| 摘要 |
A system for controlling the torque of a polyphase alternating current (AC) induction motor, including: a triggerable bi-directional electronic switch (50) for conducting an AC current, when the switch is triggered, to the AC induction motor (28); a pulse width modulated (PWM) signal generator (46) for generating a PWM signal; and zero cross circuitry (58, 60, 62) for detecting zero cross points of an AC power supply (44) which occur during pulses of the PWM signal, the zero cross circuitry generating an output pulse for triggering the bi-directional electronic switch at each detected zero cross point, wherein the duty cycle of the PWM signal is set to control the average torque of the AC induction motor. |
