Research on Full-Bridge LLC Resonant Circuit under Compound Control of Input Compensation

In the electronic ballast of ultraviolet lamps designed with full-bridge LLC as the main topology, the transformer winding feedback circuit is usually used, and the output high-frequency voltage of kilovolt level is reduced and rectified as the sampling voltage of the electronic ballast. Combined with the traditional single-voltage closed-loop PI control mode, the electronic ballast can control the output voltage of the feedback winding of the electronic ballast to ensure that the electronic ballast can output stable voltage to drive the ultraviolet lamps. However, the engineering application shows that the output voltage of electronic ballast under this control mode, that is, the output voltage of full-bridge LLC circuit, has a slow dynamic response, which needs to be further improved. In order to speed up the dynamic response of full-bridge LLC resonant converter, a control strategy based on the combination of single voltage loop PI control and input compensation compound control is proposed. The simulation results show that the proposed control strategy combining single voltage loop PI control with input compensation compound control can effectively improve the dynamic response speed of the output voltage of full-bridge LLC resonant circuit.