JPH0588066B

PURPOSE:To reduce a switching loss by individually controlling the firing angles of inverters in response to the variation in the output current at a load side of a multiplex inverters, and operating by the frequency of 1/n (n is the number of units). CONSTITUTION:A controller of a multiplex inverter has a circuit I for forming and distributing firing and extinguishing pulses for forming and distributing firing pulses in a direction for decreasing or increasing a load current with respect to a voltage inverter when a deviation between a load current ic and a set value ic exceeds the upper or lower limit value, an interrupt circuit II for forming and distributing similar firing and extinguishing pulse to the second inverter when the control of only one inverter becomes insufficient, and an arm shortcircuit generation preventing circuit III. Thus, even if the number of operations as observed from the load side is (n), the number of the operations of the n inverters becomes once, and the operating frequency of each inverter can be reduced equivalently to 1/n of the load side.