光耦输入接口电路测试实验结果与改进方案.doc

光耦输入接口电路测试实验结果与改进方案张道勇 实验目的：通过对某某（不好意思，保密需要，下同）CNC系统输入电路的研究，拟在不改变电路的情况下，改变相关器件参数值，达到其它CNC系统输入电路的性能，以满足实际工作要求。某某CNC系统的现状：输入接口在低电平状态、高电平状态、由低电平到高电平或高电平向低电平转换、跳变过程中，存在误关断、误触发、误导通的现象。比如，某某CNC系统配某某机床厂某某型号机床，用于检测主轴变频器的速度到达和零速的两输入信号偶尔出现常有效状态；又如：某某机床厂用接近开关作为机床的PC信号，在常开的状态下（未感应到铁块时），接近开关的输出端有时会有3V至5V的电压（感性负载），以至系统一直处于误导通（高电平）状态。针对系统个别情况下，不能稳定触发、关断的现象，做此测试。给出系统高低电平（跳变）的电压范围，并提出改进方案。某某CNC系统测试数据：系统输入模块原理图：系统输入模块原理分析：目前某某CNC系统的外部输入接口采用光耦作为隔离输入器件，用3.3KR/0.5W电阻作为限流电阻，输出极采用射级输出方式，接RC滤波电路，最后用施密特电路进行整型，之后输入给系统。光耦是电流敏感型器件,对外接电压不敏感,功率噪声容限大,所以该电路具有大的输入电压范围,可以用于5V、12V、24V、36V等电压等级的信号输入，当用于24V电压等级的电路时，工作电流约为7mA，具有比较大的功率噪声容限。电路整体对外表现出施密特特性，即：当外部电位由0V上升到约+3.5V以上时电路由0翻转到1，当电压由高电平下降时，在+3.5V处并不翻转回0，而是继续下降到约+2.5V时才翻转回0，这就有效避免了外部信号在+3V左右时，由于噪声的存在导致输入信号发生震荡，提高了电压噪声容限。详细的理论分析与计算请参见某某CNC系统IO板设计说明书。系统测试数据：(高电平)（低电平）R1=3.3KR2=3.6K输入电压大于3.3V输入电压小于2.5VR1=4.7KR2=3.6K输入电压大于4.2V输入电压小于3.2VR1=5.1KR2=3.6K输入电压大于4.6V输入电压小于3.4VR1=3.3KR2=2.0K输入电压大于4.4V输入电压小于3.3VR1=3.3K R2=1.5K输入电压大于5.1V输入电压小于3.7VR1=3.3K R2=1.0K(点一)输入电压大于6.0V输入电压小于4.3VR1=3.6K R2=1.0K(点一)输入电压大于6.4V输入电压小于4.6VR1=3.9K R2=1.0K(点一)输入电压大于6.8V输入电压小于5.0VR1=3.3K R2=1.0K(点二)输入电压大于6.4V输入电压小于4.6VR1=3.6K R2=1.0K(点二)输入电压大于6.9V输入电压小于5.0VR1=3.9K R2=1.0K(点二)输入电压大于7.4V输入电压小于5.5V系统测试数据温度实验：R1=3.3KR2=3.6K10014(高电平)输入电压大于2.8V输入电压大于2.9V输入电压大于3.0V(高电平)输入电压小于2.2V输入电压小于2.3V输入电压小于2.4V注：以上数据是对同一个测试点多次测量所得结果。注：详细的测试数据请参阅附表。下同。注：绿色部分是某某CNC系统现在电路阻值。其它部分是改变电阻参数所测结果。其它某某CNC系统测试数据：其它某某CNC系统输入模块原理图：其它某某CNC系统测试数据：高电平低电平R1=4.7K R2=1K输入大于8.6V输入小于8.6VR1=3.3K R2=1K输入大于5.6V输入小于5.6V注1：R1=3.3KR2=1K是刀架信号（T1、T2T8）电路阻值。第三款CNC系统测试数据：第三款CNC输入模块原理图：第三款CNC系统测试数据：高电平低电平R1=3K，R2=1K输入大于4.5V输入小于4.5V第四款CNC系统测试数据：高电平低电平输入大于9.5V输入小于9.5V注：以上测试条件是在常温状态下测得结果。测试结论：某某CNC系统现在电路的及电压较低：在一般情况下，电路的及电压约为+3.3V及+2.5V，而且由于光耦相对离散性较大，所以该电压存在个体差异，当外部驱动电路不能够可靠的把输入电压拉低到+2.5V以下，就可能导致电路不能够由1(高电平)翻转到0（低电平）；接近开关在常闭的状态下，有时会有3V至5V的电压输出（电感负载，需考虑温度影响），此电压在大于的情况下，将使系统处于误导通（高电平）状态。针对系统所发生不能稳定触发、关断现象的原理分析，拟提高系统、电压值。在不改动输入模块原理与PCB板的基础上，拟采用如下三种方案：增大光耦输入侧的电阻R1阻值。R1阻值增加，光耦工作电流下降，导致系统抗干扰能力下降；减小光耦输出侧的负载电阻R2，增加光耦的实际工作电流传输比CTR，来提高VT+及VT-，但采用增加CTR的方式会导致外部输入电流不变的情况下，光耦输出级Vce将加大, 这会导致光耦输出级整型电路的电压噪声容限下降, 在不同程度上导致电路的电磁兼容性指标下降，下降的具体情况要根据光耦负载电阻的减小情况实测而定。更换TLP181。寻找一个电流传输比小一点的光耦。实验验证周期长。考虑用户5V与24V输入的兼容性，需首先确定系统、压值。当某某CNC系统输入模块电阻R1等于3.3K，R2等于2.0K时，输入电压大于4.4V为1（高电平），小于3.3V为0（低电平）。不考虑用户5V与24V输入的兼容性，需首先确定系统、压值。当某某CNC系统输入模块电阻R1等于3.9K，R2等于1.0K时，输入电压大于6.8V为1（高电平），小于5.0V为0（低电平）。拟采用此种参数值生产10台系统用于测试验证。请技术组及相关人员共同确认此种方案的可行性。附表：某某CNC系统：表一:R1=3.3KR2=3.6KVi（伏）Vb（伏）Vcc(伏)Vd(伏)If(毫安)Ic(毫安)电流传输比0.30.3570.0005.0890.00000.00000.0000.90.8580.0305.0890.01270.00830.6551.20.9330.0485.0890.08090.01330.1651.50.9740.2295.0890.15940.06360.3991.70.9900.4205.0890.21520.11670.5422.01.0050.7405.0890.30150.20560.6822.51.0211.3475.0890.44820.37420.8352.81.0311.8805.0890.53610.52220.9743.01.0332.0915.0890.59610.58080.9743.21.0382.4475.0890.65520.67971.0383.31.0402.6320.0010.68480.73111.0683.01.0342.2360.0010.59580.62111.0432.71.0281.7270.0010.50670.47970.9472.61.0251.5700.0010.47730.43610.9142.51.0221.4355.0890.44790.39860.890注：红色字体数据表示高低电平跳变时各测试点电压表二:R1=4.7KR2=3.6KVi（伏）Vb（伏）Vcc(伏)Vd(伏)If(毫安)Ic(毫安)电流传输比0.30.3560.0005.0890.00000.00000.0000.50.5550.0005.0890.00000.00000.0000.90.8340.0025.0890.01400.00060.0401.10.9060.0165.0890.04130.00440.1081.20.9290.0365.0890.05770.01000.1731.30.9420.0595.0890.07620.01640.2151.50.9620.1265.0890.11450.03500.3061.60.9670.1505.0890.13470.04170.3091.70.9760.2165.0890.15400.06000.3901.80.9820.2765.0890.17400.07670.4411.90.9860.3125.0890.19450.08670.4462.00.9930.4105.0890.21430.11390.5322.10.9940.4455.0890.23530.12360.5252.20.9990.5325.0890.25550.14780.5782.41.0060.6805.0890.29660.18890.6372.51.0090.7625.0890.31720.21170.6672.61.0130.8965.0890.33770.24890.7372.71.0150.9595.0890.35850.26640.7432.81.0181.0765.0890.37910.29890.7882.91.0211.2035.0890.39980.33420.8363.01.0231.2865.0890.42060.35720.8493.21.0261.4225.0890.46260.39500.8543.31.0281.5185.0890.48340.42170.8723.41.0301.6865.0890.50430.46830.9293.61.0341.8985.0890.54600.52720.9663.71.0341.9695.0890.56720.54690.9643.81.0382.2055.0890.58770.61251.0424.01.0402.4155.0890.62980.67081.0654.11.0412.5245.0890.65090.70111.0774.21.0442.6910.0010.67150.74751.11331.61.1384.9510.0016.48131.37530.2124.11.0392.4570.0010.65130.68251.0483.91.0382.2930.0010.60890.63691.0463.81.0362.1560.0010.58810.59891.0183.71.0342.0160.0010.56720.56000.9873.61.0311.8410.0010.54660.51140.9363.51.0311.8330.0010.52530.50920.9693.41.0281.6750.0010.50470.46530.9223.31.0271.5880.0010.48360.44110.9123.21.0241.4165.0890.46300.39330.850注：红色字体数据表示高低电平跳变时各测试点电压表三:R1=5.1KR2=3.6KVi（伏）Vb（伏）Vcc(伏)Vd(伏)If(毫安)Ic(毫安)电流传输比0.30.3320.0005.0890.00000.00000.0000.90.8660.0045.0890.00670.00110.1671.10.9110.0215.0890.03710.00580.1571.30.9320.0465.0890.07220.01280.1771.50.9520.0985.0890.10750.02720.2531.70.9670.1755.0890.14370.04860.3381.80.9760.2375.0890.16160.06580.4072.00.9840.3285.0890.19920.09110.4572.10.9910.4255.0890.21750.11810.5432.30.9970.5415.0890.25550.15030.5882.51.0020.6495.0890.29370.18030.6142.61.0070.7275.0890.31240.20190.6472.81.0110.9435.0890.35080.26190.7473.01.0161.1005.0890.38900.30560.7853.21.0201.2675.0890.42750.35190.8233.41.0241.4835.0890.46590.41190.8843.51.0261.5965.0890.48510.44330.9143.71.0291.7805.0890.52370.49440.9443.81.0311.8995.0890.54290.52750.9724.01.0322.0335.0890.58200.56470.9704.11.0342.1855.0890.60120.60691.0104.21.0362.3345.0890.62040.64831.0454.41.0382.5335.0890.65920.70361.0674.61.0402.7020.0010.69800.75061.0754.51.0412.6790.0010.67820.74421.0974.41.0402.5040.0010.65880.69561.0564.21.0382.3090.0010.62000.64141.0344.11.0362.1860.0010.60080.60721.0114.01.0352.0790.0010.58140.57750.9933.81.0321.9050.0010.54270.52920.9753.71.0311.7670.0010.52330.49080.9383.51.0271.5250.0010.48490.42360.8743.41.0261.5075.0890.46550.41860.899注：红色字体数据表示高低电平跳变时各测试点电压表四:R1=3.3KR2=2KVi（伏）Vb（伏）Vcc(伏)Vd(伏)If(毫安)Ic(毫安)电流传输比0.30.2750.0005.0890.00760.00000.0000.90.8790.0035.0890.00640.00150.2361.20.9390.0305.0890.07910.01500.1901.50.9770.1245.0890.15850.06200.3911.70.9930.2245.0890.21420.11200.5232.01.0080.4065.0890.30060.20300.6752.21.0150.5285.0890.35910.26400.7352.31.0180.6025.0890.38850.30100.7752.41.0210.6805.0890.41790.34000.8142.51.0240.7615.0890.44730.38050.8512.61.0280.8735.0890.47640.43650.9162.71.0310.9605.0890.50580.48000.9492.81.0331.0395.0890.53550.51950.9702.91.0361.1505.0890.56480.57501.0183.01.0381.2655.0890.59450.63251.0643.11.0401.3385.0890.62420.66901.0723.21.0411.4175.0890.65420.70851.0833.31.0441.5475.0890.68360.77351.1313.41.0461.6885.0890.71330.84401.1833.61.0481.8205.0890.77330.91001.1773.71.0511.9945.0890.80270.99701.2423.91.0532.1415.0890.86271.07051.2414.01.0552.3405.0890.89241.17001.3114.11.0552.3765.0890.92271.18801.2874.21.0572.4855.0890.95241.24251.3054.31.0582.6135.0890.98241.30651.3304.41.0592.7070.0011.01241.35351.33731.51.1534.9230.0019.19612.46150.2684.31.0572.6850.0010.98271.34251.3664.21.0562.4890.0010.95271.24451.3064.11.0552.4320.0010.92271.21601.3183.91.0522.1730.0010.86301.08651.2593.61.0481.8530.0010.77330.92651.1983.51.0461.7460.0010.74360.87301.1743.41.0451.6380.0010.71360.81901.1483.31.0411.4835.0890.68450.74151.083注：红色字体数据表示高低电平跳变时各测试点电压表五:R1=3.3KR2=1.5KVi（伏）Vb（伏）Vcc(伏)Vd(伏)If(毫安)Ic(毫安)电流传输比0.30.3590.0005.0890.00000.00000.0000.90.8690.0025.0890.00940.00130.1421.20.9410.0245.0890.07850.01600.2041.50.9800.1085.0890.15760.07200.4571.70.9930.1715.0890.21420.11400.5321.91.0020.2445.0890.27210.16270.5982.11.0050.3225.0890.33180.21470.6472.31.0150.4685.0890.38940.31200.8012.41.0180.5015.0890.41880.33400.7982.51.0210.5815.0890.44820.38730.8642.61.0240.6335.0890.47760.42200.8842.71.0280.7155.0890.50670.47670.9412.81.0310.7835.0890.53610.52200.9743.01.0350.9365.0890.59550.62401.0483.21.0391.0675.0890.65480.71131.0863.41.0431.2365.0890.71420.82401.1543.51.0451.3285.0890.74390.88531.1903.61.0461.3665.0890.77390.91071.1773.81.0501.5555.0890.83331.03671.2444.01.0521.7205.0890.89331.14671.2844.21.0551.8955.0890.95301.26331.3264.41.0582.0955.0891.01271.39671.3794.51.0602.2105.0891.04241.47331.4134.61.0612.3005.0891.07241.53331.4304.81.0632.4395.0891.13241.62601.4364.91.0642.5355.0891.16241.69001.4545.01.0652.6105.0891.19241.74001.4595.11.0662.7110.0011.22241.80731.47831.51.1534.8990.0019.19613.26600.3554.91.0622.5430.0011.16301.69531.4584.81.0622.4820.0011.13271.65471.4614.61.0602.2970.0011.07271.53131.4284.51.0592.2090.0011.04271.47271.4124.41.0582.0590.0011.01271.37271.3554.21.0551.8990.0010.95301.26601.3284.01.0521.6980.0010.89331.13201.2673.81.0511.5910.0010.83301.06071.2733.71.0481.4955.0890.80360.99671.240注：红色字体数据表示高低电平跳变时各测试点电压第二款CNC系统：表六:R1=4.7KR2=1KVi（伏）Vo（伏）Vi(伏)Vo(伏)Vi(伏)Vo(伏)备注0.35.0674.13.9418.21.50900.95.0664.23.8948.31.43201.15.0604.33.8158.41.39801.25.0534.43.7488.51.34001.35.0404.63.6478.61.2190电平跳变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