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Active equalization method for lithium ion battery pack in charging state

A lithium battery pack and charging equalization technology, which is applied in secondary battery charging/discharging, battery circuit devices, electric vehicles, etc., can solve the problems of increasing system complexity, reducing power transfer efficiency, and low transfer efficiency, achieving high efficiency , large depth, high power effect

Inactive Publication Date: 2010-04-07
北京北方专用车新技术发展有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that it can only transfer power between adjacent lithium batteries. For non-adjacent lithium batteries, multiple power transfers are required to achieve the purpose of balance, which greatly reduces the power transfer efficiency.
And since a single equalization module can only balance two adjacent batteries, then for a multi-string lithium battery pack, multiple equalization modules are required, which greatly increases the complexity of the system
Capacitive transfer method Since the voltage difference in the lithium battery pack is between a few millivolts and tens of milliseconds, the amount of electricity transferred in a single transfer is very small, so the transfer efficiency of this method is also very low.

Method used

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  • Active equalization method for lithium ion battery pack in charging state
  • Active equalization method for lithium ion battery pack in charging state
  • Active equalization method for lithium ion battery pack in charging state

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach 1

[0035] Embodiment 1: Equalization during charging of 6-series lithium battery pack

[0036] Components and parameter settings: 1) The discharge current of the capacitor is 2A, the end-of-discharge voltage is 2V, and the end-of-charge voltage is the value of the battery voltage minus 0.3. Calculated according to formula (1), when the battery voltage is 3.8V, the capacitor charging termination voltage is 3.5V, at this time the capacitor charging time is 7.2s, and the average charging current is 4.1A. 2) For the farad capacitor, choose two 20F series farad capacitor modules, and the withstand voltage is about 5.4V. 3) Inductor According to Formula 4 and Formula 5, select an inductor with an inductance of 330μH and a current above 4.5A that will not saturate. 4) Boost control frequency is set to 2kHz. 5) The capacitor charging control MOS tube and the Boost control MOS tube are P-type MOS tubes, the model is IRML6401.

[0037] The capacitor capacity is 8Ah, the charging cut-off...

Embodiment approach 2

[0039] Embodiment 2: Equalization during small current discharge

[0040] Components and parameter settings: 1) The discharge current of the capacitor is 2A, the end-of-discharge voltage is 2V, and the end-of-charge voltage is the value of the battery voltage minus 0.3. Calculated according to formula (1), when the battery voltage is 3.8V, the capacitor charging termination voltage is 3.5V, at this time the capacitor charging time is 7.2s, and the average charging current is 4.1A. 2) For the farad capacitor, choose two 20F series farad capacitor modules, and the withstand voltage is about 5.4V. 3) Inductor According to Formula 4 and Formula 5, select an inductor with an inductance of 330μH and a current above 4.5A that will not saturate. 4) Boost control frequency is set to 2kHz. 5) The capacitor charging control MOS tube and the Boost control MOS tube are P-type MOS tubes, the model is IRML6401.

[0041] The capacitor capacity is 8Ah, and the initial voltage of the battery...

Embodiment approach 3

[0043] Embodiment 3: Equilibrium during standing

[0044] Components and parameter settings: 1) The discharge current of the capacitor is 2A, the end-of-discharge voltage is 2V, and the end-of-charge voltage is the value of the battery voltage minus 0.3. Calculated according to formula (1), when the battery voltage is 3.8V, the capacitor charging termination voltage is 3.5V, at this time the capacitor charging time is 7.2s, and the average charging current is 4.1A. 2) For the farad capacitor, choose two 20F series farad capacitor modules, and the withstand voltage is about 5.4V. 3) Inductor According to Formula 4 and Formula 5, select an inductor with an inductance of 330μH and a current above 4.5A that will not saturate. 4) Boost control frequency is set to 2kHz. 5) The capacitor charging control MOS tube and the Boost control MOS tube are P-type MOS tubes, the model is IRML6401.

[0045] The capacitor capacity is 8Ah, and the initial voltage of the battery pack is 21.892V...

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Abstract

The invention discloses an active equalization technique of a lithium battery pack. Based on booster technology and a super capacitor, the technique can be used for voltage equalization of large capacity series connected lithium battery packs in charging state. The conventional active equalization technique has the problems of low electric quantity transmission efficiency, complex controlling and the like. By combining an electric quantity transmission technique of inductor and capacitance, the active equalization technique of the invention can perform electricity quantity transmission of any two batteries in the lithium ion battery pack to achieve the aim of voltage equalization of the lithium ion battery pack, and the comprehensive efficiency can reach about 84 percent. The conventional active equalization technique is characterized by flexible specific control, high efficiency of electricity quantity transmission and the like.

Description

technical field [0001] The invention relates to a power balance method of a series lithium ion battery pack, which can be used for voltage balance in a charging state of a large capacity power series lithium ion battery pack. Background technique [0002] Lithium-ion battery [hereinafter referred to as lithium battery] is a battery with high energy density, high working voltage, no memory effect, long cycle life, no pollution, light weight, and small self-discharge. It is currently widely used in various industries. Since the working voltage of lithium batteries is generally around 2.5~4.2V (lithium batteries of different materials are different), in practical applications, several, dozens or even hundreds of single lithium batteries need to be connected in series to increase the working voltage . However, due to the limitations of the lithium battery production process, there are inconsistencies in the capacity, voltage, internal resistance and self-discharge rate between ...

Claims

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Application Information

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IPC IPC(8): H01M10/44H02J7/00
CPCY02E60/12Y02E60/10
Inventor 雷晶晶张金顶龙泽宋克岭胡松
Owner 北京北方专用车新技术发展有限公司
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