| 摘要 |
PURPOSE:To reduce a gate circuit failure by detecting a load current controlled by a self-extinguishing type semiconductor element and coupling a detection current and an OFF pulse current of a gate controller in reverse polariry as a magnetomotive force of a saturable reactor. CONSTITUTION:A capcitor 3 is connected through a reactor 2 to a DC power source 1, and a parallel circuit of a series circuit of a load resistor 4, an inductance 5 and a DC current detector 20, and a freewheel diode 6 is connected to the positive electrode side of the capacitor 3. The other end of the diode 6 is connected with the anode of a main self-extinguishing type semiconductor element 7, and the cathode of the element 7 is connected to the negative electrode side of the capacitor 3. The gate of the element 7 is connected at the starting end through the end of a winding NOFF of a core 22 of a saturable reactor to the negative electrode side of a reverse bias DC power source 11. A current proportional to the load current of the element 7 is applied through the detector 20 and a converter 21 to the winding NB of the core 22 in reverse polarity to the magnetomotive force of the winding NOFF. Thus, a gate circuit loss can be reduced. |
