• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.754-756
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• 1987

In this paper, a new Harmonic Torque Factor(HTF) that represents torque ripple of induction motor is proposed. Trapezoidal PWM is analyzed to torque ripple by HTF and than we obtain optimum triangular factor at some carrier ratio. Six-step, sinusoidal PWM and Trapezoidal PWM are compared and evaluated for choosing a good control strategy of PWM inverter. It turns out that six-step inverter is better than sinusoidal PWM and Trapezoidal PWM when their carrier ratio is 9, and Trapezoidal PWM is superior to sinusoidal PWM. At induction motor is driven by PWM inverter, torque ripples are investigated by computer simulation using d-q two axis model. It is proved that a new Harmonic Torque Factor ix valid.

• Journal of Power Electronics
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• v.16 no.1
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• pp.268-276
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• 2016

A hybrid sinusoidal-pulse current (HSPC) charging method for the Li-ion batteries in electric vehicle applications is proposed in this paper. The HSPC charging method is based on the Li-ion battery ac-impedance spectrum analysis, while taking into account the high power requirement and system integration. The proposed HSPC method overcomes the power limitation in the sinusoidal ripple current (SRC) charging method. The charger shares the power devices in the motor inverter for hardware cost saving. Phase shifting in multiple pulse currents is employed to generate a high frequency multilevel charging current. Simulation and experimental results show that the proposed HSPC method improves the charger efficiency related to the hardware and the battery energy transfer efficiency.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.142-145
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• 2001

In this paper the electromagnetic torque developed in IPMSM(Interior Permanent Magnet Synchronous Motor) is analyzed. If flux distributions in the motor are not sinusoidal, a sinusoidal current produces important torque ripple. Torque ripple causes vibration and noise of motors. The optimized current waveforms for ripple free is able to be obtained by analysis of Back-EMF and torque equation. The method to find the optimal current is based on numerical predetermination. In this paper proposes current waveform which can eliminate the torque ripple, and the validity is verified through the simulation.

• Journal of Power Electronics
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• v.6 no.2
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• pp.139-145
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• 2006

This paper describes the ultra precise position estimation of a servomotor using a sinusoidal encoder based on Arcsine Interpolation Method for the cost reduction of circuit design. The amplitude and offset errors of the sinusoidal encoder output signals, from the encoder itself and analog signal processing procedures, are effectively compensated and on-line tuned by utilizing a low cost programmable differential amplifier without any special expensive equipment. For a theoretical evaluation of the practical resolution of this system, the relationship between the amplitude of ADC(Analog to Digital Converter) input signal errors and the anticipated resolution is also addressed. The performance of the proposed method is verified by comparing it with speed control characteristics of the servomotor driving system using a digital incremental 50,000ppr encoder in the experiments.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.6
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• pp.52-63
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• 1995

This paper presents a detailed derivation of the equations of motion for the stable member of a four-axis platform. Gimbal bearing friction is considered for motion analysis. First, dynamic characteristics of platform, gimbal and gyro with Coulomb friction are studied due to vehicle's angular motion. Second, Vehicle's motion is assumed the sinusoidal function and dynamic characteristics of platform, gimbal and gyro are studied. Conclusively, considering effects of Coulomb friction, they could not follow the vehicle's angular motion and have constant errors. In case of sinusoidal motion, relative angles for each gimbal are amplified, but they are sinusoidal function with almost the same phases.

• Journal of the Korean Society of Hazard Mitigation
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• v.6 no.1 s.20
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• pp.39-48
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• 2006

A laboratory investigation was performed to estimate the moduli values of asphalt concrete mixture due to various sinusoidal loadings in compression and tension. Total five modes of loading were used under five testing temperatures of 32, 50, 68, 86, and $104^{\circ}F$ (0, 10, 20, 30, and $40^{\circ}C$); repeated compressive haversine loading with rest period, repeated tensile haversine loading with rest period, cyclic compressive loading, cyclic tensile loading, and alternate tensile-compressive loadings. The test results showed that, due to the repeated haversine loading with rest period, asphalt concrete demonstrated similar moduli in tension and compression at low temperatures,(0 and $10^{\circ}C$) while those moduli were different at high temperatures (20, 30, and $40^{\circ}C$). At high temperatures the compressive moduli were always higher than the tensile moduli. The uniaxial tensile moduli were higher than indirect tensile moduli at low temperatures. However, those moduli were similar at high temperatures. In uniaxial cyclic tension, compression, and alternate tension-compression tests, compressive moduli were higher than tensile and alternate tensile-compressive moduli throughout the temperatures. Generally, the moduli from the repeated haversine loading with rest period were always lower than those from the cyclic sinusoidal loading. The difference in moduli from the repeated haversine loading with rest period and cyclic sinusoidal loading becomes more significant as the temperature decreases.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.123-126
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• 2000

STC(Sinusoidal Transform Coding) 방식은 음성신호의 주파수 영역에서 스펙트럼 피크치들을 정현파로 모델링하여 합성하는 방식을 말한다. 저전송률 STC 방식에서는 전송되는 정보량을 줄이기 위해 스펙트럼 피크를 대신해 음성신호의 스펙트럼 포락선 정보와, 피치정보를 이용하여 얻어지는 고조파 성분들을 정현파로 모델링하여 음성을 합성한다. 본 논문에서는 음성신호의 정현파 모델에 기반하여 2.4kbps 전송속도를 갖는 음성부호화 알고리즘을 제안하였으며, 실험결과로 합성음의 파형과 스펙트럼 특성, 위상특성, 그리고 MOS(Mean Opinion Score) 테스트를 이용한 합성음의 음질을 비교/분석 하였다.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.179-183
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• 2001

This paper presents a simple current control strategy for matrix converters based on the extension of PWM method for inverters. A novel and efficient PWM algorithm is developed. The algorithm is verified through simulation and experiments employing a 2-kVA prototype. The results of simulation and experiment prove the instantaneous control capability of the output current with the sinusoidal input current.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.95-97
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• 2006

Cogging torque is often a principal source of vibration, noise and difficulty of control in BLDC motors. Therefore, this paper will present a design method of magnetization system with sinusoidal air-gap flux density distribution of Nd-Fe-B magnets in ring type for reduction of Vibration and Noise and low manufacturing cost.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.2
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• pp.23-27
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• 2008