Design of oxygen sensor heater/element temperature controller.

摘要

The thesis describes the design of an oxygen sensor heater/element temperature controller. The sensor measures oxygen levels in the exhaust gas to enable the closed-loop fuel control algorithm regulate hydrocarbon emission.; The sensing element inside the oxygen sensor requires a minimum operating temperature of 600°C to generate a voltage output as a function of the oxygen level in the exhaust gas. In cold atmospheric conditions and initial start up, the sensor needs a heater to raise the temperature to the required operating temperature. Therefore, a ceramic heater is inserted inside the sensing element of each sensor. During operating conditions when the exhaust gas temperature is above 850°C, the heater temperature exceeds its maximum specification of 1000°C. For this reason, a controller is designed to regulate the temperature of the heater.; This thesis defines the software algorithm and hardware architecture designed to achieve temperature control. The software algorithm design utilizes state feed back control and Kalman filter estimation techniques, while the hardware design applies analog circuit design methodology to interface the oxygen sensor with a microprocessor-based controller. The entire system design is realized using a virtual prototype and tested through computer simulation. Furthermore, the thesis discusses the hardware/software bench tests performed to realize the Mechatronic system design using a rapid prototype tool (dSpace).