• Title/Summary/Keyword: Balancing current

Search Result 4, Processing Time 0.061 seconds

Transformer Design Methodology to Improve Transfer Efficiency of Balancing Current in Active Cell Balancing Circuit using Multi-Winding Transformer (다중권선 변압기를 이용한 능동형 셀 밸런싱 회로에서 밸런싱 전류 전달 효율을 높이기 위한 변압기 설계 방안)

  • Lee, Sang-Jung;Kim, Myoung-Ho;Baek, Ju-Won;Jung, Jee-Hoon
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.23 no.4
    • /
    • pp.247-255
    • /
    • 2018
  • This paper proposes a transformer design of a direct cell-to-cell active cell balancing circuit with a multi-winding transformer for battery management system (BMS) applications. The coupling coefficient of the multi-winding transformer and the output capacitance of MOSFETs significantly affect the balancing current transfer efficiency of the cell balancing operation. During the operation, the multi-winding transformer stores the energy charged in a specific source cell and subsequently transfers this energy to the target cell. However, the leakage inductance of the multi-winding transformer and the output capacitance of the MOSFET induce an abnormal energy transfer to the non-target cells, thereby degrading the transfer efficiency of the balancing current in each cell balancing operation. The impacts of the balancing current transfer efficiency deterioration are analyzed and a transformer design methodology that considers the coupling coefficient is proposed to enhance the transfer efficiency of the balancing current. The efficiency improvements resulting from the selection of an appropriate coupling coefficient are verified by conducting a simulation and experiment with a 1 W prototype cell balancing circuit.

A Novel Cell Balancing Circuit for Fast Charge Equalization (빠른 전하 균일화를 위한 새로운 구조의 셀 밸런싱 회로)

  • Park, Dong-Jin;Choi, See-Young;Kim, Yong-Wook;Kim, Rae-Young
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.20 no.2
    • /
    • pp.160-166
    • /
    • 2015
  • This study proposes an improved cell balancing circuit for fast equalization among lithium-ion (Li-ion) batteries. A simple voltage sensorless charge balancing circuit has been proposed in the past. This cell balancing circuit automatically transfers energy from high-to low-voltage battery cells. However, the circuit requires a switch with low on-resistance because the balancing speed is limited by the on-resistance of the switch. Balancing speed decreases as the voltage difference among the battery cells decrease. In this study, the balancing speed of the cell balancing circuit is enhanced by using the auxiliary circuit, which boosts the balancing current. The charging current is determined by the nominal battery cell voltage and thus, the balancing speed is almost constant despite the very small voltage differences among the batteries. Simulation results are provided to verify the validity of the proposed cell balancing circuit.

A New LED Current Balancing Scheme Using Double-Step-Down DC-DC Converter (이중강압 DC-DC 컨버터를 이용한 새로운 LED 전류 밸런싱 기법)

  • Kim, Kisu;Do, Duc Tuan;Kim, Heung-Geun;Cha, Honnyong
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.66 no.10
    • /
    • pp.1474-1480
    • /
    • 2017
  • This paper presents a new LED current balancing scheme using double-step-down dc-dc converter. With the proposed structure, the two channel LED currents are automatically balanced without using any dedicated control or auxiliary circuit. In addition, switching loss of the switching devices in the proposed LED driver is lower than that of the conventional buck LED driver. To verify the operation of the proposed LED driver, a hardware prototype is built and tested with different number of LED.

Implementation of Battery Management System for Li-ion Battery Considering Self-energy Balancing (셀프에너지 밸런싱을 고려한 리튬이온전지의 Battery Management System 구현)

  • Kim, Ji-Myung;Lee, Hu-Dong;Tae, Dong-Hyun;Ferreira, Marito;Park, Ji-Hyun;Rho, Dae-Seok
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.21 no.3
    • /
    • pp.585-593
    • /
    • 2020
  • Until now, 29 fire accidents have occurred; 22 of them were caused by the interconnection of renewable energy sources that occurred during the rest period after the lithium-ion battery had been fully charged regardless of the seasons. The fire accidents of ESS were attributed to thermal runaway due to the overcharging of a few cells with the phenomenon of self-energy balancing, which is unintentional current flow from cells with a high SOC to the low cells if the SOC condition of each cell connected in parallel is different. Therefore, this paper proposes a novel configuration and operation algorithm of the BMS to prevent the self-energy balancing of ESS and presents a hybrid SOC estimation algorithm. From the test results of the self-energy balancing phenomenon between aging and normal cells based on the proposed algorithm and BMS, it was confirmed the possibility of self-energy balancing, which is unintentional current flow from cells with a high SOC to cells with a low SOC. In addition, the proposed configuration of the BMS is useful and practical to improve the safety of lithium-ion batteries because the BMS can reliably disconnect a parallel connection of the cells if the self-energy balancing current becomes excessively high.