| 摘要 |
PROBLEM TO BE SOLVED: To suppress distortion in drive current flowing to a drive coil and maintain noise, vibration and rotation irregularity small even when the level of a drive and control signal for varying forguce is large when a motor is driven and controlled in PWM. SOLUTION: A drive waveform generation circuit 1 generates a drive waveform signal based on the U-phase, V-phase and W-phase drive currents flowing to drive coils La-Lc, and variably outputs the waveform in response to a drive control signal level Vc. A PWM conversion circuit 3 converts into the PWM drive signal of pulse width in response to the drive waveform signal level. A drive circuit 5 switches and energizes a three-phase drive current based on the PWM drive signal to the drive coils La-Lc. A limiter circuit 9 fixes it to a limit level to be output to the drive waveform generation circuit 1 when the drive control signal level exceeds the limit level corresponding to the duty 100% of the PWM drive signal. |
