Enhanced Availability of Drivetrain Through Novel Multiphase Permanent-Magnet Machine Drive

This paper deals with a novel multiphase permanent-magnet (PM) machine drive to enhance drivetrain availability in electric traction applications. It describes the development of new winding configurations for six-phase PM brushless machines with 18 slots and eight poles, which eliminate and/or reduce undesirable space harmonics in the stator magnetomotive force. In addition to improved power/torque density and efficiency with a reduction in eddy current loss in rotor PMs and copper loss in end-windings, the developed winding configuration also enhances availability of drivetrain, in a variety of applications requiring a degree of fault tolerance, by employing it as two independent three-phase windings in a six-phase interior-PM machine, which is designed and optimized for a given set of specifications for an electric vehicle, under thermal, electrical, and volumetric constraints. This paper also describes the design and development of a six-phase inverter with independent control for both sets of three-phase windings. The designs of the motor and the inverter are validated by a series of preliminary tests on the prototype machine drive

A multi-port power conversion system for the more electric aircraft

In more electric aircraft (MEA) weight reduction and energy efficiency constitute the key figures. Additionally, the safety and continuity of operation of its electrical power distribution system (EPDS) is of critical importance. These sets of desired features are in disagreement with each other, because higher redundancy, needed to guarantee the safety of operation, implies additional weight. In fact, EPDS is usually divided into isolated sections, which need to be sized for the worst-case scenario. Several concepts of EPDS have been investigated, aiming at enabling the power exchange among separate sections, which allows better optimization for power and weight of the whole system. In this paper, an approach based on the widespread use of multi-port power converters for both DC/DC and DC/AC stages is proposed. System integration of these two is proposed as a multiport power conversion system (MPCS), which allows a ring power distribution while galvanic isolation is still maintained, even in fault conditions. Thus, redundancy of MEA is established by no significant weight increase. A machine design analysis shows how the segmented machine could offer superior performance to the traditional one with same weight. Simulation and experimental verifications show the system feasibility in both normal and fault operations

Study of challenges in technology development and market penetration of hybrid electric vehicles in Canada

Growing concerns of the economic and environmental impact of petroleum combustion by on-road transportation have accelerated the development of alternative fuel vehicles; of these, the hybrid electric vehicle (HEV) is currently the most commercially successful technology. It integrates an electric drivetrain to the internal combustion engine for optimized engine operation giving significantly higher fuel efficiency and lower emissions. However, despite their well recognized benefits, Canadian consumers have shown reluctance in adapting HEVs so far. This thesis discusses the immediate need for Canada to adopt more efficient and eco-friendly transportation systems and analyzes the cost effectiveness and tailpipe emissions of HEVs that offer a suitable alternative. The factors inhibiting market acceptance of hybrids are have been reviewed and a set of comprehensive policy guidelines and measures have been proposed to provide financial incentives, enforce emission regulations and support technology development of hybrid vehicles. As part of the highlighted target, challenges in key areas of HEV technology have been discussed and one such challenge is addressed by proposing a more robust electric motor drive for vehicle traction

Cost of energy optimisation of offshore wind turbine pmg drive trains based on uncertainty

Offshore wind is a constantly evolving industry as the demand for clean renewable sources of energy continues to grow globally. The cost of energy (COE) is measure of the cost per unit of energy supplied by a provider over the lifetime of a project. Methods in which to reduce this cost are always a priority for parties involved in the design, installation and operation of a wind farm. This thesis explores the contribution of wind turbine drive train design and optimisation in the reduction of COE whilst providing a review of the most sensitive design parameters.Chapters 1 and 2 provide the background to the COE calculation for offshore wind turbines and introduces some of the key issues with current models and challenges for creating reliable designs. Chapter 3 outlines the COE model methodology and introduces base case results for 4 different drive trains with permanent magnet generators (three geared designs and one direct drive topology without a gearbox). Chapter 4 provides an optimisation process based on a genetic algorithm to allow the design to be improved whilst considering several constraints. Chapter 5 looks at the optimised designs under different price input conditions to assess the impact on the COE. Chapter 6 introduces the concepts of robust optimisation and optimisation under uncertainty to account for price variability associated with material used in the drive train.This thesis provides a novel approach to drive train optimisation whilst accounting for price uncertainty. The study highlights the key vulnerabilities for a design under material price fluctuations and presents design processes which include uncertainty and provide robust solutions for various drive train topologies.The effect of drive train design and optimisation suggests that direct drive topologies (that do not have a gearbox) can offer the lowest COE solutions. This is primarily due to the increase in reliability achieved by eradicating the failures associated with wind turbine gearboxes. This result supports current trends observed in large offshore wind turbines where many of the installed >6MW machines are direct drive permanent magnet generators. Additionally, a well-designed drive train has the potential to reduce the COE by up to 15% as discussed in this thesis.Offshore wind is a constantly evolving industry as the demand for clean renewable sources of energy continues to grow globally. The cost of energy (COE) is measure of the cost per unit of energy supplied by a provider over the lifetime of a project. Methods in which to reduce this cost are always a priority for parties involved in the design, installation and operation of a wind farm. This thesis explores the contribution of wind turbine drive train design and optimisation in the reduction of COE whilst providing a review of the most sensitive design parameters.Chapters 1 and 2 provide the background to the COE calculation for offshore wind turbines and introduces some of the key issues with current models and challenges for creating reliable designs. Chapter 3 outlines the COE model methodology and introduces base case results for 4 different drive trains with permanent magnet generators (three geared designs and one direct drive topology without a gearbox). Chapter 4 provides an optimisation process based on a genetic algorithm to allow the design to be improved whilst considering several constraints. Chapter 5 looks at the optimised designs under different price input conditions to assess the impact on the COE. Chapter 6 introduces the concepts of robust optimisation and optimisation under uncertainty to account for price variability associated with material used in the drive train.This thesis provides a novel approach to drive train optimisation whilst accounting for price uncertainty. The study highlights the key vulnerabilities for a design under material price fluctuations and presents design processes which include uncertainty and provide robust solutions for various drive train topologies.The effect of drive train design and optimisation suggests that direct drive topologies (that do not have a gearbox) can offer the lowest COE solutions. This is primarily due to the increase in reliability achieved by eradicating the failures associated with wind turbine gearboxes. This result supports current trends observed in large offshore wind turbines where many of the installed >6MW machines are direct drive permanent magnet generators. Additionally, a well-designed drive train has the potential to reduce the COE by up to 15% as discussed in this thesis