Overview of Permanent-Magnet Brushless Drives for Electric and Hybrid Electric Vehicles

With ever-increasing concerns on our environment, there is a fast growing interest in electric vehicles (EVs) and hybrid EVs (HEVs) from automakers, governments, and customers. As electric drives are the core of both EVs and HEVs, it is a pressing need for researchers to develop advanced electric-drive systems. In this paper, an overview of permanent-magnet (PM) brushless (BL) drives for EVs and HEVs is presented, with emphasis on machine topologies, drive operations, and control strategies. Then, three major research directions of the PM BL drive systems are elaborated, namely, the magnetic-geared outer-rotor PM BL drive system, the PM BL integrated starter-generator system, and the PM BL electric variable-transmission system.     

Special Section on Vehicular Energy-Storage Systems

The ten papers in this special section focus on state-of-the-art research and development and future trends in the modeling, design, control, and optimization of energy-storage systems for electric vehicles (EVs), hybrid electric vehicles (HEVs), fuel cell vehicles, and plug-in HEVs.     

The state of the art of electric and hybrid vehicles

In a world where environment protection and energy conservation are growing concerns, the development of electric vehicles (EV) and hybrid electric vehicles (HEV) has taken on an accelerated pace. The dream of having commercially viable EVs and HEVs is becoming a reality. EVs and HEVs are gradually available in the market. This paper will provide an overview of the present status of electric and hybrid vehicles worldwide and their state of the art, with emphasis on the engineering philosophy and key technologies. The importance of the integration of technologies of automobile, electric motor drive, electronics, energy storage, and controls and also the importance of the integration of society strength from government, industry, research institutions, electric power utilities, and transportation authorities are addressed. The challenge of EV commercialization is discussed     

Investigation of the Energy Regeneration of Active Suspension System in Hybrid Electric Vehicles

This paper investigates the idea of the energy regeneration of active suspension (AS) system in hybrid electric vehicles (HEVs). For this purpose, extensive simulation and control methods are utilized to develop a simultaneous simulation in which both HEV powertrain and AS systems are simulated in a unified medium. In addition, a hybrid energy storage system (ESS) comprising electrochemical batteries and ultracapacitors (UCs) is proposed for this application. Simulation results reveal that the regeneration of the AS energy results in an improved fuel economy. Moreover, by using the hybrid ESS, AS load fluctuations are transferred from the batteries to the UCs, which, in turn, will improve the efficiency of the batteries and increase their life.      

Energy management strategies for vehicular electric power systems

In the near future, a significant increase in electric power consumption in vehicles is expected. To limit the associated increase in fuel consumption and exhaust emissions, smart strategies for the generation, storage/retrieval, distribution, and consumption of electric power will be used. Inspired by the research on energy management for hybrid electric vehicles (HEVs), this paper presents an extensive study on controlling the vehicular electric power system to reduce the fuel use and emissions, by generating and storing electrical energy only at the most suitable moments. For this purpose, both off-line optimization methods using knowledge of the driving pattern and on-line implementable ones are developed and tested in a simulation environment. Results show a reduction in fuel use of 2%, even without a prediction of the driving cycle being used. Simultaneously, even larger reductions of the emissions are obtained. The strategies can also be applied to a mild HEV with an integrated starter alternator (ISA), without modifications, or to other types of HEVs with slight changes in the formulation.     

The State of the Art of Electric, Hybrid, and Fuel Cell Vehicles

With the more stringent regulations on emissions and fuel economy, global warming, and constraints on energy resources, the electric, hybrid, and fuel cell vehicles have attracted more and more attention by automakers, governments, and customers. Research and development efforts have been focused on developing novel concepts, low-cost systems, and reliable hybrid electric powertrain. This paper reviews the state of the art of electric, hybrid, and fuel cell vehicles. The topologies for each category and the enabling technologies are discussed     

Power electronics intensive solutions for advanced electric, hybrid electric, and fuel cell vehicular power systems

There is a clear trend in the automotive industry to use more electrical systems in order to satisfy the ever-growing vehicular load demands. Thus, it is imperative that automotive electrical power systems will obviously undergo a drastic change in the next 10-20 years. Currently, the situation in the automotive industry is such that the demands for higher fuel economy and more electric power are driving advanced vehicular power system voltages to higher levels. For example, the projected increase in total power demand is estimated to be about three to four times that of the current value. This means that the total future power demand of a typical advanced vehicle could roughly reach a value as high as 10 kW. In order to satisfy this huge vehicular load, the approach is to integrate power electronics intensive solutions within advanced vehicular power systems. In view of this fact, this paper aims at reviewing the present situation as well as projected future research and development work of advanced vehicular electrical power systems including those of electric, hybrid electric, and fuel cell vehicles (EVs, HEVs, and FCVs). The paper will first introduce the proposed power system architectures for HEVs and FCVs and will then go on to exhaustively discuss the specific applications of dc/dc and dc/ac power electronic converters in advanced automotive power systems.     

Power-Electronics-Based Solutions for Plug-in Hybrid Electric Vehicle Energy Storage and Management Systems

Batteries, ultracapacitors (UCs), and fuel cells are widely being proposed for electric vehicles (EVs) and plug-in hybrid EVs (PHEVs) as an electric power source or an energy storage unit. In general, the design of an intelligent control strategy for coordinated power distribution is a critical issue for UC-supported PHEV power systems. Implementation of several control methods has been presented in the past, with the goal of improving battery life and overall vehicle efficiency. It is clear that the control objectives vary with respect to vehicle velocity, power demand, and state of charge of both the batteries and UCs. Hence, an optimal control strategy design is the most critical aspect of an all-electric/plug-in hybrid electric vehicle operational characteristic. Although much effort has been made to improve the life of PHEV energy storage systems (ESSs), including research on energy storage device chemistries, this paper, on the contrary, highlights the fact that the fundamental problem lies within the design of power-electronics-based energy-management converters and the development of smarter control algorithms. This paper initially discusses battery and UC characteristics and then goes on to provide a detailed comparison of various proposed control strategies and proposes the use of precise power electronic converter topologies. Finally, this paper summarizes the benefits of the various techniques and suggests the most viable solutions for on-board power management, more specific to PHEVs with multiple/hybrid ESSs.      

The great battery search [electric vehicles]

Batteries are the Achilles' heel of electric vehicles (EVs). Advocates of EVs frequently find themselves explaining why no electric car can drive far without refueling and as frequently promising things will get better any year now, as soon as the latest advance in batteries reaches maturity. As the search goes on for new electrochemical couples, designers try to avoid the pitfalls of the old ones. The article discusses the problems of batteries for EVs and discusses Li-ion, Ni-MH and Ni-Cd battery developments. The possibility of using primary batteries is briefly discussed as are battery charging technologies, safety and health issues     

Dynamic simulation for analysis of hybrid electric vehicle system and subsystem interactions, including power electronics

Simulation tools for hybrid electric vehicles (HEVs) can be classified into steady-state and dynamic models, according to their purpose. Tools with steady-state models are useful for system-level analysis. The information gained is helpful for assessing long-term behavior of the vehicle. Tools that utilize dynamic models give in-depth information about the short-term behavior of sublevel components. In this paper, a dynamic model of a hybrid electric vehicle that includes fuel cells, batteries, ultracapacitors, and induction machine drives is presented. Simulation results of vehicle configurations with a battery, a fuel cell-battery combination and a fuel cell-ultracapacitor combination are discussed. The focus of the model is a detailed assessment of different subsystem components, particularly component losses.     

Advanced Integrated Bidirectional AC/DC and DC/DC Converter for Plug-In Hybrid Electric Vehicles

Hybrid electric vehicle (HEV) technology provides an effective solution for achieving higher fuel economy, better performance, and lower emissions, compared with conventional vehicles. Plug-in HEVs (PHEVs) are HEVs with plug-in capabilities and provide a more all-electric range; hence, PHEVs improve fuel economy and reduce emissions even more. PHEVs have a battery pack of high energy density and can run solely on electric power for a given range. The battery pack can be recharged by a neighborhood outlet. In this paper, a novel integrated bidirectional AC/DC charger and DC/DC converter (henceforth, the integrated converter) for PHEVs and hybrid/plug-in-hybrid conversions is proposed. The integrated converter is able to function as an AC/DC battery charger and to transfer electrical energy between the battery pack and the high-voltage bus of the electric traction system. It is shown that the integrated converter has a reduced number of high-current inductors and current transducers and has provided fault-current tolerance in PHEV conversion.     

Modeling of Zinc Bromide Energy Storage for Vehicular Applications

Energy storage devices such as lithium-ion and nickel-metal hydrate batteries and ultracapacitors have been considered for utilization in plug-in hybrid electric vehicles (HEVs) and HEVs to improve efficiency and performance and reduce gas mileage. In this paper, we analyze and model an advanced energy storage device, namely, zinc bromide, for vehicular applications. This system has high energy and power density, high efficiency, and long life. A series of tests has been conducted on the storage to create an electrical model of the system. The modeling results show that the open-circuit voltage of the battery is a direct function of the battery's state of charge (SOC). In addition, the battery internal resistance is also a function of SOC at constant temperature. A Kalman filtering technique is also designed to adjust the estimated SOC according to battery current.      

Transportation [Technology 1998 analysis and forecast]

The safety debate has taken a new twist in both the aviation and the rail industries. High-profile aviation disasters and freight train wrecks have prompted demands for another great leap forward in safety. In both industries, new technology is playing a key role. And in the automotive field, public health will be the ultimate beneficiary if electric or hybrid electric vehicles start coming into wider use now that manufacturers have announced significant improvements in range. An enhanced ground proximity warning system for aviation, automatic train control, development of high speed trains, and electric vehicles powered by batteries and fuel cells, are discussed     

Metal fuel cells [Zn-air fuel cells]

The author describes a zinc-air fuel cell system which may be used for everything from electric vehicles (EVs) to backup generators, and may also provide practical and efficient energy storage     

Electric vehicles

The renewed interest in electric vehicles (EVs) in the wake of the California Air Resources Board mandate that 2% of the vehicles lighter than 3750 lb (1700 kg) sold by each manufacturer in that state in 1998 be zero-emission vehicles is examined. The reasons why replacing an internal combustion vehicle (ICV) with an electrically powered equivalent greatly reduces air pollution, not only where the EV is driven, but over the rest of the map as well are discussed. Three drawbacks that have kept EVs from taking over, despite the fact that they are quieter and more reliable as well as less polluting than their internal combustion counterparts, are discussed. They offer limited range on a simple charge, long recharge time, and higher cost than ICVs. The importance of an appropriate infrastructure is stressed     

Engineering the EV future

Continuing environmental concerns are moving electric vehicles (EV) into high gear at development facilities everywhere. The General Motors EV1 and the Ford Ranger EV are old news, the 106 Electric from PSA Peugeot-Citroen is established in France, where more than 1500 have been sold, and Toyota's Prius hybrid electric vehicle has exceeded all expectations in Japan, with plans afoot for an early introduction in the United States. In share-of-market terms, electric vehicles (EVs) are just beginning their infancy, total worldwide sales will be measured in the thousands of cars in 1998, compared with perhaps 20 million vehicles sold in all. But the big companies at long last are taking EVs seriously. The question now seems to be not whether automobiles will go electric but when. Battery, fuel cell and hybrid vehicles are briefly reviewed in this article     

Neue Fahrzeugtechnologien durch Brennstoffzelle und Elektroantrieb

Electric drive train systems are introduced to automotive application by hybrid vehicles as well as by new electric powered auxiliary units. As a preliminary step in the development of zero emission cars with hydrogen as energy carrier and fuel cells as energy converters they bring about new concepts such as high performance electric motors and sandwich chassis constructions. In combination with short term energy storage systems like super caps and new battery systems even more powerful zero-emission vehicles can be realized. Early applications of these technologies can be observed in transit busses and light duty vehicle fleets for field trials.     

Hybrids to the rescue [hybrid electric vehicles]

Whilst pure electric vehicles have floundered, hybrid electric vehicles (HEVs) have been making major gains and could soon make their mark. This article discusses the failings of pure electric vehicles and how HEVs get round the problems. The development and introduction of HEVs is briefly mentioned. The tax incentives for buying HEVs in Japan are discussed and the situation in the USA outlined.     

Hybrids: then and now

Very different from their turn-of-the-century forebears, modern hybrid electric vehicles (HEV) are almost as clean as pure EVs and have the range of conventional cars. The author discusses the advantages of HEV and describes the two basic types of HEV, parallel and serial. The serial type has a downsized engine on board that drives a generator that supplements the batteries and can charge them when they run low. In the parallel type the ICE and the electric motor can both deliver propulsion power to the wheels. The advantages of these two types of HEV are discussed. The parallel HEV is then discussed in more detail     

Advanced vehicle system concepts

Various nonpetroleum vehicle system concepts for passenger vehicles in the 1990's are being considered as part of the Advanced Vehicle (AV) Assessment at the Jet Propulsion Laboratory. The vehicle system and subsystem performance requirements, the projected characteristics of mature subsystem candidates, and promising systems are presented. The system candidates include electric and hybrid vehicles powered by electricity with or without a nonpetroleum power source. The subsystem candidates include batteries (aqueous-mobile, flow, high-temperature, and metal-air), fuel cells (phosphoric acid, advanced acids, and solid polymer electrolyte), nonpetroleum heat engines, advanced dc and ac propulsion components, power-peaking devices, and transmissions.