A method for balancing thermal stresses in semiconductor switching devices may include (a) monitoring temperatures of the semiconductor switching devices to provide a temperature difference between two of the switching devices; and (b) based on the temperature difference, providing a zero-sequence component to be used for adjusting conduction times of each of the semiconductor devices.

A vehicle door checker integrated with a power drive unit for an automobile door includes a direct current permanent magnet electric motor subject to cogging torque. The electric motor includes a central shaft. The vehicle door checker also includes a cogging torque increase device that is mounted to the central shaft externally of the motor. The cogging torque increase device includes pairs of oppositely magnetized permanent magnets that are mounted coaxially in a stator and rotor respectively about the motor shaft. The stator magnets and the rotor magnets shift into and out of alignment with each other as the shaft is rotated such that the motor is held in multiple discrete stable positions that correspond to check positions of an automobile door.

A linear resonant device and a braking method for the same. The linear resonant device comprises a linear resonant motor and a drive chip. The drive chip pre-stores a drive waveform and at least one first braking waveform therein. The method comprises: determining, in response to a braking instruction, whether vibration of the linear resonant motor meets a first condition while being driven by the drive waveform; and if so, controlling the drive chip to drive, by using the first braking waveform, the linear resonant motor and to conduct a first braking process for the linear resonant motor, wherein the first braking waveform comprises at least two pulse waveforms, and an amplitude value of each of the at least two pulse waveforms gradually decreases along a propagation direction of the first braking waveform.

A linear resonant device and a braking method for the same. The linear resonant device comprises a linear resonant motor and a drive chip. The drive chip pre-stores a drive waveform and at least one first braking waveform therein. The method comprises: determining, in response to a braking instruction, whether vibration of the linear resonant motor meets a first condition while being driven by the drive waveform; and if so, controlling the drive chip to drive, by using the first braking waveform, the linear resonant motor and to conduct a first braking process for the linear resonant motor, wherein the first braking waveform comprises at least two pulse waveforms, and an amplitude value of each of the at least two pulse waveforms gradually decreases along a propagation direction of the first braking waveform.

The electric-powered actuator includes a control device including: a motor angle estimation unit, and a reverse-input holding control section having a function of engaging an engaging part with an engaged part by controlling a solenoid to set the reverse-input holding mechanism into a reverse-input holding state while the electric-powered actuator is applying a load and a function of, from the reverse-input holding state, disengaging the engaging part from the engaged part to set the reverse-input holding mechanism into a reverse-input holding release state. The reverse-input holding control section includes an engagement intermediate control function section configured to control the estimated rotation angle such that the engaged part and the engaging part come into a predetermined positional relation within a certain period of time, when the engaging part is brought into engagement with the engaged part and when the engaging part is brought out of engagement with the engaged part.

The invention relates to fluid drive systems used in fluid wells and brake systems for permanent magnet wellhead direct drives. The braking controller connects or disconnects a brake resistor from a back EMF. A variable frequency drive (VFD) drives the motor and communicates with the control circuitry of the brake controller. The control circuitry monitors the brake resistor and depending on the rotational speed and direction of the motor and operating state of the VFD, disconnects or connects the brake resistor. If the direction of the motor is in reverse and above a threshold speed, it connects the brake resistor. If the direction of the motor is in reverse and below the threshold speed, the control circuitry dissipates stored back EMF through the brake controller. The amount of stored back EMF corresponds to the time to empty a pump.

The invention relates to fluid drive systems used in fluid wells and brake systems for permanent magnet wellhead direct drives. The braking controller connects or disconnects a brake resistor from a back EMF. A variable frequency drive (VFD) drives the motor and communicates with the control circuitry of the brake controller. The control circuitry monitors the brake resistor and depending on the rotational speed and direction of the motor and operating state of the VFD, disconnects or connects the brake resistor. If the direction of the motor is in reverse and above a threshold speed, it connects the brake resistor. If the direction of the motor is in reverse and below the threshold speed, the control circuitry dissipates stored back EMF through the brake controller. The amount of stored back EMF corresponds to the time to empty a pump.

A safety switching system and method for braking an electric motor in a mobile device. A multi-phase shorting system brakes the motor by diverting power from the motor windings. Multiple independent switching units each include a switch control unit controlling multiple normally-closed switches which, in response to a safety controller, close to connect a respective motor winding to electrical ground. An electromechanical brake system mechanically brakes the motor. An independent switching unit includes two normally-open switches which, in response to the safety controller, opens to activate an electromechanical brake. A feedback system communicates to the safety controller a switch failure of any of the switches either as a short circuit fault or an open circuit fault. The feedback system may include an analog and/or a digital feedback system. If a switch failure is detected, the safety controller may activate the multi-phase shorting system and the electromechanical brake system.

An example system includes a first surge protection module configured to receive a command signal; a motor control module configured to receive: (i) the command signal from the first surge protection module, and (ii) an enable signal, wherein the motor control module provides a control signal in response to the enable signal meeting a threshold value; a motor configured to receive the control signal from the motor control module; a switch coupled to the motor and configured to be triggered based on a state of the motor, wherein the switch comprises: (i) a first terminal configured to provide an indication signal of the state of the motor and provide the enable signal to the motor control module, and (ii) a second terminal connected to ground; and a second surge protection module coupled to the first terminal of the switch.

An apparatus and method for rotating a part includes a sequence of relays to rotate the part given number of degrees. The apparatus does not require software or complex mechanical gearing.