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Lithium ion battery equalization circuit based on symmetrical CLLC direct-current converter

A technology of DC converters and lithium-ion batteries, which is applied in battery circuit devices, circuit devices, collectors, etc., can solve the problems of high cost and large circuit volume, and achieve simple control, improved equilibrium efficiency, and reduced switching loss Effect

Pending Publication Date: 2021-04-20
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this equalization circuit needs to add one more winding for transformer degaussing for each battery group, which leads to the disadvantages of large circuit size and high cost.

Method used

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  • Lithium ion battery equalization circuit based on symmetrical CLLC direct-current converter
  • Lithium ion battery equalization circuit based on symmetrical CLLC direct-current converter
  • Lithium ion battery equalization circuit based on symmetrical CLLC direct-current converter

Examples

Experimental program
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Effect test

Embodiment

[0046] figure 1 It is a lithium-ion battery balancing circuit based on a symmetrical CLLC DC converter disclosed in the embodiment of the present invention, including a series battery pack, a full-bridge switch network, a CLLC DC converter, a voltage sampling circuit, a controller, and a switch drive circuit . figure 1 The medium-series battery pack includes n-section lithium-ion battery cells.

[0047] The voltage sampling circuit collects the voltages of n battery cells of the battery pack connected in series;

[0048] The controller receives n battery cell voltages from the voltage sampling circuit, judges the battery cell with the highest voltage according to the n battery cell voltages, and outputs a switch signal;

[0049] The switch drive circuit receives the switch signal from the controller, amplifies the switch signal, and outputs it to the full-bridge switch network.

[0050] figure 2 It is a balance circuit suitable for 4 series lithium-ion batteries based on ...

Embodiment 2

[0066] Figure 7 It is a balancing circuit suitable for 4 series lithium-ion batteries based on a symmetrical CLLC DC converter in the embodiment of the present invention, including a series connection of 4 battery cells to obtain a series battery pack, a full-bridge switch network, and a CLLC DC conversion devices, controllers and switch drive circuits. Wherein, the connection mode of the series battery pack, the full-bridge switch network and the CLLC DC converter is the same as that of the first embodiment.

[0067] The controller outputs the switch signal;

[0068] The switch drive circuit receives the switch signal from the controller, amplifies the switch signal, and outputs it to the full-bridge switch network.

[0069] Assuming battery voltage VB 1 =4.0V, VB 2 =3.97V, VB 3 =3.93V, VB 4 =3.9V, which is the average voltage of the battery cell. Since there is no voltage sampling circuit, control method two is adopted. The controller outputs the first switch signal...

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Abstract

The invention discloses a lithium ion battery equalization circuit based on a symmetrical CLLC direct-current converter. The equalization circuit comprises a series battery pack, a full-bridge switching network, the CLLC direct-current converter, a voltage sampling circuit, a controller and a switch driving circuit. Static and dynamic equalization of the battery pack is realized through the symmetrical CLLC direct-current converters, the equalization speed is high, the control is simple, and the available capacity of the battery pack is effectively improved. Zero-voltage switching is achieved through the follow current effect of the body diodes connected with the N-channel MOSFETs in parallel, the switching loss is greatly reduced, the switching frequency can be improved, and the circuit size is reduced. The full-bridge switch network control method in the equalization circuit not only can realize static equalization of the series battery pack, but also can realize dynamic equalization of the series battery pack, and is suitable for more equalization scenes. In addition, when the number of batteries connected in series is large, the number of voltage sampling circuits can be reduced, and the circuit cost is low.

Description

technical field [0001] The invention relates to the technical field of equalization of lithium-ion battery packs, in particular to a lithium-ion battery equalization circuit based on a symmetrical CLLC DC converter. Background technique [0002] Lithium-ion batteries have the advantages of high energy density, high cycle efficiency, low self-discharge rate, and no memory effect, and are widely used in new energy vehicles and energy storage power stations. However, due to the limited voltage and capacity of single batteries, in order to meet the demand of load power and voltage, whether it is the battery pack of electric vehicles or the energy storage system for new energy power generation, a large number of single batteries need to be connected in series and parallel. Due to certain errors in the production process, combined with various factors such as the use period, the inconsistency of lithium-ion battery packs will increase over time after multiple charge and discharge ...

Claims

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Application Information

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IPC IPC(8): H02J7/00H02M1/00
CPCY02B70/10
Inventor 康龙云林鸿业罗璇卢楚生于玮
Owner SOUTH CHINA UNIV OF TECH
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