Hybrid-excited Flux-switching Machine Research Articles

Design and Many-Objective Optimization of an In-Wheel Hybrid-Excitation Flux-Switching Machine Based on the Kriging Model

Design and Many-Objective Optimization of an In-Wheel Hybrid-Excitation Flux-Switching Machine Based on the Kriging Model

Design and Hierarchical Coordinated Optimization of an Outer-Rotor Hybrid-Excitation Flux-Switching Machine for In-Wheel Driving Applications

Design and Hierarchical Coordinated Optimization of an Outer-Rotor Hybrid-Excitation Flux-Switching Machine for In-Wheel Driving Applications

Subdomain modeling of linear hybrid excited flux switching machine

PurposeThis paper aims to develop an analytical approach to validate the finite element analysis (FEA) results. FEA itself is a powerful tool to evaluate the performance of electrical machines but takes more time and requires more drive storage. To overcome this issue, subdomain modeling (SDM) is used for the proposed machine.Design/methodology/approachSDM is developed to validate the electromagnetic performance of a new linear hybrid excited flux switching machine (LHEFSM) with ferrite magnets. In SDM, the problem is divided into different physical regions called subdomains. Maxwell's governing equation is solved analytically for each region, where the magnetic flux density (MFD) is generated. From the generated MFD, x and y components are calculated, which are then used to find the useful force along the x-axis.FindingsFEA validates the developed SDM via JMAG v. 20.1. The results obtained show excellent agreement with an accuracy of 95.13%.Practical implicationsThe proposed LHEFSM is developed for long stroke applications like electric trains.Originality/valueThe proposed LHEFSM uses low-cost ferrite magnets with DC excitation, which offers better flux regulation capability with improved electromagnetic performance. Moreover, the developed SDM reduces drive storage and computational time by modeling different parts of the machine.

Analysis of Linear Hybrid Excited Flux Switching Machines with Low-Cost Ferrite Magnets

Linear hybrid excited flux switching machines (LHEFSM) combine the features of permanent magnet flux switching machines (PMFSM) and field excited flux switching machines (FEFSM). Because of the widespread usage of rare-earth PM materials, their costs are steadily rising. This study proposes an LHEFSM, a dual stator LHEFSM (DSLHEFSM), and a dual mover LHEFSM (DMLHEFSM) to solve this issue. The employment of ferrite magnets rather than rare-earth PM in these suggested designs is significant. Compared to traditional designs, the proposed designs feature greater thrust force, power density, reduced normal force, and a 25% decrease in PM volume. A yokeless primary structure was used in a DSLHEFSM to minimize the volume of the mover, increasing the thrust force density. In DMLHELFSM, on the other hand, a yokeless secondary structure was used to lower the secondary volume and the machine’s total cost. Single variable optimization was used to optimize all of the proposed designs. By completing a 3D study, the electromagnetic performances acquired from the 2D analysis were confirmed. Compared to conventional designs, the average thrust force in LHEFSM, DSLHEFSM, and DMLHEFSM was enhanced by 15%, 16.8%, and 15.6%, respectively. Overall, the presented machines had a high thrust force density, a high-power density, a high no-load electromotive force, and a low normal force, allowing them to be used in long-stroke applications.

Design and lumped parameter magnetic network model of hybrid excited consequent pole flux switching machine

PurposeThe purpose of this paper is to analyze electromagnetic performance and develop an analytical approach to find the suitable coil combination and no-load flux linkage of the proposed hybrid excited consequent pole flux switching machine (HECPFSM) while minimizing the drive storage and computational time which is the main problem in finite element analysis (FEA) tools.Design/methodology/approachFirst, a new HECPFSM based on conventional consequent pole flux switching permanent machine (FSPM) is proposed, and lumped parameter magnetic network model (LPMNM) is developed for the initial analysis like coil combination and no-load flux linkage. In LPMNM, all the parts of one-third machine are modeled which helps in reduction of drive storage, computational complexity and computational time without affecting the accuracy. Second, self and mutual inductance are calculated in the stator, and dq-axis inductance is calculated using park transformation in the rotor of the proposed machine. Furthermore, on-load performance analysis, like average torque, torque density and efficiency, is done by FEA.FindingsThe developed LPMNM is validated by FEA via JMAG v. 19.1. The results obtained show good agreement with an accuracy of 96.89%.Practical implicationsThe proposed HECPFSM is developed for high-speed brushless AC applications like electric vehicle (EV)/hybrid electric vehicle (HEV).Originality/valueThe proposed HECPFSM offers better flux regulation capability with enhanced electromagnetic performance as compared to conventional consequent pole FSPM. Moreover, the developed LPMNM reduces drive storage and computational time by modeling one-third of the machine.

Analysis and optimization of a five-phase hybrid excitation flux switching machine based on the consistency and complementarity principle

In this study, the general optimal stator poles/rotor teeth (P/T) combination equation of the E-core hybrid excitation flux switching (HEFS) machines are introduced, and a new HEFS machine is proposed and optimized. Firstly, the influences of three different P/T combinations (10/18, 10/19, and 10/21) on the HEFS machines are investigated with two-dimensional (2D) finite element analyses (2D-FEA). Meanwhile, the consistency and complementarity principle of the armature windings is analyzed in detail to give reasonable explanations to the simulated results. The general optimal P/T combination equation of the E-core HEFS machines is deduced mathematically to provide an effective guidance on the selection of P/T combinations. The optimal P/T combination calculated by the general equation agrees with the simulated results which confirm the correctness of the mathematical inferences. Finally, the optimizations on the proposed HEFS machine are implemented to obtain higher output torque and better flux-regulation ratio characteristics based on which the cogging torque and torque ripple are reduced significantly.

Design and optimization of segmented PM consequent pole hybrid excited flux switching machine for EV/HEV application

Hybrid Excited Flux Switching Machines (HEFSMs) unique feature of high torque density (T den ) of Permanent Magnet (PM) machines and flux regulation capability of wound field excitation machines. Due to aforesaid unique features, stator active HEFSMs are preferred for EV/HEV applications. In this paper a new Segmented PM Consequent Pole HE-FSM (sPMCPHEFSM) with flux bridge is proposed for EV/HEV. The developed SPMCPHEFSM exhibits improved flux modulation and flux regulation capability at reduced PM usage (suppressed PM volume by 46.52% and PM cost by 46.48%) and eliminating stator leakage flux. First, SPMCPHEFSM is geometric optimized (GO) for investigating influence of leading design with key performance indicators such as flux linkage (Φ pp ), average torque (T avg ), cogging torque (T cog ), T den , average power (P avg ) and power density (P den ) and then proceeded optimized model to structure modification for optimal stator design and position of field excitation coils (FEC). Comprehensive performance analysis reveals that the developed SPMCPHEFSM show improved Φ pp maximum up to 9.11%, improved T avg maximum up to 23.63%, truncate T cog up to 18.9% whereas T den and P den are boost up to 23.55% and 89.72% respectively.

Flux-Regulation Principle and Performance Analysis of a Novel Axial Partitioned Stator Hybrid-Excitation Flux-Switching Machine Using Parallel Magnetic Circuit

This article proposes a novel hybrid-excitation flux-switching (HEFS) machine with axial partitioned stator (APS) arrangement, which can achieve the independent accommodation of armature winding and field-excitation winding, thus enhancing the field-excitation capability and improving the winding heat dissipation. More importantly, a particular parallel-magnetic-circuit hybrid-excitation pattern consisting of the axial and radial magnetic paths is innovatively developed in the HEFS machine, which is an effective solution for improving the flux-regulation ability. Consequently, the PMC-based flux-regulation principle is comprehensively illustrated. Moreover, by investigating the flux-regulation characteristics of three structural feasible APS-HEFS topologies, the bilateral complementary structure is finally determined as the preferred option. By using the multiobjective optimization method and the three-dimensional finite-element analysis (FEA), the dimensional parameter optimization design of the proposed machine is conducted, and the performance comparison with conventional HEFS counterparts is also carried out to prove the flux-regulation superiority of the proposed design. Finally, a prototype is fabricated for experimental testing, and the measured results are in good agreement with the FEA, which verifies the validity of the proposed APS-HEFS topology and its theoretical flux-regulation principle analysis.

Design and performance analysis of various high torque segmented rotor HE‐FSM topologies for aircraft applications

Electrical machines for aircraft applications require basic characteristics such as lightweight, high reliability, fault tolerance ability, and torque power and higher densities. Correspondingly, hybrid excitation flux switching machines (HE-FSMs) are capable of producing significant characteristics of high torque and power by improving flux strengthening in the iron core. However, magnetic flux cancellation and leakage in HE-FSMs cause the reduction of flux linkage created by permanent magnet (PM) and field excitation (FE), which leads to deterioration of electromagnetic torque. This study presents magnetic flux performance and comparison of various topologies of HE-FSMs by employing different positions of PMs and FE coils on the stator core. The purpose of a segmented rotor is to deliver a well-defined electromagnetic flux pathway for carrying magnetic flux to nearby armature coil on stator with rotor rotation to improve the flux strengthening. Moreover, magnetic performances of various proposed HE-FSMs at different positions of PMs are investigated and compared based on 2D finite element analysis. Subsequently, the enhanced HE-FSM III has successfully achieved flux strengthening of 22%, torque of 54% and power of 61% more than initial design of HE FSM I, respectively. In conclusion, the proposed HE-FSM structures show the capability to match high torque and power for aircraft applications.

A New Outer-Rotor Hybrid-Excited Flux-Switching Machine Employing the HTS Homopolar Topology

Currently, studies of flux switching machines are actively underway owing to several advantages of these machines, including their sturdy rotor structure and high output capability. This paper deals with an outer-rotor hybrid-excited flux-switching machine (FSM). The proposed machine embraces a homopolar structure and utilizes permanent magnets (PMs) for field excitation and a high-temperature superconducting (HTS) coil for flux regulation. The stator houses the HTS field coil, PMs, and armature windings. The outer rotor consists solely of an iron core. Thus, the machines are cost effective and can serve as a solution to the design and fabrication complexities of field current supplying and cooling systems. In this paper, the machine performance outcomes are analyzed using the 3D finite element method (FEM), and the validity of the proposed machine is verified.

Maximum Ratio of Torque to Copper Loss Control for Hybrid Excited Flux-Switching Machine in Whole Speed Range

This paper proposes an optimized control strategy for hybrid excited flux-switching machine (HEFSM) in the whole speed range. First, the machine topology, operating principle, electromagnetic performance, and dynamic models of HEFSM are briefly introduced. Second, in the constant torque range, the optimized positive excitation is utilized to improve the load capacity, and minimize the copper loss, as well as achieve a faster response than the strategy of random combination of excitation and armature current and the zero excitation current control. In constant power range, there are several constraints like torque, current, voltage and speed. The optimized negative excitation current and d -axis current are not only used to achieve higher speed and produce reluctance torque, but also minimize the copper loss for a certain value of torque in the optimized strategy. Then, the maximum ratio of torque to copper loss is realized. Finally, other losses (such as iron loss, friction, and windage losses) and efficiency of HEFSM are analyzed. The feasibility and effectiveness of the proposed control strategy for the HEFSM drive system are confirmed by simulation and experiment.

Performance Analysis of Novel Single-Phase Parallel Hybrid-Excited Flux-Switching Machine

To obtain magnetic field regulation capacity and reduce copper loss in the field winding, a single-phase parallel hybrid-excited flux-switching machine (PHEFSM) is investigated in this paper. Because the permanent magnet with tangential magnetization is fixed at the slot opening of the field winding slot, the yoke width of the field winding slot determines the magnetic field regulation capacity, and the saturation condition varies significantly with the field current. To accurately calculate the performance of PHEFSM, a nonlinear magnetic equivalent circuit model that considers the iron saturation is derived, and it is verified by the finite-element method. A composite rotor with two kinds of rotor core laminations is adopted to obtain self-starting capability. Two prototype machines with a classical rotor and a composite rotor are produced and tested to verify the conclusions.

Preliminary studies of 12S-8P and 12S-14P Hybrid-Excited Flux Switching Machine with FEC in radial direction by using JMAG-designer software

In this paper, design analysis of Hybrid- Excited Flux Switching Machine (H-EFSM) with 12Slot-8Pole (12S-8P) and 12Slot-14Pole (12S-14P) topologies are presented. H-EFSM has been introduced in which the advantage of Permanent Magnet (PM) machines and DC Field Excitation Coil (FEC) synchronous machines is combined. H-EFSM design proposed less permanent magnet consumption, high to torque/power density and high efficiency. In recent, most of H-EFSM having FEC arranged in theta direction that affect in flux production which cause less flux generation and machines performances. Therefore, a design of 12S-8P and 12S-14P H-EFSM with FEC arranged in radial direction is proposed to prevent flux cancellation and produce high flux linkage. Performance analysis of 12S-8P and 12S-14 H-EFSM such as PM flux, induced voltage, cogging torque and flux distribution are investigated by 2-D Finite Element Analysis (2D-FEA). A design with 12S-14P configuration has achieved the higher torque and power with 220.15Nm and 92.45kW, respectively at maximum field and armature current density

Quantitative Evaluation of the Topologies and Electromagnetic Performances of Dual-Three-Phase Flux-Switching Machines

Hybrid-excited flux-switching machines based on permanent magnet (PM) flux-switching machines were proposed to achieve improved torque–speed characteristics. However, due to the reduction of PM volume, decreases in torque density and efficiency are usually inevitable. Thus, it is necessary to make a comprehensive comparison between the dual-three-phase hybrid-excited flux-switching machines and their PM flux-switching counterparts. To obtain a full understanding of flux-switching machines, PM flux-switching machines with U-shaped stator cores and alternate-pole magnets or C-shaped stator cores are considered. From the perspective of the frequency domain, this paper not only gives a comprehensive evaluation and comparison of the above-mentioned six flux-switching machines, but also reveals the theoretical mechanism that results in their different electromagnetic behavior in a unified way by the general field modulation theory, which is the main contribution of this paper.

Comparative Investigation of Hybrid Excitation Flux Switching Machines

In this paper, the effect of partitioned stator (PS) structure and iron flux bridges in hybrid excitation flux switching (HEFS) machines is comprehensively discussed and compared. Firstly, the operating principles of four HEFS machines with single stator and PS respectively with and without iron flux bridges are described. Then an equivalent lumped parameter magnetic circuit model is developed to analyze the characteristics of PS structure and iron flux bridges. In order to achieve a fair comparison among different HEFS machines, the multi-level design optimization method is used to obtain the optimal parameters efficiently, based on which the electromagnetic performances of four machines are comprehensively evaluated by using 2D finite element analysis (2D-FEA). The results reveal that the machines with PS structure can exhibit not only a better flux regulation capability but also a higher torque density than conventional HEFS machines. Moreover, by adopting iron flux bridges, enlarged wide constant power speed region (CPSR) can be achieved, but the PM utilization will be slightly sacrificed.

Preliminary Design Investigation of Dual Stator HE FSM using Segmental Rotor

To drop the effect of air transportation on the atmosphere as well as to advance fuel productivity more-electric aircraft (MEA) architectures is a well-known approach. As the electrical machines are competent to deliver higher torque densities and are foremost for the viability of electrical driving force for aircraft applications. For these reasons a new category of machine has been familiar and published in last decade known as flux switching machine (FSM). FSMs comprises all excitation sources on stator side without winding robust rotor structure. Additionally, FSMs are classified into three types such as permanent magnet (PM) FSMs, field excitation (FE) FSMs and hybrid excitation (HE) FSMs. PM FSM and FE FSM use PM and FE coil for their excitation sources respectively, whereas both PM and FE coil are used in HE-FSM for excitation. Afterwards, HE FSMs have shown higher torque to weight ratios with higher efficiency during research in the last decade. Yet, in existing structures of HE FSMs, there is flux cancellation between the fluxes of PMs and FE coil which causes to reduce the performance of machines. Hence, in this paper, a novel structure of dual stator (DS) HE FSM with segmented rotor has been proposed and analyzed. The main reason of dual stator is to make the separate flow fluxes in HE machines to avoid cancellations. The proposed novel DS HE FSM has a simple structure using dual stators to endorse separate dual excitations to be used in fault conditions. The proposed structure has been analyzed using commercial 2D FEA package, JMAG-designer. Initially, this paper presents the coil test analysis of proposed DS HE FSM to confirm the working principle. Besides, performance analysis has been carried out at no load and load conditions.

Performance Analysis of 12Slot with Various Rotor Pole Numbers HE-FSM for HEV Application

This paper presents performance analysis of 12Slot with various rotor pole numbers Hybrid Excitation Flux Switching Machine (HEFSM) for Hybrid Electric Vehicles (HEVs) application. HEFSM has carried out by combining the advantage of Permanent Magnet (PM) machines and DC Field Excitation Coil (FEC) synchronous machines. Previously, most of HEFSM structure having FEC windings in theta direction that create a problem of flux cancellation that will affect the performances of the machine. Thus, a design of 12Slot HEFSM with FEC wounded in radial direction is proposed to eliminate the flux cancellation effect. At first, armature coil arrangement test at no-load condition is conducted to analyze PM flux. Furthermore, induced voltage and cogging torque at open circuit condition are investigated based on 2D finite element analysis (FEA). Finally, torque and power performances are also examined at maximum FEC and armature current densities. The outcomes demonstrate that 12S-14P configuration has the highest PM flux linkage, torque, power and less distortion of back-emf waveform which are required to be used as a motor in HEVs. The highest torque and power achieved are 220.15Nm and 92.45kW, respectively.

Design Optimization of a Hybrid-Excited Flux-Switching Machine for Aircraft-Safe DC Power Generation Using a Diode Bridge Rectifier

This paper presents a design optimization methodology of a hybrid-excited flux-switching machine (HEFSM) for aircraft dc power generation. Hybrid machines are favored in new aircraft embedded generation systems because of their high power density. Their flux control capability allows the use of the more reliable diode bridge rectifier and makes them suitable for wide-speed-range dc power generation. However, in order to respect aviation safety requirements, these machines must have a limited remanent voltage, and, therefore, an optimal design is needed. At first, the electromagnetic performances of the HEFSM are studied using a transient finite-element model. In order to perform design optimization, a static method is used instead. This method is shown to be much less time consuming and more suitable for optimization routines. The results have shown very promising performances of the new design. Despite having a very small remanent voltage, high power density has still been achieved.

An Analysis of Iron Flux Bridges Topologies for 12Slot-14Pole HE-FSM

In this paper, a novel Hybrid Excitation Flux Switching Machine (HE-FSM) with DC-field excitation coil (DC-FEC) wounded in radial direction is proposed. The design is able to generate high torque and power performance because of a few points of interest such as robust rotor structure, non-overlapping windings and reduction of flux cancellation in stator yoke. However, the design with FEC in radial direction required no space between upper FEC and outer stator of machine which is lead to flux loss to surrounding area and flux saturation in stator yoke. As a solution, iron flux bridges have been introduced on the stator core to produce high torque execution. By using JMAG Designer ver. 14, numerous configuration of iron flux bridges have been presented and overviewed. Then, performances of torque at numerous flux bridges is analysed and compared. A design with highest torque is chosen to investigate the other performances of the machine.

Investigation of a Five-Phase E-Core Hybrid-Excitation Flux-Switching Machine for EV and HEV Applications

In this paper, to improve flux-regulation and constant-power speed range, a 10-stator-pole/18-rotor-pole five-phase hybrid-excitation flux-switching (HEFS) machine with “E”-core stator cell is proposed and analyzed. The topology and operation principle are investigated first. Then, the different armature winding connection methods are evaluated to reduce the total harmonic distortions of phase permanent magnet (PM) flux linkages. Furthermore, based on a simplified magnetic circuit, the analytical power-sizing equations are derived to determine the main design dimensions and parameters of E-core HEFS machines with given performance specifications. The electromagnetic performance, including the conventional static characteristics, such as phase PM flux, back electro-motive-force, cogging torque, electromagnetic torque, and flux-regulation capability, is analyzed by means of two-dimensional (2-D) and 3-D finite-element analysis to take end effect into account. The predicted results indicate that the proposed five-phase E-core HEFS machine exhibits improved flux-regulation capacity and wide range of speed regulation. The performances of HEFS machine are verified by experimental results on a prototype machine. Therefore, the HEFS machine is a promising candidate for electric vehicle and hybrid electric vehicle applications especially for direct-driven systems where the wide range of speed regulation and high-efficiency performance are crucial.