| 摘要 |
<p>PURPOSE:To always operate a motor in the maximum efficiency state by driving the motor in accordance with a quasi-sinusoidal wave formed based on a power factor and a rotating speed. CONSTITUTION:When a pulse is applied from the terminal S1 of a controlling circuit 8 which receives signals from a rotating speed detector 11 and a power factor detector 10 to switching means 6, the switching means 6 will produce a DC power voltage +V having the same pulse interval and the same pulse width as the pulse from the terminal S1. When a pulse is then produced from a terminal S2, a DC power voltage -V having the same pulse interval and the same pulse width as the terminal S2 is produced from the output of switching means 7. The pulse outputs of these DC power voltages +V and -V are smoothed to a quasi-sinusoidal wave via a smoothing circuit formed of a coil L and a capacitor C. In this manner, the frequency can be varied by varying the pulse interval, and the effective voltage value can also be varied.</p> |
