Double Stator Switched Reluctance Machine Research Articles

Multi-mode operations of double-stator switched reluctance machine for electric vehicle

PurposeThe purpose of this paper is to introduce a double-stator switched reluctance machine (DS-SRM) for electric vehicles (EVs) and to propose multi-mode operations for this machine.Design/methodology/approachAnalysis of flux linkage distributions and torque characteristics using finite element method (FEM). Building a dynamic simulation model based on electromagnetic characteristics, mathematical equations and mechanical motion equations of the DS-SRM drive system. The paper proposes multi-mode operations (inner-stator excitation mode, outer-stator excitation mode and double-stator excitation mode) based on motor working regions. It also conducts simulation and experimental results to verify the effectiveness of the proposed multi-mode operations strategies and control schemes.FindingsThere is almost no electromagnetic coupling between the inner and outer stators due to the specially designed rotor structure and optimized windings polarity configuration. Analysis of flux linkage distributions and torque characteristics verified the independence of inner and outer stators. Proposal of multi-mode operations and corresponding control rules achieved the smooth switching between different modes.Originality/valueThe paper introduced the DS-SRM for EVs and proposed multi-mode operations, along with control rules, to optimize its performance. The specially designed rotor structure, optimized winding polarity configuration, and the proposed multi-mode operations contribute to the originality of the research.

Design of Novel Double-Stator Switched Reluctance Motor Drive System for Electric Vehicles

Design of Novel Double-Stator Switched Reluctance Motor Drive System for Electric Vehicles

Effects of Mechanical Offset Between Inner and Outer Stators in a Double Stator Switched Reluctance Machine

Effects of Mechanical Offset Between Inner and Outer Stators in a Double Stator Switched Reluctance Machine

Design and Multiobjective Optimization of a Double-Stator Axial Flux SRM With Full-Pitch Winding Configuration

In this article, a novel axial flux double-stator switched reluctance motor (AFDSSRM) is presented and optimized for electric vehicle applications. AFDSSRM adopts the axial arrangement of double-stator and inner rotor structure with a full-pitch winding configuration. The flux generated by the two stators cancels each other at the unaligned position, and then, a low unaligned inductance barely affected by saturation is achieved, which is the primary advantage of the AFDSSRM. First, the topology and power equation of the motor are presented briefly. Due to a large number of dimensional parameters of the proposed structure, comprehensive sensitivity analysis is used to classify the design parameters into strong- and weak-sensitive classes, and a multilayer optimization approach is adopted for the variables of both classes. The response surface method combined with the multiobjective genetic algorithm is employed to optimize the strong-sensitive variables, while the Taguchi algorithm is applied to optimize the weak-sensitive variables. Moreover, the 3-D finite element model is established to analyze the electromagnetic characteristics of the motor. Finally, a prototype motor is manufactured, and the experimental results verify the effectiveness of the proposed structure and the optimization method.

Integrated Drive Converter of SDS-SRM With Isolation and Nonisolation Charging Capabilities for Electric Vehicle

In this article, an integrated drive converter of segmented double-stator switched reluctance machine (SDS-SRM) with isolation and nonisolation charging capabilities for electric vehicle (EV) is presented. The proposed converter can not only reduce the number of the power switches, but also implement multiple operation modes. In nonisolation charging mode, the motor windings and existing power switches constitute a buck/boost converter to charge the battery. The appropriate rotor positions are obtained to achieve torque-free control, and the interleaved phase currents control method is introduced to reduce the charging current ripples. In isolation charging mode, the inner-stator is powered by the utility grid to drive the middle-rotor, and converts electrical energy into mechanical energy, while the outer-stator is operated in generation mode to convert mechanical energy into electrical energy. The SDS-SRM is served as a rotating transformer to transfer the electric power to charge the battery with the galvanic isolation function. A low power proof-of-concept prototype platform is built and experiments are carried out to verify the effectiveness of the proposed integrated drive converter and the corresponding control schemes.

A Magnetic Field Decoupling Double Stator Switched Reluctance Machine

This paper introduces a novel double stator switched reluctance machine (DSSRM). U-shaped stator blocks are used for both internal and external stators. Each stator tooth is wound with a central winding, and the polarities of the two stator teeth on each U stator block are opposite. Firstly, the working principle and the geometric design of the proposed DSSRM are given. The methods of reducing torque ripple from machine structure of the proposed DSSRM are illustrated. Then, this paper makes the comprehensive comparison between conventional DSSRM and proposed DSSRM by finite element method (FEM). The simulation results indicate that this proposed DSSRM has lower torque ripple and higher torque density than the conventional DSSRM. Finally, a prototype motor is manufactured and the simulation analysis is validated by the experimental results.

Design of a Low-Ripple Double-Modular-Stator Switched Reluctance Machine for Electric Vehicle Applications

To overcome the disadvantages of traditional switched reluctance machine (SRM) with moderate power/torque density and high torque ripple, this article proposes a novel double-stator SRM (DSSRM) with the inner and outer stators both adopting U-shaped segmental stator structure. By optimizing the polarity distribution of the inner and outer stator magnetic fields, the inner and outer stator magnetic fields are decoupled. Then, the relationships of torque ripple coefficient with the mechanical offset angles of the inner and outer rotor teeth are investigated. To optimize the mechanical offset angle and reduce the torque ripple of the motor, the initial design method is proposed, and five main parameters of the machine are optimized by the finite-element analysis. Then, the static magnetic characteristics and dynamic performance of this novel machine are simulated and analyzed. Finally, a 16/18/18/16 DSSRM is prototyped to validate the above simulation and theoretical analysis.

Principles and Implementation of a Novel Radial-Anti-Disturbance Bearingless Switched Reluctance Motor

In order to solve the problem that the vehicle flywheel battery is easy to be disturbed in the process of using, a novel radial-anti-disturbance bearingless switched reluctance motor (RADBSRM) is proposed and studied based on the double stator switched reluctance motor. By widening the width of rotor poles, the flat top regions of all main winding inductances for each phase are constructed. By adopting the two-phase-conducting decoupling control rules, the electromagnetic torque and the main levitation force can be provided simultaneously. The auxiliary windings and the permanent magnet comprised in the inner stator can provide auxiliary radial suspension force, which can increase the radial load capacity, and also reduce the power consumption for suspension. The basic topology, operation principle, control method, and electromagnetic characteristics were all analyzed. Compared with double stator bearingless switched reluctance motor (DSBSRM), the results of finite element analysis method (FEM) verified that the capacity and stability of radial suspension force are both improved.

Design Modification in Single-Tooth Winding Double-Stator Switched Reluctance Motor for Torque Ripple Mitigation

Double-stator switched reluctance motors (DSSRMs) with single-tooth winding topology possesses high torque density when compared to conventional switched reluctance motors (SRMs). However, their inherent high torque ripple is still an issue for industrial applications. In SRMs, the torque shared by the outgoing phase reduces significantly in the commutation region. However, at the same time, the incoming phase does not achieve sufficient torque generation. This results in a high torque ripple in this region. In this paper, several design procedures are discussed to improve the performance of the radial flux DSSRM with single-tooth winding topology. Firstly, the pole arc equations of stator pole and rotor segments for the higher difference between aligned and unaligned inductance are derived for high output torque and based on this, the selection of the number of stator slots/rotor segments is discussed. Furthermore, the influence of winding polarities on the core loss and output torque of DSSRM is discussed. Finally, the design modification in rotor structure is proposed with an angular shift in the alternate rotor segments in the direction of rotation to mitigate the torque ripple. To investigate the effectiveness of the proposed design modification, a finite-element model of a 3-phase 12/10/12 pole radial flux DSSRM is developed in ANSYS/MAXWELL software, and simulation results are presented. It is observed that a 40% reduction in the torque ripple is achieved in the case of the proposed motor. The proposed design modification improves the torque generating capability of the incoming phase in the commutation region, which reduces the torque dip in this region and subsequently reduces the torque ripple.

Research on Torque Ripple Minimization of Double-stator Switched Reluctance Motor Using Finite Element Method

Research on Torque Ripple Minimization of Double-stator Switched Reluctance Motor Using Finite Element Method

Development of a straight pole four‐phase double‐stator switched reluctance machine

This study introduces the development of the straight pole four-phase double-stator switched reluctance machine (SRM) which is considered to provide high torque density and low copper loss. The basic concept behind this design is to combine the features of the mutually coupled SRM and the double-stator SRM. In this study, the analytical method alongside the 2D finite element method (FEM) verification would be presented to reveal the developing path. Moreover, to verify the proposed SRM concept, the prototype machine has been designed and built. The performance result from 2D FEM is presented.

Comprehensive Report on Design and Development of a 100-kW DSSRM

Switched reluctance machines (SRMs) are low cost and fault tolerant alternatives for traction applications. Due to their relatively low torque density and high torque ripple, these machines have not been used in commercialized electrified power trains yet. The double-stator magnetic configuration, where a segmental rotor shared between two stators, is proven to have superior torque density, lower acoustic noise, and torque pulsation. The double-stator SRM (DSSRM) has a high potential of being the next generation of traction motors since it combines the advantages of permanent magnet-free machines, such as low cost and independence from supply chain issues associated with rare metals, while providing high torque and power densities. This paper introduces the complete design process of a 100-kW DSSRM including electromagnetic, structural, thermal, and system level design. The performance of the developed DSSRM is verified with the experimental data. This paper presents overall study of DSSRM and describes merits of DSSRM drive system.

Comparison of winding configurations in double‐stator switched reluctance machines

The double-stator configuration of the switched reluctance machine (SRM) aims to maximise the energy conversion efficiency by optimising the ratio of motional force to the total magnetic force. Maintaining the attractive features of SRM, the double-stator switched reluctance machine (DSSRM) proves to have higher torque/power density than the conventional SRM, which is a crucial feature for traction applications. The original winding configuration used in DSSRM is the full-pitch winding, which yields high-power density but causes significant heat within the machine's end windings. As end windings do not take part in torque generation, concentrated windings were proposed to reduce the heat as well as to reduce the size, cost, and weight of the machine. This study provides a detailed comparative analysis of the effects that the winding configuration has on the performance of a 100 kW DSSRM, with emphasis on flux density distribution, efficiency, and heat generation. It is concluded that the concentrated windings are a better alternative to the full-pitch windings in DSSRM.

Thermal analysis of Double Stator Switched Reluctance Machine (DSSRM) with and without a squirrel cage rotor

Abstract Double Stator Switched Reluctance Machine (DSSRM) is a novel switched reluctance machine with limited information about its heat distribution and dissipation. This paper presents a two dimensional (2-D) thermal analysis of Double Stator Switched Reluctance Machine (DSSRM) to observe actual heat distribution in the parts of the machine, using Finite Element Method (FEM). Two topologies for the rotor of DSSRM are considered, Non-Squirrel Cage Double Stator Switched Reluctance Machine (NSC-DSSRM) and Squirrel Cage Double Stator Switched Reluctance Machine (SC-DSSRM). The heat distribution of these two topologies is analyzed, using Computational Fluid Dynamics (CFD). Finally the results are presented and compared.

Opportunities and Challenges of Switched Reluctance Motor Drives for Electric Propulsion: A Comparative Study

Selection of the proper electric traction drive is an important step in design and performance optimization of electrified powertrains. Due to the use of high energy magnets, permanent magnet synchronous machines (PMSM) have been the primary choice in the electric traction motor market. However, manufacturers are very interested to find a permanent magnet-free alternative as a fallback option due to unstable cost of rare-earth metals and fault tolerance issues related to the constant permanent magnet excitation. In this paper, a new comprehensive review of electric machines (EMs) that includes various new switched reluctance machine topologies in addition to conventional EMs such as PMSM, induction machine, synchronous reluctance machine (SynRel), and PM-assisted SynRel is presented. This paper is based on performances such as power density, efficiency, torque ripple, vibration and noise, and fault tolerance. These systematic examinations prove that recently proposed magnetic configurations such as double-stator switched reluctance machine can be a reasonable substitute for permanent magnet machines in electric traction applications.

Radial Force Reduction in a New Flat-Type Double-Stator Switched Reluctance Motor

The inherent structure of double-stator switched reluctance motor (DSSRM) provides a significant improvement in energy conversion efficiency by eliminating the radial component of the forces. Reduction of the radial force (RF) in rotational motion increases efficiency and performance of the machine. This paper proposes and implements a new flat-type double-stator segmented cup-rotor SRM (DSSCR-SRM). In this structure, the shaft is placed on one bearing, which reduces the system cost and friction. The rotor structure is designed to be connected directly to the load (direct-drive system) without the shaft requirement. Moreover, the rotor can be balanced between two stators such that the resultant RFs is reduced to zero. Due to the difference between the number of turns in inner and outer stator-coils, the forces exerted on the segmented rotor will cause it to stay partially suspended. In order to improve the results and determine appropriate performance of the motor, the magnetic analysis has been done on a 3-D model. The results of analytical calculations and the finite-element method analyses are validated by testing a prototype model of the DSSCR-SRM.

A New Strategy for Design and Analysis of a Double-Stator Switched Reluctance Motor: Electromagnetics, FEM, and Experiment

The double-stator switched reluctance motor (DSSRM) has a potential to produce more power per volume than other types of SRMs. This paper offers a new design strategy concentrating on power rating to calculate the dimensions of a DSSRM. The new strategy is based on dissecting the DSSRM into two inner and outer rotor SRMs. In this regard, both inner and outer rotor SRMs are designed separately, and then, the results are merged together. The characteristics of the DSSRM are achieved utilizing analytical design and 3-D finite-element analysis (FEA). In addition, the obtained results are compared with dual SRM. To determine the appropriate performance of the motor, the magnetic analysis is performed utilizing a 3-D model. In addition, to achieve optimal operation, two different winding configurations are investigated and compared with each other. Finally, a prototype of the flat-type cup-shape DSSRM with a segmented rotor is fabricated and tested in the laboratory. The results of the analytical calculations and the FEA are validated by a testing motor, which show the accuracy and the design strategy, and it can be extensible to other types of motors.

Thermal Modeling and Analysis of a Double-Stator Switched Reluctance Motor

In this paper, thermal modeling and analysis of a 10 kW double-stator switched reluctance machine (DSSRM) is presented. Thermal management is an essential step of the machine design, since overheated windings and cores might destroy the insulation and lead to failure of the machine. A three-dimensional (3-D) finite-element method (FEM) has been used to numerically calculate the temperature distribution in different parts of the machine. Furthermore, to include the use of water as coolant, computational fluid dynamics (CFD) has been utilized. Thermal performance of the prototype is then analyzed at various load conditions. A 10 kW prototype of the DSSRM has been built and the results have been experimentally verified.

Modeling and Simulation of a 16/12 Double Stator Switched Reluctance Motor

Abstract. Modeling of a switched reluctance motor (SRM) is to predict the motor performance with a reasonable estimate over a wide range of speed and torque. Obtaining the realistic model of SRM which operates in a region of magnetic saturation due to complex structural implementation progress is too complicated process, with long response time. This paper introduces a linear model of double-stator SRM (DSSRM) which will be applied on direct-drive washing machine application. The proposed method uses a developed simple magnetic equivalent circuit for modeling a DSSRM. The electromagnetic characteristics of the designed DSSRM are analyzed by finite element method (FEM) to validate the extracted results of the model. Finally, the experimental results with appropriate accuracy are achieved for modeling and magnetic analysis of the evaluated DSSRM.

A Double-Stator Switched Reluctance Motor for Direct-Drive Washing Machine Application

Abstract. Switched reluctance motors (SRMs) are known as an economical solution by several unique features such as: simple structure and low cost maintenance. Furthermore, due to the lack of permanent magnet, powerful and economical structure of these types of motors, they are proposed as a good choice for use in household appliances. In this paper, a high power flat-type double-stator SRM with low operating voltage in direct-drive system is introduced. Initially, proportional to the intended application, the acceptable attribute of SRM structure is selected, and was followed by the calculation of the motor design. Next, the magnetic characteristics are analyzed by finite element method (FEM) to determine the efficiency of the motor. Finally, the collection of experimental data is tested to confirm the calculated values and the simulation results and ensure the proper functioning of the obtained collection.