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Ground capacitance measurment for Isolation monitoring device
Posted: Mon Mar 31, 2025 5:57 am
by kavirunimsith
I am designing an Insulation Monitoring Device for an electric vehicle. The battery voltage of the EV can go up to 1000V. I want to measure the ground capacitance of the electric vehicle to mitigate its effect in isolation monitoring. What method should I use to do this on the IMD PCB? Will AC current injection cause complexities? Can anyone suggest a method or a white paper/reference that I can use?
Re: Ground capacitance measurment for Isolation monitoring device
Posted: Mon Mar 31, 2025 6:41 am
by uhi22
There is an interesting description of isolation monitoring from TI.
https://www.ti.com/document-viewer/lit/html/SSZTCY5
From my point of view, calculating the capacitance is just a matter of software. When you close one of the switches, you will see an inrush-curve. At the end of the curve you can calculate the resistance, and the slope of the curve allows to calculate the capacitance.