Gain plot of open loop never crosses 0 dB

Thread Starter


Joined Sep 12, 2020
Below is the open loop output current to control plot for a CLLC resonant converter(obtained using AC sweep in PSIM) . As you can see the gain curve never crosses the 0 dB line and the phase margin is inf, hence the open loop system is always stable.
Note: switching frequency is around 200kHz, and the resonant frequency is 300kHz.
My question:
  1. Can we use a simple P controller in a closed loop as the OL system is theoretically stable?
  2. Why do we need DC gain in this case? (a friend suggested using a PI controller to give High DC gain)


Please, let me know if you need any other information, Thanks in Advance.