| 摘要 |
PURPOSE:To control the rotation of an AC single-phase motor stably over a wide rotational speed range without causing fluctuation of rotation or lowering of torque. CONSTITUTION:A voltage doubler/rectifier circuit 21 provides DC positive and negative power supplies. A four-phase pulse modulated signal generating circuit 23 provides first to fourth switch circuits 41, 42, 51, 52 with four-phase PWM signals phi1-phi4 having sinusoidally modulated pulse width generated with timing shifted by a quarter of the modulation period. First coil L1 of a motor 1 is intermittently applied with positive and negative voltages synchronized with the PWM signals phi1, phi3 and a first short circuit switch 43 is turned ON during the interrupting interval. Similarly, second coil L2 is applied with positive and negative voltages synchronized with the PWM signals phi2, phi4 and a second short circuit switch 53 is turned ON during the interrupting interval. Consequently, the second coil L2 is fed with an AC current having phase shift of 90 deg. from the current flowing through the first coil L1. |
