Segmented Rotor Research Articles

Torsional Vibration Analysis and Suppression of Interior Permanent Magnet Synchronous Motor With Staggered Segmented Rotor for Electric Vehicles

Torsional Vibration Analysis and Suppression of Interior Permanent Magnet Synchronous Motor With Staggered Segmented Rotor for Electric Vehicles

Performance Analysis of a Novel Axial Radial Flux Segmental Rotor Switched Reluctance Motor

Based on the characteristics of axial flux switched reluctance motor (SRM) and radial flux SRM, this paper proposes a new type of axial radial flux segmental rotor switched reluctance motor (ARFSRSRM). The motor has the left and right dual axial stator structures, which forms a kind of axial flux path with the segmental rotor in the middle, and a radial stator structure, which shares a kind of radial flux path with the segmental rotor on the outside of the motor. Compared with the conventional SRM, this motor combines the advantages of high output torque and torque density due to the inclusion of two kinds of flux paths, making it suitable for high-efficiency and high-torque fields such as electric vehicles. In this paper, the topology and operating principle of the new motor are first introduced. Then the initial structural parameters are derived, and the multi-objective optimization of the proposed motor is carried out using Taguchi’s algorithm. The static and dynamic performance of the motor is comprehensively analyzed using the 3-D finite element method. Finally, the experimental results obtained through the trial production of a prototype machine verify the good performance of the new motor.

Influence of temperature on power factor and operating area of SynRM machine in automotive equipment

Across various applications, electrical machines are intensely replacing conventional hydraulic and pneumatic actuators in applications with a higher degree of complexity. In our previous study, a SynRM machine with a segmented rotor was designed to operate as a clutch actuator, to be placed in the gear housing which suffers from a high ambient temperature. This makes it necessary to predict the considerable potential influence of temperatures. This study evaluates the influence of winding resistance variation due to temperature on the machine power factor and its operating area. The evaluation is done for the condition of the automotive battery supply of 14 V, 50 A. An experimentally validated analytical model based on the SynRM machine phasor diagram was used to assess the torque-speed area and power factor variation. The main contribution is presented in the form of a tool represented as an abacus that allows the user of the machine to track the power factor and maximum speed for a range of winding resistance values. On a selected operating point of (Γ, N) = (0.57 N.m, 3500 rpm), it is demonstrated that the winding resistance should be reduced below 0.2 Ω, to be able to achieve the targeted speed, while the power factor is at 0.9.

Analytical Inductance Modeling of Segmental Rotor Switched Reluctance Motor with Single-Tooth Windings

Analytical Inductance Modeling of Segmental Rotor Switched Reluctance Motor with Single-Tooth Windings

Impact of Silicon Steel Laminating Materials in Modified Segmented Rotor Switched Reluctance Motor: Electromagnetic and Vibrational Analysis

Impact of Silicon Steel Laminating Materials in Modified Segmented Rotor Switched Reluctance Motor: Electromagnetic and Vibrational Analysis

Design, Modelling and Optimization of a High Power Density Axial Flux SRM with Reduced Torque Ripple for Electric Vehicles

Switched reluctance machines (SRMs) are potential candidates for use in the propulsion systems of electric vehicles. However, they suffer from low power density and high torque ripple. In this paper, a segmented rotor double-sided axial flux SRM (DSAFSRM) is chosen for detailed analysis. A hybrid design algorithm is proposed to take the effects of iron non-linearity into account. The proposed design procedure benefits from simplicity and high accuracy at the same time. A two-step optimization procedure is presented which minimizes the torque ripple of the DSAFSRM without jeopardizing its efficiency. The torque ripple is reduced from 120% to 35% after optimization. In the two-step optimization procedure, both geometrical and switching related parameters are investigated. Moreover, a double-sided radial flux SRM is designed and compared with the proposed DSAFSRM in terms of torque ripple, average torque, efficiency and power density. The results indicate superior performance of the optimized DSAFSRM, especially in terms of average torque, which is 26% higher than the torque produced by the double-sided radial flux SRM.

Comparison and Experimental Verification of Different Approaches to Suppress Torque Ripple and Vibrations of Interior Permanent Magnet Synchronous Motor for EV

Interior permanentmagnet (IPM) motors have been the most promising solutions for electric vehicles (EV) drives in terms of torque/power density, compactness, and efficiency. However, IPM motors are vulnerable to large torque ripple and high-level electromagnetic vibrations due to the differences of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d-&amp;q</i> -axis inductance and abundant spectrum of exciting forces. This article presents an intensive comparison of IPM motors with three design approaches to reduce cogging torque, torque ripple, and electromagnetic vibration. The design approaches compared cover skewing slot and segmented rotor approaches commonly used in industry, as well as a new asymmetric pole approach. A commercial 10 kW 8-pole/ 48-slots V-shaped IPM motor for EV traction is taken as the reference base. Extensive performance comparisons, including cogging torque, back-EMF, load current, load torque profiles, PM reliability, and torsional force were carried out. Besides, vibration aspects in terms of exciting force, modal property, and electromagnetic vibration response were also analyzed and compared. Finally, the prototypes with the mentioned three design approaches are produced, respectively, and intensive experimental tests were done to verify the analysis and comparison.

A Comprehensive Performance Comparison between Segmental and Conventional Switched Reluctance Machines with Boost and Standard Converters

This paper presents the comparisons between two types of switched reluctance machines (SRMs) and SRM converters. An SRM with a segmental rotor is compared with a conventional SRM (CSRM), and an SRM converter containing a passive boost circuit is compared with a conventional asymmetric half-bridge (AHB) converter. The segmental SRM has an asymmetric rotor with a segmented structure. The four rotor segments are made of steel laminations. Two segments are misaligned with the other two by 15 degrees. The torque ripple of the SRM with this structure is decreased, and the static torque is increased compared to a conventional SRM. The boost converter comprises a front-end circuit and a conventional AHB converter. The front-end circuit boosts the voltage level. The boosted voltage accelerates the rising and falling progress of the phase current. In this way, the SRM can obtain a greater speed and a smaller torque ripple. The comparison is conducted in simulation and validated through the experimental results. The experiment results have demonstrated that the segmental SRM obtains a maximum 7% torque ripple reduction at a low-speed range, compared to the CSRM. With the boost converter, both the CSRM and the segmental SRM can achieve a lower torque ripple and a higher maximum speed.

Characteristics Evaluation of a Segmental Rotor Type Switched Reluctance Motor with Concentrated Winding for Torque Density and Efficiency Improvement

With the rapid development of power electronic techniques and the increasing cost of permanent magnets (PMs) materials, switched reluctance motors (SRMs) have recently gained more attention. However, traditional SRMs have a relatively low torque density. For the sake of increasing the motor torque density, this paper proposes a novel segmental rotor type SRM. The proposed motor adopts hybrid stator poles and concentrated windings in the stator side and a segmental rotor structure in the rotor side, which is completely different from the structures of the traditional SRM. The special structure of the motor shortens the magnetic flux paths of the motor, separates the parts of the magnetic flux paths from one another, and eradicates the magnetic flux reversal in the motor stator in order to improve the electric utilization and output torque density of the motor. Meanwhile, the requirement of the magneto-motive force and the core loss of the motor is also decreased, thereby improving the efficiency of the motor. For the purpose of proving the proposed structure, the characteristics of the motor are analyzed using the finite element method and are compared to those of the traditional 12/8 SRM, which is designed for the same application. Moreover, the prototypes of the traditional 12/8 and proposed SRMs are manufactured, and experiments based on the prototypes are performed. Finally, the effectiveness of the structure of the proposed motor is further proven by the experimental results.

Design, analysis and comparison of switched reluctance motors for electric vehicle application

This paper presents the design, analysis and comparative study of three different configurations of Switched Reluctance Motor (SRM) suitable for In-wheel application in Electric Vehicles. C-core stator with dual rotor SRM, C-core stator with disk-type segmented rotor SRM and Dual gap inner segmented rotor SRM are designed and compared for the same stator/rotor pole, supply current, current density and outer diameter. The significant performance indices of an electric motor for an in-wheel application, such as torque ripple, torque per unit active weight and torque per unit active volume, are considered for analysis. 3D Finite Element Analysis (FEA) of the machines is performed using the software MagNet 7.5 due to the axial field distribution of the configurations. The best among the three configurations is fabricated and experimental results are presented.

Evaluation of direct-quadrature position and saturation of a SynRM machine with Segmented Rotor

The synchronous reluctance machine has gained popularity in traction and other smaller application thanks to its design that need very little or even no permanent magnet. Without internal permanent magnet assistance, an adequate level of torque density could be achieved by having an optimized rotor design to attain the optimum ratio of direct inductance over quadrature inductance. In order to properly control the machine, the direct and quadrature position need to be identified. In this study, a segmented rotor topology without permanent magnet was chosen. We evaluate the direct and quadrature position of the rotor topology, its saturation level and provide the flux linkage and the inductances of the machine.

Torque Ripple and Electromagnetic Vibration Suppression in Permanent Magnet Synchronous Motor Using Segmented Rotor With Different Pole Widths

In current engineering, the skewing slots approach is commonly used for permanent magnet synchronous motor (PMSM) to reduce torque ripple and electromagnetic vibration. However, this approach may limit the axial length of the motor and increase the manufacturing cost. This article studies a segmented rotor with different pole widths approach to mitigate torque ripple and electromagnetic vibration for PMSM, which has a lower implementation cost and facilitates mechanized production. The mapping relationship between geometric dimensions and torque performance is obtained, and the optimal dimensions are determined. An 8-pole/48-slot V-shaped PMSM is taken as the original motor, and the influence of engineering error on the torque performance of the presented approach is discussed. The electromagnetic performances and vibration responses of the motor with the presented approach are compared with that of the skewing slot motor to verify the effectiveness of the presented approach. Finally, prototypes are built, and intensive experimental tests are carried out to verify the analysis and comparison.

Design Optimization of a Switched Reluctance Machine with an Improved Segmental Rotor for Electric Vehicle Applications

In this article, a switched reluctance machine (SRM) with six phases and a misaligned segmental rotor is proposed. The segmental rotor has an internal 15-degree misalignment, allowing the SRM structure to be a one-layer 2D structure with a short flux path structure. The proposed SRM produces a relatively low torque ripple by exciting two phases simultaneously. Additionally, an optimization method is applied, allowing for the maximum torque position of one phase to be aligned with the zero-torque position of the adjacent phase. The finite element method (FEM) is used to analyze and design the proposed SRM and to simulate the proposed liquid cooling system. The static torque waveforms are analyzed, and the dynamic torque waveforms are simulated with a drive using SiC MOSFETs. Finally, a prototype is manufactured, and the experiment is performed to validate the design and simulation results.

Torque Characteristic of Switched Reluctance Motor with Hybrid Excitation Segmented Rotor

Torque Characteristic of Switched Reluctance Motor with Hybrid Excitation Segmented Rotor

Potential of damage accumulation during segmented rotor blade fatigue tests

Modern wind turbines have higher rated power and improved capacity factors. This results in very long and slender blades which are also designed closer to the material limits. As a consequence, blade test facilities need to be upgraded for static and fatigue full-scale blade testing to carry larger loads and deal with larger tip deflections. Another aspect is the adaption of the test methods to avoid high overloads, which can cause premature damage and require time-consuming repairs. One drawback of traditional full-scale tests with a full-length rotor blade is the long time needed for certification as the blades have low eigenfrequencies and hence high fatigue test durations. This work presents an alternative fatigue testing approach for rotor blades which combines full-length and segmented fatigue tests, each contributing to the accumulated fatigue damage. The proposed approach is benchmarked with the traditional approach by means of a numerical optimization study. applying this approach to a current offshore rotor blade design illustrates the potential for reducing the fatigue test duration by 66% and the local fatigue damage overload to a mere fraction.

Effect of Rotor Topology on the Performance of Counter-Rotating Double-Sided Flux Switching Permanent Magnet Generator

Recently, electric power generation from direct-drive counter-rotating wind turbine has gained considerable attention. Consequently, employing an efficient and a high power density electric generator is important. In this regard, flux switching permanent magnet generator with double-sided structure is one of the potential candidates for this purpose due to its features like inherently magnetic gearing effect, high power density, high reliability, and robust rotor structure. In this regard, rotor structure of double-sided flux switching permanent magnet generator is one of the most important factors which can highly affect the machine's performance due to the fact that, rotor geometry is the main part in the flux switching procedure of double-sided flux switching permanent magnet generator. Consequently, this paper presents a comprehensive analysis of counter-rotating double-sided flux switching permanent magnet generator with segmented rotor and laminated rotor in which a bridge is located between adjacent rotor poles. The finite element simulations and experimental tests results showed that the proposed generator with laminated rotor gained from the higher power density in comparison with the segmented one whereas in the case of segmented rotor, the torque ripple is lower.

Analysis of Influence of Stator and Rotor Pole Shape on Electromagnetic Performance of Flux Switching Motor With Segmental Rotor

According to the relationship between the stator and rotor structure and magnetic flux density of the traditional flux switching motor with segmental rotor (SFSM), the mathematical model of the SFSM was established. It was found that the height of the stator pole shoe has a great influence on the no-load electromagnetic characteristics of the motor. After the flux barrier was added on the segmental rotor, it can effectively solve the problem that the positive and negative half period of the no-load electromotive force (EMF) waveform of the motor with low pole shoe height. Using the method of finite element (FEM) parametric simulation, the optimal size of the flux barrier was obtained. Compared with the traditional SFSM, the even harmonics in the phase winding EMF waveform were greatly reduced, and the inductance waveform tends to be sinusoidal. Finally, a prototype was made, and the correctness of the new segmental rotor structure was verified by experiments.

On Analytical Modeling of the Air Gap Field Modulation in the Brushless Doubly Fed Reluctance Machine

The brushless doubly fed reluctance machine (BDFRM) is receiving an increased amount of attention from the research community thanks to its potential as an alternative drive for variable speed applications, both as motor and generator. Currently, the sizing of the BDFRM in the literature is based on the model of an ideal axially laminated rotor (ALR) and discrepancies are hidden in compensation factors which are in turn tuned with a finite element analysis (FEA). This paper proposes an analytical framework to accurately model the air gap field modulation, and by extension the torque density, of the BDFRM with ducted segmental rotor (DSR) and salient pole rotor (SPR). The results are verified with FEA and validated on a BDFRM prototype.

Segmented Rotor Mutually Coupled Switched Reluctance Machine for Low Torque Ripple Applications

Mutually coupled switched reluctance motors (MCSRMs) are alternatives in the family of reluctance machines that can overcome switched reluctance motor's (SRM's) system-level integration and control challenges by utilizing standard three-phase voltage source inverters. In this article, a novel segmented-rotor, fractional-slot, tooth-wound MCSRM with notched rotor design is presented, which has very low torque ripple compared to other machine types in the SRM family. The torque ripple is reduced to 3.6% without utilizing any current profiling techniques or torque sharing functions. The ripple minimization is achieved primarily through rotor segment shaping, which has a strong influence on stator flux densities, flux linkages, and torque harmonics. The design strategy, along with the optimization details, is presented for a 120 W, 12 slot-8 pole MCSRM. The designed MCSRM is prototyped for experimental verification and validation of the finite element analysis results and design methodology.

Switched Reluctance Motors and Drive Systems for Electric Vehicle Powertrains: State of the Art Analysis and Future Trends

This paper presents a detailed literature review on switched reluctance motor (SRM) and drive systems in electric vehicle (EV) powertrains. SRMs have received increasing attention for EV applications owing to their reliable structure, fault tolerance ability and magnet free design. The main drawbacks of the SRM are torque ripple, low power density, low power factor and small extended speed range. Recent research shows that multi-stack conventional switched reluctance motors (MSCSRM) and multi-stack switched reluctance motors with a segmental rotor (MSSRM-SR) are promising alternative solutions to reduce torque ripples, increase torque density and increase power factor. Different winding configurations such as single-layer concentrated winding (SLC), single layer mutually coupled winding (SLMC), double layer concentrated winding (DLC), double layer mutually coupled winding (DLMC) and fully-pitched winding (FP) are introduced in the literature in recent years to increase average torque and to decrease torque ripples. This research analyzes winding methods and structure of the SRMs, including conventional and segmental rotors. They have been compared and assessed in detail evaluation of torque ripple reduction, torque/power density increase, noise/vibration characteristics and mechanical structure. In addition, various drive systems are fully addressed for the SRMs, including conventional drives, soft-switching drives, drives with standard inverters and drives with an integrated battery charger. In this paper, the SRM control methods are also reviewed and classified. These control methods include strategies of torque ripple reduction, fault-diagnosis, fault-tolerance techniques and sensorless control. The key contributions of this paper provide a useful basis for detailed analysis of modeling and electromechanical design, drive systems, and control techniques of the SRMs for EV applications.