A SYSTEM FOR REALIZING SIMULTANEOUSLY FREQUENCY VARIATION AND SPEED ADJUSTING OF ROTORS AND MAKING ONE INVERTER DRIVE ASYNCHRONOUSLY FOUR MOTORS

摘要

A system for realizing simultaneously frequency variation and speed adjusting of rotors and making one inverter (6) drive asynchronously four motors is composed of a motor unit (1), a rectifier unit (2), a current limiter unit (3), a chopper unit (4), an isolator unit (5), an active inverter (6), an A/D converter unit (9), a signal processor unit (10), a current detector unit (11), and a voltage detector unit (12). The four motors are controlled on line with an inverter control theory and a CPU control technique, the voltage outputted from the inverter (6) is used as the additional reverse electromotive force of each motor, and each chopper is turned on and turned off effectively with PWM signals outputted from each driver, thereby four operations are carried out including hoisting, amplitude variation, slewing, and movement in a crane.