| 摘要 |
PURPOSE:To improve an efficiency of a motor, to improve a power factor, to reduce harmonic waves and noise by forming a suitable motor current waveform. CONSTITUTION:A pulse width modulation waveform combining circuit for generating a drive signal of a switching element has memory means 17 for storing a reference pulse waveform data train, phase control means 12 for controlling starting phase of the train, and offset control means 13, 18 for controlling an offset of a reference level for uniformly varying a duty ratio of the train controlled in its starting phase. |
