• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.50-52
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• 2001

The BLDC(Brushless DC) motor with the permanent magnet has many merits such as high efficiency and efficiency. These characteristics of the BLDC motor makes them one of the most popular motors in the world today. The C type ferrite magnet is many used in BLDC motor for high performance, especilly low price. Many papers have been written on the analysis of the BLDC motor with C type ferrite magnet. But, most of these target models are contained symmetric distribution of permanent magnet. In this paper, investigations are made on different distribution of permanent magnets for a understanding of the effects of unequal permanent magnet location on the unbalanced cogging torque. Motor torque and cogging torque are obtained by using the 2 dimensional finite element method.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.10
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• pp.652-658
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• 2000

In many cases, ferrite magnets of ferrite bonded magnets used in inner-rotor type small brushless DC(BLDC) motors do not have rotor core. The magnetization directions of permanent magnets do not have only parallel or radial direction. In this case, the characteristics of magnets are different from cored type ones which have uniform magnetization direction. In this paper, the magnetization directions and intensities of a ferrite magnet and a ferrite bonded magnet are analyzed by finite element analysis for magnetization procedure. The characteristics of inner-rotor type BLDC motor are analyzed by using the analyzed results. The validity of the method is verified by comparing the analyzed results with measured ones.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.611-613
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• 2000

Rotor eccentricity exists extensively in BLDC motors because of manufacturing imprecision or bearing defects. In this paper, magnetic fields of a BLDC motor with static rotor eccentricity are analyzed by the time- stepping finite element method. Torque ripple, cogging torque, winding current, counter-em! and unbalanced magnetic force characteristics are obtained. These results are compared with those of a non-eccentric BLDC motor.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.861-863
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• 2000

The rotor of the BLDC motor has permanent magnets on its surface, and is alike the structure of the rotor of synchronous motors. When designing the BLDC motor which has a limited volume in a specific environment, it is important to consider the geometry of the rotor and the length of the airgap. This paper describes a design procedure by analyzing the induced voltage and cogging torque with changing the width of magnets and length of the airgap. And we made a prototype of BLDC motor with this design procedure and our experiment result shows that the cogging torque can be reduced significantly. Also we find a good agreement between the result of experiment and simulation values using Finite Element Analysis.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.25-27
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• 2005

This paper deals with the comparison and analysis of brushless DC (BLDC) motor with radial and polar anisotropic plastic magnet. The open-circuit field distributions and back-emf for BLDC motor with polar plastic magnet are established analytically and the results are validated extensively by comparison with finite element (FE) analyses. On the basis of two dimensional (2-D) analytical solutions, this paper predicts open-circuit field characteristics according to design parameters and makes a comparison between BLDC motor with polar plastic magnet and it with radial plastic magnet in terms of required magnet volume and harmonic of air-gap flux density waveform.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.2
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• pp.114-121
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• 2013

High efficiency operation is required for motors of vehicle to increase fuel efficiency due to the regulation of exhaust gas. This paper presents a control method of fuel pressure to increase fuel efficiency and a sensorless control method of BLDC motor to get higher efficiency than conventional brushed DC motor. Initial rotor position of BLDC motor is detected from current value that is occurred by test voltage pulse and rotor is accelerated by defined sequence to enter sensorless operation mode. The algorithm to control flow rate of fuel pump uses PI controller that is control motor speed to maintain the target fuel pressure commanded by ECU.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1183-1185
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• 2005

This paper describes the optimal design and performance characteristics of the BLDC Motor for Electrical Power Steering System. To develope the optimal dimension within a given volume, BLDC Motor with the low cogging torque is designed and analyzed by FEM analysis. The prototype BLDC Motor has 4 poles rotor and 24 slots stator. To estimate the prototype machine, this paper gives the comparison between the FEM results and the experiment ones.

• Journal of Magnetics
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• v.20 no.1
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• pp.91-96
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• 2015

As many researchers are relentlessly trying to improve the power generation schemes from the power grid, to meet the constantly increasing electricity demand. In this paper, the results of a finite element analysis are carried out to study on a design optimization of an asymmetric air-gap structure in 3-phase Permanent Magnet Brushless DC Motors. To achieve a high efficiency for a 3-phase PM BLDC motor, the asymmetric air-gap structure is proposed considering the rotation direction of a motor. Generally, a single-phase BLDC motor is applied asymmetric air-gap structure for starting. This is because the asymmetric air-gap structure causes reluctance variation so the motor can utilize reluctance torque toward a rotation direction. In this paper, the asymmetric air-gap is applied to 3-phase BLDC SPM motor so it utilizes reluctance torque with alignment torque. A proposed model is designed by 2-D FE analysis and the results are verified by experimental test.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.686-689
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• 2014

This Paper is about the study that use the IPM(Intelligent Power Module) which is a integrated switching module to drive inverter gates for driving of a multi-pole BLDC(Brushless Direct Current) motors. When designing a inverter using the various manufacturers IPM, it suggests a electronic circuit system to evaluate the electrical and logical characteristics of the IPM with various brands.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.1
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• pp.9-18
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• 2007

This paper proposes the modeling of sensorless drive system using 120 degree conduction method for IPM (Interior Permanent Magnet) BLDC motors and analyzes characteristics of the terminal voltage that is used to detect the rotor position. This paper shows that the ZCP (Zero-Crossing Point) of the measured terminal voltage used In sensorless control is ahead of that of the back EMF of IPM motors because they have a saliency. This research also analyzes that the amount of position detection error is related to saliency, rotor speed, and load condition. In addition, this paper shows that motors have bigger advance angles than we have expected because the ZCP of terminal voltage precedes the actual ZCP, and under operation conditions such as heavy load and high speed it may generate abnormal currents that flow toward opposite direction after phase current becomes zero.