A phase and frequency locking loop for engine air-fuel ratio control

In the spirit of the recent articles in [5], featuring classical controls revisited, a phase-lock loop concept is applied to an automotive air-fuel ratio closed-loop control system. This classical solution is analyzed, simulated, and experimentally implemented in a vehicle. The results demonstrate that the automobile engine air-fuel ratio system can be controlled to robustly meet emissions and driving performance requirements by using a simple classical control methodology with feedback from the common switching oxygen sensor.