Research on Small Signal of Charge Control LLC Converter

This paper develops a half-bridge LLC converter based on charge control and uses a new enhanced method to derive the transfer function. Charge control has become the most popular control method for the LLC converter in recent years because of its easy compensation and fast dynamic response. Its small-signal model has only one pole before the switching frequency if assuming that the input power equals the output power. But this conventional approach oversimplifies the charge control system, which will cause errors from 1/10 switching frequency to switching frequency. An enhanced small-signal method for charge-controlled LLC converter is used, which is more accurate than conventional method. The simulation results in PSIM and SIMPLIS verify its advantages.