| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for driving a brushless DC motor which can switch a carrier frequency used for switching an inverter even when a rotational speed is not changed but a duty ratio, etc. is changed. <P>SOLUTION: The method for driving the brushless DC motor can switch the carrier frequency when load torque is reduced so that a duty ratio for regulating a duty ratio regulator 8 is reduced when a method for switching the carrier frequency is set in response to the duty ratio for deciding by a duty ratio deciding unit 7. Thus, the carrier frequency can be reduced before it is brought into a state that the on-width of a PWM pulse can be held only for a shorter time than a ringing noise width. As a result, erroneous detection due to ringing noise can be prevented, and pole position detecting accuracy can be improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
