• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.641-645
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• 2008

In this paper, vibration sources of the BLOC motor are identified and the motor vibrations are reduced by structural modification. For vibration characteristic identification, vibration signals measured by an accelerometer when the BLOC motor is moving. These signals are presented in a waterfall plot in order to find the dependency of frequency components on the motor speed. It is found that main vibration source is BLOC motor test rig. From finite element analyses and some experiments, it is also found that resonances occur because the natural frequencies of the test rig exist in usual driving speed rang. To shift the natural frequencies outside the driving rang, the test rig is modified increase stiffness. It is verified that considerable amount of vibration are reduced by the structural modification.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.802-804
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• 2002

An analysis of the skeleton type BLDC motor is presented. The single phase skeleton type BLDC motor consists of the stator, rotor with the permanent magnet, and drive circuit with hall sensors that detect the rotor position. The major factors for the initial starting, efficiency, and torque ripples of the skeleton type BLDC motor are the detent groove of the stator and the lead angle of the phase voltage. The performance characteristics according to the angle and height of the detent groove is analyzed. The optimum lead angles of the phase voltage with the torque ripple and motor efficiency is described using the finite element method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.1
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• pp.38-46
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• 2000

This study have established proper mathematical equivalent model of Brushless DC (BLDC) motor and estimated the motor parameter by means of the back-emf measurement as being the step input to the controlled target BLDC motor. And the validity of proposed estimation method is confirmed by the test result of step response. As well, we have designed the reasonable digital controller as a consequence of the root locus method which is obtained from the open-loop transfer function of BLDC motor with hall sensor, and the determination of control gain for variable speed control. Here, revised Ziegler-Nichols tuning method is applied for the proper digital gain establishment, and the system stability is verified by the frequency domain analysis with Bode-plot and experimentation.

• 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.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.3
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• pp.40-46
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• 2009

Toroidally-wound brushless direct-current (BLOC) machines are compact, highly efficient, and can work across a large magnetic gap. For these reasons, they have been used in pumps, flywheel energy storage systems and left ventricular assist devices among others. The common feature of these systems is a spinning rotor supported by a set of (either mechanical or magnetic) bearings. From the view point of dynamics, it is desirable to increase the first critical speed of the rotor so that it can run at a higher operating speed. The first critical speed of the rotor is determined by the radial stiffnesses of the bearings and the rotor mass. The motor also affects the first critical speed if the rotor is displaced from the rotating center. In this paper, we analytically derive the flux density distribution in a toroidally-wound BLOC machine and also derive the negative stiffness of the motor, based on the assumption that the rotor displacement perturbs the flux density distribution linearly. The estimated negative stiffness is validated by finite element analyses.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1231-1235
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• 2007

This paper presents the dynamic characteristics of a linear brushless dc (BLDC) motor with permanent magnet excitation for the precision conveyor according to the load condition. Dynamic performance of the linear BLDC motor driven with 6 step inverter such as thrust force and speed is simulated by finite element method coupling with external circuit and measured for the prototype motor. The results of finite element analysis are compared to the experimental results and verify reliability.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.1
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• pp.1-8
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• 2006

Now a day, owing to high efficiency and easy speed control of brushless DC(BLDC) motor, the demand of BLDC motor that has high power and low noises are increasing. Especially demand of interior permanent magnet(IPM) BLOC with high efficiency and high power in electric motion vehicle is increasing. IPM BLDC motor has permanent magnets in the rotor. Because it has two different flux paths, magnetic reluctance differences are generated in d-axis and q-axis. As the result of the inductance differences that are generated by the saliency(magnetic reluctance differences) in the rotor, the motor has structure advantage that has the additional reluctance torque except a magnet torque and because magnet is situated inside the rotor, the mechanical structure is strong. Therefore IPM BLDC motor makes possible to have high speed and high power. This paper presents a design and characteristics analysis of IPM BLDC motor for electric vehicle. To design IPM BLDC motor, surface mounted permanent magnet(SPM) BLDC motor is used as the initial design model. According to the shape-ratio() of permanent magnet, the characteristic of IPM BLDC motor is analyzed by Finite element method (FEM). Characteristics analysis results of the designed motor are compared with the experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.1930-1936
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• 2007

According to previously published paper the phase advance angle is adopted to the BLDC motor drive with high speed. The report proposed describes the optimum algorism that phase current is in phase with the initial flat region of back EMF. This report studies the need of more leading phase advance angle compared with in phase concept between phase current and back EMF. In case of high reactance this report proposes the more phase advance angle than in phase. The test results more rms value of phase current and output power due to more phase advance angle than in phase. It will be helped the high power operation of BLDC motor at high speed.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.655-657
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• 1995

Variable Structure Controller is well known to be a robust controller. Recently, Evolution Strategy is used as a effective search algorithm. In this paper, we propose a Variable Structure Controller combined with Evolution Strategy. Evolution Strategy is used to estimate the unknown parameters, the control gain and the thickness of saturation function boundary layer of Variable Structure Controller. From the experiment, we found the proposed Variable Structure Controller shows accurate tracking ability and robust performance in the BLOC motor position control system.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.6
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• pp.589-595
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• 2007

This paper presents a new method on controller design of brushless dc motors. In such drives the current ripples are generated by motor inductance in stator windings and the back EMF. To suppress the current ripples the current controller is generally used. To minimize the size and the cost of the drives it is desirable to control motors without the current controller and the current sensing circuits. To estimate the motor CUlTent it is modeled by a neural network that is contigured as an output-error dynamic system. The identified model is essentially a one step ahead prediction structure in which past inputs and outputs are used to calculate the current output. Using the model, a state feedback controller to compensate the effects of disturbance has been designed. The controller is implemented by a 16-bit microprocessor and the effectiveness of the proposed control method is verified through experiments.