Modified flyback for automotive HID lamps supply

This paper presents an electronic ballast for driving HID lamps with low frequency square waveform from a DC supply suitable for low power low voltage applications as automotive. From the DC source, a flyback arrangement is inserted into a switching structure whose output provides low frequency voltage yet avoiding instability issues. Proposal´s main advantage is the use of one single choke of simple assembly and only two active switches for current control and inversion. Converter design for CCM is presented in this work, besides an equivalent circuit from a control point of view. Small signal AC model is obtained and a feedback control loop is designed, based upon frequency response stability and performance analysis. Impedance criterion is used to guarantee system´s stability. A prototype is presented and described in detail. For design conformity, experimental and simulation results from Matlab and PSIM are presented, as well as discussions about the converter feasibility.