Hello,
I want to design an Buck Convertor for my application which require 18v to 40v Input_19v to 30v Output at 30 Amps,The Basic Need of this supply is to Charge Battery and provide power to a load System simultaneously.

1) I am using an 20 Amp 0-24v Transformer.
2) Buck Convertor O/P is controlled via MCU With User Data Input.
3)Short Circuit Protection.
4)Current Limiting.

 

18v to 40v Input_19v to 30v Output at 30 Amps

You can't get more voltage out of a buck converter than the input voltage.
If you want more volgage you will need to use a buck-boost converter.

1) I am using an 20 Amp 0-24v Transformer.

A transformer RMS current rating needs to be derated about 60% for the DC output of a rectifier-capacitor filter, thus the maximum current into the converter will be about 12Adc.

The maximum output DC voltage of that transformer using a full-wave bridge will be about 30V, so that will also be the maximum output from a buck converter.

 

Yes you are correct on the input Voltage part,Buck with work with higher voltage to output lower voltages.so I need to design an buck boost convertor for my purpose.
https://m.tomtop.com/p-e2067.html?c..._3eGuF8-WgqvWcZH3gBxJk4Cdtgvg5YaAswyEALw_wcBq
What are your suggestion on this ?

 

Why do you need a 19 to 30V out if you are charging a battery?
What is your battery type? What sort of battery protection will it need? There are a lot of details missing from your request.
Is this a UPS? and what is the final load requirements?

 

There are some problem in the specs,I need 22v to 28v Supply with a total Current limit of 20 A Continuous.
And the Battery is Feeding Power into load continuously during charging of battery in parallel.

 

Basically, is this a 24V lead/acid battery charger?
The battery chemistry is important to know as the wrong supply can kill the battery.
There are lots of high current 24V battery chargers available on places like Aliexpress and Ebay. Have you looked there?

 

There are some problem in the specs,I need 22v to 28v Supply with a total Current limit of 20 A Continuous.
And the Battery is Feeding Power into load continuously during charging of battery in parallel.

What is the voltage of the battery?

 

12v batteries connected in series.And they are rated at 80 Ah each, Battery chemistry is Lead acid.

 

And I also Want to know if it is possible to use PWM based power stage to charge the system.

 

Lead acid needs Constant Voltage to charge them, so a 12V battery needs 13.8V to charge it.

 

Don't see why you want to build a battery charger that's readily available to buy?

 

The Problem with SCR Based Chargers is the Continues Current Spikes generated at the Output End of the Charger Which some times create a problem with the Electronics connected as load on the other side of the battery.

 

The critical component required for this design will be the inductor. As the current requirements in the inductor go up, the design becomes more and more challenging. There is a tug of war between the wire guage and the number of turns on the core. There there is the matter of core saturation. AFAIK your design will require a greater than average design effort by someone who really knows what they are doing when it comes to component selection and PCB layout. You can't skimp on this stuff.