Low Cost Electronic Ballast with Buck Converter as PFC Stage

In this paper, a low cost buck converter was selected as the PFC stage of the electronic ballast for a 70W metal halide lamp. In this way, several advantages could be obtained, such as simple circuit topology, easy control strategy, especially decreased cost and low requirements for circuit components. All circuit parameters should be designed to ensure that the buck converter was operated in DCM. This paper presented the design of both the main circuit and control loop, analyzed the stability of buck converter, and discussed the function of PFC stage. Finally, the results of both simulation and experiment were given to testify the effectiveness of PFC.