Dual Active Bridge: Function Principle

[Leitz83]

Hi everyone,

I am studying the function principle of a dual active bridge (DAB) dc-dc converter. What I don't understand is why the dc component of the inductor current is always zero in steady state (or at least, this is what all the papers I read up to now are showing). In my simulation the dc component of the inductor current is not zero although the steady state is reached.

Looking forward to your answers.


Best Regards, Leitz83

 

[atripathi]

Can you share picture of your schematic/circuit?

 

[mtwieg]

Can you share picture of your schematic/circuit?

It's described pretty well in here:
**broken link removed**

There should be zero inductor current at steady state due to the fact that the volt-time product applied to both the primary and secondary should always average to zero. This condition will prevent DC current from appearing. However it will not always cause existing DC current to converge back to zero. That would have to be enforced by the control circuit, or by adding some DC resistance to the primary/secondary paths.

Are you doing transient simulations? If so it may be just an initial condition thing.

 

[Leitz83]

Thanks for your answers!

I have already speculated, that the dc component has to be forced to zero somehow. So this has to be accomplished by the control circuit.

Yes, I am doing transient simulations with SimPowerSystems but I cannnot set the inductor current to an initial value, because SPS prevents this.

Thanks a lot!

Regards, Leitz83