A Novel Hybrid Modulation Strategy of LCC Resonant Converter with Capacitive Load

With LCC resonant circuit as the topological high- voltage charging power supply, the commonly used modulation methods are pulse-frequency modulation (PSM) and phase shift modulation (PFM). Aiming at the problem of wide frequency modulation range, low utilization of magnetic parts when PFM, and narrow soft switching range when PSM, a functional relationship between output current and switching frequency is established, and a PSM-PFM hybrid modulation strategy is proposed based on the output current characteristics. This control strategy uses PSM at light load to increase the charging speed of the capacitor without increasing the switching current stress, expand the soft switching range, and use PFM at heavy load to narrow the frequency modulation range. The feasibility of the control strategy was verified by building a simulation and experiment platform. The charging speed is doubled, and the frequency range is reduced to a quarter of the original.