| 摘要 |
PURPOSE:To do a switching operation without a phase shift by switching from three pulses to one pulse or vice versa at a specified timing separately for each of the U, V and W phases when controlling a switching operation of a PWM inverter. CONSTITUTION:A latch 3 which stores one-pulse pulse width data and a latch 4 which stores three-pulse pulse width data are installed on data buses 1, 2. Through data buses 5, 6, the data of each of the latches 3 and 4 is output to U-phase, V-phase and W-phase switching circuits 7u, 7v and 7w. Due to an AND logic of timing signals 8u-8w which provide a switching trigger and a one-pulse/three-pulse switching command signal 9, a one-pulse gate signal and a three-pulse gate signal are output, being shifted, from the switching circuits 7u-7w. The switching from the one-pulse gate signal to the three-phase one or vice versa is conducted at a timing when the maximum value or the minimum value of a fundamental wave component of each phase is reached. By this method, the switching can be done without a phase shift. |
