Discrepancy between MOSFET module input capacitance and total gate charge

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SiCEngineer

Joined May 22, 2019
444
Can you post a diagram of exactly how you are measuring the current in your circuit?

im away from lab now but there’s not much to it. Originally I was just reading the input current on the bench top power supply, but then I inserted the DMM in series with my bench top and between the positive input of my isolated gate driver power supply.

The D.C. level reads twice as much as the AC level - and thinking about it this makes complete sense as my duty cycle is 50%. Therefore the power supply is drawing the D.C. current when on and nothing when off at whatever frequency I choose. The AC should be half that of the DC. I had assumed that my bench top supply would Measure the average input current - but it seemingly does not.

Looks like that’s why all of my power measurements were twice as large than dictated by the equations!
 
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