Real Time Implementation of DOC-DPF Models on a Production-Intent ECU for Controls and Diagnostics of a PM Emission Control System 2009-01-2904

This paper describes the joint development by Tenneco and Pi Shurlok of a complete diesel engine aftertreatment system for controlling particulate matter emissions. The system consists of a DOC, DPF, sensors, controller and an exhaust fuel injection system to allow active DPF regeneration.

The mechanical components were designed for flow uniformity, low backpressure and component durability. The overall package is intended as a complete PM control system solution for OEMs, which does not require any significant additions to the OEM's engine control strategies and minimizes integration complexity. Thus, to make it easier to adapt to different engine platforms, ranging from small off-road vehicle engines to large locomotive engines, model-based control algorithms were developed in preference to map-based controls.

Pi's recently-developed general-purpose OpenECU electronic controller, based on the MPC-5534 processor core, was applied to run the advanced 1-D DOC and 0-D lumped DPF thermo-chemical models in real time to control the fuel injection system. The system was integrated with a Cummins 5.9 L engine in the engine dynamometer laboratory at Tenneco. The control algorithm and models were first calibrated offline using the experimental and baseline engine data using Hardware-ln-the-Loop test environment. The control strategies were then tested in real time on the engine dynamometer. The models were able to predict DOC and DPF parameters such as temperatures, pressure drop, soot load and emissions in real time with good accuracy. These “virtual sensor” measurements provide great scope for advanced diagnostic strategies to detect component or sensor failures. During active regeneration, the control strategy was able to control the DOC outlet temperature within a range of +/-50 °C from the set target and effectively regenerate the DPF under engine transients. The HC slip measured was less than 60 PPM during active regeneration.

These system performance results confirmed the feasibility of active DPF regeneration in the context of increasingly stringent regulations for emissions limits and increasingly complex diagnostic requirements.