光耦輸入接口電路測(cè)試實(shí)驗(yàn)結(jié)果與改進(jìn)方案

1、光耦輸入接口電路測(cè)試實(shí)驗(yàn)結(jié)果與改進(jìn)方案張道勇實(shí)驗(yàn)?zāi)康模和ㄟ^對(duì)某某（不好意思，保密需要，下同）CNC系統(tǒng)輸入電路的研究，擬在不改變電 路的情況下，改變相關(guān)器件參數(shù)值，達(dá)到其它CNC系統(tǒng)輸入電路的性能，以滿足實(shí)際工作要 求。某某CNC系統(tǒng)的現(xiàn)狀：輸入接口在低電平狀態(tài)、高電平狀態(tài)、由低電平到高電平或高 電平向低電平轉(zhuǎn)換、跳變過程中，存在誤關(guān)斷、誤觸發(fā)、誤導(dǎo)通的現(xiàn)象。比如，某某CNC 系統(tǒng)配某某機(jī)床廠某某型號(hào)機(jī)床，用于檢測(cè)主軸變頻器的速度到達(dá)和零速的兩輸入信號(hào)偶爾 出現(xiàn)常有效狀態(tài)；又如：某某機(jī)床廠用接近開關(guān)作為機(jī)床的PC信號(hào)，在常開的狀態(tài)下（未 感應(yīng)到鐵塊時(shí)），接近開關(guān)的輸出端有時(shí)會(huì)有3V至5V的電壓

2、（感性負(fù)載），以至系統(tǒng)一直 處于誤導(dǎo)通（高電平）狀態(tài)。針對(duì)系統(tǒng)個(gè)別情況下，不能穩(wěn)定觸發(fā)、關(guān)斷的現(xiàn)象，做此測(cè)試。給出系統(tǒng)高低電平（跳 變）的電壓范圍，并提出改進(jìn)方案。某某CNC系統(tǒng)測(cè)試數(shù)據(jù):系統(tǒng)輸入模塊原理圖:系統(tǒng)輸入模塊原理分析：目前某某CNC系統(tǒng)的外部輸入接口采用光耦作為隔離輸入器件，用3.3KR/0.5W電阻作 為限流電阻，輸出極采用射級(jí)輸出方式，接RC濾波電路，最后用施密特電路進(jìn)行整型，之 后輸入給系統(tǒng)。光耦是電流敏感型器件，對(duì)外接電壓不敏感，功率噪聲容限大,所以該電路具 有大的輸入電壓范圍，可以用于5V、12V、24V、36V等電壓等級(jí)的信號(hào)輸入，當(dāng)用于24V電 壓等級(jí)的電路時(shí)，工作電

3、流約為7mA，具有比較大的功率噪聲容限。電路整體對(duì)外表現(xiàn)出施 密特特性，即：當(dāng)外部電位由0V上升到約+3.5V以上時(shí)電路由0翻轉(zhuǎn)到1，當(dāng)電壓由高電平 下降時(shí)，在+3.5V處并不翻轉(zhuǎn)回0，而是繼續(xù)下降到約+2.5V時(shí)才翻轉(zhuǎn)回0，這就有效避免了 外部信號(hào)在+3V左右時(shí)，由于噪聲的存在導(dǎo)致輸入信號(hào)發(fā)生震蕩，提高了電壓噪聲容限。詳細(xì)的理論分析與計(jì)算請(qǐng)參見某某CNC系統(tǒng)IO板設(shè)計(jì)說明書。系統(tǒng)測(cè)試數(shù)據(jù):七（高電平）V （低電平）T -R1=3.3K R2=3.6K輸入電壓大于3.3V輸入電壓小于2.5VR1=4.7K R2=3.6K輸入電壓大于4.2V輸入電壓小于3.2VR1=5.1K R2=3.6K輸入

4、電壓大于4.6V輸入電壓小于3.4VR1=3.3K R2=2.0K輸入電壓大于4.4V輸入電壓小于3.3VR1=3.3K R2=1.5K輸入電壓大于5.1V輸入電壓小于3.7VR1=3.3K R2=1.0K（點(diǎn)一）輸入電壓大于6.0V輸入電壓小于4.3VR1=3.6K R2=1.0K（點(diǎn)一）輸入電壓大于6.4V輸入電壓小于4.6VR1=3.9K R2=1.0K（點(diǎn)一）輸入電壓大于6.8V輸入電壓小于5.0VR1=3.3K R2=1.0K（點(diǎn)二）輸入電壓大于6.4V輸入電壓小于4.6VR1=3.6K R2=1.0K（點(diǎn)二）輸入電壓大于6.9V輸入電壓小于5.0VR1=3.9K R2=1.0K（點(diǎn)

5、二）輸入電壓大于7.4V輸入電壓小于5.5V系統(tǒng)測(cè)試數(shù)據(jù)溫度實(shí)驗(yàn):R1=3.3K R2=3.6K10C0C14C七（高電平）輸入電壓大于2.8V輸入電壓大于2.9V輸入電壓大于3.0VV（高電平）T -輸入電壓小于2.2V輸入電壓小于2.3V輸入電壓小于2.4V注：以上數(shù)據(jù)是對(duì)同一個(gè)測(cè)試點(diǎn)多次測(cè)量所得結(jié)果。注：詳細(xì)的測(cè)試數(shù)據(jù)請(qǐng)參閱附表。下同。注：綠色部分是某某CNC系統(tǒng)現(xiàn)在電路阻值。其它部分是改變電阻參數(shù)所測(cè)結(jié)果。其它某某CNC系統(tǒng)測(cè)試數(shù)據(jù):其它某某CNC系統(tǒng)輸入模塊原理圖:+5V其它某某CNC系統(tǒng)測(cè)試數(shù)據(jù)：高電平低電平R1=4.7K R2=1K輸入大于8.6V輸入小于8.6VR1=3.3K

6、R2=1K輸入大于5.6V輸入小于5.6V注1： R1=3.3K R2=1K是刀架信號(hào)（T1、T2T8）電路阻值。第三款CNC系統(tǒng)測(cè)試數(shù)據(jù):第三款CNC輸入模塊原理圖：VDD3. 3R21KVi3K_.I VoR1 1夕TLP181第三款CNC系統(tǒng)測(cè)試數(shù)據(jù):高電平低電平R1=3K， R2=1K輸入大于4.5V輸入小于4.5V第四款CNC系統(tǒng)測(cè)試數(shù)據(jù):高電平低電平輸入大于9.5V輸入小于9.5V注：以上測(cè)試條件是在常溫狀態(tài)下測(cè)得結(jié)果。測(cè)試結(jié)論：某某CNC系統(tǒng)現(xiàn)在電路的V及V電壓較低：在一般情況下，電路的V及V電壓約 T +T -T +T -為+3.3V及+2.5V，而且由于光耦相對(duì)離散性較大，所

7、以該電壓存在個(gè)體差異，當(dāng)外部驅(qū)動(dòng) 電路不能夠可靠的把輸入電壓拉低到+2.5V以下，就可能導(dǎo)致電路不能夠由1（高電平）翻轉(zhuǎn) 到0（低電平）；接近開關(guān)在常閉的狀態(tài)下，有時(shí)會(huì)有3V至5V的電壓輸出（電感負(fù)載，需 考慮溫度影響），此電壓在大于匕+的情況下，將使系統(tǒng)處于誤導(dǎo)通（高電平）狀態(tài)。針對(duì)系統(tǒng)所發(fā)生不能穩(wěn)定觸發(fā)、關(guān)斷現(xiàn)象的原理分析，擬提高系統(tǒng)匕+、Vt-電壓值。在不改動(dòng)輸入模塊原理與PCB板的基礎(chǔ)上，擬采用如下三種方案：增大光耦輸入側(cè)的電阻R1阻值。R1阻值增加，光耦工作電流下降，導(dǎo)致系統(tǒng)抗干擾能 力下降；減小光耦輸出側(cè)的負(fù)載電阻R2,增加光耦的實(shí)際工作電流傳輸比CTR，來提高VT+及VT-， 但

8、采用增加CTR的方式會(huì)導(dǎo)致外部輸入電流不變的情況下，光耦輸出級(jí)Vce將加大，這 會(huì)導(dǎo)致光耦輸出級(jí)整型電路的電壓噪聲容限下降，在不同程度上導(dǎo)致電路的電磁兼容 性指標(biāo)下降，下降的具體情況要根據(jù)光耦負(fù)載電阻的減小情況實(shí)測(cè)而定。更換TLP181。尋找一個(gè)電流傳輸比小一點(diǎn)的光耦。實(shí)驗(yàn)驗(yàn)證周期長(zhǎng)?？紤]用戶5V與24V輸入的兼容性，需首先確定系統(tǒng)匕+、七壓值。當(dāng)某某CNC系統(tǒng)輸 入模塊電阻R1等于3.3K，R2等于2.0K時(shí)，輸入電壓大于4.4V為1（高電平），小于3.3V 為0 （低電平）。不考慮用戶5V與24V輸入的兼容性，需首先確定系統(tǒng)七、匕一壓值。當(dāng)某某CNC系統(tǒng) 輸入模塊電阻R1等于3.9K，R2

9、等于1.0K時(shí)，輸入電壓大于6.8V為1 （高電平），小于5.0V 為0 （低電平）。擬采用此種參數(shù)值生產(chǎn)10臺(tái)系統(tǒng)用于測(cè)試驗(yàn)證。請(qǐng)技術(shù)組及相關(guān)人員共同 確認(rèn)此種方案的可行性。附表:某某CNC系統(tǒng)：表一：R1=3.3K R2=3.6KVi （伏）Vb （伏）Vcc（伏）Vd（伏）If（毫安）Ic（毫安）電流傳輸比0.30.3570.0005.0890.00000.00000.0000.90.8580.0305.0890.01270.00830.6551.20.9330.0485.0890.08090.01330.1651.50.9740.2295.0890.15940.06360.3991.7

10、0.9900.4205.0890.21520.11670.5422.01.0050.7405.0890.30150.20560.6822.51.0211.3475.0890.44820.37420.8352.81.0311.8805.0890.53610.52220.9743.01.0332.0915.0890.59610.58080.9743.21.0382.4475.0890.65520.67971.0383.31.0402.6320.0010.68480.73111.0683.01.0342.2360.0010.59580.62111.0432.71.0281.7270.0010.506

11、70.47970.9472.61.0251.5700.0010.47730.43610.9142.51.0221.4355.0890.44790.39860.890注：紅色字體數(shù)據(jù)表示高低電平跳變時(shí)各測(cè)試點(diǎn)電壓表二：R1=4.7K R2=3.6KVi（伏）Vb （伏）Vcc（伏）Vd（伏）If（毫安）Ic（毫安）電流傳輸比0.30.3560.0005.0890.00000.00000.0000.50.5550.0005.0890.00000.00000.0000.90.8340.0025.0890.01400.00060.0401.10.9060.0165.0890.04130.00440.1

12、081.20.9290.0365.0890.05770.01000.1731.30.9420.0595.0890.07620.01640.2151.50.9620.1265.0890.11450.03500.3061.60.9670.1505.0890.13470.04170.3091.70.9760.2165.0890.15400.06000.3901.80.9820.2765.0890.17400.07670.4411.90.9860.3125.0890.19450.08670.4462.00.9930.4105.0890.21430.11390.5322.10.9940.4455.089

13、0.23530.12360.5252.20.9990.5325.0890.25550.14780.5782.41.0060.6805.0890.29660.18890.6372.51.0090.7625.0890.31720.21170.6672.61.0130.8965.0890.33770.24890.7372.71.0150.9595.0890.35850.26640.7432.81.0181.0765.0890.37910.29890.7882.91.0211.2035.0890.39980.33420.8363.01.0231.2865.0890.42060.35720.8493.2

14、1.0261.4225.0890.46260.39500.8543.31.0281.5185.0890.48340.42170.8723.41.0301.6865.0890.50430.46830.9293.61.0341.8985.0890.54600.52720.9663.71.0341.9695.0890.56720.54690.9643.81.0382.2055.0890.58770.61251.0424.01.0402.4155.0890.62980.67081.0654.11.0412.5245.0890.65090.70111.0774.21.0442.6910.0010.671

15、50.74751.11331.61.1384.9510.0016.48131.37530.2124.11.0392.4570.0010.65130.68251.0483.91.0382.2930.0010.60890.63691.0463.81.0362.1560.0010.58810.59891.0183.71.0342.0160.0010.56720.56000.9873.61.0311.8410.0010.54660.51140.9363.51.0311.8330.0010.52530.50920.9693.41.0281.6750.0010.50470.46530.9223.31.02

16、71.5880.0010.48360.44110.9123.21.0241.4165.0890.46300.39330.850注：紅色字體數(shù)據(jù)表示高低電平跳變時(shí)各測(cè)試點(diǎn)電壓表三：R1=5.1K R2=3.6KVi（伏）Vb （伏）Vcc（伏）Vd（伏）If（毫安）Ic（毫安）電流傳輸比0.30.3320.0005.0890.00000.00000.0000.90.8660.0045.0890.00670.00110.1671.10.9110.0215.0890.03710.00580.1571.30.9320.0465.0890.07220.01280.1771.50.9520.0985.08

17、90.10750.02720.2531.70.9670.1755.0890.14370.04860.3381.80.9760.2375.0890.16160.06580.4072.00.9840.3285.0890.19920.09110.4572.10.9910.4255.0890.21750.11810.5432.30.9970.5415.0890.25550.15030.5882.51.0020.6495.0890.29370.18030.6142.61.0070.7275.0890.31240.20190.6472.81.0110.9435.0890.35080.26190.7473.

18、01.0161.1005.0890.38900.30560.7853.21.0201.2675.0890.42750.35190.8233.41.0241.4835.0890.46590.41190.8843.51.0261.5965.0890.48510.44330.9143.71.0291.7805.0890.52370.49440.9443.81.0311.8995.0890.54290.52750.9724.01.0322.0335.0890.58200.56470.9704.11.0342.1855.0890.60120.60691.0104.21.0362.3345.0890.62

19、040.64831.0454.41.0382.5335.0890.65920.70361.0674.61.0402.7020.0010.69800.75061.0754.51.0412.6790.0010.67820.74421.0974.41.0402.5040.0010.65880.69561.0564.21.0382.3090.0010.62000.64141.0344.11.0362.1860.0010.60080.60721.0114.01.0352.0790.0010.58140.57750.9933.81.0321.9050.0010.54270.52920.9753.71.03

20、11.7670.0010.52330.49080.9383.51.0271.5250.0010.48490.42360.8743.41.0261.5075.0890.46550.41860.899注：紅色字體數(shù)據(jù)表示高低電平跳變時(shí)各測(cè)試點(diǎn)電壓表四：R1=3.3K R2=2KVi （伏）Vb （伏）Vcc（伏）Vd（伏）If（毫安）Ic（毫安）電流傳輸比0.30.2750.0005.0890.00760.00000.0000.90.8790.0035.0890.00640.00150.2361.20.9390.0305.0890.07910.01500.1901.50.9770.1245.089

21、0.15850.06200.3911.70.9930.2245.0890.21420.11200.5232.01.0080.4065.0890.30060.20300.6752.21.0150.5285.0890.35910.26400.7352.31.0180.6025.0890.38850.30100.7752.41.0210.6805.0890.41790.34000.8142.51.0240.7615.0890.44730.38050.8512.61.0280.8735.0890.47640.43650.9162.71.0310.9605.0890.50580.48000.9492.8

22、1.0331.0395.0890.53550.51950.9702.91.0361.1505.0890.56480.57501.0183.01.0381.2655.0890.59450.63251.0643.11.0401.3385.0890.62420.66901.0723.21.0411.4175.0890.65420.70851.0833.31.0441.5475.0890.68360.77351.1313.41.0461.6885.0890.71330.84401.1833.61.0481.8205.0890.77330.91001.1773.71.0511.9945.0890.802

23、70.99701.2423.91.0532.1415.0890.86271.07051.2414.01.0552.3405.0890.89241.17001.3114.11.0552.3765.0890.92271.18801.2874.21.0572.4855.0890.95241.24251.3054.31.0582.6135.0890.98241.30651.3304.41.0592.7070.0011.01241.35351.33731.51.1534.9230.0019.19612.46150.2684.31.0572.6850.0010.98271.34251.3664.21.05

24、62.4890.0010.95271.24451.3064.11.0552.4320.0010.92271.21601.3183.91.0522.1730.0010.86301.08651.2593.61.0481.8530.0010.77330.92651.1983.51.0461.7460.0010.74360.87301.1743.41.0451.6380.0010.71360.81901.1483.31.0411.4835.0890.68450.74151.083注：紅色字體數(shù)據(jù)表示高低電平跳變時(shí)各測(cè)試點(diǎn)電壓表五：R1=3.3K R2=1.5KVi（伏）Vb （伏）Vcc（伏）Vd（伏

25、）If（毫安）Ic（毫安）電流傳輸比0.30.3590.0005.0890.00000.00000.0000.90.8690.0025.0890.00940.00130.1421.20.9410.0245.0890.07850.01600.2041.50.9800.1085.0890.15760.07200.4571.70.9930.1715.0890.21420.11400.5321.91.0020.2445.0890.27210.16270.5982.11.0050.3225.0890.33180.21470.6472.31.0150.4685.0890.38940.31200.8012.

26、41.0180.5015.0890.41880.33400.7982.51.0210.5815.0890.44820.38730.8642.61.0240.6335.0890.47760.42200.8842.71.0280.7155.0890.50670.47670.9412.81.0310.7835.0890.53610.52200.9743.01.0350.9365.0890.59550.62401.0483.21.0391.0675.0890.65480.71131.0863.41.0431.2365.0890.71420.82401.1543.51.0451.3285.0890.74

27、390.88531.1903.61.0461.3665.0890.77390.91071.1773.81.0501.5555.0890.83331.03671.2444.01.0521.7205.0890.89331.14671.2844.21.0551.8955.0890.95301.26331.3264.41.0582.0955.0891.01271.39671.3794.51.0602.2105.0891.04241.47331.4134.61.0612.3005.0891.07241.53331.4304.81.0632.4395.0891.13241.62601.4364.91.06

28、42.5355.0891.16241.69001.4545.01.0652.6105.0891.19241.74001.4595.11.0662.7110.0011.22241.80731.47831.51.1534.8990.0019.19613.26600.3554.91.0622.5430.0011.16301.69531.4584.81.0622.4820.0011.13271.65471.4614.61.0602.2970.0011.07271.53131.4284.51.0592.2090.0011.04271.47271.4124.41.0582.0590.0011.01271.

29、37271.3554.21.0551.8990.0010.95301.26601.3284.01.0521.6980.0010.89331.13201.2673.81.0511.5910.0010.83301.06071.2733.71.0481.4955.0890.80360.99671.240注：紅色字體數(shù)據(jù)表示高低電平跳變時(shí)各測(cè)試點(diǎn)電壓第二款CNC系統(tǒng)：表六：R1=4.7K R2=1KVi（伏）Vo （伏）Vi（伏）Vo（伏）Vi（伏）Vo（伏）備注0.35.0674.13.9418.21.50900.95.0664.23.8948.31.43201.15.0604.33.8158.41

30、.39801.25.0534.43.7488.51.34001.35.0404.63.6478.61.2190電平跳變1.45.0174.73.5938.51.30401.55.0074.93.5221.64.9715.13.4071.74.9615.23.3081.84.9365.43.221.94.9075.53.1552.04.8615.63.0972.14.8385.73.0222.24.7975.82.9742.34.7526.02.8762.44.7266.12.7982.54.6956.22.7392.64.6606.32.6782.74.6166.42.6132.84.5676.52.562.94.5316.62.4713.04.4736.72.4083.24.3877.02.2663.34.3477.12.183.44.2967.32