Analysis and design of discrete sliding mode control for a non resonant electronic ballast

René Osorio^*, Mario Ponce, Marco Antonio Oliver, Victor Hugo Olivares, and Mario Juárez

Analysis and design of a dimming control based on the Discrete Sliding Mode Control (DSMC) strategy for electronic ballast (without resonant tank) is presented. To avoid the acoustic resonance phenomenon, the proposed scheme feeds the lamp with low frequency square waves, and then, to stabilize the lamp current, a dc-dc converter with a closed-loop control stage is included. For this purpose, a buck converter with DSMC control is used. A fast response and good reference pursuit is obtained, avoiding the lamp turning off or the lamp destruction when the dimming control is implemented. A reduction in electronic elements is achieved and the reliability of the overall system is incremented with the DSMC compared to the analog Sliding Mode Control strategy. The analysis includes the conditions related to the existence of a sliding surface and the stability conditions. The simulations are made with a nonlinear dynamic lamp model. Analysis, simulation and experimental results of the proposed electronic ballast, and the control stage are presented.

Keywords: Electronic ballast, acoustic resonances, Discrete Sliding Mode Control, square waveforms, buck converter, continuous conduction mode, dimming.