Grid Tie Inverter

The 300W Grid tie inverter for home application:

1. Schematics and simulation

This project use an old UPS transformer for grid connect (For step-up and isolate voltage between Grid and Batterry). Main diagram PWM control use TL494 and LM324 for full-wave precision rectifier. An old radio transformer 220/12V for voltage measurement and synchronization.

Below is the schematics and some project GTI Image

Fig 1: GTI simulate by psim 9.01

Note 1:  Change DC voltage source will change the power injection into grid

Note 2:  Change the phase of synchronous voltage will change the reactive power (Look like STACOM) from negative or positive angle

Note 3:  If modulation index is low, the DC link voltage will increase too high and dangerous to FET switch

2. Implementation use TL494, LM32, PIC16f628a for frequency and synchronous protection