• Proceedings of the Korean Vacuum Society Conference
• /
• 2007.08a
• /
• pp.175-175
• /
• 2007

• Journal of Drive and Control
• /
• v.15 no.4
• /
• pp.108-112
• /
• 2018

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.38 no.6
• /
• pp.441-450
• /
• 1989

A control technique for current-fed filters is proposed which not only eliminates the harmonic current, but also controls the reactive power at the ac sides of PWM inverter-induction motor drive system. Injecting the proposed PWM current enables the harmonic components of orders not greater than the number of pulses per half-cycle to be removed completely. Also it enables the input fundamental power factor to become unity and hence total input power factor can be improved greatly. Digital simulation is performed to investigate the theoretical output characteristics of the current-fed filters by the proposed control technique.

• Journal of Power Electronics
• /
• v.5 no.2
• /
• pp.151-159
• /
• 2005

The errors generated from current measurement paths are inevitable, and they can be divided into two categories: offset error and scaling error. The current data including these errors cause periodic speed ripples which are one and two times the stator electrical frequency respectively. Since these undesirable ripples bring about harmful influences to motor driving systems, a compensation algorithm must be introduced to the control algorithm of the motor drive. In this paper, a new compensation algorithm is proposed. The signal of the integrator output of the d-axis current regulator is chosen and processed to compensate for the current measurement errors. Usually the d-axis current command is zero or constant to acquire the maximum torque or unity power factor in the ac drive system, and the output of the d-axis current regulator is nearly zero or constant as well. If the stator currents include the offset and scaling errors, the respective motor speed produces a ripple related to one and two times the stator electrical frequency, and the signal of the integrator output of the d-axis current regulator also produces the ripple as the motor speed does. The compensation of the current measurement errors is easily implemented to smooth the signal of the integrator output of the d-axis current regulator by subtracting the DC offset value or rescaling the gain of the hall sensor. Therefore, the proposed algorithm has several features: the robustness in the variation of the mechanical parameters, the application of the steady and transient state, the ease of implementation, and less computation time. The MATLAB simulation and experimental results are shown in order to verify the validity of the proposed current compensating algorithm.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.12 no.5
• /
• pp.507-511
• /
• 2019

The use of regenerative energy in AC drive systems has been an issue since the system became an industry standard in the 1990s. According to the quantity of the regenerative energy, the braking resistor in the case of low capacity was common. However the use of such low amount of energy is actively discussed, and the method of mounting the regenerative converter is becoming popular. In this paper, an isolated regenerative converter for reducing the circulating current which is mentioned as the biggest disadvantage of the conventional power regenerative converter system is proposed. In order to save energy, employing a power regenerative converter system for utilizing regenerative energy in an AC drive system is common. However due to the structure of the system, a circulating current is generated, which inevitably causes a decrease in efficiency. In this paper, an isolated regenerative power converter system is proposed to solve the circulating current and computer simulation to verify the possibility. The simulation results show that 20% of the circulating current of the conventional system does not appear in the proposed system, and the validity of the proposed system is confirmed.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.1732-1735
• /
• 2003

In this paper, a DSP-based test apparatus for Control Rod Drive Mechanism (CRDM) that is used in nuclear power plants is described. Using this apparatus, we can test the mechanical and electrical characteristics of CRDM and obtain some information about how to improve the CRDM further and how to design a power controller to actuate the CRDM. Since firing angles can be directly applied to the gate-drive circuits of thyristors in the power controller by using this apparatus, the maximum and minimum values of firing angles within available limits are easily measured. Also step-current inputs help us investigate each coil's response characteristics. Therefore, we can easily find the range of control gains which enables a stable CRDM operation in insertion and withdrawal actions at high speed, mid speed, and low speed. Since this apparatus has a test mode in which an insertion or withdrawal action is divided into several phases so that the current command for each phase is given step by step, we may judge whether the CRDM works as expected or not. We also describe a fault detection capability of the test apparatus for the power controller by using discrete Fourier transform.

• Proceedings of the KIEE Conference
• /
• 2006.04b
• /
• pp.155-157
• /
• 2006

The paper is proposed maximum torque control of SynRM drive using adaptive learning mechanism-fuzzy neural network(ALM-FNN) controller and artificial neural network(ANN). The control method is applicable over the entire speed range and considered the limits of the inverter's current and voltage rated value. For each control mode, a condition that determines the optimal d-axis current $i_d$ for maximum torque operation is derived. The proposed control algorithm is applied to SynRM drive system controlled ALM-FNN and ANN controller, the operating characteristics controlled by maximum torque control are examined in detail. Also, this paper is proposed the analysis results to verify the effectiveness of the ALM-FNN and ANN controller.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.27 no.1
• /
• pp.20-27
• /
• 2017

This study investigated the problems in current practice of drive-train resonance analysis procedure and suggested solutions. The first problem is the resonance occurrence at the un-identified resonance point by the current practice, as for a solution the force spectrum analysis for each critical force transmitting component was suggested. The second one is the inaccurate estimation of potential resonance point in eigenfrequency analysis because of the non-consideration about the eigenfrequency dependency on rotor-speed, the fine linearization at each rotor speed point all over operational range was proposed to account for the affection. Lastly the insufficient time for resonance activation under run-up simulation condition was recognized as a problem in resonance load increasing analysis, as an alternative, steady state condition was suggested to estimate the maximum load increasing level.

• Journal of Power System Engineering
• /
• v.17 no.2
• /
• pp.38-45
• /
• 2013

In this study, for carrying out the spray and combustion experiment using a Common Rail Direct Injection(CRDI) system, the controller was fabricated to drive a high speed camera, a injector and a laser beam sequentially at a low cost. CB280 module of one-chip micro processer was used for the controller. In order to confirm responsibility and utility of the controller, the current drive performance, the spray behavior and the injection rate were tested and analyzed under various experimental conditions. As this research results, we found that the fabricated controller was able to control the devices for the spray experiment precisely with the input value in program and it had the dynamic load responsibility and repetition. Also, we found that the injection rates of our experimental results were higher than those of others at the same injection pressure and the controller connected with the laser system and the data acquisition system had validity for carrying out the spray visualization experiment.

• Proceedings of the KIPE Conference
• /
• 2002.07a
• /
• pp.707-710
• /
• 2002

A 120kV/70A high voltage switch has been installed at Korea Atomic Energy Research Institute in Taejon to supply power with Korea Superconducting Tokamak Advanced Research (KSTAR) Neutral Beam Injection (NBI) system. NBI system requires fast cutoff of the power supply voltage for protection of the grid when arc detected and fast turn-on the voltage for sustaining the beam current. Therefore the high voltage switch and arc current detection circuit are important part of the NBI power supply and there are much need for high voltage solid state switches in NBI system and a broad area of applications. This switch consisted of 100 series connected MOSFETs and adopted the proposed simple and reliable gate drive circuit without bias supply, Various results taken during the commissioning phase with a 100kW resistive load and NBI source are shown. This paper presents the detailed design of 120kV/70A high voltage MOSFETs switch and simple gate drive circuit. Problems with the high voltage switch and gate driver and solutions are also presented.