CN-121984170-A - Energy storage battery pack internal impedance excitation and active equalization system

Abstract

The invention relates to an impedance excitation and active equalization system in an energy storage battery pack, belongs to the technical field of battery management and power electronics, and solves the problems that the impedance measurement of the existing battery management system needs to be carried out offline and is independent of an energy equalization function, and the system complexity and the resource waste are high. The technical scheme comprises a series battery Pack module, a matrix switch module, a bidirectional active bridge DAB converter, a current sampling module and a control module, wherein a battery Pack is selectively connected through the matrix switch, the DAB converter is injected with specific frequency current excitation for online impedance measurement, and internal impedance spectrum parameters are calculated by combining current sampling, and meanwhile energy active equalization among the batteries Pack is realized. The invention integrates two functions under the same hardware structure, does not need additional equipment, remarkably improves the integration level, the running consistency and the battery life of the battery pack management system, and is suitable for on-line monitoring and energy optimization management.

Inventors

• WANG HANFEI
• LI YUWANG
• WANG PING
• CHEN ZHIYU
• LI JIAN
• XIAO YANLIN
• CHEN SIRUI
• YANG LIJUN
• WANG JUE
• WEI YI

Assignees

• 重庆大学

Dates

Publication Date

20260505

Application Date

20260126

Claims (6)

1. 1. An energy storage battery pack internal impedance excitation and active equalization system is characterized by comprising: The serial battery Pack module is formed by connecting a plurality of battery packs (Pack) in series; The matrix switch module is electrically connected with the series battery Pack module and is used for selectively connecting any battery Pack or a plurality of battery packs Pack into the energy exchange loop under the action of a control signal; the current sampling module is used for acquiring the current of the series battery Pack and the branch current information of the selected battery Pack; The bidirectional active bridge DAB converter is electrically connected with the matrix switch module and is used for charging or discharging the selected battery Pack to generate specific frequency current for measuring the internal impedance spectrum and realizing energy balance of each battery Pack in the series battery Pack; The control module is respectively connected with the matrix switch module, the bidirectional active bridge DAB converter and the current sampling module, and is used for selecting a target battery Pack through the matrix switch module, controlling the bidirectional active bridge DAB converter to charge or discharge the target battery Pack, and determining the cell current flowing in the target battery Pack based on the current signal.
2. 2. The system of claim 1, wherein the Pack is a single cell of a series battery Pack, comprising one or more cells, and capable of being independently accessed, measured, and energy conditioned.
3. 3. The system for stimulating and actively equalizing the internal impedance of an energy storage battery Pack according to claim 1, wherein said matrix switch module selectively conducts the battery Pack in the series battery Pack under the control signal of the control module, so that the target battery Pack is connected to the energy processing circuit.
4. 4. The system for impedance excitation and active equalization in an energy storage battery Pack according to claim 1, wherein said current sampling module comprises a first current sampling unit A1 arranged in a common loop of a series battery Pack and a second current sampling unit A2 arranged in a Pack branch of a target battery Pack, and the calculation relationship is that, based on the currents collected by the first current sampling unit and the second current sampling unit, the current flowing through the battery cells in the Pack of the target battery Pack is determined Where I int represents the current flowing through the cells in the target battery Pack, I total represents the total current in the common loop of the series battery packs, and I branch represents the current in the corresponding leg of the target battery Pack.
5. 5. The system of claim 1, wherein the control module adjusts the phase shift angle Controlling a bidirectional active bridge DAB converter to inject specific-frequency current excitation into a target battery Pack, wherein the injection current and the phase shift angle meet the relation Wherein I exc (t) represents the current excitation injected by the bi-directional active bridge DAB converter into the target battery Pack, (T) represents the phase shift angle with time, V 1 and V 2 represent the DAB primary side and secondary side voltages, g # ) In the energy balancing process, the bidirectional active bridge DAB converter transfers energy among different battery packs, and determines a target battery Pack which needs to be subjected to energy balancing according to the energy state parameters of each battery Pack, wherein the energy state difference meets the following requirements Wherein SOC i represents the energy state difference of the ith battery Pack, SOC i represents the energy state parameter of the ith battery Pack, SOC ref represents the preset reference energy state parameter, and the energy transfer amount and the balance voltage, the balance current and the balance time satisfy the relation Wherein E represents energy transferred during energy equalization, V b (t) represents equalization voltage over time during equalization, I b (t) represents equalization current over time during equalization, and t b represents duration of energy equalization.
6. 6. The system for stimulating and actively equalizing an impedance in an energy storage battery Pack according to claim 1, wherein said control module obtains a terminal voltage V r1 ,V r2 ,...,V rn of a cell in a target battery Pack and calculates an impedance parameter of the cell in the target battery Pack based on the terminal voltage and a current flowing through the cell in the target battery Pack, the calculation relationship is Wherein Z ri represents the impedance parameter of the ith cell in the target battery Pack, V ri represents the terminal voltage of the ith cell in the target battery Pack, I int represents the current flowing through the ith cell in the target battery Pack, and the control module estimates the required energy transfer amount based on the energy state difference of the battery Pack, the energy transfer amount and the energy state difference satisfying the relationship Where Δe i represents the energy that the ith battery Pack needs to transfer, Δsoc i represents the SOC difference of the ith battery Pack relative to the reference energy state, and E rated,i represents the rated energy of the ith battery Pack.

Description

Energy storage battery pack internal impedance excitation and active equalization system Technical Field The invention belongs to the technical field of battery management and power electronics, and relates to an internal impedance excitation and active equalization system of an energy storage battery pack. Background With the rapid development of new energy automobiles, energy storage systems and distributed energy devices, the reliability and safety of the operation of a lithium battery pack serving as a core energy storage unit are increasingly concerned. In practical application, the battery pack is generally formed by connecting a large number of battery cells in series, and due to factors such as manufacturing process discreteness, working environment difference, aging degree non-uniformity deviation can occur among all the battery cells or battery packs in the battery pack in aspects of internal resistance, capacity, energy state and the like. The deviation is accumulated continuously in the recycling process, so that the whole performance of the battery pack is attenuated and accelerated, and even potential safety hazards such as thermal runaway and the like are caused. The internal resistance of the battery is a key parameter representing the state of health and dynamic characteristics of the battery, and the change of the internal resistance can reflect the aging degree, the temperature condition and the load working condition of the battery. The method realizes accurate measurement of the internal resistance and has important significance for battery health state evaluation, fault early warning and energy management optimization. However, most of the existing impedance test schemes rely on external test equipment or additional excitation sources, and the battery is usually required to be in an off-line or non-working state for measurement, so that the requirement of continuous on-line monitoring of the battery pack is difficult to be met. To improve the problem of the internal energy maldistribution of the battery pack, the conventional battery management system BMS generally adopts an energy balancing technique. The passive equalization method realizes voltage consistency by dissipating redundant energy through the resistor, and has the advantages of simple structure, low energy utilization efficiency and easiness in heat generation. The active equalization method can effectively improve the system efficiency by adjusting the energy state of each battery unit in an energy transfer mode, but the existing scheme focuses on energy adjustment per se, the equalization path and the control strategy are relatively fixed, and the real-time sensing and comprehensive utilization of battery health parameters are lacking. In current battery management system BMS designs, impedance measurement and energy balancing are typically implemented as separate functional modules. The impedance measurement requires additional excitation circuitry and sampling devices, and current and power information generated during the energy equalization process is underutilized for state estimation. The design thought of the function separation not only increases the complexity and cost of system hardware, but also limits the improvement of the health management capability of the battery pack, and is difficult to meet the requirement of the battery management system on the development of high integration and intelligent direction. Therefore, a new system scheme is urgently needed in the field, and the existing energy conversion structure can be fully utilized under the condition that a battery pack is in a normal running state and a complex external testing device is not introduced, so that the on-line measurement of the impedance of a battery pack and the energy balance operation are synchronously realized, and the overall integration level, running consistency and intelligent level of a battery pack management system are improved. Disclosure of Invention Accordingly, the present invention is directed to an impedance excitation and active equalization system in an energy storage battery. In order to achieve the above purpose, the present invention provides the following technical solutions: An energy storage battery internal impedance excitation and active equalization system comprising: The serial battery Pack module is formed by connecting a plurality of battery packs (Pack) in series; The matrix switch module is electrically connected with the series battery Pack module and is used for selectively connecting any battery Pack or a plurality of battery packs Pack into the energy exchange loop under the action of a control signal; the current sampling module is used for acquiring the current of the series battery Pack and the branch current information of the selected battery Pack; A bidirectional active bridge (Dual Active Bridge, DAB) converter electrically connected to the matrix switch module for charging or discharging sele