Electric Vehicle Power Supply Research Articles

Efficient, Secure, and Privacy-Preserving PMIPv6 Protocol for V2G Networks

To ensure seamless communication between mobile electric vehicles (EVs) and EV power supply equipment, support for ubiquitous and transparent mobile IP communications is essential in vehicle-to-grid (V2G) networks. However, it initiates a range of privacy-related challenges as it is possible to track connected EVs through their mobile IP addresses. Recent studies are mostly dedicated to solving authentication and privacy issues in V2G networks in general. Yet, they do not tackle the security and privacy challenges resulting from enabling mobile IP communications. To address these challenges, this paper proposes an efficient, secure, and privacy-preserving proxy mobile IPv6 (ESP-PMIPv6) protocol for the protection of mobile IP communication in V2G networks. ESP-PMIPv6 enables authorised EVs to acquire a mobile IPv6 address and access the V2G network in a secure and privacy-preserving manner. While ESP-PMIPv6 offers mutual authentication, identity anonymity, and location unlinkability for the mobile EVs, it also achieves authorised traceability of misbehaving EVs through a novel collaborative tracking scheme. Formal and informal security analyses are conducted to prove that ESP-PMIPv6 meets these security and privacy goals. In addition, via a simulated assessment, ESP-PMIPv6 is proven to achieve low authentication latency, low handover delay, and low packet loss rate in comparison with the PMIPv6 protocol.

Pentafluorophenyl Isocyanate As Effective Electrolyte Additive for Improved Performance of Silicon-Based Lithium Ion Full Cells

Lithium ion batteries (LIBs) are considered as key technology for stationary energy storage systems and especially as power supply for electric vehicles (EVs). Even though LIBs are already used in EVs, there is a need of further improvements of the LIBs to achieve driving ranges of more than 500 km, what is considered to be a value for greater consumer acceptance of EVs. To reach this goal, the specific energy and energy density of LIBs need to be increased to approximately 350 Wh kg-1 and 750 Wh L-1 at cell level, respectively. The use of alternative anode materials to replace the state-of-the-art graphite anode, is considered as an efficient strategy to increase the energy density of LIBs. Silicon (Si) turns out to be the most promising material for advanced anodes in LIBs, as it offers a nearly 10 times higher specific capacity compared to graphite. However, the implementation of electrode materials containing contents of more than 5-10% Si in commercial LIBs is still hampered by huge volume changes leading to a continuous solid electrolyte interphase (SEI) re-formation, loss of active lithium and, therefore, to a poor capacity retention.[1] The application of nano-sized Si materials like nanoparticles, nanowires or thin films is reported to significantly improve the performance of Si based anodes, due to better accommodation of the huge volume changes upon lithiation/de-lithiation. Additionally, Si thin film electrodes exhibit improved specific capacities in comparison to typical composite-based electrodes, because of the absence of inactive components like binder and conductive additives.[2] An additional approach to improve the performance of Si based electrodes is the addition of additives to the electrolyte. Electrolyte additives like fluoroethylene carbonate (FEC) and vinylene carbonate (VC) are commonly known to enhance the capacity retention of Si electrodes by forming a more stable SEI, thus, preventing ongoing electrolyte decomposition and continuous active lithium loss.[3] Isocyanate compounds are able to undergo reductive polymerization and, therefore, may be considered as effective electrolyte additives for Si anodes. Actually, several isocyanates were reported to function as effective film-forming additives for graphite-based negative electrodes.[4] Within this work, magnetron sputtering was utilized for the preparation of thin film Si anodes, which contain neither a binder nor a conductive agent. Therefore, the effect of the electrolyte additive can be directly related to the Si active material. Since it was recently reported, that lithium consumption related to SEI reformation is the main failure mechanism of lithium ion full cells containing a Si anode[5], the electrochemical performance of these Si thin film electrodes was investigated in Si/NMC-111 full cells using different electrolyte formulations. DFT calculations (HOMO/LUMO energies) were performed prior to electrochemical investigations for reductive and oxidative stability predictions of the electrolyte solvent and additive molecules. The addition of the pentafluorophenyl isocyanate electrolyte additive leads to an increased Coulombic efficiency and a significantly enhanced capacity retention of the LIB full cells during prolonged cycling, in comparison to the baseline electrolyte. Post-mortem investigations of the negative Si electrodes by means of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were performed to study the SEI layer, formed in the different electrolyte formulations. The enhanced cycling performance of the full cells can be correlated to an improved SEI formation. Reference s : [1] D. Andre, H. Hain, P. Lamp, F. Maglia, B. Stiaszny, Future high-energy density anode materials from an automotive application perspective, Journal of Materials Chemistry A, 5 (2017) 17174-17198. [2] M.N. Obrovac, V.L. Chevrier, Alloy Negative Electrodes for Li-Ion Batteries, Chemical Reviews, 114 (2014) 11444-11502. [3] S. Dalavi, P. Guduru, B.L. Lucht, Performance Enhancing Electrolyte Additives for Lithium Ion Batteries with Silicon Anodes, Journal of The Electrochemical Society, 159 (2012) A642-A646. [4] C. Korepp, W. Kern, E.A. Lanzer, P.R. Raimann, J.O. Besenhard, M.H. Yang, K.C. Möller, D.T. Shieh, M. Winter, Isocyanate compounds as electrolyte additives for lithium-ion batteries, Journal of Power Sources, 174 (2007) 387-393. [5] M. Klett, J.A. Gilbert, S.E. Trask, B.J. Polzin, A.N. Jansen, D.W. Dees, D.P. Abraham, Electrode Behavior RE-Visited: Monitoring Potential Windows, Capacity Loss, and Impedance Changes in Li1.03(Ni0.5Co0.2Mn0.3)0.97O2/Silicon-Graphite Full Cells, Journal of The Electrochemical Society, 163 (2016) A875-A887.

The neutral point-potential and current model predictive control method for Vienna rectifier

A three-phase three-level Vienna rectifier has been widely used in the front-end PFC modules of electric vehicle and data center DC power supply system with the advantages of without dead-time, low switch voltage stress and small grid current harmonic. However, to achieve unity power factor and alleviate specific harmonic pollution, its controller design becomes more complex. Therefore, a novel finite control set model predictive control strategy is presented. The behavior of the output voltage is firstly predicted for each possible switching state in each sampling interval based on the model of a Vienna rectifier. Besides, the midpoint voltage imbalance and time delay caused by the calculation may deteriorate the grid current or even damage the device seriously. Thus, a cost function is first built to balance the neutral-point-potential voltage. After then, the cost function is updated by considering the delay caused by the calculation, sampling and gate driver. Compared with the conventional PI-SVM control strategy, the effectiveness of the proposed model predictive control strategy is validated by both the simulation and experimental results.

Integrated Multiple-Output Synchronous Buck Converter for Electric Vehicle Power Supply

This paper proposes a novel integrated synchronous buck converter for the auxiliary power supply system of electric vehicles, which achieves multiple independently regulated outputs with reduced switching components in comparison with the conventional separate buck converters. In order to obtain a better understanding of the proposed converter, operational principle and performance characteristics of a simplified dual-output buck converter are introduced in detail, as an example. The analysis shows that zero-voltage-switching operation and lower conduction losses could be attained. In addition, its dynamic behavior is similar to the conventional buck converter and thus the controller design is simple. Finally, experimental results based on a prototype circuit in which two inductors are integrated into one magnetic core to achieve further reduced cost are demonstrated to verify the advantages.

Development of Metallic Bipolar Plate for PEFC By Coating Carbon Thin Film on Stainless Steel

Introduction The polymer electrolyte fuel cell (PEFC) has characteristics that it can operate at a relatively low temperature and can be downsized. Therefore, development is proceeding in a wide field such as a stationary power supply and a power supply for electric vehicles. It is required to reduce the size and weight of the fuel cell as well as to lower the price. For example, it is a method to solve by changing the separator material from a conventional carbon material to a metallic material. Therefore, in this research we proposed the following method aiming at the development of simple and low cost production method. The method is to coat the surface of stainless steel with a resin thin film and then carbonize it at low temperature. We observed the surface and cross section of the obtained carbon film using high resolution SEM. We also examined its applicability as a fuel cell separator by measuring Raman spectroscopy, TG-DTA, XRD, XPS and so on. Experimental method The substrate materials used were austenitic SUS304 stainless steel with various thicknesses. Surface pretreatment of the specimen was polished with wet emery paper up to #600. Also, it was used without pretreatment. In the experiment, specimens were used which was rinsed with water after degreasing with acetone before use. The resin coating on the specimen surface was carried out by electrodeposition coating method using various cationic resins. Electrodeposition coating was carried out with varying electrolytic voltage and time at 303K. Carbonization of the resin film was performed in an electric furnace under a nitrogen atmosphere. Sintering temperature was 673K to 1173K for 2 hours. The electrical properties of the carbon-coated film were evaluated by measurement of electrical conductivity. Electrochemical properties were evaluated by measurement of polarization curve. The polarization curves were measured by linear sweep polarization method with sweep rate of 20 mV / min at room temperature in 0.5M H2SO4 solution by a three electrode system using a working(specimen) electrode, a platinum plate as a counter electrode and Hg/Hg2SO4 electrode as a reference electrode. The electric resistance of the carbon film formed on the specimen surface by the carbonization treatment was measured and evaluated by the four-terminal sensing method. Results and discussion Figure 1 shows resin coated and its converted carbon film deposited on the specimen surface and cross section SEM photographs. The thickness of resin coated film with about 40 µm was reduced about 2 µm when sintered at 873K. The carbonized film had a smooth surface and no defects were observed. As a result of the tape peeling resistance test, resistance to the adhesion between the carbonized coating film to the substrate had a sufficient ability. This result seems to be due to the formation of the third layer which improves the adhesion at the interface between the substrate metal and the formed carbon film. Figure 2 shows the relationship between the electrical conductivity of the carbon film obtained by heat-treating the resin film formed on the specimen surface of various resin materials at 773 to 1173K and sintering temperature. The electrical resistance of sintered film decreased with increasing heat treatment temperature. And it showed under 10 mΩ·cm at 1073K. In order to improve the electrical conductivity at lower temperature treatment, a coating was prepared by mixing various kinds of carbon powder with resin. As a result, even in the heat treatment at 873K, a value of 10 mΩ·cm or less was obtained. Figure 3 shows polarization curves of specimens that are raw materials and covered by carbon thin film on specimen surface. The polarization curve of the untreated specimen showed an immersion potential of about 0.0 V(vs. SHE) and a passivation current density of 20 µA/cm2. On the other hand, the immersion potential in all carbon-coated specimens was 0.5 to 0.8 V(vs. SHE) and shifted in the noble direction and the anode current became 10 µA/cm2 or less. It was revealed that sufficient corrosion resistance and electric conductivity are exhibited by giving carbon coating treatment. The power generation test was carried out for 180 hours by connecting a load resistance of 0.1 Ω with a carbon film coated separator, as the result the generated voltage was approximately constant value of about 0.7 V during the test period. Therefore, it was clarified that the prepared separator is effective as a fuel cell separator. We intend to make a detailed presentation on the relation between the electrical conductivity and the corrosion resistance. This work was carried out with the assistance of the NEDO. Figure 1

Human Exposure to Electromagnetic Fields from Parallel Wireless Power Transfer Systems.

The scenario of multiple wireless power transfer (WPT) systems working closely, synchronously or asynchronously with phase difference often occurs in power supply for household appliances and electric vehicles in parking lots. Magnetic field leakage from the WPT systems is also varied due to unpredictable asynchronous working conditions. In this study, the magnetic field leakage from parallel WPT systems working with phase difference is predicted, and the induced electric field and specific absorption rate (SAR) in a human body standing in the vicinity are also evaluated. Computational results are compared with the restrictions prescribed in the regulations established to limit human exposure to time-varying electromagnetic fields (EMFs). The results show that the middle region between the two WPT coils is safer for the two WPT systems working in-phase, and the peripheral regions are safer around the WPT systems working anti-phase. Thin metallic plates larger than the WPT coils can shield the magnetic field leakage well, while smaller ones may worsen the situation. The orientation of the human body will influence the maximum magnitude of induced electric field and its distribution within the human body. The induced electric field centralizes in the trunk, groin, and genitals with only one exception: when the human body is standing right at the middle of the two WPT coils working in-phase, the induced electric field focuses on lower limbs. The SAR value in the lungs always seems to be greater than in other organs, while the value in the liver is minimal. Human exposure to EMFs meets the guidelines of the International Committee on Non-Ionizing Radiation Protection (ICNIRP), specifically reference levels with respect to magnetic field and basic restrictions on induced electric fields and SAR, as the charging power is lower than 3.1 kW and 55.5 kW, respectively. These results are positive with respect to the safe applications of parallel WPT systems working simultaneously.

Combined Optimal Sizing and Control of Li-Ion Battery/Supercapacitor Embedded Power Supply Using Hybrid Particle Swarm–Nelder–Mead Algorithm

This paper examines and optimizes parameters that affect the sizing and control of a hybrid embedded power supply composed of Li-ion batteries and supercapacitors in electric vehicle applications. High demands including power and energy density, low charge/discharge power stress on the battery (long lifetime), lightweight design, and relatively modest cost at the same time cannot be provided solely by batteries or supercapacitors. For this reason, we propose the use of a Li-ion battery/supercapacitor hybrid embedded power supply for an urban electric vehicle. The sizing process of this system including the optimization of the power sharing is done thanks to a developed hybrid Particle Swarm–Nelder–Mead algorithm involving multi-objective optimization. This approach also allows us to optimize the proposed energy management strategies based on frequency rule-based control and different ways of supercapacitors energy regulation. Obtained results show that the hybrid embedded power supply with the proposed control strategies is able to offer the best performances for the chosen electric vehicle in terms of weight, initial cost, and battery lifetime.

An Energy Management Study on Hybrid Power of Electric Vehicle Based on Aluminum Air Fuel Cell

With the continuous development of electric vehicles, the demand for electric vehicle power supply is becoming more and more urgent. In order to meet the needs of both energy and power, the hybrid power supply of aluminum air fuel cell and the supercapacitor is studied in this paper, and the matching parameters are analyzed and calculated. Then the hybrid power energy allocation strategy including the logic threshold control strategy and the fuzzy logic control strategy are provided. Finally, the power performance simulation is carried out under the actual conditions according to the two different strategies. It is shown that the fuzzy logic control strategy is superior to the logic threshold control strategy in the aspect of energy distribution.

Development of Lithium-Ion Battery with New Shutdown System Using Redox-Shuttle Compound

Lithium ion batteries (LIB) have been adopted for the power supply of electric vehicles, and higher energy density and larger capacity cells are now in demand. Complying with these demands means that cells under abnormal conditions could become less safe. In particular, the amount of heat due to cathode decomposition could increase if overcharged. Therefore, technology is necessary to improve the safety in overcharging conditions. A redox-shuttle compound is known as an effective protection technology for overcharging cells. A redox-shuttle compound can be reversibly oxidized and reduced at a defined potential slightly higher than the full-charge potential of the surface of cathode active materials. The oxidized redox-shuttle molecules that diffuse through the electrolytes would be reduced to their neutral state on the surface of anode active materials. Neutral molecules would then diffuse back to the cathode and be oxidized again. This shuttle reaction can convert excess energy during overcharging into heat, thereby protecting the cells by limiting the potential of the cathode to less than or equal to the oxidation potential of the shuttle molecules. However, when the overcharge current is bigger than the maximum rate of the shuttle reaction, the redox-shuttle compound cannot fully consume the current, and cathode active materials will be damaged. We designed and studied a new shutdown system that is a combination of a redox-shuttle compound and shutdown separator. In this system, the redox-shuttle compound will protect cathode active materials from overcharging, and at the same time, the separator will shut down because of the heat generated by the redox-shuttle reaction. First of all, we studied the rate of redox reaction and the temperature of the cell heated by the reaction of the redox-shuttle compound. We selected 1,4-di-tert-butyl-2,5-dimethoxybenzene as the redox-shuttle compound. The reaction potential of this material is about 3.9 V vs. Li/Li+ (From the point of view of the principle verification, we selected the redox-shuttle compound of a lower reaction potential to reduce the extra reaction while the redox-shuttle compound was reacting). The redox-shuttle compound was dissolved up to 0.15 M with a common electrolyte, EC/DEC (3/7 by volume)/ 1.0 M LiPF6 and used as a redox-shuttle electrolyte. Graphite and a mixture of lithium manganese oxide and lithium nickel oxide were used as the anode and cathode active material, respectively. Porous polypropylene (PP) and PP/polyethylene (PE)/PP stacked film were used as the separator. The melting points of PP and PE are 160°C and 130°C, respectively. Cells that varied in capacity from 3.5 to 10 Ah were prepared by changing the number of stacked layers (the size of the electrode was fixed). Each cell was charged at the rate of 0.1 to 1 C, and the cell voltage and the temperature on the surface of the cell were measured. As a result, as the cells were charged, a plateau was observed around 3.8 V of cell voltage, and the temperature of the cells increased at the same time. These results indicate that the redox-shuttle compound consumed current and converted it into heat. The increase in temperature of the cells heated by the redox-shuttle compound had a linear relationship with the charged current value (See figure 1). From this relational expression, when the charge current is higher than 10 A, the temperature of the cell can exceed 160°C (higher than the melting point of PP and PE), and ion diffusion will be protected. These results and equation suggest that the new shutdown system is capable of keeping the high energy density cells safe. On the meeting day, we will report the details of the new shutdown system and the results of the experiment using 10-Ah class cells. In particular, we will focus on the influence of the redox-shuttle reaction rate and the properties of the electrode and separator in this system.Fig. 1 Relationship between the charging current and the highest and equilibrium temperature on the surface of the cell. Figure 1

Intrinsic Electrochemical Characteristics of LiNi0.5Mn1.5O4 Spinel Synthesized By Flux Method

Lithium-ion batteries (LIBs) with high gravimetric and volumetric energy density are very important key devices for a power supply of plug-in hybrid electric vehicles (PHEVs) and electric vehicles (EVs). Much higher energy density is extensively demanded to increase the mileage per charge. Current LIBs utilize the composite electrodes which include active materials, binders, conductive agents, and current collector. The electrochemical characteristics of the composite electrode must be affected by the “composite” state (kinds of materials, mixing ratio, thickness, and tap density). It is difficult to distinguish the electrochemical characteristics of only active materials from that of the composite electrode. However, the intrinsic properties of active materials are very important to evaluate the electrode performance and understand the mechanism of the charging and discharging reaction. In this study, the single particle measurement technique was applied to study the intrinsic electrochemical characteristics of LiNi0.5Mn1.5O4 spinel (LNMO) synthesized by the flux method. This LNMO particles are aggregates of primary particles with from sub-micro to several micro-meter size, as shown in Fig.1. Fig.1 shows that the primary particles of LNMO are crystalline particles. This research will discuss the relationship between the electrochemical characteristics and the crystallinity, e.g. shape, orientation, and surface crystal plane. The details of the single particle measurement equipment were described elsewhere [1]. The two-electrode electrochemical cell was placed on the stage of an optical microscope. Glass coating Au wire (f =10 mm) was used as the micro-probe for the measurement. The electrolyte was mainly 1M LiPF6-EC:PC=1:1. In some measurement, FEC and other solvent were added to study the side reaction. The charging and discharging tests were conducted in the range from 3.4 V to 4.9 V vs. Li metal counter electrode by using a SP-150 (Biologic) with low current probe. After the electrochemical measurements, the measured particle was picked up by micro-tweezers and transferred to micro-Raman, SEM, FIB-SEM and TEM. This transfer procedure was done by using a transfer vessel in order to prevent the atmosphere exposure.Fig.2 shows the discharge rate characteristics of one LNMO particle. The discharge currents were changed from 0.2 nA to 2 nA while the charging current was fixed to be 0.2 nA. If the discharge capacity at 0.2 nA is assumed to be full capacity of the particle, 0.2 nA is corresponding to about 11 C-rate. Therefore, 2.0 nA is about 110 C-rate. The discharge capacity at 110 C-rate was kept over 80% of the capacity at 0.2 nA. The LNMO particles have excellent discharge rate characteristics although the initial irreversible capacity was quite high. In this presentation, the detailed results about not only electrochemical characteristic but also Raman, SEM and TEM analysis will be delivered.

Rechargeable lithium semi-flow battery using Li7P3S11

Rechargeable batteries play a pivotal role in conversion of chemical energy to electrical energy and energy storage. Lithium batteries have been considered as promising power supply for various electric vehicles and grid storage systems. However, the formation of lithium dendrites and use of liquid electrolytes turned out to be the major impediment in realising the potential of these batteries. To overcome these challenges here we demonstrate the use of various fast-ion conducting solids as solid electrolytes in semi-flow Li–S batteries containing catholyte slurries. Lithium conducting Li7P3S11 was prepared using ball- milling followed by annealing at 250°C. Rietveld refinements of compounds indicated that the product is Li7P3S11 with space group P-1 and lattice parameters of a=12.42(2) Å, b=6.066(9) Å, c=12.52(8) Å. The Li7P3S11 produced exhibits an ionic conductivity of the order of 7.1×10−4S/cm at 30°C. Here, we investigate the stability of these solid electrolytes in contact with catholytes consisting of polysulfide, Li2S8, dissolved in monoglyme. Li2S8/Li7P3S11/Li semi-flow rechargeable battery exhibited an initial discharge specific capacity of 1268mAh/g at 1C rate and retained 748mAh/g after the 10th cycle.

Intrinsic Electrochemical Properties of LiNi0.5Mn1.5O4 Synthesized By Flux Method for High Energy Density Li-Ion Batteries

Lithium-ion batteries (LIBs) with high gravimetric and volumetric energy density are very important key devices for the establishment of the sustainable energy system which is consisted of solar cells, wind power generations, smart grid, and batteries. In addition, the LIBs are extensively expected for a power supply of plug-in hybrid electric vehicles (PHEVs) and electric vehicles (EVs). Much higher energy density is needed to increase the mileage per charge. Current LIBs use the composite electrodes which are composed of active materials, binders, conductive agents, and current collector. The charging and discharging performance of the composite electrode must be affected by the “composite” state (kinds of materials, mixing ratio, thickness, and tap density). In addition to that, the materials which have large volume change during the charging and discharging are strongly affected by the state of the composite electrode. It is difficult to distinguish the electrochemical characteristics of only active materials from that of the composite electrode. However, the intrinsic properties of active materials are very important to evaluate the electrode performance and understand the mechanism of the charging and discharging reaction. In this study, the single particle measurement technique was used to study the intrinsic characteristics of LiNi0.5Mn1.5O4 (LNMO) synthesized by the flux methods. This LNMO particles were coated by NbOx nano-sheets for preventing the oxidation of electrolytes. Fig.1 shows the schematic diagram of the single particle measurement equipment. The two-electrode electrochemical cell was placed on the stage of an optical microscope. Glass coating Au wire (φ=10 μm) was used as the micro-probe for the measurement. The electrolytes were 1M LiPF6-EC:PC=1:1, 1M LiBF4-EC:PC=1:1, 1M LiPF6-FEC, and 1M LiBF4-FEC. The electrochemical measurement was conducted in the range from 3.0 V to 4.9V vs. Li metal counter electrode. After the electrochemical measurement, the measured particle was picked up by micro-tweezers and transferred to SEM, FIB-SEM and TEM. This transfer procedure was done by using transfer vessel in order to prevent the atmosphere exposure.Fig.2 shows the SEM image and EDS mapping images of the LNMO coated by NbOx nanosheet. Small crystallines coagulate to form large secondary particles. The secondary particle is about 5 ~ 20 μm, and adequate for single particle measurement. Nb was also detected due to the coverage by NbOx nanosheets. Further characterization by XRD and Raman spectroscopy was also conducted. The detailed results will be shown in the presentation.Fig. 3 demonstrates the charging and discharging curves of one NbOx coated LNMO particle in LiBF4-FEC electrolyte solution. The applied current is 1 nA. There is voltage plateau at about 4.75V because of Ni2+/Ni4+ redox, and the Mn3+/Mn4+ redox plateau is not appeared. The 2nd charging and discharging curve is almost same with 1st curve. Therefore, this NbOx coated LNMO particle has very good electrochemical performance as high voltage cathode material. However, the coulomb efficiency is 88% and 90% for 1st and 2nd cycle respectively. This irreversible capacity would be induced by the surface irreversible reaction at not only LNMO particle surface but also the Au micro-probe surface. In order to reveal the degradation mechanism of LNMO, the measured particle is picked up by micro-tweezers to analyze the particle by Raman-Spectroscopy, SEM, and TEM without atmosphere exposure. Based on those knowledge, we would like to discuss the detailed charging and discharging mechanism of LNMO. Figure 1

Mathematical design and analysis of anti-lock brake system for electric vehicle based on brake-by-wire technology

The current study presents the derivation of mathematical modelling of anti-lock brake system solely from brake-by-wire perspective. The study also proposes permanent magnet DC (PMDC) motor to perform suitable braking action which is selected based on predetermined electric actuator characteristics. The brake system and electric motor specifications are then designed, taking into consideration maximum magnitude of electric vehicle power supply. In addition to that, a study case based on proportional integral derivative (PID) controller is carried out to further examine performance behaviour of the proposed mathematical model and the validity of computational specifications for brake system design as well as the PMDC motor. Simulation analysis and investigation which are conducted in MATLAB software revealed efficient operating brake system that leads to obtain desired control signal successfully with outstanding performance. Furthermore, the result output behaviour of the plant mimics predetermined brake system analysis which ensures the validity of the proposed mathematical design.

The Research Status and Development Trend of Electric Vehicle Power Supply Technology

Electric vehicle (EV) power supply infrastructure construction and the related technologies are the prerequisite and core of the EV industry development respectively. This paper introduces the technology research and application situation of charging, battery swapping and smart charging/battery swap service network operation management in China, and meanwhile introduces the EV energy supply infrastructure construction and some typical pilot projects in China. And the EV energy supply technologies development trend is discussed at last.

The Research Status and Development Trend of Electric Vehicle Power Supply Technology

Electric vehicle (EV) power supply infrastructure construction and the related technologies are the prerequisite and core of the EV industry development respectively. This paper introduces the technology research and application situation of charging, battery swapping and smart charging/battery swap service network operation management in China, and meanwhile introduces the EV energy supply infrastructure construction and some typical pilot projects in China. And the EV energy supply technologies development trend is discussed at last.

Single Particle Measurement for Volume Change Behavior of a Silicon Single Particle

Lithium-ion batteries (LIBs) with high gravimetric and volumetric energy density are very important key devices for the establishment of the sustainable energy system which is consisted of solar cells, wind power generations, smart grid, and batteries. In addition, the LIBs are extensively expected for a power supply of plug-in hybrid electric vehicles (PHEVs) and electric vehicles (EVs). Much higher energy density is needed to increase the mileage per charge. Current LIBs use the composite electrodes which are composed of active materials, binders, conductive agents, and current collector. The charging and discharging performance of the composite electrode must be affected by the “composite” state (kinds of materials, mixing ratio, thickness, and tap density). In addition to that, the materials which have large volume change during the charging and discharging are strongly affected by the state of the composite electrode. It is difficult to distinguish the electrochemical characteristics of only active materials from that of the composite electrode.However, the intrinsic properties of active materials are very important to evaluate the electrode performance and understand the mechanism of the charging and discharging reaction. In this study, the single particle measurement technique was used to study the electrochemical lithiation of silicon single particle. This technique is very useful to measure the intrinsic properties of single particle of the active materials in the actual liquid electrolyte. Our group has reported that some positive electrode active materials have very good rate characteristics [1,2]. The microelectrode with 20 mm diameter is used as the micro probe to contact and apply the electrochemical technique to the one active material particle. The electrodeposited Cu covers the tip of the micro probe because the Cu is stable against the electrode potential of the lithiation of silicon. Our previous study has reported that this technique is applicable to measure the volume expansion of silicon single particle during the lithiation [3]. Figure 1 shows the drastic volume expansion behavior of a silicon single particle during the lithiation. A silicon particle contacted with micro-probe was expanding with the lithiation. The apparent volume expansion ratio is larger than the theoretical expectation. So far, we estimate that the reasons are the aggregation state of the silicon particle, the emergence of amorphous phase of the lithiated silicon and anisotropic properties of volume change. In order to discuss the reason of larger volume expansion and volume change mechanism of the silicon particle more precisely, micro-tweezers system was used to move the silicon particle to SEM observation and Raman spectroscopy measurement after the 1st charging by the single particle measurement technique. Some researchers use an in-situ TEM technique in order to understand the mechanism of silicon lithiation and delithiation [4]. This excellent technique can observe the silicon volume change behavior accompanied with the lithiation and delithiation with very high magnification, but it needs high vacuum condition. The advantage of our technique is the electrochemical condition is very near to the actual LIBs. Therefore, it is important to combine their knowledge and our results to find the volume change mechanism of silicon electrode during the lithiation and delithiation. In this presentation, we would like to discuss the comparison.Furthermore, high capacity active materials which have volume change during charging and discharging need the way to restrict or accommodate the volume change for the usage to practical battery electrodes. From the viewpoint of such approach, the binder effect is very important. A small piece of composite electrode with 20~40 mm was picked up to measure the electrochemical characteristics in the single particle measurement system. Comparing with the pristine silicon particle measurement results, we would like to discuss the binder effect to volume change behavior. References (1) K. Dokko, N. Nakata, K. Kanamura, J. Power Sources 189, 783 (2009)(2) H. Munakata, B. Takemura, T. Saito, K. Kanamura, J. Power Sources 217, 444 (2012)(3) K. Nishikawa, H. Munakata, K. Kanamura, J. Power Sources 243,630 (2013) [4]. M. T. McDowell, S. W. Lee, J. T. Harris, B. A. Korgel, C. Wang, W. D. Nix, and Y. Cui, Nano Lett., 13, 758 (2013)Figure 1. Volume expansion behavior of silicon single particle during the first lithiation

The Research Status and Development Trend of Electric Vehicle Power Supply Technology

Electric vehicle (EV) power supply infrastructure construction and the related technologies are the prerequisite and core of the EV industry development respectively. This paper introduces the technology research and application situation of charging, battery swapping and smart charging/battery swap service network operation management in China, and meanwhile introduces the EV energy supply infrastructure construction and some typical pilot projects in China. And the EV energy supply technologies development trend is discussed at last.

A Flyback 25W Switching Power Supply for Electric Vehicle

In order to keep the stability of the control circuit of electric vehicle, a flyback switching power supply was designed in this paper. The flyback switching power supply adopting current control mode PWM chip UC3842, and the output power of flyback switching power supply is 25W. In the design process of flyback switching power supply, the component parameters of control loop are worked out thoroughly. The flyback transformer was designed by considering the maximum pressure value of power switch. From the experimental results, the flyback switching power supply can work stably in the full load condition. The flyback switching power supply has excellent stability and dynamic characteristics.

Discussion on Operation Modes to the Electric Vehicle Charging Station

Electric vehicle charging station provides power supply for electric vehicles running, and it is the most important supporting infrastructure of electric vehicles. The article analyses three modes of electric vehicle charging station charging methods, discusses the advantages and disadvantages of each model, gives the developing trend of the pattern of the operation of electric vehicles, and provides some effective suggestions for electric vehicle charging station for the future.

Development of the stand for research electric vehicle’s traction system with supercapacitors

The authors have developed an EV traction system with microcontroller power management, based on feedback on the electric motor current consumption and SC charging rate control. The stand in a scale of 1:5 on the EV power system capacity was developed to evaluate the effectiveness of this system. The research results of electric vehicle (EV) acceleration mode using the combined power supplies, consisting of supercapacitors (SC) and storage battery (STB) were given in the paper.It was found that SC-based power supply provides the required peak power in the EV power supply system. At the same time, double increase in SC capacity does not give an adequate increase in discharge current. It is shown that the SC with low energy intensity is able to operate in the EV traction system with a small acceleration time.The proposed microcontroller management system of STB and SC operating modes in the EV traction system provides optimal and operational EM power management. The developed stand allows to increase charging run time.