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SAE International Journal of Alternative Powertrains
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A Linear Parameter Varying Combined with Divide-and-Conquer Approach to Thermal System Modeling of Battery Modules

SAE International Journal of Alternative Powertrains

ANSYS Inc.-Saeed Asgari
General Motors Co-Shailendra Kaushik
  • Journal Article
  • 2015-01-9148
Published 2016-05-01 by SAE International in United States
A linear parameter varying (LPV) reduced order model (ROM) is used to approximate the volume-averaged temperature of battery cells in one of the modules of the battery pack with varying mass flow rate of cooling fluid using uniform heat source as inputs. The ROM runs orders of magnitude faster than the original CFD model. To reduce the time it takes to generate training data, used in building LPV ROM, a divide-and-conquer approach is introduced. This is done by dividing the battery module into a series of mid-cell and end-cell units. A mid-cell unit is composed of a cooling channel sandwiched in between two half -cells. A half-cell has half as much heat capacity as a full-cell. An end-cell unit is composed of a cooling channel sandwiched in between full-cell and a half-cell. A mass flow rate distribution look-up-table is generated from a set of steady-state simulations obtained by running the full CFD model at different inlet manifold mass flow rate samples. This look-up-table is used to build a series of mid-cell and end-cell LPV ROMs…
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An Experimental Survey of Li-Ion Battery Charging Methods

SAE International Journal of Alternative Powertrains

Fiat Chrysler Automobiles-Rami Abousleiman
Oakland University-Abdullah AL-Refai, Osamah Rawashdeh
  • Journal Article
  • 2015-01-9145
Published 2016-05-01 by SAE International in United States
Lithium-Ion batteries are the standard portable power solution to many consumers and industrial applications. These batteries are commonly used in laptop computers, heavy duty devices, unmanned vehicles, electric and hybrid vehicles, cell phones, and many other applications. Charging these batteries is a delicate process because it depends on numerous factors such as temperature, cell capacity, and, most importantly, the power and energy limits of the battery cells. Charging capacity, charging time and battery pack temperature variations are highly dependent on the charging method used. These three factors can be of special importance in applications with strict charging time requirements or with limited thermal management capabilities. In this paper, three common charging methods are experimentally studied and analyzed. Constant-current constant-voltage, the time pulsed charging method, and the multistage constant current charging methods were considered. Charge capacity, charge time and temperature variations vary based on the selected charging method. These variations are compared and contrasted. The presented results help engineers to better choose a more suitable charging method based on the design requirements and the system constraints…
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Prediction of Lithium-ion Battery's Remaining Useful Life Based on Relevance Vector Machine

SAE International Journal of Alternative Powertrains

Wuhan University of Technology-Zhiyun Zhang, Miaohua Huang, Yupu Chen, Shuanglong Zhu
  • Journal Article
  • 2015-01-9147
Published 2016-05-01 by SAE International in United States
In the field of Electric Vehicle (EV), what the driver is most concerned with is that whether the value of the battery's capacity is less than the failure threshold because of the degradation. And the failure threshold means instability of the battery, which is of great danger for drives and passengers. So the capacity is an important indicator to monitor the state of health (SOH) of the battery. In laboratory environment, standard performance tests can be carried out to collect a number of related data, which are available for regression prediction in practical application, such as the on-board battery pack.Firstly, we make use of the NASA battery data set to form the observed data sequence for regression prediction. And a practical method is proposed to determine the minimum embedding dimension and get the recurrence formula, with which a capacity model is built. Afterwards, an optimized Relevance Vector Machine (RVM) algorithm is utilized to improve the prediction performance as well as the operating efficiency and get a tradeoff between training time and computational complexity. Finally, given…
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Vibration Torque Interception using Multi-Functional Electromagnetic Coupling in a HEV Drive Line

SAE International Journal of Alternative Powertrains

Toyota Central R&D Labs Inc-Takao Watanabe
Toyota Motor Corporation-Tadashi Fujiyoshi, Akira Murakami
  • Journal Article
  • 2016-01-1181
Published 2016-04-05 by SAE International in United States
In the present paper, we introduce a drivetrain system using an electromagnetic coupling for hybrid electric vehicles, and propose a new control concept of vibration torque interception. The electromagnetic coupling is an electric machine that is composed of a pair of rotors, and electromagnetic torque acts mutually between the rotors. In the drivetrain system, the electromagnetic coupling works as a torque transmission device with a rotational-speed-converting function. We demonstrate that, by using this control, the electromagnetic coupling also works as a damping device that intercepts the vibration torque of the internal combustion engine, while transmitting the smooth torque to its drive line. Using a model of a two-inertia resonance system, a control system is designed such that a transfer function representing input-to-output torque is shaped in the frequency domain. Experimental results obtained using an electromagnetic coupling demonstrate the effectiveness of the proposed concept.
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CO2 Emissions Reduction via 48V Active Engine-Off Coasting

SAE International Journal of Alternative Powertrains

HELLA Electronics Corp-Alan Brown
HELLA KGaA Hueck & Co.-Marc Nalbach, André Korner
  • Journal Article
  • 2016-01-1152
Published 2016-04-05 by SAE International in United States
Global CO2 reduction by 2021, according to some projections, will be comprised of multiple vehicle technologies with 7% represented by hybrid and electric vehicles (2% in 2014) [1]. Other low cost hybrid methods are necessary in order to achieve widespread CO2 reduction. One such method is engine-off coasting and regenerative braking (or recuperation) using a conventional internal combustion engine (ICE).This paper will show that a 48V power system, compared to a 12V system with energy storage module for vehicle segments B, D and E during WLTP and NEDC, is much more efficient at reducing CO2. Passive engine-off coasting using 12V energy storage shows a CO2 benefit for practical real world driving, but, during NEDC, multiple sources of friction slow the vehicle down to the extent that the maximum benefit is not achieved. By adding active engine-off coasting at the 48V level the CO2 emissions for NEDC are improved by decreasing the rate of deceleration with a 48V electric motor for propulsion. Also important, which will be explored in more detail, are the necessary power dimensions…
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Employing Hot Wire Anemometry to Directly Measure the Water Balance of a Commercial Proton Exchange Membrane Fuel Cell Stack

SAE International Journal of Alternative Powertrains

Aalborg University-Saher Al Shakhshir, Torsten Berning
  • Journal Article
  • 2016-01-1191
Published 2016-04-05 by SAE International in United States
Proton exchange membrane fuel cells (PEMFC’s) are currently being commercialized for various applications ranging from automotive (e.g. the Toyota Mirai) to stationary such as powering telecom backup units. In PEMFC’s, oxygen from air is internally combined with hydrogen to form water and produce electricity and waste heat. One critical technical problem of these fuel cells is still the water management: the proton exchange membrane in the center of these fuel cells has to be hydrated in order to stay proton-conductive while on the other hand excessive liquid water can lead to cell flooding and increased degradation rates. Clearly, a fundamental understanding of all aspects of water management in PEMFC is imperative. This includes the fuel cell water balance, i.e. which fraction of the product water leaves the fuel cell via the anode channels versus the cathode channel. Our research group is currently developing a novel technique to obtain an ad-hoc and real time electrical signal of the fuel cell water balance by employing hot wire anemometry. In this work, the hot wire sensor is placed…
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A Load Spectrum Data based Data Mining System for Identifying Different Types of Vehicle Usage of a Hybrid Electric Vehicle Fleet

SAE International Journal of Alternative Powertrains

Daimler AG-Christof Nitsche
Esslingen University of Applied Sciences-Philipp Bergmeir, Jürgen Nonnast
  • Journal Article
  • 2016-01-0278
Published 2016-04-05 by SAE International in United States
In order to achieve high customer satisfaction and to avoid high warranty costs caused by component failures of the power-train of hybrid electric vehicles (HEV), car manufacturers have to optimize the dimensioning of these elements. Hence, it is obligatory for them to gain knowledge about the different types of vehicle usage being predominant all over the world. Therefore, in this paper we present a Data Mining system that employs a Random Forest (RF) based dissimilarity measure in the dimensionality reduction technique t-Distributed Stochastic Neighbor Embedding (t-SNE) to automatically identify and visualize different types of vehicle usage by applying these methods to aggregated logged on-board data, i.e., load spectrum data. This kind of data is calculated and recorded directly on the control units of the vehicles and consists of aggregated numerical data, like the histogram of the velocity signal or the traveled distance of a vehicle. We empirically demonstrate the performance of the proposed Data Mining system by carrying out a real-world case study using load spectrum data of a HEV fleet, containing the logged on-board…
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Improvement of Ride Comfort by Unsprung Negative Skyhook Damper Control Using In-Wheel Motors

SAE International Journal of Alternative Powertrains

Toyota Motor Corporation-Etsuo Katsuyama, Ayana Omae
  • Journal Article
  • 2016-01-1678
Published 2016-04-05 by SAE International in United States
Vehicles equipped with in-wheel motors (IWMs) are capable of independent control of the driving force at each wheel. These vehicles can also control the motion of the sprung mass by driving force distribution using the suspension reaction force generated by IWM drive. However, one disadvantage of IWMs is an increase in unsprung mass. This has the effect of increasing vibrations in the 4 to 8 Hz range, which is reported to be uncomfortable to vehicle occupants, thereby reducing ride comfort. This research aimed to improve ride comfort through driving force control. Skyhook damper control is a typical ride comfort control method. Although this control is generally capable of reducing vibration around the resonance frequency of the sprung mass, it also has the trade-off effect of worsening vibration in the targeted mid-frequency 4 to 8 Hz range. This research aimed to improve mid-frequency vibration by identifying the cause of this adverse effect through the equations of motion. As a result, a method was derived by analysis that reduced vibration over a wide mid-frequency range by a…
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A Method for the Exploration of Hybrid Electric Powertrain Architectures with Two Planetary Gearsets

SAE International Journal of Alternative Powertrains

University of Michigan - Ann Arbor-Oguz H. Dagci, Huei Peng
  • Journal Article
  • 2016-01-1164
Published 2016-04-05 by SAE International in United States
The goal of this paper is to explore the complete set of single mode hybrid electric powertrain designs that can be generated with one and two planetary gearsets (PGs). Contrary to an automated design exploration approach, an analytically-based manual method is developed to identify all unique design modes for each hybrid electric powertrain architecture (parallel, series, power-split) that can be created with two planetary gearsets, one engine, one vehicle output shaft, two electric machines, and at most two brake clutches. Feasible design modes are generated according to a procedure that provably covers the entire design space. The procedure systematically creates all feasible combinations according to the number of connections between PGs; the number of brake clutches; whether brake clutches, vehicle output shaft, and engine are connected to the nodes that combine two PGs; whether engine and vehicle output shaft are connected to the same PG; whether they are connected to the PG with brake clutches and whether electric machines are collocated with the engine and/or vehicle output shaft. The results of this approach not only…
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A New Approach to Calorimetric Efficiency Measurements and Analysis of Electric Vehicle Drive Losses

SAE International Journal of Alternative Powertrains

University of Kassel-Dennis Kuhl, Ludwig Brabetz, Mohamed Ayeb
  • Journal Article
  • 2016-01-1168
Published 2016-04-05 by SAE International in United States
The development of battery electric vehicle drives comes along with comprehensive and time-consuming finite element methods and extensive measurement campaigns. The drive efficiency has drawn great attention from engineers and customers, because it influences the size of the drive, the cooling measures and the vehicle range.Indirect efficiency acquisition accomplished by comparing inward and outward power, has a low accuracy which arises from a relatively small difference between inward and outward power of highly efficient drives. Therefore the indirect efficiency acquisition is insufficient to evaluate advanced development measures. This paper presents measurement and analysis methods developed within a collaborative research project, which aims at accelerating the development cycles of electrical drives by implementing and combining accuracy-improved Finite Element Simulations (FEM), extremely rapid Lumped Parameter Thermal Networks (LPTN) and a new efficiency measurement method with high accuracy. Findings of this project provide possibilities to optimize drive construction, material selection and control strategy.The new approach of efficiency measurements is based on a direct loss measurement. Moreover, this approach adopts an innovative calorimetric measurement principle with the support of…
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