Dean Patterson

Use of lithium-ion batteries in electric vehicles

An account is given of the lithium-ion (Li-ion) battery pack used in the Northern Territory Universitys solar car, Fuji Xerox Desert Rose, which competed in the 1999 World Solar Challenge (WSC). The reasons for the choice of Li-ion batteries over silver–zinc batteries are outlined, and the construction techniques used, the management of the batteries, and the battery protection boards are described. Data from both pre-race trialling and race telemetry, and an analysis of both the coulombic and the energy efficiencies of the battery are presented. It is concluded that Li-ion batteries show a real advantage over other commercially available batteries for traction applications of this kind.

The design and development of an axial flux permanent magnet brushless DC motor for wheel drive in a solar powered vehicle

Fig. 1. The “Desert Rose” on the road. presented here is based on a high-performance solar vehicle, many of the issues addressed are applicable to conventional, battery powered vehicles. The paper presents a review of electric propulsion characteristics and wheeled vehicle physics with an emphasis on the solar application. A weight-power tradeoff forms the basis for the in-wheel drive design which is discussed in detail. Experimental results for a 1-kW machine verify the design concepts introduced.

Design and simulation of a permanent-magnet electromagnetic aircraft launcher

This paper describes the basic design, refinement, and verification using finite-element analysis, and operational simulation using the Virtual Test Bed, of a linear machine for an electromagnetic aircraft launcher, for the aircraft carrier of the future. Choices of basic machine format and procedures for determining basic dimensions are presented. A detailed design for a permanent-magnet version is presented, and wound-field coil and induction machine versions are briefly discussed. The long armature-short field geometry is justified, and in particular the impact of this geometry on the scale of the power electronic drive system is examined.

Design and simulation of an electromagnetic aircraft launch system

Electric actuators are increasingly supplanting or replacing mechanical actuators (steam or hydraulic) in ship systems. This trend started in commercial shipping, especially cruise ships, and there is now a move to adopt the benefits in military systems. This paper describes the design and analysis of a very large actuator for a military ship system an Electro-Magnetic Aircraft Launching System, or EMALS, which will accelerate aircraft to flight speeds in very short distances. The aim is to replace the steam catapult currently used on aircraft carriers with a linear electric motor. The entire system should fit within the confines of the existing steam catapult. The advantages of such a system are increased operational availability, lower airframe stress due to programmable acceleration profiles, and reduced maintenance (and hence reduced manning). The goal of the study described here is to investigate the many feasible solutions and to use simulations to compare their performance. This paper reports on the initial stages of the work, which uses the Virtual Test Bed (VTB) as the simulation and virtual prototyping environment. This yields substantial side benefits because the EMALS research program represents a meaningful test case for the VTB itself. Models of the different parts of the systems are being built up from the specifications and the characteristics required by the US Navy, and will be refined with increasing detail as the project is developed.

An efficiency optimized controller for a brushless DC machine, and loss measurement using a simple calorimetric technique

This paper describes the design, construction and testing of an efficiency optimised controller for a purpose designed axial flux permanent magnet machine. The testing and measurement is carried out using a new, simple, indirect calorimetric technique. This technique is very inexpensive, and is capable of very high accuracy. In this paper losses in the range of 4 to 34 W are measured with errors of approximately 0.1 W, while the controller is processing power of up to 1 kW. Further refinements to the technique are introduced and discussed.<<ETX>>

A comparison of radial and axial flux structures in electrical machines

This paper explores the comparative advantages and disadvantages of the simplest form of axial flux geometry, the single sided version, compared to the most common form of radial flux geometry with an inside rotor, when considering permanent magnet synchronous machines. A detailed literature review of comparisons is presented. New material is presented highlighting the benefits of single sided axial flux geometry. The constraints and assumptions made when comparing possibilities are discussed in detail, including a study of the biases these can introduce. The basis of this comparison is founded on constant electromagnetic airgap shear stress, being the product of electric loading and magnetic loading, and indeed the constancy of both of those factors. The metric used for comparison is simply that of the masses of the active materials, steel, copper, and magnet material. Examples are presented, including a machine which recently went into production in quantity. A range of lesser issues which are relevant when one is making a choice, are presented and discussed.

Electrical system design for a solar powered vehicle

Two separate electrical system designs for a solar-powered vehicle built for a race across Australia in November 1987 are described. A third system for a second race in November 1990 is also described. The design of motors, motor controllers, DC-DC power converters, and maximum power point trackers (MPPTs) under a specialized set of criteria is discussed.<<ETX>>

Single Stage Brushless DC Motor Drive with High Input Power Factor for Single Phase Applications

This paper proposes a single stage topology suitable for small to medium power systems with high inertia loads such as home appliances. This approach features a single controlled power stage which implements both conventional brushless DC motor speed control and a novel power factor correction strategy. This approach eliminates the Boost Unity Power Factor (UPF) stage and bulk electrolytic capacitor typically used for single phase applications. With an appropriate current modulation strategy, the input current can be shaped and high input power factor can be obtained. Design equations are derived, a comparison with the conventional two-stage approach is performed and simulation and experimental results are presented.

Permanent magnet generator design and control for large wind turbines

Direct drive permanent magnet generators(PMGs) are increasingly capturing the global wind market in large onshore and offshore applications. The aim of this paper is to provide a quick overview of permanent magnet generator design and related control issues for large wind turbines. Generator systems commonly used in wind turbines, the permanent magnet generator types, and control methods are reviewed in the paper. The current commercial PMG wind turbine on market is surveyed. The design of a 5 MW axial flux permanent magnet (AFPM) generator for large wind turbines is discussed and presented in detail.

A high power, current sensorless, bi-directional, 16-phase interleaved, DC-DC converter for hybrid vehicle application

A 16-phase interleaved bidirectional DC/DC converter is presented featuring smaller input/output filters, faster dynamic response and lower device stress for hybrid vehicle applications. This converter is connected between the ultracapacitor (UC) pack and the battery pack in an energy storage system of a hybrid vehicle. Typically, multi-phase interleaved converters require a current control loop in each phase to avoid current imbalance among phases. This increases system cost and control complexity. In order to minimize imbalance currents and remove the current control loop in each phase, the converter is designed to operate in the discontinuous conduction mode (DCM). The high current ripple associated with DCM operation is then alleviated by interleaving. The design, construction and testing of an experimental hardware prototype is presented, with the test results included. Finally, a novel soft switch topology for DCM operation is proposed for future research, to achieve zero-voltage switching (ZVS), or zero-current switching (ZCS) in all transitions.