Purpose

The purpose of this study is to design a more flexible and larger range of the dimming circuit that achieves the independence of multiple LED strings drive and can time-multiplex the power circuit.

Design/methodology/approach

The state-space method is used to model the BUCK circuit working in Pseudo continuous conduction mode, analyze the frequency characteristics of the system transfer function and design the compensation network. Build a simulation platform on the Orcad PSPICE platform and verify the function of the designed circuit through the simulation results. Use Altium Designer 16 to draw the printed circuit board, complete the welding of various components and use the oscilloscope, direct current (DC) power supply and a signal generator to verify the circuit function.

Findings

A prototype of the proposed LED driver is fabricated and tested. The measurement results show that the switching frequency can be increased to 1 MHz, Power inductance is 2.2 µH, which is smaller than current research. The dimming ratio can be set from 10% to 100%. The proposed LED driver can output more than 48 W and achieve a peak conversion efficiency of 91%.

Originality/value

The proposed LED driver adopts pulse width modulation (PWM) dimming at a lower dimming ratio and adopts DC dimming at a larger dimming ratio to realize switching PWM dimming to analog dimming. The control strategy can be more precise and have a wide range of dimming.

中文翻译：

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基于 GaN eHEMT 的大功率 PCCM LED 驱动器，具有混合调光模式

目的

本研究的目的是设计一种更灵活、更大范围的调光电路，实现多个LED串驱动的独立性，并可对电源电路进行时分复用。

设计/方法/方法

采用状态空间法对工作在伪连续导通模式下的BUCK电路进行建模，分析系统传递函数的频率特性，设计补偿网络。在Orcad PSPICE平台上搭建仿真平台，通过仿真结果验证设计电路的功能。使用 Altium Designer 16 绘制印刷电路板，完成各种元件的焊接，并使用示波器、直流（DC）电源和信号发生器来验证电路功能。

发现

制造并测试了所提出的 LED 驱动器的原型。测量结果表明，开关频率可以提高到1 MHz，功率电感为2.2 µH，比目前研究的要小。调光率可设置为 10% 至 100%。所提出的 LED 驱动器可输出超过 48 W 的功率并实现 91% 的峰值转换效率。

原创性/价值

所提出的LED驱动器采用较低调光比的脉宽调制(PWM)调光和较大调光比的直流调光来实现PWM调光到模拟调光的切换。控制策略可以更精确，调光范围更广。