Home-made inverter - Page 1
Forum section: electronics / projects

author: VanMarco
author_rank: Contributor
timestamp: March 18, 2022, 12:34:10 pm
content: Hello!I am planning to build a "pure sine wave" inverter to power some things with solar.I plan to do 2 stages. 1st stage, regular 12v to 350v square wave, second stage, 350v to 220v sine via a egs002 module.now i did a sketch of the 1st stage side, and i am not sure if it's wrong.Output A and B will go to SG3525 driver circuit, not pictured yet.Is there anything essentially wrong?thanks in advance

author: TheMG
author_rank: Frequent Contributor
timestamp: March 18, 2022, 06:32:49 pm
content: What kind of inverter topology are you aiming for? There are many different ways of making a sinewave inverter. The most popular ones:A) Generate a positive and negative high voltage DC rails using SMPS, followed by a half bridge PWM switcher (similar to class D audio amp).B) PWM the main SMPS step-up transformer in such a way as to obtain a rectified sine wave at the output, and follow that up with a H-bridge IGBT switch on the output to be able to "flip" each half of the sinewave on the zero crossings to obtain your positive and negative going peaks.C) Full bridge PWM switching a mains frequency step-up transformer, obtaining the high voltage output sinewave in essentially one step.

author: VanMarco
author_rank: Contributor
timestamp: March 19, 2022, 03:07:45 am
content: I think it qualifies for A)some similar to this for the 1st stageThank you!

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 19, 2022, 03:44:16 am
content: A good starting point:https://sound-au.com/project89.htmTo adapt it for your application, redesign the output section for higher voltage.

author: VanMarco
author_rank: Contributor
timestamp: March 25, 2022, 04:38:31 pm
content: I made a new schematic, i still need to finish the output. Do you like it?thanks

author: moffy
author_rank: Super Contributor
timestamp: March 25, 2022, 10:13:58 pm
content: It is unusual to see what appears to be two transformers, after the bridge rectifiers, in parallel. It is very difficult to match two separate transformers exactly, so one will tend to carry more load than the other. If you want to use two transformers, it is better in series, but what is really better than two is one suitably sized transformer. If I have misread your intentions I look forward to your explanation.

author: VanMarco
author_rank: Contributor
timestamp: March 26, 2022, 04:10:09 am
content: hmm, i want to add more transformers and mos groups in order to have more W output.this module on ali is a lot like what i plan to do, without the side-boardshttps://www.aliexpress.com/item/32985499596.html

author: moffy
author_rank: Super Contributor
timestamp: March 26, 2022, 05:01:52 am
content: This article:https://www.facilitiesnet.com/whitepapers/pdfs/SchneiderElectric_111711.pdftalks about paralleling transformer secondaries, which is related to what you are intending to do. The advantage you have is that the bridge rectifiers will prevent circulating currents, but not the load sharing mismatch if there is any. What is your intended configuration after the bridge rectification?

author: Renate
author_rank: Super Contributor
timestamp: March 27, 2022, 06:50:03 pm
content: Huh? an old CD4047 driving your MOSFETs? That's going to be some sloppy drive, isn't it?

author: Seekonk
author_rank: Super Contributor
timestamp: March 28, 2022, 01:28:11 pm
content: IR2153 makes a nice oscillator driver for this application. I used to buy these on a board with FET and heatsinks for $7 shipped look up 300W inverter board. Now they are more expensive and you don't know what you will get, sometimes SG2453.