24V1000W pure hardware pure sine wave inverter design

This inverter has the following features:

1. Single polarity frequency multiplication modulation, the carrier is set to 14.7K, and the actual post-stage LC works at the multiplication frequency of 29.4K;

2. Added soft start;

3. DC feedback improves stability and voltage regulation accuracy;

4. The reference sine wave and triangle wave use the same circuit structure, that is, they are both filtered from square waves to reference sine waves and triangle waves. When the temperature changes, although the amplitudes of the reference sine wave and triangle wave will change slightly, they cancel each other out after modulation, so the temperature stability is excellent;

5. The circuit is simple and the cost is low, much lower than that of single chip microcomputer;

6. Superior performance, fast response speed and high voltage stabilization accuracy.

Circuit diagram:

The actual circuit built on the 24V1000W square wave board:

Pre-stage power tube: RU75N08*4

Transformer: EC42-20, primary 4+4, secondary 64

Rectifier diode: RHRP860

Post-stage power tube: FQA24N50

Simulation of a reference sine wave:

The measured waveform of the 50HZ reference square wave:

The measured waveform of the 50HZ reference sine wave:

The measured waveform of 14.7K triangle wave carrier:

The waveform of the D pole of the no-load front-stage MOS when the input is 24V:

The waveform of the D pole of the front-stage MOS when the input is 24V and the full load is 1000W:

SPWM drive waveform of the low-end MOS in the rear stage:

The waveform of 220VAC output when input is 24V and no-load is:

After taking on the full load of 1000W, the voltage drops to 220V, and the load adjustment rate is (222-220)/222=0.9%.

When fully loaded, the input voltage is lowered from the original 24V to 20V. At this time, the DC high voltage is only 300V, the waveform is clipped, but the voltage is still stable at 219V.