Patent ID: 8040081

Claim:
A motor drive apparatus, comprising: a plurality of multiphase AC motors coupled to be capable of outputting motive power to a common output shaft; a plurality of power converting devices connected to said plurality of multiphase AC motors, respectively; and a controller for controlling said plurality of power converting devices, each of said plurality of power converting devices including a plurality of arm circuits connected to respective phase coils of said multiphase AC motor, each of said plurality of arm circuits having first and second switching elements connected in series between first and second power supply lines with a connection point to said each phase coil interposed, and said controller including an abnormality control means, when a first power converting device among said plurality of power converting devices is abnormal, for instructing an abnormal state operation using a second multiphase AC motor different from a first multiphase AC motor connected to said first power converting device, a short circuit detecting means for detecting a short-circuited switching element based on a current flowing through said first power converting device as a result of operation of said second multiphase AC motor, in said abnormal state operation, a first motor control means for controlling the current flowing through said first power converting device by bringing into conduction a switching element connected in series to said short-circuited switching element with said connection point interposed, in said abnormal state operation, a second motor control means for controlling the current flowing through said first power converting device by bringing into conduction all of switching elements connected in parallel to said short-circuited switching element in the power supply line, in said abnormal state operation, and a selecting means for selectively setting said first motor control means and said second motor control means in accordance with a rotation speed of said first multiphase AC motor.