Drive machines of hybrid electric vehicles (HEVs) employ axial flux permanent magnet (AFPM) motors on account of its high power density and high efficiency. The technique takes full advantage of the performance and manufacturing preponderances of soft magnetic composites (SMC). Specifically, it includes low iron consumption at high frequency and high speed, convenient machining and small relative magnetic permeability. An extra DC excitation winding is appended to the motor to conquer the drawbacks of the constant power speed ratio. It can provide an extremely wide constant power speed region, which ensures the excellent property of the machine. Finite element algorithm (FEA) is used to assess the property of axial flux hybrid excitation motor (AFHEM). Comprehensive analysis has fully indicated that larger torque density and wider speed range can be obtained by the AFHEM, which is appropriate for the application of HEV drives.

Electromagnetic Performance Analysis of an Axial Flux Hybrid Excitation Motor for HEV Drives

The multi-disc axial flux permanent magnet synchronous machine (AFPMSM) can provide high fault tolerance capability in applications requiring high reliability. Firstly, a topological structure of coreless AFPMSM is proposed, the magnetic circuit and the air-gap flux intensity are discussed in detail to improve stable operation of machine in this paper. The relationship between air-gap flux density and the parameters of rotor are clarified respectively based on finite element algorithm (FEA). Furthermore, the winding structure and power driver topology with fault tolerance are presented. And the 3D FEA analyzes the operation characteristics and stress of the machine. Finally, the prototype is manufactured. The results are demonstrated that the torque output and fault tolerance performance is better.

Design and Analysis for Multi-Disc Coreless Axial-Flux Permanent-Magnet Synchronous Machine

speed and parameters of mechanical and thermal stability of the material from which the electric machine was made. Also, a finite element study was conducted, during which a physical model of the toroidal core was developed to determine the parameters required for inclusion in the mathematical model of the simulation of the magnetic flux distribution in the stator magnetic circuit. During the simulation of the distribution of the magnetic flux in the motor by the finite element method, the value of the magnetic permeability of the material used for the manufacture of the stator was determined. As a result, conclusions are made about the possibility of designing and creating a rotating electric machine and its use in experimental electrical installations.

рішення сучасній техніці та технологіях

Cogging torque is a critical dilemma in Permanent Magnet Brushless DC (PMBLDC) motors. In medium-low power PMBLDC motors, redundant vibrations and forbidding noises arise as a result of the harmonic magnetic forces created by cogging torque. This paper introduces a simple approach for minimizing cogging torque in PMBLDC motors by applying placement irregularities in rotor magnets. An angle shift in the rotor magnets in surface-mounted PMBLDC motors helps to attain magnet displacement. This displacement imparts an asymmetrical magnet structure to the rotor. Maintaining pole arc to pole pitch ratio (L/τ) of between 0.6 and 0.8, shifting angles from 1° to 8° were considered in order to analyze the effect of the angle shift on the rotor magnets. An analytical expression was also derived for finding the shifting angle with the minimum cogging torque in the PMBLDC motor by using the Virtual Work Method (VWM). The optimization of the shifting angle with minimum cogging torque was investigated using 3D Finite Element Analysis (FEA). A comparison of the simulation and analytical results of cogging torque was carried out. It was determined that the reduction of cogging torque in the analytical results showed good agreement with the FEA analysis.

Reduction of Cogging Torque in Surface Mounted Permanent Magnet Brushless DC Motor by Adapting Rotor Magnetic Displacement

Fused filament fabrication (FFF) was used to additively manufacture (3-D print) two-prototype circuit-analog (CA) absorbers. The CA absorbers consist of a lossy frequency selective surface (FSS), substrate, and ground plane. In this article, the FSS and substrate were manufactured using two different FFF materials to make a cohesive structure manufactured during a single printing procedure. To design the CA absorbers, the complex permittivity of FFF printed polylactic acid (PLA), bronze-, brass-, copper-, and iron-powder infused PLAs, and a graphite-PLA composite was measured using a free-space materials measurement system. Out of the candidate materials measured, graphite PLA and standalone PLA were selected as the FSSs and substrates, respectively. Complex permittivity data from the selected materials were input to Computer Simulation Technology Microwave Studio so that a genetic algorithm could optimize absorber dimensions. Reflectivity of the printed absorbers was measured using a free-space measurement setup. Measured reflectivity data were compared to that from simulations. A simulated-geometric tolerance study corroborated differences noted between ideal models and measured data. The results showed that FFF techniques can be used for CA-absorber designs and that 3-D printing settings can ultimately affect absorber performance.

Additive Manufacturing of PLA-Based Microwave Circuit-Analog Absorbers

Axial-flux permanent-magnet synchronous motors (AFPMSMs) have a higher torque density than radial-flux permanent-magnet synchronous motors (RFPMSMs); therefore, AFPMSMs are widely used in high-power and high-efficiency motors. However, in the case of AFPMSMs, three-dimensional production is limited, less mass production is available, and the production unit cost is high because the shape of the motor is implemented by rolling the amorphous electrical steel sheet or molding the soft magnetic composite (SMC) to manufacture the motor. Therefore, in this paper, a 3D-printed AFPMSM is proposed, which takes high torque density including the AFPMSM shoe to mold existing SMC into shape when producing the AFPMSM using 3D printing. Further, hybrid AFPMSM, which is made by heeding, is proposed. To reduce core loss with 3D-printed AFPMSM, the core loss of the proposed hybrid AFPMSM was compared to that of the target RFPMSM in this study. The 3D-printed AFPMSM showed a 48% increase in core loss compared to the target motor. However, the proposed hybrid AFPMSM reduced the ratio of the electrical steel sheet by more than 25% compared to 3D-printed AFPMSM. The validity of the proposed model was verified using the finite element method.

Design of 3D-Printed Hybrid Axial-Flux Motor Using 3D-Printed SMC Core

This paper describes a study on the improvement of the dehydration performance of the conventional washing machine model. Recently, as interest in improving the dehydration performance of washing machines has increased, the need for a study on a high-speed electric motor has emerged. However, this conventional spoke-type PMSM has difficulty in speeding up due to the following problems. First, field weakening control is indispensable for high-speed operation of an electric motor. This control method is a big problem in causing torque drop and irreversible demagnetization of the motor. Moreover, the centrifugal force increases during high-speed operation, which adversely affects the stiffness of the motor. Therefore, in this paper, a new rotor shape of spoke-type PMSM was proposed to solve the above problem.

A Study on the Shape of the Rotor to Improve the Performance of the Spoke-Type Permanent Magnet Synchronous Motor

The spoke-type permanent magnet synchronous motor (PMSM), which is a general ferrite magnetic flux-concentrated motor, has a low portion of reluctance torque at the total torque magnitude. Therefore, as a way to increase the reluctance torque, there is a double-layer spoke-type PMSM that can maximize the difference in inductance between the d-axis and the q-axis. However, in the double-layer spoke-type PMSM, cogging torque, torque ripple, and total harmonic distortion (THD) increase with reluctance torque, which is the main cause of vibration and noise. In this paper, a method is proposed that provides the same effect as skew without dividing stages of the permanent magnet by dividing the core of the rotor into two types so that it is easy to manufacture according to the number of stages, unlike extant skew methods. Based on the method, the reduction in cogging torque and THD was verified by finite element analysis (FEA).

https://www.mdpi.com/1996-1073/14/3/610/pdf

A Study on Core Skew Considering Manufacturability of Double-Layer Spoke-Type PMSM

Axial-flux permanent magnet synchronous motors (AFPMSMs) have higher torque densities than the conventional radial-flux permanent magnet synchronous motors (RFPMSMs). However, RFPMSMs have the advantage of lower eddy current losses in the core, owing to the use of electrical steel plates that can be stacked. Therefore, most studies on reducing the eddy current losses of the extant AFPMSMs cores have been focused on reducing the eddy current loss by using a soft magnetic composite (SMC) material or rolling an amorphous electrical steel plate. The method, which is proposed for reducing the eddy current loss of AFPMSMs in this paper, utilizes 3D printing technology to insert a 3D-printed SMC core into the stator shape of a motor that generates a large amount of eddy current; it also inserts air insulation to produce the same effect as that produced by the extant RFPMSM stacking method. The eddy current loss of a stator insulation structure using the 3D-printed SMC core is compared to that of an AFPMSM using the extant SMC core, and the validity of the proposed shape is verified through finite element analysis.

Eddy Current Loss Reduction in 3D-Printed Axial Flux Motor Using 3D-Printed SMC Core

Trends of traction motor of railway vehicles have been shifted from induction motors to permanent magnet motors. Recently, studies have been conducted on dysprosium-free permanent magnets. Dysprosium is a heavy rare earth element that has a great impact on performance of motors. However, dysprosium affects the coercive force of a permanent magnet and can produce irreversible demagnetization. Conventional studies have focused on improving the performance of motors using permanent magnets without heavy rare earth elements. In this study, a robust rotor design process includes the way to restrain irreversible demagnetization using a dysprosium-free permanent magnet. First, the irreversible magnetization of bar-type and V-type magnets, which are basic models of interior permanent magnet synchronous motors, is analyzed. Next, expected demagnetized parts of the main magnets are used as a submagnets, which make magnetic field bypass both sides of the submagnets, and magnets are added in submagnets regions to compensate gap of performance between target model and double type models. Finally, parameter analysis is performed on the design variables of the main magnet. The proposed the robust design process to restrict irreversible demagnetization proves its validity through finite element analysis.

Robust Design Process to Restrain Irreversible Demagnetization of Interior Permanent Magnet Synchronous Motor Applied in Railway Vehicles Using Dysprosium-Free Permanent Magnet

Hyun-Jo Pyo

Papers

Design of 3D-Printed Hybrid Axial-Flux Motor Using 3D-Printed SMC Core

A Study on the Shape of the Rotor to Improve the Performance of the Spoke-Type Permanent Magnet Synchronous Motor

A Study on Core Skew Considering Manufacturability of Double-Layer Spoke-Type PMSM

Eddy Current Loss Reduction in 3D-Printed Axial Flux Motor Using 3D-Printed SMC Core

Robust Design Process to Restrain Irreversible Demagnetization of Interior Permanent Magnet Synchronous Motor Applied in Railway Vehicles Using Dysprosium-Free Permanent Magnet