The inverter power supply consists of an input power circuit, input filter circuit, IGBT three-phase inverter, LC filter, three-phase isolated output circuit, three-phase output feedback circuit, waveform control and drive, three-phase output sampling circuit, microprocessor control circuit, state control, and auxiliary power supply.
Inverter Power Supply Working Principle: Direct current (DC) is connected to the alternating current (AC) power supply through the input power circuit. After a delay, it is sent to the input filter circuit. The filtered DC voltage is then supplied to the IGBT inverter circuit. To ensure voltage stability during three-phase unbalanced operation, the IGBT inverter circuit consists of three identical circuits. Each circuit is composed of a power module IGBT and a high-voltage pulse absorption circuit. A bridge inverter circuit is used, with the three circuits differing only in their output phase, which is 120° apart, while the rest of the circuits are identical.
The three-phase inverter circuit is controlled by a microprocessor, which outputs three-phase sine waves of 0°, 120°, and 240° through the EPROM and D/A conversion on the main control board, and sends them to the signal control board. The three-phase voltage and current sampling signals are converted to analog and then collected and processed by the microprocessor. The three-phase sine waves sent to the signal board are converted into three-phase SPWM waves using advanced sine pulse width modulation (SPWM) technology, which are then supplied to three groups of IGBT isolation driver circuits to drive the IGBTs, producing amplified SPWM waves. These waves are further filtered through an LC filter, output transformer, and output filter circuit to yield a stable 50Hz three-phase AC power. The state control circuit primarily handles reset, state indication, fault indication, and output voltage and current sampling signals.
