Parallel operation controller for power converters

Claim 1

A parallel operation controller for power converters of the type which performs parallel operation control of a plurality of power converters whose input terminals are connected to a DC voltage source and whose output terminals are connected to each other through reactors said parallel operation controller comprising: a plurality of three-arm modulation control signal generating means for generating three-arm modulation control signals for first, second and third phases of the power converters, respectively, each modulation control signal serving as a voltage command value for each phase of corresponding power converters; voltage fixing period determining means for selecting, on the basis of a three-arm modulation control signal generated by one of said plurality of three-arm modulation control signal generating means, a three-arm modulation control signal of the first phase and for fixing the voltage level of the three-arm modulation control signal of the first phase to a predetermined DC voltage level, and for determining a period of time in which the voltage level is fixed; a plurality of two-arm modulation control signal generating means for generating a fixed voltage command value corresponding to the three-arm modulation control signal selected by the voltage fixing period determining means, and for correcting the three-arm modulation control signals of the second and third phases so as to change the corrected three-arm modulation control signals into two-arm modulation control signals; and a plurality of PWM signal generating means each of which generates PWM signals on the basis of the voltage command value and the two-arm modulation control signals generated by the corresponding two-arm modulation control signal generating means and supplies the PWM signals to the corresponding power converter.