Improved Dynamic Behavior for the Series-Resonant Converter Using Bidirectional Charge Control

A new control method for the bidirectional series-resonant converter is presented that optimizes dynamic behaviour. The series-resonant converter is a frequently used converter type due to its inherent zero-voltage switching property for switching frequencies above the resonance frequency. However, a method to control the series-resonant converter dynamically while facilitating bidirectional power flow and zero-voltage switching of all switches is not yet presented. This paper presents bidirectional charge control, a control method that realizes dynamic, bidirectional operation of the series-resonant converter. It targets a net amount of charge displacement through the controlled port between two consecutive zero-current crossings, by describing all switching events as a function of the charge difference across the resonant capacitor. As a result, bidirectional charge control facilitates ZVS operation of all switches, regardless of the operating conditions, while minimizing the \textcolor{blue}{reactive currents through the connected voltage sources}. This paper describes both the theoretical analysis regarding bidirectional charge control as well as an experimental verification including non-idealities and the corresponding implementation to guarantee the desired control of the series-resonant converter. Bidirectional charge control realizes dynamic, bidirectional operation of the series-resonant converter while guaranteeing zero-voltage switching of all switches.