Effects of Electrically Preheating Catalysts on Reducing High-Power Cold-Start Emissions

Plug-in hybrid electric vehicles (PHEVs) are typically built to provide a small, electric only driving range when fully charged. However, in parallel and series-parallel (blended) PHEVs the electric only driving power is usually limited to a fraction of the system power output. This means that during electric only operation there are some driving maneuvers that can force the internal combustion engine (ICE) to start in order to support the driver’s power request. The first time this happens after an extended vehicle soak, the engine and aftertreatment system are cold and the engine must go from an off-state to a high-speed and load-state as quickly as possible to support driver demand. This phenomenon is known as a high-power cold-start (HPCS). Thanks to the California Air Resources Board (CARB) and its published research regarding HPCS [1, 2], it is now known that HPCS poses a unique real-world emissions challenge that has not been fully covered by current test requirements or addressed by all current production PHEVs.

The Technology & Innovation team at Vitesco Technologies devised, implemented, and tested a unique potential solution to this real-world problem; the effectiveness of preheating a blended PHEV’s aftertreatment system was evaluated for reducing HPCS constituent emissions. This paper summarizes the process and methodology of building and testing such a system as well as an indication of the potential efficacy of such a system.