| 摘要 |
PURPOSE:To enable to detect an overcurrent at a high speed by discriminating the overcurrent by the current flowed to a current limiting reactor. CONSTITUTION:A load current is flowed to a diode 52 when an OFF signal is applied to a GTO50. A current of a current limiting reactor 3 is circulated through a diode 4, and a main circuit current is zero at this time. When GTOs 51 of paired arms are then turned ON, a current of the direction for cancelling the current of a diode 52 is flowed from a DC power source 1. Further, when the diode 42 is recovered by a reverse current, a main circuit current is moved to a route for charging a snubber capacitor 58 of the GTO50. After the capacitor 58 of the GTO50 reaches a power source voltage, only the GTO51 becomes conductive state. The current flowed to the reactor 3 is detected by a current detector 8, compared with the set value by a comparator 9, thereby discriminating the overcurrent. |
