Battery Power - Summer 2016 - (Page 6)

Feature Toolbox Energy Storage Systems: Modeling, Simulating and Testing Battery Systems of (H)EVs Jörg Sauer, Senior Applications Engineer Modeling * dSPACE GmbH Friedrich Hust, Research Assistant * RWTH Aachen University Fabian Frie, Research Assistant * RWTH Aachen University The storage system used in electric vehicles (EVs) and hybrid electric vehicles (HEVs) is a key component of the drivetrain and defines the vehicle's performance. To tap the complete potential of storage systems, it must be possible to model, simulate and test them holistically and seamlessly. Developers of energy storage systems have to keep many different aspects and requirements in mind. Different thermal and electric factors have to be observed. The battery technology is just as important as the geometric shape, number and allocation of the storage cells. Developers also have to be aware of the temperature behavior, including the peripheral cooling system. In order to evaluate the overall system, engineers have to observe the thermal and electric effects at cell and system level and analyze the interplay of the individual cells with the peripheral cooling system, electrical system, housing and battery management. This is possible only if the system is embedded in the vehicle environment. The efficient development of storage systems and their design and integration in the vehicle, therefore, requires a seamless simulation-based environment that lets developers model, simulate and test the overall system. The models have to be real-time-capable so that the storage system can be integrated in the vehicle and tested together with the battery management system (BMS). The simulation-based Toolbox Energy Storage Systems environment supports the entire model-based development process of energy storage systems for electric powertrains. A detailed battery model was developed, which is used for system design and model-based BMS function development. If the real BMS is available, it can be tested on a hardware-in-the-loop (HIL) test bench that simulates the real-time-capable battery model. The model's parameterization defines the accuracy and level of detail of the battery model, enabling a seamless simulation and test environment. The work presented in this paper is the result of the Toolbox Energy Storage Systems project funded by the state of North Rhine-Westphalia and the EU. Storage System Model The Institute for Power Electronics and Electrical Drives (ISEA) of RWTH Aachen University developed a modeling framework for storage systems, which lets users simulate the electrical and thermal behavior of batteries in any sensible circuit (parallel or series). Batteries are strongly nonlinear systems that depend on the current operating point (especially on the state of charge, temperature, aging, and electrical load). Electrical The battery's electrical behavior can be approximated by an electrical equivalent circuit diagram whose elements change according to the operating point. To make the model as accurate as possible, special measurement tools and methods are used, such as electrochemical impedance spectroscopy (EIS) and relaxation measurement. ISEA has long-standing experience in battery parameterization and has already developed its own hardware solutions for various measurement methods. For example, the EISmeter, a laboratory measurement device for impedance spectroscopy in batteries, was developed at ISEA, brought to production quality by the Digatron company, and is now on the market. The batteries are analyzed in the on-site test center, where they are measured in special climate chambers under controlled and reproducible environment conditions. The measurement data is entered into look-up tables in the model. Figure 1 shows a typical workflow for the electrical parameterization of a 6 Battery Power * Summer 2016 www.BatteryPowerOnline.com http://www.BatteryPowerOnline.com

Table of Contents for the Digital Edition of Battery Power - Summer 2016

Toolbox Energy Storage Systems: Modeling, Simulating and Testing Battery Systems of (H)EVs
Enhancing Smartphone Battery Performance During GSM Pulses Through The Use of a Parallel Supercapacitor
Batteries
Components
ICs & Semiconductors
Charging Systems
Testing & Monitoring
Editor’s Choice
Research & Development
Conference Preview
Industry News
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Battery Power - Summer 2016