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In this study, the analytical design and electromagnetic performance comparison of a squirrel-cage induction motor (SCIM) and a wound-field flux switching motor (WFFSM) for high-speed brushless industrial motor drives is undertaken for the first time. The study uses analytical sizing techniques and finite element analysis (FEA) to model and predict the performance of both motors at a 7.5 kW output power. This study includes detailed equations and algorithms for sizing and modeling of both types of motors, as well as performance calculations that aid in motor selection, design optimization, and system integration. The main findings show that the SCIM has superior torque performance for starting and overload conditions, while the WFFSM offers advantages in power factor, efficiency over a wide operating range, and potential for higher peak power output. To this end, the WFFSM is capable of high-speed and high-efficiency operation while the SCIM is suitable for applications requiring variable speed operation. The validation study shows good agreement between analytical and FEA calculations for both motors. The results provide insights into the design and performance characteristics of both motors, enabling researchers to explore innovative approaches for improving their efficiency, reliability, and overall performance. [ABSTRACT FROM AUTHOR]

Featured Application: The research findings can be applied in the design of generators of various vehicles, in particular synchronous homopolar generators. Electric machines with hybrid excitation have increased torque density while maintaining a wide range of speed control. This article presents the results of the optimal design of a synchronous homopolar generator (SHG) with ferrite magnets on the rotor and excitation winding on the stator for passenger cars. The use of ferrite magnets on the rotor of a synchronous homopolar generator makes it possible to use the stator surface more efficiently, which in turn increases energy efficiency and reduces the dimensions of the generator. At the same time, the excitation winding on the stator provides a reliable brushless design and the ability to control the excitation flux. The problem of long-time calculation of the three-dimensional SHG structure, which is especially relevant when using multi-iterative computer optimization, is solved by using the computationally efficient Nelder-Mead method and a simplified SHG model using two-dimensional finite element analysis. It is also clear that the low torque ripple of SHG with ferrite magnets with two stator-rotor stack combinations (SRSC) is largely provided by the fact that the torque ripples of individual SRSCs are in antiphase. The problem of considering the magnetic properties of magnetic core sections made of structural low-carbon steel is discussed. It has been found that with an increase in both the saturation level of the magnetic circuit and the magnetomotive force (MMF) of the SHG excitation winding, resistance to irreversible demagnetization of ferrite magnets on the rotor can be increased by increasing their height. In addition, it is shown that there is a significant increase in performance when using the hybrid excitation, in comparison with the conventional SHG design without magnets. [ABSTRACT FROM AUTHOR]

In this paper, a brushless wound rotor vernier machine (Bl-WRVM) with a single inverter configuration is proposed to achieve the brushless operation. In the proposed topology, a single inverter is connected with series-connected ABC and XYZ windings through which the current flow produces the magnetomotive force with fundamental and sub-harmonic components, respectively. The XYZ windings have similar pole pairs to the excitation windings, whereas its number of poles is different from the ABC winding. A 24-slot stator, 4-pole armature ABC winding, 2 Pole armature XYZ and excitation windings, and 44-pole field winding for the outer rotor is designed and 2D finite element analysis is carried out to determine the performance of the machine. The proposed topology makes the Bl-WRVM cost-effective by applying only a single inverter as compared to a dual-inverter Bl-WRVM and it improves its torque quality.

Electrical energy is one of the energy that is needed in life. Greater attention should be paid to the use of non-renewable energy sources such as coal, natural gas and oil to generate electricity due to the limited supply of these energy sources and the environmental impact of residual waste from the production process. Therefore, another option that can be done is to use renewable energy. One example of renewable energy is solar energy whose utilization will have a more positive impact on the environment because this energy can be obtained from nature and never runs out. Environmentally friendly vehicles, both four-wheeled and two-wheeled vehicles based on hybrid and electric technology, have become one of the trends in which world transportation manufacturers are competing to develop transportation technology. The study conducted a design and numerical analysis for an electric motorcycle controller with a BLDC motor (brushless DC Motor). In this study using a BLDC motor because BLDC motors are superior to ordinary DC motors, these advantages include having higher efficiency, being durable, not using a brush, and almost not producing sound. In the experiment on June 1 at 14.00, the average solar panel voltage was 21.86 volts, the solar panel current was 1.71 Ampere, and produced 37.38 Watts of power, and from the BLDC motor rotation of 2215 Rpm. On average, BLDC motorcycles rotate bicycle tires every one hour interval from 08.00 to 17.00. In research, the best data from this study was obtained on the 6th day on June 6, 2022 with the 3 highest data, namely panel current of 1.861 volts, panel power of 35.84 amperes, and wheel rotation of 1841 Rpm. [ABSTRACT FROM AUTHOR]

Torque calculation is essential for selecting the appropriate motor to achieve the required torque at each joint of a hybrid exoskeleton. In recent years, the combined use of functional electrical stimulation (FES) and robotic devices, called hybrid robotic rehabilitation systems, has emerged as a promising approach for the rehabilitating of lower limb motor functions. Specifically, the implementation strategy of functional electrical stimulation walking aid combined with the design of the exoskeleton part is the main focus of our research team. This work copes with issues of the design process of a robotic exoskeleton. The importance of robotic exoskeletons for providing walking aid to people with mobility disorders or the elderly is discussed. Furthermore, the approaches to calculating the joint torques are investigated, and the mathematical models and parameters of interest are identified. This further includes the comparative data for servo motors: robotic exoskeleton characteristics and actuator analysis in the robotic exoskeleton. The aforementioned is used to propose a mathematical model based on previous models (Zatsiorsky BSP and Dempster BSP body segment parameters models, forward kinematics models), which was extended to include added adjustable parameters such as length, area, volume, mass, density, the centre of mass, human body characteristics, and considering both static and dynamic parameter extraction. Then, an analytic method is presented, exploiting the results from the mathematical model to select the appropriate motor for each joint of the lower extremities. The detailed description of the method is followed by examples, experimental measurements, and statistical analysis of qualitative and quantitative characteristics. The results showed deviations from typical calculation methods, offering a better understanding of the motor requirements for each joint of the exoskeleton and avoiding selections of marginal functionality features of the motors. In addition, researchers are offered a tool for replicating the results of this work, allowing them to configure the parameters associated with the servo motor features. The researcher can either use the embedded library developed for this work or enter new data into it, affecting the calculated torques of the model joints. The extracted results assist the researcher in choosing the appropriate motor among commercially available brushed and brushless motors based on the torques applied at each joint in robotic articulated systems. [ABSTRACT FROM AUTHOR]

This paper proposes a novel simplified brushless wound field synchronous machine (BL-WFSM) topology based on an uncontrolled three-phase rectifier. The output of the rectifier is injected into the common point of the star-connected three-phase armature winding. This arrangement develops an armature MMF consisting of two components: the fundamental MMF, which is rotating in nature, and the harmonic pulsating magnetic field, which induces the harmonic current in the specially designed harmonic winding of the rotor. The induced harmonic current is rectified through the full-bridge rectifier, which excites the main rotor field to achieve brushless operation and produce torque while interacting with the main fundamental rotating field of the armature. The proposed brushless topology is simple as it involves a single three-phase rectifier which does not require any complicated control strategy. Furthermore, this topology is a cost-effective solution as compared to the conventional brushless WFSM topologies since it does not require any additional hardware component except for a typical rectifier. In addition, the performance of the proposed brushless topology is better than the existing three-phase rectifier-based brushless scheme in terms of efficiency, output torque, and torque ripple. The proposed simplified BL-WFSM topology is validated through 2-D finite element analysis (FEA) using JMAG-Designer 19.1 to obtain the output torque of the machine.

Electrically excited synchronous machines (EESMs) with brushes and slip rings are popular in many application fields. Nevertheless, the brushes and slip rings of EESM would increase maintenance cost and reduce the reliability. Addressing this issue, this paper proposes a novel brushless electrically excited synchronous machine (BEESM) with arc-shaped rotor structure, whose armature and field windings are placed on the stator. Firstly, the special structure and operation principle of the BEESM are illustrated and studied. Then, the electromagnetic performance indexes, including the air-gap flux density, flux linkage, back electromotive force (back-EMF), cogging torque, output torque and losses are fully analyzed by finite element method (FEM). Finally, the proposed BEESM is optimized to suppress the cogging torque. The results indicate that the proposed BEESM could serve as a high reliability and cost-effective candidate for the electricity generation system and industrial drive.

Electric machines with hybrid excitation have increased torque density while maintaining a wide range of speed control. This article presents the results of the optimal design of a synchronous homopolar generator (SHG) with ferrite magnets on the rotor and excitation winding on the stator for passenger cars. The use of ferrite magnets on the rotor of a synchronous homopolar generator makes it possible to use the stator surface more efficiently, which in turn increases energy efficiency and reduces the dimensions of the generator. At the same time, the excitation winding on the stator provides a reliable brushless design and the ability to control the excitation flux. The problem of long-time calculation of the three-dimensional SHG structure, which is especially relevant when using multi-iterative computer optimization, is solved by using the computationally efficient Nelder-Mead method and a simplified SHG model using two-dimensional finite element analysis. It is also clear that the low torque ripple of SHG with ferrite magnets with two stator-rotor stack combinations (SRSC) is largely provided by the fact that the torque ripples of individual SRSCs are in antiphase. The problem of considering the magnetic properties of magnetic core sections made of structural low-carbon steel is discussed. It has been found that with an increase in both the saturation level of the magnetic circuit and the magnetomotive force (MMF) of the SHG excitation winding, resistance to irreversible demagnetization of ferrite magnets on the rotor can be increased by increasing their height. In addition, it is shown that there is a significant increase in performance when using the hybrid excitation, in comparison with the conventional SHG design without magnets.

Purpose: This study aims to compare surgical scrubbing with and without a brush in decreasing the number of germ colonies on hands. Background: Surgical scrubbing with and without a brush are currently popular worldwide. To date, the optimal method in decreasing the number of germ colonies on the hands is not known. Methods: Systematic review of effectiveness was conducted. The databases and publisher websites included PubMed, Science Direct, Google Scholar, Wiley Online Library, Cochrane Library and recruitment studies published between 2009-2019. The risk of bias was assessed utilizing Cochrane Collaboration's tool. Results: Included clinical studies consisting of five randomized controlled trials. The procedures and duration of surgical scrubbing on each study varied depending on the protocol as a reference. All clinical studies found no difference in the number of colonyforming units (CFU) on the hand between surgical scrubbing with and without a brush. Conclusions: Scrubbing with and without a brush showed similar efficacy in terms of the number of germ colonies on the hands. [ABSTRACT FROM AUTHOR]

This paper presents a novel dual-mode wound rotor synchronous machine (DWRSM) for variable speed applications. The proposed machine combines the advantages of both the conventional wound rotor synchronous machine (CWRSM) and the brushless wound rotor synchronous machine (BWRSM). Unlike the existing BWRSM, through the dual-mode operation of the proposed machine, constant torque is achieved in the constant torque region by operating the machine in mode-I, i.e., as a CWRSM, and constant power is achieved in the field weakening region by operating the machine in mode-II, i.e., as a BWRSM. The mode change is performed through an additional thyristor drive circuit. The airgap magnetomotive force (MMF) in both modes is derived analytically. To verify this principle, finite element analysis (FEA) and an experiment on a 1- horsepower prototype machine was performed, and key influential factors were verified. The transients in the stator currents and torque during the mode change was analyzed. The test results validated the correctness of the theory and the FEA results.

This paper proposes a cost-effective brushless technique for wound rotor synchronous machines (WRSMs). The proposed technique involves a traditional current-controlled voltage source inverter that utilizes a simple hysteresis-controller-based current control scheme and supplies three-phase currents to the armature winding of the machine. The supplied armature currents inherently contain fundamental-harmonic and third-harmonic current components. These unique armature current waveforms were previously realized by using dual-inverter-controlled schemes achieved with and without thyristor switches to develop brushless WRSM topologies. The fundamental-harmonic current component is applied to develop the main stator field, whereas the third-harmonic component is employed to realize the harmonic magnetomotive force, which induces a back electromotive force (EMF) in the harmonic winding located at the rotor periphery. The induced harmonic EMF is rectified to deliver a DC current to the rotor field winding through a full-bridge diode rectifier to achieve brushless operation. The proposed cost-effective brushless technique for WRSMs is validated using 2-D finite element analysis employing JMAG-Designer 19.1 to investigate the electromagnetic and electromechanical behaviors of the machine. Furthermore, the proposed technique is employed in machine topologies with different pole/slot combinations for the armature winding to achieve better performance.

This paper is about the use of BLDC motors in applications to the detriment of induction or brush motors. We have developed a software controller in Mathlab to control the BLDC motor in flow without hall sensors for low speeds and high power. By choosing small and precise speeds, both the stator flow and the rotor flow must be coordinated. [ABSTRACT FROM AUTHOR]

This manuscript proposes a wye-delta winding configuration for brushless operation of a wound field synchronous machine (BL-WFSM). In existing third harmonically excited BL-WFSM topologies, the additional third harmonic component of the stator magnetomotive force (MMF) was produced by an extra thyristor drive circuit or by utilizing an additional inverter. In the proposed single inverter topology, the stator winding is divided into two coil sets: the wye coil and delta coil. Triplen harmonic currents are produced owing to the delta coils set and start to circulate in the delta coils. This triplen harmonic circulating currents produce a triplen harmonic pulsating MMF in the airgap. The additional triplen harmonic pulsating MMF induces voltage in the rotor harmonic winding. This induced voltage in the harmonic winding is used to excite the rotor field. A 2D finite element analysis is performed, and the simulation results confirmed the operation principle of the proposed brushless topology. [ABSTRACT FROM AUTHOR]

Brushless doubly fed reluctance machines (BDFRM) are an attractive option for megawatt-scale turbo-electric propulsion systems due to use of a partially rated power converter, reduced maintenance, and absence of permanent magnets. Conventional design approach of a BDFRM uses equal electrical loadings on both stators and an initial phase offset $\delta$ of $\pi /2$ between the two stator currents. However, this approach leads to poor torque density because the machine saturates even before the stator reaches the current density limit. This article proposes an approach to maximize the torque density by finding appropriate electrical excitations on both stator windings for chosen machine dimensions as well as for specific flux density, current density, and grid voltage limits. A single-objective optimization problem is formulated. The optimized solution establishes that an initial phase offset $\delta$ of $2\pi /3$ produces 75% more torque as compared to the conventional $\delta = \pi /2$ design. The new design allows a higher stator currents injection without saturating the machine. The results are verified through extensive simulations using a finite element model. Operating with the optimized design also leads to higher machine efficiency and better power factor on the secondary stator, thus reducing the converter rating. [ABSTRACT FROM AUTHOR]

In this work, a cascaded doubly fed induction machine with a cage rotor is studied. To investigate the machine performance, a model is provided. In this model, the spatial harmonics of the rotor magnetomotive force are exactly considered. For this purpose, each rotor loop is selected as an individual circuit. The winding function theory is applied to compute the self- and mutual inductances of the rotor and stator circuits. To reduce the required simulation time, complex vector representation is adopted. Using the obtained voltage equations, the vector form of the machine state-space equations is yielded. Experimental tests are carried out to show the accuracy of the provided model. In addition, the adequacy of the proposed machine is verified by the appropriate tests. [ABSTRACT FROM AUTHOR]

In this paper, a new design configuration has been proposed in which a prototype of resonant inductive power transfer-based contactless power transfer to wound rotor has been developed which provides field power to brushless alternating current (BLAC) or brushless direct current (BLDC) motors without the use of permanent magnets in the rotor. Further, wound field in the rotor of DC motor can be powered without carbon brushes. The proposed design facilitates motor performance improvement by adding an extra dimension of field flux control, while the armature circuit is conventionally fed from position detection and commutation schemes. It contains a primary multilayer concentrated coil fed with high-frequency resonating AC supply or switched mode supply. A single layer helical secondary coil coaxially fixed on the shaft receives high frequency wireless AC power transmitted from primary coil. Fast rectifier inside the hollow shaft and DC filter provides the transferred DC power to field terminals in the rotor. It has been verified that rotor power can be varied linearly with linear variation in input DC power with the highest efficiency at the resonant frequency. Available power to the rotor remains invariable with rotational speed and angle, which is a necessary requirement for rotor field. DC voltage on the rotor terminals can be effectively controlled during standstill as well as during rotation at any speed. [ABSTRACT FROM AUTHOR]

A brushless doubly fed generator (BDFG) for wind power applications with a double-rotor structure is presented in this paper. First, field modulation ring and its application in the proposed BDFG are introduced. The geometric constraints of the field modulation ring are analyzed. Then, the operation principle of a variable-speed constant-frequency BDFG system is presented. The design of the BDFG is discussed, and finite-element analysis for the BDFG is carried out to obtain the performance of the machine. Finally, a small-size prototype machine is designed and manufactured to verify the theoretical analysis. The proposed BDFG has some advantages, such as high efficiency and high reliability. It has good potential on the applications of future large-scale wind power generation systems. [ABSTRACT FROM AUTHOR]

Many papers related to this topic can be found in the bibliography; however, just a modest percentage of the introduced techniques are developed to a Technology Readiness Level (TRL) sufficiently high to be implementable in industrial applications. This paper is focused precisely on the review of this specific topic. The investigation on the state of the art has been carried out as a systematic review, a very rigorous and reliable standardised scientific methodology, and tries to collect the articles which are closer to a possible implementation. This selection has been carefully done with the definition of a series of rules, drawn to represent the adequate level of readiness of fault detection techniques which the various articles propose.

To fabricate a semiactive type of damper that is comparatively compact and has low mechanical loss, the author developed an electromagnetic damper using a brushless direct drive DC motor. The damper comprises a ball screw mechanism and a brushless direct drive DC motor that acts as a generator. The motor consists of a rotor and a three-phase stator, and it is installed at the tip of the screw shaft. The lack of contact between the rotor and stator is an advantage. When a linear motion is converted into a rotational motion by the ball screw mechanism, the rotor is rotated, and electrical driving power is generated by electromagnetic induction. The damping effect of each phase is caused by kinetic energy dissipation by the electrical resistances connected to each terminal of coils. In this study, a test damper is fabricated, and theories of resisting force and rise time are introduced. Performance tests are carried out to confirm the theories and the dynamic properties of the damper for two winding configurations, and the experimental results are compared with the theoretical results. The damping effect is greatly generated and smoothly, but saturated in high frequency range, and switched quickly by SSR. It is possible to make the damper more efficient, compact, and sensitive. Finally, theories and the dynamic properties of the damper are confirmed.

This paper studies the cascaded doubly fed induction machine, operating as a brushless variable speed constant frequency generator supplying an isolated load. In isolated electric supply, the amplitude and frequency of the output voltage of the generator should be stabilized during the speed and/or load changing. Despite the complexity of the generator model, a simple indirect field-oriented vector control is elaborated to meet the output voltage requirements. Experimental results validate the proposed control approach. The study is extended to reveal the behavior of the controlled system under unbalanced load. [ABSTRACT FROM AUTHOR]

This paper investigates a flux-modulated double-rotor machine (FM-DRM) for series–parallel hybrid electric vehicles (HEVs). Based on flux-modulated gears, the FM-DRM has similar speed-torque characteristics. Two configuration schemes are analyzed and compared for the hybrid electric system based on the FM-DRM. The boundary operating conditions of the FM-DRM system are discussed. Moreover, the power flows regarding various operating modes are investigated and corresponding power equations are deduced. An HEV system based on the FM-DRM is simulated for a driving cycle of the United States Environmental Protection Agency to verify the various operating modes. A prototype FM-DRM is manufactured and tested by a driving cycle. The feasibility of using the FM-DRM as a power-splitting device for HEVs is validated by experimental results. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper presents a new brushless electrically excited claw-pole generator (EECPG) for vehicle power generation. The proposed design uses a toroidal excitation coil to magnetize all the stator poles and then generate effective power by complementary saliency effect of dual rotors. One salient advantage of this new design is its good excitation ability with minimized excitation copper loss as well as improved energy conversion efficiency. Meanwhile, the brush and slip rings are eliminated compared to the conventional rotor-EECPG. The generator structure is introduced, with its operating principle illustrated by 3-D finite-element predicated flux distribution. Rotor configurations using interlaced and non-interlaced types are both elaborated in terms of back electromotive force harmonic distribution and cogging effect. Load characteristic is predicted by the field-circuit coupled analysis, which proves the proposed brushless claw-pole generator could serve as a high-efficiency cost-effective candidate for vehicle power generation. [ABSTRACT FROM AUTHOR]

In recent years, Brushless DC (BLDC) motors have been gaining popularity as a solution for providing mechanical power, starting from low cost mobility solutions like the electric bikes, to high performance and high reliability aeronautical Electro-Mechanical Actuator (EMA). In this framework, the availability of fault detection tools suited to these types of machines appears necessary. There is already a vast literature on this topic, but only a small percentage of the proposed techniques have been developed to a sufficiently high Technology Readiness Level (TRL) to be implementable in industrial applications. The investigation on the state of the art carried out during the first phase of the present work, tried to collect the techniques which are closest to possible implementation. To fill a gap identified in the current techniques, a partial demagnetisation detection method is proposed in this paper. This technique takes advantage of the asymmetries generated in the current by the missing magnetic flux to detect the failure. Simulations and laboratory experiments have been carried out to validate the idea, showing the potential and the easy implementation of the method. The results have been examined in detail and satisfactory conclusions have been drawn.

Size and cost reduction are among the main issues of electric motor design and fabrication. This paper proposes an original layout for an axial flux permanent-magnet motor with printed circuit board (PCB) winding. In contrast to other axial flux motors of the same type, which are generally made with a three-phase fractional slot winding, the proposed motor has a two-phase wave winding printed on either side of the PCB. This configuration allows increasing the number of pole pairs and the supply frequency so to reduce the stator and rotor core widths. The winding is also characterized by a large copper percentage on the board, which improves the torque density of the motor. The results of the mathematical analysis, of the numerical simulation and of the experiments are compared. A method for the computation of the phase inductances is also proposed and validated. The main dimensions of the magnets are optimized via the finite-element method. The experimental comparison shows the advantages of the proposed motor in comparison to the traditional shaded pole motor for household applications. [ABSTRACT FROM PUBLISHER]

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A novel compound-structure transverse-flux permanent-magnet synchronous machine (CS-TFPMSM) is proposed in this paper, which is used in hybrid electric vehicles (HEVs) to fulfill the power-split function. The key component of the CS-TFPMSM is a brushless transverse-flux dual rotor machine (TFDRM). The TFDRM originates from the transverse-flux machines, and is capable of speed adjustment between the transverse-flux rotor and the permanent-magnet rotor without using any brushes. The structure and principle of the TFDRM are described. The torque equations of the TFDRM are deduced, which are different from those of traditional machines. Based on the investigation, the TFDRM tends to have high leakage and a poor power factor. The method to obtain high power factor is discussed. The back electromotive force (BEMF) and torque of the TFDRM are simulated with the variation of parameters, such as pole-pair number, width of the permanent magnets (PMs), and so on. A prototype of a 10kW TFDRM is designed.

A novel brushless double rotor machine (BDRM) is proposed in this paper. The BDRM is an important component in the brushless compound-structure permanent-magnet synchronous machine (CS-PMSM) system, which is a promising technology for power-split hybrid electric vehicle (HEV) applications. Compared with common double rotor machines, the brushes and slip rings required by rotating winding have been omitted in the BDRM, thus there are no such problems as maintenance, friction losses and so forth. Firstly, the torque characteristics of the BDRM are analyzed. As the stator has ring-shaped centralized windings, the size characteristics of the BDRM are different from those of conventional machines. The new sizing and torque equations are analyzed and the theoretical results are applied to determine the main dimensions. Additionally, studies of the analytical magnetic circuit and finite element method (FEM) model show that the BDRM tends to have high leakage flux and low power factor. Although the scope for improving the serious flux leakage of the BDRM is limited by the special magnetic topology, a method to obtain higher power factor is provided. Finally, a 10 kW prototype machine was manufactured, assembly of the prototype is discussed in detail and experimental tests are performed to validate the analytical and simulation results.

A new type of brushless double rotor machine (BDRM) is proposed in this paper. The BDRM is an important component in compound-structure permanent-magnet synchronous machine (CS-PMSM) systems, which are promising for power-split hybrid electric vehicle (HEV) applications. The BDRM can realize the speed adjustment between claw-pole rotor and permanent-magnet rotor without brushes and slip rings. The structural characteristics of the BDRM are described and its magnetic circuit model is built. Reactance parameters of the BDRM are deduced by an analytical method. It is found that the size characteristics of the BDRM are different from those of conventional machines. The new sizing and torque equations are analyzed and the theoretical results are used in the optimization process. Studies of the analytical magnetic circuit and finite element method (FEM) model show that the BDRM tends to have high leakage flux and low power factor, and then the method to obtain high power factor is discussed. Furthermore, a practical methodology of the BDRM design is developed, which includes an analytical tool, 2D field calculation and performance evaluation by 3D field calculation. Finally, different topologies of the BDRM are compared and an optimum prototype is designed.

The air-gap magnetic fields of brushless doubly fed induction machines (DFIMs) are complicated because of the cross-coupling between two stator fields via a special nested-loop rotor. Compared with classical analytical models, transient finite-element (FE) modeling is easier to evaluate the machine performance taking saturation into account. However, it is not efficient to evaluate lots of candidates in a large design space using transient FE models considering the time cost. In the transient simulation, the induced rotor currents are calculated by solving several time differential equations using the backward differentiation formula. This paper presents a computationally efficient FE analysis for brushless DFIMs. The induced rotor currents can be calculated using a single magnetostatic FE simulation. The average torque, losses, and efficiency can also be predicted using one magnetostatic solution. One candidate design can be evaluated within 1 or 2 min on a personal workstation. The efficient analysis is validated by the transient FE results. The presented model is applied to the optimization of a prototype. The influence of two construction variables, namely, pole-pair combinations and the number of loops per nest, is studied. One pole-pair combination is selected for manufacturing a prototype. [ABSTRACT FROM AUTHOR]

Recently, studies on the hybrid excitation synchronous motor using permanent magnet (PM) together with field windings have been actively conducted. In this regard, this paper seeks to investigate brushless hybrid excitation synchronous motors with improved rotors. The design was performed using an equivalent magnetic circuit to determine the best of four possible different structures. Using a finite-element analysis (FEA), the back electromotive force (EMF) per PM usage and the phase back EMF of each type were calculated and compared, and the design that can best reduce costs and increase torque density was determined. A detailed design of one of the four structures with excellent characteristics was performed, and the associated characteristics and problems were verified. An improved rotor structure was proposed to resolve the identified problems and improve performance. The phase back EMF and the total harmonic distortion of the phase back EMF, cogging torque, load torque, and torque ripple of the improved rotor structure were verified through the application of the FEA. In addition, the prototype motor was fabricated, and a no-load test was conducted to compare the test results and analysis results on the phase back EMF. The reliability of the analysis results was confirmed by comparison between test results and analysis results on the input current, line to line voltage, and efficiency under the same output conditions through the load test. [ABSTRACT FROM AUTHOR]

This paper presents an optimal design of the rotor pole in a novel axial-flux brushless doubly fed reluctance machine (AF-BDFRM), which features higher torque and power density than its counterpart radial-flux BDFRM. The rotor span and rotor overhang lengths were the optimized parameters, with the goals of improving torque density and improving the quality of the output power, i.e., reducing the torque ripple. The optimal design process was applied to obtain the optimized shape for maximizing torque density while minimizing torque ripple in a 16 kW machine. Then, the optimal design results were verified by means of the transient 3-D finite-element analysis. Furthermore, the results of the optimally designed rotor pole were compared with those of a previously developed diamond shape. Finally, a sample prototype of one HP was selected for testing, considering the manufacturing cost and available testing facilities to verify the proper working of the novel AF-BDFRM. [ABSTRACT FROM PUBLISHER]

This journal paper presents a vector control (VC) of an emerging brushless doubly-fed reluctance (BDFRG) technology for large wind turbine applications. The BDFRG has been receiving increasing attention due to its low operation and maintenance costs afforded by the use of partially-rated power electronics, and the high reliability of brushless assembly, while offering performance competitive to its traditional slip-ring counterpart, the doubly-fed induction generator (DFIG). A robust VC strategy has been developed for a custom-designed BDFRG fed from a conventional 'backto- back' IGBT converter. Preliminary studies have evaluated the algorithm under the optimum power factor control (OPFC) conditions which allow the improved efficiency of the generator-converter set and the entire wind energy conversion systems (WECS). [ABSTRACT FROM AUTHOR]

This paper presents an effective optimal design procedure for brushless permanent magnet (BLPM) machines based on an adaptive metaheuristic optimization technique. 2-D analytical expressions for the calculation of the magnetic flux density, electromagnetic torque, back electromotive force, and self-inductance and mutual-inductance are employed to optimally design a slotless brushless motor with surface-mounted magnets. The proposed approach combines the computational accuracy of the 2-D analysis and the computational speed due to the analytical expressions. The objective functions are the power losses and the motor volume to be simultaneously minimized subject to three constraints: 1) the required electromagnetic torque; 2) the required maximum rotational velocity; and 3) the limit of the stator core flux density. The optimization problem is solved using a fuzzy adaptive particle swarm optimization (FAPSO) technique. To evaluate the efficacy and effectiveness of the FAPSO technique, its results are compared with those of the conventional PSO and genetic algorithms. To investigate the influence of the armature current waveforms on the design results, three different optimization problems with different armature current waveforms (ideal rectangular, six-step, and sinusoidal), but identical objectives, constraints, and optimization variables are defined and solved. Finally, a BLPM machine has been designed and manufactured to experimentally show the effectiveness of the proposed technique. [ABSTRACT FROM AUTHOR]