A power conversion apparatus includes a first inverter, a second inverter, a drive circuit to provide control signals turning on low-side switch elements in the first inverter to the low-side switch elements when a failure has occurred on a first inverter side, and provide control signals to turn on low-side switch elements in the second inverter to the low-side switch elements when a failure has occurred on a second inverter side, and a control circuit. When a failure has occurred on the second inverter side, a first power supply voltage generated on the first inverter side is supplied to the drive circuit, while when a failure has occurred on the first inverter side, a second power supply voltage generated on the second inverter side is supplied to the drive circuit.

A system and a method detects blockage of an actuating assembly in a drug delivery device with a brushless DC or stepper motor. The Back EMF voltage is periodically measured at the driving contacts of the motor. A blockage indication value is periodically calculated based on the divergence of voltages measured at different driving contacts, and an alarming and/or mitigation action is initiated if the blockage indication value meets a predefined criterion such as exceeding a minimum or maximum value.

A back electromotive force sensing circuit can include: a sampling circuit configured to acquire a sampling signal representing a phase current of one of three phases of a three-phase permanent magnet motor, where the three-phase permanent magnet motor adopts sine wave control; and a signal processing circuit configured to receive the sampling signal, and to obtain a back electromotive force of the one phase according to a difference between a phase voltage of the one phase and a sum of a voltage across a phase resistor and a voltage across a phase inductor of the one phase.

A motor controller comprises a switch circuit, a driving circuit, and a pulse width modulation circuit. The switch circuit is coupled to a three-phase motor for driving the three-phase motor. The driving circuit generates a plurality of control signals to control the switch circuit. When the three-phase motor is operated in a start state, the motor controller may enable an electric period to be divided into more floating phase time intervals for switching phases, so as to increase the success rate of phase switching. When the three-phase motor is operated in a stable state, the motor controller may enable the electric period to be divided into less floating phase time intervals for switching phases, so as to reduce the noise and vibration of the three-phase motor.

An alternating current power tool includes a brushless motor, a power module, a voltage conversion module, a drive circuit, and a controller. The power module is configured to receive an alternating current to supply power to the stator winding. The voltage conversion module is configured to receive the alternating current received by the power module and operatively output a direct current bus voltage. The drive circuit is electrically connected to the voltage conversion module and configured to drive the brushless motor. The controller is configured to start timing when the alternating current received by the power module crosses through a point of zero. In a preset time interval [T1, T2] of each half cycle, a first control signal is outputted to the drive circuit to power on the stator winding.

A brushless DC electric (BLDC) motor driver circuit includes: a power stage circuit configured to operably drive a brushless DC electric (BLDC) motor according to a pulse width modulation (PWM) signal; and an abnormality diagnosis circuit, wherein when a first parameter is under control, the abnormality diagnosis circuit is configured to operably determine a rotation abnormality condition of the BLDC motor according to a second parameter; wherein the first parameter and the second parameter are correlated with the rotation of the BLDC motor.

A method for braking a single coil BLDC motor includes iterating a plurality of times through a sequence of: a braking state which lasts a braking period; and a high impedance state which lasts a cool down period. The current runs through the single coil during the braking state and no current runs through the single coil during the high impedance state. The transiting from the braking state to the high impedance state is done when the motor operates in generator mode.

A three-phase brushless motor control device uses one shunt resistor disposed on a bus of an inverter as a drive circuit driving a three-phase brushless motor and acquires a two-phase current of the three-phase brushless motor at a predetermined timing to vector-control the three-phase brushless motor. At this time, in accordance with a duration in which the two-phase current cannot be accurately acquired, the control device varies an acquisition timing of the two-phase current or varies a period during which the three-phase brushless motor is vector-controlled.

Fan controller (1) for a modular power supply having a fan (13). An output (8) is provided for transmitting control signals to the fan (13) for controlling fan speed. A plurality of sensor modules (20) are associated with a respective module (11,6,7) of the modular power supply. Each sensor module (20) includes a temperature detecting circuit comprising a sensor for sensing temperature variations in the respective module (11,6,7), a fan control circuit (30) galvanically isolated from the temperature detecting circuit for outputting a control signal to the output (8) for controlling the fan (13), and an optocoupler (10,9) for transferring an output signal from the temperature detecting circuit (20) to the fan control circuit (30) for generating the control signal.

A control circuit of a motor control device estimates an initial magnetic pole position of a rotor using an inductive sensing scheme. When estimating the initial magnetic pole position, a drive circuit applies a voltage to a stator winding at each of L electrical angles (L≥5) while changing the L electrical angles. An absolute value of an electrical angle difference of the voltage applied to the stator winding between an i-th time (2≤i≤L) and an i−1st time is 180−360/L degrees or more and 180+360/L degrees or less. An absolute value of an electrical angle difference of the voltage applied to the stator winding between a 1st time for initial position estimation and a last time before starting initial position estimation is 180−360/L degrees or more and 180+360/L degrees or less.