Dear all,
I have built igbt dimmer circuit which works fine with resistive load but when I change the load to inductive load the dimming (speed variation of 100 watt universal motor) became barely noticeable. Even when I switch back to the resister load the igbt failed to operate normal. I didnt use any external snubber circuit assuming that the inductive load current is only below 5amps and the igbt I uses is well above this 75amps and 1200v so I guessed the internal free wheeling diode copes with spikes produced. Amazingly very small mosfet works fine irf740 but why not that huge igbt works. I have attached the circuit
I have built igbt dimmer circuit which works fine with resistive load but when I change the load to inductive load the dimming (speed variation of 100 watt universal motor) became barely noticeable. Even when I switch back to the resister load the igbt failed to operate normal. I didnt use any external snubber circuit assuming that the inductive load current is only below 5amps and the igbt I uses is well above this 75amps and 1200v so I guessed the internal free wheeling diode copes with spikes produced. Amazingly very small mosfet works fine irf740 but why not that huge igbt works. I have attached the circuit
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