A BLDC motor driver circuit includes: a driving power stage circuit configured to provide a start-up test signal in a start-up mode to excite a BLDC motor, to drive a rotor of the BLDC motor to rotate for a test; a current unidirectional circuit coupled to the BLDC motor at a reverse end for detecting a BEMF, to generate a detection signal at a forward end of the current unidirectional circuit, wherein when a voltage at the reverse end exceeds a voltage at the forward end, the current unidirectional circuit limits the voltage at the forward end not to be higher than a clamp voltage; a biasing circuit for biasing the current unidirectional circuit in a forward operation state and for providing the clamp voltage; and a sensor circuit for generating a sensing signal according to the detection signal to indicate a test rotation state of the BLDC motor.

A converter controller configured to control a firing phase of a converter includes an integral element integrating a deviation of DC current from a current command value and generates a voltage command value of output voltage of the converter by performing control calculation of the deviation. In a first mode of performing commutation of an inverter by intermittently setting DC current to zero, the converter controller sets DC current to zero for a predetermined pause time by narrowing a phase control angle simultaneously with a commutation command for the inverter. When the control calculation is resumed immediately after the pause time, the converter controller uses a control amount calculated in control calculation immediately before the pause time as a preset value of the integral element immediately after the pause time.

A control assembly for use in controlling a speed of operation of an electric device, the control assembly including: a control assembly housing; a magnetic sensor; a magnetic element; an actuator that is configured for movement relative to the control assembly housing wherein responsive to said movement of the actuator relative to the control assembly housing, the magnetic sensor and magnetic element move relative to each other between at least one of a first position and a second position such that the magnetic sensor senses a first magnetic field reading when in the first position and senses a second magnetic field reading when in the second position; and, a control module operably connected to the magnetic sensor and configured for controlling the electric device to operate in at least one of a first speed and a second speed by reference to an output of the magnetic sensor indicative of the sensed first magnetic field reading and the second magnetic field reading respectively.

When the rotation direction of a motor is determined by a connection determination unit not to match a rotation command, the phase sequence of a current detection signal and the phase sequence of a voltage command are changed by a phase sequence change unit, or the positive/reverse polarity of an encoding signal outputted from an encoder is inverted by the phase sequence change unit, whereby the rotation direction of the motor controlled by a motor control device can match the rotation command.

A method for determining the state of a brushless motor having first, second and third phases, in some embodiments, comprises: decoupling said motor from a power source; determining whether said motor is rotating or non-rotating; if the motor is rotating, determining a first phase voltage state relative to a common voltage and a second phase voltage state relative to the common voltage, said first phase and second phase voltage states determined when a third phase voltage is within a predetermined range of said common voltage; and if the first phase voltage state and the second phase voltage state are the same, repeating said determination as to whether the motor is rotating or non-rotating.

A method for determining the state of a brushless motor having first, second and third phases, in some embodiments, comprises: decoupling said motor from a power source; determining whether said motor is rotating or non-rotating; if the motor is rotating, determining a first phase voltage state relative to a common voltage and a second phase voltage state relative to the common voltage, said first phase and second phase voltage states determined when a third phase voltage is within a predetermined range of said common voltage; and if the first phase voltage state and the second phase voltage state are the same, repeating said determination as to whether the motor is rotating or non-rotating.

A short pitched switched reluctance motor control apparatus comprising a voltage provider comprising a first coupling and a second coupling configured to be coupled to a phase winding of the switched reluctance motor for applying a voltage to drive current in the winding between the first and second coupling is disclosed. The apparatus further comprises a controller configured to apply a first voltage pulse to the first coupling, and to apply a second voltage pulse to the second coupling, wherein the start of the second pulse is delayed with respect to the start of the first pulse, and the end of the first pulse is delayed with respect to the end of the second pulse.

A laser projection apparatus includes a laser light source, a diffusion wheel including a motor and a diffusion portion, a diffusion wheel driving circuit, a switch circuit and a main control circuit. The main control circuit is configured to sequentially output first and second startup PWM signals in response to a startup instruction. The diffusion wheel driving circuit is configured to drive the motor to drive the diffusion portion to rotate in response to the second startup PWM signal. The main control circuit is configured to obtain a rotation speed of the motor, and output an operating PWM signal and a first switch signal when the rotation speed reaching a target rotation speed is determined. The diffusion wheel driving circuit is configured to drive the motor to drive the diffusion portion to rotate in response to the operating PWM signal. The switch circuit is configured to provide a laser drive signal to the laser light source in response to the first switch signal, to drive the laser light source to emit laser beams.

The method is for making an electric motor more efficient by iteratively changing when a processor sends activation signals to transistors to minimize a current required to rotate a rotor at a constant rotational speed. The method is also for changing a rotational direction of the rotor by switching the order in which activation signals are sent to the transistors.

The method is for making an electric motor more efficient by iteratively changing when a processor sends activation signals to transistors to minimize a current required to rotate a rotor at a constant rotational speed. The method is also for changing a rotational direction of the rotor by switching the order in which activation signals are sent to the transistors.