# Hybrid Full bridge/Half bridge DC/DC Converter topology?

Thread Starter

#### JimmyCad

Joined Jul 1, 2019
6
Hello,

I have came across a DC/DC converter topology used in high voltage applications. However I am struggling to understand what is happening in the circuit. I will attach an image of the converter in question. It outlines that it is a full bridge/half bridge topology.

I have seen both the half bridge and full bridge variants of the LCC converter, of which I am familiar with. However, the way this circuit is configured is quite confusing for me. I can only possibly think that the configuration is:

Two parallel half bridge LCC converters, each feeding a primary winding of the transformer. The only reason I can see this being beneficial is because the HB converter typically presents the transformer input with half of the input voltage - maybe using two allows the full input voltage to be given, thus removing this drawback of the HB in comparison to the FB inverter which presents full voltage, which obviously is good for HV because the step up ratio is less in the FB variation. But I am fully confused by why it is labelled as a half-bridge/full-bridge converter - it can't be both, can it?

Thanks in advance!
Jim

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#### shortbus

Joined Sep 30, 2009
7,760
labelled as a half-bridge/full-bridge converter
All 'full bridges' are made up of two 'half bridges'.

Thread Starter

#### JimmyCad

Joined Jul 1, 2019
6
All 'full bridges' are made up of two 'half bridges'.
I understand that, but what I mean is are these two half bridges connected in parallel each to a primary winding of the transformer? In a full bridge, it is obvioulsy composed of two half bridge legs, but only one primary winding is typically used.

#### shortbus

Joined Sep 30, 2009
7,760
That isn't how I see your image. To me it looks like one half bridge would be high while the other is low, and then the switch positions. This is quite common when trying to simulate AC with a DC voltage, and allows the "bootstrap capacitors" to charge on the half bridge drivers. But also beware that even though they show it driving a transformer it isn't going to -1. make real AC on the secondary, or, 2. make the transformer very happy.

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