發(fā)布時(shí)間：2018-03-05 21:33

  本文選題：LED驅(qū)動(dòng)電源　切入點(diǎn)：原邊反饋　出處：《電子科技大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：LED應(yīng)用于照明,具有壽命長(zhǎng)、節(jié)能環(huán)保、安全可靠等優(yōu)點(diǎn),隨著近年來(lái)人們對(duì)節(jié)能環(huán)保的不斷重視,LED電源逐漸進(jìn)入人們的視野,并得到了快速的發(fā)展。目前的LED產(chǎn)業(yè)已經(jīng)趨于成熟,并且其發(fā)展方向逐漸趨于結(jié)構(gòu)簡(jiǎn)單化、設(shè)計(jì)功能化。如功率因數(shù)校正(PFC)技術(shù)的引進(jìn),使得LED電源減少了對(duì)電網(wǎng)的諧波污染,提高了電能使用效率;調(diào)光技術(shù)的引進(jìn),使得人們根據(jù)不同場(chǎng)合調(diào)節(jié)光線明暗程度成為可能。模擬調(diào)光技術(shù)是一種結(jié)構(gòu)簡(jiǎn)單,成本低下的調(diào)光實(shí)現(xiàn)方案,廣泛應(yīng)用于對(duì)光線色溫要求不高的低成本的場(chǎng)合。傳統(tǒng)的模擬調(diào)光采用光電耦合器來(lái)反饋輸出電壓或電流信號(hào),本文設(shè)計(jì)了一款采用原邊反饋控制的帶模擬調(diào)光的LED驅(qū)動(dòng)芯片,該芯片由外部控制產(chǎn)生一個(gè)占空比可調(diào)的振蕩信號(hào)來(lái)線性改變恒流的基準(zhǔn)電壓,然后通過(guò)誤差放大器與原邊采樣信號(hào)進(jìn)行比較放大,以調(diào)節(jié)對(duì)功率管開(kāi)關(guān)信號(hào)(PWM)的占空比,最終實(shí)現(xiàn)對(duì)LED電源輸出電流的線性調(diào)節(jié)。原邊反饋控制技術(shù)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(jí)PFC反激式拓?fù)浣Y(jié)構(gòu),利用輸入電流跟隨輸入電壓波形的技術(shù)實(shí)現(xiàn)了芯片功率因數(shù)的校正。芯片內(nèi)部采用了谷底檢測(cè)技術(shù),使得開(kāi)關(guān)管在其壓降為最低的情況下打開(kāi),減小了導(dǎo)通損耗。芯片還包含有過(guò)溫、過(guò)壓、過(guò)流保護(hù)結(jié)構(gòu)的設(shè)計(jì),保證了芯片的正常安全工作。此外,芯片最大關(guān)斷時(shí)間的設(shè)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?fù)浣Y(jié)構(gòu)和內(nèi)部結(jié)構(gòu)框圖,然后分析了芯片恒流功能和PFC功能的實(shí)現(xiàn)。在確定了芯片的整體結(jié)構(gòu)的基礎(chǔ)上,本文針對(duì)調(diào)光環(huán)路的每個(gè)主要環(huán)節(jié),對(duì)包含基準(zhǔn)電壓產(chǎn)生、PWM控制、誤差放大器實(shí)現(xiàn)和線性調(diào)光等電路模塊進(jìn)行了設(shè)計(jì)與分析,并通過(guò)仿真驗(yàn)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(yīng)用Hspice仿真工具,對(duì)芯片整體功能實(shí)現(xiàn)完成了仿真與驗(yàn)證。仿真結(jié)果顯示,當(dāng)輸入交流電壓為220 V時(shí),芯片的恒流輸出為175 mA,當(dāng)調(diào)光占空比為80%、60%、40%和20%時(shí),輸出平均電流分別為141.1mA、107.3 mA、74.6 mA和43.5 mA,可以實(shí)現(xiàn)精度較高的線性調(diào)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(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN312.8

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