| 摘要 |
PURPOSE: A surge voltage and overcurrent protective circuit is provided to protect an inverter circuit of an intelligent power module from the surge voltage and the overcurrent. CONSTITUTION: The surge voltage and overcurrent protective circuit for an inverter circuit comprises two transistors(Q1,Q2), a resistor(R2) connected to the emitter terminal of the transistor, a transistor(Q5) connected to the resistor(R2), a diode(D2) connected in parallel with the resistor(R2), a resistor(R1) connected between the emitter terminal of the transistor and the resistor(R2), a diode(D1) and a comparator(U1) connected in parallel with the resistor(R1), a resistor(R3) and an input port of a comparator(U2) connected to the selection ports of the comparator(U1), the grounded output port of the comparator(U2), a transistor(Q3) and a resistor(R4) connected in parallel with the selection ports of the comparator(U2), a grounded emitter of the transistor(Q3), a condenser(C1) and a resistor(R5) connected in parallel with the base terminal of the transistor(Q3), a resistor(R8) connected between the other terminal of the condenser(C1) and the emitter of a transistor(Q4), the collector of the transistor(Q4) connected between the gate of a transistor(Q5) and the resistor(R2), a resistor(R7) and a condenser(C6) connected in parallel with the base terminal of the transistor(Q4), the other terminal of the transistor(R7) connected to the emitter of the transistor(Q5), the resistor(R6) connected between the emitter of the transistor(Q4) and the resistor(R6). The off operation of the transistor(Q5) smoothes the surge voltage generated by the reverse recovery operation. When an overcurrent flows the circuit during the on state of the transistor(Q5), the transistor(Q5) is turned off to prevent the components of the circuit from damage.
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