XINLI BOILER

Causes of Overvoltage of Biomass Boiler Frequency Converter

10 Dec, 2021

　　Causes of inverter overvoltage

　　(1) The overvoltage that appears in the breaking transformer is based on the theory that the overvoltage is blocked. When the transformer is disconnected, the current in the transformer's inductance cannot change suddenly, and the magnetic field energy stored in it will oscillate between the transformer's magnetizing inductance and the capacitance to ground. Overvoltage has occurred.

　　(2) Overvoltage generated by the transformer with load closing In the actual test, the no-load transformer has detected an overvoltage several times the power supply voltage. The physical principle is: the no-load transformer can still be equal to an excitation inductance and The equivalent capacitance of the transformer itself is connected in parallel. If the neutral point of the transformer is not grounded, the switch is closed again (one-phase or two-phase first), and oscillations occur due to feeder capacitance, transformer-to-ground capacitance, longitudinal capacitance, and transformer inductance. , The result is a higher overvoltage, especially a higher overvoltage at the neutral point of the transformer. Although the transformer is basically closed with a load, the overvoltage will also be generated when the transformer is closed with a load, but it is smaller than when it is under no load. There is a relatively large capacitance in the real load, because the energy storage of the capacitance will not increase suddenly, and the transmission cable has distributed ground capacitance when transmitting high-frequency oscillating voltage, these capacitances have an absorbing effect on overvoltage. The combined effect of the two makes the overvoltage of the transformer in the closing process suppressed, but sometimes its value is still very high, and it may even be higher than the withstand voltage value of the component, which is very dangerous.

　　(3) The commutation overvoltage of the rectifier element is very high when the rectifier element is commutation, so the steering overvoltage is also very high. This will not only damage the components, but also generate electromagnetic interference.