| 摘要 |
PROBLEM TO BE SOLVED: To prevent a loss and damage of a power transistor and the like caused by heat generation therein, securing the stability of a control for the number of revolutions of a motor and for torque in a wide range. SOLUTION: A motor-control unit 15 carries a map designating the number of revolutions of the motor 11 and the relation between torque and a carrier frequency, and operates the carrier frequency by use of the number of revolutions of the motor read from a revolution-number sensor 16 and by use of a torque-command value input from a vehicle-control unit 17. When the number of revolutions is low and the torque is high, the carrier frequency is lowered in order to prevent heat generation in the power transistor 14 and the motor 11. At this time, the control is stabilized even if the carrier frequency is low, and in the meantime when the number of revolutions is high, the carrier frequency is raised for stabilizing the control. However, when the torque is high and even when the number of revolutions is not low, the carrier frequency shall be lowered for fear that the heat generation gets larger in the power transistor 14. |
