• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.379-381
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• 1999

This paper presents a study of the performance of a brushless DC motor (BLDCM) speed control system. Recently, most motor controls are implemented in digital electronics. Digital controllers tend to be more accurate, less susceptible to noise and more flexible in terms of programming. The system used a digital PI controller in order to implement the constant speed of Brushless DC motor. Microprocessor used in this experiment is 80c196kc. The applied motor has been constructed using a 50W, 150V, 3000rpm, four-pole motor.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.110-114
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• 2002

Generally, brushless DC motor(BLDCM) driving system uses hall sensors or encoders as the mechanical position or speed sensors. It is necessary to achieve the informations of rotor position for driving trapezoidal type brushless DC motor without any position sensor. This paper proposes a sensorless driving system with rotor absolute position detector circuit which acquires both commutate phase and commutate time by analyzing motor phase voltages. Proposed system is applied to a 10k[W] rating motor which actually used in electrical vehicles of HONDA co.,ltd. The experimental results will show the validity of the proposed system and the practical use of proposed sensorless drive algorithm.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.477-480
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• 2003

Generally, 2 phase excited brushless DC motor(BLDCM) operates only in the region of constant trapezoidal back-EMF on each phase. Therefore the efficiency decreases in comparison with 3phase excited BLDCM. This paper proposes the relation between the usage ratio of voltage and the change of fewer delivery of BLDCM according to extension of conduction intervals.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.3
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• pp.239-246
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• 2003

Brushless D.C. Motor is widely used for industrial application because of high efficiency and high power density. Especially, in home appliance, BLDCM is very useful due to high control performance and low acoustic noise. In this paper, BLDCM and its controller are designed and developed for tread mill application. With the restricted stator structure, permanent magnet rotor is designed for manufacturing and cost effectiveness using CAD and FEM analysis. A ferrite magnetic material is used as a rotor magnet for the cost and temperature advantages. For a stable operation of tread mill, over current and temperature can be detected and protected. The designed BLDCM and its controller was verified by the experimental results.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1569-1576
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• 2014

This paper mainly proposes a direct torque control strategy to minimize torque ripple in brushless DC (BLDC) motor. BLDC motor has large current and torque ripple when one voltage vector applied in one cycle due to its low inductance. Hence, this paper proposed a hysteresis torque control with PWM mode to control the resultant torque. Moreover, when the direct torque control system is operating during the two-phase half-bridge $120^{\circ}$ conduction mode, large torque ripple in commutation area appears every 120 electrical degree. Based on analyzing the root of torque ripple in detail, lookup tables of switching devices states for new half-bridge modulation mode in the positive and negative reference torque put forwarded. Finally, simulations by MATLAB software and experiment results from DSP are presented to verify the feasibility and effectiveness of the proposed strategy operating in four-quadrant operation.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.599-601
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• 2001

This paper investigates the permanent magnet (PM) overhang effect on the characteristics such as cogging torque and torque in brushless DC motor (BLDCM). The overhang effect has been used to enlarge the performance of the radial flux density in BLDCM and balance the force in the axial direction for the reduction of the vibration. 3D equivalent magnetic circuit network method (3D EMCNM) is used for the accurate and efficient analysis. The characteristics of BLDCM are analyzed according to the variation of overhang length and the optimal length and ratio of overhang is determined.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.3
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• pp.246-251
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• 2012

This paper proposes a new position compensation method for misaligned Hall-effect sensors of BLDCM(Brushless DC Motor). If the Hall-effect sensors are installed at wrong position, the exact rotor position cannot be obtained. Therefore, when the BLDCM is controlled with this wrong position, the torque ripple can be increased and the average torque also decreases. The back-EMF of BLDCM can be obtained by using the voltage equation and by multiplying the back-EMF constant and rotor speed. At a constant speed, the estimated back-EMF by using the multiplication of the back-EMF constant and rotor speed is constant, but the estimated back-EMF from the voltage equation decreases at the commutation point because the line-to-line back-EMF of two conducting phases is start to decrease at this point. Therefore, by using the difference between these two estimated back-EMFs, the commutation point of the phase current can be determined and position compensation can be carried out. The proposed position correction method doesn't require additional hardware circuit and can be easily implemented. The validity of the proposed position compensation method is verified through several experiments.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.4
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• pp.336-343
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• 2003

Generally, brushless DC motor(BLDCM) driving system uses hall sensors or encoders as the mechanical position or speed sensors. It is necessary to achieve the information's of rotor position for driving trapezoidal type brushless DC motor without any position sensor. This paper proposes a sensorless driving system with absolute rotor position detecting circuit which acquires both commutating phase and commutating time by analyzing motor phase voltages. Proposed system is applied to a 10k[W] rating motor which actually used in Hybrid Electric Vehicles. The experimental results will show the validity of the proposed system and the practical use of proposed sensorless drive.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.2
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• pp.112-118
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• 2004

Recently, development of rare earth permanent magnet with the high remanence, high coercivity allows the design of brushless motors with very high efficiency over a wide speed range. Cogging torque is produced in a permanent magnet by magnetic attraction between the rotor mounted permanent magnet and the stator teeth. It is an undesired effect that contributes to output ripple, vibration, and noise of machine. This cogging torque can be reduced by variation of magnet arc length, airgap length, magnet thickness, shifting the magnetic pole and varying the radial shoe depth and etc. In this paper, some airgap length and magnet arc that reduce cogging torque are found by finite element method(FEM) and Maxwell stress tensor method. The SPM(Surface Permanent Magnet) type of high-power Brushless DC (BLDC) motor is optimized as a sample model.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.821-823
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• 2002

브러시리스 직류 전동기(Brushless DC Motor : BLDCM)는 기존의 직류 전동기의 단점인 브러시를 제거한 것으로 제어가 간단하면서도 넓은 범위에서 속도 제어가 가능하고 효율이 높으며 저가로 제어기 제작이 가능하다. 그러나 BLDC기을 구동하는데 필수적인 센서는 제품의 가격을 증가시킬 뿐만 아니라 외부 환경-특히 온도의 영향을 많이 받는다는 단점이 있다. 이러한 것은 BLDCM의 사용 환경이 다양해짐에 따라 많은 문제점을 야기하게 되며 따라서 센서리스 구동이 요구된다. 본 논문에서는 BLDCM의 센서리스 구동에서 정상상태 운전뿐만 아니라 안정된 초기 구동에 관한 연구를 수행한다. 정상상태 운전은 측정된 역기전력을 이용하여 회전자의 위치를 결정함으로써 이루어지며, 초기 구동을 개선하기 위해 환류 다이오드로부터 측정된 전류 신호를 이용하여 초기 구동을 하게 된다.