Causes and treatment methods of inverter overvoltage

1. According to the theory of cutting off the overvoltage, when the transformer is cut off, the current in the transformer inductance cannot be abruptly changed, and the stored magnetic field energy forms a vibration between the excitation inductance of the transformer and the ground capacitor, and the overvoltage occurs.

2. The overvoltage generated by the transformer with load is turned on in the actual test, the overvoltage transformer detects several times of the overvoltage of the power supply voltage, and its physical principle is that the parallel connection of the no-load transformer and the equivalent capacitor of the transformer itself is equivalent, if the neutral point of the transformer is not grounded, the switch is non-periodic (one phase or two phases first), due to the vibration of the feeder capacitor, the transformer to the ground capacitor, the longitudinal capacitor and the transformer capacitor, the result is high overvoltage, especially the high overvoltage of the transformer neutral point. The transformer is basically turned on with load, but the transformer will also produce voltage after being turned on with load, but it is relatively small when there is no load. The real load has a relatively large capacity, and the storage of the capacity will not increase suddenly, so the transmission cable is distributed on the ground capacity when transmitting high-frequency vibration voltage, and these capacities have an absorption effect on the overvoltage. The combined effect of these two suppresses the overvoltage of the transformer during the turn-on process, but sometimes the value is still very high, and it may even exceed the withstand voltage value of the part. This is very dangerous.

3. The commutation overvoltage rectifier element of the rectifier element is high due to the high steering overvoltage when commutating. Not only does this damage the parts, but it also creates electromagnetic interference.

Causes and treatment methods of inverter overvoltage

Causes and treatment methods of inverter overvoltage

How to deal with the overvoltage of the inverter.

1. For the fracture overvoltage of the inverter phase-shifting transformer, the overvoltage absorption loop is formed through the resistance absorption network and the zinc oxide arrester, and good results have been obtained.

2. For the overvoltage generated by the transformer with load on, the transformer with good periodic performance (there will be different periods after long-term operation of the switch), the transformer with good resistance absorption loop and active suppressor technical scheme, and the transformer with electrostatic shielding measures can also effectively suppress the pass-through voltage. However, it is difficult to make an electrostatic shield for high-power transformers.

3. Replace the overvoltage generated by the rectifier parts, pay attention to the sufficient reverse withstand voltage value of the rectifier parts, and then take appropriate measures for the absorption circuit and the continuation circuit. Otherwise, the rectifier equipment may be destroyed by overvoltage.

4. The overvoltage when the inverter is working is basically when the transformer is closed separately, so the method of suppressing the overvoltage of the inverter should be considered from the transformer. It can be used:

(1) Increase the excitation inductance of the transformer and the capacitor to the ground, increase the excitation inductance, reduce the no-load current, and increase the cost of the transformer.

(2) Enlarge transformer-to-ground capacitors: In principle, it is easy to analyze, but in fact, due to the limitations of the structure and materials of the transformer itself, it is impossible to make any transformer with high insulation mode and insulation grade, so it is also quite difficult to greatly increase the transformer-to-ground capacitor.

Causes and treatment methods of inverter overvoltage

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