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Steps for high efficiend DC/DC step up converter

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Mithun_K_Das

Mithun_K_Das

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What is the designing steps for high efficient step up DC/DC converter?

power ratings:

12V to 125V DC, 150Watts.
efficiency > 95%.


Any reference?
 

To get 150 W out, you will have to draw 12.5 A avg from your supply. Add another ampere or two to make up for losses.

A boost converter topology (single or interleaved) will need a long duty cycle since you wish to step up 10X. Efficiency is reduced due to such a great a step-up.

You might consider an H-bridge and transformer. Your supply must provide 13 A continuous (more or less).

In the middle area is a flyback topology. Your supply must provide 26 A for a fifty percent duty cycle.
 

Compare to a flyback, the bridge will have larger Mosfet losses, but much better magnetics and diode utilization.

Unless you have a very good understanding of magnetic design, is easier to reduce Mosfet losses than transformer losses, so I would go for the bridge.

Another topology that could work is the push-pull, just be aware of staircase saturation.
 

Which will be more efficient ? Flyback or H-Bridge?

I think Half-Bridge will be more efficient.
Click to expand...

H-bridge is different from half-bridge.

A half-bridge has two switching devices stacked (like a totem pole). A synchronous converter would contain a half-bridge. In some cases this improves efficiency over an asynchronous converter.

I should have said "full H-bridge". It contains four switching devices. It is the simplest way to turn DC into bipolar AC.
 

I made a push-pull type converter. it was working good. But I got a problem, after running for few min, the converter consumes more current. and this self consuming current increases... What is this for? But if the converter is loaded by some lamps, it works fine. problem is its self consuming current.
 

Step 1: Pretend you want to buy one today. Pull the datasheets
for anything you can find that looks like it does the job. Follow
the clues re topology, magnetics, power switches and control.
 

Actually this design will be used in solar micro-inverter. So efficiency must be over 90%. I tried push-pull type converter, flyback converter and boost converter. None of them can get over 80% efficiency. What type of converter I can use for this purpose?

System ratings will be:
Input: 10V-25V DC.
Output: 125-240V DC.
Efficiency: >/= 90%.
 

Your description is too vague to identify a specific reason for low efficiency. Presently we can just say: You didn't manage to make it right.

For a 1:10 step-up ratio, a coupled inductor (transformer) based solution promises higher efficiency than a singke inductor (e.g. boost converter) circuit.
 

Output current= ?
Switching Frequency = ?
Type of controller used = ?
Characteristics of magnetic devices = ?
 

Most topologies could probably fulfill that spec (well not flyback), your results will likely just be a function of the component selection and layout. If it were me I would probably just try for a boost converter first, or a push-pull if I want isolation.
 

What is the actual output current?

Although 39 Khz is a relatively slow frequency, which will allow you to get by with inexpensive magnetic components, you may reduce losses by going to improved materials and winding techniques.
 

Congratulations!

Is that efficiency at maximum load and minimum input voltage?
 

I tested with loads, 3W, 6W, 15W, 32W. and input voltage 11.6V, 12V, 13.5V and 14V. 96% is the average most obtained efficiency among all these test result.
 

Mithun_K_Das said:
I tested with loads, 3W, 6W, 15W, 32W. and input voltage 11.6V, 12V, 13.5V and 14V. 96% is the average most obtained efficiency among all these test result.
Click to expand...

I've got a different application where I need very high step-up voltages but at low current. Do you have a reference schematic for your solution?
 

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