Simple half bridge not working in LT Spice

[si2030]

Hi there,

I am having some real issues with a simulation of a basic half bridge bare bones SMPS design.

I wanted to try and understand how a half bridge works and so I used a schematic that I based my LT spice design on... here it is.

View attachment 61751

this is a screen shot of the circuit with the traces.

View attachment 61752

I have also included the actual LT files if someone would like to run it...



First of all its suppose to put out 35 volts... from the net labelled OUT. it doesn't do that.

Second, I am unsure if I have the ground in the right place (on the right side of the power transformer.

Third, when I attached the bridge rectifier the ripple was obscene... there is no load on it... so it should not even budge once the filter caps are full... I would have thought.


Wondering if someone might take a look and tell me why it (a) it doesn't work and then (b) tell me how its suppose to work - the half bridge that is...

Kind Regards

Simon

 

[alec_t]

For starters, V6 is upside down. Either invert it or change its value to +320.
I think you also need to reverse either L2 or L3, and L4 or L5.

 

[ronsimpson]

The circuit you got from Taylor is not what you built in spice!
There is a point that connects to C2, C3, R2, R4 and L1. This point should not be connected to ground! It can not connect to C4, C7! C4,C7 can connect to ground.
There needs to be A.C. on the left side of the transformer.

 

[ronsimpson]

For starters, V6 is upside down. Either invert it or change its value to +320.

I think V6 is fine. Not the way I would have done it. Not he way Alec_t likes it. It seems to work fine.

 

[alec_t]

Yup, you're right about V6. Knickers in a twist .

 

[ronsimpson]

Yup, you're right about V6. Knickers in a twist .

It took a second to understand the inverse of a negative number.