| 摘要 |
A system for driving induction motors which controls properly the speed of the induction motor in a high-speed rotation region and is excellent in the response to a speed command. Slip pulse data (SB) and phase shift pulse data (FB), which are calculated by a processor (1) according to the speed command and the output of a speed sensor, are created. According to these data, slip pulses (SSP) and phase shift pulses (FSP) are outputted from a circuit (20) for generating slip pulses and from a circuit (21) for generating phase shift pulses respectively. A counter (24) counts the feedback pulses calculated according to the output of the speed sensor and the pulses fed from a circuit (23) for superimposing pulses, which correspond to the result of adding the slip pulses and feedback pulses calculated according to the output of the speed sensor to the phase shift pulses. The counter (24) generates a first changing over signal (CS1) whenever the counter (24) counts the predetermined number of the pulses. A circuit (26) for outputting square waves generates square wave signals (Us-Ws) according to a first changing over signal (CS1), a second changing over signal (CS2) obtained by delaying the signal (CS1), and signals (RS, RS) for discriminating between rotation directions which are fed from the circuit (23). The motor is driven and controlled by the square wave signals while being driven at a high-speed, or by PMW signals (Up-Wp) generated by the processor instead of the square wave signals while being driven at a low-speed. <IMAGE> |
