• Journal of Power Electronics
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• v.15 no.3
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• pp.849-859
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• 2015

This paper proposes a novel compound-type hybrid energy storage system (HESS) that inherits the unique advantages of both battery/supercapacitor (SC) and the SC/battery HESSs for electric vehicles (EVs). Eight operation modes are designed to match this system. A mode control strategy is developed for this HESS on the basis of these modes, and five classes of operation modes are established to simplify this strategy. The mode control strategy focuses on high operating efficiency and high power output. Furthermore, the compound-type HESS is designed such that the SC is the main priority in braking energy absorption. Thus, this HESS can operate efficiently and extend battery life. Simulation results also show that the compound-type HESS can not only supply adequate power to the motor inverter but can also determine suitable operation modes in corresponding conditions. Experimental results demonstrate that this HESS can extend battery life as well. The overall efficiency of the compound-type HESS is higher than those of the battery/SC and the SC/battery HESSs.

• International Journal of Internet, Broadcasting and Communication
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• v.9 no.2
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• pp.1-10
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• 2017

The high costs of electric vehicle supply equipment (EVSE) and installation are currently a stumbling block to the proliferation of electric vehicles (EVs). The cost-effective solutions are needed to support the expansion of charging infrastructure. In this paper, we develope EV charging system based on the big data analysis of the power consumption patterns. The developed EV charging system is consisted of the smart EV outlet, gateways, powergates, the big data management system, and mobile applications. The smart EV outlet is designed to low costs of equipment and installation by replacing the existing 220V outlet. We can connect the smart EV outlet to household appliances. Z-wave technology is used in the smart EV outlet to provide the EV power usage to users using Apps. The smart EV outlet provides 220V EV charging and therefore, we can restore vehicle driving range during overnight and work hours.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.138-147
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• 1998

This paper describes design and implementation results of a fuzzy logic speed controller of EV(Electric vehicle)'s induction motor for the purpose of realizing comfortable driving. The fuzzy controller is suitable for speed control of EV since that without detailed knowledge about the induction motor, it is easier to design a well-performing speed control system with good stability. PWM wave for driving the induction motor is generated by space vector modulation method and all the control algorithms are realized digitally. The results of experiment show excellence of the proposed system and that the proposed system is appropriate to control the speed of induction motor for commercial EVs.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.1
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• pp.119-123
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• 2012

In traditional vehicles, a great amount of energy is dissipated by braking. In electric vehicles (EVs), however, electric motors can be controlled to operate as generators to convert kinetic and potential energy of vehicles into electrical energy and store it in batteries. In this paper, the relationship between regenerative braking factor and battery final SOC is derived and the final SOC from the relationship is compared to that from simulation. Two types of braking algorithms are introduced and applied to an EV, and the final SOC derived from simulation is compared to that derived from the relationship.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2247-2255
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• 2017

Because the on-board charger (OBC) is installed in electric vehicles (EVs), high power density is regarded as a key technology. Among components of the OBC, inductors occupy more than 30% of the total volume. Thus, it is important to reduce the volume and the weight of inductors while maintaining thermal stability. Discontinuous conduction mode (DCM) can satisfy these requirements; however, only a few studies have adopted the DCM operation for OBCs because of the large inductor current ripple. In this paper, a design process is proposed for application of the DCM operation to OBCs. In order to analyze the inductor losses accurately, a numerical formula for the inductor current ripple is deduced based on a detailed analysis. Two inductors are fabricated using several ferrite cores and powder cores taking into consideration the inductor size, inductor losses, and temperature rise. In order to verify the analysis and design process, experimental results are presented that show that the designed inductors satisfy the requirements of the OBCs.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.2
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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 Electrical Engineering and Technology
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• v.8 no.6
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• pp.1269-1275
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• 2013

Recently, many studies have suggested that an electric vehicle (EV) is one of the means for increasing the reliability of power systems in new energy environments. EVs can make a contribution to improving reliability by providing frequency regulation in power systems in which the Vehicle-to-Grid (V2G) technology has been implemented and, if economically viable, can be helpful in increasing power system reliability. This paper presents a stochastic method for optimal coordination of charging and frequency regulation decisions for an EV aggregator using the Least Square Monte-Carlo (LSMC) with modeling of electricity price uncertainty. The LSMC can be used to assess the value of options based on electricity price uncertainty in order to simultaneously optimize the scheduling of EV charging and regulation service for the EV aggregator. The results of a numerical example show that the proposed method can significantly improve the expected profits of an EV aggregator.

• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1156-1163
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• 2008

We performed RT-nested PCR to study the distribution of human enteric viruses in urban rivers in Korea. During 2002-2003, water samples were collected from four rivers in Gyeonggi Province, South Korea. Among 58 samples, 45 (77.6%), 32 (55.2%), 12 (20.7%), 2 (3.4%), 4 (6.9%), and 4 (6.9%) showed positive results with adenoviruses (AdVs), enteroviruses (EVs), reoviruses (ReVs), hepatitis A viruses (HAVs), rotaviruses (RoVs), and sapoviruses (SVs), respectively. According to the binary logistic regression model, the occurrence of each enteric virus, except ReVs and HAVs, was not statistically correlated with the water temperature and levels of fecal coliforms (P<0.05). AdVs were most often detected; only 4 samples (6.9%) were negative for AdVs while positive for other enteric viruses in the studied sites. Our results indicated that monitoring human enteric viruses is necessary to improve microbial quality, and that AdVs detection by PCR can be a useful index for the presence of other enteric viruses in aquatic environments.

• Journal of Energy Engineering
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• v.20 no.2
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• pp.109-122
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• 2011

The production capacity of EV models should be sufficient to achieve the goal of one million EVs by 2015. Large-Format lithium-ion battery are expected to find a prominent role as ideal electrochemical storage systems in traction power train for sustainable vehicles such as all-electric vehicles. This review focuses first on the present status of production lithium-ion battery technology and cooperative relations of between battery and EV makers, then on its near future development.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.5
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• pp.620-625
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• 2013

This paper presents the design of a switched reluctance motor (SRM) for electric air conditioning compressors which are applied to hybrid electric vehicles (EVs). The motor for driving air conditioning compressor which is recently used on EV(electric vehicle) / HEV (hybrid electric vehicle) is PMSM(permanent magnet synchronous motor) or BLDCM(brushless DC motor). However disadvantage of motors that uses permanent magnets are vulnerable to high temperatures because of the demagnetization by the high temperature and the permanent magnet is expensive because of the high price of rare earth materials from China's monopoly. Therefore, in the automotive insustry is interested in the non-rare-earth motors. SRM has many advantages. it's resistant to high temperatures, price is cheaper, because there are no permanent magnets and winding in the rotor. Also it's high relability and efficiency, suitable for high-speed operation because of structure is simple. In this paper, the SRM, non-rare-earth motor, are designed, analyzed and experimented drive to replace an existing electric compressor drive motor.