An Improved Hybrid LED Driver

The continuous improvement of solid-state lighting technologies demands efficient and reliable LED drivers capable of minimizing switching losses while maintaining high power quality. Even a slight improvement in efficiency can have a significant economic impact, given the widespread adoption of LED lighting. This paper presents an experimental investigation of an improved hybrid LED driver that combines dynamic LED string reconfiguration with a low-power auxiliary switching stage to enhance efficiency. The proposed architecture employs protective diodes connected in series with MOSFETs, which effectively reduce switching stress without introducing significant conduction losses. A 200 W laboratory prototype with five LED strings was developed and tested under input voltages of 160-270 Vac at 50 Hz. Simulation and experimental results demonstrate good agreement, confirming the theoretical predictions. The prototype achieved a peak efficiency of 98.6% at 230 VAC, with a power factor of 0.98 and a total harmonic distortion of 11%. The experimental study confirms the practical feasibility and relative simplicity of the proposed improved hybrid driver. The switching transients and voltage stresses on transistors and diodes were significantly reduced. Low switching losses and the limited conduction losses of the protection diodes make it feasible to achieve future monolithic integration, combining not only the power transistors and control circuitry but also the protection diodes within a single chip.