하이브리드 및 전기 자동차용 LDC 재생형 부하 시험기 설계

This paper confirms the operational limit and breakdown threshold of low voltage dc-dc converters (LDCs), which are a key component of electric vehicles (xEVs) systems, proposes a highly accelerated life test (HALT) method for predicting the operational lifetime of LDC, and analyzes the experimental results. HALT is the most effective test process for predicting the operational limit and breakdown threshold of products. Especially, for vehicle component HALT, the operational environment and product characteristics must be understood and the test method should be designed. Although LDC is a brand new key component for xEVs, designing the rational test process remains difficult since there are only a few research cases. In this paper, HALT has been implemented to take account of the electrical performance and operational characteristics under the real development process of an LDC. The prototypes are 1.5 kW class LDCs which are applied to the HEV in mass production, and the test has been carried out considering the condition of real vehicle installation and operational conditions. Through the test results, the upper operating limit (UOL) and lower operating limit (LOL) are identified, and the electrical mechanism which generates the operational limit is analyzed.

Our way of life is on a collision course with geological limitations. Ever since petroleum geologist M. King Hubbard correctly predicted in l956 that U.S. oil production would reach a peak in l973 and then decline (1), scientists and engineers have known that worldwide oil production would follow a similar trend. Today, the only question is when the world peak will occur.The U.S. transportation system depends almost entirely (∼97%) on oil (2), and foreign imports have risen steadily since l973 as the demand increased and domestic supplies decreased. Today, more than 60% of U.S. oil consumption is imported and the dependence on foreign oil is bound to increase. There is no question that once the world peak is reached and oil production begins to drop, either alternative fuels will have to be supplied to make up the difference between demand and supply, or the cost of fuel will increase precipitously and create an unprecedented social and economic crisis for our entire transportation system.Among energy analysts the above scenario is not in dispute. There is, however, uncertainty about the timing. Bartlett (3) has developed a predictive model based on a Gaussian curve similar in shape to the data used by Hubbard as shown in Fig. 1. The predictive peak in world oil production depends only on the assumed total amount of recoverable reserves. According to a recent analysis by the Energy Information Agency (4), world ultimately recoverable oil reserves are between 2.2×1012 barrels (bbl) and 3.9×1012bbl with a mean estimate of the USGS at 3×1012bbl. But changing the total available reserve from 3×1012bbl to 4×1012bbl increases the predicted time of peak production by merely 11yr, from 2019 to 2030. The present trend of yearly increases in oil consumption, especially in China and India, shortens the window of opportunity for a managed transition to alternative fuels even further. Hence, irrespective of the actual amount of oil remaining in the ground, peak production will occur soon and the need for starting to supplement oil as the primary transportation fuel is urgent because an orderly transition to develop petroleum substitutes will take time and careful planning.Some analysts claim that hydrogen can take the place of petroleum in a future transportation system (56). But in previous publications, the authors have shown that hydrogen is inferior as an energy carrier to electricity (7) and that the energy efficiency of hydrogen vehicles, especially if the hydrogen were produced by the electrolysis of water, is considerably less than the efficiency of hybrid electric vehicles or fully electric battery vehicles (7). The results of these analyses have subsequently been confirmed by other studies, particularly those by Hammererschlag and Mazza (8) and Mazza and Hammerschlag (9).Before hydrogen could become a useful automotive fuel, an entirely new system of energy production and distribution on twice the scale of today’s electric power generating stations and distribution grid would have to be built. It has been estimated that a hydrogen transmission and storage system to fuel only 50% of the automotive fleet by the year 2020 would cost at least $600 billion (10) and that to make the hydrogen by electrolysis would require doubling the electric power generation rate (11). There is no question that a paradigm shift in fuel for worldwide transportation is imperative, and before embarking on such a huge investment, it is prudent to compare the hydrogen option with alternative ways to provide the energy and/or fuel needed by the transportation system.This paper presents and analyzes two generic approaches to meet the future demand of the U.S. ground transportation systems that do not require hydrogen, can use existing transmission infrastructure, and can eventually reduce CO2 emission drastically with a renewable energy system. Both these pathways are examined from an energetic and environmental perspective and are shown to be superior to the hydrogen economy on both these criteria. The first approach is a demand-side strategy based on the use of electric hybrid vehicles, an energy-efficient vehicle configuration, combined with a liquid fuel. This approach could use the existing liquid-fuel distribution system, but would need an expanded and robust electric-transmission system, albeit on a smaller and much more economical scale than a hydrogen fuel-cell infrastructure. The second approach is a supply-side strategy, based on synthetic fuel generation that can use initially coal or natural gas as the energy source, but can eventually transition to renewable biomass sources. The two pathways are not mutually exclusive, but can be combined into a secure and efficient future transportation system as will be shown in this paper.Cradle-to-grave energy efficiency is an important criterion for comparing energy-source utilization pathways because if a pathway is less efficient than another pathway that accomplishes the same final goal from the same amount of primary energy, then the less efficient pathway requires more primary energy to accomplish the same end. Hence, if the primary energy source is nonrenewable, then the less efficient pathway leaves less of the energy source for the future. It also means that more pollution is produced and the cost for the final end use is likely higher. However, if the primary energy source is renewable, then the efficiency does not change the amount of primary energy available in the future and energy efficiency does not have the same significance for renewable energy sources as for nonrenewable sources. Efficiency is, of course, important because the cost of delivering the energy is usually strongly influenced by the system efficiency. But a comparison between renewable and nonrenewable pathways should be based on economic and environmental criteria, such as cost and CO2 generation.In order to demonstrate the urgency for initiating a plan to supplement oil as soon as possible, we have made calculations to predict the potential gasoline savings based on the very optimistic scenario that, at an arbitrary starting time, all new light vehicles sold in the U.S. would be either hybrid or electric vehicles. The term “light vehicles” as used here includes all automobiles, family vans, sports utility vehicles, motorcycles, and pickup trucks. This scenario is an extreme case to show that because of the slow turnover of the light-vehicle fleet, it takes a long time for a significant impact on gasoline consumption to occur. The following cases are considered: (i) All new vehicles sold are gasoline-electric hybrid vehicles (HEV); (ii) all new vehicles sold are plug-in, gasoline-electric hybrids with a 20mil electric-only range (PHEV20); (iii) all new vehicles are diesel-electric hybrids (DHEV) with diesel fuel from coal or biomass; (iv) all new vehicles are plug-in, diesel hybrids with a 20mil all-electric range (PDHEV20); or (v) all new vehicles are all-electric vehicles (EV).The calculations use a rate of new vehicle sales of 7% of the fleet per year, a retirement rate of 5%/y, and a resulting net increase in total vehicles of 2%/y. These numbers represent an approximate fit to the light-vehicle sales and total number data for the years 1966 to 2003 reported by the U.S. government (12). All calculated results are presented in percentages and are therefore independent of the time at which all new vehicle sales switch to hybrids or EVs. When new car sales begin to be all hybrids or all EVs, it is assumed that the future rate of retirement of vehicles from the all-gasoline fleet is 5%/y of the remaining gasoline vehicles. The all-gasoline fleet is therefore completely retired 20 years later. The yearly rate of retirement of hybrid or EV vehicles is then 5% of the total number of vehicles at the beginning of that year, less 5% of the number of gasoline vehicles at the beginning of year zero. Thus, in year zero, no hybrid or EVs are retired.The following average vehicle mileage values were used: gasoline fleet, 21mpg (miles per gallon); gasoline HEV, 41mpg; gasoline PHEV 20, 56mpg of gasoline (13). A mileage is not needed for the EVs, or the diesels, since neither use gasoline, and we assume that the diesel fuel will be derived from nonpetroleum sources, as discussed in Secs. 34.The results of these calculations are presented in Figs. 234. Figure 2 shows the ratio of the total number of vehicles in the fleet, the number of all-gasoline vehicles in the fleet, and the number of hybrid or EV vehicles in the fleet to the total number in the fleet as a function of time. The total number of vehicles increases by over 60% in 25 years at the assumed 2%/y net increase while the number of all-gasoline vehicles decreases linearly from 100% initially to 0% after 20y. The number of hybrid or EV vehicles increases from 0% initially to 58% in 10y and 100% in 20y. This graph emphasizes how long it takes for the introduction of a new vehicle type to show a significant impact on the composition of the vehicle fleet, even when only the new vehicle types are sold after a starting point. This slow turnover of the fleet is the fundamental reason that the effects on gasoline consumption show up so slowly.Figure 3 shows the annual reduction in gasoline consumption as a function of time. Note that for HEVs the annual savings in gas consumption is 29% of the gasoline consumption for a conventional fleet in the tenth year and becomes constant at 49% in the twentieth year. Figure 3 also shows that the plug-in gasoline hybrid scenario saves 41% of the usage in the tenth year and increasing to 64% in the twentieth year and thereafter. Clearly, 10y after starting to sell only hybrid or EV vehicles, the impact of the HEV or PHEV20 scenarios on gasoline consumption is still rather small. After 20yr, the impact becomes significant, but gasoline consumption still remains high for gasoline hybrids. The total number of vehicles and the consumption (with the assumption of no efficiency improvement) by an all-gasoline fleet will have increased by more than 60%, but even the PHEV20 savings is only 40% of the zero-time annual-rate of gasoline consumption. The DHEV, DPHEV20, and EV scenarios show 59% annual savings in the tenth year and 100% in the twentieth year and thereafter. As would be expected, the nongasoline vehicles have a much greater impact on gasoline usage than gasoline-using HEVs, and the impact occurs more rapidly.Figure 4 gives the cumulative gasoline savings for the various scenarios compared to an all-gasoline fleet. HEVs save cumulatively 16% after 10yr and 20% after 20 years. Because of the cumulative savings, HEVs would use in 28yr the same amount of gasoline as an all-gasoline fleet would use in 20yr. PHEV20s save 21% after 10yr and 38% after 20yr. These results emphasize the relatively small effect on gasoline consumption that these highly optimistic scenarios have in the first decade after implementation. DHEVs, DPHEV20s, and EVs, the options without any gasoline use, save cumulatively as much as 32% after 10yr and 59% after 20yr.A 2004 report of the Committee on Alternatives and Strategies for Future Hydrogen Production and Use (14), prepared under the auspices of the National Research Council (NRC), concluded that the vision of a hydrogen economy is based on the expectation that hydrogen can be produced from domestic energy sources in a manner that is “both affordable and environmentally benign.” An analysis of currently available technologies for achieving this goal (7) showed that irrespective of whether fossil fuels, nuclear fuels or renewable technologies are used as the primary energy source, hydrogen is inefficient compared to using the electric power or heat from any of these sources directly. Given these facts, it is important to note that the NRC report also stated that “If battery technology improves dramatically, all-electric vehicles might become the preferred alternative (to fuel cell electric vehicles).” The report also noted that “Hybrid vehicle technology is commercially available today and can therefore be realized immediately.” If synthetic fuels made from coal, natural gas, or biomass were used in place of gasoline in hybrid vehicles, the consumption of oil could be reduced immediately and eventually eliminated. In the light of these observations, it is therefore important to examine what the current state of battery technology is, what can be expected in the near future, and how these developments affect the potential of hybrid vehicle performance and economics.To assess the performance of a battery for electric vehicles, the following characteristics have to be considered: Specific energy, a measure of the battery weight in units of watt hours per kilogramEnergy density, a measure of the space the battery occupies in watt hours per cubic meterCapacity, the total quantity of energy a battery can store and later deliver in watt hoursEfficiency, the ratio of energy that can be extracted from the battery to the initial energy input to change the batterySpecific power, the rate at which the battery can deliver the stored energy per unit weight of battery in watts per kilogramBattery lifecycle, the number of charge and discharge cycles that a battery can sustain during its lifeA significant effort to replace oil as a transportation fuel was undertaken ten years ago in California, when the California Air Resources Board [CARB] mandated that a certain percentage of all vehicles sold in California had to have zero tailpipe emissions (15). At that time the only technology available to meet the mandate was the all battery electric vehicle [BEV], which required no gasoline for its operation. The experiment to mandate the use of BEVs in California failed because the technology was not ready for commercialization. The best battery available in 1995 (fluted-tubular lead acid) had an energy storage density of 35Wh∕kg, a specific power of 100W∕kg, and a life cycle of 600-1000cycles. With these battery characteristics, the maximum range of a BEV was only 50mil, and the battery pack required replacement every 25,000mil at a cost of between $7000 and $8000 for an average BEV (16). Since that time, new batteries have been developed by Panasonic, VARTA, and SAFT, that have twice the energy-storage density, three times the specific power, and two or three times the cycle life of the lead acid batteries sold in California, as shown in Table 1 (13).In addition to the advanced batteries, a new concept has been developed that combines the best qualities of hybrid and battery vehicle technologies. This “plug-in hybrid vehicle” can recharge vehicle batteries during off-peak hours, and since most cars are parked 90% of the time, there are plenty of charging opportunities at both home and the workplace. Furthermore, a large portion of the electric generation infrastructure is only needed for peak demands and lays idle much of the time. Hence, if charging automobile batteries occurred during off-peak hours, they would level out the load of the electric production system and reduce the average cost of electricity (17). Moreover, plug-in hybrid vehicles are not range limited because they have an engine that can refuel at existing gas stations to use when the batteries are low.The efficiency of a PHEV depends on the number of miles the vehicle travels on liquid fuel and electricity, respectively, as well as on the efficiency of the prime movers according to1η=energytowheelsenergyfromprimarysource=f1η1η2+f2η3η4where η1 is the efficiency of the primary source of electricity, η2 is the efficiency of transmitting electricity to the wheels, f1 is the fraction of energy supplied by electricity, f2 is the fraction of energy supplied by fuel =(1−f1), η3 is the efficiency of primary source to fuel, and η4 is the efficiency of fuel to wheels.PHEVs can be designed with different all-electric ranges. The distance, in miles, that a PHEV can travel on batteries alone is denoted by a number after PHEV. Thus, a PHEV20 can travel 20mil on fully charged batteries without using the gasoline engine. According to a study by EPRI (13), on average 1/3 of the annual mileage of a PHEV20 is supplied by electricity and 2/3 by gasoline. The percentage depends, of course, on the vehicle design and the capacity of the batteries on the vehicle. A PHEV60 can travel 60mil on batteries alone, and the percentage of electric miles will be greater as will the battery capacity.The tank-to-wheel (more appropriately, battery-to-wheel) efficiency for a battery all-electric vehicle according to EPRI (13) is 0.82. In a previous analysis by the authors (18), the efficiency in 1993 was only 0.49. Comparing these results shows the enormous improvements in the electric component efficiency (controller 87%, battery 90%, charger 90%, drivetrain 90%;). When these numbers are multiplied by a hybrid-weight-times-idle factor of 1.3 (19), the overall efficiency of an electric hybrid is 82%, the same as that used in the EPRI study (13). It is important to note that currently all-electric vehicles can be nearly twice as efficient as when (18) was published.Given the potentials for plug-in hybrid vehicles, the Electric Power Research Institute (13) conducted a large-scale analysis of the cost, the battery requirements, and the economic competitiveness of plug in vehicles today and within the near term future. Table 2 presents the net present value of life-cycle costs over ten years for a midsized combustion vehicle [CV], hybrid vehicle [HEV] and a plug in electric vehicle with a 20mil electric-only range [PHEV20]. The battery module cost in dollars per kilowatt is the cost at which the total life-cycle costs of all three vehicles would be the Figure presents cost for battery as a function of number of units produced per year. According to this a production of about units per year units would the cost reduction to make both hybrid electric vehicles and plug in electric vehicles 3 presents the electric and plug-in hybrid vehicle battery that would be to make electric vehicles cost for vehicles according to EPRI (13). As shown in Table the characteristics of batteries, and batteries are to meet the required cost and performance The battery characteristics shown in Table 1 and Fig. are years and it is likely that more from would show Furthermore, the EPRI study assumed a current gasoline cost of A of the analysis based on a gasoline cost of that the battery at which the net present values of conventional combustion vehicles and battery vehicles are would up from to for an HEV and from to for a PHEV Figure shows the cost for batteries production for Hence, it that the cost of HEVs and with available batteries is with that of engine The EPRI analysis is because it compared the performance of all battery electric and plug in hybrid vehicles only to currently available combustion as shown in the use of diesel in a hybrid would increase the efficiency of compared to a hybrid with engine and the amount of fuel Hence, it be concluded that the EPRI analysis is it includes advanced batteries, it does not the increased efficiency by using diesel of combustion Furthermore, diesel fuel, as will be shown in can be produced from coal or renewable sources as can the electric power required for charging the The introduction of to the energy is the of this it is and can be as renewable technologies become more cost and fossil fuels more natural gas and biomass can be into liquid the most fossil fuel in the is used almost to In order to make coal into a vehicle fuel, it first be to a gas by a of The of this then be to of that can be used as vehicle fuel. biomass and natural gas can be used of coal or combined with coal to make these and are discussed gas can be used as a vehicle fuel, or it can be with to make gas, which can be used to fuels in the same manner as for The technology is well developed as shown by the recent of of which will natural gas, which is currently to liquid fuel. These and a in of which is diesel in With a with an estimated billion and a diesel with the of with an estimated at The of natural gas to make vehicle fuels was discussed in an paper by the authors (18), and of those results are presented later for comparison with coal as the fuel It should also be noted that biomass can be either alone or in with coal and to liquid fuels by the same as coal, or it can also be and then into vehicle fuels as in is a that is a in the production of synthetic liquid fuels from coal for transportation The coal is shown in Fig. It a such as coal or with to and This gas can be to hydrogen or to make or can be used as a transportation fuel in but this study on diesel fuel because are more the first of the coal is with limited to and The in the coal is to hydrogen gas, and are as In the shift is with to and The and hydrogen are from the and to the or into The that is in this is from the in a for Thus, it can be from the and are the costs when liquid fuel is produced from The estimated time of for a is to years. The depends on the production capacity of the the cost of a with a capacity to barrels of liquid fuel per is estimated to be of the order billion of coal claim that there will be gas pollution from the However, in the future vehicle emissions of can be reduced those of vehicles, by the use of plug-in hybrid electric vehicles and by of the from the fuel production is a synthetic diesel fuel that can be made from coal by of The is first to make which can then be to The is to the and the gas is to electricity for the as shown in Fig. is a gas at but can be under and then can be to other liquid of make it an fuel for It is similar to but has a number The number to the of a fuel to With combustion of the fuel occurs after and emissions are as a of combustion The combustion also in by the need for to the shown in Fig. coal into liquid fuel. The was by scientists before and is used today in by to make diesel fuel gas to make a liquid fuel of synthetic diesel fuel, which is similar to and which is used to make synthetic gasoline (7). The is from the liquid diesel and to the The gas resulting from is to electricity for the can be made from coal by by gas After the hydrogen gas and are from the gas, and hydrogen are The hydrogen can be stored and the can be for electricity and/or to the shift as shown in Fig. store and the hydrogen, it is either to it to or to it at a The efficiency of the first option is while the second is efficient (7). Both and hydrogen have been for fuel storage in a of hydrogen fuel-cell vehicles is in the of coal or natural gas into a vehicle fuel. The energy efficiency of these is important in the overall well to efficiency of these alternative Table 4 presents or efficiency for various fuels from coal or natural and have reported the and energy for with of the and values are used (18) presented for natural gas without and estimated that of CO2 the efficiency of by about two percentage Since natural gas only about as much per unit of energy as coal, it has been assumed that will reduce the efficiency of to fuels by percentage point. Thus, percentage has been from values reported by (18) to the values shown in Table In the of data for the of natural gas to the authors assumed that the ratio of the for natural gas is the same as that for coal to estimate this efficiency as shown in Table 4 that the production of liquid fuels from natural gas is more efficient than from But is in and the technology is not a It is however, for the that is currently into the in gasoline The of of these has been But production is the more for the term and does not require hydrogen as a fuel or energy Today, the of fuel from coal, at the only in The of supplies of such fuels as gasoline, and The economic and of coal have been U.S. and for a fuel in using technology and are to the that will have a capacity to of diesel fuel. has in recent NRC study other technologies that could synthetic fuels from biomass and presents a comparison of the energy on energy for production from and These significant in synthetic But the for synthetic fuel production need to be multiplied before synthetic fuels can make up for the between demand and of gasoline after the peak in oil production is on the analysis presented in this we the following and oil production is expected to peak within the and as is liquid fuel are expected to increase This could lead to a crisis in the U.S. transportation system that on 60% of which is options for a transportation crisis by and/or liquid fuels derived from petroleum with synthetic fuels from natural gas, or coal and by demand by increasing the efficiency and mileage of options to have impact they be at least before hybrid vehicles are a option to reduce the liquid fuel consumption of future transportation hybrid vehicles can the existing infrastructure for electric power transmission by charging batteries during peak hours and use liquid fuels only for a fraction of overall power hybrid vehicles can diesel that can be by synthetic fuels derived from coal, natural gas, or use efficiency is increased efficiency alone will not be to the transportation without the production of large of synthetic liquid number of technologies for synthetic diesel that can be used in diesel and reduce emission of that lead to scale of effort required to provide synthetic fuels will require years to and should therefore be as soon as hybrid or all-electric vehicles with available battery technology in an are compared to gasoline of the of the transportation it is that be by government such as for the of synthetic fuels and CO2 high liquid fuel mileage for automobiles, and for efficient plug-in hybrid scenario in this paper for a secure transportation system can be immediately with available technologies and without hydrogen or authors to for as of an independent study for the of at the of

This paper proposes a new active balancing method adding an auxiliary circuit to a LDC (Low voltage dc/dc Converter) circuit to increase battery utilization ratio. The proposed system incorporates a distributed structure for HVBAT (High Voltage Battery) modules with individually mounted LDC. On/off switching and discharge current are controlled to balance the HVBAT modules. The system employs an active clamp forward converter to achieve soft switching, providing high efficiency. The proposed active balancing control with additional auxiliary circuit was verified through simulations and Experiments.

Integrated on-board charger (OBC) and low-voltage DC-DC converter (LDC) system is attractive for electric vehicles (EVs) due to its reduced number of switching devices and magnetic components. This paper proposes a novel high-density integrated magnetic component (IMC) that achieves the integration of the high-frequency transformers of the OBC and the LDC with the resonant inductor of the OBC, which reduces the cost, the weight, and the volume of the charging system. Based on the proposed IMC, the system can simultaneously charge the high-voltage battery (HVB) and the low-voltage battery (LVB). Moreover, an elliptical ring-shaped magnetic shunt is employed to achieve controllable leakage inductance, and Litz wire is adopted to replace the conventional busbar winding of the LDC to reduce eddy-current losses and support high-current output. Detailed analysis and design guideline of the proposed IMC are provided. To validate the feasibility of the proposed IMC, a prototype with an integrated 6.6 kW OBC and 2 kW LDC is built. The experimental results show that the proposed IMC achieves a power density of 660 W/in3 and enables the prototype to achieve a peak efficiency of 98.17

The on-board low-voltage dc-dc converter (LDC) in electric vehicles (EVs) is used to connect the high-voltage battery with the low-voltage auxiliary system. With the advancement of auxiliary equipment in EVs, the output current of the LDC can be hundreds of amperes, which will cause high-conduction loss and severe thermal concern. In this article, a high-efficiency high-power-density on-board LDC is presented. To reduce current stress and improve efficiency, three-phase interleaved LLC dc-dc converters are paralleled to provide 270 A load current. Synchronous rectifier is used to reduce secondary conduction loss. zero-voltage-switching (ZVS) turn-on of primary switches and ZCS turn-off of secondary switches are achieved, thus switching loss can be reduced significantly. Moreover, phase-shedding technology is used to improve light load efficiency. Switch-controlled capacitor (SCC) technology is used to achieve accurate load current sharing among the three phases, which protects the devices against high-current stress, reduces the conduction loss, and improves the reliability of the system. As SCC switches achieve ZVS turn-on and turn-off by its nature, the loss of the SCC circuit is of less concern with regard to the rated output power. In addition, GaN HEMTs are used in the primary side to improve the power density and eventually help achieving light weight. A 3.8-kW (14 V/270 A) LDC prototype is developed and tested. Experimental results show good current balancing among the three phases. A peak efficiency of 96.7% at 140 A load and a full load efficiency of 95.8% are achieved with 3 kW/L power density and 1.5 kg weight.

As the number of electric and hybrid vehicle users increases, there is growing interest in the topic of maintenance and servicing costs. Many literature sources do not provide information on this topic and only limit themselves to energy costs. However, it is not just energy costs that make up the total cost of owning such a vehicle. What is missing is an analysis of the difference between the cost of maintenance and operation of electric vehicles and that of internal combustion engine vehicles. This paper presents a results of research regarding the repair and servicing costs of electric and hybrid vehicles compared to combustion vehicles. A survey was carried out which shows that the repair costs of electric and hybrid vehicles are more than 20% higher. Repair and servicing of electric and hybrid vehicles should also take into account the repair time (depending on the availability of parts and the repair schedule of the repair shop in question) and the availability of personnel with the appropriate competence for such a repair. The five most frequently replaced items in internal combustion vehicles were: braking system, suspension system, oils and operating fluids and air conditioning. The five most frequently replaced items in hybrid and electric vehicles are: battery replacement or reconditioning, coolant replacement, suspension system, oils and operating fluids, electronics in general and braking system.

The problem of electromagnetic radiation of vehicles exists and worries people, because it is not clear what is the safe level of frequency, intensity, time spent by drivers and passengers in vehicles, etc. The article is devoted to the disclosure of the problems of adverse effects of electromagnetic fields (EMF) and electromagnetic radiation (EMR) of modern hybrid and electric vehicles on drivers, passengers, pedestrians and the environment. The purpose of the study was to investigate the process of occurrence, propagation and impact of negative functions of electromagnetic radiation on biological objects, their propagation speed, flicker, wavelength and frequency, and radiation devices in electric and hybrid vehicles. The methodology of the article is based on the results of research by scientists from around the world and our own research and experiments, the results of which are presented in this article. The results of the scientific work are reviewed from researchers on this topic and their own tests are described The authors point out the need to measure electromagnetic radiation at the stages of their operation, repair and manufacture, since these vehicles running on electric traction generate magnetic fields that can violate electromagnetic safety. This is because electric vehicles have power plants, sensors, control, information and communication systems. Electric currents flowing through electric motors, power circuits, and batteries while driving generate magnetic fields (MFs) in the low frequency ranges (ultra low frequency (ULF), 0.001 - 10 Hz; extremely low frequency (ELF), 10 - 300 Hz).Higher harmonics of the electric field in electric vehicles and hybrid vehicles are generated by various electronic devices on board, information and communication systems. For example, in hybrid vehicles, magnetic pulses of up to 5 kHz are generated when the internal combustion engine is switched to electric mode. In addition, all types of cars generate a low-frequency pulsating magnetic field when the steel wheel disks rotate. The frequency f of this field is determined by the wheel speed and is usually f 20 Hz, but the spectrum also contains harmonics. The scientific novelty is that for the first time the concept of modeling and optimization of electromagnetic hazard assessment of electric vehicles and hybrid vehicles is presented, which has a unified approach to the study of the magnetic field regardless of the structure and design schemes of their power plants at the stage of operation; for the first time methods for assessing important parameters of the magnetic field of electric vehicles and hybrid vehicles at the stage of operation are developed based on the concept of optimal control of the power plant depending on the operating conditions. The practical significance is the originality, which lies in the fact that the authors have considered the problems of determining the moment of occurrence of traffic hazards in various road and transport situations and the technical hazards of various types of electric vehicles and hybrid vehicles.

<div class="section abstract"><div class="htmlview paragraph">Hybrid and electric vehicles present a promising trade-off between the necessary reductions in emissions and fuel consumption, the improvement in driving pleasure and performance of today's and tomorrow's vehicles. These hybrid vehicles rely primarily on electronics for the control and the coordination of the different sub-systems or components. The number and complexity of the functions distributed over many control units is increasing in these vehicles. Functional safety, defined as absence of unacceptable risk due to the hazards caused by mal-function in the electric or electronic systems is becoming a key factor in the development of modern vehicles such as electric and hybrid vehicles. This important increase in functional safety-related issues has raised the need for the automotive industry to develop its own functional safety standard, ISO 26262.</div><div class="htmlview paragraph">The aim of the paper is to briefly introduce the ISO 26262 standard and the specific hazards associated with hybrid and electric vehicles. The paper will highlight how the risk-based approach of ISO 26262 can influence the safety integrity level of some safety related functions specific to hybrid and electric vehicles. It will also highlight how well established safety related functions, such as torque monitoring of a conventional internal combustion engine can be influenced through vehicle hybridization. A vehicle safety concept for the torque monitoring of an electric vehicle will then be presented. The results of the implementation of this functional safety concept in an electric vehicle developed by the company FEV GmbH will be shown as example. The first measurements made in the vehicle show that the monitoring concept fulfills the reaction time requirement to ensure that unintended torque increase do not lead to uncontrollable vehicle acceleration.</div></div>

The objective of this paper is to help state agencies better understand the impact of electric and hybrid vehicles on the Highway Trust Fund and to develop a method for estimating proper annual registration fees for electric vehicles (EVs). In this study, a comprehensive literature review was conducted to summarize the background on electric and hybrid vehicles, current national and state policies and incentives, the trend of EV market in the U.S., and registration fees on electric and hybrid vehicles. As electric and hybrid vehicles do not contribute to fuel excise tax revenue, to compensate the lost tax revenues, some states charge additional annual registration fees to EV owners. To help the legislators determine the proper annual fees, a method was developed to assess the additional registration fees for EVs and plug-in hybrid electric vehicles (PHEVs) in Alabama. The collected data include number of registered electric and hybrid vehicles, fuel tax per gallon, and annual average mileage traveled by electric and hybrid vehicles in Alabama. The results of this study served as a key reference in the Rebuild Alabama Act that proposed an annual registration fee of $200 and $100 for EVs and PHEVs, respectively, which is effective since January 2020. The method in this study can be applied to other states for developing policies on registration fees for EVs and PHEVs to offset the fuel excise tax revenue loss.

The depletion of fossil fuels, coupled with their ever-increasing prices and pollution, has presented humanity with the need to employ other energy sources to power our automobiles. Additionally, there seem to be problems concerning energy storage as well. Owing to the above reasons, electric, hybrid, and fuel-cell vehicles have garnered a ton of attention from vehicle manufacturers. Manufacturers like Tesla have already taken giant strides in manufacturing electric cars and trucks that are consumer-friendly. This review paper provides an overview of the various types of electric vehicles currently being researched upon, namely All-Electric Vehicles (AEVs) or Battery Electric Vehicles (BEVs), Plug-in Hybrid Electric Vehicles (PHEVs), Hybrid Electric Vehicles (HEVs) and Fuel Cell Electric Vehicles (FCEVs), the downsides to using electric vehicles and what the future holds in store with regards to the development of electric vehicle technology.

Data are presented that were obtained from the electric and hybrid vehicles tested, information collected from users of electric vehicles, and data and information on electric and hybrid vehicles obtained on a worldwide basis from manufacturers and available literature. The data and information thus obtained were evaluated and compiled to present the state-of-the-art of electric and hybrid vehicles. The data given include: (1) information and data base (electric and hybrid vehicle systems descriptions, sources of vehicle data and information, and sources of component data); (2) electric vehicles (theoretical background, electric vehicle track tests, user experience, literature data, and summary of electric vehicle status); (3) electric vehicle components (tires, differentials, transmissions, traction motors, controllers, batteries, battery chargers, and component summary); and (4) hybrid vehicles (types of hybrid vehicles, operating modes, hybrid vehicle components, and hybrid vehicle performance characteristics).

This paper presents methods and results which allow an analysis of relevant driving parameters of hybrid and electric vehicles. In order to gain crucial insights into how industrial customers use hybrid and electric vehicles, the paper investigates the following parameters: information about odometer, charging processes and battery charging levels. The data used for this purpose was provided by the Canadian fleet management company Geotab Inc. They were evaluated by means of ‘Google BigQuery’ and the statistics programme ‘IBM SPSS Statistics’. It turned out that correlations between ‘charging time’ and ‘battery charging level’ exist, as well as between ‘battery level’ and ‘distance per day’. One of the main questions in the present study asks whether long charging times of car batteries lead to decreased average battery charging levels. As a result of this study, the longer a hybrid vehicle is charged per day, the lower sink its average battery charging level. The findings of this research help managers of car fleets to enhance their existing fleet management for establishing more efficient fleets with respect to ecological and economical aspects. Our research is particularly significant as this will save money across such fleets worldwide, and at the same time, preserve the environment as much as possible. Keywords: fleet management, electric and hybrid vehicles, big data, battery charging DOI : 10.7176/ISDE/10-3-03 Publication date :March 31 st 2019

In this paper, a novel integrated transformer with adjustable leakage inductance is proposed to achieve high power density in electric-vehicle battery charger applications. By using a multi-winding transformer, the topological integration of on-boar charger (OBC) and low-voltage dc-dc converter (LDC) can be achieved, which effectively reduces the number of semiconductor devices, transformers, and ZVS inductors in the battery charger system (BCS). Additionally, the BCS enables simultaneous charging of low-voltage batteries and high-voltage batteries. Furthermore, the multi-winding transformer model is analyzed, and 3-D finite element analysis (FEA) is employed to evaluate the leakage inductances. To confirm the validity of the proposed transformer, a prototype with 6.6kW OBC and 2kW LDC is built. Experimental results demonstrate an average efficiency of 94.8% over the full voltage range of the high-voltage battery.

In the past few years, industry has been paying more attention on the size, efficiency and reliability of the power converters in portable electronic equipment. Highly-efficient low-voltage low-power switch-mode DC-DC converters are mandatory in these devices to regulate the supply voltage for maximizing the run-time of the systems. According to the semiconductor roadmap from Semiconductor Industry Association, the supply voltages of digital circuits have to be reduced to 0.9-l.2V by the year 2005. Moreover, the current-mode control is well-known to have faster response than the voltage-mode control, but requires more advanced circuit structures and is difficult to implement in low supply voltages. The design of low-voltage current-mode switch-mode DC-DC converters, therefore, becomes a very challenging and important research. This thesis is aimed to develop novel circuit structures for monolithic highly-efficient low-voltage current-mode DC-DC converters targeted for battery-operated handheld devices. Five novel circuitries have been proposed and implemented, including two low-voltage current-sensing circuits for PMOS and NMOS switches, a low-voltage voltage-controlled oscillator, a voltage-to-current generator, as well as a startup circuitry for boost converter. In addition, the detailed studies of the current-mode switch-mode DC-DC converter and the low-voltage circuit designs of the required building blocks are included in this thesis. The proposed current-mode buck and boost converters have been implemented in AMS 0.6-μm CMOS technology with V<sub>thn</sub>≈│V<sub>thp</sub>│≈0.85V at room temperature. The proposed buck converter is able to operate at 1.2-V supply with more than 89.6% conversion efficiency and a maximum output current of 125mA, while the proposed boost converter is able to operate at 1-V supply with more than 85% conversion efficiency and a maximum output current of 150mA. The accuracy of the proposed current-sensing circuitry is higher than 93%.

In lithium-ion battery systems for electric vehicles (EVs), the high voltage battery is composed of several modules, and a balance between them is essential to improve battery life and safety. In this paper, a novel low-voltage DC/DC converter (LDC) with integrated inter-module battery equalization circuit (IBEC) is proposed. The proposed converter can be implemented by adding a small number of elements to the existing phase shift full bridge (PSFB) DC/DC Converter, which is widely used as an LDC, and can effectively balance the target module in both directions of charging and discharging. IBEC switches are capable of ZVS operation over the entire load range, while PSFB converter switches can achieve ZVS without additional inductors, especially in discharge mode. To verify the balancing and powering operations, a prototype of 1kW is implemented and experimented.