| 摘要 |
PROBLEM TO BE SOLVED: To surely protect an inverter with a comparatively simplified structure without resulting in increase of capacity of an element. SOLUTION: In this method, a primary winding 21 of a transformer 2 is connected in series to a system power supply, a secondary winding 22 of the transformer 2 is connected to the AC output side of an inverter 3 and an AC output voltage of this inverter 3 is added in series to the power supply voltage via the transformer 2. In this case, a tertiary winding 23 is provided to the transformer 2, a semiconductor switch 6 is connected to both terminals thereof, both terminals of the tertiary winding 23 are terminated through the on-state of the semiconductor switch 6 when an over-current flows into the primary winding 21 and thereafter the inverter 3 is gate-blocked. |
