Single-Magnetic Cell-to-Cell Charge Equalization Converter With Reduced Number of Transformer Windings

Park, Sang‐Hyun; Park, Ki-Bum; Kim, Hyoung-Suk; Moon, Gun-Woo; Youn, Myung-Joong

doi:10.1109/tpel.2011.2178040

Cited by 195 publications

(42 citation statements)

References 28 publications

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“…Based on the main balancing components, active balancing circuits can be divided into three groups: capacitor based balancing circuits [11,[29][30][31][32][33][34][35][36], inductor based balancing circuits [5,8,27,[37][38][39][40][41][42][43][44][45] and transformer based balancing circuits [6,7,25,26,[46][47][48][49][50][51]. Not every active balancing circuit can use SOC as the balancing criterion due to the nature of the balancing components and the topology of the balancing circuits.…”

Section: Current Calculation Of Each Cell For Soc Estimation With Flymentioning

confidence: 99%

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A Novel Active Online State of Charge Based Balancing Approach for Lithium-Ion Battery Packs during Fast Charging Process in Electric Vehicles

et al. 2017

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Non-uniformity of Lithium-ion cells in a battery pack is inevitable and has become the bottleneck to the pack capacity, especially in the fast charging process. Therefore, a balancing approach is essentially required. This paper proposes an active online cell balancing approach in a tfast charging process using the state of charge (SOC) as balancing criterion. The goal of this approach is to complete pack balancing within the limited charging time. An adaptive extended Kalman filter (AEKF) is applied to estimate the pack cell SOC during the charging process to obtain accurate results under modeling errors and measurement noises. To implement the proposed AEKF, only one additional current sensor is required to obtain the current of each cell required for the SOC estimation. An experimental platform is established to verify the effectiveness of the proposed approach. The results show that the proposed balancing approach with the SOC as a balancing criterion can overcome the challenges of non-uniformity and flat voltage plateau and charge more capacity into a LiFePO 4 battery pack than those with the terminal voltage as a balancing criterion in the fast charging process.Keywords: lithium-ion battery pack; the active cell balancing for battery packs; fast charging with balancing; electric vehicles; adaptive extended Kalman filter; pack SOC estimation Highlights:• Adaptive extended Kalman filter (AEKF) is employed to estimate the pack cell state of charge (SOC) in real time, which is used as a balancing criterion to equalize cells in a LiFePO 4 battery pack in the fast charging process.• Only one additional current sensor in the chosen balancing circuit is required to accurately estimate pack cell SOC, leading to low cost implementation.• Balancing in the fast charging process based on online estimated SOC overcomes non-uniformity and allows more pack capacity to be charged. •Experimental platform is established to demonstrate that the performances based on the SOC criterion is better than those based on the terminal voltage criterion in terms of extra charged capacity of 2.07 Ah, equivalent to 13% of the nominal capacity of the chosen battery pack.

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Section: Current Calculation Of Each Cell For Soc Estimation With Flymentioning

confidence: 99%

“…Recently, active cell balancing is widely used in maintenance conditions in which the charging or discharging stops when the balancing operates [5][6][7][8]. In maintenance conditions, there is no strict restriction of balancing time and balancing speed is not critical.…”

Section: Introductionmentioning

confidence: 99%

A Novel Active Online State of Charge Based Balancing Approach for Lithium-Ion Battery Packs during Fast Charging Process in Electric Vehicles

et al. 2017

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“…In active balancing systems, the balancing circuits (BCs) can be divided into three groups on the basis of the main component that transfers charge or energy among the cells in a pack; capacitor-based balancing circuits (CBCs) [4][5][6][7][8], transformer-based balancing circuits (TBCs) [9][10][11][12][13][14][15][16][17], and inductor-based balancing circuits (IBCs) [18][19][20][21][22][23][24][25][26][27][28][29][30][31]. CBCs generally have low implementation costs, but their balancing speed is slow, especially when the voltage differences among the cells in the pack are low.…”

Section: Introductionmentioning

confidence: 99%

A Fast Multi-Switched Inductor Balancing System Based on a Fuzzy Logic Controller for Lithium-Ion Battery Packs in Electric Vehicles

et al. 2017

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Based on a low cost multi-switched inductor balancing circuit (MSIBC), a fuzzy logic (FL) controller is proposed to improve the balancing performances of lithium-ion battery packs instead of an existing proportional-integral (PI) controller. In the proposed FL controller, a cell's open circuit voltages (OCVs) and their differences in the pack are used as the inputs, and the output of the FL controller is the balancing current. The FL controller for the MSIBC has the advantage of maintaining high balancing currents over the existing PI controller in almost the entire balancing process for different lithium battery types. As a result, the proposed FL controller takes a much shorter time to achieve battery pack balancing, and thus more pack capacity can be recovered. This will help to improve the pack performance in electric vehicles and extend the serving time of the battery pack.

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“…A circuit for balancing with one small transformer and N+3 bilateral switches was presented in [20]. A cell-to-cell charge equalization converter using a multi-winding transformer was discussed in [21], which achieved direct cell-to-cell charge transportation by buck-boost and fly-back operation. Though topologies based on transformers have the advantages of high balancing current and efficiency, voltage/current spikes still exist, which will lead to switching losses.…”

Section: Introductionmentioning

confidence: 99%

Battery Equalization by Fly-Back Transformers with Inductance, Capacitance and Diode Absorbing Circuits

Liu

Sun

et al. 2017

Energies

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Battery equalization can increase batteries' life cycle, utilization, and reliability. Compared with battery equalization topologies based on resistance or energy storage components, the topologies based on transformers have the advantages of high balancing current and efficiency. However, the existence of switching losses will reduce the reliability and service life span of the equalization circuit. Aiming at resolving this problem, a new battery equalization topology by fly-back transformer with an absorbing circuit is proposed in this paper. Compared with other transformer-based topologies, it can decrease switching losses because the voltage/current spike is solved by the absorbing circuit which is composed of inductance, capacitance and diode (LCD), and it can also maintain a high balancing current of about 1.8 A and high efficiency of about 89%, while the balancing current and efficiency of other topologies were usually 1.725 A/1.5 A and 80%/80.4%. The working principle of the balancing topology and the process of soft switching are analyzed and calculated in the frequency domain. Due to the addition of the LCD absorbing circuit, soft switching can be realized to reduce the switching losses while the high equalization speed and efficiency are still maintained. The corresponding control strategy of the balancing topology is also proposed and the timely balancing is achieved. The theoretical analysis is verified by simulation and experimental results.

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Single-Magnetic Cell-to-Cell Charge Equalization Converter With Reduced Number of Transformer Windings

Cited by 195 publications

References 28 publications

A Novel Active Online State of Charge Based Balancing Approach for Lithium-Ion Battery Packs during Fast Charging Process in Electric Vehicles

A Novel Active Online State of Charge Based Balancing Approach for Lithium-Ion Battery Packs during Fast Charging Process in Electric Vehicles

A Fast Multi-Switched Inductor Balancing System Based on a Fuzzy Logic Controller for Lithium-Ion Battery Packs in Electric Vehicles

Battery Equalization by Fly-Back Transformers with Inductance, Capacitance and Diode Absorbing Circuits

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