• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.4
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• pp.372-376
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• 2010

Electrolytic capacitors have been widely used in power electronics system because of the features of large capacitance, small size, high-voltage, and low-cost. Electrolytic capacitors, which is most of the time affected by aging effect, plays a very important role for the power electronics system quality and reliability. Therefore it is important to estimate the parameter of an electrolytic capacitor to predict the failure. The estimation of the equivalent series resistance(ESR) is important parameter in life condition monitoring of electrolytic capacitor. This paper proposes a simple technique to measure the ESR of an electrolytic capacitor. This method uses a switching DC/DC boost converter to measure the DC Bus capacitor ESR of power converter. Main advantage of the proposed method is very simple in technique, consumes very little time and requires only simple instruments. Simulation results are shown to verify the performance of the proposed method.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.5 no.3
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• pp.54-63
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• 1991

This paper describes an effort to develope a microcomputer-based parameter measurement system for a brushless DC motor. Back EMF equation is derived from back EMF waveform of a brushless DC motor. To minimize error the due to the ripple component in the measured armature current, digital averaging filter is employed. The whole identification process of signal generation, measurement parameter determination is fully automated. A new identification algorithm for the brushless DC motor parameters is developed. New parameter correction method is proposed using the deadzone current and the time to reach the peak current. In the proposed correction method, the measured current is in excellent agreement with the estimated current.

• Journal of the Semiconductor & Display Technology
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• v.3 no.1
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• pp.1-7
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• 2004

In this paper, we have developed the DC parameters test system which inspects the properties of DC parameters for semiconductor products. The developed system is interfaced by IBM-PC. It is consisted of CPLD part, ADC(Analog-to-Digital Converter), DAC(Digital-to-Analog Converter), voltage/current source, variable resistor and measurement part. In the proposed system, we have designed the constant voltage source and the constant current source in a part. In the comparison of results, the results of the simulation are very similar to the ones of the implementation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.8
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• pp.517-524
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• 2004

In this paper, a novel zero-voltage-switching(ZVS) resonant DC-DC converter is proposed. It is composed of two symmetrical active-clamped circuits, the converter can be achieve ZVS in each switches. Also, active clamp capacitor ratios($\alpha$) of proposed circuit can be reduce a peak stress of switching voltage for each main switch. Simulation results using Pspice 9.2 ver and $C^{++}$ characteristic analysis show a provement for the validity of theoretical analysis. The analysis of the proposed Current-Fed Push Pull type DC-DC converter is generally described by using normalized parameter, and achieved an evaluated characteristic values which is needed to design a circuit. We confirm a rightfulness theoretical analysis by comparing a theoretical values and experimental values obtained from experiment using MOSFET as switching devices.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.12
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• pp.1147-1154
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• 2014

Generally, motor controller design is based on its motor dynamics. Therefore, it requires precise information of its motor dynamics. However, most of the low cost DC motors, which are widely used in industries and academia, are provided without such precise information. Even if it is given, the information is mostly imprecise. Following circumstances require one to calculate the motor dynamics information for oneself. This paper presents a simple method to readily apprehend the DC motor dynamics. First, how to establish the model of DC motor dynamics along with the model parameter identification is presented. Then, the parameter values are finetuned until the simulation response based on the dynamics model is close to the experimental response of the motor. Finally, the controller is designed with the established dynamics model. The validity of the designed controller is confirmed by the comparison of the experiment and simulation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.3
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• pp.131-138
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• 1999

Generally, the digital controller has many advantages such as high precision, robustness to electrical noise, capability of flexible programming and fast response to the load variation. In this study, we have established proper mathematical equivalent model of Brushless DC (BLDC) motor and estimated the motor parameter by means of the back-emf measurement as being the step input to the controlled target BLDC motor. And the validity of proposed estimation method is confirmed by the test result of step response. As well, we have designed the reasonable digital controller as a consequence of the root locus method which is obtained from the open-loop transfer function of BLDC motor with hall sensor, and the determination of control gain for variable speed control. Here, revised Ziegler-Nichols tuning method is applied for the proper digital gain establishment, and the system stability is verified by the frequency domain analysis with Bode-plot and experimentation.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.165-166
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• 1998

A multi-parameter neuro muscular electrical simulator (NMES) system was developed to be used to find the optimal parameter condition in obtaining maximum muscle power and minimal fatigue. Since the performance of NMES is mainly determined by the characteristic of its output-stage circuit, we implemented 3 different circuits and compared output characteristics of them. Three amplifier circuits are; 1) a resonant switching converter, 2) a linear amplifier with a transformer, and 3) a step-up DC/DC converter with a high-voltage linear amplifier. Experimental results showed that the step up DC/DC converter with a high-voltage linear amplifier has the best performance.

• Journal of information and communication convergence engineering
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• v.6 no.2
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• pp.154-157
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• 2008

A class-E RF(Radio Frequency) power amplifier for wireless application is designed using standard CMOS technology. To drive the class-E power amplifier, a class-F RF power amplifier is used and the reliability characteristics are studied with a class-E load network. The reliability characteristic is improved when a finite-DC feed inductor is used instead of an RF choke with the load. After one year of operating, when the load is an RF choke the output current and voltage of the power amplifier decrease about 17% compared to initial values. But when the load is a finite DC-feed inductor the output current and voltage decrease 9.7%. The S-parameter such as input reflection coefficient(S11) and the forward transmission scattering parameter(S21) is simulated with the stress time. In a finite DC-feed inductor the characteristics of S-parameter are changed slightly compared to an RF-choke inductor. From the simulation results, the class-E power amplifier with a finite DC-feed inductor shows superior reliability characteristics compared to power amplifier using an RF choke.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.451-456
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• 1991

A robust position control scheme for DC Motor is proposed based on Fuzzy Acceleration Control. Proposed control system has the similar structure that Y. Hori proposed. But the PI type acceleration controller of it is replaced by Fuzzy Logic Controller(FLC) which is known to be robust to the operating point and parameter variations. By the simulation study for a real DC Motor, we have slowed the superiority to the continuous PI acceleration controller in the view point of robustness to the operating point and parameter variations.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.217-220
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• 2001

CaN(gallium nitride) MODFET(modulation doped field effect transistor) large signal model was studied using Modified Materka-Kacprzak large signal MODFET model. using the Dambrine's method［3, at 45MHz-40㎓, Measured S-parameter and DC characteristics. based on measuring results, small signal parameter extraction was conducted. by the cold FET［4］method, measured parasitic elements were de-embedding. Extracted small signal parameters were modeled using modified Materka model, a sort of fitting function reproduce measuring results. to confirm conducted large signal modeling, modeled GaN MODFET's DC, S-parameter and Power characteristics were compared to measured results, respectively. by results were represented comparatively agreement, this paper showed that modified Materka model was useful in the GaN MODFET large signal modeling.