Hi all,

I have implemented a WPT system with communication in both ways using ASK. When I connected communication part on RX side the same way as on TX, there just was not enough amplitude change to be detectable on TX side. So I made communication part using two mosfet and capacitor. That was working well until one of mosfet failed (event that triggered failure was adding load on RX side) causing mosfet driver to also fail (measuring, mosfet is now "short circuit" between S-D-G; mosfet driver is "always on" and getting hot). Used mosfet is IRF100B201, mosfet driver used is MCP1416. Coil Vpp on RX side is 60V when on full load while 45V on "open circuit" (running only microcontroller using 0.03A). Mosfet driver IN is connected to microcontroller PIN that gives 5V while Vdd of mosfet driver is 12V. Why this failed? D-S voltage and G-S voltage were not violated... Can mosfets be used in this way?
Thanks for every opinion while I am really out of ideas what might have happened.

Gabrijel

 

Looks like I have found answer to my own question I have tested 12V regulator output on RX side while sudden change in load. The image in attachment says everything: there are "spikes" over 20V (positive and negative) while mosfet can withstand only 20V on G-S. So it looks like that "killed" my mosfet and driver. I'll check if I can change something on 12V regulator or I'll just add zener diode for protection. I found this as a logical explanation and solution. But, as more heads are always clever than one alone, I am open for any suggestion Thanks!