Voltage Balancing at the Output of Three-Phase Semiconductor Converter

The article describes the methods of balancing the voltage in a three-phase power supply system containing a semiconductor three-phase bridge inverter as an energy source. It is shown that in the simplest case, a stepwise voltage form can be formed instead of a sinusoidal voltage. At the same time, for a 180-degree switching of power switches, the content of the first voltage harmonic will be 0.955, which is acceptable for most consumers, especially in rural areas. However, at the same time the issues of balancing are greatly simplified and come down to push-button opening of keys in an additional, fourth inverter rack. The article presents an algorithm for controlling an additional inverter rack based on the conditions for ensuring a given accuracy of balancing the output voltage. The specified algorithm is implemented by PWM voltage regulation on the corresponding keys of the additional rack based on information received from the sensor in phase voltage or voltage of each phase relative to one of the inverter buses.