Equalization circuit based on Buck-Boost convertor and bidirectional LC (inductance capacitance) resonant convertor as well as implementation method

Abstract

The invention discloses an equalization circuit based on a Buck-Boost convertor and a bidirectional LC (inductance capacitance) resonant convertor as well as an implementation method. The equalization circuit comprises a microcontroller, the Buck-Boost convertor, the bidirectional LC resonant convertor, an option switch module, an equalization busbar, a battery pack and filter capacitors. According to the equalization circuit, by means of control of output voltage of the Buck-Boost convertor as well as the bidirectional LC resonant convertor, soft switching equalization of Pack to Cell or Cell to Pack can be realized, the equalization circuit has the advantages of high efficiency, simplicity in control, small size, switching loss avoidance, easiness in modularization and the like, and the defect that the traditional Pack to Cell equalization circuit cannot deal with the condition that certain cell in a pack has higher voltage while other cells are in equalization is overcome.

Description

technical field [0001] The invention relates to an equalization circuit based on Buck-Boost conversion and bidirectional LC resonance conversion and a realization method. Background technique [0002] The world is facing an unprecedented energy and environmental crisis, which has attracted worldwide attention. Electric vehicles have the characteristics of energy saving and environmental protection, which is the key way to solve this major crisis, and has become an inevitable trend in the future development of the automobile industry. Large-scale electric vehicles as mobile energy storage equipment will be an important pillar of the third industrial revolution (Energy Internet). Lithium-ion batteries are widely used as power sources in electric vehicles and hybrid electric vehicles because of their high energy density, low discharge rate and no memory effect. However, due to the technical constraints of battery manufacturing technology and power management system, a large n...

AI Technical Summary

Problems solved by technology

However, in this equalization circuit, when the voltage of a certain battery cell is low, while the voltage of other battery cells is in a balanced state, one switch is required to complete the equalization; High, and when the voltage of other cells is in balance, n-1 switching cycles are required to complete the balance

Therefore, the Pack to Cell equalization circuit needs n / 2 switching cycles on average, the equalization speed is slow, and the efficiency is low. It is only suitable for one or several battery cells in the battery pack with low voltage and other battery cells. When the voltage is in a balanced state, it is not suitable for the case where one or several battery cell voltages are high and other battery cell voltages are in a balanced state

For the Cell to Pack type equalization circuit, when the voltage of a certain battery cell is relatively high, while the voltage of other battery cells is in balance, one switch is required to complete the equalization; when the voltage of a certain battery cell is relatively high Low, and when the voltage of other battery cells is in a balanced state, n-1 switching cycles are required to complete the equalization. Therefore, the Cell to Pack type equalization circuit needs n / 2 switching cycles on average, and the equalization speed is slow and the efficiency is low. This method is only suitable for the situation that one or several cells of the battery pack have a higher voltage and the other cells are in a balanced state, and it is not suitable for one or several cells with a lower voltage and the other cells are in a balanced state. The case where the body voltage is in equilibrium

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