A high-power-factor electrical ballast for HID lamp requires 6 switching devices. The cost ratio of switching devices and its driving circuits in electrical ballast is not small.
Therefore, this paper proposes a new switching method for a ballst which uses 4 switching devices. In experimental results, the proposed method obtains the power factor 0.990 with output power 400[W]. This paper verified that the proposed method has the fine driving performance on a high power HID lamp.