李偉 - 文獻(xiàn)翻譯

1、 黃河科技學(xué)院畢業(yè)設(shè)計(jì)（文獻(xiàn)翻譯） 第 16 頁太陽能陣列模擬器的設(shè)計(jì)和實(shí)現(xiàn)1.1太陽能陣列模擬器普及前景對(duì)于電力系統(tǒng)的衛(wèi)星，地球上的太陽能電池陣列，有太陽能陣列模擬器是必要的，以便測試太陽能的性能和可靠性?；谔柲茈姵氐臄?shù)學(xué)模型，本文設(shè)計(jì)了以實(shí)際的太陽能電池陣列模擬器，通過其可以生成太陽能電池的電流-電壓特性。由于太陽能電池陣列模擬器的實(shí)現(xiàn)是以相同結(jié)構(gòu)和權(quán)力作為真正的系統(tǒng)，所以它可以模擬出實(shí)際操作中大部分程度上真正的太陽能電池陣列。1.2太陽能陣列模擬器背景及目的太陽能是一種可再生能源，在住宅，光伏系統(tǒng)，交通，及航空航天工業(yè)中廣泛使用。目前的空間力量領(lǐng)域，大多數(shù)衛(wèi)星電源系統(tǒng)使用太陽能電池作

2、為它們的權(quán)力核心。衛(wèi)星電源系統(tǒng)的性能直接影響衛(wèi)星的性能和工作壽命。所以，為提高衛(wèi)星電源的性能和可靠性，進(jìn)行系統(tǒng)實(shí)時(shí)仿真和測試具有重要意義。太陽能電池陣列在太空工作中條件是非常重要的，因?yàn)殛柟夂蜏囟茸兓杆?。依?jù)電流-電壓特性，可以測出每一個(gè)太陽能電池隨光照和溫度的參數(shù)。因此有必要模擬太陽能電池陣列的工作，在空間利用太陽能電池陣列模擬器(太陽能電池陣列模擬器，SAS)。進(jìn)行此情景應(yīng)用程序的主要任務(wù)是為各種供電子系統(tǒng)的衛(wèi)星提供保障，同時(shí)允許測試衛(wèi)星對(duì)地面的實(shí)際的太陽能電池陣列。2.1太陽能電池的數(shù)學(xué)模型等效電路通常用于光伏太陽能電池圖1所示。這個(gè)電路由電流源、二極管串聯(lián)電阻和并聯(lián)電阻組成。圖1太陽

3、能電池的等效電路根據(jù)一般二極管模型，二極管電流被描述為：I0是二極管飽和電流，VJ結(jié)電壓，e是電子的電荷，n是二極管質(zhì)量因素依賴于重組過程的結(jié)，通常在1和2之間的間隔，k是玻耳茲曼常數(shù)和T是溫度。然后是太陽能電池的電流-電壓特性：IPH光生成電流，我是輸出電流，V是輸出電壓、串聯(lián)電阻RS，RSh平行阻力。2.2太陽能陣列模擬器硬件設(shè)計(jì)常見問題根據(jù)數(shù)學(xué)模型和等效電路，太陽能電池的輸出電流-電壓曲線是一個(gè)指數(shù)曲線。它可以與電流源減去模擬二極管的電流-電壓曲線。因此，太陽能電池可以模擬電路如圖2所示： 圖2一個(gè)太陽能字符串模塊的示意圖在這個(gè)電路中有兩種反饋循環(huán)：電流反饋環(huán)和電壓反饋循環(huán)。在目前的反饋

4、回路，IREF短路電流的參考，相當(dāng)于照明，可以調(diào)整強(qiáng)度從0到100%。電壓反饋回路，不潔凈的開路電壓引用對(duì)應(yīng)的環(huán)境溫度太陽能電池。當(dāng)反饋電壓小于不潔凈的，放大器A1的輸出是消極和二極管D1關(guān)閉。A2的輸出只是確定IREF和輸出電流是一個(gè)持續(xù)的短路電流。當(dāng)反饋電壓增加，A1的輸出成為積極和二極管D1。A2的輸出是由D1的電流，它增加了輸出電壓增加。因此，輸出電壓增加輸出電流減少是根據(jù)二極管的電流-電壓的特點(diǎn)。電壓反饋回路中，不潔凈的開路電壓引用對(duì)應(yīng)的環(huán)境溫度太陽能電池。當(dāng)反饋電壓小于不潔凈的時(shí)候，放大器A1的輸出是消極和二極管D1關(guān)閉。A2的輸出只是確定IREF和輸出電流是一個(gè)持續(xù)的短路電流。當(dāng)

5、反饋電壓增加，A1的輸出成為積極和二極管D1。A2的輸出是由D1的電流，它增加了輸出電壓增加。因此，輸出電壓增加輸出電流減少根據(jù)二極管的電流-電壓的特點(diǎn)。圖3太陽能電池陣列模擬器的框圖每個(gè)字符串模塊包括兩個(gè)部分：上部和字符串較低的字符串，它們具有相同的電流-電壓特性和串聯(lián)連接。中心的龍頭都是連接到一個(gè)分流器監(jiān)管機(jī)構(gòu)已與SAS相同數(shù)量的分支。的并聯(lián)調(diào)節(jié)器是用來調(diào)節(jié)直流總線電壓并使它穩(wěn)定在一個(gè)預(yù)期的水平。并聯(lián)調(diào)整器檢測到總線電壓與參考電壓相比較； 區(qū)別是放大，給所有的分支機(jī)構(gòu)。每一個(gè)部門包括PI調(diào)節(jié)器和一個(gè)晶體管，分流術(shù)多余的太陽能字符串的當(dāng)前模塊。如下示意圖4中給出了并聯(lián)調(diào)節(jié)器分支。圖4并聯(lián)調(diào)節(jié)

6、器分支示意圖在這條賽道中，Verror實(shí)際直流總線之間的區(qū)別電壓和基準(zhǔn)電壓。參考電壓Vref每個(gè)分支逐漸增加了調(diào)節(jié)變量電阻VR1。放大器A1和A2由PI調(diào)節(jié)器，和晶體管Q1的收藏家是連接到中心抽頭。當(dāng)Verror小于Vref，PI調(diào)節(jié)器驅(qū)動(dòng)Q1 這個(gè)監(jiān)管機(jī)構(gòu)分支機(jī)構(gòu)不工作；當(dāng)Verror更大然后它開始分路電流。3太陽能陣列模擬器控制系統(tǒng)SAS由30字符串模塊，但一個(gè)工業(yè)標(biāo)準(zhǔn)底盤只能持有4字符串模塊。所以4個(gè)模塊及其相關(guān)控制電路安裝在一個(gè)標(biāo)準(zhǔn)底盤和SAS包含8這樣的單位。在SAS單元控制電路中，信號(hào)隔離電路和數(shù)據(jù)采集電路?；诟咚賳卧刂齐娐稟RM7處理器主要用于傳輸和轉(zhuǎn)換數(shù)據(jù)。使用的AT91S

7、AM7S是Atmel的低的成員基于32位RISC引線數(shù)Flash微控制器處理器。它有一個(gè)64 k字節(jié)高速閃光燈和一個(gè)16 k字節(jié)SRAM，大量的外圍設(shè)備，包括兩個(gè)普遍的同步異步接收機(jī)收發(fā)器， 串行外圍接口(SPI)等等。使其方便與PC機(jī)的串行端口和SPI它很容易駕駛系列廣告和DA芯片。隨著高速ARM7，單元控制電路接收從串行端口和解碼數(shù)字控制命令很快，然后將它們轉(zhuǎn)換成模擬信號(hào)。這些信號(hào)由信號(hào)隔離電路隔離，然后每一個(gè)字符串模塊。字符串輸出等模塊狀態(tài)電壓、電流和溫度也轉(zhuǎn)移到單位控制電路由數(shù)據(jù)采集電路。結(jié)構(gòu)SAS的單位，情景應(yīng)用程序，分別由圖5，圖6所示；圖5情景應(yīng)用程序的結(jié)構(gòu)單元圖6情景應(yīng)用程序框

8、圖4仿真和實(shí)驗(yàn)結(jié)果4.1模擬設(shè)計(jì)為了驗(yàn)證前面設(shè)計(jì)的太陽能字符串模塊，需要模擬出來，為此PSPICE模型建立了模擬電流-電壓曲線。其仿真結(jié)果顯示在圖7和圖8上，如下圖7所示，短路電流隨的強(qiáng)度照明Isc。當(dāng)保持Voc和Isc不變?cè)黾?，電?電壓曲線垂直變化。在圖8中，開放電路電壓隨溫度Voc。當(dāng)保持Isc不變和Voc增加，電流-電壓曲線變化水平。這些曲線對(duì)應(yīng)的電流-電壓特性(2)。圖7與不同的照明模擬電流-電壓曲線圖8模擬電流-電壓曲線具有不同的溫度4.2 實(shí)驗(yàn)測試根據(jù)設(shè)計(jì)和模擬，建立2 kw SAS。來檢查每個(gè)太陽能字符串的性能和電流-電壓特性，許多實(shí)驗(yàn)數(shù)據(jù)被繪制不同的電流-電壓曲線。結(jié)果是圖9

9、和圖10所示。在實(shí)驗(yàn)中，太陽能具有相同的Voc和Isc字符串模擬和仿真的電流-電壓曲線非常接近結(jié)果。圖9與不同的照明實(shí)驗(yàn)電流-電壓曲線圖10實(shí)驗(yàn)電流-電壓曲線具有不同的溫度4.3 實(shí)驗(yàn)比較為了驗(yàn)證情景應(yīng)用程序的輸出的一致性特點(diǎn)與實(shí)際的太陽能電池陣列，有必要測試，情景應(yīng)用程序的單個(gè)字符串的電流-電壓曲線和比較，太陽能電池的實(shí)際數(shù)據(jù)。顯示實(shí)驗(yàn)結(jié)果如圖11所示。圖11電流-電壓曲線在這個(gè)實(shí)驗(yàn)中，短路電流設(shè)置為1.16 ，開路電壓是70 v。理論曲線計(jì)算與一個(gè)真正的太陽能電池的參數(shù)，使用太陽能電池的數(shù)學(xué)模型?？梢钥闯鯯AS的電流-電壓曲線實(shí)際的太陽能陣列的完美匹配。它證明了SAS 執(zhí)行在模擬實(shí)際的太陽

10、能電池陣列。5結(jié)論本文依據(jù)一個(gè)實(shí)際的太陽能電池陣列模擬器為基礎(chǔ)，提出了太陽能電池的數(shù)學(xué)模型。通過實(shí)驗(yàn)證明電流-電壓特性的，并把情景應(yīng)用程序非常類似于實(shí)際的太陽能數(shù)組中，所以它可以用來模擬復(fù)雜的操作條件下，真正的太空中太陽能電池陣列。由于模擬器具有實(shí)際太陽能電池陣列相同的輸出力量和陣列結(jié)構(gòu)，因此它可以用來模擬真實(shí)的衛(wèi)星的電力系統(tǒng)。在未來，太陽能陣列模擬器可以作為實(shí)驗(yàn)平臺(tái)，與其他子系統(tǒng)的衛(wèi)星，從而支持其他子系統(tǒng)的地面測試。來源于： Design and Implementation of A Solar Array SimulatorAbstract-In order to test the pe

11、rformance and reliability of solar power system of satellites, solar array simulator on earth is needed. Based on the solar cells mathematic model, this paper designs a practical solar array simulator which can generate the solar cells I-V character. Since the implemented solar array simulator has t

12、he same structure and power as the real system, it can simulate the actual operating of a real solar array to most extent. Experimental results demonstrate the validity of this design which enables the further research on and diagnosis of solar power system.I. INTRODUCTIONSolar energy is a kind of r

13、enewable energy widely used in residential photovoltaic system, transportation, as well as in aerospace industry. In the present space power domain, most of the satellite power systems use solar cells as their power core. The performance of the satellite power system directly affects the satellites

14、performance and working life. So, in order to improve the performance and reliability of the satellite power system, real time simulation and testing is of great significance. Solar array in space works in very critical conditions, sunlight and temperature change rapidly. The I-V characteristic of e

15、very solar cell varies with illumination and temperature. Therefore it is necessary to simulate the solar arrays working conditions in space by using a solar array simulator (Solar Array Simulator, SAS). SASs main task is to supply power for various subsystems on the satellite while permitting the t

16、esting of the actual solar array of satellite on ground.II. THE MATHEMATICAL MODEL OF SOLAR CELLSThe equivalent circuit generally used for the photovoltaic solar cell is shown in Fig. 1. This circuit consists of a current source, a diode, a series resistance and a parallel resistance.Fig. 1. The equ

17、ivalent circuit of the solar cellAccording to general diode model, the diode current can be described asWhere I0 is the diode saturation current, VJ is the junction voltage, e is the charge of electron, n is diode quality factor dependent on the recombination processes in the junction, usually from

18、the interval between 1 and 2, k is Boltzmanns constant and T is temperature.Then the I-V character of solar cells isWhere IPH is light generated current, I is output current, V is output voltage, RS is series resistance, RSh is parallel resistance.III. HARDWARE DESIGNAccording to the mathematical mo

19、del and equivalent circuit, the output I-V curve of the solar cell is an exponent curve. It can be simulated with a current source minus a diodes I-V curve. Therefore, the solar cell can be simulated with the circuit shown in Fig. 2.Fig. 2. The schematic of a solar string moduleIn this circuit there

20、 are two feedback loops: a current feedback loop and a voltage feedback loop. In the current feedback loop, IREF is the short circuit current reference, corresponds to the intensity of the illumination and can be adjusted from 0 to 100%. In the voltage feedback loop, TREF is the open circuit voltage

21、 reference which corresponds to the ambient temperature of the solar cell. When the feedback voltage is less than TREF, the amplifier A1s output is negative and diode D1 turns off. Then A2s output is only determining by the IREF and output current is a constant short circuit current. When the feedba

22、ck voltage increases, A1s output becomes positive and diode D1 turns on. A2s output is determined by D1s current, it increases with the output voltage increases. So the output voltage increases with the output current decreases according to the diodes I-V characteristic.In order to simulate the real

23、 satellite power system, a solar array simulator is built up with 30 identical string modules. The block diagram is shown in Fig. 3.Fig. 3. The block diagram of solar array simulatorEvery string module includes two parts: upper string and lower string, they have the same I-V characteristic and are c

24、onnected in series. All the center taps are connected to a shunt regulator which has the same amount of branches with SAS. The shunt regulator is used to regulate DC bus voltage and make it stable in an expected level. The shunt regulator detects the bus voltage and compares it with the reference vo

25、ltage; the difference is amplified and given to all the branches. Each branch includes a PI regulator and a transistor, which shunts redundant current of a solar string module. The schematic of a shunt regulator branch is given in Fig. 4.Fig. 4. a shunt regulator branch schematicIn this circuit, Ver

26、ror is the difference between actual DC bus voltage and reference voltage. The reference voltage Vref of each branch is gradually increased by adjusting the variable resistance VR1. Amplifier A1 and A2 consists of a PI regulator, and the collector of transistor Q1 is connected to the center tap. Whe

27、n Verror is smaller than Vref, the PI regulator drives Q1 off and this regulator branch doesnt work; when Verror is bigger then it works and begins to shunt current.IV. CONTROL SYSTEMThe SAS consists of 30 string modules, but an industrial standard chassis can only hold 4 string modules. So 4 module

28、s and their releted control circuits are mounted in a standard chassis and a SAS contains 8 such units. In a SAS unit there are a unit control circuit, a signal isolation circuit and a data acquisition circuit. The unit control circuit based on a high speed ARM7 processor is mainly used to transfer

29、and convert data. The AT91SAM7S used is a member of Atmels low pin-count Flash microcontrollers based on the 32-bit RISC processor. It features a 64k byte high-speed Flash and a 16k byte SRAM, a large set of peripherals, include two universal synchronous asynchronous receiver transceiver (USART), a

30、serial peripheral interface (SPI) and so on. The USART makes it convenient to be connected with PCs serial port and SPI makes it easy to drive serial AD and DA chips.With the high speed ARM7, the unit control circuit receives digital control commands from serial port and decodes it quickly, then con

31、verts them to analog signals by DA. These signals are isolated by the signal isolation circuit and then given to every string module. String module states such as output voltage, current and temperature are also transferred to unit control circuit by data acquisition circuit. Fig. 5 is the structure

32、 of a SAS unit. The SAS is controlled by an industrial PC. In order to control 8 SAS units by serial ports, a master control board is developed to extend serial port. The master control board also based on an ARM has two serial ports, one port is connected with the computer and the other is connecte

33、d with 8 units which forms a master-client structure. It transfers control commands to 8 units and gets unit states by polling mode. The SAS block diagram is hown in Fig. 6.Fig. 5. structure of a SAS unitV. SIMULATION AND EXPERIMENT RESULTSA. SimulationIn order to verify the previously designed sola

34、r string module, a PSPICE model is built up to simulate the I-V curve. The simulation results are shown in Fig. 7 and Fig. 8. As is shown in Fig. 7, the short circuit current varies with the intensity of the illumination Isc. When keeping Voc unchanged and Isc increased, the I-V curve vertically shi

35、fts up. In Fig. 8, the open circuit voltage varies with the temperature Voc. When keeping Isc unchanged and Voc increased, the I-V curve shifts right horizontally. These curves correspond to the I-V characteristic given in (2).Fig. 7. simulated I-V curves with different illuminationFig. 8. simulated

36、 I-V curves with different temperatureB. ExperimentsBased on the design and simulation, a 2kw SAS is built up. To examine every solar strings performance and I-V characteristic, many experimental data has been taken to draw different I-V curves. The results are shown in Fig. 9 and Fig. 10. In the ex

37、periments, the solar string has the same Voc and Isc with the simulation, and the I-V curves are very close to the simulation results.Fig. 9. experimental I-V curves with different illuminationFig. 10. experimental I-V curves with different temperatureC. ComparisonIn order to verify the consistency of the SASs output