Method and system for controlling electric motor, and controller

A system for controlling a motor, comprising a first determination module, a second determination module, and a control module;

• wherein
• the first determination module is configured to determine whether a rotational speed of the motor reaches a preset rotational speed when a motor operates in an open-loop manner, and to send a first control instruction to the second determination module in a case that the rotational speed of the motor reaches the preset rotational speed;
• the second determination module is configured to determine whether an absolute value of an angle difference between an open-loop angle and a calculated position angle of the motor is greater than a preset angle in response to a reception of the first control instruction, and to send a second control instruction to the control module in a case that the absolute value of the angle difference is less than or equal to the preset angle;
• and
• the control module is configured to control the motor to operate in the open-loop manner, and to control the motor to operate in a closed-loop manner in response to a reception of the second control instruction.

A controller, comprising a system for controlling a motor, wherein the system comprises a first determination module, a second determination module, and a control module;

• and wherein:
• the first determination module is configured to determine whether a rotational speed of the motor reaches a preset rotational speed when a motor operates in an open-loop manner, and to send a first control instruction to the second determination module in a case that the rotational speed of the motor reaches the preset rotational speed;
• the second determination module is configured to determine whether an absolute value of an angle difference between an open-loop angle and a calculated position angle of the motor is greater than a preset angle in response to a reception of the first control instruction, and to send a second control instruction to the control module in a case that the absolute value of the angle difference is less than or equal to the preset angle;
• and
• the control module is configured to control the motor to operate in the open-loop manner, and to control the motor to operate in a closed-loop manner in response to a reception of the second control instruction.