Current mode control for LLC series resonant dc-to-dc converters

Conventional voltage mode control only offers limited performance for LLC series resonant dc-to-dc converters experiencing wide variations in operating conditions. This paper presents current mode control which could consistently provide good closed-loop performance for LLC resonant converters for the entire operational range. The proposed control scheme employs an additional feedback from the current of the resonant tank network to overcome the limitation of the existing voltage mode control. The superiority of the proposed current mode control over the conventional voltage mode control is verified using an experimental 150 W LLC series resonant dc-to-dc converter.