scholarly journals The Effects of Permanent Magnet Segmentations on Electromagnetic Performance in Ironless Brushless DC Motors

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 621
Author(s):  
Fugang Zhai ◽  
Liu Yang ◽  
Wenqi Fu ◽  
Haisheng Tong ◽  
Tianyu Zhao
Keyword(s):  
Electromagnetic Torque ◽  
Manufacturing Costs ◽  
Brushless Dc Motors ◽  
Brushless Dc ◽  
Dc Motors ◽  
Fem Method ◽  
Dimensional Finite Element ◽  
Process Complexity ◽  
Electromagnetic Performance ◽  
Good Agreement

This paper investigates the electromagnetic torque by considering back electromagnetic force (back-EMF) trapezoidal degrees of ironless brushless DC (BLDC) motors through the two-dimensional finite element method (2-D FEM). First, the change percentages of the electromagnetic torque with back-EMF trapezoidal degrees, relative to those of PMs without segments, are investigated on the premise of the same back-EMF amplitude. It is found that both PM symmetrically and asymmetrically segmented types influence back-EMF trapezoidal degrees. Second, the corresponding electromagnetic torque, relative to that of PMs without segments, is studied in detail. The results show that the electromagnetic torque can be improved or deteriorated depending on whether the back-EMF trapezoidal degree is lower or higher than that of PMs without segments. Additionally, the electromagnetic torque can easily be improved by increasing the number of PMs’ symmetrical segments. In addition, the electromagnetic torque in PMs with asymmetrical segments is always higher than that of PMs without segments. Finally, two ironless PM BLDC motors with PMs symmetrically segmented into three segments and without segments are manufactured and tested. The experimental results show good agreement with those of the 2-D FEM method. This approach provides significant guidelines to electromagnetic torque improvement without much increase in manufacturing costs and process complexity.

scholarly journals Electromagnetic Torque Ripple Reduction In Brushless Dc Motors

2008 ◽  
Vol 13 (1) ◽  
pp. 45-54
Author(s):  
José Roberto B. de A. Monteiro ◽  
Azauri Albano de Oliveira Jr. ◽  
Manoel Luis de Aguiar ◽  
Diógenes Pereira Gonzaga ◽  
Carlos Dias Maciel
Keyword(s):  
Torque Ripple ◽  
Electromagnetic Torque ◽  
Brushless Dc Motors ◽  
Brushless Dc ◽  
Dc Motors ◽  
Torque Ripple Reduction ◽  
Ripple Reduction

Brushless DC Motors with a Three-Section Winding and Two Inductors

2021 ◽  
Vol 1 (1) ◽  
pp. 55-60
Author(s):  
Vladimir M. GRIDIN ◽  
Keyword(s):  
Magnetic Induction ◽  
Power Source ◽  
Air Gap ◽  
The Other ◽  
Electromagnetic Torque ◽  
Bldc Motor ◽  
Brushless Dc Motors ◽  
Brushless Dc ◽  
Power Transistors ◽  
Dc Motors

Two brushless DC motors (BLDC) with a three-section armature windiщ and two cylindrical inductors-magnets are considered. One motor has an ordinary drum-type armature windiщ, and numbers of radial poles in its two inductors differ from each other by a factor of three. The other motor has a toroidal armature winding, and the numbers of radial poles in its two inductors differ from each other by a factor of two. An expression for the distribution of the resulting armature winding magnetic induction over the air gap circumference is given. The optimal relationships between the parameters of two inductors are determined. Expressions are obtained for the ratios of the electromagnetic torques of the considered motors and for the known BLDC motor with a conventional three-section armature winding and a composite inductor consisting of an inner magnetically soft bushing and external poles formed by magnets. The compared machines have the same number of power transistors and are made with the same dimensions of their electromechanical parts, and their armature windings consume the same power from the power source. It has been found that the electromagnetic torque in the considered motor with the ordinary armature winding is approximately a factor of 1.37 greater than in the known motor with a three-section armature winding, whereas in the motor with a toroidal armature winding it is smaller by about a factor of 1.1, i.e., insignificantly. However, the electromagnetic torque pulsation in the motor with a toroidal winding and three power transistors is approximately 3%, whereas in the known motor with three and six power transistors its values are approximately equal to 8 and 4.5%, respectively. The considered motors with simpler cylindrical inductors can compete with the known BLDC motors.

The Research on Suppression Strategies for Electromagnetic Torque Ripples of Brushless DC Motors

2014 ◽  
Vol 910 ◽  
pp. 327-331
Author(s):  
Lian Jun Hu ◽  
Xiao Hui Zeng ◽  
Hong Song ◽  
Xiao Long Huang ◽  
Ming Liu
Keyword(s):  
Control Algorithms ◽  
Electromagnetic Torque ◽  
Tracking Errors ◽  
Brushless Dc Motors ◽  
Brushless Dc ◽  
Dc Motors ◽  
On Line ◽  
Suppression Method ◽  
Torque Ripples ◽  
And Control

Despite of its remarkable active performances, brushless DC motors, which are widely used in mechanical engineering, have an obvious disadvantage in its high electromagnetic torque ripples. In the paper, a ripple suppression method based on predictive controls of stator currents is proposed according to analysis of causes electromagnetic torque ripples generate in commutation periods of brushless DC motors. First of all, a relative accurate prediction is acquired through DC motor on-line parameter corrections based on generalized predictive control algorithms. Then rolling optimizations make tracking errors and control qualities optimized for best control effects. And finally, minimum electromagnetic torque ripples are achieved. The simulation results show that torque ripples can be suppressed effectively with improved reliabilities by using the method proposed.

Recent Challenges and Advances in the Sensorless Commutation of Brushless DC Motors

2020 ◽  
Vol 13 ◽  
Author(s):  
Umesh Kumar Soni ◽  
Ramesh Kumar Tripathi
Keyword(s):  
Initial Position ◽  
Position Estimation ◽  
Current Response ◽  
Flux Linkage ◽  
Brushless Dc Motors ◽  
Position Sensing ◽  
Brushless Dc ◽  
Dc Motors ◽  
Reverse Torque ◽  
Position Detection

Background: Brushless DC motors are highly efficient motors due to its high torque to weight ratio, compact design, high speed operating capability and higher power density. Conventional Hall sensor based rotor position sensing is affected by the heating, vibration, interference and noise. Objective: The innovative, cost effective and easily implementable sensorless techniques are essential in order to achieve high efficiency, reduced current and reduced torque pulsations. Further, a delay free, high load fast startup is also important issue. Methods: In this paper an extensive review of various techniques based on the detection of freewheeling diode current, phase back EMF zero crossoing point detection, back EMF integration method and third harmonic back EMF was done. The study and effect of various PWM strategies on back EMF detection was studied. Later on the sensorless schemes based on flux linkage estimation and flux linkage increment were introduced. The load torque observers, unknown input observers, sliding mode observers, L∞-induced observers, H ∞ - deconvolution filter for back EMF estimation were also reviewed. As the brushless DC motors have no back EMF at starting and for back EMF based commutation a minimum speed is required for sufficient back EMF. Therefore various strategies of open and close-loop reduced current startup have been studied to achieve effective commutation without reverse torque. Initial position detection (IPD) schemes, which are mostly based on saliency and current response to inductance variation, is effective where reverse torque is strictly prohibited. A detailed review of these initial position detection techniques (IPD) has also been presented. Results: The detailed mathematical and graphical analysis has been presented here in order to understand the working of the state-of-art sensorless techniques. Conclusion: The back EMF detection using direct and indirect methods of terminal voltage filtering have the problem of delay and attenuation, PWM noise, freewheeling diode spikes and disturbance in detected back EMFs is a drawback. The parameter detuning, underestimation and overestimation, offset problem, system noise and observer gain variation etc. limit the applicability of observer based technique. Therefore, a more robust and precise position estimation scheme is essential.

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