Extended Range Electric Vehicle Research Articles

Development Progress on the Ceres Power Steel Cell Technology Platform: Further Progress Towards Commercialization

Ceres Power is continuing to make excellent progress in the development of its low-temperature metal supported SOFC design (the ‘Steel Cell’) based predominantly around the use of ceria. Major technological highlights over the last year include the completion of verification and validation testing on the latest (v4.0) version of the Steel Cell technology and its release to customers, the successful field-trial deployment of a fleet of SteelGen 700We micro-CHP demonstrator units as part of the European Ene.field program in partnership with British Gas. A higher-power SteelCell stack design is also under development for use in electric vehicle range extender applications, taking advantage of the outstanding thermal-cycling ability of the technology. The focus of technology development is to further improve stack power density, durability and efficiency. Significant progress has been demonstrated at the R&D level on all of these requirements, and the design improvements to achieve them will be incorporated into the next generation of SteelCell technology.

Study and Realization on Power Energy Distribution Control for Auxiliary Power Unit

This paper is focus on power energy distribution control of auxiliary power unit (APU) for a range-extended electric vehicle (RE–EV). Based on the working characteristic of the engine and the generator, a coordination control strategy of RE–EV is proposed. A regulating rule of APU control system speed and torque which meets the power demand of the RE–EV is designed. The PID and fuzzy control methods of engine speed are discussed by simulation analysis. In order to investigate the APU control processing, the incremental PID and fuzzy control algorithms are used to achieve speed control in the APU test bench. The influence on tuning parameters, control period and the working condition are analyzed from test results. The coordination control strategies of engine and generator are realized and verified by experimental research.

A study on the control strategy for range-extender in extended-range electric vehicle

A study on the control strategy for range-extender in extended-range electric vehicle

Design and Development of an All Solid State Lithium Sulfur Battery Using Ceramic Polymer Composite Solid Electrolyte

Currently widely used Lithium ion batteries are based on metal oxides or phosphates and carbon systems with theoretical specific capacity of about 400 Wh/Kg. However to meet the ever growing energy demand of modern society, specifically for extended range electric vehicles, high energy density batteries are required [1, 2]. From this viewpoint, the use of sulfur as a cathode material is highly beneficial since its theoretical specific capacity corresponding to 1675 mAh/g could generate high energy density of 2600 Wh/Kg which is 3x105 folds higher than the state-of-the art Lithium ion batteries [3]. However, research on lithium sulfur (Li/S) batteries using liquid electrolytes faces several problems such as the loss of the active material in the form of soluble polysulfide reaction products [4, 5]. Hence, for the development of next generation high performance power sources with high energy densities substantial emphasis has be laid on rechargeable all solid-state Li/S batteries. All solid state Li/S batteries include a solid electrolyte that offers several benefits such as good flexibility, potentially high electrochemical stability window and low flammability. The solid state nature could be very beneficial to Li/S batteries as they can prevent polysulfide dissolution and efficiently lessen dendrite penetration [6]. In this work, two kind of sulfur carbon composite electrodes were prepared by mechanical activation and thermal activation technique and the performance was evaluated by incorporating in a solid state battery. A composite solid polymer electrolyte prepared by dispersing the Li1.3Al0.3Ti1.7(PO4)3 (LATP) ceramic fillers in the blend of high and low molecular weights polymer matrix was used as a solid electrolyte. The solid state battery using thermally activated composite electrode showed good electrochemical performance and cycle stability due to intimate contact between the sulfur and the carbon. [1] Morris, R. Scott, et al. "High-energy, rechargeable Li-ion battery based on carbon nanotube technology." Journal of Power Sources 138.1 (2004): 277-280. [2] Thackeray, Michael M., Christopher Wolverton, and Eric D. Isaacs. "Electrical energy storage for transportation—approaching the limits of, and going beyond, lithium-ion batteries." Energy & Environmental Science 5.7 (2012): 7854-7863. [3] Aurbach, Doron, et al. "On the surface chemical aspects of very high energy density, rechargeable Li–sulfur batteries." Journal of the Electrochemical Society 156.8 (2009): A694-A702. [4] Hayashi, Akitoshi, et al. "All-solid-state Li/S batteries with highly conductive glass–ceramic electrolytes." Electrochemistry communications 5.8 (2003): 701-705. [5] Kobayashi, Takeshi, et al. "All solid-state battery with sulfur electrode and thio-LISICON electrolyte." Journal of Power Sources 182.2 (2008): 621-625. [6] Machida, Nobuya, et al. "Electrochemical properties of sulfur as cathode materials in a solid-state lithium battery with inorganic solid electrolytes." Solid State Ionics 175.1 (2004): 247-250.

Analysis of electric vehicle extended range misalignment based on rigid-flexible dynamics

The safety of the extended range electric vehicle is seriously affected by the misalignment fault. Therefore, this paper analyzed the electric vehicle extended range misalignment based on rigid-flexible dynamics. Through comprehensively applied the hybrid modeling of rigid-flexible and the method of fault diagnosis of machinery and equipment comprehensively, it established a extender hybrid rigid flexible mechanical model by means of the software ADAMS and ANSYS. By setting the relevant parameters to simulate the misalignment of shafting, the failure phenomenon, the spectrum analysis and the evolution rules were analyzed. It concluded that 0.5th and 1 harmonics are considered as the characteristic parameters of misalignment diagnostics for electric vehicle extended range.

A Proportional Resonant Control Strategy for Efficiency Improvement in Extended Range Electric Vehicles

The key to control the range extender generation system is to improve the efficiency and reduce the emissions of the electric vehicle (EV). In this paper, based on the purpose of efficiency optimization, both engine and generator are matched to get a public high efficiency region, and a partial power following control strategy was presented. The engine speed is constant in the defined power range, so the output power regulation of the range extender is only realized by the adjustment of the torque of the generator. Engine speed and generator torque were decoupled. An improved proportional resonant (PR) controller is adopted to achieve fast output power regulation. In order to ensure the response characteristics of the control system and to improve the robustness, the impacts on system’s characteristics and stability caused by PR controller and parameters in the inner-current loop were analyzed via frequency response characteristics. A pre-Tustin with deviation compensation is proposed for PR controller’s discretization. A stable and robust power following control method is obtained for the range extender control system. Finally, simulation and experiment of the proposed control strategy illustrated its feasibility and correctness.

Development of a range-extended electric vehicle powertrain for an integrated energy systems research printed utility vehicle

Rapid vehicle and powertrain development has become essential to for the design and implementation of vehicles that meet and exceed the fuel efficiency, cost, and performance targets expected by today’s consumer while keeping pace with reduced development cycle and more frequent product releases. Recently, advances in large-scale additive manufacturing have provided the means to bridge hardware-in-the-loop (HIL) experimentation and preproduction mule chassis evaluation. This paper details the accelerated development of a printed range-extended electric vehicle (REEV) by Oak Ridge National Laboratory, by paralleling hardware-in-the-loop development of the powertrain with rapid chassis prototyping using big area additive manufacturing (BAAM). BAAM’s ability to accelerate the mule vehicle development from computer-aided design to vehicle build is explored. The use of a hardware-in-the-loop laboratory is described as it is applied to the design of a range-extended electric powertrain to be installed in a printed prototype vehicle. The integration of the powertrain and the opportunities and challenges it presents are described in this work. A comparison of offline simulation, HIL and chassis rolls results is presented to validate the development process. Chassis dynamometer results for battery electric and range extender operation are analyzed to show the benefits of the architecture.

Experimental verification of a thermal equivalent circuit dynamic model on an extended range electric vehicle battery pack

Abstract The development of a dynamic thermal battery model for hybrid and electric vehicles is realized. A thermal equivalent circuit model is created which aims to capture and understand the heat propagation from the cells through the entire pack and to the environment using a production vehicle battery pack for model validation. The inclusion of production hardware and the liquid battery thermal management system components into the model considers physical and geometric properties to calculate thermal resistances of components (conduction, convection and radiation) along with their associated heat capacity. Various heat sources/sinks comprise the remaining model elements. Analog equivalent circuit simulations using PSpice are compared to experimental results to validate internal temperature nodes and heat rates measured through various elements, which are then employed to refine the model further. Agreement with experimental results indicates the proposed method allows for a comprehensive real-time battery pack analysis at little computational expense when compared to other types of computer based simulations. Elevated road and ambient conditions in Mesa, Arizona are simulated on a parked vehicle with varying quiescent cooling rates to examine the effect on the diurnal battery temperature for longer term static exposure. A typical daily driving schedule is also simulated and examined.

Power distribution of a co-axial dual-mechanical-port flux-switching permanent magnet machine for fuel-based extended range electric vehicles

In this paper, power distribution between the inner and outer machines of a co-axial dual-mechanical-port flux-switching permanent magnet (CADMP-FSPM) machine is investigated for fuel-based extended range electric vehicle (ER-EV). Firstly, the topology and operation principle of the CADMP-FSPM machine are introduced, which consist of an inner FSPM machine used for high-speed, an outer FSPM machine for low-speed, and a magnetic isolation ring between them. Then, the magnetic field coupling of the inner and outer FSPM machines is analyzed with more attention paid to the optimization of the isolation ring thickness. Thirdly, the power-dimension (PD) equations of the inner and outer FSPM machines are derived, respectively, and thereafter, the PD equation of the whole CADMP-FSPM machine can be given. Finally, the PD equations are validated by finite element analysis, which supplies the guidance on the design of this type of machines.

Design method of a power management strategy for variable battery capacities range-extended electric vehicles to improve energy efficiency and cost-effectiveness

Energy management strategy and battery capacity are the primary factors for the energy efficiency of range-extended electric buses (REEBs). To improve the energy efficiency of REEBs developed by Tsinghua University, an optimal design method of global optimization-based strategy is investigated. It is real-time and adaptive to variable traction battery capacities of series REEBs. For simulation, the physical model of REEB and key components are established. The optimal strategy is first extracted by the power split ratio (PSR) from REEB simulation result with dynamic program (DP) algorithm. The power distribution map is obtained by series simulations for variable battery capacity options. The control law for developing optimal strategy are achieved by cluster regression for power distribution data. To verify the effect of the proposed energy management strategy, characteristics of powertrain, energy efficiency, operating cost, and computing time are ultimately analyzed. Simulation results show that the energy efficiency of the global optimization-based strategy presented in this paper is similar to that of the DP strategy. Therefore, the overall energy efficiency can be significantly improved compared with that of the CDCS strategy, and operating costs can be substantially reduced. The feasibility of candidate control strategies is thereby assessed via the employment of variable parameters.

Modeling and Energy Management of an HCCI based Powertrain for Series Hybrid and Extended Range Electric Vehicles

Low temperature combustion (LTC) engines show promise for fuel economy improvement, however, these engines suffer from limited operating range. In this study, a specific type of LTC engine, known as homogeneous charge compression ignition (HCCI), is used in a series hybrid and extended range electric vehicle (E-REV) powertrain to investigate the ultimate fuel saving of a purely dedicated HCCI mode powertrain. Three types of energy management control (EMC) strategies including rule-based, dynamic programing (DP), and model predictive control (MPC) are designed and implemented. The simulation results show 17.7% fuel economy improvement in series HEV and 18.0% fuel economy improvement in E-REV compared to a conventional HEV using an SI engine in urban dynamometer driving schedule (UDDS) driving cycle. In addition, simulation results show that the HCCI fuel economy improvement increases in the driving cycles with greater base average power.

Modelling and energy management of an HCCI-based powertrain for series hybrid and extended range electric vehicles

Modelling and energy management of an HCCI-based powertrain for series hybrid and extended range electric vehicles

Assessing the effects of a growing electric vehicle fleet using a microscopic travel demand model

The German government seeks to increase the number of electric vehicles (EV) in the German car fleet to one million by 2020. Since some characteristics of EVs differ from conventional cars, there is an increasing need to assess the various impacts of a growing EV fleet. In this work, we have focused on possible effects related to the field of transport. We identified three important aspects and evaluated them over a period of one week using the microscopic travel demand model mobiTopp. First, we modelled the potential EV user groups of the near future by developing an EV user model; this model considers both interest in EVs and suitability for EV usage. Second, we simulated the travel behaviour of EV users; we used an EV usage model to consider the restrictions of EVs in choice decisions and also compared the usage behaviour of EV and conventional cars users. Third, we analysed the power consumption of the simulated EVs and evaluated the load peaks based on the simulated travel patterns. Our results indicate that a growing EV fleet implies a more heterogeneous distribution of EVs among car owners. They also indicate that the trip chain length of battery electric vehicles (BEVs) is much lower than that of extended range electric vehicles (EREVs) and conventional cars on average.

Research on Modeling Method of Power System Key Components for E-REV

Aiming at the modeling problem of power system key components for an Extended-Range Electric Vehicle (E-REV), the co-simulation platform based on AVL-Cruise and Matlab/Simulink software is introduced, and the modeling methods of E-REV engine, driving motor and battery are studies by the method of mixing the theoretical modeling with the experimental modeling. Off-line simulation results with chosen driving cycles indicate that the proposed vehicle model has better simulation precision and can meet the simulation specification of the E-REV dynamic performance.

Thermodynamic Model for Substitutional Materials: Application to Lithiated Graphite, Spinel Manganese Oxide, Iron Phosphate, and Layered Nickel-Manganese-Cobalt Oxide

We derive and implement a method to describe the thermodynamics of electrode materials based on a substitutional lattice model. To assess the utility and generality of the method, we compare model results with experimental data for a variety of electrode materials: lithiated graphite and layered nickel-manganese-cobalt oxide (Chevrolet Bolt Electric Vehicle negative and positive electrode materials, respectively), manganese oxide (in the positive electrodes of the Gen 1 and Gen 2 Chevrolet Volt Extended Range Electric Vehicle and the positive electrode of many high-power-density batteries), and iron phosphate (Gen 1 Chevrolet Spark Electric Vehicle positive electrode material and of immediate interest for 12 and 48 V applications). An early version of the model has been applied to lithiated silicon (Li-Si). As was found in the Li-Si study, the model enables one to quantitatively represent experimental data from these different electrode materials with a small number of parameters, and, in this sense, the approach is both general and efficient. An open question is the utility of controlled-potential vs. controlled-current experiments for the elucidation of the system thermodynamics. We provide commentary on this question, and we highlight other open questions throughout this work.

Magnetic flux analysis and performance test of permanent magnet and claw-pole electromagnetic hybrid excitation generator for electric vehicle range extender

Developed hybrid excitation generator (HEG) has a tangential permanent magnet (PM) and claw-pole electromagnetic parallel combined rotor and a fractional-slot winding stator, which makes stator core eddy-loss and armature winding copper-loss less. By establishing the equivalent magnetic circuit model of each part of HEG and analysing permeance influence factors, magnetic isolation measures are taken to reduce flux leakage and improve output efficiency. The designed electromagnetic coupling regulator controller can ensure stable voltage export of HEG in a wide range of speeds and load states by changing quantity and direction of excitation current to adjust the size of air gap magnetic flux density. Performance test is done and results show that the output voltage is relatively stable. So the HEG can provide electric energy to battery and electrical equipment of vehicles.

Review of the Fault Mechanism and Diagnostic Techniques for the Range Extender Hybrid Electric Vehicle

This paper presents a thorough literature review on the fault mechanism and diagnostic techniques for a range extender hybrid electric vehicle, which is one of the most feasible electric vehicles. However, extensive fault diagnosis research has been done on the diesel engine or a generator, but studies on the range extender are still limited, which is a coupling device of an engine-generator shaft. It has many coupling faults except to the single failure mode of the diesel engine or the generator. In this paper, the research development of the fault mechanism and fault diagnosis has been reviewed and analyzed. In addition, the trends in fault diagnosis technologies have been discussed, which provides a theoretical foundation for the engineering application of the condition monitoring and fault diagnosis of the electric vehicle range extender.

Magnetic flux analysis and performance test of permanent magnet and claw-pole electromagnetic hybrid excitation generator for electric vehicle range extender

Magnetic flux analysis and performance test of permanent magnet and claw-pole electromagnetic hybrid excitation generator for electric vehicle range extender

Structure Evolution and Thermal Stability of High-Energy- Density Li-Ion Battery Cathode Li2VO2F

Lithium-ion batteries (LIBs) provide high-energy-density electrochemical energy storage, which plays a central role in advancing technologies ranging from portable electronics to electric vehicles (EVs). However, a demand for lighter, more compact devices and for extended range EVs continues to fuel the need for higher energy density storage systems. Li2VO2F, which is synthesized in its lithiated state, allows two-electron transfer per formula during the electrochemical reaction providing a high theoretical capacity of 462 mAh/g. Herein, the synthesis and electrochemical performance of Li2VO2F are optimized. The thermal stability of Li2VO2F, which is related to the safety of a battery is studied by thermal gravimetric analysis. The structure and vanadium oxidation state evolution along Li cycling are studied by ex-situ X-ray diffraction and absorption techniques. It is shown that the rock-salt structure of pristine Li2VO2F is stable up to at least 250°C, and is preserved upon Li cycling, which proceeds by the solid-solution mechanism. However, not all Li can be removed from the structure upon charge to 4.5 V, limiting the experimentally obtained capacity.

Fuel consumption and CO2 emission investigation of range extender with diesel and gasoline engine

Range extender engine is one of the main components of the range-extended electric vehicle (REEV) and together with a generator to extend the mileage of the electric vehicle. The main component of REEV is an electric motor, battery, and generator set that consist of generator and engine. In this study, we compared two models of REEV performance with two different types of the engine by simulation. Single cylinder 499 cc gasoline engine and single cylinder 667 cc diesel engine are chosen as the object of this research especially relating to the utilization of the fuel consumption and CO2 emissions when fitted to an electric vehicle. The simulation was conducted by using AVL Cruise software and performed by entering the data, both experiment and simulation data, on all the main components of REEV. This simulation was performed in Japan 08 driving cycle. Based on the simulation, fuel consumption is reduced up to 35.59% for REEV with single cylinder diesel engine 667 cc compared to REEV with single cylinder gasoline engine 499 cc. The reduction of CO2 emissions from REEV with single cylinder 499 cc gasoline engine compared to REEV with single cylinder 667 cc diesel engine up to 30.47%.