电流型NO_(x)传感器加热控制研究与设计

Research and Design of Heating Control for Current Type NO_(x)⁃sensor

为解决电流型NO_(x)传感器因加热控制不当导致的传感器失效,以及温度控制精度低导致传感器测量值不准确的问题,对NO_(x)传感器加热控制策略及加热器特性进行研究,并设计了一种NO_(x)传感器加热控制算法和加热控制电路。首先使用Simulink仿真分析该算法在温度控制中的响应性与稳定性,然后利用COMSOL仿真分析传感器在该算法中长期工作的可靠性,最后基于STM32单片机进行试验验证。结果表明:设计的加热控制算法和电路可以较好满足温度控制要求,传感器冷启动时间约为46 s,温度控制精度为(800±3)℃。温度稳定后传感器活性区域均能达到800℃,YSZ(钇稳定氧化锆)、Al_(2)O_(3)、LSM(镧锶锰)各层最大应力分别为47.1 MPa、50.1 MPa和83.8 MPa,均低于其许用应力。

In order to solve the problems of sensor failure caused by improper heating control of current type NO_(x) sensor and inaccurate measured value caused by low temperature control accuracy,the heating control strategy and heater characteristics of NO_(x) sensor were studied,and a heating control algorithm and heating control circuit of NO_(x) sensor were designed.Simulink was used to simulate and analyze the response and stability of the algorithm in temperature control.COMSOL simulation was used to analyze the reliability of sensor in the algorithm.The test was verified based on STM32 microcontroller.The results show that the designed heating control algorithm and circuit can better meet the temperature control requirements.The cold start time of the sen⁃sor is about 46 s,and the temperature control accuracy is(800±3)℃.After temperature stabilization,the active region of the sen⁃sor can reach 800℃.The maximum stresses of YSZ(yttrium stabilized zirconia),Al2O3 and LSM(lanthanum strontium manga⁃nese)layers are 47.1 MPa,50.1 MPa and 83.8 MPa respectively,which are all lower than their allowable stresses.