Does the critical conduction mode flyback have the RHP Zero trouble?

Thread Starter


Joined May 22, 2019
I suppose the title describes this subject perfectly without an explanation.
I currently have a two switch flyback converter for my PhD project designed but I am thinking of changing this to the active clamp flyback to make use of a half bridge evaluation board that I have in my lab to save some time on PCB design.
I like the two switch because I was able to operate it in DCM. This is because the converter must be able to regulate the voltage at the output with a pulsed load which varies in frequency with good precision. And little overshoot. The problem I have with the active clamp flyback is that it has a RHP Zero which would be difficult to compensate and the performance I need may not be met properly. I was wondering whether the ACF can be operated in discontinuous conduction mode? Also, if we operate it in critical conduction mode, can we avoid the RHP Also?
I think if I monitored the transformer current and the switch voltage, I may be able to control the main switch and auxiliary clamp switch quite tightly to switch on the zero current crossing point of the current or on the valley of the switch voltage, to provide accurate control of the output voltage. This all depends on the removal of the RHP zero of course.
Any thoughts are appreciated.