A method and system for operating a hybrid propulsion system, includes controllably providing a first power to a first bus and a first inverter, electrically coupling a first motor with a second inverter by way of a second bus, operably converting, by the second inverter, the first power received by the first inverter to a starting power adapted for starting the first motor, and increasing, by the second inverter, the starting power to match the first power received.

An electric tool includes a drive structure, a motor, a driver circuit, and a controller. The controller is configured to output a first control signal to control the motor to drive the drive structure to operate in a first operation mode for a preset period of time in response to receiving a start instruction. After the preset period of time, the controller will output a second control signal to control the motor to drive the drive structure to operate in a second operation mode to a preset state. The first operation mode and the second operation mode are two opposite operation modes.

An electric tool includes a drive structure, a motor, a driver circuit, and a controller. The controller is configured to output a first control signal to control the motor to drive the drive structure to operate in a first operation mode for a preset period of time in response to receiving a start instruction. After the preset period of time, the controller will output a second control signal to control the motor to drive the drive structure to operate in a second operation mode to a preset state. The first operation mode and the second operation mode are two opposite operation modes.

A motor control system includes a reference current generator that generates a reference current based on a command, a motor voltage providing device that generates a phase voltage based on the reference current, a high frequency voltage, and a feedback current and provides a motor with the phase voltage, and a high frequency voltage generator that generates the high frequency voltage corresponding to a magnitude of voltage generated based on the reference current and the feedback current.

An air conditioning system includes a compressor including a motor, a condenser, and an evaporator; a drive including an inverter providing a multiphase, AC output voltage to the motor; a current sensor configured to sense an output current generated by the inverter; a controller configured to communicate with the current sensor and the inverter, the controller configured to provide a voltage command to the inverter, the controller configured to execute operations including: monitor the output current generated by the inverter; compare the output current to a threshold; determine the occurrence of an over current condition when the output current exceeds the threshold; when an over current condition is detected, reducing the voltage command to the inverter.

A method for starting a synchronous motor is provided. The synchronous motor includes a rotor for creating a first magnetic field and a stator with stator windings connected to an electrical energy converter for converting a supply voltage into a stator voltage to be applied to the stator windings to create a rotating second magnetic field interacting with the first magnetic field. The method includes applying reference stator voltages to the stator windings, where the reference stator voltages are determined from a reference current vector and a reference rotor speed, measuring stator currents, calculating an estimated rotor speed and rotor position from the applied stator voltages and the measured stator currents, calculating a speed error by subtracting the estimated rotor speed from the reference rotor speed, determining a reference torque producing current component from the speed error, and modifying the reference current vector with the reference torque producing current component.

An apparatus according to the aspect of the embodiments includes a phase determiner configured to determine a rotational phase of a rotor, a speed determiner configured to determine a rotational speed of the rotor, a controller having a first control mode for controlling the motor by supplying constant currents to windings, and a discriminator configured to discriminate whether a rotation of the motor is abnormal based on the rotational speed when the rotational speed corresponding to a command speed is equal to or higher than a predetermined value in a state where the controller is controlling the motor in the first control mode. When a signal output from the discriminator indicates that the rotation of the motor is abnormal, the controller stops the motor. When the signal output from the discriminator indicates that the rotation is not abnormal, the controller continues a drive of the motor.

An apparatus according to the aspect of the embodiments includes a phase determiner configured to determine a rotational phase of a rotor, a speed determiner configured to determine a rotational speed of the rotor, a controller having a first control mode for controlling the motor by supplying constant currents to windings, and a discriminator configured to discriminate whether a rotation of the motor is abnormal based on the rotational speed when the rotational speed corresponding to a command speed is equal to or higher than a predetermined value in a state where the controller is controlling the motor in the first control mode. When a signal output from the discriminator indicates that the rotation of the motor is abnormal, the controller stops the motor. When the signal output from the discriminator indicates that the rotation is not abnormal, the controller continues a drive of the motor.

A method of controlling a brushless permanent magnet motor includes measuring a mains power supply voltage of the motor. The method includes determining whether the mains power supply voltage lies within a first range representative of a first country's mains power supply or a second range representative of a second country's mains power supply. The method includes advancing commutation of a winding of the motor relative to a zero-crossing of back EMF in the winding where the mains power supply voltage lies within the first range, and retarding commutation of the winding relative to a zero-crossing of back EMF in the winding where the mains power supply voltage lies within the second range.

A soft-start circuit which can be applied to a motor controller is provided. The soft-start circuit comprises a controller, a counting unit, a digital-to-analog converter, a current detecting unit, and a comparator. The soft-start circuit uses a plurality of current limit values so as to achieve a maximum output power and prevent damage to a motor coil.