Incorrect turns ratio??? and inductor current in DAB model file....

Question

Hi

I am working on the DAB thermal model (demo file) and it seems to have little mistake as per my understanding, where in the parameters initialization  turns ratio, n = 4 but it should be n = 1/4 as, n_pri = 4; n_sec = 16.

It is confusing. And this one thing is messing around with my calculations for this DAB.

I am trying to find the inductor current and it does not match with the model file. I am using the model parameters (V1 = 95 V, V2 = 380 V, fs = 252e3, L = 2.052e-6, N1 = 4, N2 = 16) following equations to calculate the current at point A and B, screenshot attached: 

 

Whether I use n=4 or n = 1/4, I do not get the desired inductor current as in the graphs.

Am I correct in my approach? Can someone please help? Screenshots are attached.

Thanks

Sneha

Answer 1

Hi Sneha,

As I have responded to you before under the comments of a different thread here, 'n' here is the turns ratio w.r.t the secondary side. For example, in the electrical transformer you can choose '1' as your number of turns on the primary side and 'n' as your number of turns on the secondary side.

Irrespective of what 'n' stands for in the model, since the number of turns of the primary and secondary are clearly mentioned, that should help you calculate the turns ratio and avoid any confusion.

Have you checked out the link referenced in the DAB demo model description? The answer you are looking for about the inductor currents can be found on page 20 of reference [1].

Regards,
Manu

Comments

Thanks for your answer manu.

I am using the primary and secondary turns ratio to avoid any confusion with 'n'.

Yes, I have gone through the reference 1 and the inductor currents mentioned on page 20. These equations do not answer what I am looking for. But I have found other references now, which are more useful in understanding the concept.

Thanks

Sneha

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Sneha,

That's great! Also, keep in mind that in those equations on page 20, 'T' is the half cycle period  and 'd' is the phase shift.

The phase shift is denoted as 'm' in the model. You can find it by opening the subsystem "Phase Shift Controller", and using a scope at the output of the discrete transfer function block.

Regards,
Manu