Analysis and design of a dimming control using sliding mode control strategy for electronic ballast free of acoustic resonances

In this paper an analysis and design of a dimming control based on sliding mode control (SMC) strategy for electronic ballast (without resonant tank) is presented. The lamp current is stabilized using a DC-DC converter (Buck). The Buck elements can to be shared with the inverter. Likewise a lamp model modification is presented to get more realistic simulation results. To avoid excessive semiconductor losses this ballast operates in continuous conduction mode (CCM), then to stabilize the lamp current a close loop control stage is needed. For this purpose a sliding mode control is used, then a fast response and good reference pursuit is obtained, avoiding the lamp strike out or it be destroyed when dimming control be implemented. To avoid the acoustic resonance phenomenon, the proposed scheme feed the lamp with low frequency square waves. Analysis, simulation and experimental results of the electronic ballast and the control stage are presented.