This paper deals with the problem of controlling a hybrid energy storage system (HESS) for electric vehicles. The storage system consists of a fuel cell (FC), serving as the main power source, and a supercapacitor (SC), serving as an auxiliary power source. It also contains a power block for energy conversion consisting of a boost converter connected with the main source and a boost-buck converter connected with the auxiliary source. The converters share the same dc bus, which is connected to the traction motor through an inverter. These power converters must be controlled to meet the following requirements: 1) tight dc bus voltage regulation, 2) perfect tracking of the SC current to its reference, and 3) asymptotic stability of the closed-loop system. A nonlinear controller is developed, on the basis of the system nonlinear model, making use of Lyapunov stability design techniques. The latter accounts for the power converters' large-signal dynamics and for the FC nonlinear characteristics. It is demonstrated using both a formal analysis and simulations that the developed controller meets all desired objectives.

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Modeling and Nonlinear Control of a Fuel Cell/Supercapacitor Hybrid Energy Storage System for Electric Vehicles

The performance of batteries as uninterruptable power sources in any industry cannot be taken for granted. The failures in battery systems of safety-related electric systems can lead to performance deterioration, costly replacement, and, more importantly, serious hazards. The possible failures in battery systems are currently determined through periodic maintenance activities. However, it is desirable to be able to detect the underlying degradation and to predict the level of unsatisfactory performance by an online real-time monitoring system to prevent unexpected failures through early fault diagnosis. Such an online fault diagnosis method can also contribute to better maintenance and optimal battery replacement programs. A robust nonlinear estimator-based online condition monitoring method is proposed to determine the state of health of the battery systems online in industry. Real-world experimental data of a modern battery system are used to assess the efficiency of the proposed approach in the existence of parameter uncertainties.

Online Condition Monitoring of Battery Systems With a Nonlinear Estimator

Automotive vehicles are becoming increasingly dependent on electric power, and this trend will accelerate The health of the vehicular electric power generation and storage (EPGS) system is crucial to enhance vehicle safety, fuel economy, and reliability In this paper, a fault detection and isolation method is presented for the automotive EPGS system, focusing on alternator related faults Parity relations and structured residuals are designed using principal component analysis techniques Real-time implementation and validation of the diagnostic algorithm have been successfully conducted by utilizing an automotive EPGS system test bench

Fault diagnosis of automotive electric power generation and storage systems

Hybrid electric vehicles (HEVs) currently use Nickel-Metal Hydride (Ni-MH) batteries which have advantages of design flexibility, superior power, environmental acceptability and recyclability, long life, wide-range operating temperature and low cost. No matter how good a battery is, a failure can always occur in a battery leading to serious inconvenience, performance deterioration and costly replacement. Thus, it is desirable to be able to detect the underlying degradation and to predict level of unsatisfactory performance. By using current, voltage and temperature measurements of Ni-MH batteries, they can be modeled so that the internal dynamics of the batteries can be estimated and state of health of the batteries can be predicted for secure and long-life operations. An observer-based fault diagnosis approach is designed to analyze the state of health of the Ni-MH battery system of HEVs in this study. Real-world input data is used to assess the efficiency of the approach in the existence of uncertainties. The possible sensor faults and unexpected parameter deviations are diagnosed efficiently with statistical evaluation of the generated residuals.

An observer-based fault diagnosis in battery systems of hybrid vehicles

This paper deals with a Lyapunov based control principle in a hybrid energy storage system for electric vehicle. The storage system consists on fuel cell (FC) as a main power source and a supercapacitor (SC) as an auxiliary power source. The power stage of energy conversion consists on a boost converter connected with the main source and a buck-boost converter connected with the auxiliary source. The converters share the same dc bus which is connected to the traction motor through an inverter. The aim is controlling power converters in order to satisfy the following requirements: i) tight dc bus voltage regulations, ii) perfect tracking of SC current to its reference, and iii) asymptotic stability of the closed loop system. It is clearly shown, using formal analysis and simulations that the designed controller meets all the objectives.

/pdf/lyapunov-based-control-of-hybrid-energy-storage-system-in-1giu2e7wyx.pdf

Lyapunov based control of hybrid energy storage system in electric vehicles

In the automotive industry, the direction is toward increased use of electricity to improve fuel efficiency, emissions, reliability, and consumer demand for on-board electronics. Hybrid systems use electric motor assist for propulsion with battery storage energy from various possible sources, including inductive recharging from home power, regenerative braking, or fuel cells, among others. There was a great deal of research, begun by the automotive manufacturers, on increasing system voltage from the conventional 12 to 42 Vdc. This has subsequently been stopped because of the significant cost increases that would need to be passed on to the consumer. Presently, the direction is toward hybrid gas/electric motors for improved fuel economy. This book, Vehicular Electric Power Systems, presents a description of the latest systems being proposed for electric power conversion in automobiles, aircraft, boats, and spacecraft. The authors provide a good comparison between presently used conventional systems and new systems along with the fundamental issues holding back some of the proposed technologies. The book, consisting of 13 chapters, begins with a good review of conventional and advanced power electronics fundamentals and electric machines. These cover AC/DC, DC/DC, DC/AC, and AC/ AC converters and advancements in power electronics and motor drives. The next two chapters cover automotive power systems, including a comparison of conventional drive systems to hybrid electric cars. By illustrating the various drive distribution systems being proposed and their design tradeoffs, the reader gets a good understanding of the road blocks presently facing designers. Descriptions not only include propulsion systems themselves but also cover ancillary systems, such as power-assist steering and braking systems, needed to improve efficiency. Other chapters cover advanced power generation systems for aircraft and electric ships. Regarding the international space station, the primary technology discussed is photovoltaic (PV) systems with batteries and flywheel technologies as secondary energy sources. There is an extensive review of spacecraft power system architecture with emphasis on PV power conversion techniques and system stability analysis. Sea and undersea power systems cover various power system architectures along with power management centers and distribution, new motors. One chapter is devoted to descriptions of the fuel cell technologies along with typical current-voltage curves and performance for the various types of cells. The end of the book contains some of the more practical and more specific information on modeling batteries, PV cells, ultracapacitors, and fuel cells along with detailed motor drive descriptions. The authors present excellent reviews of proposed technology, which is particularly useful, as it is compared with conventional technology. One potential issue with presenting up-and-coming technology is the potential that it will not be completed. This appears to be the case with 42Vdc conversion. So, although there is some lack in being up-to-date, as 42V power net systems are no longer emphasized in automotive, the book is still an excellent way for an engineer, manager, or student in the area of electric vehicle propulsion and power systems to learn about new technologies and road block issues.

J.J. Shea

Papers

Vehicular electric power systems [book review]