【正文】 的應(yīng)用在本系統(tǒng)中,執(zhí)行機(jī)構(gòu)滑差電機(jī)的轉(zhuǎn)速可由經(jīng)DAC0832輸出的控制電流來(lái)調(diào)節(jié),從而實(shí)現(xiàn)對(duì)皮帶上物料的流量控制。：（1）分辨率8位；（2）電流穩(wěn)定時(shí)間1us；（3）可單緩沖、雙緩沖或直接數(shù)字輸入；（4）只需在滿量程下調(diào)整其線性度；（5）單一電源供電（+5V～+15V）；（6）低功耗，20mW。（7）IOUT1：電流輸出端1，其值隨DAC寄存器的內(nèi)容線性變化；（8）IOUT2：電流輸出端2，其值與IOUT1值之和為一常數(shù)；（9）Rfb：反饋信號(hào)輸入線，改變Rfb端外接電阻值可調(diào)整轉(zhuǎn)換滿量程精度；（10）Vcc：電源輸入端，Vcc的范圍為+5V～+15V；（11）VREF：基準(zhǔn)電壓輸入線，VREF的范圍為10V～+10V；（12）AGND：模擬信號(hào)地；（13）DGND：數(shù)字信號(hào)地。本系統(tǒng)DAC0832工作于單緩沖方式，只用輸入寄存器鎖存數(shù)據(jù)。 電機(jī)調(diào)速控制電路在晶體管功率放大和電源電路中，脈沖寬度調(diào)制器以其功耗低、效率高得到了廣泛的應(yīng)用。單相橋式PWM逆變電路如圖39所示。異步電機(jī)作為原動(dòng)機(jī)使用，當(dāng)它旋轉(zhuǎn)時(shí)帶動(dòng)離合器的電樞一起旋轉(zhuǎn)，電氣控制裝置是提供滑差離合器勵(lì)磁線圈勵(lì)磁電流的裝置。當(dāng)勵(lì)磁線圈通過(guò)電流時(shí)產(chǎn)生磁場(chǎng)，爪形結(jié)構(gòu)便形成很多對(duì)磁極。在電子電路及設(shè)備中，一般都需要穩(wěn)定的直流電源供電。在整流、濾波電路之后，還須接穩(wěn)壓電路，保證輸出的直流電壓穩(wěn)定。所以變壓器將220V交流電壓變換成符合需要的交流電壓，然后送給整流電路。這種整流電路使用普通的變壓器，但是比全波整流多用了兩個(gè)整流二極管。之所以使用電容濾波電路是利用電容的充放電原理來(lái)達(dá)到濾波的作用。其作用是當(dāng)交流電網(wǎng)電壓波動(dòng)或負(fù)載變化時(shí)，保證輸出直流電壓的穩(wěn)定。常用的集成穩(wěn)壓器有三端固定集成穩(wěn)壓器和三端可調(diào)集成穩(wěn)壓器，它們都屬于電壓串聯(lián)反饋型。圖312：系統(tǒng)閉環(huán)控制回路原理圖當(dāng)輸送皮帶以運(yùn)作時(shí)，物料在皮帶上一般為不均勻分布，瞬時(shí)流量為： （34）式中：P(t)為單位長(zhǎng)度上物料的瞬時(shí)重量； V(t)為皮帶的瞬時(shí)線速度。在流量測(cè)試的基礎(chǔ)上，把流量設(shè)定值和實(shí)際測(cè)試得到的瞬時(shí)流量進(jìn)行比較，計(jì)算出誤差。 輸出控制變量Vi的表達(dá)式為： （38）式中：為上一時(shí)刻輸出的控制變量。依據(jù)系統(tǒng)功能，可以將軟件部分劃分為若干個(gè)功能相對(duì)獨(dú)立的模塊，然后為每一個(gè)模塊設(shè)計(jì)算法并規(guī)劃出程序流程圖，再根據(jù)流程圖編寫程序。系統(tǒng)初始化的主要任務(wù)是在程序開始運(yùn)行時(shí)，對(duì)控制系統(tǒng)中所用到的各個(gè)串行口、地址和定時(shí)器的工作方式進(jìn)行初始化設(shè)定，同時(shí)對(duì)用戶地址進(jìn)行計(jì)算規(guī)劃。鍵盤掃描流程圖如圖41。，則由逐列掃描找出這個(gè)鍵的所在位置。依照這種方法逐次掃描各列直到找到為0的行輸出為止。，說(shuō)明按下的是功能鍵，則通過(guò)散轉(zhuǎn)程序轉(zhuǎn)到各自的入口地址，分別實(shí)現(xiàn)各自的功能。當(dāng)?shù)谝粋€(gè)鍵按下時(shí)，讓程序執(zhí)行一段除最右邊LED顯示外其余均熄滅的程序，即給其他緩沖區(qū)送入一個(gè)數(shù)，使它查表后得到的段碼為00H，則其他數(shù)碼管不亮，該程序?yàn)镈ISP1。WR鍵的功能為輸入流量設(shè)定值或PID調(diào)節(jié)及線性公式中的系數(shù)(P、I、D、a、b、c、d)。同理，也應(yīng)將4位數(shù)據(jù)壓縮為兩個(gè)字節(jié)的壓縮BCD碼備用。按下此鍵流量設(shè)定值先顯示出來(lái)，如需要改變?cè)O(shè)定值，則用鍵盤敲入相應(yīng)的數(shù)字鍵，隨后按下WR鍵即可。然后返回鍵掃描程序，這樣就可以退出命令狀態(tài)，執(zhí)行清標(biāo)志位功能，等待新命令的輸入。按下此鍵，先啟動(dòng)輸送皮帶空轉(zhuǎn)運(yùn)動(dòng)，然后啟動(dòng)A/D轉(zhuǎn)換器對(duì)荷重傳感器的輸出信號(hào)進(jìn)行轉(zhuǎn)換，取若干次結(jié)果的平均值作為皮帶的自重，寫入相應(yīng)單元保存。在本設(shè)計(jì)中，DAC0832的地址為C000H。在本系統(tǒng)中，首先要判別是否已輸入過(guò)設(shè)定值，若沒(méi)有輸入過(guò)，則應(yīng)跳回鍵掃描。因?yàn)樵撓到y(tǒng)任務(wù)單一，CPU只需順序進(jìn)行采樣、計(jì)算、控制輸出、顯示等任務(wù)，各任務(wù)之間無(wú)時(shí)序上的沖突，故不用采用中斷處理。根據(jù)定時(shí)器中的值可計(jì)算INT1引腳上出現(xiàn)的正脈沖寬度。在計(jì)算時(shí)，用公式計(jì)算轉(zhuǎn)速。故TMOD＝10010000B，即在初始化時(shí)TMOD將置為90H。 本設(shè)計(jì)的計(jì)算主要有兩部分：一是計(jì)算瞬時(shí)流量，二是通過(guò)PID調(diào)節(jié)程序計(jì)算輸出控制變量。 顯示程序顯示程序用于顯示計(jì)算出來(lái)的瞬時(shí)流量F(t)，它主要是用一個(gè)取整子程序，使瞬時(shí)流量F(t)轉(zhuǎn)換成二進(jìn)制數(shù)，并取出16位的整數(shù)絕對(duì)值和16位的小數(shù)部分，調(diào)用雙字節(jié)二進(jìn)制整數(shù)轉(zhuǎn)換成十進(jìn)制整數(shù)的子程序和雙字節(jié)二進(jìn)制小數(shù)轉(zhuǎn)換為十進(jìn)制小數(shù)的子程序，分別將數(shù)據(jù)轉(zhuǎn)化為十進(jìn)制，并將整數(shù)部分送給45H、44H單元，小數(shù)部分送入42H、41H、40H單元，43H單元送入0AH，即段碼80H，用于顯示小數(shù)點(diǎn)“．”。由硬件電路可知，從而使揚(yáng)聲器發(fā)聲。該系統(tǒng)的設(shè)計(jì)可以比較完善的自動(dòng)處理工作中出現(xiàn)的異常狀況，實(shí)現(xiàn)了漏料、缺料、原料不足等異常情況的自動(dòng)報(bào)警，此系統(tǒng)操作非常簡(jiǎn)單，使用性能好，抗干擾能力強(qiáng)，而且不容易出現(xiàn)故障，非常適合工作人員的操作，現(xiàn)今在中國(guó)中、小型企業(yè)應(yīng)用最為廣泛。當(dāng)然此系統(tǒng)還有很多不足和待開發(fā)的地方。參考文獻(xiàn)[1] [M].北京：中國(guó)電力出版社，[2] 李國(guó)興,[M].杭州：浙江大學(xué)出版社，[3] 張齊,[M].北京：電子工業(yè)出版社，[4] 楊打生,[M].北京：北京理工大學(xué)出版社，[5] 肖軍,[M].北京：機(jī)械工業(yè)出版社，[6] [M].西安：西安電子科技大學(xué)出版社，[7] 殷剛，[M].北京：北京理工大學(xué)出版社，[8] [M].西安:西安電子出版社，1999[9] [M].北京:高等教育出版社，2004[10] [M].北京:高等教育出版社，2008[11] （第二版）[M].北京:清華大學(xué)出版社，2004[12] Tshilidzi monitoring using putational intelligence methods : applications in mechanical and electrical systems [M].ERT press,2012[13] Soliman Abdelhady Soliman,Ahmad . Electrical load forecasting modeling and model construction [M].Dream Gateway Inc,2010外文原文和譯文Application NoteSensorless Brushless DC MotorControl with Z8 Encore! MCTMMicrocontrollersAbstractThis application note discusses the closed loop control of a 3Phase Brushless Direct Current (BLDC) motor using the Z8 Encore! MC? family of Microcontrollers (MCUs). The Z8 Encore! MC? product family is designed specifically for motor control applications, featuring an onchip integrated array of application specific analog and digital modules. This in turn results in fast and precise fault control, high system efficiency, and onthefly speed/torque and direction control, as well as ease of firmware development for customized applications.This article further discusses ways on how to implement a sensorless feedback control system using a Phase Locked Loop along with Back EMF sensing. Test results are based on using the Zilog BLDC Motor Control Development kit Z8FMC160100KITG. This development kit includes a Motor Control Motor Drive System module with a 32pin Z8FMC16100 MCU, a 3Phase Motor Control Application Board and a 3phase 24 VDC, 30W, 3200RPM BLDC motor with Internal Hall Sensors.Note: This application note was tested with version of ZDS II. Subsequent releases of ZDS II might require you to modify code supplied with this application note.FeaturesThe key features of this reference design include:? Smooth Scurve motor startup with reduced starting current? Sensorless (BackEMF) control using Phase Locked Loop feedback? Microcontrollerbased overcurrent protection? Selectable Speed or Torque Setting? Selectable Speed or Torque Control? Selectable control of motor direction? LED for max speed indication? LED for motoring running indication? LED for Fault indicationDiscussionThe use of BLDC motors has steadily increased over the last several years as the cost of these motors and the technology to control these motors has decreased and the benefits of these motors over other motor types has bee more important than just the initial cost. Variable speed motor applications in industries such as White Goods, Automotive, Aerospace, Medical, and Industrial Automation are now using the BLDC motor over other types of motors, such as Brushed DC and AC Induction.The construction of a BLDC motor gives it several advantages when pared to other electric motors. First, since the BLDC uses electronic mutation it has a longer life when pared with brushed DC motors and requires less maintenance since the brushes on the motor do not require cleaning and replacement. They also run much quieter, both electrically and audibly, because the motor does not have brush arcing and the mechanical mutation of other types of motors. A BLDC motor will generally have a higher output per frame size since the windings are connected to the stator and the heat generated from running can be transferred directly to the motor housing allowing cooler operation. Finally, a BLDC motor will have much lower electrical and friction losses because they don’t need to transfer power from the brushes. These losses are most prevalent at lower loads. The data has shown that a standard BLDC motor will have 510% better efficiency than