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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

Motion Analysis Enhances Visualization of Underbody Flow

2001-03-05
2001-01-0628
Velocity profiles for air flowing under a vehicle body are determined by analyzing videotapes of neutrally buoyant soap bubbles using motion analysis software and equipment. What had heretofore been primarily a qualitative flow visualization technique has been extended to provide quantitative data. The light sources, cameras, and bubble generator, mounted on the vehicle, are powered by the vehicle's electrical system, making it possible to compare underbody velocities measured in a wind tunnel with those over the road. Results are presented for a heavy-duty 4×4 pickup truck at speeds up to 25m/s (55 mph). The velocity profiles in the tunnel and on the road were quite similar.
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

Drawbeads in Sheet Metal Stamping - A Review

1997-02-24
970986
The paper reviews the role of drawbeads in sheet metal stamping. The design of drawbeads is discussed in depth, with treatment of different bead cross sections, bead end shapes, and bead materials. International standards and practices are included. This is followed by the historical development of the modeling of the drawbead restraining force, starting with basic equilibrium approaches, and leading to the use of the finite element method which permits the study of drawbead effects on sheet metal flow in three dimensions. Finally, the potential of active drawbeads is described based upon ongoing research which is directed toward closed-loop computer control of the stamping process through adjustment of the drawbead penetration.
Technical Paper

Effect of the Variable Switching Frequency and DPWM Switching Schemes on the Losses of Traction Drives

2017-03-28
2017-01-1227
This paper studies different switching schemes for loss reduction in a traction motor drive. The system under examination is composed of a battery, a 2 level Voltage Source Inverter, and an Interior Permanent Magnet motor. Discontinuous PWM (DPWM) control strategy is widely used in this type of motor drive for the reduction of losses. In some publications, the effect of the DPWM modulation scheme is compared to the reduction of the switching frequency which can also cause a reduction in switching losses of the inverter. Extensive studies have examined the effect of variation of the switching frequency on the motor and inverter losses. However, the effect of applying both switching schemes simultaneously has not been explored. This paper will use a system that is operated at a fixed switching frequency as the baseline. Afterwards, three different switching schemes will be studied and compared to the baseline.
Technical Paper

Life Balancing – A Better Way to Balance Large Batteries

2017-03-28
2017-01-1210
A new cell balancing technology was developed under a Department of Energy contract which merges the DC/DC converter function into cell balancing. Instead of conventional passive cell balancing technology which bypasses current through a resistor, or active cell balancing which moves current from one cell to another, with significant cost and additional inefficiencies, this concept takes variable amount of current from each cell or small group of cells and converts it to current for the low voltage system.
Technical Paper

Deconstruction of UN38.3 into a Process Flowchart

2017-03-28
2017-01-1208
This paper will discuss a compliance demonstration methodology for UN38.3, an international regulation which includes a series of tests that, when successfully met, ensure that lithium metal and lithium ion batteries can be safely transported. Many battery safety regulations, such as FMVSS and ECE, include post-crash criteria that are clearly defined. UN38.3 is unique in that the severity of the tests drove changes to battery design and function. Another unique aspect of UN38.3 is that the regulatory language can lead to different interpretations on how to run the tests and apply pass/fail criteria; there is enough ambiguity that the tests could be run very differently yet all meet the actual wording of the regulation. A process was created detailing exactly how to run the tests to improve consistency among test engineers. As part of this exercise, several tools were created which assist in generating a test plan that complies with the UN38.3 regulation.
Technical Paper

Traction Inverter Design with a Direct Bypass to Boost Converter

2017-03-28
2017-01-1247
Direct bypass to DC-DC boost converter in traction inverter increases converter's capability and efficiency significantly by providing a lower loss path for power flow between the battery and DC-link terminal. A bypass using diode is an excellent solution to achieve this capability at low cost and system complexity. Bypass diode operates in the linear operating region (DC Q-point) when the battery discharges through the bypass diode to drive the electric motors. Therefore, thermal stress on the DC-link capacitor is shared between the input and DC-link capacitors through the bypass diode. On the other hand, inverters introduce voltage oscillation in the DC-link terminal which results in unwanted energy oscillation through the bypass diode during battery charging. Both of these phenomena have been explained in details.
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

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

Fast Charging Lithium-Ion Batteries

2017-03-28
2017-01-1204
We try to understand the fast recharge capability of automotive lithium-ion batteries and its effect of fast charge on capacity degradation. We find out that 5 Ah prismatic Li-ion cells can be fully recharged in 3 minutes under a constant rate of 20C, or in 2 min (25.5C) from 0% to 85% state of charge (SOC) without undue stresses. We cycle the battery at 16C charge rate from 0 to 100%SOC and do not see any unexpected battery capacity loss in 50 cycles, where half of the cycles are charged at1C-rate as a reference capacity check. We realize that the batteries under the fast charge tests do not experience any negative impacts related to mass transport in either solid electrodes or the electrolyte system. In the paper, we propose a new procedure to measure the ac and dc resistances of the battery under continuous operation. Electrochemical impedance analyses on the whole battery and the individual electrodes are also conducted.
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 Manual Service Disconnect in an Automotive Traction Battery System (RESS)

2017-03-28
2017-01-1195
SAE standards require the function of a Manual Service Disconnect (MSD), when open, to remove any voltage between positive and negative Rechargeable Energy Storage System (RESS) output terminals. Another SAE standard specifies that measured voltage across all external battery terminal sets shall be less than 60 VDC within 5 seconds after the manual disconnect is actuated with the automatic disconnect (e.g., contactors) closed. In this paper, the location of the manual service disconnect is reviewed to meet isolation requirement of the battery pack system (i.e., RESS). Battery architectures with manual service disconnect located at the most positive side, most negative side, and center of the array or the pack were studied. Voltage measurement points and single point failure modes were considered. It was found that MSD location for a single contactor pack is most effective in reducing voltage potential at the terminals when placed on the other side of the contactor.
Technical Paper

Manage and Optimize Power System to Maximize Steering Assist and Stop-Start Availability

2017-03-28
2017-01-1176
Auto stop-start (Engine stop-start, ESS) has become a widely used feature to reduce fuel consumption and CO2 emissions particularly in congested cities. Typically, vehicles equipped with such systems include two DC power sources that are coupled in parallel: a primary and a secondary power source. The primary power source supplies energy to the starter to crank the engine, while the secondary power source supplies energy to the rest of the vehicle electric loads. During an auto-stop event, a controllable switch decouples the two power sources. Moreover, operating current, voltage and the State of Charge (SOC) are monitored to ensure enough energy for the next auto-start event. When any of these operating parameters are below the threshold values, the controllable switch opens to isolate the two batteries and then the engine is automatically started.
Technical Paper

Robust Observer Roll Rate Sensor Fault Detection

2017-03-28
2017-01-1572
The detection and diagnosis of sensor faults in real-time is necessary for satisfactory performance of vehicle Electronic Stability Control (ESC) and Roll Stability Control (RSC) systems. This paper presents an observer designed to detect faults of a roll rate sensor that is robust to model uncertainties and disturbances. A reference vehicle roll angle estimate, independent of roll-rate sensor measurement, is formed from available ESC inertial sensor measurements. Residuals are generated by comparing the reference roll angle and roll rate, with the observer outputs. Stopping rules based on the current state of the vehicle and the magnitude of the residuals are then used to determine if a sensor fault is present. The system’s low order allows for efficient implementation in real-time on a fixed-point microprocessor. Modification of the roll rate sensor signal during in vehicle experiments shows the algorithm’s ability to detect faults.
Technical Paper

Model-Based Analysis of V2G Impact on Battery Degradation

2017-03-28
2017-01-1699
Vehicle-to-Grid (V2G) service has a potential to improve the reliability and stability of the electrical grid due to the ability of providing bi-directional power flow from/to the grid. However, frequent charging/discharging may impact the battery lifetime. This paper presents the analysis of battery degradation in three scenarios. In the first scenario, different battery capacities are considered. In the second scenario, the battery degradation with various depth of discharge (DOD) are studied. In the third scenario, the capacity loss due to different charging regime are compared. The charging/discharging of plug-in electric vehicles (PEVs) are simulated in a single-phase microgrid system integrated with a photovoltaics (PV) farm, an energy storage system (ESS), and ten electric vehicle service equipment (EVSE). The battery degradation model is an energy throughput model, which is developed based on the Arrhenius equation and a power law relationship between time and capacity fading.
Technical Paper

Development of a Thermal Model for a Heated Steering Wheel to Compensate Defective Feedback Variables

2017-03-28
2017-01-1636
Along with the development and marketability of vehicles without an internal combustion engine, electrically heated surfaces within these vehicles are getting more and more important. They tend to have a quicker response while using less energy than a conventional electric heater fan, providing a comfortable temperature feel within the cabin. Due to the big area of heated surface it is important to spread the heating power in a way that different heat conduction effects to underlying materials are considered. In case an accurate sensor feedback of the targeted homogeneous surface temperature cannot be guaranteed, a thermal energy model of the heated system can help to set and maintain a comfortable surface temperature. For a heated steering wheel development project, different models have been created to meet that aim using mechanistic approaches starting with a predominantly first-order dynamics model and ending with a distributed parameter multi-feedback system.
Technical Paper

Full Scale Burn Test of Four Aluminum Body Ford F-150’s

2017-03-28
2017-01-1355
Four full scale burn tests on aluminum body Ford F-150’s were conducted with four unique origins. The purpose of these burn tests was to determine if the origin of the fire could be accurately identified after the vehicle fires progressed to near complete burn (with near absence of the aluminum body panels). The points of origin for the four burn tests were: 1) Engine Compartment - driver’s side front of engine compartment, 2) Passenger Compartment - Instrument panel, driver’s side near the headlamp switch, 3) Passenger Compartment - passenger side rear seat, 4) Outside of Vehicle - passenger side front tire. Photographic, video, and temperature data was recorded to document the burn process from initiation to extinguishment. Post-fire analysis was conducted in an attempt to determine the origin of the fire based solely on the burn damage.
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.
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