Continental Engineering Services

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1 Automotive and transportation Services Product Simcenter Engineering firm uses Simcenter Amesim to optimize driving range of electric vehicles Business challenges Be recognized as an expert in electric vehicles Provide solutions to challenging technological assignments Support OEMs in reducing development time and costs Keys to success Evaluate the impact of thermal management strategies on vehicle performance Compare different battery heating and cooling methods Build on results to move forward on architecture definition Results Shortened early stages of design Optimized electric vehicle and increased driving range Enhanced reputation for expertise and knowledge in the marketplace Attaining energy efficiency One of the major concerns about battery systems used in electric vehicles is that their performance and durability can be diminished by extreme temperatures. In cold temperatures, the need for cabin and battery heating and the increased rolling resistance of winter tires are the most adverse conditions for any electric vehicle. The key is to determine how to allocate battery energy to make the most energyefficient use of the vehicle. On cold days, warming a battery gradually brings the system s temperature to a level that allows it to provide enough discharge power for expected vehicle performance. Like humans, a battery functions best at room temperature, and any deviations in temperature changes the battery performance and/or longevity. Battery heating systems and optimal thermal management are critical for effective operation in all climates. The objective is to deliver a battery pack at an optimum average temperature with even temperature distribution. The question is: how do you determine the best heating architecture? Leveraging expertise Since 2006, Services (CES) has been active worldwide as an independently operating provider of comprehensive engineering services. The extensive know-how and creativity of its engineers, as well as access to the entire Source: Continental.

2 I can state categorically that I am very enthusiastic about Simcenter Amesim. The intuitive operation and environment, the excellent support as well as the easy and stable model building that doesn t require advanced programming skills really help me in my daily work, and provide first results in record times. Department of System Integration and Vehicle Test Services, Nuremberg technology pool of international automotive suppliers puts the organization in the unique position of being able to combine the flexibility and speed of a small engineering team with the strength of a leading international company. In addition, the adaptability of CES enables the company to provide established mass production technology for small series as well as niche applications at economical costs. Based on years of experience and the constant exchange of knowledge within the Continental divisions, the CES Department of System Integration and Vehicle Test has achieved a great understanding of the entire hybrid and electric vehicle, including drive trains, transmissions and interior electronics. In the design phase, the layout of the high-voltage battery and the thermal and energy management strategies have to be specified. Despite space limitations, weight, complexity and cost limits, the requirements of driving range and performance have to be met. Finding the best possible solution takes numerous optimization loops, testing, experience and time, and that s where Simcenter Amesim software from Siemens PLM Software comes in. It enables engineers to optimize complex mechatronic systems in record time at reasonable cost. The expertise of CES has positioned the company to work on projects such as vehicle architecture and powertrain analysis of electric automobiles. That s why major original equipment manufacturers (OEMs) have turned to CES, especially for electrified drivetrain performance studies, optimization of heating systems and build-up of electrified prototype vehicles and demonstrators.

3 Determining the best approach The CES Department of System Integration and Vehicle Test started an investigation into cooling systems so it could understand the driving range implications. CES engineers had modeled the complete system of mission profile, virtual driver and vehicle, including the electric drivetrain containing electric motor and inverter with integrated DC/DC, LiOn battery (electrical data open-circuit voltage,resistance, cells, convective heat exchange to coolant) as well as the cooling circuit and the electric vehicle controller. The objective was to test three different battery-heating approaches in winter conditions to get the best performance in terms of range and power. State of charge [%] Cell temperature [ C] Velocity [km/h] Time [s] Time [s] Distance [km] Acceleration [m/s2] The first approach was the internal energy battery-heating scenario: as the internal resistance is high at low temperatures, it dissipates energy that will naturally heat the battery. The second approach uses the wasted heat from the drivetrain to heat the battery through more complex circuits. The third option relies on active electric heating in which additional circuits are designed that will use the energy of the battery for its own heating. Simulation conditions were the same for all three approaches: they started at minus 30 degrees Celsius (C) and ran two worldwide harmonized light vehicle test cycles (WLTC), and performed a simulation that showed very interesting results that were then confirmed by tests. The battery cells reached optimal temperature much faster with the third approach, active electric heating. It reached 0 degrees C in 14 minutes and 40 seconds and 6.5 kilometers driven, whereas it took about 28 minutes and 21 kilometers for the other two approaches to reach 0 degrees C and the same final state of By using Simcenter Amesim, we were able to model three approaches for the battery heating strategy and get the first results in a matter of hours instead of days. Department of System Integration and Vehicle Test Services, Nuremberg

4 charge of the battery (around 55 percent of capacity) at the end of the driving cycle. The active electric heating strategy was selected to be used to optimize the driving range and vehicle performance. By using Simcenter Amesim, we were able to model three approaches for the battery heating strategy and get the first results in a matter of hours instead of days, says, a system engineer in the Department of System Integration and Vehicle Test. We were able to rapidly select the right architecture with the best performance and focus on the next steps of the project. Accelerating the early design phase Before using Simcenter Amesim, every test was run mechanically on prototypes with the associated costs and delays to obtain results and make the necessary changes to reach the expected performance. By using Simcenter Amesim for multidomain mechatronic system simulation, the electric vehicle s performance and driving had been accurately predicted in an early phase of the development cycle. As a result, different battery sizes and configurations could be tested in the virtual vehicle environment. The influence of driving strategies and thermal management can be determined in a driving cycle, which allows the manufacturer to immediately choose the best architecture and components available for the application. With the use of Simcenter Amesim and its application-oriented libraries (cooling system, thermal hydraulics, mechanical, electric motors and drive), CES engineers were able to rapidly build a functional prototype and demonstrate results to management in order to validate selection of system architecture and components early in the design cycle.

5 Solutions/Services Simcenter Amesim simcenter-amesim Customer s primary business Services (CES) has been a worldwide provider of comprehensive engineering services since CES focuses on automotive electronics, drive and chassis technology and electrical mobility. The company is also experienced in adapting automobile technologies to a broad spectrum of industrial applications. Customer location Nuremberg Germany The unique Simcenter Amesim userfriendly interface the drag and drop approach of ready-to-use components, the intuitive operation and the easy parameter setup have helped CES engineers to rapidly select the best architecture and move forward in the component and subsystems selection to reach expected vehicle performance. I can state categorically that I am very enthusiastic about Simcenter Amesim, says Brixner. The intuitive operation and environment, the excellent support as well as the easy and stable model building that doesn t require advanced programming skills really help me in my daily work, and provide first results in record times. Simcenter Amesim really helps us by accelerating the early design phases of prototype development as well as optimizing the process of determining strategies and functions. We were able to rapidly select the right architecture with the best performance and focus on the next steps of the project. Department of System Integration and Vehicle Test Services, Nuremberg Siemens PLM Software Americas Europe +44 (0) Asia-Pacific Siemens Product Lifecycle Management Software Inc. Siemens and the Siemens logo are registered trademarks of Siemens AG. Femap, HEEDS, Simcenter 3D and Teamcenter are trademarks or registered trademarks of Siemens Product Lifecycle Management Software Inc. or its subsidiaries in the United States and in other countries. Simcenter, Simcenter Amesim, LMS Samtech Samcef, LMS Samcef Caesam, LMS SCADAS, LMS SCADAS XS, LMS Smart, LMS Test.Xpress, LMS Soundbrush, LMS Sound Camera, LMS Test.Lab and LMS Virtual.Lab are trademarks or registered trademarks of Siemens Industry Software NV or any of its affiliates. STAR-CCM+ and STAR-CD are trademarks or registered trademarks of Siemens Industry Software Computational Dynamics Ltd. All other trademarks, registered trademarks or service marks belong to their respective holders A13 12/17 H