Simple operation manner null of three phase circuit sine wave PWM in

摘要

PURPOSE:To reduce an arithmetic time to be required by performing arithmetic for a command period on two phases in the threephase output AC of an inverter, and by setting the reduced sum of a command period processing value on said two phases from a value multiplied by 3/2 for the period of carrier chopping wave signal, to be the command period processing value on residual one phase. CONSTITUTION:On PWM processing, interruption is to occur by every half cycle of carrier chopping wave signal, and it is judged whether its output is set either on the left or on the right of the center of a carrier cycle. If it is set on the right side, arithmetic is performed on respective periods Tnu, Tnv, Tnw, and the output time of a right side wave-form is set. If it is set on the left side, a short-circuit-proof dead time between the upper and lower arms of an inverter main-circuit switching element is computed, and the output time of a left side waveform is set. As a result, arithmetic steps to be required can be reduced, and the arithmetic periods along with the reduction can be reduced.