DC to AC inverter

[ssembo]

Hello guys,

i am really tired of this load shedding in my country (Uganda). I am requesting for a step by step guide to making my own inverter to run my tv and a 3 lights. Please help. where do i start from?

col

 

[Reloadron]

There seems to be a run on this topic lately. You may want to give this thread a read.

Ron

 

[Grossel]

Hi.

The requirement for having your tv to be part of the load, that would make square wave inverter out of the question.

Answer to that depends on:

• Battery voltage
• In general: is electric components easilly avaiable where you are?
• If you where able to get a ready made inverter, have you considered cost compared to making one yourself?

For a really simple sine inverter - this is the basic stages (not in spesific order)

• Power stage (boost converter) to make 12V -> 220 * sqrt2 = 330V (ca)
• Sine wave generator - 50 Hz
• Circuit to phase shift the 50 Hz signal. An opamp inbverter could do that.
• Two separate buck output stages, take supply voltage from 330V
• Two separate choppes/compare circuits that compares a voltage division from output stages with 50 Hz signal.

All this must be familiar to you before building one.

 

[Boncuk]

Hi ssembo,

before you try building your own inverter I recommend to search the internet for pure sine inverters made in China.

A 1,000W pure sine inverter is about US$60. They are sold in Thailand and used for TV and movies (from CDs) on cross country buses. They work pretty reliably.

Boncuk

 

[Reloadron]

Hi Grossel

My TV (and my computers) work fine on a modified sine wave inverter. My longest test runs being about an hour and never a problem. While given a choice I would obviously take a sine but the outputs of my inverters seem to power things fine, including the cordless phones wall wart supplies. While during a power failure the longest they would normally run on inverter is less than ten seconds before my generator is online, I have never had a problem during test with the modified sine from my inverters.

Ron

 

[Reloadron]

Hi ssembo,

before you try building your own inverter I recommend to search the internet for pure sine inverters made in China.

A 1,000W pure sine inverter is about US$60. They are sold in Thailand and used for TV and movies (from CDs) on cross country buses. They work pretty reliably.

Boncuk

I want one of those. Got any links Hans? That is dirt cheap.

Ron

 

[SABorn]

Dont buy a Chinese made "PowerJack" inverter as they have a very good history of reliably letting the magic smoke out, and at times going up in flames.

There are many other Chinese ones that have a far better reliability.

To change some of your lighting to LED lights would solve the problem of needing mains power for lighting and then that just leaves the need for power for the tv, which would then require a smaller inverter and less cost, this will also reduce the battery bank size required to (and reduce the cost as well) as the led lights will use far less power than standard mains lights.

 

[Boncuk]

I want one of those. Got any links Hans? That is dirt cheap.

Ron

Hi Ron,

get yourself a company name (doesn't really have to be a company - just a good company name) and sign up at https://www.globalsources.com/

Find a manufacturer making inverters which is not located on China main land (e.g. Shenszhen) but check out Taiwan manufacturers. (I know Taiwan isn't part of China, but it depends a lot on China.)

Taiwan sales representatives are mostly females and just let out some of your charm to obtain a good offer. They usually like good personal contact and it might not be a mistake to contact them via Skype. (I have done so and got connectors free and shipped on the expense of the sales representative.)

I'm also in contact with a solar panel manufacturer located on China mainland. They reduced prices for panels from US$4/W to 2$ for both types, mono- and polycrystalline.

Their offer goes to 250W per panel of reasonable size with a strong aluminum frame and heat reducing elements. I will use two 90W monocrystalline panels for garden illumination of my house.

UPSes are also dirt cheap in China. The only thing you have to do is taking that thing apart and resolder the PCB. Mine has been working for three months before it quit. After resoldering it has been working for six years without any problem - and it is still in use.

Mine has a switching time of 5ms at mains failure, ensuring safe power supply for the PC.

Regards

Hans

 

[Reloadron]

Thanks Hans, especially for the added info. There is some really cool stuff pouring in from China. Those small panel meters for example at a few bucks apiece.

Ron

 

[geraldfryjr]

Your Typical computer UPS runs on 12v sealed lead acid batteries it is possible to get one as they are fairly cheap these days and run it off of some deep cycle car batteries.

jer

 

[BrownOut]

Hi Grossel

My TV (and my computers) work fine on a modified sine wave inverter. My longest test runs being about an hour and never a problem. ... the outputs of my inverters seem to power things fine, including the cordless phones wall wart supplies. While during a power failure the longest they would normally run on inverter is less than ten seconds before my generator is online, I have never had a problem during test with the modified sine from my inverters.

Ron

I thought that was an odd comment too. My TV also works fine on the "modified" sine wave convertor. However, I ran for four days, not ten seconds The only thing I found to not run on it are things with motors. For example, I tried running a small air compressor on it, no dice.

 

[Boncuk]

The only thing I found to not run on it are things with motors. For example, I tried running a small air compressor on it, no dice.

If you take the motor apart (already difficult since the motor shields with bearings are bolted to the body (instead using screws)) you will see why it won't run on a modified sine wave.

The rotor is just a piece of iron with an embedded single turn aluminum wire. Trying to run such a piece of garbage off a phase control circuit you'll have real fun.

The motor jerks and runs opposite every once in a while despite zero crossing and constant phase angle.

I had extreme trouble designing a phase control circuit (1.5 to 4.5KW) for a fan manufacturer and finally abandoned the project since it didn't meet the customer's requirement for low cost.

Boncuk

 

[ssembo]

Having to acquire an inverter from abroad can cost me much. Someone told me that he can make an inverter that can charge on mains and be able to offer 800W when off mains at a cost of $60 or even less. He wasn't willing to offer me any more information on how but said: One can use a center tap transformer, that offers 800W to provide any highier power using FETS. Developed a passion and now thought i could make 1. The components are available on the market here.

I am realy glad you turned out

 

[Reloadron]

I gave you a link in this thread to another thread where I posted the following:

Most Inverters produce what is called a modified sine wave (which looks nothing like a sine wave) but anyway here is a link to one such version. The link uses a uC (Micro Controller) but note the similarity between the circuit you posted and the linked circuit.

This is a link to pretty much the same circuit by the same author using everyday discreet components to drive the transformer.

The first link provides a good series of wave forms.

In most cases it is easier to buy than roll your own but for those who wish to build their own you will see pretty much all versions look the same as far as two transistors of sorts driving a transformer. While some critical systems need a true sine wave a device like a light bulb really doesn't care.

<EDIT> Something to keep in mind as mentioned is for every 100 watts out you will draw about 10 amps of 12 volt power. Keep that in mind for the feed wire from the 12 volt source and power to the MOSFETS. Also, you gonna need a big battery! </EDIT>

Ron

It includes a few schematics. Was that not what you wanted?

Ron