Abstract: Disclosed is a controller which controls the a.c. (alternating current) on the basis of pulse-width modulation (PWM) for a multiple inverter which transforms d.c. power into high-voltage, high-capacity a.c. power with variable voltage and/or variable frequency. Several 3-phase inverter circuits connected through a transformer are used to form a polyphase mulitple inverter which produces the output voltage and current with synthesized voltage and current waveforms. The PWM controller produces multiple pulse trains within a half cycle of the a.c. output waveform and varies the equivalent voltage of pulses in a sinusoidal waveform, thereby obtaining a smooth output voltage and current waveforms. A plurality of 3-phase inverter main circuits connected to the d.c.

Abstract: A PWM control apparatus for an interphase reactor multiplex inverter in which the load current in each phase output from the midpoint of each of the interphase reactors is quickly controlled by feedback control with a signal corresponding to the sum of the output currents of the inverters in the same phase, the voltage command value for each phase of each inverter is corrected with a signal corresponding to the difference between output currents of the inverters in the same phase (proportional to the circulating current), whereby the interphase voltage difference developed across the interphase reactor in each phase is quickly controlled and the circulating current in each phase is controlled to become extremely small.