Optimal Catalytic Converter Heating in Hybrid Vehicles

Schori, Markus; Boehme, Thomas J.; Jeinsch, Torsten; Schultalbers, Matthias

doi:10.4271/2014-01-1351

Cited by 6 publications

(10 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Finally, they use a dynamic programming (DP) method to solve an optimal control problem, which could be implemented as an on-line controller. See also [5,6,10] for similar (scalar TWC temperature) approaches. Some authors chose to improve the accuracy of the TWC model by also modeling a TWC phenomenon wherein oxygen is absorbed and released from the TWC.…”

Section: Literature Surveymentioning

confidence: 99%

“…Note that (34) implies that the gas leaving each given cell is assumed to have the same temperature as the cell itself, i.e. each cell can be viewed as a reactor that is long enough for the moving gas to attain the same temperature as the cell before leaving (motivated by [6, p. 62] for N ≤ [2,5]). Also, recall that the final element ofTconvect stores the difference in temperature between the radially central and peripheral part, i.e.…”

Section: Convective Termsmentioning

confidence: 99%

“…Methods for reducing cold-start emissions have been studied extensively from several different perspectives, including TWC design methods that reduce the cold-start time [3], additional hardware that can pre-heat the TWC before starting the engine [4], and control schemes that control the engine's operation to reduce the generated emissions and/or heat the TWC more quickly [2,5,6,7,8]. One shared requirement for making a good design choice for all these tasks is a sufficiently accurate cold-start thermal model of the TWC.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Control-Oriented Spatially Resolved Thermal Model of the Three-Way-Catalyst

Lock

Clasén

Sjöblom

et al. 2021

SAE Technical Paper Series

View full text Add to dashboard Cite

The three-way-catalyst (TWC) is an essential part of the exhaust aftertreatment system in spark-ignited powertrains, converting nearly all toxic emissions to harmless gasses. The TWC's conversion efficiency is significantly temperature-dependent, and cold-starts can be the dominating source of emissions for vehicles with frequent start/stops (e.g. hybrid vehicles). In this paper we develop a thermal TWC model and calibrate it with experimental data. Due to the few number of state variables the model is well suited for fast offline simulation as well as subsequent on-line control, for instance using non-linear state-feedback or explicit MPC. Using the model could allow an on-line controller to more optimally adjust the engine ignition timing, the power in an electric catalyst pre-heater, and/or the power split ratio in a hybrid vehicle when the catalyst is not completely hot. The model uses a physics-based approach and resolves both axial and radial temperature gradients, allowing for the thermal transients seen during heat-up to be represented far more accurately than conventional scalar (i.e. lumped-temperature) real-time models. Furthermore, we also use a physics-based chemical kinetics reaction model for computing the exothermic heat of reaction and emission conversion rate which is temperature and residence-time-dependent. We have performed an experimental campaign with a standard spark-ignited engine and a commercial TWC, where we measured steady-state operation and cold-start transient behavior. This experimental data allowed us to tune the model, where we found excellent matching between the measured and modeled tailpipe emissions. Modeling the radial temperature gradient improved the relative accuracy of the conversion efficiency by 15%, and simulations indicate the potential for an absolute improvement by 15 percentage points for some cases. Furthermore, the modeled TWC temperature evolution for a cold-start was typically within ±10°C of the measured temperature (with a maximal deviation of 20°C). The proposed model thus bridges a gap between heuristic models suited for on-line control and accurate models for slower off-line simulation.

show abstract

Section: Literature Surveymentioning

confidence: 99%

Section: Convective Termsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Control-Oriented Spatially Resolved Thermal Model of the Three-Way-Catalyst

Lock

Clasén

Sjöblom

et al. 2021

SAE Technical Paper Series

View full text Add to dashboard Cite

show abstract

“…Several methods for reducing cold-start emissions have been studied from a multiple perspectives. These range from methods of constructing the TWC that reduces the cold-start time [27], methods for preheating the TWC before starting the combustion engine [11], and control schemes that focus on controlling the combustion engine's operation to limit the emissions generated during the cold-start [10,12,15,23,29].…”

Section: Introductionmentioning

confidence: 99%

Cold-Start Modeling and On-Line Optimal Control of the Three-Way Catalyst

Lock

Clasén

Sjöblom

et al. 2021

Emiss. Control Sci. Technol.

View full text Add to dashboard Cite

We present a three-way catalyst (TWC) cold-start model, calibrate the model based on experimental data from multiple operating points, and use the model to generate a Pareto-optimalcold-start controller suitable for implementation in standard engine control unit hardware. The TWC model is an extension of a previously presented physics-based model that predicts carbon monoxide, hydrocarbon, and nitrogen oxides tailpipe emissions. The model axially and radially resolves the temperatures in the monolith using very few state variables, thus allowing for use with control-policy based optimal control methods. In this paper, we extend the model to allow for variable axial discretization lengths, include the heat of reaction from hydrogen gas generated from the combustion engine, and reformulate the model parameters to be expressed in conventional units. We experimentally measured the temperature and emission evolution for cold-starts with ten different engine load points, which was subsequently used to tune the model parameters (e.g. chemical reaction rates, specific heats, and thermal resistances). The simulated cumulative tailpipe emission modeling error was found to be typically − 20% to + 80% of the measured emissions. We have constructed and simulated the performance of a Pareto-optimal controller using this model that balances fuel efficiency and the cumulative emissions of each individual species. A benchmark of the optimal controller with a conventional cold-start strategy shows the potential for reducing the cold-start emissions.

show abstract

“…In order to meet increasingly stringent emissions regulations from governments, exhaust aftertreatment systems are necessary even for inherently low‐emission hybrid electric vehicles (HEVs). The aftertreatment systems in gasoline–electric hybrids, namely three‐way catalytic (TWC) converters, has been studied and its conversion efficiency can be simply modeled as a function of the catalyst temperature . A dynamic programming (DP)‐based supervisory control algorithm has been proposed to optimize both fuel consumption and tailpipe emissions during cold start in .…”

Section: Introductionmentioning

confidence: 99%

Comparative Study and Accommodation of Biodiesel in Diesel‐Electric Hybrid Vehicles Coupled with Aftertreatment Systems

Zhao

Chen

Ibrahim

et al. 2015

Asian Journal of Control

View full text Add to dashboard Cite

Biodiesel is a promising renewable alternative fuel, which can be used in diesel‐electric hybrid vehicles to potentially bring one kind of clean vehicle on the road. However, the fuel property variation can cause impacts to the powertrain and aftertreatment systems. In this paper, biodiesel's influence on post‐injection effects is studied. Experimental results are obtained to demonstrate the differences between diesel and biodiesel, and to build up fuel‐dependent maps of engine torque, temperature, and emissions. Utilizing those maps, an aftertreatment warm‐up approach compatible with both fuels is developed by strategically enabling double post injections. Finally, a supervisory controller based on model predictive control method is designed to optimize and balance the tradeoff between hybrid vehicle fuel economy and tailpipe emissions. Simulations are conducted for both fuels with or without the proposed control strategy. The validation results show that for both fuels, the controller can significantly reduce tailpipe emissions by successfully regulating the catalyst temperature to the desired range sacrificing fuel economy. And for biodiesel, additional fuel cost is required in order to realize the tradeoff.

show abstract

Optimal Catalytic Converter Heating in Hybrid Vehicles

Cited by 6 publications

References 15 publications

A Control-Oriented Spatially Resolved Thermal Model of the Three-Way-Catalyst

A Control-Oriented Spatially Resolved Thermal Model of the Three-Way-Catalyst

Cold-Start Modeling and On-Line Optimal Control of the Three-Way Catalyst

Comparative Study and Accommodation of Biodiesel in Diesel‐Electric Hybrid Vehicles Coupled with Aftertreatment Systems

Contact Info

Product

Resources

About