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Hierarchical equalization circuit system and hybrid control method based on series battery pack

A technology of connecting battery packs and balancing circuits in series, applied in charge balancing circuits, battery circuit devices, charging/discharging of secondary batteries, etc., can solve problems such as increased circuit loss and cost, high current stress, battery imbalance, etc. The effect of balancing the number of circuits, increasing battery energy, and reducing system energy loss

Inactive Publication Date: 2018-06-26
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, regardless of whether it is based on SOC or battery voltage, the equalization system must perform a corresponding equalization operation after a certain unbalanced deviation occurs between the two.
In other words, when the equalization circuit starts to work, the unbalanced battery has already occurred, which means that the health status of the battery has been damaged at this time. If the equalization cannot be completed before the battery is discharged / charged to the allowed capacity threshold, the system will be available. energy reduction
In order to eliminate the imbalance in the shortest possible time, the equalization circuit has to withstand high current stress, which increases the loss and cost of the circuit

Method used

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  • Hierarchical equalization circuit system and hybrid control method based on series battery pack
  • Hierarchical equalization circuit system and hybrid control method based on series battery pack
  • Hierarchical equalization circuit system and hybrid control method based on series battery pack

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Effect test

Embodiment 1

[0068] figure 2 A hierarchical equalization architecture diagram based on series battery packs is given. The system is divided into top-level and bottom-level equalization structures. The bottom layer adopts a C2C equalization architecture. Every two adjacent battery cells are equalized by an equalization circuit. The input and output ends of the circuit are respectively connected to two adjacent battery cells. The circuit topology can choose bidirectional converters such as bidirectional Buck Boost, bidirectional Cuk, and switched capacitors. The n battery cells are divided into m battery packs, and each battery pack contains p battery cells (p=n / m, if there is a remainder, round up to an integer). On this basis, each battery pack is connected to one winding of a multi-winding transformer through a power conversion circuit (such as half-bridge, full-bridge, push-pull, etc.), so as to couple with other battery packs and perform energy transfer, forming a multi-directional mul...

Embodiment 2

[0072] Figure 4 The topological structure of the top-level equalization circuit of the present invention is given. The circuit is based on the phase-shifted half-bridge topology, the first switching tube Q i_1 and the second switch Q i_2 (i=1, 2, . . . , m) are connected in series to form a bridge arm, and the two switching tubes are turned on complementary with a 50% duty cycle. The first resonant capacitor C i_1 with the second resonant capacitor C i_2 Connected in series to form another bridge arm. Inductance L r_i It is the leakage inductance of the transformer, which is connected in series with one winding of the transformer at the midpoint of the two bridge arms. Each winding of the transformer is coupled to other windings through a magnetic core. When energy needs to be transferred between any two battery packs, taking the 1st and mth as an example, the main BMS sends a PWM signal to make Q 1_1 and Q m_1 They are conducted at a certain phase shift angle, and t...

Embodiment 3

[0075] Figure 7 , Figure 8 The block diagram and control flow chart of the hybrid control mode of the present invention are given respectively.

[0076] The voltage, charge and discharge current, and temperature information of each battery cell are obtained by sampling from the BMS, and the battery capacity, SOC, SOC change rate, and current acceptance rate are estimated. When the battery is in a static state, the main BMS uses the SOC as the control object; when the battery is in the working state, uses the SOC change rate as the control object to calculate the operating current reference corresponding to each equalization circuit.

[0077] It can be seen from Figure 1(a) that in the underlying C2C architecture equalization system, the equalization current I flowing through the i-th battery cell b_i It is equal to the working current I of two adjacent balancing circuits of the battery c_i , I c_i-1 And the difference between the working current of the top-level equalizati...

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Abstract

The invention discloses a layered equalizing circuit system based on a series battery stack and a hybrid control method, and belongs to the technical field of battery energy storage systems. A bottom layer of the architecture adopts an adjacent cell-cell (C2C) structure, and is divided into different battery packs. A top layer adopts a transformer coupled multi-directional multi-port converter, and bidirectional energy flow among arbitrary battery packs of the bottom layer is realized. The layered architecture can reduce the amount of equalizing circuits working simultaneously, so that the repeated charging and discharging problem of the batteries in the equalizing process is avoided, and the health status of the batteries is improved. According to the hybrid control method, during the standing of the batteries, the equalizing current required for each battery cell is obtained by calculating SOC, so that an equalizing system is controlled; when the batteries work, each equalizing circuit is controlled by calculating SOC change rate, so that a potential unequalizing tendency is forecasted in advance and is corrected, and real-time equalizing for each battery is guaranteed. Moreover, according to the layered architecture and the control method, the rated current required for the equalizing circuit can be reduced, so that the system cost is reduced, and the energy loss is reduced.

Description

technical field [0001] The invention discloses a layered equalization circuit system and a hybrid control method based on series battery packs, belonging to the technical field of battery energy storage systems. Background technique [0002] In recent years, with the rapid development of electric vehicles, hybrid vehicles and new energy power generation and energy storage systems, the importance of batteries has become increasingly prominent. Due to the limited voltage of battery cells, series battery packs are widely used to meet the voltage level requirements of the above systems. However, due to different factors such as production conditions, working environment, aging speed and internal chemical characteristics, there will be capacity imbalance among the cells in the series battery pack, which seriously affects the energy utilization rate of the battery pack, battery life and system performance. Safety. Therefore, it is of great significance to add an equalization mec...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M10/42H01M10/44H02J7/00
CPCH01M10/4207H01M10/441H01M2010/4271H02J7/0016Y02E60/10
Inventor 桂涵东王栋顾东杰张之梁
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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