本文選題：LED驅動電源　切入點：原邊反饋　出處：《電子科技大學》2015年碩士論文　論文類型：學位論文

【摘要】：LED應用于照明,具有壽命長、節(jié)能環(huán)保、安全可靠等優(yōu)點,隨著近年來人們對節(jié)能環(huán)保的不斷重視,LED電源逐漸進入人們的視野,并得到了快速的發(fā)展。目前的LED產業(yè)已經趨于成熟,并且其發(fā)展方向逐漸趨于結構簡單化、設計功能化。如功率因數(shù)校正(PFC)技術的引進,使得LED電源減少了對電網的諧波污染,提高了電能使用效率;調光技術的引進,使得人們根據(jù)不同場合調節(jié)光線明暗程度成為可能。模擬調光技術是一種結構簡單,成本低下的調光實現(xiàn)方案,廣泛應用于對光線色溫要求不高的低成本的場合。傳統(tǒng)的模擬調光采用光電耦合器來反饋輸出電壓或電流信號,本文設計了一款采用原邊反饋控制的帶模擬調光的LED驅動芯片,該芯片由外部控制產生一個占空比可調的振蕩信號來線性改變恒流的基準電壓,然后通過誤差放大器與原邊采樣信號進行比較放大,以調節(jié)對功率管開關信號(PWM)的占空比,最終實現(xiàn)對LED電源輸出電流的線性調節(jié)。原邊反饋控制技術的采用省去了光耦反饋器件的使用,節(jié)省了芯片面積和成本。它采用單級PFC反激式拓撲結構,利用輸入電流跟隨輸入電壓波形的技術實現(xiàn)了芯片功率因數(shù)的校正。芯片內部采用了谷底檢測技術,使得開關管在其壓降為最低的情況下打開,減小了導通損耗。芯片還包含有過溫、過壓、過流保護結構的設計,保證了芯片的正常安全工作。此外,芯片最大關斷時間的設置,也保證了芯片的正常工作。本文首先分析闡述了芯片的拓撲結構和內部結構框圖,然后分析了芯片恒流功能和PFC功能的實現(xiàn)。在確定了芯片的整體結構的基礎上,本文針對調光環(huán)路的每個主要環(huán)節(jié),對包含基準電壓產生、PWM控制、誤差放大器實現(xiàn)和線性調光等電路模塊進行了設計與分析,并通過仿真驗證了模塊的功能與性能。最后本文采用TSMC_0.5 um BCD工藝,并應用Hspice仿真工具,對芯片整體功能實現(xiàn)完成了仿真與驗證。仿真結果顯示,當輸入交流電壓為220 V時,芯片的恒流輸出為175 mA,當調光占空比為80%、60%、40%和20%時,輸出平均電流分別為141.1mA、107.3 mA、74.6 mA和43.5 mA,可以實現(xiàn)精度較高的線性調光。
[Abstract]:The application of LED in lighting has the advantages of long life, energy saving and environmental protection, safety and reliability, etc. With the increasing attention paid to energy saving and environmental protection in recent years, the power supply of LED has gradually entered people's field of vision. At present, the LED industry has become mature, and its developing direction tends to simplify the structure and design function. For example, the introduction of power factor correction (PFC) technology makes the LED power supply reduce the harmonic pollution to the power grid. The introduction of dimming technology makes it possible for people to adjust the light intensity according to different occasions. Analog dimming technology is a simple structure and low cost dimming scheme. It is widely used in low cost cases where the color temperature of light is not high. The traditional analog dimming uses photocoupler to feedback the output voltage or current signal. In this paper, a LED driver with analog dimming is designed, which adopts the original side feedback control. The chip generates an oscillatory signal with adjustable duty cycle to change the reference voltage of constant current linearly, and then amplifies the signal by comparing the error amplifier with the original sampling signal to adjust the duty cycle of the switch signal PWM. Finally, the linear regulation of output current of LED power supply is realized. The original edge feedback control technology saves the use of optocoupler feedback device, and saves the chip area and cost. It adopts a single-stage PFC flyback topology. Using input current to follow the input voltage waveform, the chip power factor correction is realized. The bottom detection technology is used inside the chip, which makes the switch tube open under the condition that the voltage drop is the lowest. The chip also includes the design of over-temperature, overvoltage and over-current protection structure, which ensures the normal and safe operation of the chip. In addition, the maximum turn-off time of the chip is set. It also ensures the normal operation of the chip. In this paper, the topology structure and internal structure block diagram of the chip are analyzed, then the realization of the constant current function and the PFC function of the chip is analyzed. On the basis of the overall structure of the chip, the whole structure of the chip is determined. In this paper, the circuit modules including reference voltage generation PWM control, error amplifier realization and linear dimming are designed and analyzed for each main link of the dimming loop. The function and performance of the module are verified by simulation. Finally, the whole function of the chip is simulated and verified by using TSMC_0.5 um BCD technology and Hspice simulation tool. The simulation results show that when the input voltage is 220V, The constant current output of the chip is 175 Ma. When the dimming duty cycle is 80% and 20%, the average output current is 141.1 mAn 107.3 Ma 74.6 Ma and 43.5 Ma, respectively, which can achieve high precision linear dimming.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN312.8

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