外文翻譯光伏系統(tǒng)中蓄電池的充電保護IC電路設計

1、 光伏系統(tǒng)中蓄電池的充電保護ic電路設計1.引言太陽能作為一種取之不盡、用之不竭的能源越來越受到重視。太陽能發(fā)電已經(jīng)在很多國家和地區(qū)開始普及，太陽能照明也已經(jīng)在我國很多城市開始投入使用。作為太陽能照明的一個關鍵部分，蓄電池的充電以及保護顯得尤為重要。由于密封免維護鉛酸蓄電池具有密封好、無泄漏、無污染、免維護、價格低廉、供電可靠，在電池的整個壽命期間電壓穩(wěn)定且不需要維護等優(yōu)點，所以在各類需要不間斷供電的電子設備和便攜式儀器儀表中有著廣泛的應用。采用適當?shù)母〕潆妷?，在正常使?防止過放、過充、過流)時，免維護鉛酸蓄電池的浮充壽命可達1216年，如果浮充電壓偏差5%則使用壽命縮短1/2。由此可見，充

2、電方式對這類電池的使用壽命有著重大的影響。由于在光伏發(fā)電中，蓄電池無需經(jīng)常維護，因此采用正確的充電方式并采用合理的保護方式，能有效延長蓄電池的使用壽命。傳統(tǒng)的充電和保護ic是分立的，占用而積大并且外圍電路復雜。目前，市場上還沒有真正的將充電與保護功能集成于單一芯片。針對這個問題，設計一種集蓄電池充電和保護功能于一身的ic是十分必要的。2.系統(tǒng)設計與考慮 系統(tǒng)主要包括兩大部分:蓄電池充電模塊和保護模塊。這對于將蓄電池作為備用電源使用的場合具有重要意義，它既可以保證外部電源給蓄電池供電，又可以在蓄電池過充、過流以及外部電源斷開蓄電池處于過放狀態(tài)時提供保護，將充電和保護功能集于一身使得電路簡化，并且

3、減少寶貴的而積資源浪費。圖1是此ic在光伏發(fā)電系統(tǒng)中的具體應用，也是此設計的來源。 免維護鉛酸蓄電池的壽命通常為循環(huán)壽命和浮充壽命，影響蓄電池壽命的因素有充電速率、放電速率和浮充電壓。某些廠家稱如果有過充保護電路，充電率可以達到甚至超過2c(c為蓄電池的額定容量)，但是電池廠商推薦的充電率是c/20c/3。電池的電壓與溫度有關，溫度每升高1，單格電池電壓下降4 mv，也就是說電池的浮充電壓有負的溫度系數(shù)-4 mv/。普通充電器在25處為最佳工作狀態(tài)；在環(huán)境溫度為0時充電不足；在45時可能因嚴重過充電縮短電池的使用壽命。要使得蓄電池延長工作壽命，對蓄電池的工作狀態(tài)要有一定的了解和分析，從而實現(xiàn)對

4、蓄電池進行保護的目的。蓄電池有四種工作狀態(tài):通常狀態(tài)、過電流狀態(tài)、過充電狀態(tài)、過放電狀態(tài)。但是由于不同的過放電電流對蓄電池的容量和壽命所產(chǎn)生的影響不盡相同，所以對蓄電池的過放電電流檢測也要分別對待。當電池處于過充電狀態(tài)的時間較長，則會嚴重降低電池的容量，縮短電池的壽命。當電池處于過放電狀態(tài)的時間超過規(guī)定時間，則電池由于電池電壓過低可能無法再充電使用，從而使得電池壽命降低。 根據(jù)以上所述，充電方式對免維護鉛酸蓄電池的壽命有很大影響，同時為了使電池始終處于良好的工作狀態(tài)，蓄電池保護電路必須能夠?qū)﹄姵氐姆钦９ぷ鳡顟B(tài)進行檢測，并作出動作以使電池能夠從不正常的工作狀態(tài)回到通常工作狀態(tài)，從而實現(xiàn)對電池的

5、保護。3.單元模塊設計3.1充電模塊 芯片的充電模塊框圖如圖2所示。該電路包括限流比較器、電流取樣比較器、基準電壓源、欠壓檢測電路、電壓取樣電路和邏輯控制電路。 該模塊內(nèi)含有獨立的限流放大器和電壓控制電路，它可以控制芯片外驅(qū)動器，驅(qū)動器提供的輸出電流為2030 ma，可直接驅(qū)動外部串聯(lián)的調(diào)整管，從而調(diào)整充電器的輸出電壓與電流。電壓和電流檢測比較器檢測蓄電池的充電狀態(tài)，并控制狀態(tài)邏輯電路的輸入信號。當電池電壓或電流過低時，充電啟動比較器控制充電。電器進入涓流充電狀態(tài)，當驅(qū)動器截止時，該比較器還能輸出20 ma左右，進入涓流充電電流。這樣，當電池短路或反接時，充電器只能以小電流充電，避免了因充電電

6、流過大而損壞電池。此模塊構(gòu)成的充電電路充電過程分為二個充電狀態(tài):大電流恒流充電狀態(tài)、高電壓過充電狀態(tài)和低電壓恒壓浮充狀態(tài)。充電過程從大電流恒流充電狀態(tài)開始，在這種狀態(tài)下充電器輸出恒定的充電電流。同時充電器連續(xù)監(jiān)控電池組的兩端電壓，當電池電壓達到轉(zhuǎn)換電壓過充轉(zhuǎn)換電壓vsam時，電池的電量己恢復到放出容量的70%90%，充電器轉(zhuǎn)入過充電狀態(tài)。在此狀態(tài)下，充電器輸出電壓升高到過充電壓voc，由于充電器輸出電壓保持恒定不變，所以充電電流連續(xù)下降。當電流下降到過充中止電流ioct時，電池的容量己達到額定容量的100%，充電器輸出電壓下降到較低的浮充電壓vf。3.2保護模塊 芯片內(nèi)部保護電路模塊框圖如圖3

7、所示。該電路包括控制邏輯電路、取樣電路、過充電檢測電路、過放電檢測比較器、過電流檢測比較器、負載短路檢測電路、電平轉(zhuǎn)換電路和基準電路(bgr)。 此模塊構(gòu)成的保護電路如圖4所示。當芯片的供電電壓在正常工作范圍內(nèi)，且vm管腳處的電壓在過電流i檢測電壓之下，則此時電池處于通常工作狀態(tài)，芯片的充放電控制端co和do均為高電平，這時芯片處于通常工作模式。而當電池放電電流變大，會引起vm管腳處的電壓上升，若vm管腳處的電壓在過電流檢測電壓viov之上，則此時電池處于過電流狀態(tài)，如果這種狀態(tài)保持相應的過電流延時時間tiov，芯片禁止電池放電，這時充電控制端co為高電平，而放電控制端do為低電平，芯片處于過

8、電流模式，一般為了對電池起到更加安全合理的保護，芯片會對電池的不同過放電電流采取不同的過放電電流延時時間保護。一般規(guī)律是過放電電流越大，則過放電電流延時時間越短。當芯片的供電電壓在過充電檢測電壓之上（vddvcu）時，則電池處于過充電狀態(tài)，如果這種狀態(tài)保持相應的過充電延時時間tcu芯片將禁止電池充電，此時放電控制端do為高電平，而充電控制端co為低電平，芯片處于過充電模式。當芯片的供電電壓在過放電檢測電壓之下(vddr2分壓后的輸出電壓，形成了欠壓的正反饋。輸出為高，欠壓鎖定，起到了保護作用。5.仿真模擬結(jié)果與分析 本設計電路采用csmc 0.6 m數(shù)字cmos工藝對電路進行仿真分析。在對電路

9、做整體仿真時，主要觀察的是保護模塊對電池的充放電過程是否通過監(jiān)測vdd電位和vm電位而使芯片的co端和do端發(fā)生相應的變化。圖7所示的整體仿真波形圖是保護模塊隨著電池電壓的變化從通常工作模式轉(zhuǎn)換到過充電模式，然后回到通常工作模式，接著進入過放電模式，最后再回到通常工作模式。由于本設計處于前期階段，各個參數(shù)還需要優(yōu)化，只是提供初步的仿真結(jié)果。6.結(jié)論 設計了一種集蓄電池充電與保護功能于一身的ic。利用此設計既可以減小而積，又可以減少外圍電路元器件。電路同時采用了低功耗設計。由于此項目正在進行設計優(yōu)化階段，完整的仿真還不能達到要求，還需要對各個模塊電路進行優(yōu)化設計。design of a lead

10、-acid battery charging and protecting ic in photovoltaic system1.introductionsolar energy as an inexhaustible, inexhaustible source of energy more and more attention. solar power has become popular in many countries and regions, solar lighting has also been put into use in many cities in china. as a

11、 key part of the solar lighting, battery charging and protection is particularly important. sealed maintenance-free lead-acid battery has a sealed, leak-free, pollution-free, maintenance-free, low-cost, reliable power supply during the entire life of the battery voltage is stable and no maintenance,

12、 the need for uninterrupted for the various types of has wide application in power electronic equipment, and portable instrumentation. appropriate float voltage, in normal use (to prevent over-discharge, overcharge, over-current), maintenance-free lead-acid battery float life of up to 12 16 years fl

13、oat voltage deviation of 5% shorten the life of 1/2. thus, the charge has a major impact on this type of battery life. photovoltaic, battery does not need regular maintenance, the correct charge and reasonable protection, can effectively extend battery life. charging and protection ic is the separat

14、ion of the occupied area and the peripheral circuit complexity. currently, the market has not yet real, charged with the protection function is integrated on a single chip. for this problem, design a set of battery charging and protection functions in one ic is very necessary.2.system design and con

15、siderations the system mainly includes two parts: the battery charger module and the protection module. of great significance for the battery as standby power use of the occasion, it can ensure that the external power supply to the battery-powered, but also in the battery overcharge, over-current an

16、d an external power supply is disconnected the battery is to put the state to provide protection, the charge and protection rolled into one to make the circuit to simplify and reduce valuable product waste of resources. figure 1 is a specific application of this ic in the photovoltaic power generati

17、on system, but also the source of this design. maintenance-free lead-acid battery life is usually the cycle life and float life factors affecting the life of the battery charge rate, discharge rate, and float voltage. some manufacturers said that if the overcharge protection circuit, the charging ra

18、te can be achieved even more than 2c (c is the rated capacity of the battery), battery manufacturers recommend charging rate of c/20 c/3. battery voltage and temperature, the temperature is increased by 1 c, single cell battery voltage drops 4 mv, negative temperature coefficient of -4 mv / c means

19、that the battery float voltage. ordinary charger for the best working condition at 25 c; charge less than the ambient temperature of 0 c; at 45 c may shorten the battery life due to severe overcharge. to make the battery to extend the working life, have a certain understanding and analysis of the wo

20、rking status of the battery, in order to achieve the purpose of protection of the battery. battery, there are four states: normal state, over-current state over the state of charge, over discharge state. however, due to the impact of the different discharge current over-capacity and lifetime of the

21、battery is not the same, so the battery over discharge current detection should be treated separately. when the battery is charging the state a long time, would severely reduce the capacity of the battery and shorten battery life. when the battery is the time of discharge status exceeds the allotted

22、 time, the battery, the battery voltage is too low may not be able to recharge, making the battery life is lower. based on the above, the charge on the life of maintenance-free lead-acid batteries have a significant impact, while the battery is always in good working condition, battery protection ci

23、rcuit must be able to detect the normal working condition of the battery and make the action the battery can never normal working state back to normal operation, in order to achieve the protection of the battery.3.units modular design3.1the charging module chip, charging module block diagram shown i

24、n figure 2. the circuitry includes current limiting, current sensing comparator, reference voltage source, under-voltage detection circuit, voltage sampling circuit and logic control circuit. the module contains a stand-alone limiting amplifier and voltage control circuit, it can control off-chip dr

25、ive, 20 30 ma, provided by the drive output current can directly drive an external series of adjustment tube, so as to adjust the charger output voltage and current . voltage and current detection comparator detects the battery charge status, and control the state of the input signal of the logic ci

26、rcuit. when the battery voltage or current is too low, the charge to start the comparator control the charging. appliances into the trickle charge state when the cut-off of the drive, the comparator can output about 20 ma into the trickle charge current. thus, when the battery short-circuit or rever

27、se, the charger can only charge a small current, to avoid damage to the battery charging current is too large. this module constitutes a charging circuit charging process is divided into two charging status: high-current constant-current charge state, high-voltage charge status and low-voltage const

28、ant voltage floating state. the charging process from the constant current charging status, the constant charging current of the charger output in this state. and the charger continuously monitors the voltage across the battery pack, the battery power has been restored to 70% to 90% of the released

29、capacity when the battery voltage reaches the switching voltage to charge conversion voltage vsam charger moves to the state of charge. in this state, the charger output voltage is increased to overcharge pressure voc is due to the charger output voltage remains constant, so the charging current is

30、a continuous decline. current down to charge and suspend the current ioct, the battery capacity has reached 100% of rated capacity, the charger output voltage drops to a lower float voltage vf.3.2 protection module chip block diagram of the internal protection circuit shown in figure 3. the circuit

31、includes control logic circuit, sampling circuit, overcharge detection circuit, over-discharge detection comparator, overcurrent detection comparator, load short-circuit detection circuit, level-shifting circuit and reference circuit (bgr). this module constitutes a protection circuit shown in figur

32、e 4. under the chip supply voltage within the normal scope of work, and the vm pin voltage at the overcurrent detection voltage, the battery is in normal operation, the charge and discharge control of the chip high power end of the co and do are level, when the chip is in normal working mode. larger

33、 when the battery discharge current will cause voltage rise of the vm pin at the vm pin voltage at above the current detection voltage viov, then the battery is the current status, if this state to maintain the tiov overcurrent delay time, the chip ban on battery discharge, then the charge to contro

34、l the end of co is high, the discharge control side do is low, the chip is in the current mode, general in order to play on the battery safer and more reasonable protection, the chip will battery over-discharge current to take over the discharge current delay time protection. the general rule is tha

35、t the over-discharge current is larger, over the shorter the discharge current delay time. above overcharge detection voltage, the chip supply voltage (vdd vcu), the battery is in overcharge state, this state is to maintain the corresponding overcharge delay time tcu chip will be prohibited from cha

36、rging the battery, then discharge control end do is high, and charging control terminal co is low, the chip is in charging mode. when the supply voltage of the chip under the overdischarge detection voltage (vdd r2, the partial pressure of the output voltage, the formation of the undervoltage positive feedback. output, undervoltage lo