Design consideration of self-oscillating full-bridge electronic ballast for metal halide lamp at 2.65MHz operating frequency

This paper presents the design consideration of the self-oscillating full-bridge electronic ballast for metal halide lamp at 2.65MHz operating frequency. The self-oscillating full-bridge electronic ballast is operated at 2.65MHz to avoid the acoustic-resonance problem of the metal halide lamp and meet the EMI limitation by IEC regulation. The gate-to-source capacitor of the MOSFETs is considered to derive the design equation of the magnetizing inductor for the current transformer in the self-oscillating gate-drive network. Based on the prototype circuit of a 35-W self-oscillating full-bridge electronic ballast with constant-lamp-current control and no-lamp-protection scheme at 2.65MHz operating frequency, the simulation and experimental results are used to validate the effect from gate-to-source capacitor, the proposed design equation, and the design criteria.