Dong-Hyun Shin

Experimental study on the effects of pre-heating a battery in a low-temperature environment

The performance of a plug-in hybrid electric vehicle (PHEV) or an electric vehicle (EV) is closely related to the performance of its high-voltage battery pack. This is why, among the various means of maintaining a batterys peak performance, the importance of thermal management is emphasized. Since the early stages of the development of Li-ion batteries, much emphasis has been placed on battery cooling in order to secure stability, while less attention has been given to battery heating. However, in a low-temperature environment, using a battery without heating it severely undermines the batterys performance and life expectancy. A PHEV or an EV operates with energy that is stored by charging the battery, which can then be heated by an external source in a low-temperature environment prior to driving. In this study, a battery HILS and an environment simulation system are used to verify that pre-heating a battery in a low-temperature environment, using an external source, such as a charging stand, improves the batterys performance as compared to circumstances in which this is neglected.

Analytical study on low-frequency ripple effect of battery charging

With the recent interest in environment-friendly vehicles such as electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs), various topologies are being proposed for the on-board charger (OBC) required to charge the lithium battery that serves as the energy storage system. If a specific topology is selected and used, the output current of the charger is bound to contain low-frequency ripple that is twice the input power supply frequency. In this study, to analyze the effects of the low-frequency ripple on the lithium battery, a number of charging/discharging cycles are performed to apply low-frequency ripple current and constant current to PHEV lithium battery cells with similar properties. In addition, we conducted capacity test for each specific cycle to compare their performances to analyze the effects of OBCs low-frequency ripple on the battery.

Dynamic SOC Compensation of an Ultracapacitor Module for a Hybrid Energy Storage System

The ultracapacitor module has recently been recast for use in hybrid energy storage systems (HESSs). As a result, accurate state-of-charge (SOC) estimation for an ultracapacitor module is as important as that of primary sources in order to be utilized efficiently in an energy storage system (ESS). However, while SOC estimation via the open-circuit voltage (OCV) method is generally used due to its linear characteristics compared with other ESSs, this method results in many errors in cases of highcurrent charging/discharging within a short time period. Accordingly, this paper introduces a dynamic SOC estimation algorithm that is capable of SOC compensation of an ultracapacitor module even when there is a current input and output. A cycle profile that simulates the operating conditions of a mild-HEV was applied to a vehicle simulator to verify the effectiveness of the proposed algorithm.

The Dynamic Control of Hybrid Energy Storage Sysem for Mild HEV

To improve the cycle life and efficiency of an energy storage system for HEV, a dynamic control system consisted of a switch between battery and ultracapacitor module and a controller is proposed, which is appropriate for mild hybrid vehicle with 42 V power net. The switch can be controlled based on the status of the battery and the ultracapacitor module, and a control algorithm that could largely decrease the number of high charging current peak is also implemented. Therefore the cycle life of the battery can be improved such that it is suitable for a mild hybrid vehicle with frequent engine start-stop and regenerative-braking. Also, by maximizing the use of the ultracapacitor, the system efficiency during high current charging and discharging operation is improved. Finally, this system has the effects that improves the efficiency of energy storage system and reduces the fuel consumption of a vehicle. To verify the validity of the proposed system, this paper presented cycles test results of different energy storage systems: a simple VRLA battery, hybrid energy pack (HEP, a VRLA battery in parallel with Ultracapacitor) and a HEP with a switch that controlled by energy management system (EMS). From the experimental result, it was proved the effectiveness of the algorithm.

A study on the dynamic SOC compensation of an ultracapacitor module for the hybrid energy storage system

There have been a number of methods proposed for accurate state of charge (SOC) estimation of a battery as an important role of the battery management System (BMS). However, adequate test data of batteries and BMS development costs must be taken into consideration before application in actual vehicles. In addition, different algorithms need to be adopted according to the type of energy storage device and system configuration. For a mild-HEV hybrid energy storage device that uses the ultracapacitor module and the VRLA battery, the small capacitance of ultracapacitor module makes accurate SOC difficult. Accordingly, this paper introduces a dynamic SOC estimation algorithm capable of SOC compensation of the ultracapacitor module even when there is current input and output. A cycle profile that simulates the operating conditions of a mild-HEV was applied to a vehicle simulator to verify the effectiveness of the proposed algorithm based on testing.

Modeling of Lithium Battery Cells for Plug-In Hybrid Vehicles

Online simulations are utilized to reduce time and cost in the development and performance optimization of plug-in hybrid electric vehicle (PHEV) and electric vehicles (EV) systems. One of the most important factors in an online simulation is the accuracy of the model. In particular, a model of a battery should accurately reflect the properties of an actual battery. However, precise dynamic modeling of high-capacity battery systems, which significantly affects the performance of a PHEV, is difficult because of its nonlinear electrochemical characteristics. In this study, a dynamic model of a high-capacity battery cell for a PHEV is developed through the extraction of the equivalent impedance parameters using electrochemical impedance spectroscopy (EIS). Based on the extracted parameters, a battery cell model is implemented using MATLAB/Simulink, and charging/discharging profiles are executed for comparative verification. Based on the obtained results, the model is optimized for a high-capacity battery cell for a PHEV. The simulation results show good agreement with the experimental results, thereby validating the developed model and verifying its accuracy.

Modeling of the Lithium Battery Cell for Plug-In Hybrid Electric Vehicle Using Electrochemical Impedance Spectroscopy

Online simulations are utilized to reduce time and cost in developing and optimizing the performance of plug-in hybrid electric vehicle (PHEV) and electric vehicles (EV) systems. One of the most important factors in an online simulation is the accuracy of the model. In particular, a model of a battery should accurately reflect the properties of the actual battery. However, precise dynamic modelling of a high-capacity battery system, which significantly affects the performance of a PHEV, is difficult because of its nonlinear electrochemical characteristics. In this study, a dynamic model of a high-capacity battery cell for a PHEV is developed by the extraction of the equivalent impedance parameters using electrochemical impedance spectroscopy (EIS). Based on the extracted parameters, a battery cell model is implemented using MATLAB/Simulink, and charging/discharging profiles are executed for comparative verification.

A local-dimming LED BLU driving circuit for a 42-inch LCD TV

This paper presents an LED BLU driving circuit with a local-dimming structure. The efficiency of the proposed LED driver has been improved by parallel driving 8 serial-connected LED arrays. It employed the soft-switching boost converter topology to reduce the switching power loss of the hard switching boost converter. The soft-switching converter reveals superior ripple and efficiency. A smaller inductance can be used for the soft-switching converter contrasting to the hard-switching one and studied on an over-voltage protection circuit of the output of the driver at the no load condition.

Extent of linkage disequilibrium and effective population size of Korean Yorkshire swine

Objective We aimed to characterize linkage disequilibrium (LD) and effective population size (Ne) in a Korean Yorkshire population using genomic data from thousands of individuals. Methods We genotyped 2,470 Yorkshire individuals from four major Grand-Grand-Parent farms in Korea using the Illumina PorcineSNP60 version2 BeadChip, which covers >61,565 single nucleotide polymorphisms (SNPs) located across all chromosomes and mitochondria. We estimated the expected LD and inferred current Ne as well as ancestral Ne. Results We identified 61,565 SNP from autosomes, mitochondria, and sex chromosomes and characterized the LD of the Yorkshire population, which was relatively high between closely linked markers (>0.55 at 50 kb) and declined with increasing genetic distance. The current Ne of this Korean Yorkshire population was 122.87 (106.90; 138.84), while the historical Ne of Yorkshire pigs suggests that the ancestor Ne has decreased by 99.6% over the last 10,000 generations. Conclusion To maintain genetic diversity of a domesticated animal population, we must carefully consider appropriate breed management methods to avoid inbreeding. Although attenuated selection can affect short-term genetic gain, it is essential for maintaining the long-term genetic variability of the Korean Yorkshire population. Continuous and long-term monitoring would also be needed to maintain the pig population to avoid an unintended reduction of Ne. The best way to preserve a sustainable population is to maintain a sufficient Ne.

Effects of exercise on myokine gene expression in horse skeletal muscles

Objective To examine the regulatory effects of exercise on myokine expression in horse skeletal muscle cells, we compared the expression of several myokine genes (interleukin 6 [IL-6], IL-8, chemokine [C-X-C motif] ligand 2 [CXCL2], and chemokine [C-C motif] ligand 4 [CCL4]) after a single bout of exercise in horses. Furthermore, to establish in vitro systems for the validation of exercise effects, we cultured horse skeletal muscle cells and confirmed the expression of these genes after treatment with hydrogen peroxide. Methods The mRNA expression of IL-6, IL-8, CXCL2, and CCL4 after exercise in skeletal muscle tissue was confirmed using quantitative-reverse transcriptase polymerase chain reactions (qRT-PCR). We then extracted horse muscle cells from the skeletal muscle tissue of a neonatal Thoroughbred. Myokine expression after hydrogen peroxide treatments was confirmed using qRT-PCR in horse skeletal muscle cells. Results IL-6, IL-8, CXCL2, and CCL4 expression in Thoroughbred and Jeju horse skeletal muscles significantly increased after exercise. We stably maintained horse skeletal muscle cells in culture and confirmed the expression of the myogenic marker, myoblast determination protein (MyoD). Moreover, myokine expression was validated using hydrogen peroxide (H2O2)-treated horse skeletal muscle cells. The patterns of myokine expression in muscle cells were found to be similar to those observed in skeletal muscle tissue. Conclusion We confirmed that several myokines involved in inflammation were induced by exercise in horse skeletal muscle tissue. In addition, we successfully cultured horse skeletal muscle cells and established an in vitro system to validate associated gene expression and function. This study will provide a valuable system for studying the function of exercise-related genes in the future.