Making your own inverters

william chan

Hey,

Anybody knows how to make a 12v DC to 240v AC 1KW sine wave inverter without bulky transformers?

Thanks.

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www.fd.com.my
www.mercedes.com.my

Mike Green

There is no way to provide the kind of stepup in voltage at the power levels you're talking about without transformers and, at the power level you want, they will be bulky. That said, the better the magnetic materials, the more efficient the transformer will be and the less material you'll need for the core. The better the winding materials and insulating materials, the less material you'll need. For example, very pure copper tape windings may be best for the primary winding given the amount of current involved.

Beau Schwabe

william chan,

Mike is correct, also consider that on your 12v side even if you had 90% conversion efficiency, that you will need to deal with 92 amps.

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

william chan

Is it true that a sine wave inverter will create a lot of heating on the transistors due to a need for the transistor to be in linear mode?
( instead of totally on or off )

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www.fd.com.my
www.mercedes.com.my

Beau Schwabe

william chan,

Running in linear mode is not done in practice, especially with the amount of power you are looking for. Instead, the MOSFET transistors are switched at a very high frequency to create a PWM that has an equivalent "power under the curve" of the intended Sine wave. The output is then filtered with a LC tank tuned to 60Hz or 50Hz depending on what country you live in.

Running in linear mode defeats the purpose of why (in most cases) you would even have an inverter. For example, if you are solar or wind charging your batteries that you are inverting, you want to waste as little power as possible. Running in linear mode is extremely wasteful.

This company makes some great "true-sine" inverters for a reasonable price (about $0.50 per Watt). I have two 300 Watt inverters and one of their 1000 Watt inverters. They all run amazingly cool with fairly decent load demands. Earlier today I had been running one of the 300 Watt inverters with a 200 Watt load for most of the day (10:00am to 7pm) and it was barely warm.

http://www.aimscorp.net/pure.htm

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.