K. L. Butler

A Matlab-based modeling and simulation package for electric and hybrid electric vehicle design

This paper discusses a simulation and modeling package developed at Texas A&M University, V-Elph 2.01. V-Elph facilitates in-depth studies of electric vehicle (EV) and hybrid EV (HEV) configurations or energy management strategies through visual programming by creating components as hierarchical subsystems that can be used interchangeably as embedded systems. V-Elph is composed of detailed models of four major types of components: electric motors, internal combustion engines, batteries, and support components that can be integrated to model and simulate drive trains having all electric, series hybrid, and parallel hybrid configurations. V-Elph was written in the Matlab/Simulink graphical simulation language and is portable to most computer platforms. This paper also discusses the methodology for designing vehicle drive trains using the V-Elph package. An EV, a series HEV, a parallel HEV, and a conventional internal combustion engine (ICE) driven drive train have been designed using the simulation package. Simulation results such as fuel consumption, vehicle emissions, and complexity are compared and discussed for each vehicle.

Application of electrically peaking hybrid (ELPH) propulsion system to a full-size passenger car with simulated design verification

An electrically peaking hybrid electric (ELPH) propulsion system is being developed that has a parallel configuration. A small engine is used to supply power approximately equal to the average load power. The operation of the engine is managed by a vehicle controller and an engine controller such that the engine always operates with nearly full load-the optimal fuel economy operation. An induction motor is used to supply the peaking power required by the electrically peaking load. The motor can also absorb the excess power of the engine while the load power is less than the peak. This power, along with the regenerative braking power, can be used to charge the batteries on board to maintain the battery state-of-charge (SOC) at a reasonable level. With the electrically peaking principle, two control strategies for the drive train have been developed. One is called maximum battery SOC control strategy, by which the engine and electric motor are controlled so that the battery SOC is maintained at its top level as much as possible. This control strategy may be used in urban driving in which accelerating and decelerating driving is common and high-battery SOC is absolutely important for normal driving. The other control strategy is called engine turn-on and turn-off control by which the engine is controlled to operate in a turn-on and turn-off manner. This control strategy may be used in highway driving. Based on the ELPH principle and the drive train control strategies, a drive train for a full-size five-seat passenger car has been designed and verified using the V-ELPH computer simulation package.

Network Reconfiguration for Service Restoration in Shipboard Power Distribution Systems

The electric power systems of U.S. Navy ships supply energy to sophisticated systems for weapons, communications, navigation, and operation. Circuit breakers (CBs) and fuses are provided at different locations for isolation of faulted loads, generators, or distribution system from unfaulted portions of the system. These faults could be due to widespread system fault resulting from battle damage or material casualties of individual loads or cables. After the faults and subsequent isolation of the faults, there will be unfaulted sections that are left without supply. Fast restoration of supply to these unfaulted sections of the shipboard power system (SPS) is necessary for system survivability. This article presents a new method to reconfigure the network to restore service to unfaulted sections of the system. The problem is formulated as a variation of the fixed charge network flow problem. The method is illustrated using various case studies on a small power systems with topology similar to a shipboard power system.

An investigation of electric motor drive characteristics for EV and HEV propulsion systems

The recent growing interest in electric vehicle (EV) and hybrid electric vehicle (HEV) demands for an efficient, reliable and economical motor drive for electric propulsion. However, searching for a suitable traction motor becomes quite involved when vehicle dynamics and system architecture are considered. This paper makes an in-depth investigation on two highly important traction motor characteristics, extended speed rangeability and energy efficiency, from vehicular system perspective. The influences of these two motor drive features on a pure EV, a post-transmission, and two pretransmission parallel HEV with 20% and 50% hybridization are studied in this paper. Two EV-HEV software packages ‘V-ELPH’ developed by Texas A&M University and ‘ADVISOR’ from NREL are used for simulation purposes. Based on the results in this paper, a systematic method is developed regarding the selection of traction drives for EV and HEV propulsion systems.

A Comparison Study Between Two Parallel Hybrid Control Concepts

Two parallel HEV control concepts: ‘thermostat’ and ‘power split’ are compared in this paper. To achieve a substantial improvement in fuel economy, the ‘thermostat’ or ‘on/off’ control technique intended to improve the fuel efficiency of a series HEV has been adopted and designed for parallel HEV. Among different ‘power split’ concepts developed for parallel hybrids only the ‘electrically assist’ algorithm is considered in this paper. These two control concepts are compared for three parallel HEV architectures: pre-transmission, post-transmission and continuous variable transmission hybrids. The comparison study also includes the effect of hybridization factor—the ratio of the electric power to the total propulsion power. The matrices of comparison are level of performance, energy consumption and exhaust emissions. The SAE J1711 partial charge test procedure is followed. The full hybrid propulsion system is simulated using two EVHEV software packages: ‘V-ELPH’ developed by Texas A&M University and ‘ADVISOR’ from NREL. Based on the simulation results, the paper defines an optimum range of hybridization factor for the two control concepts.

Effect of Extended-Speed, Constant-Power Operation of Electric Drives on the Design and Performance of EV-HEV Propulsion System

Vehicle dynamics requires extended-speed, constantpower operation from the propulsion system in order to meet the vehicle’s operating constraints (e.g., initial acceleration and gradeability) with minimum power. Decrease in power rating will decrease the volume of the energy storage system. However, extending the constant power operating range of the electric drives increases its rated torque, thereby, increasing motor volume and weight. This paper investigates the effect of extended constant power operation on battery driven electric vehicle (BEV) propulsion system taking the change in motor weight and battery volume into account. Five BEV systems with five traction drive having different base speeds are simulated for this study. The performances of the BEVs are obtained using FUDS and HWYFET drive cycles. Two EV-HEV software packages ‘V-ELPH’ developed by Texas A&M University and ‘ADVISOR’ from NREL are used for simulation testing. Based on the simulation results, the paper defines an optimum range of the constant power region for single gear operation.

Relative performance of clustering-based neural network and statistical pattern recognition models for nondestructive damage detection

The objective of this paper is to compare and contrast the capabilities of neural networks and statistical pattern recognition to localize damage in three-dimensional structures. A theory of damage localization, which yields information on the location of the damage directly from changes in mode shapes, is formulated. Next, the application of statistical pattern recognition and neural networks for nondestructive damage detection (NDD) is established. Expressions for classification using linear discriminant functions and a two-stage supervised clustering-based neural network are generated. Damage localization is applied to a finite-element model (FEM) of a structure which contains simulated damage at various locations. A set of criteria for comparing and contrasting statistical pattern recognition and neural network models is then established. Finally, the evaluation of the two models is carried out using the established criteria.

Experimental results from short-circuit faults on a distribution transformer

In an effort to characterize the behavior of the terminal values (primary and secondary voltages and currents) of a distribution transformer during internal short circuit and incipient faults, experiments were performed on a custom-built transformer. This single phase 25 kVA, 7200 V/240 V/120 V two winding transformer included twelve taps distributed on turns along the primary winding and similarly 12 taps distributed along the secondary winding for the purpose of staging faults that involved short circuits of sections of winding turns. The experiments were performed at the downed conductor testing facility at Texas A&M University (USA) over a 19 month period. This paper describes the experimental setup and presents and discusses the results obtained during the experiments.

Network reconfiguration for service restoration in shipboard power distribution systems

Summary form only given, as follows. The electric power systems of US Navy ships supply energy to sophisticated systems for weapons, communications, navigation and operation. Circuit breakers (CBs) and fuses are provided at different locations for isolation of faulted loads, generators or distribution system from unfaulted portions of the system. These faults could be due to widespread system faults resulting from battle damage or material casualties of individual loads or cables. After the faults and subsequent isolation of the faults, there will be unfaulted sections that are left without supply. Fast restoration of supply to these unfaulted sections of the shipboard power system is necessary for system survivability. This paper presents a new method to reconfigure the network to restore service to unfaulted sections of the system. The problem is formulated as a variation of the fixed charge network flow problem. The method is illustrated using various case studies on a small power system with a similar topology to a shipboard power system.