A SYSTEM FOR DRIVING ASYNCHRONOUSLY MULTIPLE MOTORS BY ONE INVERTER AND FOR REALIZING FREQUENCY VARIATION AND SPEED ADJUSTING OF ROTORS

摘要

The present invention discloses a system for realizing rotor variable frequency speed control asynchronously and simultaneously by driving multiple motors via one inverter, which consists of a motor group, a rectifier group, a chopper group, an isolator group, an amperite group, a power capacitor group, a full bridge or a half bridge, a speed feedback voltage detector group and a current feedback voltage detector group. By employing inversion control theory, the voltage outputs by a full-bridge inverter or a half-bridge inverter is taken as an additional inverse electromotive force of each functional motor according to the rated power of the motor, and each motor is made to operate asynchronously and simultaneously by the work of each chopper, thereby the operations of a crane, lifting, luffing, revolving and walking, can be realized. During the rising of the crane, redundant electric energy will always be fed back to the motor via an inverter; and during the falling of the crane, the motor will be in electricity generating state, and the electric energy generated will be fed back to the motor via the inverter, thus energy recovery may be realized. The invention has such characteristics as simple circuit, small size, low cost, high reliability and energy saving.