Hybrid Excitation Flux Switching Motor Research Articles

Comparative Study on Hybrid Excitation Flux Switching Motors without and with Variably Magnetizable Permanent Magnets for Electrified Vehicle Propulsion

A demand for high efficiency traction motors has been accelerated by the promotion of electrified vehicles, such as battery and fuel cell electric vehicles. As a part of development of the high efficiency traction motor, this paper reports a comparative study on two kinds of hybrid excitation flux switching motors (HEFSM) as a variable flux machine. One is the conventional HEFSM, which consists of a stator with constantly magnetized-permanent magnets, field excitation coils (FECs) and three-phase armature windings, and a rotor with salient poles like a switched reluctance motor. The other is a HEFSM employing variably magnetizable-permanent magnets (VM-PMs) that replace a part in the FEC slot area in the conventional one. Based on the variable magnetization nature of VM-PMs, the latter HEFSM promises that the replacement of magnetomotive force (mmf) of FECs with that of the VM-PMs makes the motor efficiency better at both low- and high-speed under the low-torque condition, that is, at both urban driving or highway cruising. To verify that, finite element analysis- (FEA)-based design simulations, as well as experimental performance evaluations for the two kinds of HEFSM, were conducted under reasonable dimensional and electrical constraints. As a result, it is shown that the latter HEFSM can achieve higher motor efficiency at the low-torque and high-speed region while keeping the motor efficiency at the low-torque and low-speed region.

An On-Board Two-Stage Integrated Fast Battery Charger for EVs Based on a Five-Phase Hybrid-Excitation Flux-Switching Machine

In this article, to solve the existing problems in general on-board integrated chargers, a novel three-phase on-board two-stage integrated charger is proposed by taking the unique advantages of a five-phase hybrid-excitation flux-switching (HEFS) motor. The general topologies and newly presented integrated chargers are reviewed first, and existing problems are concluded. Then, a two-stage integrated charger is proposed, and all winding selections are thoroughly investigated by theoretical analysis, finite-element analysis (FEA), and experiments. In the proposed topology, the existing problems are all solved by employing this multiphase system, reasonable winding selection, and reconfiguring the field winding. After that, a current balance control method for charge mode without a phase-locked loop circuit is presented. The simulation results verify the effectiveness of the proposed control methods. Finally, based on a 5-kW five-phase HEFS prototype machine and two sets of the three-phase generic motor controller, an experiment platform is built. The experiment results agree well with the simulation results. Therefore, the feasibility of a two-stage integrated on-board charger that can operate at any voltage level is confirmed, where only the hybrid-exciting machine and its driving system are used without any additional power devices.

A Single-Phase On-Board Two-Stage Integrated Battery Charger for EVs Based on a Five-Phase Hybrid-Excitation Flux-Switching Machine

In this paper, to solve the existing problems in general on-board integrated chargers (IC), a novel single-phase on-board two-stage integrated charger is proposed by taking the unique advantages of the five-phase hybrid-excitation flux-switching (HEFS) motors. The general topologies and newly presented ICs are reviewed firstly, and three main problems are concluded. Then, the proposed two-stage IC is presented, and all winding selections are thoroughly investigated by theoretical analysis, finite-element analysis (FEA) and experiments. In the proposed topology, the existing problems are all solved by employing this multi-phase system, making the reasonable winding selection, and reconfiguring the field winding. After that, a control method for charge mode and two current balance control methods are developed. The simulation results verify the effectiveness of the proposed control methods. Finally, based on a 5-kW five-phase HEFS prototype machine and two sets of the 3-phase generic motor controller, an experiment platform is built. The experiment results agree well with the simulation results. Therefore, the feasibility of a two-stage integrated on-board charger that can operate at any voltage level is confirmed, where only the hybrid-exciting machine and its own driving system are used without any additional power devices.

Hybrid excitation flux switching motor with permanent magnet placed at middle of field coil slots and high filling factor windings

Design and experimental studies on a hybrid excitation flux switching motor as a traction motor for hybrid electric vehicles drive are presented. A stator body of the motor consists of not only laminated silicon-iron electromagnetic steel and three-phase armature windings, but also both of field excitation coils and permanent magnets working together as a variable field magnetomotive force source. On the other hand, a rotor is composed of just laminated silicon-iron electromagnetic steel with salient poles like switched reluctance motor. To bring out the best in drive performances of the hybrid excitation flux switching motor as a variable flux motor for the application, each material adopted for the stator and rotor body should be designed properly in terms of motor efficiency, maximum torque and power densities and so forth. As some of them, in this paper, thinner silicon-iron electromagnetic steel sheet and permanent magnets with high remanent and low amount of Dysprosium used are applied for achieving higher motor efficiency. Moreover, all coils wound flatwise and edgewise using rectangular wires are introduced to realizing high filling factor for reduced copper losses. Experimental tests using a 60kW prototype of the motor demonstrates the designed motor has good motor efficiency under frequent operating points expected for the target vehicle drive.

Cyclic Parameter Refinement of 4S-10 Hybrid Flux-Switching Motor for Lightweight Electric Vehicle

A great deal of attention has been given to the reduction of lighting the vehicle because the lighter the vehicle the energy consumption is comparatively low. Hence, the lightweight electric vehicle was introduced for lower carbon footprint and the sizing of the vehicle itself. One of the components to reduce the weight of the vehicle is the propulsion system which comprised of electric motor functioning as the source of torque to drive the propulsion system of the machine. This paper presents the refinement methodology for the optimized design of the 4S-10P E-Core hybrid excitation flux switching motor. The purpose of the refinement methodology is to improve the torque production of the optimized motor. The result of the successful improvement of the torque production is justifiable for a lightweight electric vehicle to drive the propulsion system.

Analysis of Permanent Magnet Demagnetization Effect Outer-rotor Hybrid Excitation Flux Switching Motor

This paper addresses the irreversible permanent magnet (PM) demagnetization analysis of hybrid excitation flux switching motor (HEFSM) with outer-rotor configuration. PM demagnetization cause the PM strength used in the motor significantly reduces and hence contributes less torque performance. The study is focused on thermal analysis and conducted at various temperature up to as high as 180 degrees Celsius which has a tendency to be demagnetized. Therefore, PM demagnetization is among a critical issue and influences the choice of the applied motor. The analysis is carried out based on finite element method (FEM) and percentage of PM demagnetization is then calculated. Finally, based on simulated and calculated results the final design outer-rotor HEFSM has only 0.85 percent PM demagnetization at very high temperature and obviously the is no PM demagnetization at normal operating conditions.

Improved Design of Three Phase Hybrid Excitation Flux Switching Motor with Segmental Rotor

This paper presents the new design of Hybrid Excitation Flux Switching Motor (HEFSM) using segmental rotor structure. HEFSMs are those that consist all the excitation flux sources at their stator with robust rotor structure. The rotor is designed as segmental due to the reason that segmental rotor has ability to yield the magnetic path for conveying the field flux to nearby stator armature coil with respect to the rotation of the rotor. This design gives the clear advantage of shorter end winding compared to the toothed rotor as there is no overlap winding between field excitation coil (FEC) and armature coil. In this paper the initial design of HEFSM with segmental rotor has been improved by changing segment span, FEC slot area and armature slot area until maximum torque and power of 33.633 Nm and 8.17 KW respectively have been achieved. Moreover coil test analysis, induced voltage, cogging torque, magnetic flux characteristics, torque vs. field current density and torque vs. power speed characteristics are examined on the basis of 2-D finite element analysis (FEA).

Performance Comparison and Analysis of (HEFSM) and (FEFSM) Using Segmental Rotor Structure

This paper presents a new structure of hybrid excitation flux switching motor (HEFSM) using segmental rotor and the comparison of HEFSM and FEFSM using segmental rotor is performed to find the best candidate for hybrid electric vehicles (HEV). (HEFSM) using segmental rotor contains both the FEC and PM on the stator to produce maximum flux linkages. Initially, the coil arrangement tests are examined to validate the operating principle of the (HEFSM) using segmental rotor. Moreover the profile of flux linkage, cogging torque, and torque characteristics at various armature current densities of both the (HEFSM) and (FEFSM) using segmental rotor are observed based on 2D-finite element analysis (FEA). Initially performances show that HEFSM using segmental rotor produces torque of 18 Nm with low cogging torque and sinusoidal flux waveform. Thus by further design optimization the proposed motor will effectively achieve the target performances.

Optimization of 6S-14P E-Core Hybrid Excitation Flux Switching Motor for Hybrid Electric Vehicle

Research on hybrid electric vehicle (HEV) which combined battery based electric motor and conventional internal combustion engine (ICE) have been intensively increased since the last decade due to their promising solution that can reduce global warming. Some examples of electric motors designed for HEV propulsion system at present are dc motor, induction motor (IM), interior permanent magnet synchronous motor (IPMSM) and switched reluctance motor (SRM). Although IPMSMs are considered to be one of the successful electric motor used in HEVs, several limitations such as distributed armature windings, un-control permanent magnet (PM) flux and higher rotor mechanical stress should be resolved. In this paper, design improvement of E-Core hybrid excitation flux switching motor (HEFSM) for hybrid electric vehicles (HEVs) applications are presented. With concentrated armature and field excitation coil (FEC) windings, variable flux capability and robust rotor structure, performances of initial and improved 6S-14PE-Core HEFSM are analyzed. The improved topology has achieved highest torque and power of 246.557Nm and 187.302 kW, respectively.

Design Optimization of Single-Phase Outer-Rotor 8S-8P Hybrid Excitation Flux Switching Motor for Electric Vehicle

Nowadays, in-wheel motors applied in pure electric vehicles (EVs) propulsion systems have attracted great attention in advance research and development. In-wheel direct drive provides quick torque response, higher efficiency, weight reduction, and increased vehicle space. As one of alternative, a new design of outer-rotor hybrid excitation flux switching motor (ORHEFSM) for in-wheel drive EV is proposed. In this paper, the optimization design of single-phase 8S-8P outer rotor HEFSM is analysed. Open and close circuit of initial and final design is compared based on 2-D finite element analysis (FEA). The design optimization has been made on the initial design machine shows that there is great enhancement on torque and power.

Development of High Torque and High Power Density Hybrid Excitation Flux Switching Motor for Traction Drive in Hybrid Electric Vehicles

This paper presents design feasibility study and development of a new hybrid excitation flux switching motor (HEFSM) as a contender for traction drives in hybrid electric vehicles (HEVs). Initially, the motor general construction, the basic working principle and the design concept of the proposed HEFSM are outlined. Then, the initial drive performances of the proposed HEFSM are evaluated based on 2D-FEA, in which the design restrictions, specifications and target performances are similar with conventional interior permanent magnet synchronous motor (IPMSM) used in HEV. Since the initial results fail to achieve the target performances, deterministic design optimization approach is used to treat several design parameters. After several cycles of optimization, the proposed motor makes it possible to obtain the target torque and power of 333 Nm and 123 kW, respectively. In addition, due to definite advantage of robust rotor structure of HEFSM, rotor mechanical stress prediction at maximum speed of 12,400 r/min is much lower than the mechanical stress in conventional IPMSM. Finally, the maximum torque and power density of the final design HEFSM are approximately 11.41 Nm/kg and 5.55 kW/kg, respectively, which is 19.98% and 58.12% more than the torque and power density in existing IPMSM for Lexus RX400h.

Design Optimization Studies on High Torque and High Power Density Hybrid Excitation Flux Switching Motor for HEV

Abstract This paper presents design optimization studies on high torque and high power density hybrid excitation flux switching motor (HEFSM) as a candidate for traction drives in hybrid electric vehicles (HEVs). Firstly, the construction and the basic working principle of the selected HEFSM are overviewed. Then, under some design restrictions and specifications for the target HEV drives, the initial performances of the selected HEFSM are evaluated based on 2D-FEA. As the initial motor fails to achieve the target performances, design parameters are set and treated by using deterministic optimization approach. After several cycles of iteration, the target torque and power of 333Nm and 123 kW respectively, are achieved with much higher power density when compared with existing interior permanent magnet synchronous motor (IPMSM) used in HEV.

Impact of Rotor Pole Number on the Characteristics of Outer-rotor Hybrid Excitation Flux Switching Motor for In-wheel Drive EV

This paper present the impact of rotor pole number on the characteristics of outer-rotor hybrid excitation flux switching motor (ORHEFSM) for in-wheel drive electric vehicle (EV) applications. In recent years, researches on in-wheel motor for EV drivetrain system become more popular due to their several advantages of independent wheel controllability and higher efficiency. In addition, it provides more cabin space caused by elimination of mechanical transmission gears as conventionally use in the most of existing EV with single motor propulsion system configuration. Moreover, the proposed motor has single piece of rotor making the motor more robust and suitable for high speed applications. Under some design restrictions and specifications, design principles and initial performances of the proposed motor at various rotor pole numbers with 12 stator slots are demonstrated. Initially, the coil arrangement tests are examined to confirm the operating principle and polarity of each armature coil phase of the proposed motor. Furthermore, the profile of flux linkage, induced voltage, cogging torque and torque characteristics at various field excitation current density conditions are analyzed based on 2D- finite element analysis (FEA). The results obtained show that the appropriate combination of stator slot-rotor pole configurations are 12S-10P which initially provide highest torque and power density. Thus, by further design refinement and optimization it is expected that the motor will successfully achieved the target performances.

An Axial-Flux Hybrid Excitation Flux-Switching Machine

A flux switching permanent magnet (FSPM) machine has the advantage of high power density, high torque density, inherently sinusoidal back EMF, stable structure, and the disadvantage of magnetic field uncontrollable. This paper proposes a novel axial-flux hybrid excitation flux-switching (AFHEFS) motor, which offers three phase symmetrical sinusoidal flux linkage and linearly regulated electromagnetic torque as well as excellent flux regulation capability and even field elimination ability with a size ratio of 1:2 between PM stator and electrical stator. The results are validated by 3D finite element (FE) analysis.

A Novel Hybrid Excitation Flux-Switching Motor for Hybrid Vehicles

Flux-switching permanent magnet (FSPM) motor is a relatively novel brushless machine having magnets and concentrated windings in the stator instead of the conventional rotor-PM topology, which exhibits inherently sinusoidal PM flux-linkage, back-EMF waveforms and high torque capability. However, since the airgap field is produced by the stator-magnets alone, it is difficult to be regulated. Hence, a hybrid excitation method, i.e., by introducing a set of field windings into FSPM motor is employed. In this paper, a novel hybrid excitation flux-switching (HEFS) motor is proposed, in which the airgap field can be easily controlled and is favorable for hybrid vehicles. The preliminary topology, operation principle, design and static characteristics including phase flux-linkage, back-EMF waveforms under different excitations as well as cogging torque are evaluated based on finite element (FE) analysis. The results confirm the excellent field-regulation capability of a ldquoproof-of-principlerdquo HEFS motor.