Electric motor control device, compressor, and electric motor control method

A compressor, comprising:

• an electric motor control apparatus;
• and
• an electric motor to be controlled by the electric motor control apparatus;
• wherein the electric motor control apparatus comprises:
• a speed ripple component extraction unit configured to extract a speed ripple component from a difference between an angular frequency command and an angular frequency feedback;
• a phase locked loop circuit configured to generate a phase of the speed ripple component from the speed ripple component;
• a torque compensation value generation unit configured to multiply a value of a periodic function corresponding to the phase and a given amplitude by each other, to thereby generate a torque compensation value;
• a speed control unit configured to calculate a torque command value from the difference between the angular frequency command and the angular frequency feedback;
• and
• a current control unit configured to control a current to be output to an electric motor based on a compensated torque command obtained by adding the torque compensation value to the torque command value.

An electric motor control method, comprising:

• extracting a speed ripple component from a difference between an angular frequency command and an angular frequency feedback;
• generating a phase of the speed ripple component from the speed ripple component;
• multiplying a value of a periodic function corresponding to the phase and a given amplitude by each other, to thereby generate a torque compensation value;
• calculating a torque command value from the difference between the angular frequency command and the angular frequency feedback;
• obtaining a compensated torque command by adding the torque compensation value to the torque command value;
• and
• controlling a current to be output to an electric motor based on the compensated torque command.