| 摘要 |
PURPOSE:To reduce noise by setting a switching frequency of switching means of a plurality of motors to the same and providing a difference of a predetermined value between phases of one and the other switching means. CONSTITUTION:Carrier waves to be applied to comparators 5, 6 as control means have the same frequency and different phases of a deviation of a predetermined value. Accordingly, PWM signals to be output from the comparators 5, 6 having the same frequency and a deviation of a predetermined value of different phases, and switching phases of inverters 7, 8 as switching means are also deviated by a predetermined value. Thus, phases of switching noises generated from a first motor 11 and a second motor 12 are also deviated by a predetermined value, and noises are cancelled by the phase difference. Thus, the switching noises can be effectively reduced. |
