• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1678-1687
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• 2013

This paper describes a prototype of 3-phase 3.3kV/220V 6kVA modular semiconductor transformer developed in the lab for feasibility study. The developed prototype is composed of three single-phase units coupled in Y-connection. Each single-phase unit with a rating of 1.9kV/127V 2kVA consists of a high-voltage high-frequency resonant AC-DC converter, a low-voltage hybrid-switching DC-DC converter, and a low-voltage hybrid-switching DC-AC converter. Also each single-phase unit has two DSP controllers to control converter operation and to acquire monitoring data. Monitoring system was developed based on LabView by using CAN communication link between the DSP controller and PC. Through various experimental analyses it was verified that the prototype operates with proper performance under normal and sag condition. The system efficiency can be improved by adopting optimal design and replacing the IGBT switch with the SiC MOSFET switch. The developed prototype confirms a possibility to build a commercial high-voltage high-power semiconductor transformer by increasing the number of series-connected converter modules in high-voltage side and improving the performance of switching element.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.2
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• pp.166-171
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• 2015

This paper shows the design of operational flight program(OFP) using model-based design(MBD) method which is used in various engineering fields to reduce time and flight risks for development. The verification of OFP for DO-178C guidelines carry out by a model advisor function of simulink. The flight control logic on simulink is converted into C-language by auto code generation tool from, then it is implemented on 32bit digital signal processor(DSP). The verifications of flight control algorithm on various weather conditions are performed by the HILS system with Flight simulator program, X-plane.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.5
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• pp.29-38
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• 1985

In this paper we have designed and implemented in real time a simple, efficient and flexible AOPCM cosec using a high speed digital processor, NEC 7720. For ADPCM system, we have used an instantaneous adaptive quantizer and a first-order fixed predictor. The software for NEC 7720 has been developed and it was found that the NEC 7720 was capable of performing the entire ADPCAt algorithm for 4 channels in real time as optimizing the program. Computer simulation has born made to investigate a computational accuracr of NEC 7720 and to de-termine necessary parameters for a ADPCM codec. Real telephone speech, RC-shaped Gaussian noise and 1004 Hz tone signal were used for simulation. In simulation, the parameters werc optimized from the computed SNR and the informal listening test. The developed software was tested in real time operation using a hardware emulator for NEC 7720. It took a maximum 23.25$\mu$s to encode one sample and 113.5$\mu$s, including all the necessary 1/0 operations, to encode 4 channels. In the case of decoding process, it took 24.75$\mu$s to decode one sample and 119.5$\mu$s to decode 4 channels.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.2
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• pp.303-308
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• 2001

An objection of this study is to develop a high stable measuring circuits and a analytic system for radioactive pulses. The proposed system consists of a pulse detection units for neutrons and gamma-rays a programmable high voltage supply unit and a digital signal processor. The programmable high voltage supply unit designed can generate DC voltage up to 1,500 V at 5 V input and have a series voltage regulator to maintain the output voltage constantly, resulting in less than 1.63% of voltage regulation. The pulse detection parts consists of an active integrator, a pole-zero circuit, and a 3-stage amplifier of 60 dB, and its frequency bandwidth is from 37 Hz to 300 kHzAlso, pulse height distribution in accordance with pulse counts is important data in analyzing radioactive pulses. In this study, A/D convertor (12bit, 100ms) and DSP (TMS320C31-60) are used to analyze the pulse height, and the analytic system is designed to be operated in PC-base.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2109-2116
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• 2014

This paper presents the implementation and design of the advanced WI-FI systems with beam-forming antenna that radiate their power to the direction of user equipment to improve the overall throughput, contrast to the general WI-FI systems equipped with omni-antenna. The system consists of patch array antenna, DSP, FPGA, and Qualcomm's commercial chip. The beam-forming system on the FPGA utilizes the packet information from Qualcomm's commercial chip to control the phase shifters and attenuators of the patch array antenna. The PCI express interface has been used to maximize the communication speed between DSP and FPGA. The directions of arrival of users are managed using the database, and each user is distinguished by the MAC address given from the packet information. When the system wants to transmit a packet to one user, it forms beams to the direction of arrival of the corresponding user stored in the database to maximize the throughput. Directions of arrival of users are estimated using the received preamble in the packet to make its SINR as high as possible. The proposed beam-forming system was implemented using an FPGA and Qualcommm's commercial chip together. The implemented system showed considerable throughput improvement over the existing general AP system with omni-directional antenna in the multi-user communication environment.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.3
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• pp.188-198
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• 2010

Recently, as the demand of the environmental-friendly energy storage system such as an electric double-layer condenser increases, that of the bidirectional charger/discharger for the systems also increases. However, when charging/discharging mode-change occurs, the charger/discharger employing a bi-directional DC-DC converter with a commercialized analog controller has a complex circuit scheme, and a poor transient response. On the other hand, if a single digital controller is used for the bi-directional mode, the system performances can be improved by application of an advanced power-processing algorithm. In the paper, an environmental-friendly power storage systems including an Electric Double Layer Capacitor(EDLC) banks were developed with a bi-directional buck-boost converter and a digital signal processor (TMS320F28335). A simulation test-bed was realized and tested by MATLAB Simulink, and the hardware experiment was performed which shows that the dynamic response was improved such as the simulation results.

• Journal of Electrical Engineering and Technology
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• v.7 no.4
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• pp.513-523
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• 2012

For precisely regulating the speed of a permanent magnet synchronous motor system with unknown load torque disturbance and disturbance inputs, an LMI-based sliding mode control scheme is proposed in this paper. After a brief review of the PMSM mathematical model, the sliding mode control law is designed in terms of linear matrix inequalities (LMIs). By adding an extended observer which estimates the unknown load torque, the proposed speed tracking controller can guarantee a good control performance. The stability of the proposed control system is proven through the reachability condition and an approximate method to implement the chattering reduction is also presented. The proposed control algorithm is implemented by using a digital signal processor (DSP) TMS320F28335. The simulation and experimental results verify that the proposed methodology achieves a more robust performance and a faster dynamic response than the conventional linear PI control method in the presence of PMSM parameter uncertainties and unknown external noises.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1838-1844
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• 2011

In this paper, the propulsion control of a high-speed maglev train is studied. Electromagnetic suspension is used to levitate the vehicle, and linear synchronous motors (LSM) are used for propulsion. In general, a low-speed maglev train uses a linear induction motor (LIM) for propulsion that is operated under 300[km/h] due to the power-collecting and end-effect problem of LIM. In case of the high-speed maglev train over 500[km/h], a linear synchronous motor (LSM) is more suitable than LIM because of a high-efficiency and high-output properties. An optical barcode positioning system is used to obtain the absolute position of the vehicle due to its wide working distance and ease of installation. However, because the vehicle is working completely contactless, the position measured on the vehicle has to be transmitted to the ground for propulsion control via wireless communication. For this purpose, Bluetooth is used and communication hardware is designed. A propulsion controller using a digital signal processor (DSP) in the ground receives the delayed position information, calculates the required currents, and controls the stator currents through inverters. The performance of the implemented propulsion control is analyzed with a small maglev train which was manufactured for experiments, and the applicability of the high-speed maglev train will be explored.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.2
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• pp.89-96
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• 2016

This paper describes the design of a force measurement and communication system for the force measuring system in industrial robots. The force measurement and communication system is composed of a multi-axis force sensor and a controller for measuring the forces (x-direction force, y-direction force and z-direction force) and sending the measured forces to the robot's controller (PLC: Programmable Logic Controller). In this paper, the force measurement and communication system was designed and fabricated by using a DSP (Digital Signal Processor). An environment test and a grinding and deburring test using an industrial robot with the force measurement and communication system with three-axis force sensor were carried out to characterize the system. The tests showed that the system could safely measure the forces from the three-axis force sensor and send the measured forces to the industrial robot's controller while the grinding and deburring test was performed. Thus, it is thought that the fabricated force measurement and communication system could be used for controlling the force for an industrial robot's grinding and deburring.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.4
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• pp.457-463
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• 2012

Cascaded H-bridge multilevel inverters shows a useful circuit configuration to increase the number of output voltage levels to obtain high quality output voltage. By applying the concept of the power of three to dc voltage sources, it can increase the number of output voltage levels effectively. To realize this concept, two approaches may be considered. One is to use independent dc voltage sources pre-scaled in the power of three, and the other is to use instantaneous dc voltage sources generated from a cascaded transformer, which has the secondary turn-ratios scaled in the power of three in sequence. A common feature in both approaches is to use the concept of the power of three for dc voltage sources, and a point of difference is whether it adopts a low frequency transformer or not, and where the transformer is located. According to the difference, application areas are limited and show different characteristics on THD of output voltages. We compare and analyze both approaches for their circuit configurations, voltage level generating method, THD characteristics of output voltage, efficiency, application areas, limitations, and other characteristics by experiments using 500 [W] prototypes when they generate a 27-level output voltage.