Modularized layered fast equalization circuit

Abstract

The utility model discloses a modularized layered fast equalization circuit, comprising 4N batteries, the 4N batteries are connected in series, every four adjacent batteries form a battery pack, each battery pack is connected with an intra-pack equalization module to form a battery module, N battery modules are connected in series, each battery module is connected with an inter-pack equalization module, and the N inter-group equalization modules are connected in parallel. According to the utility model, the equalization time is shortened, and the equalization efficiency is improved. According to the utility model, a plurality of single batteries in the battery pack can be equalized, and a battery module composed of a plurality of single batteries can be equalized, so that the battery equalization accuracy and equalization efficiency are improved.

Description

Technical Field

[0001] This utility model relates to the field of battery power management technology, specifically to a modular, hierarchical, fast balancing circuit. Background Technology

[0002] To meet the input voltage and driving range requirements of electric vehicle power systems, lithium battery cells need to be combined into battery packs. After multiple charge-discharge cycles, the voltage or state of charge (SOC) of the power battery pack often becomes inconsistent. Inconsistency means that the voltage or SOC of individual cells is not exactly the same. During use, overcharging or over-discharging may occur, which will cause irreparable damage to the battery and seriously affect its lifespan.

[0003] Currently, traditional equalization circuits can only transfer energy between two adjacent cells, failing to achieve large-scale cell equalization. When the state of charge (SOC) difference exists between the first and last cells, the energy transfer path is relatively long. This leads to increased equalization time and reduced efficiency, failing to meet the requirements for rapid equalization. Utility Model Content

[0004] To address the technical problems in the background art, this utility model provides a modular layered fast balancing circuit, which can effectively improve the balancing efficiency of battery packs.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A modular hierarchical fast equalization circuit includes n batteries, including 4N batteries, which are connected in series. Every four adjacent batteries form a battery group. Each battery group is connected to an intra-group equalization module to form a battery module. N battery modules are connected in series. Each battery module is connected to an inter-group equalization module. N inter-group equalization modules are connected in parallel. Wherein, N is a natural number and N≥2.

[0007] Each of the group's equalization modules includes multiple inductors and multiple MOSFETs. MOSFETs Q1 to Q4 are connected in series to form a first-layer MOSFET group, and MOSFETs Q5 and Q6 are connected in series to form a second-layer MOSFET group. Both the first-layer and second-layer MOSFET groups are connected in parallel with the battery pack. The series connection node of MOSFETs Q1 and Q2 in the first-layer MOSFET group is connected to the series connection node of the first battery B1 and the second battery B2 through a first inductor L1. The series connection node of MOSFETs Q3 and Q4 is connected to the series connection node of the third battery B3 and the fourth battery B4 through a second inductor L2. The series connection node of MOSFETs Q2 and Q3 is connected to the series connection node of MOSFETs Q5 and Q6 through a third inductor L3. A diode is connected between the drain and source of each of the MOSFETs Q1 to Q6.

[0008] Each of the inter-group equalization modules includes a bidirectional flyback converter Ti, a MOSFET Q7-i, and a MOSFET Q8-i. The secondary side of the bidirectional flyback converter Ti is connected to the corresponding battery module i after the MOSFET Q7-i is connected in series at the same terminal. The primary side terminals of each bidirectional flyback converter Ti are interconnected at the same terminal, and the non-same terminals are interconnected after being connected in series with the MOSFET Q8-i. The drain and source of the MOSFET Q7-i are connected to a diode D7-i, and the drain and source of the MOSFET Q8-i are connected to a diode D8-i, where the diodes are natural numbers from 1 to N.

[0009] Furthermore, the 4N batteries are all of the same specification and model.

[0010] Furthermore, in each of the group's equalization modules, inductors L1, L2, and L3 are of the same type, and MOSFETs Q1 to Q6 have the same specifications and models; the drains of MOSFETs Q1 and Q5 in each group's equalization module are connected to the positive terminal of the first battery B1 in the battery pack of that group's equalization module, and the sources of MOSFETs Q4 and Q6 are connected to the negative terminal of the fourth battery B4 in the battery pack.

[0011] Furthermore, the bidirectional flyback converter Ti in each of the inter-group equalization modules has the same specifications and model; the MOSFETs Q7-i and Q8-i have the same specifications and model as MOSFET Q1.

[0012] Furthermore, it also includes a controller, which is connected to the gates of MOSFETs Q1 to Q6 in each group's equalization module, and is used to control the on and off states of MOSFETs Q1 to Q6; the controller is also connected to the gates of MOSFETs Q7-i and Q8-i in each group's equalization module, and is used to control the on and off states of MOSFETs Q7-i and Q8-i.

[0013] Furthermore, it also includes a voltage / SOC acquisition module, whose input terminal is connected to multiple batteries and whose output terminal is connected to the input terminal of the controller, transmitting the acquired battery voltage value or state of charge to the controller for processing.

[0014] Furthermore, in each of the inter-group equalization modules, the source of MOSFET Q7-i is connected to the negative terminal of the corresponding battery pack, and the drain is connected to the same-name terminal on the secondary side of the bidirectional flyback converter Ti. The source of MOSFET Q8-i is connected to the non-same-name terminal on the primary side of the bidirectional flyback converter Ti, and the drains of MOSFET Q8-i in each of the inter-group equalization modules are interconnected.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. This utility model uses modular equalization, which improves the charging equalization speed and equalization efficiency of the battery pack, and is suitable for battery packs composed of multiple batteries connected in series.

[0017] 2. This utility model can balance multiple individual cells within a group, as well as battery modules composed of multiple individual cells, thus improving the accuracy of battery balancing.

[0018] 3. This utility model has a simple and modular structure, which is easy to disassemble, inspect and assemble, improving the equalization effect of the battery pack and reducing the equalization time of the circuit. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of this utility model;

[0020] Figure 2 This is a schematic diagram of the Battery Equalization Module (BEM) in this utility model.

[0021] Figure 3 This is a schematic diagram of the structure in which a high-energy battery module charges a bidirectional flyback converter in the first working state of inter-group balancing in this utility model.

[0022] Figure 4This is a schematic diagram of the structure of the battery module group being charged and balanced by a bidirectional flyback converter in the first working state of the inter-group balancing of this utility model.

[0023] Figure 5 This is a schematic diagram of the structure in which the entire battery module group charges the bidirectional flyback converter in the second working state of inter-group balancing in this utility model.

[0024] Figure 6 This is a schematic diagram of the structure of charging equalization of the low-power module by the bidirectional flyback converter in the second working state of the inter-group equalization of this utility model.

[0025] Figure 7 This is a schematic diagram of the intra-group balancing process of this utility model, wherein Figure (a) is the energy storage and charging stage and Figure (b) is the energy release stage. Detailed Implementation

[0026] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that the specific embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0027] like Figure 1-7 As shown, a modular hierarchical fast equalization circuit includes 4N batteries connected in series. Every four adjacent batteries form a battery group, and each battery group is connected to an intra-group equalization module to form a battery module. N battery modules are connected in series, and each battery module is connected to an inter-group equalization module. The N inter-group equalization modules are connected in parallel. In this embodiment, N is 4, that is, there are 16 batteries connected in series. The 4N batteries have the same specifications and model, forming 4 battery modules connected in series, and 4 inter-group equalization modules are connected in parallel.

[0028] Each of the group's equalization modules includes multiple inductors and multiple MOSFETs. MOSFETs Q1 to Q4 are connected in series to form a first-layer MOSFET group, and MOSFETs Q5 and Q6 are connected in series to form a second-layer MOSFET group. Both the first-layer and second-layer MOSFET groups are connected in parallel with the battery pack. The series connection node of MOSFETs Q1 and Q2 in the first-layer MOSFET group is connected to the series connection node of the first battery B1 and the second battery B2 through a first inductor L1. The series connection node of MOSFETs Q3 and Q4 is connected to the series connection node of the third battery B3 and the fourth battery B4 through a second inductor L2. The series connection node of MOSFETs Q2 and Q3 is connected to the series connection node of MOSFETs Q5 and Q6 through a third inductor L3. A diode is connected between the drain and source of each of the MOSFETs Q1 to Q6.

[0029] In each of the group's equalization modules, inductors L1, L2, and L3 are of the same type, and MOSFETs Q1 to Q6 have the same specifications and models. The drains of MOSFETs Q1 and Q5 in each group's equalization module are connected to the positive terminal of the first battery B1 in the battery pack of that group's equalization module, and the sources of MOSFETs Q4 and Q6 are connected to the negative terminal of the fourth battery B4 in the battery pack.

[0030] Each of the inter-group equalization modules includes a bidirectional flyback converter Ti, a MOSFET Q7-i, and a MOSFET Q8-i. The secondary side of the bidirectional flyback converter Ti is connected to the corresponding battery module i after the MOSFET Q7-i is connected in series at the same terminal. The primary side terminals of each bidirectional flyback converter Ti are interconnected at the same terminal, and the non-same terminals are interconnected after being connected in series with the MOSFET Q8-i. A diode D7-i is connected between the drain and source of the MOSFET Q7-i, and a diode D8-i is connected between the drain and source of the MOSFET Q8-i, where i is a natural number from 1 to N.

[0031] In each of the inter-group equalization modules, the source of MOSFET Q7-i is connected to the negative terminal of the corresponding battery pack, and the drain is connected to the same-name terminal on the secondary side of the bidirectional flyback converter Ti. The source of MOSFET Q8-i is connected to the non-same-name terminal on the primary side of the bidirectional flyback converter Ti. The drains of MOSFET Q8-i in each of the inter-group equalization modules are interconnected.

[0032] The bidirectional flyback converter Ti in each of the inter-group equalization modules has the same specifications and model; the MOSFETs Q7-i and Q8-i have the same specifications and model as MOSFET Q1.

[0033] This invention also includes a controller, which is connected to the gates of MOSFETs Q1 to Q6 in each intra-group equalization module, and is used to control the on and off states of charge of MOSFETs Q1 to Q6. The controller is also connected to the gates of MOSFETs Q7-i and Q8-i in each inter-group equalization module, and is used to control the on and off states of charge of MOSFETs Q7-i and Q8-i. It also includes a voltage / SOC acquisition module, whose input terminals are connected to multiple batteries, and whose output terminal is connected to the input terminal of the controller, transmitting the acquired battery voltage values ​​or state of charge to the controller for processing.

[0034] The working principle of this utility model is as follows:

[0035] The equalization principle of this utility model is analyzed using a modular layered fast equalization circuit composed of 16 batteries in this embodiment. The equalization process of this utility model includes equalization between battery modules and equalization within battery modules.

[0036] Inter-module equalization includes two operating states, as detailed below:

[0037] The first operating state: The high-energy battery module charges the entire battery module group, performing equalization between the battery module groups, such as... Figure 3-4 As shown.

[0038] The controller collects the voltage or State of Charge (SOC) value of each battery in real time, and calculates the voltage or SOC value of each battery module (i.e., the series voltage or SOC value of the four batteries). The calculated values ​​are then sorted from highest to lowest. Assuming the voltage values ​​are sorted as battery module 1, battery module 3, battery module 2, and battery module 4, the controller selects battery modules 1 and 3 with higher voltage values ​​to release a portion of their energy to battery modules 1 through 4, thus initially balancing the electrical energy of battery modules 1 through 4. At this time, MOSFET Q7-1 in the inter-group balancing module connected to battery module 1 is turned on under the control of the controller. Battery module 1, MOSFET Q7-1, and bidirectional flyback converter T-1 form a current loop. Battery module 1 releases a portion of its charge to charge the windings of bidirectional flyback converter T-1. When the discharge threshold is reached, MOSFET Q7-1 is turned off, and MOSFET Q8-1 is turned on under the control of the controller to perform equalization charging for battery modules 1 through 4.

[0039] Similarly, in the inter-group equalization module connected to battery module 3, MOSFET Q7-3 is turned on under the control of the controller. Battery module 3, MOSFET Q7-3 and bidirectional flyback converter T-3 form a current loop. Battery module 3 discharges to charge the winding of bidirectional flyback converter T-3. When the discharge threshold is reached, MOSFET Q7-3 is turned off, and MOSFET Q8-3 is turned on under the control of the controller to perform equalization charging for battery modules 1 to 4.

[0040] The second state: The entire battery module group charges the low-energy module group, continuing the balancing process between battery module groups, such as... Figure 5-6 As shown.

[0041] At this point, after passing through the first working state, the MOSFET Q8-2 in the inter-group equalization module connected to battery module 3 needs to be turned on under the control of the controller. The entire battery module group and the bidirectional flyback transformer winding T-2 form a current loop to charge the bidirectional flyback converter T-2. When the discharge threshold is reached, the MOSFET Q8-2 is turned off, and the MOSFET Q7-2 is turned on under the control of the controller to charge battery module 2.

[0042] Similarly, in the inter-group equalization module connected to battery module 4, MOSFET Q8-4 is turned on under the control of the controller. The entire battery module group, MOSFET Q8-4 and bidirectional flyback converter winding T-4 form a current loop. When the discharge threshold is reached, MOSFET Q8-4 is turned off, and MOSFET Q7-4 is turned on under the control of the controller to charge battery module 4.

[0043] The intra-group balancing process of the battery modules is as follows: Figure 7 As shown.

[0044] The balancing within each battery module is primarily achieved through the coordination of MOSFETs Q1 to Q6. MOSFETs Q5 and Q6 regulate and shorten the energy transfer path between batteries, ensuring that only the two batteries with higher and lower energy levels experience SOC changes within a balancing cycle. The intermediate cells (e.g., B2 and B3) remain essentially unchanged; the intermediate nodes (e.g., B2 and B3) merely act as "bridges" for energy transfer. This means that within a balancing cycle, B2 and B3 both charge and discharge, but these two processes essentially cancel each other out, resulting in a net SOC change close to zero. The design does not emphasize direct charging of B3 by B2; instead, it utilizes the entire module's energy transfer path to achieve direct energy transfer between the endpoint batteries (high and low SOC), thus minimizing the net energy change at the intermediate nodes.

[0045] Assuming that the SOC of B4 is higher than that of B1, there are two possible operating states:

[0046] Energy storage charging stage: When the three MOSFETs Q2, Q4, and Q6 are simultaneously turned on, the battery packs B2, B3, and B4 together establish a magnetic field for the parallel-connected energy storage inductors L1-L3 to store energy. By monitoring the inductor current in real time, the system immediately switches states when the preset peak threshold is reached.

[0047] Energy release phase: While turning off all MOSFETs, the freewheeling characteristic of the inductor current is utilized to allow the stored electrical energy to reverse charge and compensate the target battery B1 and intermediate batteries B2 and B3 through the unidirectional conduction circuit formed by the diodes in each branch. Among them, B4 serves as the main power supply, and its energy is indirectly transferred to B1 through this topology. B2 and B3 simultaneously participate in energy transfer and receive reverse charging during this process, forming a cascaded energy redistribution mechanism.

[0048] To verify the balancing time and efficiency of this invention, 16 identical batteries were connected in series and balanced using a traditional balancing circuit, such as... Figure 5 As shown in the table below, the experimental data using this invention and the traditional equalization circuit are as follows:

[0049] Experimental data of this invention and traditional equalization circuits

[0050] 16 batteries in series This utility model's equalization circuit Traditional equalization circuit Charging equalization time 192s 1200s Static Equilibrium Efficiency 200s 1350s Discharge equalization time 206s 1450s

[0051] As can be seen from the data in the table above, the equalization circuit of this utility model reduces the charging equalization time by 84%, increases the static equalization efficiency by 6.75 times, and reduces the discharge equalization time by 85%.

Claims

1. A modular hierarchical fast equalization circuit, characterized in that: It includes 4N batteries, which are connected in series. Every four adjacent batteries form a battery group. Each battery group is connected to an intra-group balancing module to form a battery module. N battery modules are connected in series. Each battery module is connected to an inter-group balancing module. The N inter-group balancing modules are connected in parallel. Each of the group's equalization modules includes multiple inductors and multiple MOSFETs. MOSFETs Q1 to Q4 are connected in series to form a first-layer MOSFET group, and MOSFETs Q5 and Q6 are connected in series to form a second-layer MOSFET group. Both the first-layer and second-layer MOSFET groups are connected in parallel with the battery pack. The series connection node of MOSFETs Q1 and Q2 in the first-layer MOSFET group is connected to the series connection node of the first battery B1 and the second battery B2 through a first inductor L1. The series connection node of MOSFETs Q3 and Q4 is connected to the series connection node of the third battery B3 and the fourth battery B4 through a second inductor L2. The series connection node of MOSFETs Q2 and Q3 is connected to the series connection node of MOSFETs Q5 and Q6 through a third inductor L3. A diode is connected between the drain and source of each of the MOSFETs Q1 to Q6. Each of the inter-group equalization modules includes a bidirectional flyback converter Ti, a MOSFET Q7-i, and a MOSFET Q8-i. The secondary side of the bidirectional flyback converter Ti is connected to the corresponding battery module i after the MOSFET Q7-i is connected in series at the same terminal. The primary side terminals of each bidirectional flyback converter Ti are interconnected at the same terminal, and the non-same terminals are interconnected after being connected in series with the MOSFET Q8-i. A diode D7-i is connected between the drain and source of the MOSFET Q7-i, and a diode D8-i is connected between the drain and source of the MOSFET Q8-i, where i is a natural number from 1 to N.

2. A modular layered fast equalization circuit according to claim 1, characterized in that: The 4N batteries have the same specifications and model.

3. The modular layered fast equalization circuit of claim 1, wherein: In each of the group's equalization modules, inductors L1, L2, and L3 are of the same type, and MOSFETs Q1 to Q6 have the same specifications and models. The drains of MOSFETs Q1 and Q5 in each group's equalization module are connected to the positive terminal of the first battery B1 in the battery pack of that group's equalization module, and the sources of MOSFETs Q4 and Q6 are connected to the negative terminal of the fourth battery B4 in the battery pack.

4. The modular layered equalization circuit of claim 1, wherein: The bidirectional flyback converter Ti in each of the inter-group equalization modules has the same specifications and model; the MOSFETs Q7-i and Q8-i have the same specifications and model as MOSFET Q1.

5. The modular layered equalization circuit of claim 1, wherein: It also includes a controller, which is connected to the gates of MOSFETs Q1 to Q6 in each group's equalization module and is used to control the on and off states of MOSFETs Q1 to Q6; the controller is also connected to the gates of MOSFETs Q7-i and Q8-i in each group's equalization module and is used to control the on and off states of MOSFETs Q7-i and Q8-i.

6. A modular hierarchical fast equalization circuit according to claim 5, wherein: It also includes a voltage / SOC acquisition module, whose input terminal is connected to multiple batteries and whose output terminal is connected to the input terminal of the controller, transmitting the acquired battery voltage value or state of charge to the controller for processing.

7. The modular layered equalization circuit of claim 1, wherein: In each of the inter-group equalization modules, the source of MOSFET Q7-i is connected to the negative terminal of the corresponding battery pack, and the drain is connected to the same-name terminal on the secondary side of the bidirectional flyback converter Ti. The source of MOSFET Q8-i is connected to the non-same-name terminal on the primary side of the bidirectional flyback converter Ti. The drains of MOSFET Q8-i in each of the inter-group equalization modules are interconnected.

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