SYSTEM FOR REALIZING ROTOR VARIABLE FREQUENCY SPEED CONTROL ASYNCHRONOUSLY AND SIMULTANEOUSLY BY DRIVING FOUR MOTORS VIA ONE INVERTER

摘要

The present invention discloses a system for realizing rotor variable frequency speed control asynchronously, which drives a plural of motors via one inverter. This system is consisted of a motor group, a rectifier group, a current limiter group, a chopper group, an isolator group, an active inverter, an A/D converter group, a signal processor group, a current detector group and a voltage detector group. By employing inversion control theory and CPU control technology, a plural of motors are controlled on line, the voltage output by one inverter is used as the additional inverse electromotive force of each motor, and each chopper is effectively turned on and turned off via a PWM signal which is output by each driver, so that four jobs of a crane, lifting, luffing, revolving and walking, can be realized. By the present invention, the circuit is simplified, the size is reduced, the cost is lowered, and the reliability is improved. When the crane rises, redundant electric energy will always be fed back to the motor via the same inverter, and when the crane falls, the motor will be in generator state, and the electric energy generated will be again fed back to the motor or the electric network via the same inverter, thereby realizing energy recovery and saving the energy source.