| 摘要 |
PURPOSE:To prevent the breakage of the semiconductor element of a bidirectional converter by a resonance current when the resonance by a filter capacitor and the impedance of a line occurs, in the case that the bidirectional converter is operating as a converter. CONSTITUTION:The current of a system is detected by a current transformer 48, and is given to a high-pass filter 52. When resonance phenomena occur, the of resonance components frequency are extracted from the high-pass filter 52. The output of the high-pass fitter 52 is smoothed by a smoothing circuit 62, and is given to a comparator 64. Accordingly, when resonance occurs, a high level of signal is outputted from a comparator 64, and circuit protectors 46a and 46b operate according to this signal, and a bidirectional comparator 38 is cut off from a commercial power source 36, that is, the system. |
