DC/DC converter for inverter

[Manni]

Hi everyone,

I want to design a DC/DC converter that can produce half-waves for a grid tie inverter. The nominal input voltage is 41V and the ouput power is about 400W. Output voltage is 250V RMS, so I need about 350V peak voltage. The targeted efficiency is 96% or higher. I have looked at various topologies, especially interleaved Flyback Converters, LLC Converters and the Push-Pull Converter. At this point I believe the best way to move forward is using a push-pull converter, but I am open for other suggestions! Is it possible to achieve the targeted efficiency of 96% with a push-pull converter and how do I need to design the transformer in order to achieve that?

Regards

 

[BradtheRad]

Simplistic simulation showing operation in a grid-tied inverter.

Link to Falstad's animated interactive simulator. Clicking it:

* opens website falstad.com/circuit
* loads my schematic
* runs it on your computer.

https://tinyurl.com/2f8eto88

1) House voltage provides AC bias signals to H-bridge. Power supply is single polarity.

2) H-bridge sends 41 V_peak AC (several Amperes) to transformer primary.

3) Transformer steps up AC manifold (10 X).

4) Transformer secondary sends 230 VAC (a few Amperes) to grid.

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Overall parasitic resistance has to be minimized.

For the system to carry hundreds of Watts, it seems more practical to utilize the entire primary full time, rather than make a center-tapped primary switch alternately between the halves and furthermore step up voltage 20X through each half.