Evaluation of Losses in HID Electronic Ballast Using Silicon Carbide MOSFETs

HID lamps are used in applications where high luminous intensity is desired. They are used in a wide range of applications from gymnasiums to movie theatres, from parking lots to indoor aquaria, from vehicle headlights to indoor gardening. They require ballasts during start-up and also during operation to regulate the voltage and current levels. Electronic ballasts have advantages of less weight, smooth operation, and less noisy over electromagnetic ballasts. A number of topologies are available for the electronic ballast where control of power electronic devices is exploited to achieve the performance of a ballast for lighting. A typical electronic ballast consists of a rectifier, power factor control unit, and the resonant converter unit. Power factor correction (PFC) was achieved using a boost converter topology and average current mode control for gate control of the boost MOSFET operating at a frequency of 70 kHz. The PFC was tested with Si and SiC MOSFET at 250 W resistive load for varying input from 90 V to 264 V. An efficiency as high as 97.4% was achieved by Si MOSFET based PFC unit. However, for SiC MOSFET, the efficiency decreased and was lower than expected. A maximum efficiency of 97.2% was achieved with the SiC based PFC. A simulation model was developed for both Si and SiC MOSFET based ballasts. The efficiency plots are presented. A faster gate drive for SiC MOSFET could improve the efficiency of the SiC based systems.