High Power Long Lifetime LED Drivers

  • Author / Creator
    Mahmoud Rahmani
  • This thesis addresses the design and implementation of durable LED driver for street lighting application. LED based street lighting products are now available in various power ratings, light intensity, and color temperature. Higher efficiency, light quality and Color Rendering Index (CRI), reliability, and reduced maintenance cost are the main reasons that make solid state lighting superior than its counterparts such as High Pressure Sodium, Low Pressure Sodium, Incandescent, and metal halide lighting. Design of LED drivers involves many technical and practical issues. Harsh operating temperature, power density, and power quality have always been practical issues regarding the design of LED drivers. For single phase applications, double frequency power oscillations can create problems for LEDs. Using electrolytic capacitor is known to address power oscillation issues which sacrifices the durability of LED drivers. Power Factor (PF) and Total Harmonic Distortion (THD) are measurements determining the quality of the power transferred in an electrical system. Providing high power factor and lower harmonic distortion is also another challenge when using non-linear loads such as LEDs and gate driver circuits that include rectifiers, and active switching devices. In this thesis a new circuit configuration and control structure is proposed to design a durable, compact LED driver for street lighting application which tackles all the aforementioned challenges. The proposed multi-stage topology employs a boost power converter as the power factor correction and a series resonant converter as the power conversion stage. Exploiting faster dynamic of second stage controller to decouple the input oscillating power from the DC output power made it possible to alleviate the need for a large capacitance on DC link and facilitated the use of film capacitors in which wasn’t primarily the best choice due to film capacitors’ large packages for higher capacitance values. Utilization of film capacitors made the lifespan of the LED driver match the LED lifespan. Generalized peak current control is employed on PFC stage to achieve power factor correction and constant frequency, making it easier to design the output filter, and reducing THD and electromagnetic interference. Second stage of the proposed LED driver consists of a soft-switching high frequency series resonant converter to control the output current which also provides a high power density and electrical isolation. Moreover, comprehensive design of magnetic devices is performed and simulation and experimental results are presented to verify the effectiveness of the design.

  • Subjects / Keywords
  • Graduation date
    Fall 2018
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
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