Dong-Hwa Han

Design of Leakage Inductance in Resonant DC-DC Converter for Electric Vehicle Charger

In this paper, the electric charger with single phase PWM converter and a bidirectional half-bridge converter is proposed. A transformer leakage inductance is used for making resonance at the resonant converter, which can make switched current to be sinusoidal without extra inductive component. Both operating principle and design guideline are described in detail. The feasibility for the proposed design is verified through hardware implementation and the experimental results. Detailed results have been obtained to show several advantages such as the compact design and reduced switching losses for different values and conditions of leakage inductance and resonance cases.

Multi-level resonant push-pull converter for fuel cell system

In this paper, the development of high efficiency 1kw PCS (Power Conditioning System) for utility interactive residential generation by Fuel Cell. Generally the Fuel cell PCS consists of low-voltage DC/DC boost converter part and utility-interactive DC/AC inverter. The high efficiency Multi-level boost-up converter was suggested for high efficiency system. And design and experiment was researched using the grid-interactive inverter.

Study on Li-Battery charge control based on DC-grid

This paper suggests the Li-Battery fast charge system based on DC link. That is composed of 3phase PWM converter, PV boost converter and isolated full-bridge converter. This paper studies power control scheme of the entire system and how the rapid charging of the battery. The proposed system is supplied the power from not only grid by current control of the 3phase PWM converter but also MPPT(Maximum Power Point Tracking) control of PV system, and rapidly charge the Li-battery by CVCC method (constant voltage/constant current) of the isolated full-bridge converter.

Improving the Overall Efficiency for DC/DC Converter with LoV-HiC System

It is very important to improve the overall efficiency of systems with a source of power that has low-voltage high-current terminal characteristics such as fuel cells. A resonant converter is required for high efficiency systems. However, the peak value of the switches current is large in a resonant converter. This peak current requires a large number of switches and results in system failures. In this paper, an analysis and experiments of a resonant isolation push-pull converter are performed. A switching loss analysis is performed in order to compare losses between a resonant push pull converter and a hard switching push-pull converter. Specially, the conduction loss is studied based on the ratio between the resonant frequency and the switching frequency. In addition, a method for improving the efficiency is implemented with conventional HF insolation converters.

Improved RTGC system with voltage compensation converter to reduce fuel consumption

This paper presents improved Rubber Tyred Gantry Crane system with high power voltage compensated converter to save the fuel consumption. The RTGC system requires the power from diesel-engine. Significant fuel savings by reducing the engine speed can be achieved, because all of operation modes except hoisting are required lower power than rated value of engine. When low speed operation output voltage of generator is decrease until acceptable range of motor driver inverters and auxiliary load supplier. According to power demand engine speed is varying from 20 to 60Hz, and voltage is varying between 210Vac and 480Vac. When idle mode or low power operation dc/dc converter operates by constant output voltage control and inverters dc site voltage is compensated by it. This paper proposed 3-phase interleaved boost converter which has the same structure as the commercially available 3-phase inverter and current sharing capability. 400kW interleaved converter is designed and a performance of converter is evaluated through several experiments with a RTGC system. That system can cut down fuel consumption by 36% and 21.3% at idle and unidirectional load operation.

A photovoltaic power-generation system with peak power cut function

This paper presents a photovoltaic-peak power-cutting (PV-PPC) system capable of cutting peak load power. The proposed system is composed of a PV generator, DC–DC converter, storage battery, and an inverter. The function of the proposed PV-PPC system is to use PV energy to cut the peak load power in response to the change in the load demand and generating power. Four possible power flow scenarios are examined in detail through the bidirectional operation of the DC–DC converter and inverter, through the charging and discharging of the battery. The suggested PV-PPC system operation algorithm first selects the operational state by using differentiated charge and load information, with a simple structure to enable stopping in the case of system failure, and operates depending on the selected state. Then, the analysis modelling and operational control algorithm of the PV-PPC-generation system are performed in detail. Finally, the simulation and experimental results are presented to confirm the validity of the system.

Design and Test of ESS DC-DC Converter using Zinc-Bromine Redox Flow Battery for Stand-alone Microgrid

This paper proposes ESS DC-DC Converter using Redox Flow Battery (RFB) for stand-alone microgrid. Price, safety, expandability and dynamics are crucial in ESS. Reports show that Zinc-bromine (ZnBr) RFB is the best choice in ESS. Simple electrical ZnBr RFB model is obtained from charging test. DC-DC converter Inductor current-DClink Voltage model is proposed for the DC microgrid. For the controller design in z-domain, the K-factor method is by considering nature of the digital controller. The control performance has been verified with simulation and hardware experiments. Lastly 10kW DC microgrid using RFB test result is shown.

A Study on Variable Speed Generation System with Energy Saving Function

This paper presents development of variable speed generation (VSG) system with energy saving function. The rubber tyred gantry crane (RTGC) requires the power from diesel-engine. Significant fuel savings by reducing the engine speed can be achieved, because all of operation modes except hoisting are required lower power than rated value of engine. When low speed operation output voltage of generator is decrease until acceptable range of motor driver inverters and auxiliary load supplier. According to power demand engine speed is varying from 20 to 60Hz, and voltage is varying between 210Vac and 480Vac. When idle mode or low power operation dc/dc converter operates by constant output voltage control and inverters dc site voltage is compensated by it. This paper proposed 3-phase interleaved boost converter which has the same structure as the commercially available 3-phase inverter and current sharing capability. 400kW interleaved converter is designed and a performance of converter is evaluated through several experiments with a RTGC system. Energy saving VSG system can cut down fuel consumption by 36% and 21.3% at idle and unidirectional load operations.

A new hybrid distribution system interconnected with PV array

Nowadays, due to the increase of the digital product which can be operated in dc voltage, the use of dc power has increased inside the electric appliances. As the appliances has been equipped with ac/dc converter to supply the driving voltage of dc voltage by ac/dc converter, there could occur the problems such as poor power factor, harmonic increase of the input current and the conversion loss. The hybrid distribution (HBD) system proposed in this study indicates the total system which is supplied to the all AC and DC loads at home by the renewable energy of PV system together with AC commercial source from the utility. In this paper is verified the operation principle and the feasibility of the designed HBD system. The twin systems are set up for the comparison of the conventional AC system and the proposed HBD system linked under the same conditions. Particularly the distribution efficiency, power factor and harmonic characteristics are investigated.

Switch Paralleling Characteristic Analysis for FB Converter in 1[kW] Fuel-Cell System

Fuel cell system which can solve the environmental problem is receiving attention. To use utility power necessary power conversion system from low voltage that is generated by fuel cell system. because fuel cell has special characteristic of low voltage high current. To improve PCS`s efficiency the paralleling method is used. Available the method could reduce the switching loss. But the existing research could not be found optimal result and accompanying several effects. In this study analysis several effects causing the parallel method. The effects have been demonstrated through simulations and experiments.