This work presents the mathematical analysis and controller operation of the AC-link dc-dc converter, a parallel resonant converter, for which state plane trajectory control (SPTC) is proposed. The contribution is a simple, autonomous control technique achieving the benefits of bidirectional power flow, soft switching, and converter switching at its natural resonant frequency as opposed to conventional forced control operations. The switching sequence is implemented using an autonomous state machine triggered by the voltage and current state variables of the resonant LC tank, transitioning between modes of operation strategically to achieve said benefits. All results were simulated in MATLAB/Simulink utilizing the PLECS blockset.

Power electronic conversion units will serve as a key enabling technology for assisting in the continued growth of grid-scale energy storage. This paper presents existing and future power electronic conversion systems and components that aid the interconnection of grid-scale energy storage or utilize storage to minimize grid disruption at all voltage classes including transmission, distribution, and future grid architectures such as the microgrid. New R&D solutions to aid the interconnection process including efforts in bidirectional charger design and potentially solid-state transformers (SSTs) are emphasized. The role of energy storage to support microgrid research and growth, while highlighting power electronic behavior within this environment, is considered. Last, an example that bridges the microgrid and energy storage theme is given through the design and operation of a direct current (dc) electric vehicle (battery) charging station. When appropriate, manufacturer solutions and success stories of utilizing latest battery technologies interfaced via power electronic solutions at the utility scale are provided.