| 摘要 |
PROBLEM TO BE SOLVED: To detect the interruption or the open-phase in a commercial power supply and improve the operation reliability of a PWM control self-excited rectifier by a method wherein the deviations between respective instructed phase current values and respective detected phase current values are full-wave rectified and smoothed and a power supply abnormality detector which detects that the rectified and smoothed value exceeds a predetermined judging value is provided. SOLUTION: PWM controlled self-excited rectifiers 40, 50, 60, 70 and 80 have power supply abnormality detectors 41, 51, 61, 71 and 81 respectively and, if some of the power supply abnormality detectors are operated, the operations of the corresponding PWM controlled self-excited rectifiers are stopped. For instance, in the power supply abnormality detector 41 of the PWM control self-excited rectifier 40, the respective deviations between respective instructed phase current values iR*, iS* and iT* and respective detected phase current values are obtained by adders and the obtained deviations are rectified by a full-wave rectifier and the rectified value is smoothed by a filter and, if the output value of the filter exceeds a predetermined value, a comparator is operated and an abnormality detection signal is outputted. |
