一种低功耗LED开关电源设计

发布时间：2018-03-20 23:32

本文选题：低损耗　切入点：开关电源　出处：《华南理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：开关电源轻巧及高高效的特点优点，可以用于各个领域。开关电源的功耗由开关功率管损耗、开关变压器损耗、整流管损耗及其它辅助电路损耗组成。由于开关功率管损耗在整个电源的损耗中所占的比重最大，本设计着重于利用软开关电路降低开关管的损耗，从而提升开关电源的整体效率。将这种软开关技术应用到LED(Light Emitting Diode)驱动，提升LED电源的整体效率。利用电容电感的谐振技术，通过变压器的漏感及开关管并联电容，为即将开通的功率开关管提供零电压导通的条件而实现了软开关工作状态。这样避免了开关管的电流电压的交叠，降低了功率开关管的损耗，提高了LED电源的效率。根据仿真的结果，在60kHz的开关频率下，开关功率管的损耗在软开关时只有其硬开关时的一半左右。采用单片机为软开关电源的主控芯片，单片机的AD输入口为电流电压反馈信号的输入口，由两个NMOS管及开关变压器组成半桥转换电路。单片机输出只有5V，并且NMOS管接高压端需要自举驱动。采用专用的芯片实现了电平转换及自举驱动。通过在两个开关管并联电容，并利用变压器的漏感对电容的充放电，实现了两个开关管均处于软开关开关模式工作。为了简化计算过程，利用计算机仿真优化电路设计。对电路的实施了多项测试工作。测试结果表明电源具有恒流特性满足LED驱动要求，电源效率达到91%以上。
[Abstract]:Switching power supply has the advantages of light and high efficiency, and can be used in various fields. The power consumption of switching power supply is caused by switching power tube loss, switching transformer loss, Rectifier loss and other auxiliary circuit losses. Since switching power transistor losses account for the largest proportion of the total power loss, this design focuses on the use of soft switching circuit to reduce the switching loss. In order to improve the overall efficiency of the switching power supply, this soft switching technology is applied to the LED(Light Emitting Diode driver to improve the overall efficiency of the LED power supply. By using the resonant technique of capacitive inductance, the leakage inductance of transformer and the shunt capacitance of switch tube, The soft switching state is realized by providing the condition of zero voltage conduction for the on-off power switch, which avoids the overlap of the current and voltage of the switch and reduces the loss of the power switch. The efficiency of the LED power supply is improved. According to the simulation results, the loss of the switching power transistor is only about half of that of the hard switch when the switching frequency is 60 kHz. The single-chip microcomputer is used as the main control chip of the soft-switching power supply, and the AD input port of the single-chip microcomputer is the input port of the current-voltage feedback signal. The half-bridge conversion circuit is composed of two NMOS transistors and switch transformers. The output of single-chip microcomputer is only 5V, and the high voltage end of NMOS transistor needs bootstrap drive. A special chip is used to realize the level conversion and bootstrap drive. By using the leakage inductance of transformer to charge and discharge the capacitance, the two switches are in soft switching mode. In order to simplify the calculation process, the computer simulation is used to optimize the circuit design. Many tests are carried out on the circuit. The test results show that the constant current characteristic of the power supply meets the requirements of LED drive, and the efficiency of the power supply is over 91%.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN86

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