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[SOLVED] High input voltage buck converter (156Vin-36V,10A out) Non isolated

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ats2

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Hello,
I want to design a buck converter using 156Volts input and 36V output,10A, non isolated. The input voltage is little bit high to use step down controller like LTC7810-140Vin.
Is there any efficient way to step down 156Vdc below 140V or directly convert to 36V?
Or is it reliable using current mode PWM controller below? (Designed by forum member "treez",I have never used before)
lt1243.PNG

Regards.
 

yes there are lots of ways to do this, including pulse transformer drive of high side mosfet or lever shifter gate drive IC or discrete solution
 

Simulation showing typical waveforms you can expect.

Duty cycle is controlled by an ordinary logic gate. It biases an NPN which biases a PNP.

buck converter contr by inv-gate NPN PNP 156VDC to 36V 10A.png

Notice to obtain your spec 10A, inductor saturation rating needs to be greater than 10A. Upwards of 20A.


Smoothing capacitor must carry 5A back and forth at several kHz.

By interleaving two or more converters you can reduce stress on all components.
 
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Hi,

Or use one of the simple ACDC flyback chips .. they usually give isolated output, but you are free to connect both sides and omit the feedback optocoupler.

Klaus
 

Thanks for answer. You mean, using flyback chip in buck topology, or Designing a flyback with transformer without opto?
I try to solve it without transformer (Custom transformer design issues and it would be very large for 36V,10A(360W))

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Thanks for answer. I wonder the control part actually, can you offer ic for PWM control or gate drive?
Regards,
 

ats2 said:
Thanks for answer. You mean, using flyback chip in buck topology, or Designing a flyback with transformer without opto?
I try to solve it without transformer (Custom transformer design issues and it would be very large for 36V,10A(360W))

- - - Updated - - -

Thanks for answer. I wonder the control part actually, can you offer ic for PWM control or gate drive?
Regards,
Click to expand...

The input voltage is 156V. It may have serious safety issues if you use a non-isolated topology . Try using a forward or flyback(The core will be bigger)
 

Hi,

You mean, using flyback chip in buck topology, or Designing a flyback with transformer without opto?
Click to expand...
Yes, this was the idea. Don't know if it fits your requirement.
I think there are many ready to buy parts available.

There are even ready to buy power supplies with 36V/10A output for 90...132V AC input on ebay.
I expect them to operate on 156V DC input. No guarantee. Maybe worth a test.

Klaus
 
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single flyback for 36V 10A can be problematic ... due to size of current peaks - rms in transformer ...
 

Thank you, simulated using ltc3803, looks no problem.
Capture.PNG
For high side current measurement, I plan to use LT6375, I hope it is good idea :)
Regards.
 

how are you going to dive the gates of the N fets to 12V above Vin ... ?
 

Hi, by using fan7171 gate driver (bootstrap) and bottom side is diode.
 

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