LTSPICE SIMULATION FOR A BUCK CONVERTER

Hello guys,

I am trying to simulate a multi-input buck converter, but I am not getting the desired output voltage. I am new to LT SPICE, can someone help me to detect the fault in the circuit?

Thanks

ASHO said:

Hello guys,

I am trying to simulate a multi-input buck converter, but I am not getting the desired output voltage. I am new to LT SPICE, can someone help me to detect the fault in the circuit?

Thanks

Click to expand...

upload the .asc file and any special .sub circuits you used in your schematic.

Hi Mike,

I am simulating a multi-input back converter for generating a 24v voltage packet. There is a complete paper related with it, but right now I am just uploading the file & another photo for the voltage waveform which I was expecting. Can you please have a look on the circuit. Thanks

A buck converter needs an input voltage higher than the output voltage, so 12V and 15V inputs aren't appropriate for that. Those sources would be usable in a boost converter.

Try this one. I made changes to make it easier to see when the switches are open/closed. I modeled the switches a bit more realistically. I think there is a missing diode.

if you want to know more about LTspice and buck converters, my website might help:
http://www.simonbramble.co.uk/

MikeMl said:

Try this one. I made changes to make it easier to see when the switches are open/closed. I modeled the switches a bit more realistically. I think there is a missing diode.

Click to expand...

Hi Mike, Thanks for the additions. It is working more better than my model. I have a paper, according to the paper, this circuit can create a 24V power packet. The diagram of the power packet can be seen in the paper attached, can you please have a look and tell me that this packet can be made from this circuit? Please have a look on 24v payload generation paragraph. I will be thank ful to you... .

The circuit only implements a single switching cycle. At the least, you'll need to specify a period for the pulse generators if you want them to run continuously.

You're going to either need to implement some sort of controller or at least start start by calculating the average inductor current and duty cycles necessary for a presumed steady state load. As it is, the V1 on time is too long; watch inductor current in the first cycle. The converter is also operating in discontinuous mode despite a significant load, so the output voltage swing is huge. I'd say start design calculations as if this were a 36v buck converter, and then work in how much of the on-time can be shared by the 12v source.