Synchronous motor control method and device

A method for controlling synchronous motor is a method which detects a rotational position of a rotor using higher harmonics of input terminal voltages, higher harmonics of currents of a synchronous motor (4) driving a load having periodic torque variation and inductance distribution of the synchronous motor (4), which controls output currents or output voltages of an inverter (3) based upon the rotational position detection result so that speed variation of the synchronous motor (4) due to the periodic torque variation is denied, and which supplies the output voltages or output currents of the inverter (3) to the synchronous motor (4).

A method for controlling synchronous motor is a method which controls a synchronous motor (4) under a condition where speed command value, torque command or load changes from moment to moment,

• which calculates a rotational position of a rotor using input terminal voltages, currents of a synchronous motor (4) and instrumental constants of the synchronous motor (4),
• which controls output currents or output voltages of an inverter (3) based upon the rotational position calculation result, and
• which supplies the output voltages or output currents of the inverter (3) to the synchronous motor (4).

An apparatus for controlling synchronous motor comprising:

• rotational position detection means (6)(6′) for detecting a rotational position of a rotor using input terminal voltages, currents of a synchronous motor (4) driving a load having periodic torque variation and instrumental constants of the synchronous motor (4);
• and
• inverter controlling means (7b)(7c)(8)(9)(11) for controlling output currents or output voltages of an inverter (3) based upon the rotational position detection result so that speed variation of the synchronous motor (4) due to the periodic torque variation is denied.

An apparatus for controlling synchronous motor comprising:

• rotational position detection means (6)(6′) for detecting a rotational position of a rotor using higher harmonics of input terminal voltages, higher harmonics of currents of a synchronous motor (4) driving a load having periodic torque variation and inductance distribution of the synchronous motor (4);
• and
• inverter controlling means (7b)(7c)(8)(9)(11) for controlling output currents or output voltages of an inverter (3) based upon the rotational position detection result so that speed variation of the synchronous motor (4) due to the periodic torque variation is denied.

An apparatus for controlling synchronous motor is an apparatus which controls a synchronous motor (4) under a condition where speed command value, torque command or load changes from moment to moment, the apparatus comprising:

• rotational position calculation means (6)(6′) for calculating a rotational position of a rotor using input terminal voltages, currents of a synchronous motor (4) and instrumental constants of the synchronous motor;
• and
• inverter controlling means (7b)(8)(9) for controlling output currents or output voltages of an inverter based upon the rotational position calculation result.

An apparatus for controlling synchronous motor as set forth in one of claim 30 through claim 32, wherein the synchronous motor (4) is a motor having magnetic salient pole, and the rotational position calculation means (6)(6′) calculates a rotational position using higher harmonics of input voltage and higher harmonics of current.

• An apparatus for controlling synchronous motor as set forth in one of claim 30 through claim 33, wherein the synchronous motor (4) drives a compressor for an air conditioner.