Multimode Constant Power Control Strategy for LCC Resonant Capacitor Charging Power Supply Based on State Plane Analysis

Abstract

A novel constant power charging strategy is proposed for LCC resonant capacitor charging power supply (CCPS) in this article, which combines the advantages of discontinuous current mode (DCM) and continuous current mode (CCM) to increase the charging speed of capacitor and the utilization of input grid capacity. In order to implement the multimode constant power control (CPC) strategy, a steady-state model of LCC series-parallel resonant converter is built by state plane analysis, and the analytical expressions for output voltage, average output current, and switching frequency are derived. By the analytical expressions, this control strategy directly determines the relationship of the output voltage and the switch frequency, so the frequency control curve of the pulse frequency modulation could be realized easily. Accordingly, the converter operating along the control curve can take advantage of high average and low peak current of CCM, small switching loss of DCM. Finally, the accuracy of LCC state plane model and the effectiveness of multimode CPC are verified by the simulation and a 2-kW CCPS experiment.