Journal of South China University of Technology (Natural Science Edition) ›› 2018, Vol. 46 ›› Issue (10): 32-41.doi: 10.3969/j.issn.1000-565X.2018.10.005

• Power & Electrical Engineering • Previous Articles     Next Articles

A Constant Frequency, Non-isolated, Multi-channel LED Driver Based on Variable Inductor

LIU Junfeng1 TIAN Hanlei2 SUN WeiHua3 ZENG Jun3   

  1.   1． School of Automation Science and Engineering，South China University of Technology，Guangzhou 510640，Guangdong，China;
    2． School of Electrical Engineering，Hebei University of Science and Technology，Shijiazhuang 050080，Hebei，China;
    3． School of Electric Power，South China University of Technology，Guangzhou 510640，Guangdong，China
  • Received:2018-01-22 Revised:2018-05-09 Online:2018-10-25 Published:2018-09-01
  • Contact: 曾君( 1979-) ，女，博士，教授，主要从事新能源发电技术研究 E-mail:junzeng@scut.edu.cn
  • About author:刘俊峰( 1978-) ，男，博士，副教授，主要从事电力电子技术研究
  • Supported by:
    National Natural Science Foundation of China

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Abstract: The capactive charge balance scheme is widely adopted to eliminate current imbalance in driving multi-channel LEDs due to the high accuracy of current sharing. In order to get the required LED driving current, variable frequency control directly leads to large reactive circulation and increases the stress of devices, and the EMI circuit is complex. Soft switching can’t be guaranteed by constant frequency operation under load variations. Hence, a multiplex LED dimming circuit based on variable inductance (VI) is proposed in this paper, which completes the constant frequency operation, alleviates the complexity of EMI circuit, and realizes the ZVS to improve the energy conversion efficiency. The proposed circuit with superimposed half-bridge structure will increase the number of outputs and simultaneously share resonant inductor, so that the power density is improved and the LED dimming unit is simplified. This paper describes the working principle of the circuit, and takes 8-channel LEDs to build 18W experimental prototype for verifying the feasibility of the LED driver.

Key words:  constant frequency, variable inductor, soft switching, current sharing, LED dimming

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