CONTROLLER FOR POWER CONVERTER

PROBLEM TO BE SOLVED: To reduce the switching loss in a power converter. SOLUTION: A steady operation discriminating circuit 80, a DC voltage command generating circuit 90, a DC voltage control circuit 100, a reactive power control circuit 110, and a power control circuit 15 are added to conventional power converters 3A-3D. The circuit 80 inputs the output currents, etc., of the power converters 3A-3D and discriminates the steady operating states of the converters 3A-3D based on the rates of change of the currents, etc., within a prescribed period of time, and the circuit 90 outputs DC voltage commands in accordance with the discriminated results of the circuit 80. The circuit 100 outputs effective component voltages corresponding to the differences between the DC voltage command from the circuit 90 and the input DC voltages of the converters 3A-3D, and the circuit 110 outputs the reactive component voltages corresponding to the differences between a reactive command and the reactive power of the converters 3A-3D. The circuit 15 inputs the effective component voltage command, the input DC voltages of the converters 3A-3D, and the reactive component currents of the output DC currents of the converters 3A-3D and outputs signals for controlling the output currents of the converters 3A-3D.