According to characteristics of LSU 4. 9 universal exhaust gas oxygen sensor and set STM32 as implementation platform of the control algorithm

design of air-fuel ratio analyzer is carried out and realized. In hardware aspect

based on negative temperature coefficient（ NTC） characteristic of universal exhaust gas oxygen sensor

an internal resistance measurement method based on AC comparison means is proposed which helps to control the temperature of oxygen sensor. Not only eliminate influence of differences in multi-channel measurement circuit. In terms of software

considering perturbation of pump current

proportion integration differentiation neural network（ PIDNN） algorithm is

proposed to realize feedback control of the oxygen sensor. Experiments show that the designed air-fuel ratio analyzer can meet the requirements of fast start-up

and can achieve accurate measurement in the range of 0

12. 1 % oxygen concentration

it has short dynamic response time

and can keep track of the change of oxygen concentration.