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Dennis Feucht

# Seemingly Simple Circuits, Part 6: The Refined Current-Loop Converter Model

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D Feucht
6/29/2015 5:41:06 PM
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Re: help regarding flyback current mode design
Nishant,

Before inundating me with CAD details, would you please

1. Describe your circuit;

2. Explain the problem you are having with it.

You can reach me via email through innovatia-dot-com.

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nipan
6/29/2015 7:31:41 AM
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help regarding flyback current mode design
Hello Dennis,

would it be feasible if I could consult you on a flyback current mode control design I am doing for an automotive application?

If your time permits I could share the mathcad design file for your perusal.

Regards,

Nishant.

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D Feucht
3/18/2015 7:27:58 PM
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Re: Average current
Peak current is more closely related to power transfer in converters operating in DCM. Peak-current control is, of course, used in DCM flybacks, for instance, but in the series which this article finishes, operation deep into CCM is assumed all along. "Deep CCM" is a characterization of the kind of waveform that that has a large static (dc) component and small ripple (ac).

In this case, what determines power transfer is the average or static current value times the Delta current ripple. What is advantageous about CCM is that not only does the ripple size determine transfer power, but the average primary current does too. That means much power can be transferred with little ripple (and noise).

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etnapowers
3/18/2015 10:00:29 AM
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Re: Average current
@Dennis, I agree with you on the importance of average values in the dimensioning of a current loop model, I add that also the peak current plays a role for example to evaluate the charge that is transferred in a cycle of switching to the output capacitance of the converter.

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D Feucht
3/17/2015 7:04:51 PM
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Re: Average current
You'll have to explain to me what "dimensioning steps" are.

In the derivations, peak and valley values occur frequently. The main point is that the loop dynamics for the valley current is not the same as for the average current, and it is the response of the average that is usually of interest. The valley point dynamics tell us what is happening at one point in time each cycle. The average tells us something about the response over the entire cycle and is a (piecewise-) continuous measure of the dynamics.

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etnapowers
3/17/2015 11:32:57 AM
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Average current
"This is significant because the current of interest to us in power supply design is the average current. Power-supply ratings are based on it."

Right, but I would add many dimensioning steps have to be performed taking into consideration the maximum value of current. Do you agree Dennis?

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