4KW 230V-Inverter

With these schematics and PCB's, you can create your own offgrid 230V AC 4KW inverter. It has been up and running since early 2019, and is used every day. Read Readme.pdf how to do it.

Implementation of an EGS002 with Ardunio Nano

Introduction

The aim of this repo is to help the hobbyist or student make rapid progress in implementing an 230V inverter based on a Arduino Nano and with the use of a EGS002 PCB.

Please also note that:

• It's assumed the reader has a basic understanding of C programming
• It's assumed the reader has a basic understanding of electronic and how to solder
• If you plan on making an inverter please read the safety section

Why EGS002

First, the driver pcb. This is a known solution with EGS002. And why EGS002 ? Because this PCB is dirt cheap on Ebay. Around 5$, so there’s no need for buying extra components, when this board contains half of the components we have to use, for this inverter. It just has to be modified a bit.

1.

Secondly, we need a host for this driver board. My own creation is this small 10x10cm PCB for 2$.

Heres the files so you can make your own PCB:

• "Inverter Controller with SCR 1.1.zip"
• "Power Board 3.8.zip"
• "EMI filter.zip"

https://github.com/tvixen/230V-Inverter/tree/master/230V%20Inverter/doc/download

2.

And for this little controller board we need a little power board. Here I made one with 4 or 8 HY4008 FET’s. Again 10x10cm.

3.

Now a little EMI circuit to sort the spurious frequencies out. Make this filter according to the size of your toroid. PCB 10x10cm. It’s just ferrite with some windings in the right direction.

All PCB’s fabricated in China by JLCPCB. If you chose to fabricate them all together, the prise is 12$ (For 5 of each + postage=14$)

4.

A cheap and reliable power supply….from Ebay 1.25$:

Or one with a little more features 4$:

5.

The cpu for programming purposes. Startup, shutdown, Fan control, volt , amp, watt aso: 1.99$.

Midifying the EGS002

And now for the modification on EGS002. With this modification the inverter can handle current peaks. So hopefully, no more blown FET’s.

With this mod, the SPWM enable pin, can enable and disable the sinewave out. (Same as the Temp method, but the right way to do it).

1. Remove the 8 components with red a cross.
2. Lift pin 7 on the cpu.
3. Mount 3 short wires, where there’s a red line.
4. Move R10 to position C30 (10k/103)

Connections

This is how the PCB's has to be connected inside a metal case.

If the I2C is used, a second Arduino Mega2560 with a display connected, can be used to show the information running around in the little Nano. The Mega is used coz of the more memory as the display is quite demanding with the graphis. Here is my example of the colour display 240x320 I use in my old "Piller UPS" cabinet.

Here I experiment with different types of input. First, the drawing is made in visio and then programmed into Arduino Mega.

Brief Theory

Basic PWM

The Nano can do pulse width modulation’s (PWM), but with a PCB like EGS0002 the energy isn't worth it. The figure below shows an example of a PWM signal.

There are two properties to a PWM signal, the frequency which is determined by the period of the signal and the duty cycle which is determined by the high-time of the signal. The signal in figure above has a period of 250μS which means it switches at 4KHz. The duty-cycle is the percent high time in each period, in the last figure the duty-cycle is 60% because of the high-time and period of 150μS and 250μS respectively. It is the duty-cycle that determines average output voltage. In figure above the duty-cycle of 60% with 5V switching voltage results in 3V average output as shown by the red line. After filtering the output a stable analogue output can be achieved.

Sinusoidal PWM

A sinusoidal PWM (SPWM) signal can be constructed by dynamically changing the duty- cycle. The result is short pulses at the zero-crossings and long pulses at the wave peaks. This can be seen in the figure below.

If we then sends this to a toroid, the voltage vill be amplified, and the 230V RMS can be reached.

Safety

First of all I don't encourage you to make an inverter, I'd prefer that you didn't and I take no responsibilty for your actions. Remember 30mA can be leathal, mains voltage deserves respect!

If you still choose to do so, take basic precautionary steps like: Invest in some terminals and make sure that any high voltage part of the circuit is not touchable; don't modify it while it's power up; Don't do it alone.