Looking for a suitable DC -DC buck conveter using coupled inductor /reactor

Thread Starter

Hasan2019

Joined Sep 5, 2019
21
Hello there,

Anser this post who knows Power Electronics well.

Take a look my buck conveter in attachment.
People may called it "Dropper'
rsz_old_idea (1).jpg




It has following properties,

1. Input is 120 to 160 volt DC/ 30 Amp.
2. Output must be 110volt/30 amp(maximum). +- 5% regulation( contineous output should be 20 amps)
3. Isolated in both input and output circuit.

4. Shunt sensing.

5. proper feedback.

6. 2 switches gets OFF/ON alternately.

7. May be soft switching.

8. May be 90% efficient.


I am thinking to modify it because bulky reactor/coupled inductor.
It has high current application.

kindly suggest a design that has

1. Less switching losss.
2. Less stress on switch.
3. Less number of component.
4. ZVS or ZCS idea.
5. Suitable ripple minimization.
6. Suitable couple inductor design.
 

MrAl

Joined Jun 17, 2014
7,761
Hello,

What do you mean by "isolated in both input and output circuit".
Simple buck circuits do not offer galvanic isolation so you will have to explain.
 

RPLaJeunesse

Joined Jul 29, 2018
109
That "2 switches gets OFF/ON alternately." sounds like a problem to me. Perhaps you should have them in a totem-pole (push-pull) configuration. Your circuit would probably work with a single inductor, as that is all that is needed for a buck regulator.
 

MrAl

Joined Jun 17, 2014
7,761
That "2 switches gets OFF/ON alternately." sounds like a problem to me. Perhaps you should have them in a totem-pole (push-pull) configuration. Your circuit would probably work with a single inductor, as that is all that is needed for a buck regulator.
Hi,

It looks to me that he is going for a dual switch buck so it is like two bucks in parallel. That has some advantages.
 

RPLaJeunesse

Joined Jul 29, 2018
109
Hi,

It looks to me that he is going for a dual switch buck so it is like two bucks in parallel. That has some advantages.
You may be correct but if that is the case then the statement "2 switches gets OFF/ON alternately" is incorrect. They would likely be driven 180 degrees out of phase but they will overlap some, they do not "alternate".
 

Thread Starter

Hasan2019

Joined Sep 5, 2019
21
Simple buck circuits do not offer galvanic isolation so you will have to explain.
Since its high current/ voltage application, I think isolation is necessary. As usally people do with some transformer and optocoupler.
I have not post the whole controle diagram.

Perhaps you should have them in a totem-pole (push-pull) configuration. Your circuit would probably work with a single inductor, as that is all that is needed for a buck regulator.
Yeap make sense!

Mr.Al and RP thank you both !

Thanks a lot to recognize it.
We can raised " Phase" in DC-DC buck action in terms of switch action.
Multiphase but not interleave?

Looking at this circuit it seems like a 2 conventional buck converter working at a time or alternately ! Need to analyze both DCM and CCM mode for the inductor. If its not coupled inductor that means 2 inductors are not magnitically coupled!
Can you see any " transformer" action on it?

As its output and input currents are same, then yes ! Voltage should be control.

Interesting to see its ON and OFF circuit. What would be the charging and discharging path in this circuit?No freewhiling action? 2 capacitors are helping charging or discharging through to load?

Input power isolation has done with some transformer and optocoupler.

Output can monitoring can be by shunt sensing.
Couple inductor is more cost effective but high current and voltage need to be carefully solve. High current IGBT is only solution?

For HVDC application people use many IGBT in sequence !
 
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