Transformer less inverter

[Mithun_K_Das]

Hi,
Have you any idea to design a transformer less inverter? Or how can we design a transformer less inverter circuit? will it be efficient enough? suggest me pls...

Thanks
_Mithun

 

[Tahmid]

Hi,
I guess one method is to use an inductor-based high frequency boost circuit followed by a full-bridge.
Since you're from Dhaka, I think you mean without using the large linear transformer. In that case, you can use SMPS, using really small and cheap ferrite transformer and high frequency circuitry.

Hope this helps.
Tahmid.

 

[Mithun_K_Das]

Thanks a lot.

its a great idea. I wish as: 1st, 12VDC to 300VDC. 2nd 300VDC to 220V ac sine wave.

but problem is in the second step. what can I do here?

 

[Tahmid]

Hi,
If you want to make sine wave, step up first to 350 to 360 VAC, not 300. It would be better if you use ferrite core transformer through push-pull instead of boost topology.
Second part requires you to use a micrcontroller unless you want to go to very complex hardware with discrete components.
Most inverters here are square/modified square wave. Unless you go over 600W to drive fridge or AC, I guess you don't really need sine wave.

Hope this helps.
Tahmid.

 

[Audioguru]

Most inverters here are square/modified square wave. Unless you go over 600W to drive fridge or AC, I guess you don't really need sine wave.

Cheap and old inverters have a square-wave output. They can drive incandescent light bulbs and heaters but their peak voltage is too low for modern electronic products and motor speed controllers.

Cheap Chinese inverters use a TL494 IC as a high frequency oscillator which is amplified and drives a ferrite stepup transformer which is rectified and filtered into 350VDC. Then a second TL494 IC is used with a sine-wave oscillator to make a PWM signal to Mosfets that drive a smoothing filter.

 

[Mithun_K_Das]

350VDC to 220VAC. How?

 

[Audioguru]

350VDC to 220VAC. How?

220VAC has a peak voltage of 311V. 240VAC has a peak voltage of 340V.
The 350VDC powers an H-bridge that is driven from a high frequency PWM signal that is modulated with a 50Hz sine-wave. Feedback is used to change the duty-cycle of the PWM for voltage regulation.

 

[Bharathi1]

220VAC has a peak voltage of 311V. 240VAC has a peak voltage of 340V.
The 350VDC powers an H-bridge that is driven from a high frequency PWM signal that is modulated with a 50Hz sine-wave. Feedback is used to change the duty-cycle of the PWM for voltage regulation.

Hi sir even i am also designing the inverter without transformer , am having 12v dc that i want to convert to 230Vac please suggest me some circuit

 

[Audioguru]

I am in Canada where electricity is reliable and inexpensive. Therefore I have never needed and never used an inverter.
There are inverters available that are sold to hunters and fishermen but I have never looked at them. Probably all of them use a transformer.
Maybe you can find a circuit yourself.