Circuit for controlling output current balance between parallel driven PWM-type power inverting units

摘要

A circuit and method for controlling an output current balance for parallel driven PWM-type digitalized power inverting units are disclosed in which a feedback control such that rising edge times and falling edge times of a PWM waveformed pulse train signal to be supplied to the parallel driven power inverting units are respectively corrected using independent correction signals is carried out to eliminate a deviation between output currents of the parallel driven power inverting units. The correction of the rising edge times and falling edge times is such that a phase advance correction for the one unit with respect to an offset value delay and a phase retardation correction for the other unit with respect to the offset value delay are carried out so that a delay of an average output current with respect to the PWM waveformed pulse train signal is made constant. In addition, if an integration calculation of the feedback control is carried out during a constant period of time upon a change in the PWM waveformed pulse train signal to suppress an abnormal integration. Ripple components due to a generation of output current unbalance can be suppressed by limiting the corrections to the falling edges and rising edges of the PWM pulse train signal to either one according to a polarity of the deviation between the output currents of the power inverting units.