| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent an operator from being uncomfortable and to prevent wear of various sliding components from being accelerated surely by reducing mechanical vibration being transmitted into a car through a chassis. <P>SOLUTION: In PWM control for controlling a current flowing through a fan motor 13 driving a fan by turning a semiconductor switch element 12 on/off, a PWM pulse obtained by adding a vibration reducing pulse to a main PWM pulse is output from a gate signal generation circuit 10 within one period. Consequently, the rising time and the falling time of motor current are extended and torque variation of the fan motor 13 is made gentle, and a bracket fixed to the fan motor 13 is not twisted greatly at once but twisted gradually thus reducing mechanical vibration of the bracket. <P>COPYRIGHT: (C)2008,JPO&INPIT |
