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Suggestions for high voltage floating Hbridge overcurrent protection (solved)

Thread starter #1
Hello all, I am looking for a way to add over current protection to the enclosed H-bridge. The current signal needs to be galvanically isolated as the controlling MCU is on the grounded side of the isolation barrier but the H-bridge is grid side.
I have thought of an opto-coupler with sense resistor but this is power hungry, I would like to use a current transformer but the current waveform is uni-polar (see enclosed plot) so would this still work or can it be made to ?
I should mention the current waveform is both continuous and discontinuous and the H-bridge only switches at 50hZ (it is an unfolder) but the current frequency it passes is 50Khz.

EDIT Solution
Just in case its useful to others I realize I had solved this before in another design using a LEM HLSR active transformer that deals with unipolar currents very well and does not have the high emi susceptibility of some of the smaller alternatives I had also tried.


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