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Electromagnetic Performance Prediction of a Double-Rotor Flux-Switching Motor Based on General Air-Gap Equivalent Algorithms Model
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In this study, a new sensitivity analysis based on non-linear varying-network magnetic circuit (VNMC) method is proposed for an outer-rotor I-shaped permanent magnet flux-switching motor. By integrating concept of sensitivity analysis into the non-linear VNMC method, the whole design efficiency can be improved effectively by using the comprehensive sensitivity method and sequential non-linear programming algorithm. In the optimisation process, two design objectives are selected, including machine output torque and torque ripple. Based on the sensitivity analysis, the parameters possessing the significant influence on the design objectives can be selected purposely, thus the overall amount of calculation is obviously reduced. After the determination of the sensitive parameters, the rest of optimisation can be realised efficiently by the non-linear VNMC method. Finally, a prototype motor is manufactured and tested. Both theoretical analysis and experimental results confirm the effectiveness of the proposed method.
This paper proposed to implement a segmented-rotor high temperature superconducting (HTS) flux-switching (HTS-FS) generator with dual electrical ports for offshore wind power generation. The originality is both electrical ports, namely armature windings and field-excitation windings, are placed in the stator so that the stationary seal of the cryogenic cooling system can be achieved. The key lies in that the HTS field-excitation windings in the stator side provide high field excitation, and the sinusoidal electromotive force (EMF) in armature windings is induced by the magnetic field modulation of the segmented rotor. A new kind of racetrack-shaped Dewar with vacuum-sandwich was proposed and fabricated to accommodate and cool the HTS coils. Based on this proposed racetrack-shaped Dewar, a cryogenic cooling system of the proposed generator was established to maintain the superconducting properties of HTS wires. Both finite element analysis (FEA) and experiments were carried out to verify the validity of the proposed generator and its cryogenic cooling system. Index Terms-Cryogenic cooling system, finite-element analysis, flux-switching, high temperature superconducting, racetrack-shaped Dewar, stationary seal.
Motors that convert electrical energy to mechanical energy, have been considered as one of the most crucial components of all-climatic electric vehicles (EVs). In order to realize high-quality energy conversion, motor optimization has attracted considerable attention in the research field of motors. In this paper, systematic multi-level optimization design and dynamic control strategy is proposed for a less-rare-earth hybrid permanent magnet (LRE-HPM) motor. In the proposed systematic optimization strategy, the design requirements of the motor design level and control level are considered comprehensively. In the motor design level, the comprehensive sensitivity analysis is adopted to stratify design parameters, and the response surface method and multi-objective genetic algorithm are implemented respectively. In the motor control level, the resonance compensation strategy is established to further suppress torque ripple and speed vibration. Finally, a prototype motor is built and tested. Both simulation and experimental results not only verify the effectiveness of the proposed systematic optimization and dynamic control strategy, but also offer a research orientation for realizing high-quality energy conversion of all-climatic EVs.
In this paper, an airgap-harmonic-orientated design method is proposed, where the airgap harmonics are newly acted as the effective bridge between the three key elements of permanent magnet sources, modulators, or armature windings and the motor performances. And in the proposed design method, the airgap harmonics play couple of roles of design objectives and variables, which are not only served as the design variables for the motor performances, but also considered as the objectives for design parameters. For extensive investigation, a V-shape flux-modulated permanent-magnet (V-FMPM) motor is selected as a design example, which has a potential application for the electrical vehicles. In the optimization process, the sensitivity analysis of different airgap harmonics on the torque performance is conducted to select the leading airgap harmonics. Meanwhile, the sensitivity degrees of the design parameters on the leading harmonics are calculated to pick out the sensitive design parameters. Then, the performances of the V-FMPM motor are evaluated for validating airgap-harmonic-orientated design method. Finally, a prototype motor is built and tested. Both the theoretical analysis and experimental results verify the effectiveness and reasonability of the proposed design method and the V-FMPM motor.
This paper proposes a novel high-temperature super-conducting (HTS) claw-pole vernier machine, which combines the merits of stator HTS-excitation machine with the “magnetic gearing effect” designed for direct-drive applications. The key is to adopt claw-pole stator structure to realize the multi-pole pattern using single HTS-excitation unit with stationary seal, thus greatly simplifying the cooling Dewar architecture as well as improving the structural compactness. Moreover, the armature windings are wound around the split-teeth which are set on the surface of claw poles to achieve the physical separation from the HTS-excitation coil, thus reducing their space conflicts and impact with each other. The operation principle analysis and the initial machine design are conducted in details. By using the three-dimensional finite element analysis, the machine performances are evaluated, and its validity is verified.
Permanent magnet Vernier (PMV) machines have attracted more and more attention for their merits of high torque density and simple structure. And principle of electromechanical energy conversion is the most common way to investigate the PMV machine by calculating back EMF and electromagnetic torque. In this paper, a new perspective on the mechanism of PMV machines based on the Maxwell stress tensor method is presented to deepen the insight into the reason why the force on the rotor of a PMV machine is larger than that of a SPM machine. Based on the FEA method, three machines with exactly the same rotor are analyzed and compared, namely, 24-slot/20-pole SPM, 12-slot/20-pole surface PMV and 6-slot/20-pole split-tooth PMV machines. The radial and tangential flux density and force distributions along the airgap are illustrated. The influence of pole ratio on the performance of PMV machines is also investigated. It is shown that the improvement of tangential flux density in the PMV machine plays a primary role in the higher torque density, which shows a promising way to improve the torque density of machines.
In this paper, two permanent magnet flux-intensifying motors are designed and optimized to realize the characteristic of
L<sub>d</sub>
>
L<sub>q</sub>
and the flux-intensifying effect. Compared with the conventional interior permanent magnet motor with the characteristic of
L<sub>d</sub>< L<sub>q</sub>
, the advantages of a low irreversible demagnetization risk and a wide speed range can be obtained in the motors. To meet multiple design requirements effectively, a comprehensive sensitivity analysis method is first implemented to evaluate the influence of each design variable on the selected optimized objectives of output torque, reverse saliency ratio, and torque ripple. Second, a sequential nonlinear programming algorithm is used for realizing the multiobjective optimizations of strong-sensitive design variables. Then, the performances of the two optimal motors are analyzed and compared with the initial permanent magnet motor in detail. Finally, two prototype motors are manufactured and tested. Both the simulation and experimental results verify the validity of the new flux-intensifying motors and the optimization method.
In this paper, the memory flux principle is extended to switched flux structures, forming two newly emerged switched flux memory machines (SFMMs) with single-stator (SS) and dual-stator (DS) configurations. Two types of permanent magnets (PMs), i.e., NdFeB and low coercive force (LCF) PMs, are located in the stationary part. Thus, the developed machines can achieve easy online PM magnetization control, excellent air-gap flux control, and acceptable torque capability. In order to address the issue about the limited stator space encompassing dual PMs and magnetizing coils in the SS-SFMM, a DS design is further developed, where all excitations are placed on a separate inner stator to improve the torque density. A comparative study between the SFMMs with SS and DS structures is established. The investigated machine topologies and operating principle are described first based on a "U"-shaped hybrid PM arrangement, and the PM sizing of the DS machine is optimized with a simplified magnetic circuit model. In addition, the electromagnetic characteristics of the SFMMs with SS and DS structures are investigated and compared by finite-element (FE) method. The FE results are validated by the experiments on two fabricated prototypes. IEEE
In this paper, a multi-mode design method is proposed for motor design under multiple operation conditions. Based on the driving cycles in electric vehicles, five typical operation conditions and the corresponding five driving modes are determined for the multi-mode design. To investigate the method conveniently, a flux controllable stator permanent magnet memory motor is selected and taken as a design example. In the design process, by using the sensitivity analysis method, the parameters significances in various driving modes are evaluated effectively. Based on the motor driving demands, the whole optimization design is divided into three steps, where different optimization method is applied in each step. To verify the feasibility of the multi-mode design method, the operation performances of the motor in different driving modes are investigated in detail. Finally, a prototype motor is built and tested. Both the simulation and experimental results reveal that the proposed design method can offer an effective design optimization for the FC-SPM memory motor, where multi-mode operations are indispensable.
PM-assisted claw-pole synchronous motor (CPSM) has commonly been used in a variety of industrial applications, thanks to its robust structure and high energy density. However, such motor has an axially asymmetric rotor configuration, which induces the corresponding 3-D magnetic field distribution. Thus, this paper proposes an infinitesimal hexahedron-element-based 3-D equivalent magnetic circuit network (EMCN) method in order to estimate the performance of the PM-assisted CPSM. The hexahedron element is considered as an optimum unit element in describing the configuration of the PM-assisted CPSM in detail. That eventually makes it possible to evaluate the specific 3-D magnetic field distribution from which the flux linkage, the back electro-motive force, and the torque are also being calculated. The 3-D EMCN results are compared with 3-D FEA data and/or experimental data to validate their accuracy. Finally, it is proved that the scalar-potential-based 3-D EMCN method requires less computing time than the vector-potential-based 3-D FEA.
In recent years, permanent magnet (PM) vernier machines have gained more and more attentions due to their high torque density and simple mechanical structure. However, vernier PM machines with lap windings always suffer from long end winding length, and regular non-overlapping winding may result in torque reduction for PM vernier (PMV) machines. In this paper, an advanced PM vernier (APMV) machine topology with multi working harmonics is proposed. With specially designed stator auxiliary teeth, this topology could achieve ~20% higher torque density than that of regular non-overlapping winding PMV machine, with the same magnet usage. Through finite element algorithm (FEA) and theoretical analysis, the production of additional flux density harmonics and their contributions to back-EMF are verified. Moreover, the electromagnetic performances of this novel machine topology, such as back-EMF and output torque are quantitatively investigated, with the geometric parameters' effect considered. Finally, analysis results are verified by experimental test on a 21Nm prototype, which is designed to have similar volume and weight with a 14Nm regular commercial PM machine.
In this paper, an outer rotor flux-switching permanent magnet motor incorporating the concept of stator permanent magnet motor into outer-rotor motor is investigated. Similar to the traditional flux switching permanent magnet motors, the torque ripple of the motor is relatively high. In order to realize the torque ripple reduction effectively, a new systematic multi-level design and control scheme is proposed to co-reduce the torque ripple of the proposed motor. In motor design level, by adopting the design of experiments method and the response surface method, the lower cogging torque with desirable high output torque and efficiency can be obtained. In motor control level, the optimization model based on the iterative learning control method is proposed, where the optimal compensating torque can be produced to further suppress the torque ripple. Finally, a prototype motor is manufactured for evaluation. Both simulation and experiment results verify the validity of the proposed method.
In order to optimize the current-control performance of the permanent-magnet synchronous motor (PMSM) system with model parameter mismatch and one-step control delay, an improved deadbeat predictive current control (DPCC) algorithm for the PMSM drive systems is proposed in this paper. First, the performance of the conventional predictive current control, when parameter mismatch exist, is analyzed, and then a stator current and disturbance observer (SCDO) based on sliding-mode exponential reaching law, which is able to simultaneously predict future value of stator current and track system disturbance caused by parameter mismatch in real time, is proposed. Based on this SCDO, prediction currents are used for replacing the sampled current in DPCC to compensate one-step delay, and estimated parameter disturbances are considered as the feedforward value to compensate the voltage reference calculated by deadbeat predictive current controller. Thus, a composite control method combining the DPCC part and current prediction and feedforward compensation part based on SCDO, called DPCC+ SCDO method, is developed. Moreover, based on conventional exponential reaching law, a novel sliding-mode exponential reaching law is proposed to further improve the performance of the DPCC + SCDO method. Simulation and experimental results both show the validity of the proposed current control approach.
This paper proposes a brushless double mechanical port flux-switching permanent-magnet motor for potential application in hybrid electric vehicles. To realize the design objectives of high-torque capability, low-torque ripple, and low-magnetic coupling between the inner and outer motors, a new multilevel design optimization method is proposed to conduct a multiobjectives optimization. First, by adopting the comprehensive sensitivity approach, the whole optimization design process is divided into three levels: nonsensitive level, mild-sensitive level, and strong-sensitive level. Then, to improve the whole design efficiency, the response surface method and multiobjective genetic algorithm are applied in the mild-sensitive level and strong-sensitive level, respectively. Based on the proposed design method, a compromise design among the three design objectives is considered and realized. Finally, a prototype motor is built to verify the validity of the proposed design method and motor operation.
This paper proposes a new brushless double mechanical ports permanent magnet (BDMP-FSPM) motor for plug-in hybrid electric vehicles (PHEVs) applications. The key is to highly integrate two rotors and single stator into one motor frame, which based on the concept of incorporating the double rotor motor into a stator-permanent-magnet motor. In addition, by combining the non-contact magnetic planetary gear (NC-MPG) with the proposed motor, the new resulting electric continuous variable transmission (E-CVT) system can not only realize the required speed and torque transmission, but also manage the power split and combination in various driving cycles. The electromagnetic performances of the proposed motor are analyzed by using the finite-element method, such as magnetic field distribution, coupled back-EMF, torque performances, torque-speed curves and power-speed curves. Experimental results of the BDMP-FSPM prototype are also given to verify the validity.
In this paper, a nonlinear magnetic network model (NMNM) is proposed to predict the electromagnetic performance of a hybrid-excitation flux-switching (HEFS) machine, in which the modeling of the magnetic motive forces (MMF) due to field windings is specifically investigated. The proposed NMNM enables the predictions of air-gap flux-density distributions, flux linkage, back-electromotive force (back-EMF), and inductances of both armature and field windings under different excitation conditions, including pure magnets, pure field currents, and hybrid excitations. The predicted results from the NMNM model are validated by 2-D finite element analysis. Index Terms—Brushless machine, finite element analysis, flux-switching, hybrid excitation, magnetic network model, nonlinear.
Permanent magnet (PM) brushless machines having magnets and windings in stator (the so-called stator-PM machines) have attracted more and more attention in the past decade due to its definite advantages of robust structure, high power density, high efficiency, etc. In this paper, an overview of the stator-PM machine is presented, with particular emphasis on concepts, operation principles, machine topologies, electromagnetic performance, and control strategies. Both brushless ac and dc operation modes are described. The key features of the machines, including the merits and drawbacks of the machines, are summarized. Moreover, the latest development of the machines is also discussed.
A nonlinear adaptive lumped parameter magnetic circuit model is developed to predict the electromagnetic performance of a flux-switching permanent-magnet machine. It enables the air-gap field distribution, the back-electromotive force (back-EMF) waveform, the winding inductances, and the electromagnetic torque to be calculated. Results from the model are compared with finite-element predictions and validated experimentally. The influence of end effects is also investigated, and optimal design parameters, such as the rotor pole width, the stator tooth width, and the ratio of the inner to outer diameter of the stator, are discussed.
Multilevel design optimization and operation of a brushless double mechanical port flux-switching permanent-magnet motor
- X Zhu
- Z Shu
- L Quan
- Z Xiang
- X Pan
A novel mesh-based equivalent magnetic network for performance analysis and optimal design of permanent magnet machines
- X Zhu
- Y Jian
- Z Xiang
Comprehensive sensitivity analysis and multi-objective optimization Multimode optimization design methodology for a flux-controllable stator permanent magnet memory motor considering driving cycles on research of permanent magnet flux-intensifying motors
- X Zhu
- J Huang
- L Quan
- Z Xiang
- B Shi