• Journal of Power Electronics
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• v.19 no.1
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• pp.134-145
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• 2019

A single-phase step-up five-level inverter topology with a new phase-shifted pulse width modulation (PS-PWM) strategy is proposed in this paper. When compared with conventional single-phase five-level inverter topologies, the proposed topology can realize multilevel inversion with a double step-up ratio, a reduced number of switching devices and self-balanced capacitor voltages. When compared with the conventional PS-PWM strategy, the new PS-PWM strategy can be implemented with one carrier reduced, which makes it much easier to implement in a digital signal processor (DSP) system. Experimental results have been presented to verify the effectiveness of the proposed inverter and the PS-PWM strategy.

• The Journal of the Acoustical Society of Korea
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• v.16 no.4
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• pp.11-20
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• 1997

The passive noise control techniques used until now cancel the noise in terms of the characteristics of materials, which increase the mass and the dimension and have a limit that is effective only to attenuate the high frequency components of the noise. But the active noise control techniques developed in recent years have merits that they decrease the mass and the dimension and are effective to attenuating the low frequency noises. In this paper, the real-time active noise control system attenuating the engine booming noise in a car using the digital signal processing(DSP) techniques in terms of the principle of active noise control. The multiple-error filtered-x LMS(Least-Mean Square) algorithm is used as the adaptive algorithm for active noise control and is implemented using the DSP processor Motorola DSP56001 as a controller. According to the result that the experiments are performed for the engine as the RPM changes in a car, the noise attenuating performances are achieved in an overall car interior and is verified to be 20 dB higher for pure-tone and globally, 15 dB.

• The Journal of the Acoustical Society of Korea
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• v.35 no.3
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• pp.216-222
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• 2016

Generation of a quiet zone in noisy environment is undoubtedly of considerable realistic significance. This paper describes development and implementation of a multichannel real-time active noise control (ANC) system for 3 dimensional noisy environment to enhance the quiet zone performance in terms of size and noise cancellation gain. The proposed ANC system employes a multichannel delay-compensated filtered-X least mean square (FXLMS) algorithm; its real-time implementation is designed in TMS320C6713 digital signal processor (DSP) board. The system is evaluated for cancelling various tonal frequency noises in the range from 100 to 500 Hz, and the performance is then illustrated by measuring the quiet zone in terms of sound pressure level (SPL) attenuation. Experiment results show that a quiet zone of quiet with satisfactory size and maximum 24 dB noise attenuation is successfully generated.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.987-990
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• 2003

산업현장에서의 인터넷환경 및 원격 제어를 위한 시스템 개발에서 신뢰성이 있고 경제적이며 지능적인 Power Supply가 요구되고 있다. 최근 통신시스템의 Power Supply는 수 kA이상의 출력전류를 가지고 있으며 최소 10개 이상의 모듈로 이루어져 있다. High-End 서버 시스템과 같이 수백 개의 마이크로프로세서를 내장한 시스템은 수십 kW의 전력을 소모한다. 이들이 사용하는 Power Supply는 별도의 시스템 제어기와의 통신으로 시스템에서 발생하는 발열, 소모전력, Total Harmonic Distortion (THD)에 대한 정보를 바탕으로 시스템이 갖는 각각의 Module에 대해 효과적이고 신뢰성 있는 전력공급을 하여야 만다. Distributed Power System (DPS)에서 가장 중요만 역할을 담당하는 Power Factor Correction (PFC) AC-DC Converter의 디지털 제어는 시스템 제어기와의 통신능력을 충분히 고려하면서 DPS를 위한 적합한 솔루션을 제공할 것이다. 본 논문에서는 Digital Signal Processor (DSP)를 사용하여 PFC 제어에 필요한 전파정류전압, 입력전류, 출력전압을 계측하여 역률개선과 THD의 저감을 위한 전류의 추종을 제어하면서 이들 제어기에서의 파라미터를 PC를 통해 모니터하여 최근의 추세를 만족시킬 수 있는 시스템을 구현할 수 있을 것으로 사료된다.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.1
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• pp.26-34
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• 1999

According to increase of nonlinear power electronics equipment, active power filters have been researched and developed for many years to compensate harmonic disturbances and reactive power. However the commercial of active power filter is being proceeded slowly, because the cost of active power filter compared to the passive filter for harmonic and reactive power compensation is expensive. Especially, the use of DSP (Digital Signal Processing) chip, which is frequently used to control 3-phase active power filter, is a factor of increasing the cost of active power filters. On the other hand, the use of only analog controller makes the controller's circuits much more complicate and depreciates the flexibilities of controller. In this paper, a controller with low cost for 5[kVA] 3-phase active power filter system is designed. To reduce the expense of active filter system, the presented controller is composed of digital control part using Intel 80C196KC $\mu$P and analog control part using hysteresis controller for current control. Characteristic analysis of designed controller for active filter system is performed by computer simulation and compensating characteristics of the designed controller are verified by experiment.tegy can apply to the vector control, leading to better output torque capability in the ac motor drive system. This strategy is that in the overmodulation range, the d-axis output current is given a priority to regulate the flux well, instead the q-axis output curent is sacrificed. Therefore, the vector control even in the overmodulation PWM operation can be achieved well. For this purpose, the d-axis output voltage of a current controller to control the flux is conserved. the q-axis output voltage to control the torque is controlled to place the reference voltage vector on the hexagon boundary in case of the overmodulation. The validity of the proposed overall scheme is confirmed by simulation and experiments for a 22[kW] induction motor drive system.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.1
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• pp.51-58
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• 2013

As it is changing into aging society, rehabilitation, welfare and sports industry markets are being expanded fast. Especially, the field of vital signals interface to control welfare instruments like wheelchair, rehabilitation ones like an artificial arm and leg and general electronic ones is a new technology field in the future. Also, this technology can help not only the handicapped, the old and the weak and the rehabilitation patients but also the general public in various application field. The commercial bio-signal measurement instruments and interface systems are complicated, expensive and large-scaled. So, there are a lot of limitations for using in real life with ease. this thesis proposes a wireless transmission interface system that uses EMG(electromyogram) signals and a control module to manipulate hardware systems with portable size. We have designed a hardware module that receives the EMG signals occurring at the time of wrist movement and eliminated noises with filter and amplified the signals effectively. DSP(Digital Signal Processor) chip of TMS320F2808 which was supplied from TI company was used for converting into digital signals from measured EMG signals and digital filtering. We also have used PCA(Principal Component Analysis) technique and classified into four motions which have right, left, up and down direction. This data was transmitted by wireless module in order to display at PC monitor. As a result, the developed system obtains recognition success ratio above 85% for four different motions. If the recognition ratio will be increased with more experiments. this implemented system using EMG wrist direction signals could be used to control various hardware systems.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.479-483
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• 1997

In general, motor parameters can be divided into mechanical/electrical parameters and harmonic parameters. Mechanical/electrical parameters identification of motor have been studying systematically for a long time. But, systematical study on harmonic parameters analysis for efficient motor drive system are very poor. The goal of this paper is to propose analyzing method of harmonic parameters for motor drive system with various experimental graphic screens and numerical results and to develope harmonic parameters analyzer. A developed analyzer is made up 586-PC and DSP (digital signal processor) board, motor drive system, power and harmonic parameters analyzing software for windows. Harmonic parameters are analyzed using correlation signal processing techniques based on the correlation between voltage and current waveforms. Analysis results are visualized by 3-D current coordinates, and it is compared and evaluated with conventional time/frequency domain. To verify the validity of the proposed system, 1/4HP capacitor run type single phase induction motor and thyristor speed controller is used for analyzing. Harmonic parameters of motor drive system is analyzed and verified, with varying fire angle of thyristor speed controller, and the proposed approach is to confirm validity.

• Journal of Power Electronics
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• v.10 no.4
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• pp.412-418
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• 2010

This paper proposes a new algorithm to generate a reference signal for an active power filter using a sliding-window FFT operation to improve the steady-state performance of the active power filter. In the proposed algorithm the sliding-window FFT operation is applied to the load current to generate the reference value for the compensating current. The magnitude and phase-angle for each order of harmonics are respectively averaged for 14 periods. Furthermore, the phase-angle delay for each order of harmonics passing through the controller is corrected in advance to improve the compensation performance. The steady-state and transient performance of the proposed algorithm was verified through computer simulations and experimental work with a hardware prototype. A single-phase active power filter with the proposed algorithm can offer a reduction in THD from 75% to 4% when it is applied to a non-linear load composed of a diode bridge and a RC circuit. The active power filter with the proposed reference generation method shows accurate harmonic compensation performance compared with previously developed methods, in which the THD of source current is higher than 5%.

• International Journal of Internet, Broadcasting and Communication
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• v.9 no.2
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• pp.58-63
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• 2017

The sound we hear is transmitted through the atmosphere. However, both the sound we want to hear and the surrounding sound are mixed, and noise is generated, and the sound is not clearly transmitted due to factors such as distance. In particular, in closed spaces like buildings, it is often difficult to hear sounds from outside because of the sound of reflection. People with hearing impairments, such as the elderly and the deaf, have a hard time hearing the sounds they want to hear. Thus, we are developing a hearing aid that can detect radio waves. To this end, we propose the development of a hearing aid that uses FM radio and Bluetooth. These devices are expected to be useful not only for the elderly and the deaf but also in situations where information is transmitted to a large number of people, such as students and tourists, in a large space. The main purpose of this device is to enable users to hear sound correctly without blind spots.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.3
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• pp.328-334
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• 1999

A fish pump makes very important roles in an automation system of an aquaculture farm, thus it has been used widely in order to transfer fishes from one place to the other place automatically. In spite of its significant roles, the efforts for developing performance and promoting efficiency of the fish pump are not sufficient yet. In this paper, a method which makes the fish pump automation system is suggested. Automation of the fish pump can be accomplished by using variable voltage and variable frequency inverter system including induction motors. Especially, very simple logic to generate Pulse width Modulation(PWM) wave to control induction motor efficiently and three steps speed control method to regulate liquid quantity of the fish pump simply are suggested. Owing to the simplifies speed control and PWM wave generation technique, a cheaper microprocessor, 80C196KC, than a digital signal Processor(DSP) can be used to operate control algorithm in induction motor systems for real time control Also, a new idea of remote control for the simplifies novel inverter system by Programmable logic Controller(PLC) without special output unit, digital to analog converter(D/A), is suggested in this paper. Consequently the function of reliability, availability and serviceability of the fish pump system are developed. It will be expected to contribute expanding of application of the fish pump in aquaculture farms because the system can reduce energy consumption and some difficulties according to manual operation prominently.