外文翻譯---基于stm32的恒溫箱溫度控制系統(tǒng)

1、<p>　　Thermo Tank Temperature Control System Based On STM32</p><p>　　Biao QIU(····) , Shi-guang LI(····), Zheng-zhong GAO(····), Xu ZHANG(

2、3;···), Yu RUI(····) </p><p>　　(School of Information and Electrical Engineering, Shandong University of Science and Technology, Qingdao 266510, China)</p><p>

3、　　Abstract-this paper introduced a thermo tank temperature control system based on STM32, Firstly, the temperature acquisition is realized by the high-precision electrical bridge based on constant current source. Then th

4、e augmented PID algorithm realized by software is adopted Butterworth filter is used to convert the output PWM of STM32 to current signal which is used to control the semiconductor control rectifier to adjust the tempera

5、ture. Calibration check and practical application both indicat</p><p>　　Key words-STM32; thermo tank; temperature acquisition; PID</p><p>　　ManuscriptNumber: 1674-8042(2011)01-0064-03</p>

6、<p>　　Dio: 10.3969/j.issn.1674-8042.2011.01.16</p><p>　　1 introduction</p><p>　　Thermo tank can be divided into low temperature thermo tank and high temperature thermo tank according to te

7、mperature range. Heating control thermo tank is one kind of high temperature thermo tank and has a wide range of applications in industrial, medical and scientific areas. As some special thermo tank control system requir

8、e high precision in temperature acquisition and control, the system designed in this paper can measure temperatures from 16℃ to 80℃ and its precision is superior to ±0.05℃.</p><p>　　2 Basic control prin

9、ciples of thermo tank</p><p>　　In this system, temperature acquisition of the inner thermo tank is realized by using platinum resistance as temperature sensor and bridge circuit based on constant current sou

10、rce. Then compare the actual temperature with the temperature set by touch screen. By using augmented PID algorithm to adjust, STM32 outputs 16-bit PWM signals. Then convert PWM signal to voltage signal to control the co

11、nduction angle of Semiconductor Control Rectifier(SCR) which controls the heating tubes. System control </p><p>　　Considering the system accuracy and stability requirements, features of this system include:

12、powerful and high speed ARM STM32F103 as the controller, augmented PID algorithm, and full use of on-chip resources of microcomputer such as ADC, USART and 16-bit PWM output for great control accuracy.</p><p&g

13、t;　　Fig 1 System control principle</p><p>　　3 hardware design</p><p>　　This system includes temperature acquisition bridge circuit, STM32F103, color LCD touch screen control circuit, filtering c

14、ircuit and SCR. In addition, the system has a good man-machine interaction function and can realize real-time monitoring and control by using 5.6 inches color LCD and touch screen. Temperature control system structure is

15、 shown in Fig.2.</p><p>　　Fig 2 System structure</p><p>　　3.1 temperature acquisition and A/D conversion</p><p>　　Among the thermal resistance temperature sensors, platinum resistan

16、ce, with advantage as high precision, stable performance, corrosion resistance and easy to use, is the ideal temperature acquisition component widely used in industrial environments and control systems. As the temperatur

17、e acquisition range is 16℃ to 80℃, Pt1000 is chosen as temperature sensor, which resistance changes with temperature according to certain rules and has good high precision and stable performance.</p><p>　　Un

18、balanced bridge measurement is typical in detect circuits using platinum resistance as temperature sensors[1]. However, the nonlinearity between platinum resistance and temperature and nonlinearity of unbalanced bridge l

19、ead to acquisition error, thus we improved the temperature acquisition bridge circuit. Use constant current source to power the bridge, connect the two bridge arms with precise operational amplifier that is low noise and

20、 low temperature drift, use 4DH2 to constitute constant cu</p><p>　　The ADC of STM32F103 is used to convert analog voltage of temperature into digital signal. The 12-bit ADC is a successive approximation ana

21、log-to-digital converter and has the function of self-calibration. D/D conversion of each channel can be performed in single, continuous, scan or discontinuous mode, and in this system we use continuous mode. The result

22、of ADC is stored in right-aligned 16-bit data register which improves the conversion speed. In addition, the analog watchdog feature allows t</p><p>　　3.2 TM32F103 on-chip resources</p><p>　　TM3

23、2F103 can work in -40℃~105℃ and this meets the requirements of industrial environment. It incorporate the high performance ARM Cortex-M3 32-bits RISC core operating at a 72 MHz frequency, high speed embedded memories (Fl

24、ash memory up to 128Kbytes and SRAM up to 20Kbytes) to store data and program, and an extensive range of enhanced I/Os, most of which have alternate functions and peripherals connected to two APB buses. It has three gene

25、ral purpose 16-bit timers plus two watchdogs, as well as </p><p>　　3.3 Filtering and conversion circuits</p><p>　　In order to realize the convention from PWM signal to analog output, we use the

26、second order low pass filter to filter out the high frequency components and keep DC component and changing duty cycle of PWM signal so that the analog voltage output is got then. Fig.3 shows the designed Butterworth fil

27、ter. After filtering, convert PWM signal to 0~2.5 V to control thyristor conduction angle[3]. Thus we realized the precise control of heating temperature.</p><p>　　Fig 3 Butterworth filter</p><p&

28、gt;　　4 Software design</p><p>　　4.1PID control algorithm</p><p>　　This system uses PID control algorithm which is a basic control method widely used in industrial process control method widely u

29、sed in industrial process control. Augmented PID control algorithm[4] is </p><p>　　uk - uk- 1 = KP ( ek - ek- 1 ) + K 1 ek +</p><p>　　K D ( ek - 2ek- 1 + ek- 2 ) .</p><p>　　However,

30、 if this algorithm was used directly, it could generate a lare overshoot and cause integral saturation easily when starup, stop or adjust substantially. In order to inhibit the emergence of this phenomenon, we use integr

31、al separation as an improvement.</p><p>　　Integral separation won't work until actual temperature is approaching the settings. When it works, it can eliminate static error and improve precision[5]. Block

32、 diagram of integral separation PID is shown in Fig.4.</p><p>　　Fig 4 Integral separate PID algorithm block diagram</p><p>　　4.2 Touch screen software design</p><p>　　It makes human

33、-computer interface much more friendly, more convenient and faster by using touch screen. Use dedicated control chip ADS7843 to connect AMT9532, four-wire resistive touch screen, withSTM32F103, process the touch screen s

34、ignals[6]. Touch screen's software design flow chart is shown in Fig.5.</p><p>　　Fig 5 Touch screen flow chart</p><p>　　Use standard thermometer with 0.001℃ precision as calibration to check

35、 the experimental results. Specific methods: set different temperatures within the appropriate range though touch screen, wait until the temperatures shown in the LCD are stable, then calculate the errors based on the ac

36、tual temperature of standard thermometer with formula:</p><p>　　Error=|set-actual|/set.</p><p>　　The check results are shown in Tab.1.</p><p>　　Tab.1 Calibration results</p>

37、<p>　　6 conclusion</p><p>　　By using 16-bit PWM output, simple filtering circuit conversion circuit, software design and floating-point operations, this system realized 16-bit D/A. Conversion which is v

38、ery hard for common MCU to realize.</p><p>　　The system temperature range is 6℃~80℃ and the resolution of 16-bit control signal could reach to 10‰. The experimental results show that the system definitely ca

39、n reach the control requirement that temperature accuracy is better than ±0.05℃. The application shows that this system has the real-time, flexible, stable high-precision, and low cost advantages, and can meet the i

40、ndustrial requirements of high accuracy, high stability and reliability.</p><p>　　References</p><p>　　[1] Zhaojun Li, Ping Ji, Xiangguang Lou, 2007, Design of high precision temperature control

41、 system. Electronic Measurement Technology. (2): 146-148.</p><p>　　[2] ST Microelectronics Corporation, 2007. STM32F103XX Data sheet.</p><p>　　[3] Dayong Xia, Xiaohui Zhou, Zeng Zhao, Bofeng Che

42、n, Endian Hu,2007. Temperature control system of single-chip of model MCS-51. Industrial Instrumentation & Automation, (1):43-47.</p><p>　　[4] Lin Wu, Enping Lou, Dongqing Hou, Liang Xu, 2006, Wireless t

43、emperature and humidity control system based on PID arithmetic. Chinese Journal of Scientific Instrument, 27(21):619-620.</p><p>　　[5] Yan Zhao, Guangzhi Yang, 2006. Automatic measuring system in constant te

44、mperature for oxygen content based on singlechip. Chinese Journal of Scientific Instrument, s1.</p><p>　　[6] Songmei Zhang, Junkai Liang, Longji Liu, 2008. Deign of thermo tank temperature control system bas

45、ed on C8051F. Electronic Measurement Technology, 31(9): 147-149.</p><p>　　基于STM32的恒溫箱溫度控制系統(tǒng)</p><p>　　摘要—這篇文章介紹了一個基于STM32的恒溫箱溫度控制系統(tǒng)，首先，由基于常流源的高精度電橋獲取溫度，然后，由軟件實(shí)現(xiàn)的擴(kuò)充型PID算法在這里得到應(yīng)用，使用巴特沃茲濾波器（最平坦濾波器）將

46、STM32輸出的PWM轉(zhuǎn)換成電流信號來控制半導(dǎo)體整流器從而調(diào)節(jié)溫度，校準(zhǔn)檢測和實(shí)際應(yīng)用都表明這個系統(tǒng)可靠、精度高、可行性好，并且能夠滿足現(xiàn)實(shí)需要。</p><p>　　關(guān)鍵字—STM32；恒溫箱；溫度獲??；PID。</p><p>　　原稿編號：1674-8042-（2011）01-0064-03</p><p>　　Dio：10.3964/j.issn.1674-

47、8042.2011.01.16</p><p><b>　　1 引言</b></p><p>　　根據(jù)溫度范圍，恒溫箱分為低溫箱和高溫箱兩種，加熱控制恒溫箱是一種高溫恒溫箱，并且它在工業(yè)、醫(yī)療和科學(xué)領(lǐng)域有著廣泛的應(yīng)用，因為一些特殊恒溫箱控制系統(tǒng)在溫度測量及控制方面都要求很高的精度，所以這篇文章中所設(shè)計的系統(tǒng)能夠測量16℃~18℃的溫度，并且它的精度高于±0.

48、05℃。ARM因其強(qiáng)大的功能和低成本的優(yōu)點(diǎn)正逐漸占領(lǐng)微電子市場，也正因如此，設(shè)計一個基于ARM的高精、簡單結(jié)構(gòu)和低成本的溫度控制系統(tǒng)便具有重要的實(shí)際意義和價值。</p><p>　　2恒溫箱控制的基本原理</p><p>　　在這個系統(tǒng)中，為獲取恒溫箱內(nèi)部的溫度，使用鉑絲電阻作為溫度傳感器和基于常流源的橋式電路。然后，將實(shí)際溫度與通過觸摸屏設(shè)定的溫度作比較。通過使用擴(kuò)充型PID算法來調(diào)節(jié)S

49、TM32輸出的16比特脈沖寬度調(diào)制信號，然后將PWM信號轉(zhuǎn)換成電壓信號來控制半導(dǎo)體控制整流器（SCR）的導(dǎo)通角，從而控制加熱管，系統(tǒng)控制原理示于圖1</p><p><b>　　圖1 系統(tǒng)控制原理</b></p><p><b>　　3硬件設(shè)計</b></p><p>　　這個系統(tǒng)包括溫度獲取橋式電路、STM32F103、

50、彩色LCD觸摸屏控制電路、濾波電路和SCRC（半導(dǎo)體控制整流器），另外，這個系統(tǒng)使用5.6英寸彩色LCD和觸摸屏，有著優(yōu)良的人機(jī)交互功能，并且能夠?qū)崿F(xiàn)實(shí)時監(jiān)測和控制。溫度控制系統(tǒng)結(jié)構(gòu)示于圖2</p><p><b>　　圖2 系統(tǒng)結(jié)構(gòu)</b></p><p>　　3.1溫度獲取和模擬/數(shù)字轉(zhuǎn)換</p><p>　　在所有的熱敏電阻溫度傳感器中，

51、鉑絲電阻因其高精度、穩(wěn)定性好、耐腐蝕以及易于使用的優(yōu)點(diǎn)而成為理想的溫度獲取原件并在工業(yè)環(huán)境和控制系統(tǒng)中得到了廣泛的應(yīng)用?；跍y溫范圍為16℃~18℃，Pt1000的組織依確定關(guān)系隨溫度的變化而變化，并且精度高、穩(wěn)定性好，所以選擇它作為溫度傳感器。</p><p>　　在以鉑絲電阻作為溫度傳感器的測量電路中，非平衡橋測量時一種典型應(yīng)用。然而，鉑絲電阻的阻值與溫度之間的非線性關(guān)系以及非平衡橋的非線性性會導(dǎo)致獲取值出錯

52、，因此，我們改進(jìn)了溫度測量橋式電路。使用常電流源給電橋供電，使用具有低噪聲和低溫漂的高精度可操作放大器連接兩個網(wǎng)橋，使用4DH2組建恒流源以輸出0.5A電流，因此，流經(jīng)鉑絲電阻的電流等效于恒流源。</p><p>　　STM32F103中的ADC用來將溫度的模擬電壓值轉(zhuǎn)換成數(shù)字信號，這個12比特ADC是一個連續(xù)近似模擬到數(shù)字的轉(zhuǎn)換器，并且具有自我校準(zhǔn)功能。每個通道的A/D轉(zhuǎn)換均可工作在獨(dú)立、連續(xù)掃描或不連續(xù)模式下

53、，而在這個系統(tǒng)中，我們使用連續(xù)模式，ADC的轉(zhuǎn)換值存儲在右排16比特數(shù)據(jù)寄存器中，從而提高了轉(zhuǎn)換速度，另外，模擬監(jiān)測機(jī)構(gòu)能夠在輸入電壓超過用戶定義的高門限或低門限時進(jìn)行監(jiān)測。</p><p>　　3.2TM32F103片上資源</p><p>　　TM32F103能夠工作在-40℃~105℃的溫度范圍內(nèi)，這符合工業(yè)環(huán)境的要求，它整合了工作頻率為72MHz的高性能ARM Cortex-M3

54、32比特RSIC核心、用來存儲數(shù)據(jù)和程序的告訴嵌入式存儲器（高達(dá)128K字節(jié)的閃存和高達(dá)20K字節(jié)的SRAM靜態(tài)只讀存儲器）以及更多增強(qiáng)的I/O口，這些接口中的大部分可以工作在不同功能下并且具有連接到2個APB總線的外圍設(shè)備。它包含3個通用16字節(jié)定時器，附加兩個監(jiān)測器。另外還有用來與LCD進(jìn)行通信的標(biāo)準(zhǔn)型和增強(qiáng)型交流交互OSART，更重要的是，它提供2個轉(zhuǎn)換速度為1μS的12比特ADC，這使它適合于高速獲取和處理的情況。這是選擇TM3

55、2F103作為這個系統(tǒng)的核心控制器的一個重要原因。</p><p>　　3.3 濾波和轉(zhuǎn)換電路</p><p>　　為了實(shí)現(xiàn)從PWM信號到模擬輸出的轉(zhuǎn)換，我們使用第二個低通濾波器濾除高頻分量，保留直流分量，并且改變PWM信號的工作周期從而獲得用于輸出的模擬電壓。DS18B20測溫原理框圖示出了所設(shè)計的巴特霍茲濾波器，濾波之后，將PWM信號轉(zhuǎn)換至0—2.5V范圍內(nèi)的電壓信號以控制硅控濾波器的

56、傳輸角，因此我們實(shí)現(xiàn)了對加熱管的精確控制。</p><p>　　圖3 巴特霍茲濾波器</p><p><b>　　4 軟件設(shè)計</b></p><p>　　4.1 PID控制算法</p><p>　　這個系統(tǒng)使用PID控制算法，這個算法是一種已在工作處理控制中廣泛應(yīng)用的基本控制方法，擴(kuò)充形PID控制算法如下：</p

57、><p>　　然而，如果直接使用這個算法，它會導(dǎo)致很大的溢出而且在啟動、停止或是大幅度調(diào)試的時候引起整體飽和，為了抑制這個現(xiàn)象的發(fā)生，我們使用整型分離作為改進(jìn)方式，直到世紀(jì)溫度接近設(shè)定值時，整型分離才會工作，當(dāng)它工作時，可以去除靜態(tài)錯誤，從而提高精度，整型分離PID框圖示于圖4。</p><p>　　圖4 整型分離PID算法框圖</p><p>　　4.2 觸摸屏軟件設(shè)

58、計</p><p>　　使用觸摸屏可使人機(jī)交互更加友好、方便和快捷，使用專用的控制芯片ADS7843連接到四線電阻觸摸屏AMT9532，結(jié)合STM32F103處理觸摸信號，觸摸屏的軟件流程圖示于圖5。</p><p>　　圖5 觸摸屏流程圖</p><p><b>　　5 實(shí)驗結(jié)果</b></p><p>　　使用精度

59、為0.001℃的熱度計作為校準(zhǔn)時實(shí)驗結(jié)果進(jìn)行檢測，特別方法：</p><p>　　通過觸摸屏在溫度范圍內(nèi)設(shè)定合適的溫度，等待LCD上顯示的溫度數(shù)據(jù)穩(wěn)定后，通過由熱度計讀取的數(shù)值與該值作比較，計算其誤差，計算公式如下：</p><p>　　誤差=｜設(shè)定值—實(shí)際值｜/設(shè)定值</p><p><b>　　檢測結(jié)果示于表1</b></p>

60、<p><b>　　表1 校準(zhǔn)結(jié)果</b></p><p>　　———————————————————————————————</p><p>　　設(shè)定值（℃） 顯示值（℃） 實(shí)際值（℃） 誤差（%）</p><p>　　———————————————————————————————</p&

61、gt;<p>　　16.00 15.98 15.977 0.2</p><p>　　30.00 30.00 29.988 0.4</p><p>　　40.00 40.01

62、 40.009 0.2</p><p>　　50.00 50.00 50.014 0.3</p><p>　　60.00 60.01 60.011 0.2</p><p

63、>　　70.00 69.97 70.020 0.3</p><p>　　80.00 79.98 80.037 0.5</p><p>　　———————————————————————————————</p>

64、<p><b>　　6 結(jié)論</b></p><p>　　通過使用16比特PWM輸出，簡單濾波電路、轉(zhuǎn)換電路、軟件設(shè)計及浮點(diǎn)操作，這個系統(tǒng)實(shí)現(xiàn)了普通MCU難以實(shí)現(xiàn)的16比特D/A轉(zhuǎn)換，系統(tǒng)溫度控制范圍為16℃~80℃，并且16比特控制信號的精度達(dá)1‰。實(shí)驗結(jié)果表明，這個系統(tǒng)確實(shí)達(dá)到了控制要求，其溫度精度優(yōu)于±0.05℃，實(shí)際應(yīng)用表明這個系統(tǒng)具有實(shí)時性、靈活性、穩(wěn)定的高精度