A Wide-Range Air-Fuel-Ratio (AFR) control algorithm was developed for production application in Direct Injection Gasoline (DI-G) powertrains. The algorithm controls AFR to a scheduled target by modifying open-loop fuel injection timing duration using a Wide-Range AFR sensor measurement for feedback.
A physically based hybrid State Estimator design was used to account for event-based engine delays and time-based sensor measurement characteristics to determine the error between target and measured AFR. The State Estimator was designed to minimize algorithm size, calibration burden, and engine controller throughput demand. A time based, gain-scheduled Proportional-Integral control algorithm design was used to correct AFR errors.
Non-physical estimation and control functions were designed for application with time-based updates to minimize engine controller throughput demand.
Signal generator capabilities were built into the algorithm to facilitate three-way catalyst perturbation during stoichiometric control, simulate unknown control system disturbances during algorithm calibration, and perform automatic catalyst efficiency sweeps.