• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.9
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• pp.437-442
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• 2006

Cogging torque, the primary ripple component in the torque generated by permanent magnet (PM) motors, is due to the slotting on the stator or rotor. This article shows the reduction of cogging torque in a novel axial flux permanent magnet (AFPM) motor through the various design schemes. 3D finite element method is used for the exact magnetic field analysis. The effects of slot shapes and skewing of slot on the cogging torque and the average torque have been investigated in detail.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.161-161
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• 2010

In order to achieve low power consumption and the uniform power spectrum of LED BLU (Back Light Unit) system, new circuits with a 2 stage L-C (Inductor-Capacitor) coupler have been proposed. From the simulation results based on our proposed model, the ripple power of the L-C regulation-embedded BLU circuit shows a dramatic reduction by more than 89.3% as compared to the normal BLU (without L-C circuits). This indicates that the proposed circuit is very promising for the realization of high-efficiency BLU circuits.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.8
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• pp.363-368
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• 2006

This paper presents a new method on reducing commutation torque ripples generated in brushless dc motor drives. In such drives the current ripples are generated by motor inductance in stator windings and the back EMF. The ripples suppression techniques that are practically effective in high speed as well as in low speed regions are rarely found. The proposed method here is based on a strategy that the commutation intervals of the incoming ang the outgoing phases can be equalized by a proper PWM control. The controller is implemented by a 16-bit microprocessor and effectiveness of the proposed control method is verified through experiments.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.669-670
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• 2006

This paper deals with the optimum rotor design solution on torque ripple reduction for a SynRM with concentrated winding using response surface methodology (RSM). The RSM has been achieved to use the experimental design method in combination with finite element method (FEM)and well adapted to make analytical model for a complex problem considering a lot of interaction of design variables. Comparisons are given with characteristics of a SynRM according to flux barrier number, flux barrier width variation, respectively.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2182-2191
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• 2016

This study proposes a novel frame anti-vibration controller for position sensorless PMSM drive application. This controller is called specific component reduction controller (SCRC). SCRC can function without an accelerometer and can achieve speed variable control. This study mainly comprises the following phases. First, the position sensorless control method will be provided. Second, the frame vibration model and load torque ripple will be shown. Third, SCRC will be discussed and its stability will be analyzed. Finally, experimental results show that SCRC can achieve speed variable anti-vibration control and compensate target frequency torque ripple.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1120-1122
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• 2000

Switched Reluctance Motors(SRM) attract much attention in motor because they are reliable and inexpensive. With advance in power electronics and high-speed processors, the performance of SRM has been enhanced greatly But because of its geometric and magnetic structure, the switched reluctance motor naturally creates torque ripples during the commutations of the currents from a supplied phase to an other one. This paper presents the torque ripple reduction using hysteresis current control among of current control techniques.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.5
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• pp.371-378
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• 2015

In this paper, a different type of pulse width modulation (PWM) control scheme for a buck converter is introduced. The proposed buck converter uses PWM with frequency hopping and a low quiescent.current low dropout (LDO) voltage regulator with a power supply rejection ratio enhancer to reduce high spurs, harmonics and output voltage ripples. The low quiescent.current LDO voltage regulator is not described in this paper. A three-bit binary-to-thermometer decoder scheme and voltage ripple controller (VRC) is implemented to achieve low voltage ripple less than 3mV to increase the efficiency of the buck converter. An internal clock that is synchronized to the internal switching frequency is used to set the hopping rate. A center frequency of 2.5MHz was chosen because of the bluetooth low energy (BLE) application. This proposed DC-DC buck converter is available for low-current noise-sensitive loads such as BLE and radio frequency loads in portable communications devices. Thus, a high-efficiency and low-voltage ripple is required. This results in a less than 2% drop in the regulator's efficiency, and a less than 3mV voltage ripple, with -26 dBm peak spur reduction operating in the buck converter.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.5
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• pp.1187-1195
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• 2013

Photovoltaic inverters should always track the maximum power of solar cell arrays in operation. Also, they should be irrespective of the maximum power point voltage of a wide range of solar cells in tracking the maximum power point. If the current ripple of solar cells occurs, the function of maximum power point tracking drops, and normal tracking is difficult when solar radiation or the maximum power point changes. To solve this problem, this paper proposed a new maximum power point tracking algorithm with high efficiency and an algorithm to reduce the current ripple of solar cells. According to the results from the test on 4KW grid-connected PV inverter, the efficiency of maximum power point tracking and inverter output and the total harmonic distortion of inverter output current showed 99.97%, 97.5% and 1.05% respectively. So, the inverter showed excellent performance, and made possible stable maximum power point tracking operation when the solar radiation rapidly changed from 100% to 10% and from 10% to 100% for 0.5 seconds.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.3
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• pp.122-128
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• 2012

An interleaved boost converter has many advantages such as current ripple reduction, switching effective double, etc. Due to these advantages, the interleaved boost converter applies to the power factor correction circuit. However, there are almost no analysis results because the input voltage and current are time-varying system in the power factor correction application. Therefore, in this paper, the current ripples of the power factor correction circuit using single-phase boost dc-dc converter and 2-phase interleaved boost dc-dc converter are compared and analyzed in detail. In order to verify the validity, computer simulation and experimental are performed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.11
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• pp.1541-1543
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• 2013

This paper presents a spherical motor which can control in multi-degree of freedom operation. The spherical motor has been researched by many types of structure. Thhis paper shows a spherical shaped airgap and surfaced permanent magnets. Especially, The motor consists of dual rotor cores. Unlike a cylindrical motor, the spherical motor design can be considered with azimuth direction on spherical coordinates. Therefore the permanent magnet surfaced on the rotor need to be designed optimally in order to generate a sinusoidal magnetic flux density in the airgap. This paper presents results of optimal design for reducing torque ripple of the multi-degree of freedom spherical motor.