A power system including a power converter system and an electric machine is provided. In one aspect, the power converter system has first and second switching elements. The electric machine includes a first multiphase winding electrically coupled with the first switching elements and a second multiphase winding electrically coupled with the second switching elements. The first and second multiphase windings are arranged and configured to operate electrically opposite in phase with respect to one another. One or more processors control the first switching elements to generate first pulse width modulated (PWM) signals based on received voltage commands to render a first common mode signal and also control the second switching elements to generate second PWM signals based on received voltage commands to render a second common mode signal. The rendered first and second common mode signals have the same or similar waveform with opposite polarity with respect to one another.

A battery state estimating apparatus as an embodiment includes a state estimator, a power estimator, and a determiner. The state estimator estimates a state of a battery. The power estimator estimates first power amount charged/discharged by the battery within a charging/discharging period, based on the state. The determiner compares the first power amount with second power amount inputted/outputted to/from the battery within the charging/discharging period and thereby determines validity of the state.

A motor current controlling circuit having a voltage detection mechanism is provided. A first terminal of a first low-side transistor is connected to a second terminal of a first high-side transistor. A node between the first terminal of the first low-side transistor and the second terminal of the first high-side transistor is connected to a first terminal of a motor. A first terminal of a second low-side transistor is connected to a second terminal of a second high-side transistor. A zero current detector circuit detects a voltage of the node and determines whether or not a current flowing through the motor is equal to a zero value to output a zero current detected signal according to the detected voltage. A controller circuit controls a driver circuit to turn on or off the high-side transistors and the low-side transistors according to the zero current detected signal.

An electric work machine in one aspect of the present disclosure includes an output shaft, a brushless DC motor, a first positive-side conduction path, a first negative-side conduction path, a first switch device, a manual switch, a rotation sensor, and a controller. The first switch device is on the first positive-side conduction path or the first negative-side conduction path. The controller controls a magnitude of a conduction angle based on an actual rotational frequency and a target rotational frequency of the brushless DC motor.

A power tool includes a motor, an output shaft, a commutation detection device, and a controller. The commutation detection device is connected to the motor and used for obtaining commutation information of the motor. The controller is capable of outputting a control signal to control the motor to rotate. When the commutation information does not match a preset commutation condition, the control signal is adjusted based on the commutation information such that a rotational speed of the motor is maintained to be a target rotational speed.

A rotary impact tool includes an impact assembly, a brushless motor, a transmission assembly, a drive circuitry, and a controller. The controller is configured to acquire a commutation interval of the brushless motor, output a first control signal to the drive circuitry causing the brushless motor to operate at a preset initial speed, and output a second control signal to the drive circuitry to gradually increase a rotational speed of the brushless motor to a preset final speed, when a commutation interval of the brushless motor becomes greater than or equal to a preset time threshold, where the preset initial speed is less than the preset final speed.

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 single-phase brushless DC motor includes a rotor rotatable about a central axis, a stator including salient pole portions, a stator core including a slot between the salient pole portions, and a winding wound around the salient pole portions, the stator opposing the rotor with an air gap interposed therebetween, and a substrate fixed to the stator and including a driver to perform energization control of the winding. The driver includes a Hall element to acquire a timing of the energization control. The substrate includes a Hall IC to detect a circumferential position of the rotor separately from the driver.

An example apparatus as discussed herein includes a controller. The controller receives control input indicating how to control operation of a motor. In accordance with the control input, the controller controls a corresponding flow of current through each of multiple windings of the motor. According to one implementation, the controller balances positive demagnetization and negative demagnetization of each of the multiple windings in a respective control cycle.

An example apparatus as discussed herein includes a controller. The controller receives control input indicating how to control operation of a motor. In accordance with the control input, the controller controls a corresponding flow of current through each of multiple windings of the motor. According to one implementation, the controller balances positive demagnetization and negative demagnetization of each of the multiple windings in a respective control cycle.