Design Of NO_x Sensor Controller Based On STM32 MCU

The problem of pollution caused by automobile exhaust emission is becoming more and more serious due to the increasing number of automobiles.Every country in the world is increasing the requirement of automobile exhaust emission.Such as in National ? Standards will be implemented in 2020 take nitrogen oxide(NOx)emissions limits from 60 mg/km down to about 35 mg/km.Subsequently,the detection and control of NOx concentration are challenged.The existing NOx sensors and controllers of diesel vehicles are all produced by Siemens and Continental AG et al.Domestic sensors are few and the sensor probes actually put into use are blank.Due to the long-term technical blockade abroad,the corresponding sensor controller is also very few.So it is urgent to design a sensor controller which can be used in automobile exhaust detection.The research content of this thesis is to design a complete solution of NOx sensor controller which can be used for automobile exhaust detection based on the existing sensor probe.The hardware part of NOx sensor controller is using independently designed hardware circuit instead of the customized chip scheme on which most of the controllers currently used in China.After many experiments,the hardware subtraction circuit was used to the pump voltage output to improve the dynamic response of the system,and STM32 MCU was used as the algorithm platform,a set of control algorithm for the NOx sensor controller was designed for the vehicle environment.In addition,aiming at the nonlinear problem of the controlled model in the auxiliary pump current control,a new PID control strategy was designed to complete the precise control of the existing NOx sensor probe.Combined with the automobile CAN bus,the sensor data and other parameters are output through the CAN bus protocol to self-reliant design of the vehicle NOx sensor controller.In this thesis,the sensor controller is designed without existing foreign custom chip and successfully mat.