Abstract: When an over-current is detected as flowing in semiconductor devices of a power converter by a Hall CT (current transformer), an abnormality detection unit outputs an abnormality signal. If the abnormality signal is output from the abnormality detection unit, a gate breaking unit of a gate driving unit outputs a gate breaking signal to stop the power converter. At the same time, a gate ON unit maintains the gate signal of the semiconductor device that has become abnormal in the ON state and, after the current in the semiconductor device has become smaller than a specified value, the gate signal of the semiconductor device is rendered OFF by a gate constriction device. By this operation, the current flowing in the semiconductor device may be reduced prior to any gate breaking operation occurring.

Abstract: A power converting apparatus comprises a converter, a control device, and a protection device. The converter has first and second semiconductor devices coupled in series. The control device outputs a plurality of control signals for switching on the first and second semiconductor devices. The protection device detects the control signals and cuts off the control signals for the first and second semiconductor devices when the control signals for the first and second semiconductor devices are detected simultaneously.