LLC resonant wireless charger feedback problem

[cetintas]

Hello everyone, I am currently designing an LLC resonant converter for my graduation project. I use FAN7631 as frequency control IC. In application, voltage feedback is taken from secondary with an optocoupler. But, result of primary and secondary are seperated I can't use an optocoupler system for closed loop. I can't figure out and couldn't find any solution for that. I will be appreciate if you help me to make it closed loop. I consider to use auxilary winding but I don't know how to use it.

[Manul]

Is closed loop a must? I mean you MUST do it? Ok, then one thing that comes to my mind is to sense a voltage on a secondary side and use some kind of load modulation. That load modulation can be sensed on the primary, decoded and used as feedback.

But that might become complex to get right.

[Manul]

Found this:

https://www.analog.com/en/technical-articles/close-the-loop-between-wireless-charger-receiver-and-transmitter.html