| 摘要 |
PURPOSE:To prevent abnormal vibration or abnormal noises due to a resonance phenomenon of mechanical system by setting the frequency of reference input signals in pulse width modulation control to value parting from the resonance frequency of the mechanical system or the frequency of integer times as large as the frequency. CONSTITUTION:In a reference input signal generating circuit 77, the frequency of the reference input signals can be selected from two kinds or more of value previously determined. Accordinly, the generation of the resonance phenomenon in the mechanical system can be prevented by changing over the frequency of the reference input signals to the second setting different from the first setting when the resonance frequency of the mechanical system connected to an output shaft of the motor or the frequency of iteger times oa large as the frequency is close to the reference frequency. |
