Need help clipping high power AC current for both top and bottom of wave

I need to ensure the peaks of a high (40 amps or so) current AC input are below a value set by zener diodes. I can't use just zener diodes to do this since current is so high. So, I used zeners to trigger MOSFETS, and the MOSFETS do the heavy current handling. I made 2 circuits, one to clip the top with an N channel MOSFET, and one circuit to clip the bottom with P channel MOSFET, then put the two circuits together in series. Is there a better way to do this?

by gsorter
August 31, 2022

A simple, but rather expensive, circuit, with 2 Zener. You need 5W components though and, while Jameco doesn't have in stock, I found the 40V -5W Zener diode to be around the 50$ mark, each.

Click on the Simulate button, for a time domain simulation, and you could see that indeed, it is clipped at 40V (and with the current, you can double check the power to be dissipate).

Not very energy friendly.

Why you don't try to step down the AC with a transfo, or other more energetic friendly solution? Or what criteria could we chose to better define .. better, in this context?


by vanderghast
September 01, 2022

I thought about your circuit, but I may need to dump almost 1000 watts through those Zeners, and they would blow up. I can't use a large transformer because this will be on a drone, so weight is very critical. This will be to convert 3 phase AC from a 5KW generator into DC, so currents will be on order of 100 amps at a voltage of about 50 v. This power will be connected in parallel with a battery bank, and the clipping is to prevent too high voltages from going to the batteries. I hope to clip each leg of the 3 phase with 3 of these or similar circuits before going to a diode rectifier

by gsorter
September 01, 2022

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