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Sinusoidally-fed permanent magnet brushless dc (PM BLDC) motors are supposed to develop effectively ripple-free dynamic torques. This is done by having a sinusoidal flux density distribution in the airgap followed by a rotor position dependent sinusoidal excitation of the phase windings. There are different rotor topologies used in these motors. In this paper, five types of generally used rotor topologies...
This paper presents the design and analysis of a novel machine family-Enclosed Rotor Radial flux Halbach array Permanent Magnet Brushless DC motor (PMBLDC) for spacecraft applications. Initial design, selection of major parameters and air gap magnetic flux density are estimated using the analytical model of the machine. The proportion of the halbach array in the machine was optimized using FE to obtain...
In this paper, we propose an analytical method of polar anisotropic ferrite bonded magnet to outer rotor type brushless dc motor considering magnetizing process. The characteristics of polar anisotropic magnets are different from cored type ones which have uniform magnetization direction. Consequently, the magnetization directions of ferrite bonded magnet are analyzed by finite element analysis for...
This paper presents a new initial rotor position estimation method for brushless dc motors (BLDC). It consists in injection of four short voltage pulses at the motor terminals and then based on the evaluation of the voltage measured at the terminal of the non-energized (floating) stator phase, the position is estimated. The first three pulses are applied for a very short time to evaluate the rotor...
The air-gap field in slotless permanent magnet motor is small. Based on the surface mounted permanent magnet, this paper compares the parallel magnetization with the radial magnetization by finite element calculation. The results show that parallel magnetization can provide larger air flux in the slotless motor. The large effective air gap makes the end leakage serious. In order to resolve this problem,...
Considering the characters of high permeability, high resistivity, low loss and low cost for soft magnetic ferrite in high-frequency alternating magnetic field, this paper proposes a novel high speed permanent-magnet motor based on soft magnetic ferrite. Soft magnetic ferrite ring is used for stator core, rare earth permanent magnet ring serves as the rotor poles, and the slotless configuration with...
Based on the characteristics of transverse flux permanent magnet machine (TFPM), a novel multi-pole and multi-phase TFPM topology with assembled stator and concentrated flux rotor is presented in this paper. The associated electromagnetic fields of the prototype are investigated by means of three dimension equivalent magnetic network method (3DEMNM). It is shown the unique multi-phase structure of...
In 1991, recorded production of bonded rare-earth magnets was 32 times as high as in 1981. To determine the reason for this rapid growth, an industrial and technical review of the last decade is made. The results show that the growth can be attributed to three major factors: the appearance of a large new market in the 1980's, development of novel materials with high performance, and successive efforts...
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