VOLTAGE COMPENSATING CIRCUIT OF 3-PHASE INVERTER HAVING FOUR SWITCHES AND METHOD FOR COMPENSATING VOLTAGE

摘要

PROBLEM TO BE SOLVED: To provide a voltage compensating circuit of a 3-phase inverter having four switches capable of compensating a distortion of 3-phase applied voltages due to a voltage ripple and a method for compensating a voltage. SOLUTION: The voltage compensating circuit of the 3-phase inverter having four switches comprises upper and lower end DC link capacitors (C1, C2) connected in series to be charged by a DC voltage to be input, a B4 inverter (2) for supplying voltages charged in the capacitors (C1, C2) to a 3-phase motor by utilizing the four switches, a rectifying means for rectifying an AC power to be input of an AC power source into a DC voltage and then supplying the DC voltage to the capacitors (C1, C2), and a triac (T) connected at its input terminal to one terminal of the AC power source and connected at its output terminal to an intermediate point of the capacitors (C1, C2) to control charging states of the capacitors (C1, C2). In this circuit, a DC link voltage is controlled so that the capacitors (C1, C2) are charged via different routes.