Search

Early design stages of modern Switched Reluctance Machines (SRMs) are well-known for demanding the analysis of thousands of candidates. The need for reducing the computation time is, in turn, fostering the interest in design-oriented analytical approaches capable to maintain sufficient accuracy for SRMs featuring different geometries and rated operating conditions. To this end, this work proposes a novel design-oriented analytical model that predicts the flux linkage loci, i.e., a set of curves expressing the phase flux linkage as a function of both phase current and rotor position, from which the main performance are attained. The model comprises two main parts, each of them containing a novel scientific contribution: 1) a new interpolation technique for the flux loci based on second-order Fröhlich-Kennelly equations, and 2) an analytical model that caters for the flux linkage in partial overlap and saturated core conditions. Finally, the model is validated against Finite Element results of four SRMs, along with the experimental results of one of them, and its implementation in a design routine is discussed.

In the design of modern, high-performance switched reluctance machines, the highly restrictive sets of constraints and requirements severely limit the number of feasible solutions. In order to improve the chances of attaining a successful design, this work proposes a novel and fully analytical approach to the preliminary design analysis. Initially, the correct number of independent design variables is identified. Subsequently, constraints and requirements are introduced one by one, in order to progressively discard all of the unfeasible candidates. At the end of this process, the actual design space is attained, whose main characteristic is to be populated only by feasible candidates. A design case study shows how the proposed methodology allows: 1) to verify the design feasibility; 2) to reduce the number of candidates by orders of magnitude; and 3) to gain useful insight into the design problem and thus select the most convenient strategy to finalize it. As a result, a highly effective design process is attained, so that considerable computational resources can be saved.

Permanent Magnet Machines are widespread in the automotive industry, thanks to their high torque density and high efficiency. In automotive applications such as, for example, integrated starter alternators, a very wide Constant Power Speed Range is also required, for electricity generation on-board. To maintain a constant voltage, flux weakening must be employed during generation. With the conventional Electrical Flux Weakening methods, considerable amounts of current would have to be consumed to weaken the strong flux linkage from the magnets, which results on an efficiency decrease. Conversely, mechanical methods adjust the linked flux by manipulating the position of certain machine parts, avoiding the consumption of current. Thus, Mechanical Flux Weakening might be more suitable for the automotive applications, where a very wide Constant Power Speed Range is required, while preserving high levels of motoring torque capabilities. In the present Literature Review, various implementations of Mechanical Flux Weakening, from several authors, are analyzed and compared. The aim is to gain insight on the effectiveness of this method, in comparison with the electrical one, on fulfilling the mentioned automotive requirements.

The use of printed circuit board stators in coreless axial flux permanent magnet machines allows to reduce manufacturing costs and to eliminate the main drawbacks of traditional implementations using Litz wire. This work investigates the design of a coreless axial flux permanent magnet machine having printed circuit board concentrated windings. The field model of the coreless machine is reviewed to obtain closed-form equations for torque, eddy current loss and circulating currents loss are presented. Furthermore, cardinal geometrical parameters of the printed circuit board stator and the latest manufacturing possibilities are investigated, followed by the presentation of important machine design details.

The aim of this paper is to provide a simple and effective tool to determine the minimum resolution required from a rotor position sensor for variable frequency drives using fixed-position-based speed estimation. It is shown that it is possible to determine the minimum resolution based on the required bandwidth and phase margin of the speed control at the lowest operating speed. The effectiveness of the proposed method is then verified by means of dynamic stiffness analysis, performed in simulations and experimentally on a 3.6kW permanent magnet motor drive.

In high power density applications, such as electric or hybrid electric vehicles, heat extraction is a crucial aspect of electrical machine design due to stringent volume specifications. In these cases, it is extremely difficult, if at all possible, to satisfy the maximum temperature requirement when using conventional cooling systems, such as housing fins, shaft-mounted fans or even water jackets. To this end, a novel direct oil cooling system conceived for Torus-type axial-flux permanent-magnet machines is proposed here. In order to demonstrate its effectiveness, lumped thermal equivalent circuit simulations, finite element analyses and experimental tests are presented. The expected performances of the machine using the proposed direct oil cooling are compared to those obtained using state of the art water cooling.

Unmanned aerial vehicles are characterized by a set of requirements, like high efficiency, resiliency, and reliability that conflict with the other main requirement of high power density aimed at minimizing the overall weight and size. This article proposes a novel, modular multiphase drive for a quadrotor drone, realized through the integration of an axial flux permanent magnet machine and a GaN-based power electronic converter. After an overview of the design process, starting from the propeller choice, a brief description of the system components is presented. Focusing specifically on the power electronic converter, the article then presents a full analysis of its electrical and thermal performance. Extensive experimental tests allows to validate the predictions of the design and simulation stages and demonstrated the expected high power density levels.

In a bid to respond to the challenges being faced in the installation of flywheel-based electric energy storage systems (EESSs) in customer-side facilities, namely high safety, high energy/power densities and low cost, research work towards the development of a novel, one-body, laminated-rotor flywheel, based on a switched reluctance machine (OBOLAR-Fly SR machine) is presented, where the laminated rotor provides both the energy storage and motor/generator functions. The one-body architecture improves compactness and robustness. Besides, the rotor&rsquo, s laminated body ensures inherently high safety. From the design perspective, the rotor&rsquo, s dual purpose causes the traditional electrical machines design aspects, such as power development, cooling, losses, torque ripple, etc., to clash with the typical requirements of a flywheel, namely in-vacuum operation and moment of inertia. This results in six main trade-offs to be addressed during the design process: rotor material, speed ratio, number of drive phases, split ratio, optimal vacuum level, and controller hysteresis band. A 60 kW, 2.2 kWh OBOLAR-Fly SR system is developed with a twofold objective: (1) provide an in-depth description of the six bespoke design trade-offs and give some useful guidelines to tackle them, (2) prove the OBOLAR-Fly concept and compare the prototype&rsquo, s performance with the current state of the art flywheels. Preliminary experimental results prove the viability of the OBOLAR idea and show its competitiveness in terms of efficiency and power density. On the other hand, a gap in energy density to be filled in future research works is highlighted.

Thanks to the development in fields of materials and power electronics, the use of high speed electrical machines has boosted significantly in recent decades due to their many advantages and applications. To enhance this king of machines, it is absolutely necessary to reduce losses. This is especially applicable to eddy current losses. Their evaluation in the cooling sleeve of a toroidal high speed permanent magnet machine in this paper has been performed through 2D analytical harmonic model implemented in Matlab, 2D FEM model implemented in Cedrat Flux software and laboratory tests. The final goals have been to obtain a validated model to estimate eddy current losses and determine experimentally if the segregation of losses method is applicable to the considered problem. Two different materials, copper and aluminum, have been analyzed changing their thickness and varying the airgap between the external part of stator coils and cooling sleeve. The results show how electrical conductivity, frequency and geometry influence eddy current losses.

Common self-sensing methods for permanent magnet machine drives are critically eyed in automotive applications, due to audible noise, high computational effort or insufficient performance from point-of-view of functional safety. This work presents a saliency-tracking technique for zero and low speed based on square wave signal injection that is used in combination with a slowly sampled current control and a modified pulse pattern to simplify the necessary signal processing and increase injection frequency. Improvements in reducing the computational load, shifting the injection frequency out of the audible range and providing high bandwidth advocate the proposed method for a position-sensorless control system. The proposed method is enhanced with a back electromotive force (BEMF) based position estimator for intermediate and high operating speeds for being applied to an electric power steering (EPS) drive application as a software-based redundancy concept. Experimental results verify robust and reliable sensor monitoring and sensor fault-compensation. Safe operation is shown to be ensured in case of a position sensor-fault, even during safety-relevant manoeuvres.

A critical aspect of distributed generation systems focuses on the installation of Electrical Energy Storage Systems in customer-side facilities. In this scenario, flywheel technology is challenged to provide high levels of safety, compactness and competitive cost. This work presents a novel, one-body flywheel scheme based on a switched reluctance machine, whose laminated rotor fulfils both the motor/generator and energy storage functions. The one-body architecture enhances compactness and robustness, whereas the laminated rotor ensures high safety. The design of this flywheel scheme is characterised by a widely different set of trade-offs compared to conventional schemes. In order to prove the feasibility of the proposed scheme and to highlight its design trade-offs, a 60kW, 2.2kWh one-body flywheel is presented as a case study, along with some preliminary experimental results.

IEEE Vehicle Power and Propulsion Conference (VPPC) (17th. 2020. Gijón, Spain), This work has been partially funded from the EU H2020 R&I Program under grant agreement 864459 (Project ”TALENT”), and through ERFD Structural Funds. This wok has been partially supported by the Spanish Government, ID&R Office (MEC), under research grants ENE2016-77919 (Project “Conciliator”), and PID2019-111051RB-100 (Project “B2BEnergy”). This work has been partially supported by the government of Principality of Asturias (FICYT), under Grant FC-GRUPIN-IDI/2018/000241 and Severo Ochoa research grant PF-BP19-078.

Over the last decade, research on technologies to exploit tidal current kinetic energy for renewable electricity generation has had a significant growth. However, as to date, there is not a consensus worldwide on standard Power Take-Off (PTO) systems, due to the current immaturity of tidal energy converter technologies. In most cases, mechanical/electrical power conversion follows well-proven technologies derived by the mature wind-energy sector. However, the peculiarities of tidal energy resource impose ad hoc technology solutions. In this paper, different generator topologies and recent developments for marine tidal energy systems are reviewed and compared. The aim is to provide an overall perspective and identify areas for further development. Among considered technologies, the direct-drive permanent magnet synchronous generator by the full-rated frequency converter (FFC) represents an appealing solution, for reduced system complexity and maintenance requirements and possibility to develop smart Maximum Power Point Tracking (MPPT) strategies.

Rotor position transducerless control (self-sensing) techniques emerge as promising software-based sensor replacement strategy for redundancy concepts in industrial applications. Interior permanent magnet synchronous machine (IPMSM) drives offer the required physical properties for effective online motion state estimation. At low speed range including standstill, high frequency signal injection (HFSI)-based saliency-tracking methods estimate the rotor position solely utilizing terminal machine properties. However, implementation of HFSI is challenging and highly reliant on the given machine design. Load dependent non-linear phenomena can have detrimental effects on estimation accuracy and hence the required robustness, limiting the use in fail-operational safety-relevant applications. This paper proposes a modified implementation strategy for using HFSI as part of a position sensor redundancy concept for highly utilized IPMSM drives. A simple identification procedure is presented, isolating static position estimation errors. Experimental results confirm effective compensation of satuartion-induced errors, maximizing the fault-detection and fault-compensation capabilities of the proposed strategy even under heavy load conditions.

In the design processes of Switched Reluctance (SR) Machines that operate in wide constant power speed ranges, the maximum power available at maximum speed must be evaluated for every machine candidate. This is critical to ensure compliance with the power requirement. Important parameters to include in the design routine are the duration of the energizing period and the advance of the turn-on instant, i.e., advance angle. The latter is highly related to the machine geometry and is usually evaluated through time-consuming finite-element-based iterative methods. In this article, a simple, yet novel analytical model is proposed to cater for the torque-maximising advance angle in a closed-form analytical expression, directly from the machine geometry. The goal is to provide a non-iterative design tool that speeds up the design process. Successful validations against finite element analyses and experimental results on an SR machine prototype are reported. The main outcome of this article is shown by the improvement in computation time, without any significant loss of accuracy.

This work investigates the design of a multiphase coreless axial flux permanent magnet machine with concentrated windings, for the propulsion of an unmanned aerial vehicle. Such a system requires very high power and torque densities, which tend to be in contrast with other important requirements such as high efficiency and resilience. In order to simplify the design of the machine, an original method for the selection of the poles to coils ratio is proposed. The paper then presents a 3D finite element analysis based refinement for the final design; finally, a full scale prototype has been built and a preliminary no load test is reported.

This paper presents a closed-loop flux-weakening controller for hybrid-excitation synchronous machine drives based on separate regulation of amplitude and phase angle of the armature voltage. Operating point analysis is carried out to investigate the dynamic properties of the drive and to give guidelines in the tuning of the controller. Finally, experimental tests validating the theoretical derivations are performed on a prototype hybrid-excitation drive.

Extended Electro Motive Force Observers in the estimated synchronous reference frame allow to estimate rotor position at medium and high speeds for Interior Permanent Magnet Synchronous Machines. This paper focuses on the analysis of the dynamic performances of these observers. Use of complex vector modeling allows to demonstrate that these performances are speed dependent. In order to overcome this problem, a Complex Vector Observer is proposed. It is proven that this structure achieves good robustness against load torque and speed variations over different operating conditions. An improved phase detector is also presented, to solve the common speed reversal problems of the back-EMF based methods.

It is well reported that Switched Reluctance Machines typically operate in ‘single-pulse mode’ when rotating at high speed. For such operating mode, the control parameters are the duration of the energizing period along with the advance of the turn-on instant, i.e. advance angle. To maximize the output torque, the energizing period is normally kept equal to half of the electric period, i.e. 180°(elec.), whilst the optimal advance angle is evaluated through time consuming finite-element-based optimization algorithms. In this paper, a simple and novel analytical model is proposed that determines the optimal advance angle in a closed-form analytical expression, directly from the machine geometry. Successful validation against accurate finite element models on two Switched Reluctance prototypes is reported.

IEEE Vehicle Power and Propulsion Conference, VPPC 2019. Proceedings (2019. Hanoi, Vietnam), This work has been partially supported by: the EACEA, Education, Audiovisual and Culture Executive Agency from the European Commission, under Erasmus + Programme, Grant No. 574442-EPP-1-2016-1-ES-EPPKA1-JMD-MOB, EMJMD STEPS; the Government of the Principality of Asturias, Spain, under Grant No. FC-GRUPIN-IDI/2018/000241; and by FCT Portuguese Foundation for Science and Technology under Project UID/MULTI/00308/2019.

In this paper, it is shown how to obtain a low-cost, high-resolution, and fault-robust position sensing system for permanent-magnet synchronous motor drives operating in safety-critical systems, by combining binary Hall-effect sensors with high-frequency signal injection. It is shown that the position error signal obtained via signal injection can be merged easily into the quantization-harmonic-decoupling vector-tracking observer that is used to process the Hall-effect sensor signals. The resulting algorithm provides accurate, high-resolution estimates of speed and position throughout the entire speed range; compared to the state-of-the-art drives using Hall-effect sensors alone, the low-speed performance is greatly improved in healthy conditions and also following position sensor faults. It is envisaged that such a sensing system can be successfully used in applications requiring IEC 61508 SIL 3 or ISO 26262 ASIL D compliance, due to its extremely high mean time to failure and to the very fast recovery of the drive following Hall-effect sensor faults at low speeds. Extensive simulation and experimental results are provided on a 3.7-kW interior permanent-magnet drive.

This paper presents a sizing equation system for radial flux (RF) hybrid excitation synchronous machines (HESMs) with coaxial rotors. The system of sizing equations is derived integrating existing literature, mechanical, magnetic, thermal and control strategy considerations and coupled to a computationally-efficient finite element analysis (FEA) to assist the design of wide constant power speed range (CPSR) HESMs.

The aim of this paper is to further the knowledge on the inherent limitations imposed on variable speed drives by the resolution of the rotor position sensor. Starting from the well-known spatial harmonic formulation of quantized rotor position measurement, time harmonic formulations of both quantized position and speed are derived, which are valid under generic periodic torque disturbances. These formulations, based on modulation theory, justify the presence of otherwise unexplained additional rotor speed harmonics that are induced by the drive when subjected to torque disturbances. Simulations are provided to verify the correctness of the proposed mathematical representations.

This paper presents the design and experimental characterization of a radial flux (RF) hybrid excitation synchronous machine (HESM) topologically realized with two coaxial rotor sections, a salient pole wound field (WF) section and an interior permanent magnet section (PM). The machine design choices are analyzed with FEA simulations to predict the behavior at no-load and at nominal load. A no-load 10:1 voltage regulation and CPSR is experimentally characterized along with a partial load dynamometer mapping.

This work presents a rigorous approach to simplify the design optimization process for Switched Reluctance Machines. First of all, the dimension of the Design Space is found to be equal to twelve, as the number of Independent Design Variables. Then, constraints and requirements in the design are represented as inequalities to determine the limit surfaces, which are nothing else than the boundaries of the Design Space. By applying constraints and requirements one by one, the paper shows how it is possible to find the Actual Design Space, which includes only feasible solutions to the design problem. A case study clearly shows how, by means of this methodology, the size of the Design Space can be decreased by orders of magnitude.

In this work, an in-depth investigation was performed on the properties of the half-bridge current-source (HBCS) bidirectional direct current (DC)-to-DC converter, used to interface two DC-link voltage sources with a high-voltage-rating mismatch. The intended implementation is particularly suitable for the interfacing of a supercapacitor (SC) module and a battery stack in a hybrid storage system (HSS) for automotive applications. It is demonstrated that the use of a synchronous rectification (SR) modulation scheme benefits both the power-stage performance (in terms of efficiency and reliability) and the control-stage performance (in terms of simplicity and versatility). Furthermore, an average model of the converter, valid for every operating condition, is derived and utilized as a tool for the design of the control system. This model includes the effects of parasitic elements (mainly the leakage inductance of the transformer) and of the converter snubbers. A 3 kW prototype of the converter was used for experimental validation of the converter modeling, design, and performance. Finally, a discussion on the control strategy of the converter operation is included.

This paper investigates an original solution that can be used in the design of axial-flux permanent-magnet (AFPM) machines whenever a constrained shaft height requirement penalizes a standard design. A machine is tailored for electrical traction, but the ideas that are set forth are valid for any application with a constrained shaft height. Two design solutions that comply with a constrained shaft height are investigated, i.e., a standard Torus AFPM machine and an asymmetrically wound Torus machine, which is named “Ω AFPM” due to the shape of the stator winding. It is shown that the Ω AFPM machine has lower losses and higher efficiency. Finite-element simulations and experimental tests on a full-scale prototype confirm the validity of the proposed solution.

Axial flux permanent magnet (AFPM) machines are being increasingly used in a variety of industrial direct drive applications which benefit from their extreme axial compactness. In particular, slotted AFPM machines are of great interest since they allow to achieve high torque densities together with an acceptable constant power speed range. This paper analyzes a particular aspect related to the design of such machines, i.e., the use of soft-magnetic-composite wedges to close stator slots. This paper is the continuation of a previous investigation dedicated to the analysis of the no-load performance variation introduced by the magnetic wedges. Here, the attention is focused on the load performance by studying the effect of the wedges on d-q-axis stator flux linkages, torque production, and losses. The 2-D and 3-D finite element analyses are performed on a 10-kW AFPM machine, various magnetic wedge configurations are studied, and the load performance is compared with that of the same machine using nonmagnetic wedges, in terms of stator flux linkage, average and ripple torque, and magnetic losses. Finally, experimental tests and results on a full scale prototype machine mounting magnetic wedges are reported.

In this paper, the energetic management of the Segway PT i2 is studied. The Segway PT is a human transporter that uses two electric machines, one on each wheel. Each electric machines uses redundant set of windings to guarantee the safety. A multi-set of windings system offers several operating modes. Different kinds of control can then be obtained in normal and fault mode. First simulation results are given to test the simulation software for different faults. New energy managements are discussed to extend the range of the Segway. Energetic Macroscopic Representation helps to define the inversion-based control scheme of this complex architecture.

Hybrid Excitation Synchronous Machines allow broad flux regulation, and therefore a very wide Constant Power Speed Range. Literature shows that it is possible to build them both with a Single-Axis and with a Bi-Axial excitation. This paper presents a unified approach for the analysis, comparison and performance prediction of the two structures. Finite element simulation and experimental tests are carried out on a Torus-type Axial-Flux prototype, which — having two rotors, one equipped with PM and one with WE — allows for an easy structure reconfiguration on the same machine.

This paper reviews the progress that has been made in the analysis and design of axial-flux permanent-magnet machines over the past decade, with particular attention to aspects such as electromagnetic and thermal modeling, materials, manufacturing, pulsating torque, and extended speed range. Comparisons with other machine types and applications are also reviewed.

This paper presents a single-phase slotless axial-flux permanent-magnet synchronous machine for induction heating gensets. A full-scale prototype of the machine (110 kVA, 400 Hz, 690 A) has been designed and subsequently analyzed through finite element analysis (FEA). Induced current distributions in the permanent magnets and in the rotors have also been calculated through FEA, showing that the resulting losses are kept at bay due to the low armature reaction. An effective way of achieving regulation of the power transferred to the load has been analytically derived. The prototype has also been built, and experimental tests confirm the aforesaid analyses.

In this paper, binary Hall-effect sensor faults are investigated in rectangular-current-fed brushless dc (BLDC) drives and a very effective methodology for their detection, identification, and compensation is explored. It is shown that these faults cause erroneous commutation, generally leading to unstable operation. Using a fault detection and identification technique proposed by the authors in a recent paper on low-cost field-oriented drives, it is possible to pinpoint the faulty sensors. In this paper, it is demonstrated that the destabilizing effect of these faults on motion-state estimation can be compensated for in any position and speed estimation algorithm, as long as it is properly readapted. To this end, it is shown how to incorporate such fault-compensation in three state-of-the-art estimation algorithms: 1) the zeroth-order algorithm (ZOA); 2) the hybrid observer (HO); and 3) the vector-tracking observer (VTO). Comparative experimental tests are performed and it is verified that stable operation is achieved with three, two, or only a single Hall-effect sensor functioning correctly. These results show that the classical BLDC drive with three Hall-effect sensors has an inherent double redundancy to position-sensor faults. With the proposed method, this property can be exploited in systems that require very high reliability, such as in aerospace and automotive applications. Redundancy can be increased, using more than three Hall-effect sensors; reduced using two sensors; or eliminated using a single sensor, in ultra low-cost applications where redundancy is not a requirement.

The paper presents a closed loop flux weakening controller for Hybrid Excitation Synchronous Machines. The control is achieved though regulation of the voltage amplitude and of the phase angle between voltage and current. An operating point analysis is carried out, in order to determine the dynamic behavior of the drive. Finally, experimental tests are conducted on a prototype of axial flux hybrid excitation machine.

In this paper, two methods for flux linkage regulation in a starter/alternator with an axial-flux permanent magnet (AFPM) machine are proposed and compared. Desired regulation is achieved by two different mechanical solutions, each of them capable of modifying the amount of flux linkage through displacement of the two rotors in the AFPM machine. Constant power generation is thus achieved with very inexpensive devices that do not require external energy sources since energy in the airgap doesn't change. The main difference between the two proposed solutions is that the speed dependant device is ideally a constant voltage source while the torque-dependant device behaves as a constant current source. Even if some improvements are still needed, both devices introduce the totally innovative concept of mechanical flux weakening for AFPM power regulation in a wide speed range. Finally, the paper demonstrates that the introduction of these devices doesn't modify machine behavior in starting mode, so that the particular features of AFPM machines in terms of high torque density and overload capability remain unaffected

The objective of this paper is to investigate the properties of the Half Bride Current Source bidirectional DC to DC converter used to interface supercapacitors with batteries in a hybrid storage system. This work focuses on the benefits of applying synchronous rectification to the switches of the primary and the secondary side, both in terms of efficiency and control simplicity. In fact, by using this modulation scheme, it can be demonstrated that a single parameter (the duty ratio, D, of the dc link side top switch) can be used to control the converter under every operating condition. Furthermore, an average model of the converter valid in every operating condition is derived and utilized as a tool for the design of the control system. This model includes the effects of parasitic elements (mainly the leakage inductance of the transformer) and snubbers. Both the synchronous rectification switching scheme and the average model, have been experimentally validated with a 3 kW converter prototype. Also, the performance of a control strategy designed with such model are shown experimentally, This work has been partially funded by the Campus of International Excellence (CEI) of the University of Oviedo, Spain, in the framework of Mobility Grants for Academics in 2013, partially funded by the Gijon City Hall, by resolution of BOPA 156, 6-VII-2013. This work has also been partially supported by the Spanish Government, Innovation Development and Research Office (MEC), under research grant ENE2013-44245-R, Project “Microholo”, and by the European Union through ERFD Structural Funds (FEDER)

This paper investigates methods to achieve a wide constant power speed range (CPSR) in electric drives using hybrid excitation synchronous machines; five strategies are presented and compared. These range from state-of-the-art flux weakening based on demagnetizing armature current injection, to algorithms based on wound excitation (WE) current regulation, all the way to techniques involving both armature and WE current regulation. It is shown that one of these latter strategies allows a theoretically infinite CPSR and unity power factor operation throughout. This result is also verified experimentally, and a 10:1 range is demonstrated. Finally, a discussion is presented on practical limiting issues such as harmonic flux linkage components, inductance variations, and high-speed iron losses.