Adaptive air-fuel ratio control for hydrogen internal combustion engines

In the global effort to reduce CO 2 emissions, hydrogen is considered as a promising energy carrier for mobile applications. This study focuses on turbocharged hydrogen internal combustion engines operating in lean conditions. It requires high air flow and consequently leads to significant delays in torque response. A dedicated control architecture is proposed to reduce this delay while maintaining combustion stability and limiting nitrogen oxide (NO x ) emissions. The approach primarily exploits fuel quantity as the main degree of freedom to improve transient torque response and support turbocharger dynamics. Spark timing adjustment is used as a secondary degree of freedom to reduce combustion temperatures and limit NO x formation, with a slight efficiency penalty. The proposed torque-oriented control structure is compared with conventional gasoline and diesel control strategies and is evaluated using an engine simulation model, calibrated using experimental engine data. The proposed strategy largely reduces engine tip-in time response. Objective: Lean-burn turbocharged hydrogen engines suffer from slow torque response due to high air-flow requirements. Improving transient torque response while preserving combustion stability and limiting NOx emissions is essential for their practical deployment. • A real-time capable control strategy for transient torque response in hydrogen ICEs. • Adaptive air–fuel ratio management based on the current operating point. • Spark timing adjustment as a complementary degree of freedom to mitigate NO x emissions. • Dynamic bounds for safe operation, reducing conservative margins and preserving efficiency.