| 摘要 |
PURPOSE: An arm short discrimination circuit is provided to shut off switching elements by discriminating arm short status from control signals applied to switching elements of a half bridge circuit. CONSTITUTION: A circuit comprises an upper gate buffer(10), a lower gate buffer(20), a half bridge circuit(30), and a short discrimination circuit(40). The short discrimination circuit is configured in that LEDs of first and second photo-couplers(op1,op2) are connected in serial between the first gate resistance(Rg1) and the first switching element(Q1) of the half bridge circuit, and between the second gate resistance(Rg2) and the second switching element(Q2) of the half bridge circuit, respectively, diodes(D1,D2) are connected in reverse direction and in parallel to the LEDs of the first and second photo-couplers, a collector of a light receiving transistor of the first and second photo-couplers is connected to an auxiliary power, an emitter is connected to a current detection resistance(Rs), a contact of the photo-couplers and the current detection resistance is connected to a non-inverting input port of a comparator(u1), an inverting input port of the comparator is connected to a contact of two resistances connected to the auxiliary power and ground, and an output of the comparator is output as a short discrimination signal.
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