The inverter three phase online ups stage one pair amplifier transistor is damaged, replace the same type of transistor after running for some time because they burn too much current, caused by excessive current reasons:
- Overcurrent failure. When the inverter output overcurrent, the overcurrent protection circuit does not work;
- Pulse Width Modulation (PWM) component failure, the two complementary output waveform asymmetry, a long lead-time, on-time and short the other, so that the work of unbalanced arms, even the arms are turned on simultaneously, resulting in two tube is damaged;
- Power difference between the larger tube parameters, then even if the input waveform symmetry, the output will be asymmetrical, the waveform is output transformer, causing magnetic bias, ie the flux imbalance, leading to the accumulation of down transformer saturation current surge, burn power tube, and a burn, the other also will burn.
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