A motor drive circuit includes: a PWM signal generation part configured to generate a PWM signal based on a count value of a counter; a detection part configured to detect a zero crossing of a counter electromotive voltage generated in a coil of a motor; a prediction part configured to predict an arrival timing of the zero crossing of the counter electromotive voltage; a stop part configured to stop a counting operation of the counter after a first time point going back from the arrival timing predicted by the prediction part; and a reset part configured to reset the count value at a timing at which the detection part detects the zero crossing of the counter electromotive voltage.

A motor drive circuit includes: a PWM signal generation part configured to generate a PWM signal based on a count value of a counter; a detection part configured to detect a zero crossing of a counter electromotive voltage generated in a coil of a motor; a prediction part configured to predict an arrival timing of the zero crossing of the counter electromotive voltage; a stop part configured to stop a counting operation of the counter after a first time point going back from the arrival timing predicted by the prediction part; and a reset part configured to reset the count value at a timing at which the detection part detects the zero crossing of the counter electromotive voltage.

A motor system comprises a motor comprising: a stator with a plurality of subwindings each having a plurality of phase connections for receiving phase voltages, wherein each of the subwindings is electrically insulated from each of the other subwindings; a rotor comprising a plurality of permanent magnets or energisable electromagnets; a controller comprising a plurality of control parts, each control part associated with a respective subwinding, each control part being configured to monitor phase voltages of the associated subwinding, between phase connections. The system further comprises a controller configured to: obtain, from each control part, at set discrete time intervals, a plurality of back measured electromotive force, EMF, readings for each of the respective subwindings; using the plurality of measured back EMF readings and an a priori knowledge of the motor's construction to estimate a commutation event timing.

Ina power conversion system having a fixed pulse pattern modulation unit 2 that is configured to refer to tables storing therein pulse patterns that determine respective command voltage levels corresponding to phase information for each modulation ratio and to generate a gate signal g on the basis of a command modulation ratio d and a control phase θ and driving a power converter 3 on the basis of the gate signal g, the fixed pulse pattern modulation unit 2 is further configured to, when performing a pulse pattern transition, search for a proper post-transition table reference position and make a command voltage level follow a command voltage level of a post-transition pulse pattern. With this, the power conversion system that can perform the pulse pattern transition without current impulse and that can also be applied to a multi-level power converter having four levels or more can be provided.

A sliding door driving device includes: a power source; a motor that outputs power to open and close the door; a motor driving circuit that connects the power source and the motor to each other; and a motor control device that controls the motor driving circuit. The motor control device includes an inverter that converts DC power supplied from the power source into AC power, and a shunt resistor disposed between the power source and the inverter. The position detection unit of the motor control device obtains the rotation angle of the motor based on the output of the shunt resistor.

A motor drive control device 1_2 includes a target point determination unit 12_2 determining a target point P of zero crossing of a coil current Iu of a U phase based on a position detection signal Shu, a current zero crossing point estimation unit 14_2 estimating a zero crossing point Q of the coil current Iu of the U phase by detecting a change in a current direction of the coil current Iu of the U phase at a predetermined timing in every cycle of a PWM signal, an adjustment instruction signal generation unit 19_2 generating at least one of a phase adjustment instruction signal Sp for instructing phase adjustment of the coil current Iu and a frequency adjustment instruction signal Sf for instructing frequency adjustment of the PWM signal according to a phase difference Δφ between the target point P and the zero crossing point Q such that the phase difference is within a predetermined range, and a drive control signal generation unit 16_2 generating a drive control signal Sd based on at least one of the phase adjustment instruction signal Sp and the frequency adjustment instruction signal Sf.

An object of the present invention is to effectively reduce vibration or noise caused by a motor. An inverter circuit 300 generates an alternating current from a direct current supplied from a direct current power supply 10 by using a plurality of IGBTs 311 which are switching elements, supplies the generated alternating current to a motor 100, and drives the motor 100. This alternating current includes a fundamental harmonic current corresponding to a rotational speed of the motor 100, and a harmonic current of a switching operation of the IGBTs 311. A controller 200 controls a second phase such that a first phase and the second phase are not superimposed on each other at a predetermined motor rotational speed, the first phase being a phase of an excitation force cyclically produced in the motor 100 by the fundamental harmonic current, and the second phase being a phase of an excitation force cyclically produced in the motor 100 by the harmonic current.

A motor commutation waveform generating circuit is provided. The motor commutation waveform generating circuit includes: an edge detection circuit, configured to receive sensing signals of the motor and derive a clock signal indicating a commutation switching point of the motor; an angle cutting circuit, controlled by the clock signal to generate an angle indication pulse indicating a rotation angle of the motor; a synthetic wave generating circuit, using the angle indication pulse to sequentially change waveform voltages corresponding to required angles and output them in segments; and a signal combining circuit, controlled by the clock signal to combine waveform voltage signals generated by the synthetic wave generating circuit, thereby obtaining a plurality of synthetic waveforms provided to a drive control system of the motor for drive control after pulse width modulation.

A control chip, a control system, and a control method for a motor are disclosed. The control chip comprises: an analog comparator comprising a first input terminal and a second input terminal, wherein the first input terminal receives a reference voltage of the motor, the second input terminal receives at least one back EMF (Electromotive Force) of the motor in turn, the analog comparator compares each of the at least one back EMF with the reference voltage in turn through a polling method, so as to produce at least one comparison result and control the motor according to the at least one comparison result. Thereby, the analog comparator is able to compare back EMF with the reference voltage without three comparators, and the cost is therefore saved.

A shift range control apparatus switches a shift range by controlling a motor. The shift range control apparatus includes an angle calculator, a speed calculator and a drive controller. The angle calculator calculates a motor angle based on a detected value of a rotational angle sensor. The speed calculator calculates a motor rotational speed based on the detected value of the rotational angle sensor. The drive controller executes a stationary phase energization control to stop the motor in response to the motor angle reaching a stationary phase energization start position. The drive controller sets a stationary energization phase being a stationary phase of the motor in the stationary phase energization control, according to the motor rotational speed when the motor angle reaches the stationary phase energization start position.