| 摘要 |
PURPOSE:To prevent failure, in which a large number of ripples are generated in a DC circuit, and to continue operation safely by forming chopper currents in an irregular waveform by controlling PWM carrier phase so that the relationship of phase difference among each group of resistance chopper devices consisting of a plurality of groups is brought to 360 deg./operation groups at all times. CONSTITUTION:Group start-stop signals are input in PWM carrier generating circuits, in which the failure of chopper converters is generated, and the phase correction signals of each group of each PWM carrier generating circuit are output by a carrier phase correction circuit 28. A signal, which advances at 60 deg. from a phase shifting data and phase of which is shifted, is output from the carrier phase correction circuit 28 in the PWM carrier generating circuit 23, and input to a bit counter 25 by a phase reference signal at 180 deg. and an arithmetic circuit 42 through a changeover switch 41. According to such operation, a power converter is operated by phase shifting relationship, in which carrier signals are shifted at 120 deg. respectively, from phase shifting relationship, in which the carrier signals are shifted at 90 deg. respectively, in the PWM carrier generating circuits. |
