Comparison of operating parameters of a class e resonant converter based led driver for different quality factors

Advancing technology and a growing population are driving a constantly increasing demand for electrical energy. This necessitates the search for new energy sources and the more efficient use of existing resources. The fact that a significant portion of electrical energy is used for lighting makes it crucial to increase the efficiency of devices used in this field. LEDs are widely preferred due to their higher efficiency and longer lifespan compared to traditional lighting elements. However, their temperature-dependent and nonlinear electrical characteristics necessitate constant current drive. Therefore, suitable driver circuits are required for stable and reliable LED operation. Traditional resistive and linearly regulated LED drive methods, due to their low efficiency, have been replaced by LED driver circuits implemented with DC-DC converters. DC-DC converters offer advantages in terms of cost and volume when operated at high frequencies. However, the hard switching conditions in PWM-controlled converters lead to significant switching losses at high frequencies. Resonant switching converters employing soft switching techniques have been developed to eliminate or mitigate this disadvantage of PWM-switched converters. In this thesis, an LED driver circuit capable of operating under zero-voltage switching conditions at high frequencies using a Class E resonant converter is analyzed and designed. Simulation studies and laboratory experiments were conducted to investigate the changes in the operating parameters of the driver circuit for different quality factors (3, 5, 7, and 9). Simulation studies were conducted in the PSIM program, and a 48 W LED driver prototype operating at a 250 kHz switching frequency was implemented. Simulation and experimental studies revealed that the input current, switch voltage, resonant current, and output power decreased with increasing quality factor. In the simulation studies, the driver's power switch conducts under zero voltage conditions for different quality factors. However, for low quality factors, the switch voltage rises above 0 V without the application of a gate signal. While the experimental studies and simulation studies are consistent in terms of soft switching, the soft switching conditions for quality factor 9, according to the design criteria, cannot be achieved in the experimental studies. The results of the simulation and experimental studies obtained for different quality factors within the scope of this thesis are presented in tables.