Co-Simulation of a BEV thermal management system in KULI and MATLAB Simulink with focus on model-based feedforward and feedback control of the HVAC system

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Abstract

In battery electric vehicles (BEV), the ongoing development of thermal management is of crucial importance to improve energy efficiency and lifetime of the vehicle. The optimal temperature ranges of battery and electric motor are at different levels, resulting in multiple fluid circuits, where methods for waste heat recovery contribute to increase efficiency. These aspects lead to thermal management systems with complex architectures and control strategies. Currently, automotive manufacturers use various cooling concepts with numerous architectures. The investigations at the Institute of Thermodynamics and Sustainable Propulsion Systems are intended to provide expertise regarding control and design of efficient thermal management systems for BEVs. These insights are expected to contribute to the development of superior system architectures for different vehicle requirements.

Due to the interactions between the various fluid circuits, optimization of control strategy and architecture requires an overall vehicle approach. Thus, a full vehicle simulation is set up, analyzing the Tesla Model 3 as a representative vehicle. This simulation allows an optimization of the control strategy of the thermal management system to reduce energy consumption for multiple operating points. The simulation is set up as a co-simulation in KULI and MATLAB Simulink. In KULI, the included libraries of vehicle components based on characteristic maps generally contribute to efficient thermo-hydraulic modeling, while MATLAB Simulink offers a high degree of freedom in mathematical-physical modeling.

The focus of the simulation set up at ITnA is less on modeling efficiency and more on generating in-depth knowledge about abstraction and modeling of thermal management at system and component level. Therefore, components like battery and electric motor are not based on the KULI library but are modeled thermally in MATLAB Simulink with a high level of detail. For instance, the battery is modeled starting from inner cell structure up to pack level in MATLAB. The interface to the coolant circuit in KULI is implemented by transferring the temperature at the contact surface between cooling channel and coolant from the MATLAB model to KULI, while transferring the heat flow between channel and coolant from the KULI model to MATLAB.

As the HVAC system represents a significant auxiliary consumer in BEVs, another focus is on the implementation of a realistic, fully automatic air-conditioning control system. The air path of the HVAC system in KULI represents the "real" air conditioning unit installed in the vehicle, with components such as evaporator and heaters being controlled via a MATLAB control strategy. For this, a feedforward control is implemented, where simultaneously to the "real" air path of the HVAC unit in KULI, mathematical-physical models of individual components are also calculated in MATLAB. These MATLAB models receive target values of the control strategy and sensor signals of the KULI components, from which a feedforward value is calculated and superposed with a feedback control value. This value is transferred to the KULI component as an actuating signal. That methodology is used for the control of heat outputs in evaporator and heaters and also for the position of temperature mixing flaps.

This co-simulation highlights the complexity of thermo-hydraulic modeling of thermal management systems. The scientific approach leads to complex modeling processes. Consequently, the option of using components from KULI library provides a much more efficient modeling, especially in industrial applications. Furthermore, the simulation illustrates the enormous range of functions offered by KULI in the context of co-simulation, and the capability to couple multiple simulation tools as a key strength of KULI.
Originalspracheenglisch
TitelECS Simulation Conference 2023
PublikationsstatusVeröffentlicht - 12 Mai 2023
VeranstaltungECS Simulation Conference 2023 - voestalpine Stahlwelt, Linz, Österreich
Dauer: 10 Mai 202311 Mai 2023
Konferenznummer: 2

Konferenz

KonferenzECS Simulation Conference 2023
Land/GebietÖsterreich
OrtLinz
Zeitraum10/05/2311/05/23

Schlagwörter

  • Vehicle Thermal Management System
  • Co-Simulation
  • Battery Electric Vehicles
  • HVAC Control
  • Modeling and Simulation

Fields of Expertise

  • Mobility & Production

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