SPEED CONTROLLER WITH SECONDARY CHOPPER OF WINDING TYPE INDUCTION MOTOR

摘要

PURPOSE:To suppress overvoltage due to the overcharging of a commutating capacitor and prevent the commutation failure of an inverter from being generated, by stopping the charging of the commutating capacitor, when capacitor voltage is set to be the set overvoltage or higher. CONSTITUTION:The voltage of a commutating capacitor 6 is detected by a voltage detector 25. When the voltage comes to the overvoltage setting value of an overvoltage setting unit 26B or higher, then a secondary chopper 4 is turned on, and the charging of the commutating capacitor 6 is stopped. At the same time, power stored in the commutating capacitor 6 is regenerated to an AC power source 1 by an inverter unit 8, and so voltage is lowered. Accordingly, when the commutating capacitor 6 is overcharged and overvoltage is applied to the inverter unit 8, then operation stopping due to commutation failure is not performed.