| 摘要 |
<P>PROBLEM TO BE SOLVED: To stably drive a brushless motor in both low speed drive and high speed drive of sensorless drive. <P>SOLUTION: A control section 3 includes an induced voltage detection circuit 4, a rotor position calculation circuit 5, a target rotational frequency calculation circuit 6, a speed control circuit 7, an adjustment section 11, a duty control circuit 8 and a commutation control circuit 9. The speed control circuit 7 calculates a target rotating speed and generates a speed control signal to rotate a rotor at the calculated target rotating speed. The adjustment section 11 generates adjustment signals to adjust a carrier frequency and a duty ratio of the carrier frequency on the basis of the target rotational frequency information. The duty control circuit 8 generates a duty control signal to control the duty ratio in accordance with the carrier frequency on the basis of the speed control signal and the adjustment signals. The commutation control circuit 9 generates a switching control signal to turn on/off a plurality of switching elements on the basis of the duty control signal. <P>COPYRIGHT: (C)2012,JPO&INPIT |
