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A Theoretical and Experimental Analysis of the Coulomb Counting Method and Estimation of the Electrified-Vehicles Electricity Balance Over the WLTP

European Commission Joint Research-Alessandro Tansini, Georgios Fontaras
Politecnico di Torino-Federico Millo
  • Technical Paper
  • 2020-37-0020
To be published on 2020-06-23 by SAE International in United States
The energy storage devices of electrified vehicles (Hybrid Electric Vehicles and Battery Electric Vehicles) are required to operate with highly dynamic current and power outputs, both for charging and discharging operation. When calculating the vehicle CO2 emissions and electrical energy consumption from a trip, the change in electrical energy content at vehicle-level has to be accounted for. This quantity, referred to as the electricity balance in the WLTP regulation, is normally obtained through a time-integration of the current or power supplied by the vehicle batteries during operation and the efficiency factor is often assumed to be unitary (as in the official type-approval procedure). The Joint Research Centre has collected experimental data from different electrified vehicles with regards to electrical energy use and battery State Of Charge (SOC) profile; the latter was used as a reference to quantify the actual vehicle electricity balance from a trip or driving cycle. In this work, the approach of using a simple Coulomb counting method with unitary efficiency for charging and discharging for the quantification of the vehicle electricity balance…
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Fuel consumption on different drive cycles: A unified approach based on average power/weight

Ford Motor Company-Patrick Phlips, William Ruona, Thomas Megli, Mrudula Orpe
  • Technical Paper
  • 2020-01-1278
To be published on 2020-04-14 by SAE International in United States
In previous work we have shown that fuel consumption on a particular drive cycle is proportional to traction work, with an offset for powertrain losses. The finding applies to different drive cycles, but with different offsets. Following Soltic (2011), it is shown that if fuel usage and traction work are both expressed in terms of cycle average power, a wide range of drive cycles collapse to a single transfer function. Data for vehicles of different weights further collapses when normalized for weight, i.e. by working in power/weight (P/W). The fuel P/W is primarily a function of traction P/W, and secondarily of displacement/weight. The useful work or power definition is then expanded beyond the traction power to include electrical power for customer functions, and power to drive the air conditioning. With this expanded definition the linear powertrain transfer function can be applied not only to strictly defined regulatory drive cycles and procedures, but also to ‘real driving’ conditions that cover a much broader range of situations. When applied to hybrid electric vehicles, the method clearly shows…
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Minimization of Electric Heating of the Traction Induction Machine Rotor

South Ural State University-Elena Nikiforova, Victor Smolin
University of Michigan-Sergey Gladyshev
  • Technical Paper
  • 2020-01-0562
To be published on 2020-04-14 by SAE International in United States
The article solves the problem of reducing electric power losses of the traction induction machine rotor to prevent its overheating in nominal and high-load modes. Electric losses of the rotor power are optimized by the stabilization of the main magnetic flow of the electric machine at a nominal level with the amplitude-frequency control in a wide range of speeds and increased loads. The quasi-independent excitation of the induction machine allows us to increase the rigidity of mechanical characteristics, decrease the rotor slip at nominal loads and overloads and significantly decrease electrical losses in the rotor as compared to other control methods. The article considers the technology of converting the power of individual phases into a single energy flow using a three-phase electric machine equivalent circuit and obtaining an energy model in the form of equations of instantaneous active and reactive power balance. The quasi-independent excitation of the induction machine is performed according to the model by stabilizing the current of the magnetizing branch using the algorithms to control the voltage amplitude, synchronous frequency and electromagnetic…
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An Evaluation of Future Topologies and Architectures for Highly Reliable Electrical Distribution Systems

University of Kassel-Ludwig Brabetz, Mohamed Ayeb, Janis Lehmann, Benjamin Löwer
  • Technical Paper
  • 2020-01-1296
To be published on 2020-04-14 by SAE International in United States
Within the scope of the development of autonomous vehicles, the continuous introduction of automated driving functions considerably increases the mandatory reliability requirements of the electrical power supply, and consequently of the electrical distribution system (EDS). In addition, the overall rising number of electrical functions in future vehicles leads to significantly higher electrical power demands, while strict cost, weight and packaging constraints must be upheld. Current developments focus mostly on the improvement of the conventional EDS, e.g. by adding redundancies, enhancing physical robustness, or redimensioning critical components. New approaches address predictive power management, better diagnostic capabilities, and, the subject of this paper, new topologies and architectures. Alternative topologies are derivations of the conventional tree structure, as well as ring- or linear-bus-based zonal architectures, which feature in part distributed storage devices or semiconductor switches that rearrange the power paths in case of a fault. The presented approach is a method for both the systematical description of EDS topologies and architectures, and the assessment of their reliability. It is based on a data model designed for a simple…
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A Novel Supervisory Control and Analysis Approach for Hybrid Electric Vehicles

BorgWarner Inc.-Nithin Kondipati, Xiaobing Liu, Sara Mohon, Dmitriy Semenov, John Shutty
  • Technical Paper
  • 2020-01-1192
To be published on 2020-04-14 by SAE International in United States
There are many methods developed over the past decade to solve the problem of energy management control for hybrid electric vehicles. A novel method is introduced in this paper to address the same problem which reduces the problem to a set of physical equations and maps. In simple terms, this method directly calculates the actual cost or savings in fuel energy from the generation or usage of electric energy. It also calculates the local optimum electric power that yields higher electric fuel savings (EFS) or lower electric fuel cost (EFC) in the fuel energy that is spent for driving the vehicle (which in general does not take the system to the lowest engine Brake Specific Fuel Consumption (BSFC)). Based on this approach, a control algorithm is developed which attempts to approach the global optimum over a drive cycle. The main objective of this paper is to introduce the theoretical background and mathematical formulation of EFX (EFS/EFC) metric and explain the development of EFX maps for a specific architecture. Later, these maps are used to develop…
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Understanding Charging Flexibility of Shared Autonomous Electric Vehicle Fleets

National Renewable Energy Laboratory-Matthew Moniot, Yanbo Ge, Nicholas Reinicke, Alex Schroeder
  • Technical Paper
  • 2020-01-0941
To be published on 2020-04-14 by SAE International in United States
The combined anticipated trends of vehicle sharing, autonomous control, and powertrain electrification are poised to disrupt the current paradigm of predominately gasoline vehicles with low levels of utilization. Shared, autonomous, electric vehicle (SAEV) fleets, which encompass all three of these trends, have garnered significant interest among the research community due to the opportunity for low-cost mobility with congestion and emissions reductions. This paper explores the charging loads demanded by SAEV fleets in response to servicing personal light-duty vehicle travel demand in four major United States metropolitan areas: Detroit, Austin, Washington DC, and Miami. A coordinated charging model is introduced which minimizes fleet charging costs and corresponding plant emissions in response to different renewable energy penetration rates and shares of personal trip demand served (between 1% and 25%). The relationship between trip demand by time of day, electricity price by time of day, and SAEV fleet size versus overall charging flexibility is explored for each city. SAEV results are presented across various scenarios assuming fleetwide attempts to minimize charging costs while still constrained by offering adequate…
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A Modular Gasoline Engine Family for Hybrid Powertrains: Balancing Cost and Efficiency Optimization

AVL LIST GmbH-Wolfgang Schoeffmann, Michael Howlett, Alois Fuerhapter, Paul Kapus, Christoph Sams, Helfried Sorger
  • Technical Paper
  • 2020-01-0839
To be published on 2020-04-14 by SAE International in United States
The electrification of the powertrain is a prerequisite to meet future fuel consumption limits, while the internal combustion engine (ICE) will remain a key element of most production volume relevant powertrain concepts. High volume applications will be covered by electrified powertrains. The range will include parallel hybrids, 48V- or High voltage Mild- or Full hybrids, up to Serial hybrids. In the first configurations the ICE is the main propulsion, requiring the whole engine speed and load range including the transient operation. At serial hybrid applications the vehicle is generally electrically driven, the ICE provides power to drive the generator, either exclusively or supporting a battery charging concept. As the ICE is not mechanically coupled to the drive train, a reduction of the operating range and thus a partial simplification of the ICE is achievable. The paper shows the advances on a modular powertrain technology approach with different combinations of ICE, electrification and transmission variants, based on an engine family architecture with common parts, machining and assembly concepts, as well as the feasibility to integrate different…
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Effect of Oil Viscosity and Driving Mode on Oil Dilution and Transient Emissions Including Particle Number in Plug-In Hybrid Electric Vehicle

Shell (Shanghai) Technology Limited-Weizi Li, Tian Jia, Bin Zheng
Shell Global Solutions (UK)-Robert Taylor
  • Technical Paper
  • 2020-01-0362
To be published on 2020-04-14 by SAE International in United States
Plug-in electric vehicle (PHEV) has a promising prospect to reduce greenhouse gas (GHG) emission and optimize engine operating in high-efficiency region. According to the maximum electric power and all-electric range, PHEVs are divided into two categories, including “all-electric PHEV” and “blended PHEV” and the latter provides a potential for more rational energy distribution because engine participates in vehicle driving during aggressive acceleration not just by motor. However, the frequent use of engine may result in severe emissions especially in low state of charge (SOC) and ahead of catalyst light-off. This study quantitatively investigates the impact of oil viscosity and driving mode (hybrid/conventional) on oil dilution and emissions including particle number (PN). Two cycles, WLTC (World-wide Harmonized Light Duty Driving Test Cycle) and continuous ECE 15 (European Driving Cycle), were adopted and initial SOC was controlled in the range of 10-13%, which can induce more engine start events. Oil dilution is detected through method of ASTM D3525-04 to identify dilution rate under different conditions. Results show that both in WLTC and ECE 15, frequent engine start…
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Development of RC-IGBT with a New Structure That Contributes to Both Reduced Size of Power Control Unit and Low Loss in Hybrid Electric Vehicles

Toyota Central R&D Labs, Inc.-Hiroko Iguchi, Sachiko Kawaji
Toyota Motor Corporation-Koichi Murakami, Tasbir Rahman, Keisuke Kimura, Masaki Konishi
  • Technical Paper
  • 2020-01-0596
To be published on 2020-04-14 by SAE International in United States
In order to improve the fuel efficiency of Hybrid Electric Vehicles (HEVs), it is necessary to reduce the size and power loss of the HEV Power Control Units (PCUs). The loss of power devices (IGBTs and FWDs) used in a PCU accounts for approximately 20% of electric power loss of an HEV. Therefore, it is important to reduce the power loss while size reduction of the power devices. In order to achieve the newly developed PCU target for compact-size vehicles, the development targets for the power device were to achieve low power loss equivalent to its previous generation while size reduction by 25%. The size reduction was achieved by developing a new RC-IGBT (Reverse Conducting IGBT) with an IGBT and a FWD integration. As for the power loss aggravation, which was a major issue due to this integration, we optimized some important parameters like the IGBT and FWD surface layout and backside FWD pattern. As a result, it was possible to avoid the snapback characteristic (IGBT loss aggravation). In addition the substrate thickness was reduced…
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Optimal Management of Charge and Discharge of Electric Vehicles Based on CAN Bus Communication

Suizhou-WUT Industry Research Institute-Gangfeng Tan
Wuhan University of Technology-Haoyu Wang, Donghua Guo, Zhenyu Wang, Hanyu Zhang, Zhicheng Hu
  • Technical Paper
  • 2020-01-1297
To be published on 2020-04-14 by SAE International in United States
With the shortage of energy and the continuous development of automotive technology, electric vehicles are gradually gaining popularity. However, during the running of the electric vehicle, there is a risk of exhaustion of the electric power, and the position of the charging pile is fixed, which is likely to cause anxiety and worry of the owner. At present, there is a lack of an effective energy consumption prediction system, which is convenient for the driver to make reasonable driving planning guidance. As a standard serial communication protocol of ISO, CAN bus has a simple structure, short development cycle, stability and reliability. In this paper, the CAN bus is used to extract the dynamic parameter information of the speed, engine speed and throttle opening of the traveling vehicle in real time. At the same time, based on the GPS and cloud database, the road condition information of the expected driving section is comprehensively considered, and the real-time energy consumption prediction model of the electric vehicle is established. The predicted value is compared with the remaining electricity,…