A control method of a motor rotation speed may include calculating a q-axis potential difference of a synchronous coordinate system for controlling a q-axis current of the synchronous coordinate system based on a target rotation speed of a motor and a measured rotation speed value of the speed sensor, calculating a voltage command of the synchronous coordinate system based on the calculated q-axis potential difference of the synchronous coordinate system, and controlling an inverter connected to the motor according to the calculated voltage command of the synchronous coordinate system.

A control method of a motor rotation speed may include calculating a q-axis potential difference of a synchronous coordinate system for controlling a q-axis current of the synchronous coordinate system based on a target rotation speed of a motor and a measured rotation speed value of the speed sensor, calculating a voltage command of the synchronous coordinate system based on the calculated q-axis potential difference of the synchronous coordinate system, and controlling an inverter connected to the motor according to the calculated voltage command of the synchronous coordinate system.

An electric motor is disclosed that includes a stator winding defining a plurality of poles, with the winding being controllable to switch between a first number of poles and a second number of poles. A rotor rotatable within the stator includes a first group of magnetic flux barriers being without permanent magnet material and a second group of magnetic flux barriers at least partially filled with a permanent magnet material. A method of operating a line-start electric motor is also disclosed.

A motor detection method includes the following steps. An excitation current command is provided to a motor device, and the motor device is driven to rotate at the first angle. The first feedback angle of the motor device in the first resting position is detected and obtained. The motor device is driven to rotate at the second angle according to the excitation current command. The second feedback angle of the motor device in the second resting position is detected and obtained. The magnetic pole offset angle of the motor device is calculated according to the first feedback angle and the second feedback angle.

A motor detection method includes the following steps. An excitation current command is provided to a motor device, and the motor device is driven to rotate at the first angle. The first feedback angle of the motor device in the first resting position is detected and obtained. The motor device is driven to rotate at the second angle according to the excitation current command. The second feedback angle of the motor device in the second resting position is detected and obtained. The magnetic pole offset angle of the motor device is calculated according to the first feedback angle and the second feedback angle.

A motor drive device includes a motor having a rotor, and a control device that controls the motor. The control device calculates a first value based on a d axis current and a q axis current of the motor. The control device calculates a second value by integrating the first value. The control device calculates a third value by performing prescribed control for making the second value equal to zero. The control device performs, based on the third value, position control for causing a rotational position of the rotor to match a designated position.

A motor drive device includes a motor having a rotor, and a control device that controls the motor. The control device calculates a first value based on a d axis current and a q axis current of the motor. The control device calculates a second value by integrating the first value. The control device calculates a third value by performing prescribed control for making the second value equal to zero. The control device performs, based on the third value, position control for causing a rotational position of the rotor to match a designated position.