| 摘要 |
PROBLEM TO BE SOLVED: To suppress fluctuation in the torque generated from a load motor by preventing fluctuation in the output current at the time of switching the PWM modulation system. SOLUTION: The series multiplex inverter comprises circuits 1a, 1b for setting the amplitude and period of carrier for unipolar and dipolar modulation, a circuit 2 for selecting the output from the circuits 1a, 1b, a triangular wave generation circuit 3 for generating a selected carrier, a circuit 4b for setting a switching timing when each carrier for each modulation system has a phase value which can be switched, and a circuit 5 for setting a phase such that the carrier is connected continuously at a switching point. Amplitude and period of the carrier are then varied along with the phase thereof and the value of carrier is connected continuously thus switching the modulation system. Furthermore, a three-phase voltage command correction means 12a adds a correction amount to a three-phase voltage command only for a predetermined interval such that the time averaged three-phase output voltage will be equal to the three-phase voltage command after pulse width modulation thus switching the modulation system. |
