Measuring the Output Impedance of a (Large Capacity) Voltage Source

Anand P. Paralkar · 2013-12-29T09:55:44+00:00

Hi everyone, I am trying to test a MOSFET H-bridge at around 400V DC input. I need to observe the MOSFET Drain-Source waveforms for ringing during the on to off state (and vice versa) switching. I observe that the drain to source waveform is affected by the DC source that I use to supply in the input DC voltage to the MOSFET H-bridge. We have three different sources (including one that I built using a simple variac, rectifier and huge capacitor bank) and I feel that there is a particular DC source (bought from a vendor) that does not work well (gives horrible drain to source waveforms). In order to be sure, I would like to see that the one that gives a bad waveform has something in its output impedance that makes it misbehave while the other two have something "good" about their output impedance that make them give good switching waveforms. Is there a (simple) method to measure the output impedance of a 600V, 15A DC voltage source? I will use the suggested method to evaluate the three sources that I have and hopefully, I will find the evidence to prove that the source that gives the bad waveforms has something "bad" in its output impedance. :) Regards, Anand

Dec 29, 2013 41 Replies

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John Fields 12 years ago

Ah, now I see... The problem is either that English isn't your first language or that your comprehesion and composition skills are flawed to the point where you're - more often than not - unintelligible.

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John Fields 12 years ago

If you need Tc of the transistor package to stay at

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