Equilibrium circuit and equilibration method of series battery pack based on lc-l

Abstract

The invention discloses an LC-L bases serial battery pack balance circuit and a balance method. A serial battery pack consists of n single batteries; the balance circuit comprises (2n+2) MOS tubes, (2n+2) diodes and a LC-L energy storage circuit; the LC-L energy storage circuit comprises an inductor L, a capacitor C, a diode VD and a di / dt suppression circuit; the di / dt suppression circuit comprises a buffer inductor Lb, a resistor Rb and a diode VDb. The first characteristic of the balance circuit is that the whole balance circuit only needs one LC-L energy storage circuit for energy transfer, so that the size of the balance circuit can be greatly reduced; the second characteristic of the balance circuit is that expansion is easy, and number of corresponding MOS tubes only needs to increase or reduce while number of the single batteries of the serial battery pack changes; and the third characteristic of the balance circuit is that balance speed is quick, and balance energy in a charging and discharging process can be directly transferred to low-energy single bodies from high-energy single bodies.

Description

technical field [0001] The invention belongs to the technical field of battery equalization, and relates to an LC-L-based equalization circuit and equalization method of series battery packs, which are suitable for battery management systems in new energy vehicles. Background technique [0002] With the rapid economic development, energy crisis and environmental pollution problems are becoming more and more prominent. As a sustainable transportation mode, new energy vehicles will gain more and more development momentum in the future. In new energy vehicles, due to the low voltage and current of the single battery, in order to meet the required voltage or power requirements, the single battery must be connected in series and parallel to meet different needs. Among various types of power batteries, lithium-ion batteries are widely used in power battery systems of new energy vehicles due to their advantages such as high energy density, long cycle life, and low self-discharge r...

AI Technical Summary

Problems solved by technology

The equalization circuit based on inductance has strong controllability of the equalization current and high equalization efficiency, but the inrush current of the MOS tube is large, which is likely to have an adverse effect on the battery

The capacitor-based equalization circuit has the advantages of fast equalization speed and high equalization efficiency, but the equalization process depends on the voltage difference of the single battery, and the voltage of the single battery cannot effectively reflect the inconsistency of the battery, so it is difficult to effectively achieve equalization

The LC resonant circuit is used for equalization, which can realize the equalization from monomer to monomer. The equalization speed is fast and the equalization efficiency is high, but there are many MOS tubes, high cost and complicated control.

The transformer-based equalization circuit uses a single-winding or multi-winding transformer to convert electric energy and magnetic energy to each other, and realizes bidirectional transmission of energy between monomers. The advantage of this equalization circuit is that the equalization speed is fast, but the structure is complex, the cost is high, and it is not easy to expand. , and there are problems such as winding transformer saturation, it is generally used in scenarios with a small number of single batteries

Cuk, Buck-Boost and other converters are used to form a bidirectional flyback DC-DC power converter. Its energy transmission is more flexible, and it can realize bidirectional flow of energy. The equalization speed is fast and it is easy to realize modularization. And the control signal is complex, there is a problem of magnetic loss of the winding, and the cost is high

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