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Contact behavior of electrical vehiclebattery junction box under high shorting and breaking current
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0639
The motor of an electric vehicle and its equipment are connected to the battery via a junction box that contains power relays that ensure current flow when closed but can break the current in abnormal situations. The contacts of such relays have to ensure and maintain a low contact resistance and support a shorting current of a few kA and an acceptable breaking capacity under a normal load of a few hundred amps. We have developed a test involving a shorting current of 4000A passing during 50ms through closed contacts in which we study welding and arcing phenomena. The origin of arcing has been attributed to the shorted contact produced by the electromagnetic repulsion force that is able to counterbalance the contact force and separate the contact. The power arcing burns during the short circuit and a irreversible damage is observed when the accumulated arc energy exceeds a certain critical value. In this paper, the main cause of the repulsion phenomena and minimum arc energy criteria inducing substantial damage and capsule breaking is studied. By varying conditions of current for two relays equipped with different materials, filled with a specific gas and employing a magnetic field we found that shorting damage was not avoided below 2KJ. Fortunately breaking capacity is achieved without damage and relay function is ensured.

Comparative analysis of unbalanced magnetic force in fractionalslot permanent magnet machines having external rotor topologies
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0272
This paper comparatively investigates the unbalanced magnetic force (UMF) of external rotor machines having pole and slot numbers differed by one but no rotor eccentricity. The 8pole/9slot and 10pole/9slot machines are firstly optimised for maximum torque density by nonlinear FE analysis. Then, the UMF of both machines are analysed by both analytical model and linear FE model. It shows that the optimised 10pole/9slot machine has larger average torque than the 8pole/9slot machine for the same copper loss. However, the 10pole/9slot external rotor machine has significantly larger UMF than the 8pole counterpart, which is opposite to the case of internal rotor machines. (6 pages)

A linear superconducting generator for wave energy converters
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0298
Directdrive superconducting linear generators can be an alternative for wave energy converter power takeoff systems. A novel superconducting generator topology is presented in this paper. The generator has a stationary superconducting field winding fixed to modular magnetic cores. The translator is composed of aircored copper windings. The generator is suitable for lowspeed, hightorque applications. A 640 kW linear generator is designed. The design is validated using FEA tools and the specifications of the generator are presented. (6 pages)

Torquespeed performance analysis of fractional slot PM machines having concentrated windings using alternate methods
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0273
Due to high torque density and efficiency, permanent magnet (PM) machines are widely utilized in industrial and commercial applications for all power ranges. When they are operated at high electric loading, the influence of magnetic saturation is usually large. Furthermore, due to the geometric structure of some PM machine topologies, e.g. interior PM machines, such influence can be even more significant. The partial crosscoupling model, which considers that the PM flux is a function of qaxis current and the d and qaxis inductances are functions of d and qaxis currents, respectively, is simple but neglects the saturation to some extent. However, as shown by the frozen permeability method in this paper, it can accurately predict the torquespeed characteristics of fractionalslot PM machines having concentrated windings. The analysis is confirmed by experimental results. (6 pages)

Acoustic noise and vibration of directtorquecontrolled permanent magnet brushless DC drives
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0264
A systematic approach to identify the vibration and acoustic noise sources in a directtorquecontrolled (DTC) PM BLDC drive is presented and compared with that in BLAC DTC drive. Experimental results show that the acoustic noise may be radiated by the radial vibration of the stator and the vibration of connected mechanical parts due to torque pulsation and stator torsional vibration. In the BLDC DTC prototype drive, the interaction between the field harmonics and PWM switching current harmonics appears to be the dominant source of radial vibration and acoustic noise. If the acoustic noise in both BLDC DTC and BLAC DTC is mainly caused by the interactions between the armature reaction field harmonics themselves, and between the armature reaction field harmonics and PM field harmonics, the BLDC DTC drive is expected to produce higher acoustic noise because the phase current and hence the armature reaction field of BLDC DTC drive is rich of nontriplen odd harmonics. However, if the acoustic noise radiated from BLDC DTC and BLAC DTC drives is largely attributed to PWM switching current harmonic induced vibrations, as found in this paper, the sound pressure level in a BLDC DTC drive may be lower than its BLAC counterpart. (6 pages)

Motion control strategy and operational behaviour of a high speed bearingless disc drive
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0297
In the last decade, bearingless drives have found their way into applications such as pumps for delicate media like blood [1] or sensitive chemicals [9] as well as drives for bioreactors [13] and chemical process chambers [3]. With all these applications running at relatively low speeds below 15.000rpm, the suitability of bearingless drives for high speed operation remained unclear. This paper will give a brief description of a high speed bearingless disc drive, designed to reach speeds beyond 100.000rpm. Aside from special requirements such as rotor material strength and low stator loss characteristics, the control system also faces new tasks arising from the combined motor  bearing unit. Eventually, the operational behaviour of the constructed prototype on the basis of phase current amplitude and resulting rotor orbit is presented. (6 pages)

Investigation into the temperature profile of a liquid cooled YASA© AFPM machine
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0281
The developments in Axial Flux Permanent Magnet (AFPM) machines enable higher torque and power densities and higher efficiencies, thus making it a suitable candidate for various applications such as electric road transportation or wind energy generation. Due to the fact that liquids have a higher thermal capacity than air, liquid cooling has been used in high power radial flux electrical machines. This typically involves water being passed through a series of channels in the casing, which will be in thermal contact with the stator. Such a cooling configuration presents a number of thermal resistances between the heat source and the heat sink, limiting the heat transferred and hence the performance of the machine. The knowledge developed for radial flux machines, has been transferred to the design of AFPM machines, with the cooling channels embedded in the stator iron or in the stator plate for single rotor machines. Such liquid cooled machines rely on aircooling for the copper end windings. The scope of this work is to present a temperature profile for a pole piece for a liquid cooled stator in YASA© electric machine. A highresolution lumpedcapacity thermal model is also presented, and compared to the experiment. The paper shows how a highresolution model can reveal much more valuable information on the thermal aspects of the stator. (8 pages)

Field correlation between electromagnetic and high flux stator core tests
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0144
In stator core interlamination insulation fault tests, there is a commonplace expectation that the Quad signal detected by EL CID is correlated to the high flux test, at the rate of 510°C/100 mA. Evidence to date has been supportive but inconclusive. A new opportunity has been taken to review 106 reported core fault test results from the field on turbo and hydrogenerators, where both tests were conducted on the same fault. A number of normalisation corrections were proposed and applied, which resulted in the population mean trend correlation lying between 8.510.7°C/100 mA with a 95% confidence factor. The central quartiles embrace the 612°C/100 mA range, close to the expected rate. (6 pages)

The impact of variable and fixed DC supplies on the design of EV traction drives
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0194
Electric vehicles (EV's) are a gradually growing field for electric traction machines due to energy and environmental related constraints [1, 2]. The traction system of an EV consists of an electric traction machine (TM), power conversion electronics and energy source(s). The energy source(s) provide a DC link supply for the traction system. The impact on the electric traction machine design from the DC link variation is investigated in this paper. (2 pages)

Rotor losses in laminated magnets and an anisotropic carbon fiber sleeve
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0282
High speed fault tolerant permanent magnet machines have strong asynchronous airgap harmonics, making them susceptible to rotor eddycurrent losses. These losses can be reduced by using novel high resistivity materials like plastic bonded magnets and carbon fiber reinforced retaining sleeves. This paper examines by numerical studies the consequences for the losses of using these materials. The effect of laminating the magnets and the losses in the anisotropic sleeve are analysed with 3D simulations, using simplifications determined with 2D simulations. The anisotropic resistivity of the sleeve roughly doubles the losses compared to an isotropic sleeve, while laminating the magnets in n slices reduces the losses by 1/n<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">1.8</sup>. (6 pages)

A extendedrange hybrid powered scooter
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0355
As the electric scooter market grows, one of the major problems facing designers of pure EVs is getting sufficient range from batteries that can't cope with long journeys. The alternative is to have a range extender of hybrid powered scooter in which a small size of fuel cell stack combines with a battery powered electric motor. However, in such models, electriconly range is restricted to just a few miles. However, adding a small rangeextender fuel cell to drive a hybrid power output or charging the battery when idle or low power periods allows range to be increased to an increase of miles. The problem with this solution, though, is cost. This paper shows both the modelling and simulation of a hybrid powered scooter and the experimental results. There is other, more detailed feasibility on fuel cell rangeextender for a hybrid powered electric scooter. In experimental data, the result of electric scooter can unceasingly run by increasing the range from 100 kilometres to 126 kilometres at a fixed speed of 45 km per hour with a PEMFC of range extender by using 134 litres of hydrogen fuel. The experimental data are also compared with the pure battery powered scooter. Not only can the range of adding a small size of fuel cell be increased further, but also the test performance can be more brilliant than that of a pure battery powered scooter. (7 pages)

A comparison of cage and nestedloop BDFM rotors
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0294
The Brushless DoubleFed Machine (BDFM) is a type of variable speed generator or drive. Using theoretical analysis of simple BDFM rotors this paper establishes trends in how rotor structures determine the rotor's equivalent circuit resistance, leakage inductance and turns ratio. The variation in measured parameters of five prototype rotors is then analysed in light of the trends found. Both the theory and experimental results suggest a significant performance advantage in using cage+loops type rotors as opposed to the simple nested loop type more usually employed. (6 pages)

An innovative oil immersed power stack for wind power conversion using series connected GCTS
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0242
A novel 450 kW DC wind power generator has been built using Active Stator technology, with an integrated oil immersed power electronic converter. The converter utilises unpackaged series connected Reverse Blocking Gate Commutated Thyristors (RBGCT), operating at unity gain, to achieve high power density within a sealed `iCAN' stack enclosure. The stack is cooled with synthetic ester oil which is also utilised as a liquid dielectric to provide 3 kV isolation in a small converter footprint.. The Active Stator machine is capable of operating in four quadrants for either motoring or generating. (5 pages)

Innovative injectionbased 100% stator earthfault protection
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0112
Injectionbased 100% stator earthfault protection has been used for many years. However traditionally signals with frequency between 10Hz and 25Hz have been injected into the stator winding. To inject such a signal, either a dedicated grounding transformer with secondary grounding resistor or injection on primary side of the grounding circuit, is normally used. This paper will present a novel approach to such protection. Injection signal with frequency slightly higher than the power system rated frequency is used (e.g. 87Hz signal in a 50Hz power system). Such signal frequency enables the following advantages for new injectionbased protection: 1. Injection is always performed on secondary side of a transformer. This transformer can be either a grounding transformer or a voltage transformer. Thus no change to the primary grounding circuit of the machine (e.g. splitting of the primary resistor in the star point) is required. 2. Injection via neutral point VT or even via open delta VT located at the generator terminals is possible. This ensures readily available injection point for almost any unitconnected generator. 3. Injection via a VT enables this protection to be applied to ungrounded or inductance/resonance grounded stator windings. 4. Because of the higher injection frequency the injection unit and the injection transformer are relatively small. (6 pages)

Modelling and analysis of electromagnetic torque in direct drive PM machines with rotor eccentricity
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0278
The influence of rotor eccentricity on torque oscillations as well as average output torque of permanent magnet (PM) machines with integral number of slots per pole per phase has been studied using 1dimensional (1D) analytical modelling and 2dimensional (2D) finite element (FE) method. It is shown that cogging and ripple torque are amplified by rotor eccentricity due to the contribution of new flux density components created by eccentricity, while this amplification follows a quadrature function against the eccentricity degree. Furthermore, it is shown that the average electromagnetic torque can be increased by rotor eccentricity provided that magnetic saturation is negligible. The analytical predictions have been validated by FE analysis of a direct drive PM machine. (5 pages)

Comparison of 3 and 9phase brushless PM drive systems for aerospace actuation
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0249
Nearly all electric vehicles (EVs), hybrid electric vehicles (HEVs), more electric aircraft, electric ship propulsion and others power conversion industrial applications uses power electronic inverters to convert AC to DC or vis versa, as in the starter/generator machine system and generation/regeneration process of the traction motor. Also, it has become possible to integrate HEVs power electronics component in one package with one set of liquid cooling. Recently, compactness and reliability of the power conversion and generation system design in automotive, in particular, and in aerospace industries are growing with global necessity of shifting from conventional airborne emission vehicles and aircrafts to the green all electric ones. Therefore, an advanced technology in the area of energy storage, conversion and dclink capacitors, which account for a major fraction of the volume, weight and also cost of the inverter, is demanded by the developer of HEVs and other industrial areas. In threephase system a dclink voltage source inverters (VSI) are fed via controlled or uncontrolled rectifier bridges from a main source. Here, a dclink capacitor is usually used to maintain a stiff dclink voltage across the VSI, and to perform other tasks, as in [1]. Such that, in this application, the dclink capacitor deals with the main voltage fluctuation and provides a dclink current ripple to suppress the generated electromagnetic interface (EMI) caused by pulsating current (ripple current) associated with the inverter switching. It is recognized in the literature [17] that for voltage stiff inverter the dclink capacitor adequate selection, sizing and minimizing presents a major issue for improving electrical system compactness and utilization. Lai et al discusses the use of lowinductance high current film capacitor in a highpower dcbus inverter for batterypowered traction motor drives [2]. Another discussion that shows merits of an advanced film capacitor technology over conventional electrolytic capacitor for dclink applications was presented by Grinberg et al [3]. A dclink capacitor minimization method via direct capacitor current control has been described by Gu and Nam [4]. Such that, the dclink capacitor can be minimized by making the converter side dclink current similar to the inverter side dclink current waveform in a pulse width modulation (PWM) converterinverter system. However, the dclink capacitor reduction technique of Gu et al is not for stiff voltagesource inverter. A simple analytical expression for current stress on the dclink capacitor caused by the loadside inverter of the voltage dclink converter system is derived by Kolar and Round [1]. Conclusions have been obtained by some of the previous papers, which declare that the dclink capacitor of practical systems usually determined by the effective capacitor current stress and not, for example, by a given maximum admissible value of the amplitude of the dclink voltage ripple [1]. In Dahono paper [5], analysis and minimization of output current ripple of multiphase PWM inverters was presented. The minimization of this current ripple is achieved for threephase PWM inverter by injecting a twentyfive percent third harmonic in the reference sinusoidal signal. Whilst, minimization of the output current ripple of a multiphase PWM inverters can not be attained and it will become unsymmetrical if harmonics are injected into the sinusoidal reference signal [5]. Also the paper discussed by Dahono mentioned that multiphase PWM inverters with number of phases equal to multiple of three will give better results than the one that is not a multiple of three, for example, if the number of phases is a multiple of three, the multiphase PWM inverter can be operated as several threephase PWM inverters. As for the authors knowledge, no verification nor investigation of this claim have been found in depth in the literature. In the paper, 3phase and 9phase PWM inverter modules with different threeand ninephase brushless permanent magnet (BLPM) machine configurations will be analysed in detail to show the adequate use of this configuration to either eliminate the need or significantly reduce the size of the dclink capacitor that suppress the generated EMI caused by pulsating current associated with the inverter switching for stiff voltagesource inverter. In addition, different operating points on the general torque speed curve for different BLPM machine drive configurations will be investigated to give decision of the adequate and best machine drive configuration, in terms of improving power and torque capabilities with the minimization of output torque ripple, which can be practically implemented and used in many promising industrial areas. (2 pages)

Thermal modelling of a low speed aircooled axial flux permanent magnet generator
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0271
This paper presents the assessment of air flow in a multistage Axial Flux Permanent Magnet (AFPM) prototype which is set to operate at 100rpm. The CFD models are validated using experimental results to give a greater understanding of the air flow developed in the generator. The proposed ventilation design reduces the pressure loss at the entry resulting in a 10% reduction in maximum stator coil temperature in the CFD modelling. (7 pages)

Optimal split ratio and torque comparison of surfacemounted permanent magnet machines having inner or outer rotor
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0159
Permanent magnet (PM) machines are widely used in many applications. They can have inner (IR) or outer rotor (OR). These two configurations are optimized individually and compared in this paper based on surfacemounted PM (SPM) machines. The optimal split ratio and flux density ratio are derived analytically for both topologies. The analytical models are verified by finite element (FE) analyses. Their optimal designs are compared when they have the same overall size and copper loss. It shows that the OR designs have significantly higher split ratio while the IR designs require much higher flux density ratio for the maximum torque. For SPM applications, the OR designs exhibit higher torque than IR designs. (6 pages)

Torque distribution strategy for a front and rear wheel driven electric vehicle
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0316
Electric vehicles (EVs) with a distributed drive train configuration offer great potential and flexibility for improving the system efficiency, performance, reliability as well as safety. This paper investigates a torque distribution scheme for a front and rear wheel driven EV in order to improve the drive train efficiency over a wide torque and speed range as a part of the EU funded PMOB project. It has been shown the maximum efficiency is achieved if the total torque required by the vehicle is shared equally between the two identical motors. In addition, the distribution of the energy consumption over a New European Driving Cycle (NEDC) is analyzed and the regions of high speed, low torque are identified to have a high level of energy consumption, where the motor efficiency improvement in these regions is the most important. Therefore, this paper further proposes to operate just one motor to provide the total required torque in the low torque region. A clutch may be employed between one motor and gearbox (differential), thus “switching off” its idle loss (noload loss, fluxweakening loss), and improving the drive train efficiency. An online optimized torque distribution algorithm has been devised based on the motor efficiency map to determine whether the second motor should be disengaged by the clutch in the low torque region. With the proposed optimization scheme, the drive train efficiency can be improved by 4% over the NEDC cycle. Experimental test results validate the proposed torque distribution strategy. (6 pages)

A novel electromagnetic core structure for axial radial flux permanent magnet electric motor
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0163
Most of the automobile companies are in to the research and development of electric and hybrid vehicles to promote fuel efficient and environment friendly vehicles. Being one of the major energy consuming part in hybrid and electric vehicles, an electric motor should have high efficiency, high torque density in all the drive cycles and must be compact in design. This paper presents a structure for the permanent magnet electric motor which has both axial and radial magnets and a common electromagnetic core for both. This common core provides path for both axial and radial flux. This structure enhances the magnetic loading and hence developed torque and facilitates more air flow inside the motor. A comparison study on air gap flux and developed torque between motors having conventional core structure and proposed core are presented and these are validates with Finite Element analysis. (6 pages)

Analytical modelling of parasitic force in permanent magnet machines accounting for slotting effect
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0276
Based on the subdomain field model accounting for toothtips, the force distribution and unbalanced magnetic force of surfacemounted PM machines are analytically calculated respectively for opencircuit only, armature reaction only and onload. The finite element results confirm that the developed model has excellent accuracy, while the complex permeance model shows a large error in the predicted unbalanced magnetic force and lowest spatial order harmonic of the force distribution, especially on light load. (6 pages)

Design of high torque traction motors for automotive applications using modulated pole SMC machines
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0311
This paper gives details of an ongoing collaborative project in the area of automotive traction drive machine design. The relationship between electrical frequency, torque, pole number and iron loss in modulated pole machines is investigated with respect to fulfilling an industrially relevant specification. A number of alternative topology configurations are simulated, presented and discussed. (6 pages)

Performance of axial flux permanent magnet generator for human power application
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0306
This paper presents the design and performance of a prototype axial flux permanent magnet generator for human power application. An improved model is developed to achieve better match between measured and predicted performance. Results show that there is good agreement between measured and predicted EMF voltage. However, significant differences still exist between measured and predicted losses especially at low rotational speeds. (5 pages)

An improved torque density Modulated Pole Machine for low speed high torque applications
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0262
This paper presents a new topology for threephase Modulated Pole Machines. This new topology the “Combined Phase Modulated Pole Machine” is analysed and compared to the more traditional technology of three separate single phase units stacked axially with a separation between phases. Three dimensional Finite Element calculations are used to compare performance of the machines under the same conditions, it is shown that the new Combined Phase topology produces a greater torque whilst reducing the number of components required to assemble the machine and increasing its mechanical integrity. (6 pages)

Fidelity requirements in brushless permanent magnet motor modelling
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0277
The paper discusses the development and validation of motor simulation models to aid in the design of actuators for use with automotive variable geometry turbochargers. The specific focus is on the benefit of increasing the fidelity of the motor model, against the tradeoff of increased complexity. Several separate models of the same brushless permanent magnet motor are developed and validated against measurements made from a sample motor. These results, along with the simulation time required for different types of model, are presented and used to draw conclusions on the appropriate fidelity of model for different types of analysis. (6 pages)

A novel permanent magnet motor with large axial channels for downhole applications with hightorque requirements
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0279
The innovative electric motor concept is presented. The main feature of the novel concept is accommodation of relatively large axial channels in a slim electric motor without sacrificing its torque density and radial dimensions. The motor is analyzed and the analysis is then validated by the experiments. The resulting motor performances are given and applications for the motor proposed. (6 pages)

Zerospeed sensorless drive capability of fractionalslot inset PM machine
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0269
This paper investigates the capability of an inset PM motor with concentrated coils fractionalslot winding to be controlled by means of sensorless techniques using high frequency signal injection. The inset PM motor considered is a 12slot 10pole motor, whose performance has been obtained by means of both finite elements simulations and experimental measurements. It will be shown that the motor presents good performance to be controlled by sensorless techniques, and the expected performance agree with the experimental results. (6 pages)

Modelling and analysis of airgap flux density in direct drive PM machines with rotor eccentricity
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0184
The influence of rotor eccentricity on airgap flux density components in directdrive permanent magnet (PM) machines has been studied using 1dimensional (1D) analytical model and 2dimensional (2D) finite element (FE) method. The flux density components have been classified with respect to their MMF and permeance origins, while the rotor eccentricity impact has been decomposed into time and space domains using 2D FFT. Based on the study it is shown that the influence of rotor eccentricity on slotting permeance components is much more significant than that on the PM MMF components, which explain the underestimated increase of the cogging and ripple torque based on 1D analytical model. Furthermore, it is shown that larger rotor eccentricities give rise to more airgap flux density side bands which are expected to contribute to the cogging and ripple torque. (5 pages)

Measurement of heat generation rate in the permanent magnets of rotating electrical machines
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0287
This paper presents an experimental method for measuring heat generation rate in the permanent magnets of rotating electrical machines. The results obtained from the experimental work are used to derive an empirical correlation which is subsequently used to predict the total thermal energy stored in a magnet after a speed varying torque load. The results of an uncertainty analysis are offered in order to show the usefulness of the technique. An axial flux permanent magnet machine has been used as a case study in this work, though the methodology could certainly be applied to other topologies. (6 pages)

Observer based state feedback controller design for pseudo direct drive<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">®</sup> using genetic algorithm
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0263
The paper describes a technique, based on a genetic algorithm GA, for the design and tuning of a state feedback controller with a reduced order observer, for a Pseudo Direct Drive Permanent Magnet Machine PDD. The controller was designed to eliminate torsional oscillations caused by the low stiffness of the magnetic gear, and provide smooth transient and good speed tracking based on ITAE performance index. (6 pages)

Examination of new current control methods for modern PMW controlled AC electric locomotives
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0314
A railway electrification system supplies electrical energy to railway locomotives and multiple units. There are several different electrification systems in use throughout the world. The singlephase AC network systems are widespread (25 kV 50 Hz or 15 kV 16 2/3 Hz). The Hungarian system is 25 kV 50 Hz AC. This article is just dealing with the AC network supplied locomotives. Nowadays in our country the series wound DC traction motor driven locomotives are still widely used. These vehicles are equipped with diode or thyristor rectifier circuits that inject harmonics into the AC line and distort the line voltage. In our work we examined and compared current control methods that can be achieved by "networkfriendly" locomotives connected to distorted line. We worked out a new current control strategy that possesses several advantages. The modern locomotives endeavour to consume sinusoidal current from the AC network, in phase with the network voltage fundamental. In generator mode these endeavour to supply back to the grid sinusoidal current in antiphase to the voltage fundamental. We compared current control methods with this "common" strategy. One of them can reduce the consumed root mean square (RMS) or fundamental current of a distorted line connected modern locomotive in motor mode. Other one can increase the generated RMS and fundamental current in generator mode. With these strategies the harmonic currents can be used for active power. Moreover it turned out that the harmonic content of the network can be reduced by the "new" strategies. For the study, we built a test system. We can model the line side converter of a modern locomotive DClink frequency converter with the system. A common solution in locomotives is when several lineside converters feed two DClinks. In the test system we modelled these with one converter, while the motorside voltage source inverters and the electric traction motors were taken into account as a controllable current source DClink. (5 pages)

High torque density permanent magnet machine for automotive applications
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0186
This paper presents work done on the analysis of a new permanent magnet machine topology using finite element in order to achieve high torque density specifically for an automotive application. Also different types of electric motors that are suitable for automotive applications are shown. A comparison between these different machines is given by highlighting some of their advantages and disadvantages. (6 pages)

Experimental results on a 450 KW active stator machine in a regenerative test RIG
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0285
A dedicated fourquadrant regenerative experimental test rig was built to perform various tests on a 15phase Active Stator machine and its associated drive system. Machine noload characteristics were investigated and a number of onload tests were conducted for both motoring and generating modes of operations. The machine stator winding commutating inductance was calculated using voltage and current data from tests under load conditions and compared with inductance measurements at standstill. Calculated and measured values were in good agreement. Various voltages and currents waveforms were captured on both the network bridge and the machine's electronic commutator. (4 pages)

Interaction between PM rotor design and voltage fed inverter output
http://dllive.theiet.org/content/conferences/10.1049/cp.2012.0274
High performance PM motors must be designed with a consideration of the capabilities of the voltage source inverters that will control them. Both motor and drive are operating at the limits of their capabilities and require accurate estimation of expected performance and losses to enable a successful design. The effect of rotor design choices on VSI performance is shown via the modification of the motor dq equivalent circuits. The inclusion of this coupled effect is shown to be of critical importance in accurately predicting rotor losses during operation. (6 pages)

Sustainable traction drives
http://dllive.theiet.org/content/conferences/10.1049/ic.2011.0188
This paper presents an overview of railway traction systems. Railway vehicles are characterised by low rolling resistance, and high inertia, therefore the traction drives must have suitable capabilities to deliver the required vehicle performance. Both AC and DC motors are in common use in the railway sector, but have very different power delivery requirements, and there are a multitude of power conversion stages that are necessary to transfer the power from the network to the wheels of the vehicle in a smooth manner. These power converters have evolved from simple camshaft controlled mechanical switches, through to compact power electronic converters. Stateoftheart systems are able to regenerate high quality power back into both DC and AC power systems. For those routes which are uneconomic to electrify, the use of on board energy storage offers a means to improve energy efficiency, by providing a store for braking energy which can then be released during acceleration. These types of systems are currently in the development phase, but are expected to enter regular passenger service in the future. Energy storage on the wayside is also being implemented to improve the power performance of existing systems, and to improve the overall energy efficiency by improving the receptivity of the line to regenerated power.

ANFIS based controllers and modeling simulation of PMBLDC
http://dllive.theiet.org/content/conferences/10.1049/cp.2011.0417
The paper presents a tuning methodology for the parameters of adaptive speed controller in a permanentmagnet brushless DC (BLDC) motor and drive system. This study discusses a design of the closed loop drive system employing the adaptivenetworkbased fuzzy interference system (ANFIS) from a mathematical model of the BLDC drive system. The ANFIS based control with nonlinear simulation model of the BLDC motors drive system is simulated in the MATLAB/Simulink platform. The necessary data for training the ANFIS control is generated by simulation of the system with conventional PI controller. The simulated electromagnetic torque and rotor speed signify the superiority of the proposed technique over the classical method.

Numerical simulation of electrical machines by means of a hybrid parallelisation using MPI and OpenMP for FEM
http://dllive.theiet.org/content/conferences/10.1049/cp.2011.0091
In this paper, an hybrid parallelisation approach for the simulation of nonlinear electromagnetic problems by means of the Message Passing Interface (MPI) and the OpenMP Application Program Interface for the Finite Element Method (FEM) is investigated. After an introduction, the metrics applied to evaluate the speedup and the efficiency are outlined. By parallelising the institute's inhouse FEMpackage "/MOOSE" either by MPI or by OpenMP, an evaluation basis for the hybrid approach is being founded. The hybrid parallelisation approach is being evaluated on the high performance computing cluster of university's centre for computing and communication.

DSP implementation of fuzzy based power factor Improvement strategy for a dual converter fed drive
http://dllive.theiet.org/content/conferences/10.1049/cp.2011.0330
The paper embarks to design a fuzzy based control algorithm through the use of a Digital Signal Processor (DSP) to improve the input power factor of a dual converter fed drive system. Th e strategy is created to ensure that the input current vector forcefully follows the source voltage wave in order to arrive at a significant increase in the fundamental component and lowering of the other harmonic components. The methodology is implemented using a suitable prototype and its performance evaluated experimentally over a vi able range of load powers. The results claim an almost unity input power factor and acceptable values in the total harmonic distortion (THD) of the input current, in addition to regulating the speed of the reversible drive through the entire operating horizon.

Global and distributed torque calculations using the CDSA approach
http://dllive.theiet.org/content/conferences/10.1049/cp.2011.0083
Accurate force and torque calculations are fundamental to being able to predict the operation of an electromechanical device or system. In addition, local distributions of torque are needed to couple to structural and vibration analyses. The conventional Maxwell stress approach cannot provide this easily. An approach based on sensitivity analysis has the potential to deliver local stress and torque values. The paper addresses this possibility.

Bootstrapping neural network regression model for motor drive vibration optimization through genetic algorithm
http://dllive.theiet.org/content/conferences/10.1049/cp.2011.0074
This work proposes an optimization procedure based on a bootstrapped neural network interpolation approach and the Genetic Algorithm method. The bootstrapped neural network is used to generate designed data sets in order to estimate a mapping from input to output space in an intrinsic experiment in a motor drive vibration study. The optimization procedure is aimed to minimize the motor vibration by adjusting some drive control parameters.

Speed control of DC motor using Modulus Hugging Approach
http://dllive.theiet.org/content/conferences/10.1049/cp.2011.0418
The speed control of separately excited DC motors by PI and PID controller is widely used in industry. A design of controller by applying a several method in analyzing controlled parameter to tune parameter in order to obtain the best process response. A design of PI and PID controller by Modulus Hugging Approach are presented in this paper for testing the performance of controllers in command following control and in disturbance rejection control. From simulation results with LABVIEW, it was found that the con troller was fast response and stable, and the effect of disturbance is fast rejected.

Characterization of twoaxis equivalent circuit model of PMBLDC motor by FEA
http://dllive.theiet.org/content/conferences/10.1049/cp.2011.0033
It was shown recently that the statevariables averaging method is applicable to permanent magnet brushless DC (PMBLDC) motors and yields an equivalent circuit model analogous to that of the PMBLAC motor. Calculation of the averaged reference frame voltages is difficult, but is crucial for the modeling accuracy. The identification of the averaged (dq) voltages must be carried out using detailed analysis. Here it is done using a dynamic finite element model of an inverterdriven motor. It is shown that these voltages can be modeled by quadratic functions of rotor speed. This lays down the basis for experiment to perform in order to identify these variations. The results obtained from the circuit model compare well with those obtained from the dynamic finite element analysis. Some results from physical model are given.

Experimental based capacitance calculation of induction motor: as wind power generator
http://dllive.theiet.org/content/conferences/10.1049/cp.2011.0350
This paper describes the review of capacitance determination of an induction motor working as generators. An experimental based capacitance value calculation has been propose and implemented successfully in laboratory model of induction generator. A 5Hp, 220V, 15A separately excited d.c motor coupled (mechanically) with a2.2kW, 415V, 4.7A, Yconnected, 1440rpm induction motor emulates the induction generator characteristics with a 50 microfarad capacitor bank (calculated capacitance) connected across the stator windings. For validation of the proposed method, experimentation has been rigup and tested in the laboratory. The result has a good agreement with this method and extends to use of this method, to calculate the additional capacitance required to reduce the reactive power burden in grid connected induction generator, used in wind power( variable speed) generation.

ISO 26262: Experience applying Part 3 to an inwheel electric motor
http://dllive.theiet.org/content/conferences/10.1049/cp.2011.0250
This paper presents a case study that applies ISO 26262 Part 3 to the hazard analysis of an inwheel electric motor. It describes the activities undertaken, their mapping onto the Standard, and discusses the limits and strengths of the analysis and possible alternative approaches. (8 pages)

A review of multi physics in machine design
http://dllive.theiet.org/content/conferences/10.1049/cp.2011.0028
The electromagnetic design of modern electrical machines nowadays requires more particular attention with respect to various parasitic effects or specifications which have to be fulfilled from the drive system. As in the past the electrical machine was considered as a component of a drive train, today's ideas concern an entire system including the individual properties and operation of the components. This inherently means that the development of a drive train clearly means to solve a multidisciplinary task on the system level. A modern drive system consists of the electrical motor, the power electronic converter and the associated controls. Therefore, the multiphysical system for an electrical drive train can be regarded as electromechanical, electric and controlcircuit coupling (Fig. 1). Next to the interaction of the drive system components itself, they need to be described, respectively modelled in a multi physical way as well. Inside the electromechanical energy converter, e.g. the motor, the magnetic field electrical circuit coupling have in the most simplest case to be considered. Particular problem classes with e.g. thermal couplings, mechanical forces acting on the energy converter exciting noise and the material models which simulate the ferromagnetic losses inside the device represent a multi physical task as well; this time on the detailed model level of the device (Fig.1). There are various possibilities to realise the mentioned couplings of the single physical effects. Numerical strong and weal coupled overall models can be derived and used to simulate either on the system level or on the detailed component level. The evaluation of multi physics solutions can be a troublesome task. The complicated interactions of the single problem types requires next to the algorithmic aspects of the solution process for the physical aspects novel approaches to evaluate the solution. The way of representing and postprocessing solutions in diagram form or coloured schemes is not sufficient to evaluate the increased number of parameters influencing the overall solution of the problem. A novel way to perform such an evaluation can be to employ techniques out of the field of virtual reality (Fig. 2). This approach enables not only to evaluate multi parameter models but as well is suited to interactively influence the design procedure for the device under study.

The development of an electromagnetic analytical design tool for megawattscale YASA generators
http://dllive.theiet.org/content/conferences/10.1049/cp.2011.0240
This paper presents the development of an analytical design tool for a megawattscale Yokeless And Segmented Armature (YASA) generator. This tool optimises the design of the machine to meet the user requirements, using least possible amount of active materials. The results of the analytical method are compared with those achieved by hand optimisation and on an existing 12 cores 10 poles YASA prototype machine to evaluate its validity. To investigate the feasibility of the YASA machine on wind turbine applications, the optimisation results of the YASA machine are compared with the RFPM machines and the AFPM machines under low power range (1 kW to 100 kW) and high power range (1 MW to 10MW). (6 pages)

Identification of model parameters for a direct drive permanent magnet wind generator
http://dllive.theiet.org/content/conferences/10.1049/cp.2011.0226
The increasing penetration of wind energy requires better understanding of its impact on power system stability and control. Modelling of permanent magnet wind generators has become increasingly important for power system studies. A simplified permanent magnet wind generator model is presented and used to show the different parameter identification strategies. By adding the logics and threshold settings to this simplified model, it can be shown that the model of permanent magnet wind generator will be improved. (5 pages)

Numerical modelling of an axial flux permanent magnet machine for convection heat transfer
http://dllive.theiet.org/content/conferences/10.1049/cp.2011.0165
This paper presents the thermal performance of NGenTec Axial Flux Permanent Magnet (AFPM) prototype generator operating at 100rpm through the thermal analysis on single stage. The CFD model coupled the heat transfer and fluid flow modelling provides good interpretation of the thermal behaviour of the test generator at steady state. In the comparison of two ventilation conditions, the CFD simulations show the temperature drop of 45°C same as what the experimental measurements obtained. (6 pages)

Field weakening control of pm generator used for small wind turbine application
http://dllive.theiet.org/content/conferences/10.1049/cp.2011.0174
Small wind turbines (in the range 250kW) harvest wind energy to provide carbon free energy for residential and small commercial applications and remote or developing economies. Current stateofthe art technologies generally utilize simple diode bridge rectification of the output from brushless permanent magnet (PM) generators and grid connection via DCDC converters and voltage source inverters. Such simplified systems do not utilize the full capacity of the generator, power conversion electronics and therefore the turbine due, in part, to inappropriate or simplified control but also generator overdesign for protection/safety reasons. This paper presents a different approach to the design procedure for a wind turbine generator drive system that actively controls the generator upto and above the system base speed imposed by the (electrical) supply voltage constraint. The paper demonstrates the impact of wind generator power characteristics over the annual energy production. In addition, it shows the reasons for field weakening control of a PM generator, that is verified experimentally using a market available system. (8 pages)

Superconducting generators for renewable energy applications
http://dllive.theiet.org/content/conferences/10.1049/cp.2011.0102
There is a trend toward higher power rated machines for offshore wind turbines. The maximum power rating for a highspeed, geared powertakeoff system is around 5MW. For even higher power rated turbines, directdrive generators becomes enormously heavy. Directdrive superconducting generators have the potential to reduce the overall mass and installation costs of an offshore wind turbine. In this study, a conventional homopolar superconducting generator design is presented that is suitable for lowspeed, hightorque directdrive applications. The generator has been designed with a stationary dcfield winding to increase the reliability of the generator. Also, a linear version of the generator is presented. (6 pages)