Battery balancing circuit and its control method based on multi-phase interleaved converter

Abstract

The invention discloses a multiphase interleaved converter based battery equalization circuit and a control method therefor. The equalization circuit comprises a controller, a plurality of half-bridge circuits, a plurality of electric reactors and a plurality of battery cells. The half-bridge circuits are all connected in parallel to two ends of a battery pack; and a middle point of each half-bridge circuit is connected with a negative electrode of a battery cell through an electric reactor. According to the circuit, MOS transistors of the half-bridge circuits are controlled by judging the magnitude of average voltage of the battery cells on the upper and lower sides of an inductor and average voltage of the battery pack, so that the equalization of any battery cell to any battery cell is realized. The circuit has the advantages of high equalization efficiency, simplicity for control, small volume, easiness for modularization and the like, and solves difficult problems of low equalization current and difficulty in realizing zero voltage difference equalization for a conventional Cell to Cell type equalization circuit.

Description

technical field [0001] The invention relates to a battery balancing circuit based on a multi-phase interleaving converter and a control method thereof. Background technique [0002] Energy, the environment and resources are the basic conditions for the survival and development of human beings. However, it is an indisputable fact that the world's oil resources are becoming increasingly depleted and the ecological environment is seriously deteriorating, which seriously restricts the sustainable development of the economy and society. It is a serious problem that countries all over the world must face . Lithium-ion batteries play an irreplaceable role in solving the energy and environmental crisis due to their outstanding advantages such as high energy density, long cycle life, no memory effect, high cost performance and high single voltage. In practical applications, the use of lithium-ion batteries often adopts the form of series-parallel combination, but due to the inconsis...

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Problems solved by technology

However, the main problem of this equalization circuit is: when the battery pack charges and balances the battery cell with the lowest voltage, it also discharges the battery cell at the same time, and the balanced net current is small, which also causes unnecessary energy waste

[0008] (1) The open circuit voltage of lithium-ion batteries is relatively flat when the SOC is between 30% and 70%. Even if the SOC differs greatly, the corresponding voltage difference is very small. The equalization current is very small, which may even cause the power electronic devices to fail to conduct normally;

[0009] (2) Due to the conduction voltage drop of power electronic devices, it is difficult to achieve zero voltage difference balance between battery cells

[0010] (3) The traditional equalization circuit either needs a lot of switches to switch, or needs a lot of energy storage devices such as reactors, capacitors, and transformers, resulting in a large volume of the equalization circuit, complicated control, and poor practicability

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