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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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New Integrated Electromagnetic and NVH Analyses of Induction Traction Motors for Hybrid and Electric Vehicle Applications

General Motors LLC-Song He, Jingchuan Li, Michael Muir, Gautam GSJ, Bhyri Rajeswara Rao
  • Technical Paper
  • 2020-01-0413
To be published on 2020-04-14 by SAE International in United States
Electric motor whine is one of the main noise sources of hybrid and electric vehicles. Compared with permanent magnetic motors, characterization and prediction of traction induction motor is particularly challenging due to high computational costs to calculate the electro-magnetic (EM) forces as noise source, as well as motor slip and harmonic orders change at different torque/speed operating conditions. Historically, induction motor NVH is designed qualitatively by optimizing motor topology including rotor bar, pole number and slot counts etc. A new integrated electromagnetic and NVH analysis method is developed and successfully validated at all dominant motor orders for an automotive traction motor, which enables quantitative prediction of induction motor N&V performance in early design stage: First, a new Equivalent Rotor Current Method (ERCM) is proposed that significantly reduces the computational time required to calculate the EM force over transient response. Dominant force orders are compared with conventional EM finite-element (FE) results and the new ERCM method shows good correlation. Next, a High-Fidelity (Hi-Fi) mechanical FE model is developed for the induction motor stator, with less than…
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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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Android Defense in Depth Strategy in an Automobile Ecosystem

Automotive Accessories-Nalinikanth Yerram
Embedded Systems Software & Security-Srinivas Chandupatla
  • Technical Paper
  • 2020-01-1365
To be published on 2020-04-14 by SAE International in United States
Android is becoming an environment of choice in the automotive sector for the ease of use, large open source community and Play store applications. With growing interest from Automotive OEM's in Android for IVI (In Vehicle Infotainment) solutions we predict similar trend like in Mobile World. As the need for more interconnected devices within the Automobile ecosystem increasing, IVI plays a critical role in interfacing user actions which can directly impact security of the ecosystem. In sophisticated device interconnections, Identifying the key gateways and implementing the right security strategy is key to improve performance and overall system security & stability. Defining clear defense in depth strategy in complex interconnected environment plays a critical role in ensuring overall system security. While Android is maturing for automotive and with growing traction in automotive, we spent time in analyzing current android defense in depth concepts with automobile perspective. Main aim of this paper is to examine current defense of depth strategies and propose additional measures to meet automotive needs starting from information security to functional safety. This paper…
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Comparative Study on the Effects of the Tread Rubber Compounds on Tire Tractive performance on Ice

Virginia Tech-Hoda Mousavi, Corina Sandu
  • Technical Paper
  • 2020-01-1228
To be published on 2020-04-14 by SAE International in United States
Mechanical and thermal properties of the rubber compounds of a tire play an important role in the overall performance of the tire when it is in contact with the train. Although there are many studies conducted on the properties of the rubber compounds of the tire to improve some of the tire characteristics such as the wear of the tread, there is a limited number of studies that focus on the performance of the tires on ice. This study is part of a more comprehensive study to investigate the effect of rubber compounds on performance of the tire on ice. In this study three tires that are completely identical in terms of tire parameters (such as tire dimensions, treat pattern, tire structure, inflation pressure, etc., but have different tread rubber compounds have been investigated. Several tests have been conducted for the chosen tires in three modes: free rolling, braking, and traction using the Terramechanics Rig at TMVS at Virginia Tech. In this presentation we will only focus on the result for the traction tests. The…
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Analytical model to predict the fatigue life of tubular welded structures subjected to compressive loading

American Axle & Manufacturing, Inc.-Anoop Vasu, Shizhu Xing, Jifa Mei, William Webster, Scott Jacob, Jerry Chung, Ravi Desai
  • Technical Paper
  • 2020-01-0185
To be published on 2020-04-14 by SAE International in United States
It has been well documented that welded components can fail under pure compression under fatigue loading conditions (R=-∞). Unlike non-welded components, the mean stress effect has shown to have little impact (Gurney, 1979). Currently, most weld prediction procedures does not involve mean stress effect and the relationship involves stress range (or strain range) plotted against the number of cycles to failure. Two case studies were performed to understand the mean stress effect of tubular welds. First case was weld under compressive pre-stress (caused by bolt pretension) subjected to tension and compressive loading. Second case was weld under no pre-stress subjected to the same tension and compressive loading. It was observed that the welds under compression for tubular structures (eg; an axle tube) demonstrated significant resistance to fatigue failure. Traction structural stress method has proven to be very effective for the fatigue life prediction of welded structures. However, the predictions for the two case studies considered in this research were under-predicting the fatigue life significantly. This paper propose an analytical model to capture the weld behavior…
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Optimizing Gear Ratio Selection for Lap Performance

Univ. of Alabama-Robert Frederick
University of Alabama-Brandon Dixon
  • Technical Paper
  • 2020-01-0543
To be published on 2020-04-14 by SAE International in United States
The goal of this paper is to select the optimal gear ratios to determine the best overall lap time for a racing vehicle. Given a discrete set of individual gear ratio and final drive ratio options, the simulation chooses the set of gears and final drive that produce the minimum overall lap time. For example, one vehicle studied in this paper, an F2000 formula car, has 32 ratio choices for four forward gears and a final drive that has three different options. The simulation will iterate through the gear options to find the optimal gear selection for the best lap performance, accounting for various factors that could cause improper selection of gears. The simulation accounts for aerodynamic factors, gear shift time, rolling resistance and tire scrub. All values have been estimated from logged vehicle data, but experimental data can be easily used to help improve the vehicle model. Two vehicles were used in this simulation to compare the different types of racing and how that affects the gear selection. The first vehicle is the F2000…
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Development and Demonstration of a New Range-Extension Hybrid Powertrain Concept

Tongji University-Zhiyu Han, Zhenkuo Wu, Xiaojie Gao, Yongzheng Sun, Runyu Ni, Jian Feng, Jian zhong, Xinbo Chen, Zhiguo Zhao, Zhuoping Yu
  • Technical Paper
  • 2020-01-0845
To be published on 2020-04-14 by SAE International in United States
A new range-extension hybrid powertrain concept, namely the Tongji Extended-range Hybrid Technology (TJEHT) was developed and demonstrated in this study. This hybrid system is composed of a direct-injection gasoline engine, a traction motor, an integrated starter-generator (ISG) motor, and a transmission. In addition, an electronically controlled clutch between the ISG motor and engine, and an electronically controlled synchronizer between the ISG motor and transmission are also employed in the transmission case. Hence, this system can provide six basic operating modes including the single-motor driving, dual-motor driving, serial driving, parallel driving, engine-only driving and regeneration mode depending on the engagement status of the clutch and synchronizer. Importantly, the unique dual-motor operation mode can improve vehicle acceleration performance and the overall operating efficiency. The hybrid system controls and energy management strategy based on equivalent fuel consumption minimization were developed and validated. The choice of an operating mode is optimized according to the drivers’ demand, actual vehicle state, operation conditions, and other boundary conditions. In this paper, the powertrain architecture and operating modes are firstly described. Secondly, the…
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Lumped Parameter Thermal Network Modeling for Online Temperature Prediction of Permanent Magnet Synchronous Motor for Different Drive Cycles in Electric Vehicle Applications

University of Windsor-Muhammad Towhidi, Firoz Ahmed, Shruthi Mukundan, Ze Li, Narayan C. Kar
  • Technical Paper
  • 2020-01-0455
To be published on 2020-04-14 by SAE International in United States
Electric vehicle is increasingly becoming popular and an alternate choice in automotive industries because of its environment-friendly operation. Permanent magnet synchronous machines are widely and commonly used as traction motors since they provide higher torque and power density. High torque and power density means higher current which eventually causes higher temperature rise in the motor. Higher temperature rise directly affects the motor output. Standard tests for UDDS (Urban Dynamometer Driving Schedule) and HWEFT (Highway Fuel Economy Driving Schedule) drive cycles are used to determine performance of traction motors in terms of torque, power, efficiency and thermal health. Traction motors require high torque at low speed for starting and climbing; high power at high speed for cruising; wide speed range; a fast torque response; high efficiency over wide torque and speed ranges and high reliability. For both UDDS and HWEFT driving conditions, it is essential to monitor the performance of the motor and predict the temperature of stator winding and magnet in order to maintain required torque and power generation. This paper proposes a simplified Lumped…
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Longitudinal Vehicle Dynamics Modeling for AWD/4WD Vehicles to study torque split between front and rear axles.

FCA US LLC-Prashant Sondkar, Swapneel Gharpure, Vince Schrand, Pradeep Attibele
  • Technical Paper
  • 2020-01-1410
To be published on 2020-04-14 by SAE International in United States
All-wheel Drive (AWD) is a mature technology and most automobile manufacturers offer this feature on their vehicles. Improved traction, enhanced vehicle stability, and better handling are some of the key characteristics of AWD vehicles which are achieved by distributing appropriate level of torque to the front and rear axles. Accurately capturing the torque split between the two axles is essential for sizing of driveline components like gears, bearings, and shafts. Traditionally, the torque split is considered to be either 50-50%, or solely proportional to the static weight distribution between the two axles. Design decisions are made based on historical test data. In this paper longitudinal vehicle dynamics model for AWD systems is proposed to understand the influence of various key factors such as dynamic weight transfer, compliance of driveline components, changing tire radius, and tire pressure on the torque split. Comparison with the test data is performed to understand the significance and limitations of the model. While more detailed models have been built and used for various purposes, to the authors' knowledge, this is the…