Patent ID: 7199540

Claim:
A motor drive apparatus comprising: a first drive circuit driving a first motor; and a drive circuit control circuit controlling said first drive circuit so that said first motor outputs a torque according to a requested torque, wherein said drive circuit control circuit includes control mode switching means for switching control mode of said first motor between PWM control mode, overmodulation control mode and rectangular-wave control mode, according to a modulation factor of said first drive circuit, and oscillation-reducing control means for generating, when the control mode of said first motor is said PWM control mode, an oscillation-reducing torque for reducing oscillations of the torque that is output from said first motor and adding said oscillation-reducing torque to said requested torque to provide the resultant sum as a new requested torque, said control mode switching means switches the control mode of said first motor from said PWM control mode to said overmodulation control mode in response to the fact that the modulation factor of said first drive circuit exceeds a first predetermined value, and said oscillation-reducing control means gradually decreases said oscillation-reducing torque in a period in which the modulation factor of said first drive circuit changes from a second predetermined value that is smaller than said first predetermined value to reach said first predetermined value.