PWM CYCLOCONVERTER AND POWER FAULT DETECTOR

摘要

A PWM cycloconverter is disclosed that can switch power supplies without interrupting operation in the event of a power supply abnormality. When a power supply abnormality occurs in three-phase AC power supply 1, power supply abnormality detection circuit 30 outputs power supply abnormality detection signal 120, whereby power supply switch 20 selects and outputs the output voltage of uninterruptible power supply 10. Phase detection circuit switch 43 selects and outputs phase information that is output from uninterruptible power supply phase detection circuit 41. Uninterruptible power supply phase detection circuit 41 detects the phase of uninterruptible power supply 10 from before the occurrence of the power supply abnormality, whereby accurate phase information of uninterruptible power supply 10 can be output even immediately after phase detection circuit switch 43 switches the phase information that is output. As a result, operation is not interrupted when switching power supplies.