• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.4
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• pp.277-284
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• 2021

A single and three phase-compatible single-stage EV charger without electrolytic capacitor is proposed in this study. DC battery-charging current is inherently guaranteed in the three-phase grid due to three output currents with a phase shift of 120° between each other. The proposed EV charger can provide a DC battery charging current for the single-phase grid through the integrated active power decoupling circuit without using additional switches. The proposed EV charger ensures ZVS turn-on of all switches with wide grid and battery voltage ranges. The 11 kW prototype of the proposed EV charger demonstrates a peak efficiency of 97.01% and a power density of 5.58 kW/L.

• Proceedings of the KIPE Conference
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• 2012.07a
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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.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.3
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• pp.387-396
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• 2022

Recently, e-Mobility, which is a personal mobility device such as an electric bicycle or an electric scooter, is rapidly emerging. However, since E-Mobility has various voltage systems due to the characteristics of its products, it is essential for companies that operate them to use multiple dedicated chargers. A universal charger capable of charging batteries of various voltage systems with one charger is required to reduce the cost of purchasing and managing multiple dedicated chargers. For this, information on the EOC(End of Charge) is essential. In order to know the EOC, it is necessary to detect the internal impedance of the battery. However, the internal impedance of the battery changes according to various conditions such as SOH(State Of Health), SOC(State Of Charge), and ambient temperature. By observing the change in these parameters, the state of the battery can be diagnosed and the EOC can be predicted. In this paper, we propose an algorithm to analyze the battery's internal impedance and to predict the EOC, in order to acquire information on the EOC of the battery, which is an essential requirement of a universal charger.

• Journal of The Korean Society of Integrative Medicine
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• v.12 no.2
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• pp.167-176
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• 2024

Purpose: This study aimed to verify the effectiveness of suicide prevention education using the "Life Charger" program for older adults. Methods: This study conducted the "Life Charger"suicide prevention education with 95 older adults in the experimental group. Participants were recruited from a senior welfare center and a senior citizen center in D metropolitan city, and their attitudes toward suicide and sense of competence in providing help before and after the education were investigated. While no measures were taken for the control group, their attitudes toward suicide and help-giving competence were surveyed during the same period. Statistics were analyzed using SPSS 23.0, demographic variables of the experimental and control groups were calculated as percentiles, and Chi-square analysis and paired-sample t-test were performed to verify the homogeneity of the experimental and control groups. Results: To verify the effectiveness of the "Life Charger"suicide prevention education, the effectiveness of attitude toward suicide before and after the education was verified. The experimental group showed a significantly higher level (t=-6.34, p<.000). Their competence in providing help was also at a significantly higher level (t=-10.20, p<.000). Upon verifying the effectiveness of the program, the experimental group's attitude toward suicide was found to be significantly higher; however, the control group showed no change in attitude toward suicide and competence in providing help. Conclusion: This study verified that the "Life Charger"suicide prevention education for older adults was effective in increasing attitudes toward suicide and sense of competence in providing help. To increase the effectiveness of suicide prevention education for older adults, follow-up research should determine whether there are any actual changes after the training, and attitudes toward suicide and help-providing competence should be increase d through universal and repetitive education to prevent suicide among older adults.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1074-1076
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• 2000

This Paper reports on an experimental and theoretical work about self exited Half-Bridge inverter for contact less battery chargers. The steady state characteristics of inverter are analysis and the experimental result for 500kHz, universal AC source input have been obtained. These inverter is suitable for the portable appliances with battery chargers such as cellular phone.