Robust MIMO air handling control for eboosted off-road hybrid diesel powertrain

This paper describes the development and experimental validation of robust single input single output (SISO) & multiple input multiple output (MIMO) H ∞ controllers for a turbocharged diesel engine equipped with an electrified intake boosting system. The intake boosting system is activated during transient operations to mitigate drops in the air-to-fuel ratio (AFR), enabling improved speed and power control without unacceptable transient smoke or NOx emissions. Initially, a two-degree-of-freedom robust H ∞ SISO eBooster controller was synthesized to control the eBooster during load transients. Although the robust SISO controller yields improvements compared to when the engine was run without e-boosting, the lack of coordination with the modulations of the other actuators (exhaust throttle and EGR valve) results in inferior engine response relative to what is demonstrated when the control algorithm does not ignore the coupling effects of the actuations on the engine gas exchange process. To address this, a robust model-based MIMO controller is developed using a physics-based mean value engine model, calibrated against high-fidelity engine simulation software. Both SISO and MIMO controllers are implemented and validated through simulation and experimental testing on an engine dynamometer. The MIMO controller outperforms the SISO controller, showing superior AFR, DAR (Diluent Air Ratio), and engine speed recovery during load transients. When the MIMO controller operates with the electrified intake boosting system, the engine recovers to a steady state 70% faster than the baseline, and reduces engine speed droop by 45%. This improves the engine’s ability to accept load torque significantly. Using a single robust MIMO controller proves more effective than employing multiple PIDs or look-up tables for each actuator.