introductionstotemperaturecontrol(溫度控制簡(jiǎn)介和pid控制器外文翻譯-免費(fèi)閱讀
【正文】 比如，讓我們拿烤爐的加熱為例。當(dāng)然這個(gè)想法是有意義的。典型的例子就是調(diào)整你的烤爐在合適的溫度。如果 PV和 SP之間偏差小 —— 那我們就在輸出時(shí)作一個(gè)小的改變。 我們注意到輸出量經(jīng)常超過穩(wěn)定狀態(tài)輸出使過程變量回到基準(zhǔn)點(diǎn)。如果你有一個(gè) PID控制的可進(jìn)入的冷凍裝置，某個(gè)人打開門進(jìn)入，溫度 (過程變量 )將會(huì)迅速升高。 PID 控制器的任務(wù)是維持輸出在一個(gè)程度上，這樣在過程變量 (PV)和基準(zhǔn)點(diǎn)(SP)上就沒有偏差 (誤差 )。還有其他的假定。如果基準(zhǔn)點(diǎn)升高， PID 控制器就會(huì)自動(dòng)的增加加熱器中氣體的流量。例如：控制一個(gè)容器的熱量。 (2)變送器，也稱二次元件。 為達(dá)到上述目標(biāo)，就 需要設(shè)計(jì)并實(shí)現(xiàn)一個(gè)系統(tǒng)。 實(shí)現(xiàn)該目的的一種方 法是首先測(cè)量 r(0，然后與期望值相比較，由比較結(jié)果決定如何校正偏差。變化總是會(huì)出現(xiàn)，此時(shí)如果不采取相應(yīng)的措施，那些與安全、產(chǎn)品 質(zhì)量和生產(chǎn)率有關(guān)的重要變量就不能滿足設(shè)計(jì)要求。s think about how to design a PID controller. We focus on the difference (error) between the process variable (PV) and the setpoint (SP). There are three ways we can view the error. The absolute error This means how big is the difference between the PV and SP. If there is a small difference between the PV and the SPthen let39。 heating thermostats. In contrast, the PID controller would receive input as the actual temperature and control a valve that regulates the flow of gas to the heater. The PID controller automatically finds the correct (constant) flow of gas to the heater that keeps the temperature steady at the setpoint. Instead of the temperature bouncing back and forth between two points, the temperature is held steady. If the setpoint is lowered, then the PID controller automatically reduces the amount of gas flowing to the heater. If the setpoint is raised, then the PID controller automatically increases the amount of gas flowing to the heater. Likewise the PID controller would automatically for hot, sunny days (when it is hotter outside the heater) and for cold, cloudy days. The analog input (measurement) is called the process variable or PV. You want the PV to be a highly accurate indication of the process parameter you are trying to control. For example, if you want to maintain a temperature of + or one degree then we typically strive for at least ten times that or onetenth of a degree. If the analog input is a 12 bit analog input and the temperature range for the sensor is 0 to 400 degrees then our theoretical accuracy is calculated to be 400 degrees divided by 4,096 (12 bits) = degrees. [~] We say theoretical because it would assume there was no noise and error in our temperature sensor, wiring, and analog converter. There are other assumptions such as linearity, etc.. The point beingwith 1/10 of a degree theoretical accuracyeven with the usual amount of noise and other problems one degree of accuracy should easily be attainable. The analog output is often simply referred to as output. Often this is given as 0~100 percent. In this heating example, it would mean the valve is totally closed (0%) or totally open (100%). The setpoint (SP) is simplywhat process value do you want. In this examplewhat temperature do you want the process at? The PID controller39。s take heating of the oven. simulation chart If we start turning up the gas flow, it will take time for the heat to be produced, the heat to flow around the oven, and for the temperature sensor to detect the increased heat. Derivative control sort of holds back the PID controller because some increase in temperature will occur without needing to increase the output further. Setting the derivative constant correctly allows you to bee more aggressive with the P amp。 只要周圍沒有熱損耗，過程流體獲得的熱量就等于蒸汽釋放的熱量，即熱交換器和管道間的隔熱性很好。因此，我們想自動(dòng)完成這種控制。根據(jù)比較的結(jié)果，控制器確定保持溫度為期望值的控制作用。 (2)決策：根據(jù)測(cè)量結(jié)果，為了維持輸出為期望值，控制器必須決定如何操作。 PID 控制器自動(dòng)地找到加熱器中氣體的合適流量，這樣就保持了溫度在基準(zhǔn)點(diǎn)穩(wěn)定。例如，如果我們想要保持溫度為 +1 度或 — 1度，我們至少要為此努力，使其 精度保持在 0． 1度。在這個(gè)熱量的例子中閥門完全關(guān)閉 (0％ )，完全打開 (100％ )。PV 和 SP 之間偏差大還是小。 這樣就有了兩個(gè)矛盾的目標(biāo)。 我們主要集中在過程變量 (PV)和基準(zhǔn)點(diǎn) (SP)之間的偏差 (誤差 )上。每次我們運(yùn)行
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