Rotor Permanent Magnet Brushless DC Research Articles

Radial basis function‐based Pareto optimization of an outer rotor brushless DC motor

AbstractThis paper presents the development of an optimization and modeling method for the objective functions of output power, efficiency and weight of an outer rotor permanent magnet brushless DC (BLDC) motor based on radial basis function (RBF) approximation technique. The proposed RBF‐based Pareto optimization method requires less knowledge about electric/magnetic formulas and can replace conventional optimizations based on these equations with higher accuracy. To apply the proposed optimization method, the initial design should be developed using such equations. Therefore, RBFs are used to model and predict engine behavior. To optimize the objective functions, we used a genetic algorithm optimization technique with nonlinear electric and magnetic constraints to find the Pareto front set. The design obtained by the proposed radial basis function Pareto optimization (RBFPO) method was finally verified by Ansoft Maxwell. The results of optimal design using the RBFPO method have higher output power and efficiency. Also, in addition to the advantage of a favorable accuracy, RBF‐based models are significantly faster than models available in simulation tools.

Efficiency Improvement of Permanent Magnet BLDC With Halbach Magnet Array for Drone

In this paper, the outer rotor permanent magnet brushless DC motor (BLDC) with halbach magnet array was studied to improve the power characteristics of BLDC for drones. First, the BLDC motor applied to the currently commercial drone was selected as the target model and improved design was carried out. Spec generation was carried out for target BLDC model and the base model was designed and manufactured. Based on the base model, am improved design was applied using the halbach mag-net array using Response Surface Method (RSM). Applying the halbach magnet array can reduce the leakage flux and improve the efficiency by reducing the iron loss of the motor. In addition, the design for reducing the weight of the motor was carried out using RSM. It was confirmed by Finite Element Analysis (FEA) that the power characteristics of the designed improved model improved compared to the target BLDC model.

Effects of static eccentricity on the no‐load back electromotive force of external rotor permanent magnet brushless DC motor used as in‐wheel motor

The no-load radial magnetic field and no-load back electromotive force (EMF) of external rotor permanent magnet brushless DC motor (PMBLDCM) are calculated by applying the correction coefficient of magnetic conductance here, taking into account the stator slotting and static eccentricity effects. An external rotor PMBLDCM with 51-slot/46-pole, used as in-wheel motor, is taken as an example, the analytical calculation results of the no-load back EMF are validated by the finite-element method and experiment. The influences of static eccentricity ratio on the no-load radial magnetic field and no-load back EMF are investigated based on the analytical model. The investigation shows that static eccentricity does not change the harmonic contents of no-load radial magnetic field, so it does not change the harmonic contents of three-phase no-load back EMFs. However, static eccentricity changes the space order of no-load radial magnetic field, resulting in the different total harmonic distortions of three-phase no-load back EMFs; in other words, the asymmetric distortions of three-phase no-load back EMFs are generated. The asymmetric distortions of three-phase no-load back EMFs are intensified with the increase in static eccentricity ratio.

Analytical model for armature reaction of outer rotor brushless permanent magnet DC motor

This study presents an analytical model for calculating the armature reaction magnetic field of outer rotor permanent magnet brushless DC motor (PMBLDCM) in stator stationary coordinate system (SSCS) and rotor rotation coordinate system (RRCS). Firstly, an expression of armature reaction magnetic field of single-phase winding is deduced, without considering slotting effect. Afterwards, analytical expressions of armature reaction magnetic field in both SSCS and RRCS regardless of slotting effect are obtained using vector addition method. Then complex relative permeances of outer rotor BLPMDCM in SSCS and RRCS are analysed, respectively. Finally, analytical solutions of the armature reaction magnetic field in both SSCS and RRCS are derived, respectively, by multiplying the slotless armature reaction magnetic field and the complex relative magnetic permeance, the self- and mutual inductance are calculated by the armature reaction magnetic field. A 46-ploes-51-slots outer rotor BLPMDCM is set as an example, the accuracy of proposed analytical model is verified by the Finite Element Method. Based on this analytical model, the pattern of slotting effect on armature reaction of both outer rotor and internal stator are analysed, respectively, as well as spatial order characteristics and frequency characteristics of armature reaction for outer rotor PMBLDCM in SSCS and in RRCS.

Exterior Rotor Permanent Magnet Brushless Dc Motor through Numerical Method of the Electromagnetic for Torque Improvement

In this paper, Numerical method based Exterior Rotor Permanent Magnet Brushless Direct Current (ERPMBLDC) is proposed aiming to integrate its torque. The ERPMBLDC Machine construction and principle of operation will be designed using Finite Element Method Magnetic 4.2(FEMM4.2) software. Then the flux pattern distribution based on the numerical method of ERPMBLDC motor estimation derived. The proposed motor parameters such as flux pattern, phase angles for maximum torque and torque were analyzed and compared by simulation and by experimental results.

Numerical and Experimental Investigation of Heat Flow in Permanent Magnet Brushless DC Hub Motor

This paper investigates the heat dissipation in the hub motor of an electric two-wheeler using lumped parameter (LP), finite element (FE) and computational fluid dynamic (CFD) models. The motor uses external rotor permanent magnet brushless DC topology and nearly all of its losses are generated in the stator. The hub motor construction restricts the available conductive paths for heat dissipation from the stator to the ambient only through the shaft. In contrast to an internal rotor structure, where the stator winding losses are diffused via conduction, here convection plays a major role in loss dissipation. Therefore, a LP thermal model with improved convection modelling has been proposed to calculate the temperature of the components inside the hub motor. The developed model is validated with the FE thermal model and the test data. In addition, CFD tools has been used to accurately model the internal and the external flow as well as the convective heat transfer of the hub motor. Finally, an optimization study of the hub motor has been carried out using the CFD model to improve heat transfer from the stator.

Optimization of the permanent magnet brushless DC motor employing finite element method

PurposeThe purpose of this paper is to elaborate the algorithm and computer code for the structure optimization of the outer rotor permanent magnet brushless DC motor and to execute optimization of selected motor structure using the non‐deterministic procedure.Design/methodology/approachThe mathematical model of the device includes the electromagnetic field equations with the nonlinearity of the magnetic core taken into account. The numerical implementation is based on the finite element method and stepping procedure. The genetic algorithm has been applied for the optimization. The computer code has been elaborated.FindingsThe elaborated computer software has been applied for the optimization and design of BLDC motors. The elaborated algorithm has been tested and a good convergence has been attained.Originality/valueThe presented approach and computer software can be successfully applied to the design and optimization of different structure of BLDC motors.

Simulation of Outer Rotor Permanent Magnet Brushless DC Motor Using Finite Element Method for Torque Improvement

A method of simulation and modeling outer rotor permanent magnet brushless DC (ORPMBLDC) motor under dynamic conditions using finite element method by FEMM 4.2 software package is presented. In the proposed simulation, the torque developed at various positions of the rotor, under a complete cycle of excitation of the stator, is analysed. A novel method of sinusoidal excitation is proposed to enhance the overall torque development of ORPMBLDC motor.

Field‐circuit simulation of the dynamics of the outer rotor permanent magnet brushless DC motor

PurposeThe purpose of this paper is to elaborate a mathematical model of dynamic operation of the permanent magnet brushless DC (BLDC) motor with outer rotor and investigate the influence of magnets width on the dynamic parameters.Design/methodology/approachThe mathematical model of the devices includes: the equation of the electromagnetic field, the electric circuit equations and equation of mechanical motion. In elaborated algorithm, all these equations are coupled – therefore they are solved simultaneously. The numerical implementation is based on finite element method and step‐by‐step algorithm. The non‐linear‐coupled field‐circuit equations have been solved by using the Newton‐Raphson algorithm. The computer code for dynamics simulation of the machine has been developed.FindingsThe elaborated algorithm and the computer code have been applied for the 2D simulation of BLDC motor dynamics. The algorithm has a good convergence and its usefulness was proved. Various results of the analysis are presented and discussed.Originality/valueThe presented approach and computer code can be successfully applied to the design and optimization of different structure of the BLDC motors.