensing unit, a control module and a driving module for a motor including a rotor and a stator. The sensing unit electrically connects the motor to sense a first and a second magnetic pole of the rotor cross a chip disposed between the rotor and the stator; a third magnetic pole is alternated to a forth magnetic pole of the stator to generate a sensing signal. A detection unit of the control module detects a kickback voltage value generated by a first current value changing to a second current value to calculate a minimum current value to generate a detecting signal. A timing unit receives the sensing and the detecting signal to calculate a first and a second period of time, and a discharging time. The driving module drives the rotor by receiving a control signal the control unit generates by controlling an alternating time.

Abstract: In an electric hair cutter and a control method for its motor rotational speed, the electric hair cutter includes a main body, a BLDC (brushless DC) motor, a power source, a detecting unit, an electrical energy adjusting unit and a control module. The main body has a cutting unit. The BLDC motor drives the cutting unit. The detecting unit can detect the counter-electromotive force of the BLDC motor. The control module may receive the counter-electromotive force signals detected by the detecting unit and may control the electrical energy adjusting unit according to the counter-electromotive force signals so as to keep the BLDC motor rotating at a fixed RPM.

Abstract: A method for controlling a specific electric machine includes receiving with a controller a back electromotive force (BEMF) coefficient for the specific electric machine. The controller is configured to control operation of an inverter coupled to the electric machine where the inverter is configured to provide or receive multi-phase electricity to or from the electric machine in motor mode or generator mode, respectively. The method further includes receiving with the controller an input related to a selected torque to be applied by or a selected power to be removed from the electric machine. The method further includes determining a first electrical parameter the inverter is to apply to in motor mode or a second electrical parameter the inverter is to convert power to in generator mode using the BEMF coefficient, and applying the first electrical parameter to the electric machine or converting the received power to the second electrical parameter.

Abstract: A method of controlling an electrical machine that includes selecting an edge of a rotor-position signal as a reference edge and commutating a phase winding of the electrical machine at times relative to the reference edge. The rotor-position signal has at least four edges per mechanical cycle, each of the edges being associated with a respective zero-crossing in back EMF or minimum in inductance of the phase winding. The angular position of at least one of the edges relative to its respective zero-crossing or minimum is different to that of the other edges. The reference edge is then selected from the edges such that the angular position of the reference edge relative to its respective zero-crossing or minimum is the same with each power on of the electrical machine. Additionally, a controller and control system that implement the method.

Abstract: A motor control device has a motor driving circuit for driving a motor, a current detection circuit for detecting a motor current flowing through the motor driving circuit, and a controller for calculating a detected value of the motor current based on an output of the current detection circuit, comparing the detected value with a target value of the motor current, and generating a command value for allowing a motor current of the target value to flow through the motor based on a deviation therebetween, to output the command value to a motor driving circuit. The current detection circuit is configured of a first current detection circuit having a positive first gain and a second current detection circuit having a negative second gain obtained by inverting the first gain.

Abstract: In a system, a superimposing element sets a command value vector of a high-frequency voltage signal and superimposes the high-frequency voltage signal with the command value vector on an output voltage of an inverter. The high-frequency voltage signal has a frequency higher than an electrical angular frequency of a rotary machine. The command value vector is correlated with a measured high-frequency component value of a current signal flowing in the rotary machine. A calculating element calculates a rotational angle of the rotary machine based on the measured high-frequency component value of the current signal flowing in the rotary machine. A reducing element controls at least one of the inverter and a direct voltage power supply to reduce a difference due to the dead time between the command value vector and a vector of a high-frequency voltage signal to be actually superimposed on the output voltage of the inverter.

Abstract: A control command generator that generates an armature interlinkage flux command and a torque current command by a torque command, a rotation speed, and an operation target command, includes a first flux command generator generating a first flux command by the toque command or the torque current command, a second flux generator generating a second flux command by the torque command or the torque current command and the rotation speed of the synchronous machine, a command allocation setting unit setting an allocation coefficient equivalent to an allocation ratio of the two first and second flux commands by the operation target command, a flux command adjuster outputting an armature interlinkage flux command by the two flux commands and the allocation coefficient, and a torque current command generator generating the torque current command by the torque command and the armature interlinkage flux command.

Abstract: A method for driving a motor is provided. Pulse width modulation (PWM) signals are generated from a voltage signal and a commanded angle signal, which drives a motor with multiple phases. A motor current from a motor is measured with a single shunt and converted into a digital signal. Based on the digital signal and the commanded angle signal, direct-axis and quadrant-axis currents for the motor can be determined, and the voltage signal and the commanded angle signal can be adjusted based at least in part on the direct-axis and quadrant-axis currents.

Abstract: Embodiments of the present disclosure relate to methods, systems and apparatus for controlling operation of an electric machine in a vector controlled motor drive system when the electric machine operates in an overmodulation region. The disclosed embodiments can reduce variations/errors in the phase voltage command signals applied to the multi-phase machine so that phase current may be properly regulated thus reducing current/torque oscillation, which can in turn improve machine efficiency and performance, as well as utilization of the DC voltage source.

Abstract: Disclosed is a power supply module for a hall sensorless BLDC motor, including: a high-voltage/large-current power device t applied with high voltage/large current and including a plurality of power devices driving the hall sensorless brushless direct current (BLDC) motor; a motor driving circuit sensing and controlling a positional signal or a velocity signal of the hall sensorless BLDC motor and generating a PWM control signal for controlling the hall sensorless BLDC motor; and a power device driving circuit driving the high-voltage/large-current power device according to the PWM control signal of the motor driving circuit, wherein the high-voltage/large-current power device, the power device driving circuit, and the motor driving circuit are CMOS-integrated on the same substrate.

Abstract: In an electric power steering system, a back electromotive force constant is calculated on the basis of a steering angular velocity and an estimated induced voltage. Then, a rotation angular velocity of a motor is calculated as an estimated rotation angular velocity on the basis of a motor current, a motor voltage, the back electromotive force constant and a motor resistance.

Abstract: A device and method to determine the stopping rotor position of a washing machine motor includes an inverter, a permanent magnet synchronous motor, and an electronic motor controller. The controller determines the stopped rotor position of the motor by measuring induced currents in the stator field coils of the motor. While the motor is de-energized and slowly rotating, the controller directs the inverter to connect all of the stator field coils of the motor together. The stator field coils may be connected to a common D.C. rail, output from an A.C.-D.C. converter of the washing machine. In an embodiment, the controller determines the rotor position based on the polarities of current induced in the stator field coils. In another embodiment, the controller determines the rotor position based on the phase angle and angular frequency of the three phase currents, transformed into a stationary reference frame.

Abstract: The invention relates to an electric motor assembly, particularly for driving a fan for an engine cooling system and/or an air conditioner of a motor vehicle, comprising an electric motor and a motor control device for activating the electric motor. According to the invention, the motor control device can be adjusted according to a characteristic curve (1,2,3,4) of the electric motor and/or of the fan, and thereby the power and/or rotational speed of the electric motor can be adjusted.

Abstract: A current sensor detects a bus current flowing to an inverter. An estimation section uses actual currents id and id outputted from a d-q conversion section as initial values, estimates currents flowing in a motor/generator and calculates estimated currents ide and iqe. A UVW conversion section converts the estimated current ide and iqe to three phase currents. A selection section inputs, as currents flowing in each phase of the motor/generator, three out of outputs of the UVW conversion section and the bus current. The bus current is used as the current of one phase, if a voltage vector representing an operation state of the inverter is an effective voltage vector.

Abstract: A method for monitoring input power to an electronically commutated motor (ECM) is described. The method includes determining, with a processing device, an average input current to the motor, the average input current based on a voltage drop across a shunt resistor in series with the motor, measuring an average input voltage applied to the motor utilizing the processing device, multiplying the average input current by the average voltage to determine an approximate input power, and communicating the average input power to an external interface.

Abstract: A method for driving a brushless motor including a first coil and a second coil for two phases but does not include a coil for one of three phases. A three-phase inverter circuit is connected to the first coil and the second coil. Currents having a phase difference corresponding to an electrical angle of 60 degrees are applied to the first coil and the second coil to generate a circular rotating magnetic field.

Abstract: Some embodiments provide a system that generates a coil switching signal for a brushless DC motor. During operation, the system determines a magnetic field of the brushless DC motor at a first time and a magnetic field of the brushless DC motor at a second time. Then, the coil switching signal is generated based on a relationship between the magnetic field determined at the first time and a first predetermined threshold, and the magnetic field determined at the second time and a second predetermined threshold.

Abstract: A method for operating an electric motor with primary and secondary sections, wherein the primary section has a multi-phase exciter winding, each of the phase connections of said exciter winding being connected to an output connection of an end stage, which has controllable semi-conductor switches for applying phase voltages to the output connections, includes the following steps: a) introducing an operating phase by applying the phase voltages to the output connections such that a moving magnetic field is induced in the exciter winding, the moving field effecting a relative motion between the primary and secondary sections, b) hinting off the phase voltage at least one of the output connections to introduce a measurement phase, and c) measuring the electrical back emf induced in the winding strand in order to determine the angular difference between the phase position of the exciter current and that of the back emf.

Abstract: An energization control circuit compares a target rotation direction of a motor and an actual rotation direction of a motor detected based on rotation detection sensors. If the compared rotation directions are in disagreement, the energization control circuit switches over an inverter control mode from 120-degree energization to 180-degree energization to extend an on-period of a high-side switching element of an inverter circuit to an advance phase side. Thus, the high-side switching element is turned on, when a low-side switching element of the same phase is in a turned-off state. A free-wheeling current is allowed to flow through the high-side switching element rather than through a free-wheeling diode of the high-side switching element.