Adjacent Cell-to-Cell equalization circuit and control method based on three-resonance state lc conversion

A technology of equalization circuit and series resonant circuit, which is applied in the direction of charge equalization circuit, circuit device, battery circuit device, etc., can solve problems such as difference, battery voltage or SOC extremely unbalanced, and low equalization efficiency, so as to achieve wide practicability and reduce Small size, the effect of improving the equalization efficiency

Active Publication Date: 2018-01-09
SHANDONG UNIV
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  • Claims
  • Application Information

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Problems solved by technology

Unfortunately, series-connected lithium battery packs bring a more serious problem: small differences in internal resistance or capacity between battery cells may lead to extreme imbalances in voltage or SOC between battery cells
However, the main problem of this invention is that the equalization efficiency is inversely proportional to the voltage difference between battery cells, the greater the voltage difference, the lower the equalization efficiency

Method used

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  • Adjacent Cell-to-Cell equalization circuit and control method based on three-resonance state lc conversion
  • Adjacent Cell-to-Cell equalization circuit and control method based on three-resonance state lc conversion
  • Adjacent Cell-to-Cell equalization circuit and control method based on three-resonance state lc conversion

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Embodiment 1

[0060] As shown in Figure 1, the microcontroller of the equalization circuit uses a digital signal processing chip DSP (TMS320F28335), which has high-precision AD sampling and PWM output; The voltage of the battery; the battery module is a lithium iron phosphate power battery with a capacity of 6.2Ah. As shown in Figure 1(a), it is the overall model diagram of the three-resonance state LC conversion module applied to the battery pack. Every two adjacent battery cells share a three-resonance state LC conversion module. For an N-cell battery cell The battery packs connected in series share (N-1) three-resonance state LC conversion modules.

[0061] As shown in Figure 1(b), the three-resonance state LC conversion module is applied to two adjacent battery cells B 0 and B 1 . The three-resonance state LC conversion module consists of four MOS tubes Q 0 -Q 3 Series branch, LC series resonant circuit and a MOS tube branch Q 4 composition. Among them, MOS tube Q 0 The drain of...

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Abstract

The invention discloses an Adjacent Cell-to-Cell equalization circuit and a control method based on LC conversion in a three-resonance state. The equalization circuit mainly includes a microcontroller, N battery cells and N-1 LC conversion modules in a three-resonance state. Each adjacent two battery cells share a three-resonance state LC conversion module; the microcontroller sends three PWM signals with a phase difference of 120 degrees and a duty cycle of 33.3% to control the three-resonance state LC resonance conversion to work alternately during charging , discharge and release states. Due to the introduction of the release state, the present invention further discharges and reverse charges the capacitor C, which increases the balance current on the one hand; on the other hand, it also obtains the flow of energy between battery cells with small voltage difference or even zero voltage difference. The equalization of zero voltage difference between battery cells provides the conditions.

Description

technical field [0001] The invention relates to an Adjacent Cell-to-Cell equalization circuit and a control method based on LC transformation in a three-resonant state. Background technique [0002] Lithium-ion power batteries have the advantages of high energy density, low self-discharge rate and no memory effect, and are the main power batteries for electric vehicles and hybrid electric vehicles. However, due to the low voltage of the battery cells, in order to obtain a higher voltage level, they are often used in series in practical applications. Unfortunately, series-connected lithium battery packs bring a more serious problem: small differences in internal resistance or capacity between battery cells may lead to extreme imbalances in voltage or SOC between battery cells. In addition, after several charge-discharge cycles, this imbalance will become more and more serious, which greatly reduces the usable capacity and cycle life of the battery pack. Even, safety acciden...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J7/00
CPCH02J7/0016
Inventor 张承慧商云龙李泽元周忠凯段彬
Owner SHANDONG UNIV
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