State Trajectory Control of Startup for LCC Resonant Converters With Capacitive Output Filter

LCC resonant converters have been widely adopted in pulse-modulated high-voltage generators to achieve high power density and high efficiency, which require a short rising time of output voltage. However, if the LCC resonant converter starts up too fast, the voltage and/or current stresses of the resonant tank during startup may be several times higher than those of the steady state due to the complex dynamic behavior of the resonant tank. In this article, a simplified state model of LCC resonant converters is first introduced. Then, optimal state trajectory control (OTC) is proposed to optimize the startup performance of LCC converters. Besides, to combine the advantages of OTC in the startup and power integrity (PI) control in the steady state, hybrid control is adopted. Finally, an LCC resonant converter prototype is constructed to verify the proposed OTC, which achieves a minimal rising time of output voltage with no additional current and/or voltage stresses in the resonant tank during startup compared to the conventional control.