• 전력전자학회논문지
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• 제20권2호
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• pp.182-192
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• 2015

This study develops a digital control scheme with power factor correction for a front-end converter in an electric vehicle battery charger. The front-end converter acts as the boost-type switching-mode rectifier. The converter assumes the two roles of the battery charger, which include power factor control and robust charging performance. The proposed control scheme consists of a charging control algorithm and a grid current control algorithm. The scheme aims to obtain unity input power factor and robust performance. Based on the linear average model of the converter, a constant-current constant-voltage charging control algorithm that passes through only one proportional-integral controller and a current feed-forward path is proposed. In the current control algorithm, we utilized a second band pass filter, a single-phase phase-locked loop technique, and a duty-ratio feed-forward term to control the grid current to be in phase with the grid voltage and achieve pure sinusoidal waveform. Simulations and experiments were conducted to verify the effectiveness of the proposed control scheme, both simulations and experiments.

• Journal of Power Electronics
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• 제14권5호
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• pp.1038-1046
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• 2014

Lithium-ion batteries are widely used in hybrid and pure electric vehicles. State-of-charge (SOC) estimation is a fundamental issue in vehicle power train control and battery management systems. This study proposes a novel model-based SOC estimation method that applies closed-loop state observer theory and a comprehensive battery model. The state-space model of lithium-ion battery is developed based on a three-order resistor-capacitor equivalent circuit model. The least square algorithm is used to identify model parameters. A multi-state closed-loop state observer is designed to predict the open-circuit voltage (OCV) of a battery based on the battery state-space model. Battery SOC can then be estimated based on the corresponding relationship between battery OCV and SOC. Finally, practical driving tests that use two types of typical driving cycle are performed to verify the proposed SOC estimation method. Test results prove that the proposed estimation method is reasonably accurate and exhibits accuracy in estimating SOC within 2% under different driving cycles.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.232-233
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• 2012

This paper presents an effective control scheme for an electric vehicle battery charger where a symmetrical bridgeless power factor-corrected converter and a buck converter are cascaded. Both converters have been popular in industries because of their high efficiency, low cost, and compact size, hence combining these converters makes the overall battery charging system strongly efficient. Moreover, this charger topology can operate at universal input voltage and attain a desired battery current and voltage without ripple. In order to achieve a unity input power factor and zero input current harmonic distortion, the proposed control scheme adopts duty ratio feed-forward control technique in both current and voltage control loop. Additionally, in the current loop, its reference is created by a phase-locked loop (PLL) block, leading to a pure sinusoidal input current although the input voltage waveform is being distorted. The feasibility and practical value of the proposed approach are verified by simulation and experiment with an 110V/60Hz ac line input and 1.5kW-72V dc output of the battery charging system.

• 한국수소및신에너지학회논문집
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• 제21권3호
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• pp.149-157
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• 2010

The electromagnetic characteristics of FCEVs (fuel cell electric vehicles) are much different from the existing combustion engine cars as well as hybrid, plug-in-hybrid, and pure electric vehicles due to the high voltage/current generated by a fuel cell stack which uses a compressed hydrogen gas reacted with oxygen. To operate fuel cell stack efficiently, BOP (Balance of Plant) is essential. BOP systems are used many not only for motors in water pump, air blower, and hydrogen recycling pump but also inverters for these motors. Since these systems or components are connected by high voltage cables, EMC (Electromagnetic compatibility) analysis for high voltage/current cable is the most important element to prevent the possible electric functional safety errors. In this paper, electromagnetic fields of high current/voltage cable for FCEVs is studied. From numerical analysis results, time harmonic magnetic field strength of high current/voltage cable have difference of 20～28 dB according to phase. EMI result considered ground effect of FECV at 10 m shows difference of 14.5 dB at 30 MHz and 2.8 dB at 230 MHz compared with general cable.

• 대한조선학회논문집
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• 제61권1호
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• pp.19-28
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• 2024

Environmental regulations are becoming more stringent in response to climate change, especially concerning marine pollution caused by ship emissions. Large ships are adjusting by integrating technologies to reduce pollutant emissions and transitioning to eco-friendly fuels such as low-sulfur oil and LNG. However, small ships face space constraints for installing LNG propulsion systems and the risk of power depletion with pure electric propulsion. Consequently, there's growing interest in researching hybrid propulsion methods that combine electricity and diesel for smaller vessels. Hybrid propulsion systems utilize diverse energy sources, requiring an effective method for evaluating their efficiency. This study proposes employing Bond graph modeling to comprehensively analyze energy dynamics within hybrid propulsion systems, facilitating better understanding and optimization of their efficiency. Modeling of the ship's energy system using Bond graphs will be able to provide a framework for integrating various energy sources and evaluating their effects.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 학술대회 논문집 전문대학교육위원
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• pp.181-184
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• 2006

In this study, an robust adaptive backstepping controller is proposed for the speed control of separately excited DC motor with uncertainties and disturbances. Armature and field resistance, damping coefficient and load torque are considered as uncertainties and noise generated at applying load torque to motor is also considered. It shows that the backstepping algorithm can be used to solve the problems of nonlinear system very well and robust controller can be designed without the variation of adaptive law. Simulation and experiment results are provided to demonstrate the effectiveness of the proposed controller in the future.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권8호
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• pp.2666-2687
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• 2022

As a new alternative communication scheme in 5G, unmanned aerial vehicle (UAV) is used as a relay in the remote base station (BS) for assistant communication. In order to ameliorate the quality of the backhaul link, a UAV backhaul transmission scheme based on improved Nash equilibrium (NE) strategy is proposed. First, the capacity of air-to-ground (A2G) channel by the link preprocess is maximized. Then, the maximum utility function of each UAV is used as the basis of obtaining NE point according to the backhaul channel and the backhaul congestion. Finally, the improved NE strategy is applied in multiple iterations until maximum utility functions of all the UAVs are reached, and the UAVs which are rejected by air-to-air (A2A) link during the process would participate in the source recovery process to construct a multi-hop backhaul network. Simulation results show that average effective backhaul rate, minimum effective backhaul rate increases by 10%, 28.5% respectively in ideal A2G channel, and 11.8%, 42.3% respectively in fading channel, comparing to pure NE strategy. And the average number of iterations is decreased by 5%.