Balance control system and method for high-capacity serial connected battery packs

Abstract

The invention relates to a balance control system combining electricity compensation with resistance dissipation in an energy storage system. The balance control system comprises battery packs, an electricity compensation balance control portion and a dissipation balance control portion. The balance scheme and the control mode include that each unit battery corresponds to an electricity compensation balance circuit, and the electricity compensation balance is started when the voltage of each unit battery is low; and simultaneously, each unit battery is connected in parallel with a dissipation resistor, and when the voltage of the individual battery is high during charging, dissipation control switches are started to enable the batteries to discharge through serial connected resistors, so that the battery packs and a compensation power supply are protected. Compared with a pure resistor dissipative balance scheme, the balance control system has the advantages that only the balance resistors of the individual batteries with high voltages work, so that the heat can be ignored, and heat management loads can be added. Energy of the compensation power supply is fully used, thermal losses are small, the energy conversion efficiency of a management system is improved greatly, a plurality of batteries can be balanced simultaneously, the balancing speed is increased, and the balancing time is shortened.

Description

technical field [0001] The present invention relates to a large-capacity series battery group equalization system and control method, which is applied to new energy power generation systems, smart grids, micro-grid power generation systems, bank ATMs and UPSs, etc., as energy storage media such as lithium-ion batteries and lead-acid batteries . Background technique [0002] The battery group equalization technology is one of the key technologies to ensure the normal operation of the energy storage system. Large-scale energy storage needs to connect multiple single cells in series and parallel to obtain larger energy storage capacity and higher power output. The energy storage capacity of the battery pack depends on the charging and discharging characteristics of the worst battery. Due to the discrete nature of the battery manufacturing process itself, and as the battery life increases, the mutual differences in battery performance become more prominent. If there is no bala...

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Problems solved by technology

The most commonly used energy dissipation type is the resistance shunt equalization method, such as figure 1 As shown, each battery is connected in parallel with a resistor, and the shunt current is controlled by controlling the balance switch. This method has a simple circuit and is easy to implement, but the shunt resistor will generate a lot of heat, which will increase the difficulty of thermal management and cause energy waste.

The energy non-dissipative type commonly used methods include inductance and power switching tube method, transformer energy transfer method and power supply equalization method: the inductance and power switching tube method is suitable for small current occasions; the transformer energy transfer method transfers energy to low voltage through the transformer In the battery, the energy of the battery is fully utilized in this scheme, and the equalization efficiency is high, but the secondary winding is difficult to match, and the leakage inductance of the transformer is difficult to control, which is not conducive to modularization; figure 2 As shown, the power supply equalization scheme uses the isolated power module to realize energy transfer, and realizes energy flow by controlling the isolated power module. This equalization method has high efficiency and is easy to control. However, if a single battery fails, it will be fully charged when charging. , the voltage is too high, according to the control strategy, other monomers must turn on the equalization circuit, and the long-term overload operation of the equalized power supply will cause power supply damage

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