About a PWM power inverter

[gaetan8888]

Hello

I was, since few months, looking for an easy to build PWM inverter, and without any PIC programing.

Looking at a 555 PWM amp circuit, I have an ideas, by merging a 500 w sine inverter with the PWM section of the 555 PWM amp circuit it made a PWM inverter.

Here is the final circuit.

http://img205.imageshack.us/img205/4...e500wccpwm.jpg

Any suggestions ?

Thank

Bye

Gaetan

[gaetan8888]

Hello

The PWM section of that home made inverter do have a 100khz frequency and come from this web site;

http://personal.inet.fi/surf/rushi/555d.html

Thank

Bye

Gaetan

[gaetan8888]

Hello

I was looking at a PWM inverter circuit because modified sine inverter are too noisy in TV and audio systems and others things.

I have a 500 w sine inverter schematic, I have the mosfet and few very big ferroresonant transfo, but it would need a very big heat sink and it would lost quite much energies into heat.

Here is the original 500w sine wave circuit.

http://img371.imageshack.us/img371/8...sine500wcc.jpg

Thank

Bye

Gaetan

[zigzagflux]

I tried to build this exact circuit almost 20 years ago, back when all the parts were in full production. I never was able to get it to work. I don't know if my choice of transformer wasn't appropriate, or if the negative feedback wasn't correct. Either way, not a very practical circuit. You are definitely better off with a PWM circuit and modern components. I would 86 the XR-2206, for starters. Better ways of generating clean sine waves with current production.

[gaetan8888]

Hello

Here is a pwm amp I seen, maby by feeding the input by a 60hz sine and modifying the output for using a transformer and that would be a easy to do power inverter ?

http://static1.album.ee/files/77/381...77381_j4rB.jpg

Thank

Bye

Gaetan

[TechGuy]

That inverter design is not a PWM inverter. It uses a PWM circuit to create a Sinewave output to power switching transistors to create a 60 hz output. The power transistor operate in linear mode instead of switchmode which isn't very efficient.

A PWM inverter will switch the power transistors in the Khz range and alter the duty cycle to simulate a sine wave output. The PWM output from the transformer secondary needs either a rectifying bridge/flipping bridge. A PWM output can also be set up using a BTL (Bridge Tied Load) output circuit.

To give you idea how PWM inverter work, research Class-D Amplifiers:
http://en.wikipedia.org/wiki/Electronic_amplifier (for a starting point).

To create a PWM Sinewave output without a Microcontroller (aka PIC) you can do sometime like this:
http://home.c2i.net/helbue/projects/vfd.htm

I recall an app-note from National that created a digital quasi sinewave PWM output generator using a 555, a TTL Counter (maybe a 74193) and either a multiplexor or a CD4017 or Both. Perhaps you can google for it.

Setting up a simple Sinewave generator in a Microcontroller is the easier solution. You just need a create a delay lookup table to drive either a digital output on the uC, or using a PWM controller that is Built into the uC. The PIC 18F1330 is a small uC with four built-in PWM controllers.

We discussed PWM inverters a year or two ago on this forum. A seach might be useful.