NO x 传感器的氧补偿及其标定策略

针对氧化锆基氮氧化物传感器信号受汽车尾气氧含量影响，导致精度不佳问题，提出一种氧补偿算法和标定策略。根据NO_x传感器工作原理进行模拟试验，分析不同氧含量下泵电流I_P2与NO_x浓度的关系，得出氧补偿算法，并分析了氧含量与补偿系数的关系，设计出一种实时对I_P2误差补偿的方案，使I_P2在氧含量为0%～20%,NO_x为0～3 000×10^-6范围内的误差减小到23 nA,对应NO_x浓度误差降低到15×10^-6以内。为进一步提高传感器测量的准确度，设计了一套标定方案，并与国外NO_x传感器进行对比测试。结果表明，该传感器在发动机瞬态工况下，NO_x浓度为0～2 000×10^-6的环境中，测量误差为0～25×10^-6,验证了该方案的可行性，满足尾气中NO_x浓度的监测要求，为提高氧化锆基NO_...

Oxygen compensation of the NOx sensor and its calibration strategy

An oxygen compensation algorithm and calibration strategy are proposed to address the problem that the zirconia-based NOx sensor signal is affected by the oxygen content of vehicle exhaust, which may result in poor accuracy. A simulation test is conducted according to the working principle of the NOx sensor, the relationship between pump current IP2 and NOx concentration at different oxygen content is analyzed. The oxygen compensation algorithm is derived, and the relationship between oxygen content and compensation coefficient is analyzed. A real-time compensation scheme for IP2 error is designed. Consequently, the error of IP2 in the range of oxygen content from 0% ~ 20% and NOx from 0~ 3 000×10 -6 is reduced to 23 nA, and the Corresponding NOx concentration error is reduced to within 15×10 -6 . To further improve the accuracy of the sensor measurement, a calibration scheme is designed and tested in comparison with foreign NOx sensors. The results show that the sensor has a measurement error of 0~25×10 -6 in an environment with NOx concentration of 0~2 000×10 -6 under transient engine conditions, which verifies the feasibility of the scheme and well meets the requirements for monitoring NOx concentration in the exhaust gas, and provides a reliable solution for improving the accuracy of zirconia-based NOx sensors.