• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.4
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• pp.278-286
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• 2008

This paper investigates the fault generation type and the cause of output interruptionsin bulky with $30^{\sim}500[KVA]$ double conversion UPS, and proposes the fault detection method to improve the reliability of power supply used in the critical load in industry. Identifies its existing way of detecting a quality of inverter output it to bypass when exceeds its expectation. Under a UPS managing system, when an inner (Power device, Controller, CPU) fault occurs it disrupts the power supply and these occurrences has been verified by the results of experiments and application results. To overcome these problems, the proposed method constructs independently a fault-detection, a bypass-control device and a triple power supply apart from the conventional UPS operation. Also the detection point is changed to the preceding of a circuit breaker, a reference of fault detection is modified to avoid any clash and the breaking equipment is attached to intercept a spread of accident. As a result of applications of these developed systems to 242 UPS which was installed purposefully to the communication power supply, the service errors has not occurred in the UPS for two years since 2006.

• Journal of Aerospace System Engineering
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• v.17 no.6
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• pp.100-107
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• 2023

Open-phase fault in a Permanent Magnet Synchronous Motor (PMSM) occurs due to disconnection of phases of motor windings or inverter switch failures. When an open-phase occurs, it leads to the generation of torque ripples and vibrations in the motor, which can have a critical impact on the safety of the vehicle (including aircraft) using a PMSM as an actuator. Therefore, rapid fault detection and classification are essential. This paper proposes a classification method for detecting open-phase faults and locating fault positions in a PMSM used in aircraft applications. The proposed approach uses an Extended Kalman Filter for fault diagnosis, and it subsequently classifies faults using a Multiple Model filter.

• Journal of IKEEE
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• v.26 no.1
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• pp.43-49
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• 2022

This paper compares the sensorless control performance according to the applied voltage waveform by injecting sinusoidal, triangular, and square waveform in the harmonic injection sensorless control method. By injecting various voltage shape waveform with a frequency of 1kHz, the error amount of the estimated angle for each waveform is compared and analyzed. For the experiment, the HILS(hardware in the loop simulation) system was used. The hardware is the control board, and the inverter and motor models implemented in Simulik are located in the real-time simulator. The control algorithm is implemented by the FPGA control board, which includes a PWM interrupt service routine with a frequency of 10 kHz, harmonic injection and position detection sensorless algorithm.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.5
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• pp.329-335
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• 2008

Recently, super high-speed motor drives have been available due to the development of power electronics technology And they are used in various fields of industry because of their advantages. This paper describes the control algorithm for a permanent magnet synchronous motor(PMSM) drive at the speed of 118,000r/min using DSP and IGBT inverter. Hall sensors are implemented to measure the rotor position and speed, and a speed observer is used to reduce the performance deterioration caused by the low resolution of hall sensors. To enhance the output power capacity in the high-speed operating region, a flux weakening controller which also can work as an anti-wind up controller is used. Computer simulations and experiments are peformed to validate the proposed method.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.2
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• pp.7-14
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• 2005

This paper presents a method to reduce torque ripple of brushless DC motor by compensating phase delay due to winding inductance. For considering torque ripple comes from the phase winding inductance, torque equation of one phase is derived as Fourier series that is function of the delay. From the equation, also the resultant equation that the current delay is compensated is derived. It is validated that the compensated torque has a form of Fourier series for rectangular wave that is ideal torque, and torque ripple is reduced, consequently. Experimental method for the compensation is realized by replacing switching pattern of inverter by pattern of compensated rotor position. The effectiveness of the proposed method to reduce torque ripple has been demonstrated by the simulation and experimental results using 3 phase 4 pole brushless DC moor.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.4 s.33
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• pp.7-11
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• 2004

In this paper, a $\lambda$/4 hairpin resonator is applied to reduce the size of planar resonators for a 2.4 GHz Band LTCC MLC bandpass filter. The $\lambda$/4 hairpin resonator operates as stepped impedance resonator (SIR) without changing the width of the planar resonator. It is composed of two sections those are parallel coupled line and transmission line. The characteristic impedance of two sections is different each other. The design formulas of the bandpass filter using the coupling element at the arbitrary position are derived from even and odd-mode analysis. The formulas can take account of the arbitrary coupling of lumped and/or distributed resonators. The advantage of this filter is its abilities to change freely the coupling structure between two resonators. Experimental bandpass filters for 2.4 GHz Band are implemented and their performances are shown.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.8
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• pp.46-51
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• 2002

A new interleaved synchronous mirror delay(SMD) is proposed in order to reduce the circuit size and the power. The conventional interleaved SMD has multiple pairs of forward delay array(FDA) and backward delay away(BDA) in order to reduce the jitter. The proposed interleaved SMD. requires one FDA and one BDA by changing the position of multiplexer. Moreover, the proposed interleaved SMD solves the polarity problem with just one extra inverter. Simulation results show that about 30% power reduction and 40% area reduction are achieved in the proposed interleaved SMD. All circuit simulations and implementations are based on a 0.25um two-metal CMOS technology.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.3
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• pp.129-135
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• 2021

Switched Reluctance Motor (SRM) has a characteristic that the inductance changes very nonlinearly depending on the magnitude of the current and the relative position of the rotor and stator, and the torque is generated In consideration of these problems, many studies have been conducted on a topology for driving that can improve efficiency and performance in an existing asymmetric bridge converter in order to simplify the circuit and economic efficiency. Therefore, in this paper, we want to check the performance by comparing and analyzing each converter used by applying it as a topology for SRM driving. The driving converters applied to the comparison and analysis are Conventional C-dump, Modified C-dump, Energy efficient C-dump, Resonant C-dump converter with C-dump converter type structure and the most widely used asymmetric bridge converter and 6-Switch inverter that used for general motors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.9-17
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• 2020

Recently, RES (renewable energy source) projects have been spreading all over the world as an alternative to solve the shortage of energy and environmental problems caused by fossil fuel consumption. The Korean government also supported the policy and demonstration project to increase the proportion of renewable energy to 63.8[GW] until 2030, which is 20[%] of the total power generation. On the other hand, output loss of a PV array can occur when the surrounding high-rise buildings and trees shade a PV array. Therefore, this paper proposes an algorithm to improve the output loss of a PV array, which electrically changes a circuit configuration of PV modules by wiring and switching devices. Furthermore, this study modeled a PV system based on PSIM S/W, which was composed of a PV array, a circuit configuration device, and a grid-connected inverter. From the simulations results with the modeling and test device, the existing method showed no output when 50% of the shade occurs in PV modules. In contrast, the proposed method could produce the output because the voltage in the PV module could be restored to 246[V], and the operation efficiency of the PV system could be improved by the operation algorithm of the circuit configuration device.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.10
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• pp.1107-1116
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• 2007

In this paper, a broadband open stubs band pass filters which can suppress the second harmonics using Z-transform technique, is designed, fabricated and characterized. The proposed broadband filters integrate the band stop filter with the FSCS structure and ${\lambda}_g/4$ open stub in order to suppress the second harmonics. Due to insertion of BSF at input and output terminal, the size of the filter was increased in the conventional filter, however, in the proposed structure, the position of inverter that connects the stubs can be integrated between those stubs, thereby decreasing the size. So, it can be fabricated in the size of $18.7{\times}16.9mm^2$ which is smaller size than conventional one. The measured results of the proposed filters have center frequency of a 5.8 GHz with bandwidth of 95 %, insertion loss of 0.6 dB, return loss of 14 dB. The simulation results are consistent with measurement results. The filter is designed far X-band satellite communication and ITS applications.