• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.146-148
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• 2006

The aim of the paper is to design the PLS(Plasma Lighting System) driving inverter circuit with optimal efficiency. In general, it is known that the PLS driven by a pulse has a higher light-conversion efficiency. There are the Class-E type resonant inverter and the semi-bridge inverter as a circuit which can make a pulse with low duty ratio. In this paper, we analyze the losses of the above two circuits. To verify the loss analysis, the inverter circuit with 220V 380W input consumption is manufactured and tested. Throughout the experimental results, the high efficiency PLS system has confirmed.

• Journal of Power Electronics
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• v.9 no.5
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• pp.679-690
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• 2009

The paper presents a new photovoltaic inverter for stand-alone induction motor application. The proposed system is composed of two stages. First stage is for the photovoltaic dc power feeding and second stage is dedicated to the motor-inverter subsystem and control technique. A direct torque control (DTC) with a novel switching strategy for motor torque ripple minimization is introduced. The novel DTC strategy is based on selecting a suitable voltage vector group for motor torque ripple minimization. A three-level voltage source inverter (VSI) is used instead of a two level inverter because the first has more available vectors and lower ripples in the output current and flux than the second, thus it has lower torque ripples. The photovoltaic array and battery bank are sized and the configuration is indicated based on sun-hour methodology. Simulation results show a comparison between three systems; two level VSI with conventional DTC strategy, three level VSI with conventional DTC, and the proposed system that has a novel DTC switching strategy applied to three level VSI. The results show that the proposed system has lower ripples in the current, flux and torque of the motor.

• Journal of the Korean Professional Engineers Association
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• v.33 no.1
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• pp.94-105
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• 2000

The purpose of this paper is to obtain the improved reliability and optimal control of the half-bridge inverter for induction heating system. Parasitic inductance components within the inverter circuit for induction heating including the loss-less turn-off snubber capacitor considerably affect stable operation and noise level of the system. This paper analyzes the effect of the inductance in detail and presents a new snubber configuration suitable for the half-bridge inverter to effectively reduce it. In the half-bridge inverter for induction heating the capacity of the loss-less snubber capacitor determines the switching losses because the zero voltage turn-on switching is used. However, the increase of the capacitor is limited by the system specifications, so that it is not easy work to reduce the switching loss. To effectively overcome the limitation, this paper introduces an active auxiliary resonant circuit suitable for the half-bridge inverter circuit, which operates actively according to the variation of load condition. It is also one of the most important study issues for the half-bridge inverter driven induction heater that the development of optimal control scheme considering varied load condition should be achieved. The control strategy ensures a very stable operation of overall inverter system and zero voltage turn-on switching irrespective of sensitive load parameter variations, in particular, even under the non-magnetic materials.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.325-328
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• 2005

EEFLs are mostly driven by sinusoidal wave driving method although EEFLs (External Electrode Fluorescent Lamps) are driven by both sinusoidal wave and square wave. The sinusoidal driving method reduces the cost and allows more power efficiency since this driving method can reduce the voltage stress of EEFL inverter switches and achieve the soft switching of the switches. And a transformer should be used in the inverter since the high voltage should be applied to the both ends of EEFL to turn on the lamp. However, the power loss mainly occurs at the transformer in the sinusoidal wave driving method. In order to remove the transformer which makes the power loss, a new method is presented. In this paper, the square wave is applied directly to the both ends of EEFL by a proposed two-stage inverter. Moreover, the luminance and power efficiency will be compared between the common sinusoidal wave driving method and square wave driving method.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.2
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• pp.217-227
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• 2000

Although inverter-driven hydraulic elevators(HEL's) have advantages over traditional valve-controlled HEL's energy efficiency and performance they need robustness in performance and stability to accomodate nonlinearities big parametric variations and resonances in mechanical-hydraulic inner system. In this paper a robust controller based on DGKF/$\mu$ mixed approach is applied to a HEL system with carring capacity of 24 persons for Incheon International Airport. The results of a test tower(T/T) has shown good ro-bustness in performance and stability of the proposed controller thereby proving a feasibility of this robust controller-based approach for other HEL problems.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.2
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• pp.271-271
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• 2000

Although inverter-driven hydraulic elevators(HEL's) have advantages over traditional valve-controlled HEL's energy efficiency and performance they need robustness in performance and stability to accomodate nonlinearities big parametric variations and resonances in mechanical-hydraulic inner system. In this paper a robust controller based on DGKF/μ mixed approach is applied to a HEL system with carring capacity of 24 persons for Incheon International Airport. The results of a test tower(T/T) has shown good ro-bustness in performance and stability of the proposed controller thereby proving a feasibility of this robust controller-based approach for other HEL problems.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.3
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• pp.107-118
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• 1995

The characteristics of the current waveforms and 3$\Phi$ power waveforms of the variable speed 3$\Phi$ AC motor system driven by the single-pulse PWM investigated in this paper. The system is composed of a digital bridge inverter and low pass LC filter. It is confirmed that current waveforms and 3$\Phi$ power waveforms can be improved by utilizing the high order low pass LC filter than that of lower order through computer simulation. Also, we propose the low pass LC filter revised from the conventional LC filter.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.7
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• pp.649-658
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• 2000

Thermodynamic modeling of low-pressure scroll compressor was developed by combining continuity and energy conservation equation. Suction gas heating was considered using energy balance inside the low pressure shell. Pressure, temperature and mass of refrigerant-22 as a function of orbiting angle were calculated by solving the governing equations using fourth order Rung-Kutta scheme. Motor efficiency was taken by experiments with a variation of frequency. The developed model was applied to the analysis of an inverter driven scroll compressor with a variation of frequency, pressure ratio and operating conditions. The model was verified with the experimental results at the same operating conditions. The developed model was adequate to predict performance of the inverter driven scroll compressor as a function of operating conditions. Calculated parameters from the model were discharge temperature, mass flow rate, power input, COP, and thermodynamic properties with respect to orbiting angle. To enhance the performance of a scroll compressor, it is essential to diminish leakage at low frequency level and improve the mechanical efficiency at high frequency level.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.539-540
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• 2002

A self-discharge in multi-EEFLs and CCFLs has been found to provide a high luminance and efficiency. With a fast rising and falling times of $2{mu}s$, and the peak voltage over 1.6KV, the self-discharge occurs in EEFLs and CCFLs driven by a full bridge switching inverter. Particularly in CCFLs connected with a typical value of ballast capacitance, a self-discharge follows by the main discharge when the voltage falls to the ground.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.1
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• pp.32-41
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• 1992

This paper presents a comprehensive study on the stability of several control schemes for the induction motor driven by current source inverters. A stator voltage controlled current source inverter drive system without a speed sensor is investigated in order to find appropriate control schemes, which are primarily based on direct or, alternatively, indirect frequency control scheme. It can be seen, especially that an introduction of the indirect frequency control method improves the inherent instability of the current source inverter drive system for the induction motor. The overall control systems with either voltage control loop or current and voltage control loops in addition to each frequency control scheme, are analyzed by utilizing the root locus method and simulated by computer to show the validity of this analysis.