High-Temperature High-Power Packaging Techniques for HEV Traction Applications

Plug-in hybrid electric vehicle (PHEV) presents the new trend of clean energy vehicle development due to their advantage of all electric driving, allowable external charging, lower emissions, and lower petroleum fuel consumption, comparing to the maturing HEV. Applications of advanced plug-in hybrid powertrain system technology to different type of vehicles lead to the need to identify the key characteristics of these different vehicular applications, and to develop more systematic and effective powertrain design methods. In this work two different types of PHEV powertrain architecture were investigated: a) pre- trans series-parallel multi-regime plug-in hybrid electric commercial vehicle (SPMR-PHEV), and b) post-trans parallel plug-in hybrid electric formula racing car. Model-based design (MBD) methods were used for powertrain system modelling of the two PHEV applications. With the powertrain system models developed using MATLAB Simulink and dSPACE Automotive Simulation Models (ASM), the powertrain configurations, control strategies and key features were investigated. The simulation results on standard driving cycles for each model using different rule-based control strategies were compared. The differences and key features of two types of vehicle in design and calibration were presented and analyzed.

EPRI and DaimlerChrysler developed a Plug-in Hybrid Electric Vehicle (PHEV) using the Sprinter Van to reduce emissions, fuel consumption, and operating costs while maintaining equivalent or superior functionality and performance. The utilization of grid electricity and operating efficiency significantly reduce petroleum consumption, greenhouse gas emissions, and criteria pollutants, especially benefiting urban areas.Southern California Edison (SCE) collaborated with EPRI and DaimlerChrysler to evaluate the vehicle and two different battery technologies. This paper documents one of the first published battery test results related to PHEV applications from the beginning of the project, in September 2004.The partners selected two advanced battery technologies, lithium ion (Li-Ion) chemistry from SAFT and nickel metal hydride (NiMH) chemistry from VARTA. The primary goals of the test are to evaluate the performance and cycle life of traction batteries for future PHEV Sprinter Van production using PHEV test profiles. The test profile replicates the most demanding urban driving conditions for the battery (i.e., low speed, high acceleration in charge-sustained HEV mode at low battery state of charge). It also uses a combination of HEV and EV driving modes to represent over 50% of statistical daily trips. One cycle includes three modes: (1) charge depletion mode, simulating the EV operation, (2) charge sustained mode, simulating the HEV operation, and (3) recharge mode, simulating the plug-in operation.The SAFT battery technology shows encouraging results from simulated PHEV tests; one test cycle represents an average daily operation of a PHEV Sprinter Van (i.e., a 2.6-hour, 50-mile drive).

This paper presents a new approach to life estimation for lithium-ion batteries used in plug-in hybrid electric vehicles (PHEVs) applications. A new framework for battery life estimation is developed which investigates the effects of two primary factors of battery life reduction in PHEVs applications, namely, depth of discharge (DOD) and temperature (Tbatt), under typical driving conditions, driving habits, and average commute time of typical user over a year. This framework, whose development is built upon a weighted ampere-hour throughput model of the battery, is based on the novel concept of severity factor map which captures and quantifies the battery damage caused by different operating conditions. The proposed methodology can be a suitable tool to estimate battery life in terms of miles/year on-board of the vehicle.

Plug-in hybrid electric vehicles (PHEVs) are specialized hybrid electric vehicles that have the potential to obtain enough energy for average daily commuting from batteries. These batteries would be charged from the power grid and would thus allow for a reduction in the overall petroleum consumption. To implement the plug-in function, a single phase bidirectional AC-DC converter interfacing with the grid is essential. The implementation of a bidirectional AC-DC converter can allow for battery recharge from the grid, battery energy injection to the AC grid, and battery energy for AC power stabilization. In this paper, the basic requirements and specifications for PHEV bidirectional AC-DC converter designs are presented. Generally, there are two types of topologies used for PHEVs: an independent topology and a combination topology that utilizes the drive motorpsilas inverter. Evaluations of the two converter topologies are analyzed in detail. The combination topology analysis is emphasized because it has more advantages in PHEVs, in respect to savings in cost, volume and weight.

Plug-in hybrid electric vehicles (PHEVs) are being considered as an alternative to conventional medium-duty (MD) and heavy-duty (HD) commercial vehicles to reduce fuel consumption and tailpipe emissions. Lithium ion batteries, which are used in PHEVs due to their high energy density, are expensive. The battery contributes significantly towards the life-cycle cost of MD/HD PHEVs, as these vehicles, due to high mass and aggressive battery usage, require multiple battery replacements over their lifetime. Smaller batteries increase the fuel consumption and need more replacements, while bigger batteries increase the initial system cost. Powertrain design from a life-cycle cost perspective is required to explore this trade-off and maximize the economic gains obtained from PHEVs. Powertrain design entails component sizing, control strategy selection as well as architecture selection. Different powertrain designs yield different lifetime economic gains. A variety of applications exist for MD/HD vehicles, which differ in their ways of powertrain usage, due to variations in required acceleration, available braking, and average and maximum speeds. Therefore, different powertrain designs are needed depending on the application and usage scenario. The powertrain design space needs to be explored, and solutions that maximize the economic gains within the specified constraints need to be chosen.This dissertation compares the economic viability of two PHEV applications (MD Truck and HD Transit Bus), with options of series and parallel hybrid architectures, over multiple drivecycles, for four economic scenarios (years 2015, 2020, 2025 and 2030). It is shown that hybridizing the transit bus achieves payback sooner than hybridizing the truck. Further, the results for the transit bus application, over the Manhattan drivecycle, show that implementation of the parallel architecture is economically viable in the 2015(present) scenario, while the series architecture becomes viable in 2020, due to significantly lower initial costs involved in the parallel architecture.A methodology to select a solution out of the explored design space that maximizes the economic gains is demonstrated. Variations in the economic and vehicle usage conditions for which this solution is designed, can be expected. It is therefore necessary to check the robustness of this solution to change in external factors such as vehicle mass, annual vehicle miles travelled (AVMT), component and fuel costs. It is shown that the economic gains are affected by the battery cost, fuel cost, AVMT and vehicle mass, while the number of battery replacements are affected by AVMT and vehicle mass. A probability-based approach is demonstrated to obtain confidence in the economic and battery life predictions. Specifically, probability-based variations are provided to variables such as miles traveled between recharge, recharge C-rate and battery temperature. It is shown that battery life is affected the most by battery temperature.A battery heating/cooling system is required to maintain constant battery temperature of operation during all seasons, but these systems incur additional fuel costs. A framework that utilizes just the Coefficient of Performance (COP) of the heating/cooling system to calculate the excess fuel cost is proposed and demonstrated. An increase of 0.9-1.8\% in fuel consumption is shown, depending on the drivecycle and ambient temperature.Further, the well-to-wheel (WTW) fuel-cycle emissions from conventional and PHEV transit buses operating in Indiana and California are assessed using the ``Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation'' (GREET) Model 2017, developed by Argonne National Labs. It is shown that 59% and 63% greenhouse gas (GHG) reductions can be achieved in Indiana and California respectively, along with reduction in carbon monoxide (CO), nitrogen oxides NOx, particulate matter with diameter less than 2.5 microns PM2.5 and volatile organic compounds (VOC) emissions for both the states. However, an increase in sulfur oxides SOx emissions for both the states, and particulate matter with diameter less than 10 microns PM10 increase for Indiana, are observed.

This paper comparatively examines three different electrochemical energy storage systems (ESSs), i.e., a Li-ion battery pack, a supercapacitor pack, and a dual buffer, for a hybrid bus powertrain operated in Gothenburg, Sweden. Existing studies focus on comparing these ESSs, in terms of either general attributes (e.g., energy density and power density) or their implications to the fuel economy of hybrid vehicles with a heuristic/nonoptimal ESS size and power management strategy. This paper adds four original contributions to the related literature. First, the three ESSs are compared in a framework of simultaneous optimal ESS sizing and energy management, where the ESSs can serve the powertrain in the most cost-effective manner. Second, convex optimization is used to implement the framework, which allows the hybrid powertrain designers/integrators to rapidly and optimally perform integrated ESS selection, sizing, and power management. Third, both hybrid electric vehicle (HEV) and plug-in HEV (PHEV) scenarios for the powertrain are considered, in order to systematically examine how different the ESS requirements are for HEV and PHEV applications. Finally, a sensitivity analysis is carried out to evaluate how price variations of the onboard energy carriers affect the results and conclusions.

Plug-in hybrid electric vehicles (PHEVs) connect two energy systems—the electric power network and the transportation sector—in ways that could provide significant public health benefits. To begin, it is important to...

The government policies and cost benefits led to the surge in penetration of Plug-in Hybrid Electric Vehicles (PHEVs) and Battery Electric Vehicles (BEVs) into both public and private sectors, challenging the electric grid's potential to maintain its stability and efficiently serve the purpose. The penetration of PHEVs brings technological advancements and environmental benefits to the traditional transportation and electrical power systems. Designing of appropriate charging methods to satisfy PHEV owners helps to improve system performance and avoid transmission and distribution system expansion.;The primary objective of this thesis is to model a coordinated charging algorithm to charge maximum number of PHEVs with the existing infrastructure at a Charging Station (CS) located in residential locality. The stochastic driving patterns of PHEVs are studied and different charging strategies are developed. The Optimized charging scheme is obtained for American Electric Power utility distribution feeder modeled in OpenDSS. Further, PHEV customers are modeled into price responsive consumers capable of participating in Demand Response programs to economically charge their vehicles and render support to the stabilization of power system. Consumer behavior modeling has been done by developing extensive demand-price elasticity matrices (PEMs) which are utilized to calculate the level of demand response.;This thesis also proposes a concept of converting the existing Personal Rapid Transit (PRT) system from guideway power rail propelling vehicles to Battery Electric Vehicles (BEVs) by developing a novel routing algorithm based on the data provided by West Virginia University's Department of Transportation and Parking. This turns into a feasibility analysis of implementing new EV technologies in electrification of public transportation. The routing algorithm involves Mixed Integer Linear Programming (MILP) Optimization resulting in hourly schedule of all the vehicles satisfying the passenger demand. The effect of charging load of BEVs on the electrical distribution system is analyzed by performing a time series simulation on AEP distribution feeder.;Additionally, the impact of PHEV charging on power market prices i.e. Locational Marginal Prices (LMP) in a distribution microgid scenario is presented. Locational marginal pricing is a market based wholesale pricing approach adopted by six out of ten national electricity markets. The uncoordinated charging of EVs results in unplanned peak demand causing system changes and fluctuation of LMP. The stabilizing effect of coordinated charging scheme is demonstrated on IEEE 13 Node test system.

This paper presents a comprehensive life-cycle analysis of CO2(LCCO2) emissions from automobiles using a hybrid life-cycle inventory approach to predict the growth of electrified vehicles in Japan. Herein, the hybrid electric vehicle (HEV), plug-in HEV (PHEV), and battery electric vehicle (BEV) versions of the mass-produced Toyota Prius hatchback are analyzed, considering the automobile-usage environment in Japan. In particular, a breakeven analysis of HEV vs. PHEV vs. BEV is conducted in terms of LCCO2emissions that are affected by (i) outside air temperature and (ii) CO2emissions during power generation from the present day up to 2030. Our results show that HEV has the lowest LCCO2emissions when the current thermal-power-dependent electricity generation mix (average for 2012–2014) is considered, followed in order by PHEV and BEV. However, it is predicted that in 2030, PHEV will have the lowest LCCO2emissions, followed in order by HEV and BEV, as it is anticipated that nuclear and renewable energy sources will be widely available by 2030. PHEV is expected to gain popularity by 2030. Regarding BEV, large quantities of CO2emissions are emitted during battery production. Furthermore, due to the domestic electricity generation mix from the present day up to 2030, the LCCO2emissions of BEV will exceed those of HEV and PHEV.

This study was performed by the Oak Ridge National Laboratory (ORNL) to identify practical approaches, technical barriers, and cost impacts to achieving high-temperature coolant operation for certain traction drive subassemblies and components of hybrid electric vehicles (HEV). HEVs are unique in their need for the cooling of certain dedicated-traction drive subassemblies/components that include the electric motor(s), generators(s), inverter, dc converter (where applicable), and dc-link capacitors. The new coolant system under study would abandon the dedicated 65 C coolant loop, such as used in the Prius, and instead rely on the 105 C engine cooling loop. This assessment is important because automotive manufacturers are interested in utilizing the existing water/glycol engine cooling loop to cool the HEV subassemblies in order to eliminate an additional coolant loop with its associated reliability, space, and cost requirements. In addition, the cooling of power electronic devices, traction motors, and generators is critical in meeting the U.S. Department of Energy (DOE) FreedomCAR and Vehicle Technology (FCVT) goals for power rating, volume, weight, efficiency, reliability, and cost. All of these have been addressed in this study. Because there is high interest by the original equipment manufacturers (OEMs) in reducing manufacturing cost to enhance their competitive standing, the approach taken in this analysis was designed to be a positive 'can-do' approach that would be most successful in demonstrating the potential or opportunity of relying entirely on a high-temperature coolant system. Nevertheless, it proved to be clearly evident that a few formidable technical and cost barriers exist and no effective approach for mitigating the barriers was evident in the near term. Based on comprehensive thermal tests of the Prius reported by ORNL in 2005 [1], the continuous ratings at base speed (1200 rpm) with different coolant temperatures were projected from test data at 900 rpm. They are approximately 15 kW with 103 C coolant and 20 kW with 50 C coolant. To avoid this 25% drop1 in continuous power, design changes for improved heat dissipation and carefully managed changes in allowable thermal limits would be required in the hybrid subsystems. This study is designed to identify the technical barriers that potentially exist in moving to a high-temperature cooling loop prior to addressing the actual detailed design. For operation at a significantly higher coolant temperature, there were component-level issues that had to be addressed in this study. These issues generally pertained to the cost and reliability of existing or near term components that would be suitable for use with the 105 C coolant. The assessed components include power electronic devices/modules such as diodes and insulated-gate bipolar transistors (IGBTs), inverter-grade high-temperature capacitors, permanent magnets (PM), and motor-grade wire insulation. The need for potentially modifying/resizing subassemblies such as inverters, motors, and heat exchangers was also addressed in the study. In order to obtain pertinent information to assist ORNL researchers address the thermal issues at the component, module, subassembly, and system levels, pre-existing laboratory test data conducted at varying temperatures was analyzed in conjunction with information obtained from technical literature searches and industry sources.

This study was performed by the Oak Ridge National Laboratory (ORNL) to identify practical approaches, technical barriers, and cost impacts to achieving high-temperature coolant operation for certain traction drive subassemblies and components of hybrid electric vehicles (HEV). HEVs are unique in their need for the cooling of certain dedicated-traction drive subassemblies/components that include the electric motor(s), generators(s), inverter, dc converter (where applicable), and dc-link capacitors. The new coolant system under study would abandon the dedicated 65 C coolant loop, such as used in the Prius, and instead rely on the 105 C engine cooling loop. This assessment is important because automotive manufacturers are interested in utilizing the existing water/glycol engine cooling loop to cool the HEV subassemblies in order to eliminate an additional coolant loop with its associated reliability, space, and cost requirements. In addition, the cooling of power electronic devices, traction motors, and generators is critical in meeting the U.S. Department of Energy (DOE) FreedomCAR and Vehicle Technology (FCVT) goals for power rating, volume, weight, efficiency, reliability, and cost. All of these have been addressed in this study. Because there is high interest by the original equipment manufacturers (OEMs) in reducing manufacturing cost to enhance their competitive standing, the approach taken in this analysis was designed to be a positive 'can-do' approach that would be most successful in demonstrating the potential or opportunity of relying entirely on a high-temperature coolant system. Nevertheless, it proved to be clearly evident that a few formidable technical and cost barriers exist and no effective approach for mitigating the barriers was evident in the near term. Based on comprehensive thermal tests of the Prius reported by ORNL in 2005 [1], the continuous ratings at base speed (1200 rpm) with different coolant temperatures were projected from test data at 900 rpm. They are approximately 15 kW with 103 C coolant and 20 kW with 50 C coolant. To avoid this 25% drop1 in continuous power, design changes for improved heat dissipation and carefully managed changes in allowable thermal limits would be required in the hybrid subsystems. This study is designed to identify the technical barriers that potentially exist in moving to a high-temperature cooling loop prior to addressing the actual detailed design. For operation at a significantly higher coolant temperature, there were component-level issues that had to be addressed in this study. These issues generally pertained to the cost and reliability of existing or near-term components that would be suitable for use with the 105 C coolant. The assessed components include power electronic devices/modules such as diodes and insulated-gate bipolar transistors (IGBTs), inverter-grade high-temperature capacitors, permanent magnets (PM), and motor-grade wire insulation. The need for potentially modifying/resizing subassemblies such as inverters, motors, and heat exchangers was also addressed in the study. In order to obtain pertinent information to assist ORNL researchers address the thermal issues at the component, module, subassembly, and system levels, pre-existing laboratory test data conducted at varying temperatures was analyzed in conjunction with information obtained from technical literature searches and industry sources.

<div class="section abstract"><div class="htmlview paragraph">The success of improved fuel economy is the proper integration of thermal management components which are appropriately performed to reduce friction and wasted energy. The thermal management systems of vehicle are able to balance the multiple needs such as heating, cooling, or appropriate operation within specified temperature ranges of propulsion systems. Since the propulsion systems of vehicle have changed from a single energy source based on conventional internal combustion engine to hybrid system including more electrical system such as full type of hybrid electric vehicle or plug-in hybrid electric vehicles, a new transition associated with vehicle thermal management arises. More efficient thermal management systems are required to improve the fuel economy in the hybrid electric vehicles because of the driving of electric traction motor and the increase of engine off time. The decrease of engine operation time may not sustain the proper temperature ranges of engine and gearbox. As an engine starts at low ambient temperature, heat from the wasted heat of exhausted gas can be supplied not only to cabin heater, but also to engine and gearbox at initial warm-up.</div><div class="htmlview paragraph">To practically apply recent thermal management technologies in commercial use, improved performance for the low energy density per cost in a viable vehicle package is necessary in general. This research describes the one of cost effective thermal management solutions recovering exhaust gas heat exchanging system with coolant and gear box oil simultaneously. The previous type of recovering the exhaust heat is to exchange the heat between the coolant and the exhaust gas to increase the temperature of the engine coolant, thereby reducing the friction and improving the fuel efficiency. However, the reduction in engine friction loss and improvement of fuel economy remains low due to the short period of exchanging heat between exhaust gas and coolant. It is more advantageous to increase the temperature of the engine oil or gear box oil rather than to increase the coolant temperature. Accordingly, the developed exhaust heat recovery device which performs integral heat exchange of the exhaust gas heat of engine increases the temperature of the coolant and the gear box oil, thereby reducing friction loss and improving fuel economy. The experimental result of this system improved 2.5% of fuel economy at UDDS drive cycles.</div></div>

Design, demonstrations and sustainability impact assessments for plug-in hybrid electric vehicles

The growing interest in reducing fuel consumption and gas emissions provides an incentive for the automotive industry to innovate in the field of hybrid electric vehicles (HEV) and plug‐in hybrid electric vehicles (PHEV). The two embedded power sources in these vehicles require an intelligent controller in order to make the best decision on the power distribution. Actually these controllers, often called energy management systems, are very important and greatly influence the achievable fuel economy. Compared with an HEV, a PHEV allows battery discharge over a complete trip. As a consequence the optimal control of a PHEV implies a stronger dependence on the total driving cycle. Many authors have studied the possibility of fuzzy‐based systems for both HEV and PHEV as they have proved to be robust, reliable and simple. However, classical fuzzy rule‐based strategies demonstrate a lack of optimality because their design is focused on the actual vehicle state rather than the driving conditions. This study proposes a blended control strategy based on fuzzy logic for a PHEV. The proposed controller is fed with driving condition information in order to increase the controller effectiveness in every situation. The efficiency of the proposed controller is demonstrated through simulations.

This paper covers a comparative study on fuel economy and emissions of a conventional hybrid electric vehicle (HEV) and the UTS plug-in HEV (PHEV). The interaction between the components such as energy storage system, electric machine, power control unit and internal combustion engine of the UTS PHEV are complex in order to optimize the fuel economy and emissions brought by the vehicle. In this work, the model of the UTS PHEV is derived and implemented numerically in the MATLAB/SIMULINK environment to study its operational performance in various drive cycles measured under life conditions. The simulation results in terms of fuel economy and emissions of the series and parallel HEV from the Advanced Vehicle Simulator and UTS PHEV are compared and the pros and cons discussed.