• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.113-116
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• 1988

In this paper, We Proposed a new Thyristor-FET hybrid type high-Frequency inverter circuit topology. Concerning the proposed high-frequency inverter. We applied the normalized parameters to the characteristic analysis of steady-state at the resistive load.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.11
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• pp.1491-1496
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• 2014

VSC-HVDC system is vulnerable to a DC fault because the fault current can be injected from AC system to DC system during the fault. Therefore, DC circuit breaker is required to isolate faults in VSC-HVDC system. The inverse current injection method of circuit breaker has been considered as DC circuit breaker. However, the topology has drawback that the breaking time is longer than hybrid circuit breaker using semiconductor devices. In order to solve this problem, this paper proposes an improved topology of circuit breaker based on inverse current injection method. In addition, the proposed topology will be compared with the existing topology. And we will verify its effects by using the simulation results.

• Journal of Power Electronics
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• v.15 no.1
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• pp.31-38
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• 2015

In this paper, a buck-boost type battery charger is developed for charging battery set with a lower voltage. This battery charger is configured by a rectifier circuit, an integrated boost/buck power converter and a switched capacitors circuit. A boost power converter and a buck power converter sharing a common power electronic switch are integrated to form the integrated boost/buck power converter. By controlling the common power electronic switch, the battery charger performs a hybrid constant-current/constant-voltage charging method and gets a high input power factor. Accordingly, both the power circuit and the control circuit of the developed battery charger are simplified. The switched capacitors circuit is applied to be the output of the boost converter and the input of the buck converter. The switched capacitors circuit can change its voltage according to the utility voltage so as to reduce the step-up voltage gain of the boost converter when the utility voltage is small. Hence, the power efficiency of a buck-boost type battery charger can be improved. Moreover, the step-down voltage gain of the buck power converter is reduced to increase the controllable range of the duty ratio for the common power electronic switch. A prototype is developed and tested to verify the performance of the proposed battery charger.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.143.2-143.2
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• 2010

Therefore, with this development assignment we'd like to develop the hybrid system combining 800W DMFC (Direct Methanol Fuel Cell) and 1.6kW of Lithium secondary battery pack which can be applied to the most common small cart. a scooter, to secure the development capability of hundreds of Watts DMFC, the high-capacity Lithium secondary battery pack, the technology of BMS (Battery Management System) and the development technology of hybrid system. DMFC, in fact, has lower energy efficiency than PEMFC (Polymer Electrolyte Membrane Fuel Cell); however, it has several advantages in terms of fuel storage and use. It is pretty easy to be stored and used without any additional colling and heating devices because of its insensitive liquid methanol to temperature. In conclusion, DMFC system is the most suitable device for small mobile vehicles.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.19-22
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• 2004

This paper implemented 2.14GHz band Adaptive Hybrid Doherty (AHD) amplifier, as well as, wished to improve the high power characteristics and efficiency by composing bias adjustment circuit with LDMOS. Finally, through CAE, confirmed that AHD amplifier have superior performance than hybrid balanced amplifier. Superior characteristics of AHD amplifier is expected to affect immensely in amplifier field hereafter.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.782-787
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• 2002

In optical disk drives (ODD), the demands of high data density and high speed have been increasing rapidly to achieve high data capacity and data transfer rate. The short wavelength laser, High NA objective lens, and high track following performance are needed to raise data density and data rate. For high-performance actuator, the improvement of linearity and acceleration become more important. Also, 3-axis actuator for active tilt compensation is introduced to overcome the decrease in disk tilt tolerance which is induced by short wavelength laser. In this paper, a hybrid type 3-axis actuator is presented and a new yoke structure, which can reduce the interaction between yoke and moving magnet, is designed to keep the efficiency of magnetic circuit. Experimental results show the validity of the yoke in the hybrid type actuator.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1174-1175
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• 2008

A operation scheme to regulate the active power output of the hybrid system consisted of a doubly fed induction generator(DFIG) and a fuel-cell are presented. The power output of the wind turbine fluctuates as the wind speed varies and the slip power between the rotor circuit and power converter varies as the rotor speed change. A fuel cell system can be individually operated and adjusted output power. In this paper, a fuel-cell is performed to regulate the active output power in comparison with the active power output of a DFIG. Based on PSCAD/EMTDC power system tools, we simulated a DFIG and a fuel cell and investigated about dynamics of the output power in hybrid system.

• Journal of Drive and Control
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• v.13 no.3
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• pp.53-66
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• 2016

New non-hybrid approaches to improve energy efficiency of construction machineries are reviewed in this paper. Hydraulic systems are classified into four classes according to Backe's classification and commercially promising new technologies are carefully chosen in each class. IMV, 3-Line CPR, Closed Circuit Displacement Control of Differential Cylinder, and Throttle-less Secondary Control are chosen as representative non-hybrid new technologies. Key principle of each technology is explained and representative references which run through each technology are selected. Advantages and weaknesses of each technology are discussed and compared from the view point of construction machinery manufacturers.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.1
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• pp.1-9
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• 1989

In this paper, an efficient method of a hybrid stepping motor is proposed using permeance method. To be specific, hybrid stepping motor is modelled firstly as an equivalent nonlinear magnetic circuit including the saturation effects of iron parts, and then the static holding torque of the motor is calculated as a function of each design factor via Newton-Raphson's method. To show the validities of the proposed method, a prototype of hybrid stepping motor for 5 1/4 inches FDD header drive is made and tested in laboratory. As a result, the experimental data for the static holding torque is shown to be within 10% error compared with that of the simulated results.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3230-3232
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• 1999

In this paper describes the design and improvement of a hybrid module for dual slope A/D converter. Since the input voltage to be converted is very sensitive and small. A/D converter must have the temperature stability. low-drift, and the high-resolution the conversion. A dual slop A/D converter circuit which is controlled by microprocessoer has been developed to reduce the offset voltage and the drift characteristics of operation amplifiers, and to improve the A/D conversion speed. Also hybrid module has been adapted to obtain the to obtain the stable and accurate A/D conversion for low cost use. The evaluation of the designed hybrid module has been shown as having a good performance, which will give usefull application to the industrial measurements use.