| 摘要 |
PROBLEM TO BE SOLVED: To prevent the burning of a load and a device abnormality which are caused by an abnormal current in an oscillation state induced by positive feedback such that harmonic components outputted by an inverter is applied to a capacitor on a load side. SOLUTION: In an oscillation state, a load current with a frequency close to the carrier frequency of an inverter flows heavily. Carrier frequency components are extracted from the load current by a band-pass filter 11 and rectified by a rectifier circuit 12. The rectified output is compared with a set value by a comparator 13 to detect an abnormal current. Only the harmonic wave suppression function of the inverter is stopped automatically for stopping the abnormal current, and the burning, etc., of a load can be prevented. |
