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GreenZone Driving for Plug In Hybrid Electric Vehicles

2012-05-29
Plugin Hybrid Electric Vehicles (PHEV) have a large battery which can be used for electric only powertrain operation. The control system in a PHEV must decide how to spend the energy stored in the battery. In this paper, we will present a prototype implementation of a PHEV control system which saves energy for electric operation in pre-defined geographic areas, so called Green Zones. The approach determines where the driver will be going and then compares the route to a database of predefined Green Zones. The control system then reserves enough energy to be able to drive the Green Zone sections in electric only mode. Finally, the powertrain operation is modified once the vehicle enters the Green Zone to ensure engine operation is limited. Data will be presented from a prototype implementation in a Ford Escape PHEV Presenter Johannes Kristinsson
Technical Paper

Thermal Management for the HEV Liquid-Cooled Electric Machine

2001-05-14
2001-01-1713
The future of the Hybrid Electric Vehicle (HEV) is very promising for the automotive industry. In order to take a full advantage of this concept, a better thermal performance of the electric motor is required. In this study, Computational Fluid Dynamics (CFD) model was first verified through several prototypes testing and then is going to be used to execute a series of design of experiment via simulation. Based on the thermal studies in this paper, the integrated coolant jacket design has a better performance than that of separated one. The thermal performance of the stator with the 3M coating is better than the one with paper liner. In addition, using 3M coating reduces the packaging size of the stator.
Technical Paper

Control Strategies for a Series-Parallel Hybrid Electric Vehicle

2001-03-05
2001-01-1354
Living in the era of rising environmental sensibility and increasing gasoline prices, the development of a new environmentally friendly generation of vehicles becomes a necessity. Hybrid electric vehicles are one means of increasing propulsion system efficiency and decreasing pollutant emissions. In this paper, the series-parallel power-split configuration for Michigan Technological University's FutureTruck is analyzed. Mathematical equations that describe the hybrid power-split transmission are derived. The vehicle's differential equations of motion are developed and the system's need for a controller is shown. The engine's brake power and brake specific fuel consumption, as a function of its speed and throttle position, are experimentally determined. A control strategy is proposed to achieve fuel efficient engine operation. The developed control strategy has been implemented in a vehicle simulation and in the test vehicle.
Technical Paper

A Comparison of Different Methods for Battery and Supercapacitor Modeling

2003-06-23
2003-01-2290
In future vehicles (e.g. fuel cell vehicles, hybrid electric vehicles), the electrical system will have an important impact on the mechanical systems in the car (e.g. powertrain, steering). Furthermore, this coupling will become increasingly important over time. In order to develop effective designs and appropriate control systems for these systems, it is important that the plant models capture the detailed physical behavior in the system. This paper will describe models of two electrical components, a battery and a supercapacitor, which have been modeled in two ways: (i) modeling the plant and controller using block diagrams in Simulink and (ii) modeling the plant and controller in Dymola followed by compiling this model to an S-function for simulation in Simulink. Both the battery and supercapacitor model are based on impedance spectroscopy measurements and can be used for highly dynamic simulations.
Technical Paper

Simulation of Hybrid Electric Vehicles with Emphasis on Fuel Economy Estimation

1998-02-23
981132
This paper describes SHEV, a computer program created to simulate hybrid electric vehicles. SHEV employs the time-stepping technique in order to evaluate energy flow in series hybrids, and makes use of a unique method in order to speed up the fuel economy estimation. This estimation method is a refinement of the “state of charge matching” method and is explained in detail. The graphic user interfaces employed in SHEV make it easy to use and give it a look similar to regular Windows‚ applications. This paper also gives some examples of the screens created by the program, depicts its main flowchart, and describes a battery model optimized for this application.
Technical Paper

Cranktrain Design for Ford's HEV DI Diesel Engine

1998-08-11
981915
This paper focuses on the cranktrain design for Ford's HEV DI Diesel Engine called the DIATA. The design started with the piston pin. The minimum piston pin diameter for the lowest reciprocation weight was achieved by tapering the small end of the connecting rod. Geometry constraints sized the connecting rod's big end diameter, oil film analyses determined the width, and an FEA verified the design. Next, the crankshaft mains were sized to reach an acceptable factor of safety, bending and torsional stiffness, and oil films. Finally, the flywheel was sized to be the minimum weight to reduce transmission gear rattle to an acceptable level.
Technical Paper

Pole-Phase Modulation Motor Drives to Extend Torque-Speed Capability for xEV Applications

2017-03-28
2017-01-1235
Electric vehicles (EV) and hybrid electric vehicles (HEV) require high torque/acceleration ability and wide speed range. To meet both of them, the traction machines usually have to be oversized, which results in high volume and weight, high cost, and low efficiency. In practical application, high speed motors combining with gear box provide the expected torque and speed capability. If pole-changing machines are employed to achieve wide torque and speed ranges, gear box and motor size can be reduced in EVs/HEVs. This paper presents a pole-phase modulation motor drive which changes both of poles and phases simultaneously, as a result that the motor extends its torque/speed capability in a flexible way. Simulation results verify the principle and control method for this kind of motor drives.
Technical Paper

Nonlinear Model Predictive Control of a Power-Split Hybrid Electric Vehicle with Electrochemical Battery Model

2017-03-28
2017-01-1252
This paper studies the nonlinear model predictive control for a power-split Hybrid Electric Vehicle (HEV) power management system to improve the fuel economy. In this paper, a physics-based battery model is built and integrated with a base HEV model from Autonomie®, a powertrain and vehicle model architecture and development software from Argonne National Laboratory. The original equivalent circuit battery model from the software has been replaced by a single particle electrochemical lithium ion battery model. A predictive model that predicts the driver’s power request, the battery state of charge (SOC) and the engine fuel consumption is studied and used for the nonlinear model predictive controller (NMPC). A dedicated NMPC algorithm and its solver are developed and validated with the integrated HEV model. The performance of the NMPC algorithm is compared with that of a rule-based controller.
Technical Paper

Analytical Study on Electric Motor Whine Radiated from Hybrid Vehicle Transmission

2017-03-28
2017-01-1055
The automotive industry is experiencing a profound change due to increasing pressure from environmental and energy concerns. This leads many automakers to accelerate hybrid and electric vehicle development. Generally hybrid and electric vehicles create less noise due to their compact engines (or no engine). However, customer satisfaction could be negatively impacted by the peak whine emitted by electric motor. Unlike conventional gas vehicles, the strategy for reducing motor whine is still largely unexplored. This paper presents an analytical study on electric motor whine radiated from the transmission in a hybrid vehicle. The analysis includes two stages. Firstly, a detailed finite element (FE) model of the transmission is constructed, and case surface velocities are calculated utilizing motor electromagnetic force. Then a boundary element model is built for evaluating noise radiated from the transmission surface using acoustic transfer vector (ATV) method.
Technical Paper

Factors Influencing Liquid over Air Cooling of High Voltage Battery Packs in an Electrified Vehicle

2017-03-28
2017-01-1171
Automotive vehicle manufactures are implementing electrification technologies in many vehicle line-ups to improve fuel economy and meet emission standards. As a part of electrification, High Voltage (HV) battery packs are integrated alongside internal combustion engines. Recent generation HV batteries allow extensive power usage, by allowing greater charge and discharge currents and broader State of Charge (SOC) ranges. Heat generated during the charge-discharge cycles must be managed effectively to maintain battery cell performance and life. This situation requires a cooling system with higher efficiency than earlier generation electrified powertrains. There are multiple thermal solutions for cooling HV battery packs including forced air, liquid, direct refrigerant, and passive cooling. The most common types of HV battery pack cooling, for production vehicles, are air cooled using cabin interior air and liquid cooled using powertrain cooling systems.
Technical Paper

Estimation of the Effects of Auxiliary Electrical Loads on Hybrid Electric Vehicle Fuel Economy

2017-03-28
2017-01-1155
In recent years the fuel efficiency of modern hybrid electric vehicle (HEV) powertrains has progressed to a point where low voltage auxiliary electrical system loads have a pronounced impact on fuel economy (FE). While improving the energy consumption of an individual component may result in minor improvements, the collective optimization of such loads across a complete vehicle system can result in meaningful FE gains. Traditional methods using chassis dynamometer testing alone to quantify the impact of a specific auxiliary load can lead to issues where signal state changes are too small for accurate detection. This presents difficulties in accurately predicting the influence of such loads on FE of next-generation electrified vehicles under development. This paper describes a newly developed method where dynamometer test results are combined with computer simulation analyses to create a practical technique for assessing the impact of small changes in auxiliary load energy consumption.
Technical Paper

Regenerative Braking Control Development for P2 Parallel Hybrid Electric Vehicles

2017-03-28
2017-01-1149
Regenerative braking in hybrid electric vehicles is an essential feature to achieve the maximum fuel economy benefit of hybridization. During vehicle braking, the regenerative braking recuperates its kinetic energy, otherwise dissipated into heat due to friction brake, into electrical energy to charge the battery. The recuperation is realized by the driven wheels propelling, through the drivetrain, the electric motor as a generator to provide braking while generating electricity. “Rigid” connection between the driven wheels and the motor is critical to regenerative braking; otherwise the motor could drive the input of the transmission to a halt or even rotating in reverse direction, resulting in no hydraulic pressure for transmission controls due to the loss of transmission mechanical oil pump flow.
Technical Paper

Hybrid Powertrain Operation Optimization Considering Cross Attribute Performance Metrics

2017-03-28
2017-01-1145
Hybrid electric vehicles are continuously challenged to meet cross attribute performance while minimizing energy usage and component cost in a very competitive automotive market. As electrified vehicles become more mainstream in the marketplace, hybrid customers are expecting more attribute refinement in combination with the enhanced fuel economy benefits. Minimizing fuel consumption, which tends to drive hybrid powertrain engines to operate under lugging type calibrations, traditionally challenge noise, vibration, and harshness (NVH) metrics. Balancing the design space to satisfy the cost metrics, energy efficiency, noise and vibration & drivability under the hybrid engine lugging conditions can be optimized through the use of multiple CAE tools. This paper describes how achieving NVH metrics can put undesirable boundaries on Powertrain Operation which could affect other performance attributes.
Technical Paper

Real Time Application of Battery State of Charge and State of Health Estimation

2017-03-28
2017-01-1199
A high voltage battery is an essential part of hybrid electric vehicles (HEVs). It is imperative to precisely estimate the state of charge (SOC) and state of health (SOH) of battery in real time to maintain reliable vehicle operating conditions. This paper presents a method of estimating SOC and SOH through the incorporation of current integration, voltage translation, and Ah-throughput. SOC estimation utilizing current integration is inadequate due to the accumulation of errors over the period of usage. Thus voltage translation of SOC is applied to rectify current integration method which improves the accuracy of estimation. Voltage translation data is obtained by subjecting the battery to hybrid pulse power characterization (HPPC) test. The Battery State of Health was determined by semi-empirical model combined with accumulated Ah-throughput method. Battery state of charge was employed as an input to estimate damages accumulated to battery aging through a real-time model.
Technical Paper

Impact of Powertrain Type on Potential Life Cycle Greenhouse Gas Emission Reductions from a Real World Lightweight Glider

2017-03-28
2017-01-1274
This study investigates the life cycle greenhouse gas (GHG) emissions of a set of vehicles using two real-world gliders (vehicles without powertrains or batteries); a steel-intensive 2013 Ford Fusion glider and a multi material lightweight vehicle (MMLV) glider that utilizes significantly more aluminum and carbon fiber. These gliders are used to develop lightweight and conventional models of internal combustion engine vehicles (ICV), hybrid electric vehicles (HEV), and battery electric vehicles (BEV). Our results show that the MMLV glider can reduce life cycle GHG emissions despite its use of lightweight materials, which can be carbon intensive to produce, because the glider enables a decrease in fuel (production and use) cycle emissions. However, the fuel savings, and thus life cycle GHG emission reductions, differ substantially depending on powertrain type. Compared to ICVs, the high efficiency of HEVs decreases the potential fuel savings.
Technical Paper

Effect of State of Charge Constraints on Fuel Economy and Battery Aging when Using the Equivalent Consumption Minimization Strategy

2018-04-03
2018-01-1002
Battery State of Charge (SOC) constraints are used to prevent the battery in Hybrid Electric Vehicles (HEVs) from over-charging or over-discharging. These constraints strongly influence the power-split of the HEV. This paper presents results on how Battery State of Charge (SOC) constraints effects Lithium ion battery aging and fuel economy when using the Equivalent Consumption Minimization Strategy (ECMS). The vehicle studied is the Honda Civic Hybrid. The battery used is A123 Systems’ ANR26650 battery cell. Vehicle simulation uses multiple combinations of highway and city drive cycles. For each combination of drive cycles, nine SOC constraints ranges are used. Battery aging is evaluated using a semi-empirical model combined with the accumulated Ah-throughput method which uses, as an input, the battery SOC trajectory from the vehicle simulations. The simulation results provide insight into how SOC constraints effect fuel economy as well as battery aging.
Technical Paper

Modeling and Simulation of the Dual Drive Hybrid Electric Propulsion System

2009-04-20
2009-01-0147
The desire for improved vehicle fuel economy, driven by high gas prices and concerns over energy independence, have sparked interest and demand for hybrid electric vehicles. Hybrid electric vehicle propulsion systems exhibit complex interactions which need to be understood in order to maximize fuel economy over the range of operating modes. Model-based development processes which use vehicle system models capable of representing the functional behaviors with embedded controls are needed for fast, efficient design of vehicle control systems which manage overall energy usage. Model-based vehicle system development processes have been employed for a Dual Drive HEV system. The process for creating these vehicle system models is described along with an approach for using these models to develop HEV systems. Details of key subsystem models and the process for integration of full vehicle implementation level controls are discussed.
Technical Paper

Vehicle System Controls for a Series Hybrid Powertrain

2011-04-12
2011-01-0860
Ford Motor Company has investigated a series hybrid electric vehicle (SHEV) configuration to move further toward powertrain electrification. This paper first provides a brief overview of the Vehicle System Controls (VSC) architecture and its development process. The paper then presents the energy management strategies that select operating modes and desired powertrain operating points to improve fuel efficiency. The focus will be on the controls design and optimization in a Model-in-the-Loop environment and in the vehicle. Various methods to improve powertrain operation efficiency will also be presented, followed by simulation results and vehicle test data. Finally, opportunities for further improvements are summarized.
Technical Paper

A Statistical Approach to Assess the Impact of Road Events on PHEV Performance using Real World Data

2011-04-12
2011-01-0875
Plug in hybrid electric vehicles (PHEVs) have gained interest over last decade due to their increased fuel economy and ability to displace some petroleum fuel with electricity from power grid. Given the complexity of this vehicle powertrain, the energy management plays a key role in providing higher fuel economy. The energy management algorithm on PHEVs performs the same task as a hybrid vehicle energy management but it has more freedom in utilizing the battery energy due to the larger battery capacity and ability to be recharged from the power grid. The state of charge (SOC) profile of the battery during the entire driving trip determines the electric energy usage, thus determining overall fuel consumption.
Technical Paper

Energy Management in a Dual-Drive Hybrid Powertrain

2009-04-20
2009-01-1329
Ford Motor Company has developed a full hybrid electric vehicle with a dual-drive hybrid powertrain configuration that has great potential to overcome some attribute deficiencies in existing hybrid powertrain architectures. This paper first provides an overview of the dual-drive hybrid electric vehicle architecture and its primary operating modes. The paper then presents the energy management control system that selects operating modes and desired powertrain operating points to improve fuel efficiency. Finally, experimental results from a dual-drive hybrid prototype vehicle are used to demonstrate the fuel efficiency improvement.
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