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Induction Machine (IM) fault detection techniques such as Fast Fourier Transform (FFT) which is a popular steady-state analysis method is recognized to be highly dependent on the IM loading and speed conditions. Nonetheless, implementing an FFT or even Short Time Fourier Transform (STFT) will result in low resolution frequency characteristics especially under a variable speed and loading conditions. Consequently, fault detection and classification under variable loading and speed conditions is quite inconvenient. Since, mechanical faults are one of the major breakdowns, which occur in IMs, it needs to be addressed to prevent breakage andfault extension. This paper investigates and detects faults under variable loading and speed conditions by studying the Motor Current Signature Analysis (MCSA) using a novel developed parallel technique based on the discrete wavelet transform (DWT).The proposed model input would be MCSA with the similar drive, loading condition and constraints for both healthy and faulty electric motors and the Discrete Wavelet Transform (DWT) is used as a detection technique. The proposed technique uses the DWT to the IM’s stator current to extract the desired features including Min, Max, Standard deviation, and Energy of the signal as a specific vector for each electric motor. In addition, different mechanical faults including Rotor broken bar(s), eccentricity and bearing have been detected using the proposed technique. Then, the accuracy of proposed parallel model using DWT is verified using experimental set-up of the parallel machines under variable loading and speed conditions for different mechanical faults. Finally the results of the proposed technique for all mechanical faults is tabulated and presented.

In the rapidly growing field of electrified transportation technology, hybrid electric and electric vehicle (HEV/EV) manufacturers have been placing increasing demands on the designers to improve the efficiency and reduce the costs of vehicle components to sustain a niche in the EV market. To understand the significance and challenges in an efficient and economical drivetrain design, this paper presents a part of an ongoing project that aims at developing a comprehensive study on dc/ac drive motor technology in EV applications. In this paper, a new three-level three-phase matrix converter topology, along with two conventional frequently used three-level three-phase dc/ac converter topologies, namely, diode-clamped and H-bridge converters, are implemented. Furthermore, comprehensive analysis and comparative studies are conducted to examine the performance and efficiency of these converter topologies according to EV design criteria. In addition, experimental investigations are carried out on the aforementioned converter configurations to help EV designers choose the most suitable converter topology.

The power utility companies have been trying to identify and locate three-phase transmission line faults in the shortest possible time in order to prevent economic losses. In the last few decades, technology used for power system protection has evolved from electromechanical devices to solid state and processor-based intelligent devices. This study presents the design and implementation of a wavelet analysis-based fault detection and identification module that contemplates the analysis of high frequency transients produced during faults. The design was implemented on a cost effective low-end embedded system. The proposed logic employs a multi-resolution wavelet analysis of high frequency details in the range of 5-10 kHz. The amount of high frequency components present in the transformed current signals, obtained after processing, identifies the fault. The ground and line-to-line faults were classified on the basis of the adaptive thresholds obtained from system behaviour. The proposed approach, after the completion of simulations, was implemented on a digital signal controller. The developed fault detection and identification prototype was successful in accurately identifying the power system faults, thus validating the feasibility of the proposed methodology.

This paper presents multiple methods for the design of a robust disturbance torque estimator. The benefit of these designs is that they ensure robust estimation in the presence of model uncertainties and/or noise. It is shown that these estimation schemes can be used to estimate both constant and nearly constant disturbance torques. In order to design the observers, the nominal plant model is expanded to incorporate uncertainties. Various cases for the design of the observer are presented. All of the cases are tested on a real system using varying degrees of model uncertainty to ensure that robust estimation is achieved. The results are validated using an in-line torque sensor and are presented accordingly.

This investigation presents optimal selection of Proportional Integral (PI) controller parameters for the speed control in Permanent Magnet Synchronous Motor (PMSM). Optimal selection of PI controller parameters is necessary to improve performance of PMSM. For this purpose, this investigation uses two evolutionary optimization algorithms namely, Real coded Genetic Algorithm (RGA) and Bio-geography Based Optimization (BBO) algorithm. In order to showcase the improvements obtained by PI controller tuned using RGA and BBO algorithms, their performances are compared with the conventional PI controller. Our results indicates that the PI controller tuned using BBO algorithm provides better transient and steady state performance for PMSM.

In this paper, an analytical torque ripple model for interior permanent magnet synchronous machine (IPMSM) is introduced at first, which can be used to estimate the torque ripple. Then, the inductance variation due to magnetic saturation is analyzed through experimental investigations, which demonstrates that magnetic saturation has a great influence on the inductances, and hence the torque ripple minimization performance. Thus, this paper proposes an online parameter identification approach to estimate the inductances and incorporates them into the torque ripple minimization. The proposed parameter identification approach can estimate the dq-axis inductances accurately such that it brings significant torque ripple minimization improvement for IPMSMs. Numerical and experimental investigations have been conducted to validate the proposed approach based on a laboratory IPMSM.

This manuscript presents an analytical model of eddy current losses in an interior permanent magnet motor (IPM) due to carrier frequency and harmonic current in maximum torque per ampere (MTPA) control operation. The influence of pulse width modulation (PWM) and motor design parameters has been considered to evaluate the increase in losses due to carrier harmonics based on PWM ripples and harmonic power loss derivations. The results are validated using a coupled 2-D FEA model and experimental tests conducted in a laboratory IPM.

In this paper, a novel 3-D sub-domain analytical model is developed to determine magnetic flux distribution in single-cage induction machines (IMs) with skewed rotor bars under no-load condition in an effort to more detailed analysis of spatial harmonics. The proposed model, along with an optimization algorithm, is as an alternative solution to finite-element analysis (FEA) in optimizing the geometry of IMs. The analytical method is based on the resolution of 3-D Laplace and Poisson's equations in cylindrical coordinates using the separation of variables method to calculate the magnetic vector potential for corresponding sub-domain. The proposed model includes the effect of slotting and tooth tips for the stator and rotor slots, which is usually neglected in a 2-D analysis due to the complexity of differential equations. Also, the proposed 3-D model can be used for any slot-pole combination in addition to considering the asymmetrical effect in the axial direction, which is a source of noise, vibration, and excessive losses in IMs. To evaluate the performance of the proposed 3-D analytical model, calculated magnetic-field distribution is compared with the results obtained from the 3-D FEA.

A stator winding fault in one phase of induction motor (IM) gives rise to higher harmonics distortion, increased torque ripple, temperature rise in the magnetic material, mechanical vibrations due to varying magnetic forces and magnetic noise. The fault leads to a change in the electromagnetic field generated in the motor as compared to the normal operation of motor. The copper losses generated in stator increases, thus leading to overall increase in the temperature of the motor. Looking from the aspect of electrical equivalent circuit model, the parameters of the motor changes due the occurrence of fault, which makes it difficult for designing a drive for the motor. In this paper a novel computational model has been presented which uses both artificial neural network model (ANN) and lumped parameter thermal network (LPTN) for parameter estimation and calculation of losses which can be used for designing a fault-tolerant, loss minimizing drive. This dual network model has been and experimented on a 7.5 hp aluminum-rotor induction motor.

The magnetic properties of non–oriented electrical steel (NOES) vary significantly with respect to the microstructure and crystallographic texture of the final steel sheets, which, in turn, are highly dependent upon the thermomechanical processing parameters used during hot rolling, cold rolling and annealing. This paper performs an exploratory performance analysis of NOES for use in high–speed traction motors, emphasizing the importance of obtaining an appropriate crystallographic texture to achieve the desired magnetic properties by controlling the annealing temperature and holding time. A 3.2% Si NOES annealed at 860°C for 24 hours after hot rolling can result in reduced core losses after cold rolling and final annealing. This material was chosen for the performance analysis of a laboratory scale high–speed, high–power traction motor (45 kW, 10,000 rpm) using finite element analysis (FEA). The motor using the NOES is compared to that using a commercially available grain–oriented electrical steel (GOES) to highlight the feasibility and advantages of NOES for high–speed motor applications. In addition, the motor performance using the NOES is compared to that using commercial NOES to understand the scope of improvement obtained by optimizing the microstructure and texture of the steel sheet.

This paper investigates aluminium and copper windings for a permanent magnet synchronous machine (PMSM) developed for direct–drive electric vehicle (EV) application. Previously, studies have been conducted on comparison of these windings in terms of thermal and electrical conductivity, cost and mass density. However, the impact of these windings on the machine’s performance in terms of efficiency and torque has not been analysed. In this paper, for the same machine volume and geometry, a comparative analysis of PMSMs with copper and aluminium windings has been performed in terms of efficiency, torque, weight, operating speed range, ohmic losses and temperatures. Furthermore, as these machines are developed for direct–drive EV application, drive–cycle-based analysis was conducted for urban and highway cycles for a 2013 Ford Focus vehicle dynamics model. For these drive cycles, analysis in terms of torque speed characteristics and maximum energy density efficiency for both the machines has been performed.

In this era of advanced computing where complex algorithms and expensive approaches are used to determine the machine parameters of a synchronous machine (SM), this paper proposes a novel, economical, and yet fundamental approach toward estimation of the d- and q-axis fields and damper circuit parameters of a low-/medium-power wound-field SM. The proposed novel methodology employs fundamental voltage, current, and flux linkage relationships of the three-phase wound-field SM in a-b-c reference frame theory. First, the proposed methodology has been explained in detail using analytical equations and then employed to determine the aforementioned parameters of a small laboratory SM. Other equivalent circuit parameters have been determined using conventional tests. Further validation of the proposed methodology was performed using two other larger machines with different nameplate ratings. Moreover, the aforementioned parameters of the larger machines were also experimentally determined using IEEE standard tests. Finally, a comparison of the results obtained employing the conventional and the proposed methodologies was performed, and the proposed methodology has been established to be valid as the results are in close agreement.

The concept of electrified vehicles (EVs) is the best old "new" idea that has been around for the last century. Designs have changed to make EVs popular, but until now, no design has captured the public's imagination or gained market traction. This is because consumers need more than facts about EVs; they need to be wooed into making a bigger commitment to the EV. The winning combination of making the EVs indispensable to the average North American consumer can be found in accessible charging infrastructures, reliable long-life batteries, and increased mileage. Vehicle manufacturers want a better-quality Ev to offer consumers to increase market penetration. Engineers and policy makers, to make this relationship a reality, need to appeal to more than just consumers' minds and go beyond testing and performance statistics and test results.

Performance of electrical machines is critically affected by the saturating nature of ferromagnetic materials. In order to have a reliable and accurate estimation of the steady-state behavior of synchronous machines, it is important to have a precise machine model that includes saturation. This paper aims to develop a new synchronous machine model incorporating an accurate saturation model. The algorithm used in this paper to represent magnetic saturation calculates the coefficients in several real function expressions for the saturation characteristics of a synchronous machine. The new synchronous machine model proposed in this paper has been used in the investigations to calculate the machine behavior in various operating conditions.

First, exclusive investigations are performed in this paper on a developed prototype of an axial flux switched reluctance machine to elicit the issues of low inductance ratio due to higher leakage flux in this type of machine. Thereafter, three different novel approaches based on a special winding configuration, segmented grain-oriented steel core and magnetic shielding are proposed to mitigate the leakage flux. These approaches are then tested individually using 3-D FEA. In addition, comparative performance analysis of the original machine model and the machine with each of these approaches is carried out.

Understanding the importance of saturation of parameters in line-start permanent magnet synchronous machine (LSPMSM) and the scanty available research literature on simplistic methods of determining the magnetizing characteristics of LSPMSM, this paper proposes a novel and yet simplistic approach towards its determination. Experimental investigations have been performed on a laboratory LSPMSM based on the proposed dq axis (two-axis)-based methodology and the measured magnetization characteristics of the machine has been incorporated into the machine model. The measured characteristics have hence been validated through dynamic and steady state performance analyses of the machine under direct online (DOL) starting. Furthermore, performance analysis of the machine has also been performed through the developed machine model with and without incorporating the magnetization characteristics of the machine to elicit the effects of parameter saturation during startup and synchronization of the machine.

Inaccuracy in the permanent magnet synchronous motor (PMSM) steady-state performance calculation corresponds to the parameter error and model imprecision. Accurate determination of the PMSM parameters may encounter various complications because of its rotor structure and drive design. Therefore PMSM performance calculation is generally vulnerable to inaccuracy because of the parameter error. This article studies the effect of parameter error on the inaccuracy of the performance calculations. Several methods for determining the PMSM armature resistance, flux linkage constant and d- and q-axis inductances with varying level of accuracy are proposed. The presented methods are applied to a laboratory PMSM and the sensitivity of the PMSM output power to the equivalent circuit parameters is analysed based on the experimental results. In addition, this study contributes to accurate performance estimations of the PMSM by developing a precise model that incorporates the saturation saliency and core losses. The accuracy of the proposed model is compared with the conventional dq-axis model and its higher accuracy is validated through experimental results.

This paper presents challenges in an ongoing project related to the design of a premium efficiency three-phase line start permanent magnet synchronous motor (LSPMSM) and proposes an exclusive solution through development of a novel magnetic circuit model. Since the LSPMSM is rapidly replacing the conventional induction motors in industrial applications such as pumps, fans and conveyors which require the machine to operate under both frequent start-stop and steady-state conditions for a wide range of time, a trade-off has to be reached between their starting performance and efficiency post-synchronization. Until now this has only been possible with time consuming FEA based design methodology. Hence, understanding the need and scanty availability of literature on simplistic and yet precise magnetic circuit based design of three-phase LSPMSM, this manuscript proposes exclusively a novel magnetic circuit model to design LSPMSM with improved starting performance. Firstly, the aforementioned design issues have been illustrated using different machine configurations developed. Further, a detailed procedure to deal with the design issues with the help of the developed magnetic circuit model is discussed and validated by developing a machine where the trade-off has been reached.

Switched reluctance motors (SRMs) show crucial attributes to applications where light weight, high-temperature adaptability, fault-tolerance capability, ruggedness, and simplicity are strongly required. The axial-flux configuration of SRM has additional features over the radial-flux configuration. This paper presents the design and analysis of a novel axial-flux SRM. Detailed procedures of deriving the output power equation as a function of the motor dimensions and parameters are provided. A modified phase winding design approach is thoroughly explained, a flowchart describing the design algorithm is presented, and the inductance determination by different methods is verified experimentally. The 3-D finite-element analysis (FEA) unveils the excessive end core and radial-flux fringing effects in the axial-flux configuration. An exclusive pole-shape design is also proposed. The operation of the motion model using 3-D dynamic FEA is analyzed, and its prototype development process and static testing are demonstrated.

As Canada and the world move rapidly toward increased reliance on wind power generation, self-excited induction generators (SEIGs) will play an important role in distributed wind power generation (DWPG). Understanding the significance and prospects of SEIGs in DWPG, first, this paper elucidates the significance of fault detection (FD) and voltage regulation (VR) in the aforementioned application. A comprehensive analysis of VR and faults on niche industrial 7.5-hp copper-rotor SEIG and conventional 7.5-hp aluminum-rotor SEIG is performed through numerical simulations, and the calculated results are validated through experimental investigations. Second, a twofold Daubechies-wavelet-transform-based module is designed for the following: 1) FD and 2) VR, respectively. A discrete-wavelet-transform-based algorithm is proposed and implemented on a low-cost embedded system to provide an economical solution for the aforementioned issues. Thereafter, the aforementioned schemes are tested, and results are investigated.

Understanding the need for improvement in monitoring and protection in high performance charging technology for a growing demand of EVs/PHEVs, this research manuscript presents a part of an ongoing project and proposes a novel low cost dual purpose triangular neural network based module for power quality monitoring and protection (M&P) and elicits its performance in times of abnormalities or malfunction in a high performance off-board level 3 bi-directional charger for electric vehicles. Firstly, design and implementation of the low cost dual purpose triangular neural network based device for monitoring the power quality and hence, protecting the grid has been explained and its performance has been presented through numerical investigations. Going a step further, the device has also been experimentally tested using an in-house electric vehicle containing a commercially available battery charger and the measured results are analyzed. Secondly, a high-performance vector-controlled bi-directional off-board level-3 charger for faster and efficient charging has been developed and investigations have been performed on the healthy charger to analyze its performance. The primary aim of developing this charger was to elicit the usage and performance of the previously developed M&P device to protect the grid in case of some typical charger malfunction problem in such a charger, which is not detectable by conventional low cost sensors employed with such chargers. Once the module detects any abnormalities in the charger's operation, information gathered can be used to tune the controller in the charger to obtain a constant improved performance of the charger or the power transfer can be terminated.

Understanding the importance and the scanty availability of research literature on parameter estimation of line-start permanent magnet synchronous machine (LSPMSM), this paper proposes a novel and yet fundamental approach towards parameter estimation. Experiments have been performed on a laboratory LSPMSM based on the proposed dq axis methodology and measurements have been validated by analyzing the performance of the machine under different conditions using a developed computer program and an experimental setup. Dynamic and steady state performance analyses have been subsequently performed using the determined parameters and the results have been presented under direct online (DOL) starting and a sudden increase in load torque.

Direct-drive electric vehicle motors have requirements such as high-torque, low-speed and a constant power speed range (CPSR) between 3 and 5 depending on the tire size. Furthermore, these motors must deliver lower cogging torque and torque ripple when compared to conventional electric vehicle high-speed motors due to absence of any damping mechanism. Surface permanent magnet synchronous machines (SPMSMs) with distributed winding configuration are found to favor the aforementioned characteristics for the above application. However, in spite of the lower CPSR requirements for direct-drive application, SPMSMs suffer from poor flux weakening operation. Various rotor structural modifications as well as optimal PM sizing solutions are proposed in literature. However, they fail to take into account the stator slotting effect which significantly affects the flux weakening operation of the machine. Thus, in order to alleviate the challenges involved in realizing a SPMSM as a direct-drive motor, Response Surface Methodology (RSM) is implemented with magnet size and stator slot dimensions as design variables in an effort to optimize the characteristic current and further enhance the CPSR of the machine. Finite element models of the optimal machine are used to verify the output power- and torque-speed characteristics over entire operating range calculated from analytical equations.

The spatial harmonic of magnet flux is a major cause of torque ripple in permanent magnet synchronous machines (PMSMs), and it is temperature-dependent. Thus, this paper investigates torque ripple modeling and minimization for PMSMs considering magnet temperature variations. Firstly, experimental studies are conducted to demonstrate that the torque ripple is magnet temperature dependent. Then, based on extensive experimental tests, a novel linear model is proposed to model the relationship between the dc and harmonic components of magnet flux in the dq reference frame, which provides a way to estimate the magnet flux harmonic. Based on this model, the torque ripple model considering magnet temperature variation is proposed and validated with simulations. Afterwards, a novel adaptive current optimization approach is proposed for torque ripple minimization, which consists of two parts: the magnet flux harmonics estimation using the proposed linear magnet flux model, and the current optimization using the proposed torque ripple model. In our approach, the stator current is adaptively optimized with respect to the magnet temperature. However, the proposed approach is not necessary to run in real-time, because temperature variation has a large time constant. Our approach is validated through both numerical and experimental studies.

An induction machine with skewed rotor bars has enhanced starting performance and reduced current harmonic distortion. In a conventional skewed induction machine (IM) modeling, the axial magnetic flux variation is usually ignored in machine performance analysis in spite of significant parameter variation in the axial direction. Furthermore, the selection of optimal skew angle is vital to keep the output torque constant, especially in electric vehicle applications. In this paper, a 7.5 hp IM with one slot pitch skew angle is considered as an initial model and space harmonic reduction has been investigated by considering axial variation of the air-gap flux density. An analytical model incorporating spatial harmonics due to slotting has been implemented in parallel with a 3-D FEA model towards improvements in skew angle and rotor bar geometry selection using improved swarm intelligence technique. The air gap flux density distortion and torque ripple due to space harmonic reduction for improved design are compared with that of the initial design.

This paper investigates the torque ripple modeling and minimization for interior permanent magnet synchronous machine (PMSM). At first, a novel torque ripple model is proposed. In this model, both spatial harmonics of magnet flux linkage and current time harmonics induced by machine drive are considered, which includes the torque ripples resulted from magnet torque, reluctance torque and cogging torque. Based on the proposed model, a novel genetic algorithm (GA) based dq-axis harmonic currents optimization approach is proposed for torque ripple minimization. In this approach, the GA is applied to optimize both the magnitude and phase of the harmonic currents to achieve the objectives of: 1) minimizing the peak-to-peak torque ripple; 2) minimizing the sum of squares of the harmonic currents; and 3) maximizing the average torque component produced by the injected harmonic currents. The results demonstrate that the magnitude of the harmonic current can be significantly reduced by considering the phase angles of these harmonic currents as the optimization parameters. This leads to further suppression of the torque ripple when compared to that of a case where phase angles are not considered in the optimization. Also, an increase of the average torque is achieved when the optimum harmonic currents are injected. The proposed model and approach are evaluated with both numerical and experimental investigations on a laboratory interior PMSM.

Surface Permanent Magnet (SPM) synchronous machines with fractional slot concentrated windings (FSCW) have been found to provide high torque density with low torque ripple and cogging torque, making them suitable for direct-drive electric vehicle (EV) application. This paper initially analyses a 3-phase 36/30 FSCW SPM machine for direct-drive application in terms of its space harmonics, steady-state characteristics and losses over a wide speed range using winding function theory and MTPA control in conjunction with finite element analysis (FEA). It was found that the 3-phase machine produces high space harmonics in the flux density which resulted in increased magnet eddy current loss and high stator leakage inductance which leads to extended constant power speed range (CPSR) as well. Since, the CPSR requirement for a direct-drive EV motor is lesser than that of a high-speed EV motor, there is scope for reducing the stator leakage inductance. Hence, a 6-phase 36/30 FSCW SPM machine employing the same stator, rotor and current rating as that of the 3-phase machine is investigated in an effort to reduce space harmonics, stator leakage inductance and magnet eddy current losses while delivering the desired output characteristics. Also, an analytical method to calculate the 6-phase machine d- and q-axis inductances from winding and slot permeance functions are proposed. Thereafter, a comparative performance analysis is conducted on both the 3-phase and 6-phase machines designed and results are discussed.

Removal of the gear-box from a conventional all-electric vehicle (EV) power-train and incorporating direct-drive topology is expected to improve motor-to-wheel efficiency. Firstly, this paper discusses the merits and challenges of a novel direct-drive scheme employing a single on-board motor in an EV. Thereafter, motor design targets established for such an application in a typical super-mini EV are discussed. A novel bottom-up approach based on maximum-torque-per-ampere (MTPA) control and winding function theories of PM machines is proposed to design an on-board direct-drive surface permanent magnet (PM) machine with fractional-slot concentrated-windings in the stator. A typical direct-drive motor is designed employing the proposed approach and its performance is analyzed using its electromagnetic model in conjunction with finite element analysis and MTPA control scheme over the entire speed range of the motor. Comparative analysis of results obtained from analytical calculations and finite element analysis is performed. It is also shown that the proposed direct-drive scheme in EV is worth considering for advancement of state-of-the-art EV drive-train systems technology.

Understanding the significance of precise torque control of electrical machines and the importance of accurate motor parameter determination to achieve the control precisely, this manuscript proposes a new method of identifying varying parameters of permanent magnet synchronous machines through a two-step on-line estimation algorithm incorporating iron losses. An improved machine model incorporating iron losses has been developed to identify on-line, the inductances, permanent magnet flux linkage and stator resistance as a function of operating temperature. The effect of iron losses on the accuracy of estimation of machine parameters has been studied under varying operating conditions and the performance has been compared with conventional estimation without iron losses. The developed identification technique improves the precision of online estimation and can be applied towards maximum efficiency or adaptive control of PMSM. The mathematical model and experimental results have been presented for validation.

The state of health (SOH) of batteries in electric vehicles (EVs) results in the powertrain performance of EVs. However, to predicate the accurate SOH become a challenge due to the complicated factors, such as open circuit voltage, current, temperature, state of charge (SOC), internal resistance and the combination which affect the battery SOH. It is of primary importance that the SOH can be predicted on-line and real-time. This paper proposes a novel SOH prediction method based on Grey-Markov Chain (GMC) to determine the battery health state by taking into account the battery internal resistance. A real-time battery internal resistance monitor device is designed and applied in experimental. The results show that the proposed GMC model is effective and efficient in estimating SOH for LiFePO4 Power Battery.

Due to the advantages of higher efficiency, low manufacturing cost and lower machine weight, Copper Rotor Induction Motor (CRIM) is a suitable cost effective alternative choice over permanent magnet motor in EV/HEV traction applications [1]. However, temperature rise issue is a critical factor that has direct effects on machine parameters such as effective resistances and inductances as well as magnetic properties of the machine materials. In this paper, a lumped parameter thermal network (LPTN) model is proposed to predict transient thermal behaviour in a Totally Enclosed Fan Cooled (TEFC) CRIM considering non-existent of forced convection heat transfer in stator end-winding due to smooth rotor geometry. The model also takes into consideration of various losses as heat sources that are determined from motor loading experiments. In order to validate thermal model, a 20-hp CRIM is tested under varying speed and loading conditions to measure the actual operating temperature rise and compared with calculated temperature rise.

Removal of the gear-box from an existing electric vehicle (EV) power-train incorporating direct-drive topology is expected to improve motor-to-wheel efficiency. Firstly, this paper discusses the need for a novel direct-drive scheme employing a single on-board motor in an EV. Electric machine and drive design targets for such a supermini EV with direct-drive scheme are fixed based on analytical equations, benchmark data obtained from commercially available EV motors, drives, transmissions and literature study. Employing a comprehensive vehicle dynamics model of the supermini EV, machine design targets previously fixed are further refined to yield desired dynamic and steady-state performance of the EV over an urban drive cycle. An on-board direct-drive surface permanent magnet synchronous machine with fractional slot concentrated windings in the stator is designed. The machine's performance is then analyzed using its electromagnetic model in conjunction with maximum-torque-per-ampere control scheme over the entire speed range of the motor. Results from finite element analysis are discussed in detail to show that that the proposed direct-drive scheme in EV is worth studying and the machine designed can be improved in order to obtain efficiency improvement in an EV drivetrain system and hence extend the driving range of EV.

Self-excited induction generators (SEIGs) will play an important role in off-grid wind power generation. To advance understanding of the significance and prospects of SEIGs, this paper elucidates the significance of incorporating the proximity effect in the conventional model of self-excited induction generators. The researchers offer an analytical model to incorporate the proximity effect in the rectangular rotor bars of the SEIG. The model’s accuracy relies on a computer program. The calculated results are experimentally verified in the case of two 7.5 hp aluminium- and copper-rotor SEIGs under open-circuit and static loading conditions, through an exclusive qualitative analysis of terminal voltage build-up at no-load, variation in terminal voltage and frequency, as a function of the proximity effect. The paper examines also the voltage regulation, frequency regulation and excitation capacitance requirements of both aluminium- and copper-rotor SEIGs.

Wind is one of the most efficient renewable energy sources available. Wound-rotor induction generators, specifically the doubly-fed induction generator, have numerous advantages in wind power generation in comparison to other generators. Doubly-fed induction generators use a converter cascade between the slip-ring terminals and the utility grid to control the rotor power. A vector control scheme developed to control the rotor side voltage-source converter allows independent control of the generated active and reactive power, as well as the rotor speed in accordance with the maximum power point. This paper proposes two different schemes by which the vector controller can fine-tune its proportional and integral gains. The first scheme is a self-adjusting gain scheduler, which uses different characteristics such as linear, exponential, etc. to generate a variation in the proportional and the integral gains. The second scheme is a fuzzy logic gain scheduler. The paper analyses and compares the transient respo...

This paper addresses the performance and reliability issues as encountered by the present EV technology. The research work presented in this paper is based on an ongoing project which has a twofold research motivation: 1) use of wavelet analysis to determine transients in electric vehicles; and 2) application the information obtained during transient detection to address the performance and reliability concerns. The novel wavelet based transient detection unit designed and developed as part of this project is discussed in this paper. The prototype is developed on a low-cost embedded system in order to provide an economical solution. Significance of the developed transient detection unit is also illustrated in this paper by developing applications that ensure a robust and reliable drivetrain with enhanced performance. Firstly, the information gathered from the transient detection unit is used to determine in-vehicle electrical faults. Secondly, this transient detector is used to facilitate the optimization of hybrid energy storage system (battery/ultra-capacitor combination) and to ensure smooth battery operation.

Saturation in the ferromagnetic core significantly affects the performance of electrical machines. In the performance analysis of electrical machines, an accurate representation of the saturation characteristics in the machine model is important. In this paper, a new trigonometric algorithm is proposed to represent the saturation characteristics of electrical machines based on the measured saturation characteristics data points. This model can be applied to various kinds and sizes of electrical machines. The calculated results demonstrate the effectiveness of the proposed model. This trigonometric model has been applied to a conventional synchronous machine model and extensive stability performance analysis has been carried out. This further reveals the usefulness of the proposed trigonometric saturation model and the importance of the inclusion of saturation in stability analysis.

This paper presents a method for the design of a robust disturbance torque estimator. The benefit of this design is that it ensures robust estimation in the presence of model uncertainties while maximizing the sensitivity of the estimation to the disturbance torque. It is shown that this estimation scheme can be used to estimate both constant and nearly constant disturbance torques. In order to design the observers, the nominal plant model is expanded to incorporate uncertainties. Various cases for the design of the estimator are presented. All of the cases are tested with varying degrees of model uncertainty to ensure that robust estimation is achieved.

Wound-rotor induction generators have numerous advantages in wind power generation over other types of generators. One scheme is realized when a converter cascade is used between the slip-ring terminals and the utility grid to control the rotor power. This configuration is called the doubly-fed induction generator (DFIG). In this paper, a vector control scheme is developed to control the rotor side voltage source converter that allows independent control of the generated active and reactive power as well as the rotor speed to track the maximum wind power point. A neuro-fuzzy gain tuner is proposed to control the DFIG. The input for each neuro-fuzzy system is the error value of generator speed, active or reactive power. The choice of only one input to the system simplifies the design. Experimental investigations have also been conducted on a laboratory DFIG to verify the calculated results.

PurposeIn order to assess the performance of an induction generator in standalone wind power application, it is imperative that mathematical models are developed that accurately represent the system and take into account various electromagnetic influences such as skin effect. The purpose of this paper is to utilize mathematical models to study the transient and steady‐state behaviour of the self‐excited induction generator (SEIG), in one case with an aluminum rotor, in another case, with a copper rotor, under various load conditions while taking the above factor into account.Design/methodology/approachMathematical models of a SEIG in the d‐q axis frame have been developed based on the generalized machine theory. A relationship between the mutual inductance and the magnetizing current of the machine has been presented. The rotor impedances have been customized to include skin effect. Using these relations, the model has been extended to include the saturation and skin effects. In order to verify the accuracy of the models, numerical and experimental investigations have been carried out on two 7.5 hp aluminum‐rotor and copper‐rotor SEIGs.FindingsIt was found that the model that takes into account the saturation and skin effects produces numerical results that closely match experimental values for both the machines.Originality/valueThis paper describes how a model of an SEIG considering saturation and skin effect has been developed and applied to aluminum‐ and copper‐rotor machines of similar power ratings to analyze their performance.

The beneficial nature of employing power electronics and drive components in conventional electric vehicle (EV) towards level 3 charging capability has propelled research activities towards integrated charging (IC) technology. However, alternating magnetic fields produced in the air-gap by AC charging currents and the stationary nature of the rotor leads to unusual loss and magnet operating characteristics. Since the same permanent magnet synchronous motor (PMSM) will be used for both traction and IC, it is important to understand the machine's behaviour during IC to optimally design the machine for both applications. Hence, this paper exclusively investigates: 1) permanent magnet operation; 2) electrical and magnet losses; 3) temperature rise; and 4) effect of winding inductances on voltages and currents, in both surface and interior traction PMSMs employed for IC in EVs. Results obtained from investigations conducted on laboratory interior and surface PMSMs using finite element analysis and experimentation are analysed and discussed.

Recent progress in wind-power generation has led to the use of grid-connected and self-excited induction generators (SEIGs). Aluminum has been the common conductor material for squirrel-cage induction machines for a long time, largely because of low cost and ease of manufacturing. Recent developments in materials engineering have brought forth copper-rotor induction machines with promising results. In these machines, skin effect as well as temperature effect on the machine equivalent-circuit parameters during operation are expected to play an important role in the evaluation of induction-machine performance. In this paper, a qualitative performance analysis of aluminum- and copper-rotor SEIGs considering the skin and thermal effects has been presented theoretically and experimentally.

A new method of representing magnetic saturation in synchronous reluctance generator has been proposed in this paper. A linearized model of synchronous reluctance generator has been developed applying the proposed saturation model to perform the steady-state stability analysis. The effect of - and -axis saturation on the steady-state stability of a synchronous reluctance generator has been investigated using the proposed linearized machine model. Effects of different loading conditions such as active power, reactive power, and power factor on the steady-state stability have also been looked into. Moreover, the effect of - and -axis saturation on the transient stability analysis has been investigated in the case of a three-phase symmetrical ground fault at the machine terminals.

The prediction of induction machine performance has traditionally been based on the constant parameter models. This approach was later replaced by considering saturation in the main flux paths. However, such models have not been sufficiently accurate for certain transient conditions such as on-line starting and short-circuit. So, an accurate study of their performance should necessarily consider the magnetic saturation effect both in the main and leakage flux paths. In this paper, an experimental procedure to determine the machine parameters and saturation characteristics is adopted. The adopted experimental procedure facilitates the measurement of both stator and rotor leakage reactance saturation characteristics. Two models of saturated induction motors are developed to predict the transient performance of a laboratory wound-rotor induction motor. The results calculated by the proposed models considering and ignoring the leakage flux saturation are compared with the experimental results. The model that considers saturation in the leakage flux paths produces more accurate transient responses.

Idling the engine of heavy‐duty truck is the only way a driver can control the temperature in the cab/sleeper and have power for auxiliary devices when the truck is parked. It is an inefficient and noisy process that wastes thousands of litres of fuel per year while standing stationary in a parking lot. Almost all heavy‐duty trucks idle about 20–40% of the time when the engine is running, depending on season, geographic location and trucking operation. This extensive engine idling has many disadvantages, including pollutant emissions, noise pollution, unnecessary fuel and maintenance costs, and driver discomfort. This paper discusses the problems related to truck idling and proposes an auxiliary power generation unit that can significantly reduce the fuel consumption, cut the costs, enhance engine life and reduce pollution. A control methodology is presented to regulate the output voltage of the auxiliary power unit under variable load conditions.

Doubly-fed induction generators are gaining more attention especially in the field of wind power generation due to their many advantages and the rapid development in both power electronics and control strategies. In this paper, a new saturated doubly-fed induction generator model is proposed. This model takes into account both main flux saturation and leakage flux saturation. The effect of the main flux saturation and the leakage flux saturation on the determination of the transient performances of doubly-fed induction generator under different transient conditions such as step change in input power, voltage sag and short-circuit at the terminals is the main objective of this paper. It has been demonstrated that although the inclusion of the main flux saturation in the generator modelling is important, the effect of the leakage flux saturation is the most dominant in the determination of the transient performances in the first few cycles following the transient.

The mutual inductance, M, is a key figure of merit in all magnetically coupled systems, but it plays an especially crucial role in the design of loosely coupled coils used in inductive power transfer (IPT) systems. This paper presents a new closed form expression for the mutual inductance of planar circular spiral coils also known as Archimedean coils. This new expression, which is derived using the magnetic vector potential, accounts for both coil-to-coil separation and axial misalignment distances. In what follows, the analytical formulation is first presented. Next, MATLAB is used to evaluate the resulting expression over a wide range of separation and misalignment distances and corresponding plots are obtained. Finally, a physical prototype is built, tested, and its measured mutual inductance is compared against the previously obtained analytical results.

The percentage of copper losses in the induction machine (IM) governs the performance and hence the efficiency of the machine. The temperature dependence of stator resistance results in inaccurate performance prediction if temperature is not taken into account in advance. Hence, it is imperative to determine the relationship between temperature and stator resistance. This research paper investigates the change in stator resistance with increase in temperature over a period of time. An improved particle swarm optimization based scheme is developed for the estimation of stator resistance with the help of the two-axis model of induction machine, taking into account the temperature effect on the resistance. Further, a 15 kW copper-rotor IM has been tested using a PLC based drive system and the increase in temperature is measured using resistance temperature detectors to obtain online stator resistance. A comparative analysis of the experimentally measured stator resistance with that obtained from the numerical investigation of the temperature based two-axis model has been performed.

Understanding the significance of precise dynamic modeling of electrical machines and the importance of parameter determination for the same, this manuscript proposes a new method of identifying variable inductances and damper parameters of a line-start interior permanent magnet synchronous machine (LSIPMSM) through an off-line improved particle swarm optimization (IPSO). An improved dynamic machine model incorporating the dependence of inductances on magnetizing currents has been developed. Through the combination of experimental test methods conducted on the inverter connected LSIPMSM under varied operating conditions and IPSO algorithm, parameters such as stator and magnetizing inductances and damper parameters have been identified for all conditions. Though conducted on LSIPMSM, the modeling and identification procedures presented in this paper are also applicable to IPMSM and surface magnet PSM with simplified variations. Comparison results of experiments with conventional and improved models are also presented for validation.

The concept of integrated battery charger is attracting attentions these days. To design a motor drive system with an integrated charging capability, the machine windings are usually reconfigured to be used as the AC side inductors. Along with the switches from the drive circuitry, the AC side inductors form the voltage front-end to improve the power factor while charging. Most of the research work that was conducted was focused on the circuit topologies [1], [2] and the charger performances [3]. When looking into the basis, what will happen inside the machine when AC current is flowing through the machine windings? More specifically, the interactions between the electromagnetic field produced by the AC current excitation and the rotor magnetic field can cause electromagnetic torque and variations of the effective winding inductance. In this investigation, these two aspects, the produced torque and the impedance due to different winding configurations under a single-phase integrated charging operation employing a surface-mounted permanent magnet synchronous machine (SPMSM) drive system are analyzed. Experimental tests were conducted on a 21 HP, 8-pole SPMSM to verify the results.