双绕组LED驱动模块设计与研究

发布时间：2018-12-23 10:56

【摘要】：LED作为固态光源,因其具有功耗低、寿命长以及节能环保等优点而成为新一代绿色照明光源。LED取代传统照明已成为当前的趋势。根据LED的电学特性,LED驱动电源应当具备高效、高可靠性以及直流驱动等特性。因此高频开关电源已成为LED驱动技术的研究热点,本文将重点研究双绕组LED驱动芯片模块的设计。首先,本文研究了LED光学特性,确定了LED恒流驱动的设计要求。从电源系统中各个拓扑结构的研究出发延伸至芯片内部模块电路的设计,对各种拓扑结构进行了分析并求得输出电流的方程,建立理论波形,由一般演算推导至最终目标方程。其次,对比分析了主流LED驱动恒流源的优缺点,阻容降压型：结构简单、成本低廉、可靠性低；线性恒流驱动器：成本低、无频闪,有利于驱动与灯具集成化设计；非隔离型开关电源：效率高、应用广泛,常用于DC-DC模块电源的设计。最后,从用电安全方面考虑,隔离型开关电源更适用于家居照明。因此本文将重点研究隔离型LED驱动恒流芯片设计。针对传统隔离型LED驱动电源控制复杂、成本高同时系统元器件数量多,可靠性低等缺点。论文介绍了反激原边控制LED驱动电源,该类型电源省去传统电源的副边控制、反馈光耦,其思想主要是通过原边辅助绕组反馈副边退磁信号。本文重点研究双绕组LED驱动电源,利用集成MOS寄生电容的充放电采集副边退磁信号。该方案能够进一步简化系统结构,大大提高系统的可靠性。基于上述思想,设计双绕组LED驱动电源系统及驱动模块。电源系统的技术指标为单电压输入：180-264V,输出电压：66-99V,输出电流：280mA。论文主要设计研究了LED驱动电源系统的启动电路、隔离变压器、采样电阻等。此外,设计了芯片级模块的PWM比较器、带隙基准设计、前沿消隐功能、欠压保护、开路保护等各个重要单元,介绍了逻辑电路的控制策略,利用芯片检测次级绕组上退磁信号进行区域控制。采用模拟调频调光与数字调频调光组合的调光设计方案,通过ADJ管脚电流的变化来改变系统频率从而实现系统调光功能。最后,芯片通过1um 40V工艺仿真,并搭建了应用系统,验证了LED驱动芯片设计的合理性。经测试,芯片的各项特性参数均能够达到系统指标。
[Abstract]:As a solid-state light source, LED has become a new generation of green lighting source because of its advantages of low power consumption, long life, energy saving and environmental protection. LED has become the current trend to replace traditional lighting. According to the electrical characteristics of LED, LED drive power supply should have high efficiency, high reliability and DC drive characteristics. Therefore, high frequency switching power supply has become the research hotspot of LED drive technology. This paper will focus on the design of dual-winding LED driver chip module. Firstly, the optical properties of LED are studied and the design requirements of LED constant current drive are determined. From the study of each topology in the power supply system, it extends to the design of the internal module circuit of the chip. The various topologies are analyzed, the equation of output current is obtained, and the theoretical waveform is established, which is derived from the general calculus to the final objective equation. Secondly, the advantages and disadvantages of mainstream LED drive constant current source are compared and analyzed, such as simple structure, low cost and low reliability, linear constant current driver: low cost, no stroboscopic, which is beneficial to the integrated design of drive and lamps. Non-isolated switching power supply: high efficiency, widely used, often used in the design of DC-DC module power supply. Finally, from the aspect of power safety, the isolated switch power supply is more suitable for household lighting. Therefore, this paper will focus on the design of isolated LED driver constant-current chip. The traditional isolated LED drive power supply has the disadvantages of complex control, high cost, large number of components and low reliability. This paper introduces the flyback primary control LED drive power supply. This type of power supply eliminates the secondary control of the traditional power supply and feedback optocoupler. The main idea is to feedback the secondary demagnetization signal through the primary side auxiliary winding. In this paper, the dual winding LED drive power supply is studied, and the secondary demagnetization signal is collected by the charge-discharge integrated parasitic capacitance of MOS. This scheme can further simplify the system structure and greatly improve the reliability of the system. Based on the above idea, the dual winding LED drive power supply system and driving module are designed. The technical specifications of the power supply system are single voltage input: 180-264V, output voltage: 66-99V, output current: 280mA. In this paper, the starting circuit of LED drive power system, isolation transformer, sampling resistance and so on are designed and studied. In addition, the PWM comparator, bandgap reference design, front blanking function, undervoltage protection, open circuit protection and other important units of chip level module are designed, and the control strategy of logic circuit is introduced. Using chip to detect demagnetization signal on secondary winding to carry on area control. The dimming design scheme of analog frequency modulation dimming and digital frequency modulation dimming is adopted. The system dimming function is realized by changing the frequency of the system through the change of ADJ pin current. Finally, the chip is simulated by 1um 40V process, and the application system is built, which verifies the rationality of the design of LED driver chip. The test results show that each characteristic parameter of the chip can reach the system target.
【学位授予单位】：安徽工程大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM923.34

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