Solar Energy Inverter

This project has a bit of an experimental character and essentially consists of two parts:

• A DC to DC converter that brings the battery voltage from nominal 48V (the batteries are charged by PV modules) to 350V.
• An inverter that generates 230V AC (50Hz) from 350V DC.

The DC-to-DC converter is of course protected against all adverse reactions (undervoltage, overvoltage, overcurrent, overtemperature,..) and is designed for high efficiency.

The output voltage (nominal 350V DC) is galvanically isolated from the input voltage and can be adjusted in the range of 280V to 380V. This is necessary to feed energy into an existing 230V grid in conjunction with the inverter.

The inverter generates a short-circuit-proof, 230V sine AC voltage from the nominal 350V DC, previously with the DC DC converter.

 

To be flexible, the control voltages for the IGPTs come from a small extra board attached:

 

I have chosen two development steps here: First, to generate only the 230V AC (not synchronized). Here the control signals are generated with an ASIC.

In the second step, synchronize the 230V with the external mains voltage and then also add energy to this external mains. Here the control signals are generated with an STM32.