• Journal of Electrical Engineering and Technology
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• v.8 no.1
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• pp.176-182
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• 2013

In this study, we examine the tracking happen in a polyvinyl-chloride-sheathed flat cord (PVCSFC), which is widely used as a distribution cord. The study classifies the bridge current via the formed conductive paths during tracking in the PVCSFC. Further, it attempts to distinguish the characteristics of heat generation and heat transfer by kind of bridge current. When the PVCSFC is in the static state, the bridge currents flow only through the electrolyte bridge. In the case of the carbonized PVCSFC, the bridge currents flow through one or more conductive paths. One is the electrolyte bridge, the other is the bridge that is consisted electrolyte and carbonized insulation. Currents flowing through different conductive paths have different heat generation and transfer characteristics. As the bridge current flowing in the conductive path consisting of electrolyte and carbonized insulation increases, the temperature difference between the surface of the PVCSFC and ambient air also increases correspondingly.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.11
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• pp.619-623
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• 2004

We proposed the bridge type superconducting fault current limiter(SFCL) using switching operation of high-Tc superconducting(HTSC) thin film. The proposed bridge type SFCL consists of HTSC thin film, a diode bridge and a dc reactor. The controller for the operation of an interrupter is required in the conventional bridge type SFCL to prevent the continuous increase of fault current after a fault happens. On the other hand, the proposed bridge type SFCL can limit the fault current without the interrupter and the controller for its operation by the resistance generated when the gradually increased fault current exceeds HTSC thin film's critical current. We calculated the time when the gradually increased fault current started to be limited by the resistance generated in HTSC thin film after a fault happened and confirmed that it could be dependent on the amplitude of source voltage. The experimental results well agreed with the calculated ones from simulation.

• Structural Monitoring and Maintenance
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• v.2 no.3
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• pp.283-300
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• 2015

Visual condition inspections remain paramount to assessing the current deterioration status of a bridge and assigning remediation or maintenance tasks so as to ensure the ongoing serviceability of the structure. However, in recent years, there has been an increasing backlog of maintenance activities. Existing research reveals that this is attributable to the labour-intensive, subjective and disruptive nature of the current bridge inspection method. Current processes ultimately require lane closures, traffic guidance schemes and inspection equipment. This not only increases the whole-of-life costs of the bridge, but also increases the risk to the travelling public as issues affecting the structural integrity may go unaddressed. As a tool for bridge condition inspections, Unmanned Aerial Vehicles (UAVs) or, drones, offer considerable potential, allowing a bridge to be visually assessed without the need for inspectors to walk across the deck or utilise under-bridge inspection units. With current inspection processes placing additional strain on the existing bridge maintenance resources, the technology has the potential to significantly reduce the overall inspection costs and disruption caused to the travelling public. In addition to this, the use of automated aerial image capture enables engineers to better understand a situation through the 3D spatial context offered by UAV systems. However, the use of UAV for bridge inspection involves a number of critical issues to be resolved, including stability and accuracy of control, and safety to people. SLAM (Simultaneous Localisation and Mapping) is a technique that could be used by a UAV to build a map of the bridge underneath, while simultaneously determining its location on the constructed map. While there are considerable economic and risk-related benefits created through introducing entirely new ways of inspecting bridges and visualising information, there also remain hindrances to the wider deployment of UAVs. This study is to provide a context for use of UAVs for conducting visual bridge inspections, in addition to addressing the obstacles that are required to be overcome in order for the technology to be integrated into current practice.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.4
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• pp.15-21
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• 2002

This paper presents parallel operation of ZVT(Zero Voltage Transition) FUll Bridge Converter with Dynamic Current Shared Inductor. In the conventional method, CT(Current Transformer) have been used tn share the load current equally with converters. In this system, at parallel operation of ZVT Full Bridge Converter, dynamic current shared inductor divides the same current of unit converter and ZVT circuit aids to high efficiency. Superiority of the characteristics is verified through the experiment with a 2[㎾], 50[㎑] prototype converter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.7
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• pp.59-69
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• 2012

There are two types of inverters that are generally used in induction heating systems: voltage type inverters and high-frequency half-bridge inverters. This paper proposes a new resonant inverter for induction heating systems using the current type full-bridge method. The proposed method can remove capacitors at the input end, and enables unity power factor operation by preventing phase differences of voltage and current. Furthermore, Zero Voltage Switching (ZVS) which is in tune with current type inverter can be adopted and continuous power adjustment is possible through duty ratio changes and frequency modulation in switching operation. Simulations and experiments showed that the proposed current type full-bridge resonant inverter could be used for unity power factor control and ZVS operation in induction heating systems.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1593-1600
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• 2015

This paper proposes a novel compensation algorithm of current offset error for single-phase linear compressor in home appliances. In a half-bridge inverter, current offset error may cause unbalanced DC-link voltage when the DC-link is comprised of two serially connected capacitors. To compensate the current measurement error, the synchronous reference frame transformation is used for detecting the measurement error. When an offset error occurs in the output current of the half-bridge inverter, the d-axis current has a ripple with frequency equal to the fundamental frequency. With the use of a proportional-resonant controller, the ripple component can be removed, and offset error can be compensated. The proposed compensation method can easily be implemented without much computation and additional hardware circuit. The validity of the proposed algorithm is verified through experimental results.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.550-558
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• 2018

This paper presents the current limit strategy of voltage controller of delta-connected H-bridge static synchronous compensator (STATCOM) under an unbalanced voltage fault event. When phase to ground fault happens, the feasibility to heighten the magnitude of sagging phase voltage is considered by using symmetric transformation method in delta-structure STATCOM. And the efficiency to cover the maximum physical current limit of switching device is considered by using vector analysis method that calculate the zero sequence current for balancing the cluster energy in delta connected H-bridge STATCOM. The result is simple and obvious. Only positive sequence current has to be used to support the unbalanced voltage sag. Although the relationship between combination of the negative sequence voltage with current and zero sequence current is nonlinear, the more negative sequence current is supplying, the larger zero sequence current is required. From the full-model STATCOM system simulation, zero sequence current demand is identified according to a ratio of positive and negative sequence compensating current. When only positive sequence current support voltage sag, the least zero sequence current is needed.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.3
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• pp.280-289
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• 2015

A high-efficiency full-bridge DC-DC converter with a current-doubler rectifier and an asymmetric pulse-width modulation is proposed. Through the asymmetric pulse-width modulation, the proposed converter achieves zero-voltage switching of power switches without the circulating currents. The proposed converter reduces the output current ripple through the current-doubler rectifier. A control strategy is suggested for the proposed converter to charge battery banks. A constant current and constant voltage charging is performed. The proposed converter achieved a higher efficiency compared with the conventional full-bridge DC-DC converter with a phase-shift modulation. The performance of the proposed converter is evaluated by the experimental results for a 1.0 kW prototype circuit.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.169-172
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• 2004

This paper presents the Asymmetric Half-Bridge converter using current-doubler rectifier. Resonant conditions of the asymmetrical soft switching Half-Bridge converter is analyzed. Current-doubler converter has small voltage and current ripple. The comparison of topology compared to the secondary rectification for center-tap type and current-doubler type are discussed. Experimental result are obtained on a 5V, 20A DC/DC Half-Bridge converter MOSFET based prototype for the 100W.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.4
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• pp.265-271
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• 2000

A non-contact battery charger for cellular phone is designed using half-bridge series resonant converter. This converter utilizes series resonance to reduce the undesirable effect of large leakage inductance of the detachable transformer and ZVS operation can reduce switching loss and switching noise. In this paper, analysis and design procedure of half-bridge series resonant converter with detachable transformer is presented. The input voltage is 85VAC∼270VAC, and the output voltage and current is 4.1V and 800mA, respectively. Furthermore, a method of calculating the secondary current of the transformer to control the battery charging current in the constant current charging mode is proposed. The performance of the charger is verified through experiments.