CURRENT INSTANTANEOUS-VALUE CONTROL TYPE PWM INVERTER

摘要

PURPOSE:To prevent the generation of a ripple component by calculating the mean value of three-phase ACs and subtracting only the mean value from the currents of each phase. CONSTITUTION:A current instantaneous-value control type PWM inverter is composed of a current regulator 1, a comparator 2, a three-phase triangular- wave generating circuit 3, a main circuit 4 constituting the inverter, a current detector 6, etc., and supplies load 5 with electric power. A mean value circuit 8 arithmetically operating a mean value and an addition circuit 9 are mounted, and the mean value circuit 8 prepares (-1/3) times a-s high as the sum of each output from the current regulators 1a-1c and outputs them. When the sum total of voltage commands at points U-W is brought to zero, the mean value circuit 8 outputs zero, but the mean value circuit 8 operates so that the sum total is brought to zero in voltage commands output from the addition circuits 9a-9c when the sum total of U-W are not brought to zero, and output voltage can be adjusted so as to be balanced at all times.