Patent ID: 7525270

Claim:
A motor control apparatus that supplies a drive signal to a motor for driving a compressor that is joined to the motor and compresses a refrigerant used in a vehicle refrigeration cycle, the motor control apparatus for controlling the motor to reduce noise or vibration due to operation of the motor and comprising: a detecting means for detecting a rotational speed of the motor; a command signal processing means that generates a command signal for allowing the motor to rotate at a predetermined rotational speed; a drive means that generates the drive signal based on the command signal and supplies the drive signal to the motor, and a control signal generation means that generates a control signal for allowing the motor to produce a control torque having a frequency equal to one of frequencies of the noise and vibration, the frequency of the control torque having a plurality of frequency components including at least a resonance frequency of the motor, a resonance frequency of a motor mounting structure to which the motor is fixed, and a resonance frequency of the refrigerant, the control signal generation means outputting the control signal to the command signal processing means, wherein the control signal has an amplitude smaller than the amplitude of the command signal and includes a plurality of sinusoidal components each corresponding to a different one of the plurality frequency components of the control torque, the command signal processing means generates the command signal based on the control signal and outputs the command signal to the drive means, and the control signal generation means sets an amplitude and a phase angle of the control signal and the frequency based on the rotational speed of the motor, a rotational angle of the motor, or a physical quantity that is obtained from the load when the motor drives the load, and generates the control signal based on the amplitude, the phase angle, and the frequency.