A series-parallel hybrid battery system

Abstract

This invention discloses a series-parallel hybrid battery system, which adopts a parallel-then-series approach. Each individual battery cell is connected to a cell monitoring module for detecting its voltage, current, and temperature. When a cell cell malfunctions, it can be disconnected through the corresponding monitoring module, thereby preventing parallel circulating currents within the parallel units and avoiding thermal runaway, ensuring safe and stable operation of the battery system. In this invention, a battery cluster management unit, in conjunction with other battery management units, controls the active balancing between the parallel units. The battery cluster management unit also manages the number of disconnected cells in each parallel unit, ensuring that the difference in the number of disconnected cells between different parallel units is less than or equal to a set value. This eliminates the capacity bottleneck problem between series-connected parallel units, enabling the battery system to operate stably and reliably.

Description

Technical Field

[0001] This invention belongs to the field of electronic technology, and in particular relates to a series-parallel hybrid battery system. Background Technology

[0002] In the battery field, battery systems can be categorized into pure series battery systems, pure parallel battery systems, and hybrid series-parallel battery systems based on the connection method of each individual cell. Pure series and pure parallel battery systems are relatively limited in large-capacity applications, such as energy storage power stations; currently, hybrid series-parallel battery systems are more commonly used.

[0003] Existing series-parallel hybrid battery systems generally employ two methods: series first, then parallel, and parallel first, then series.

[0004] Series-parallel hybrid battery systems, such as... Figure 3 As shown, individual cells BAT101-BAT104 are connected in series with a DC / DC module to form the first parallel branch; individual cells BAT105-BAT108 are connected in series with a DC / DC module to form the second parallel branch; and individual cells BAT109-BAT1012 are connected in series with a DC / DC module to form the third parallel branch. Each individual cell in each parallel branch is managed by a BMS (Battery Management System). This series-parallel hybrid battery system, with multiple individual cells directly connected in series in each parallel branch, places extremely stringent reliability requirements on both the individual cells and the BMS. A large number of cells connected in series means an exponentially increasing failure rate (if one individual cell fails, it can quickly affect the other cells connected in series with it). Furthermore, the capacity bottleneck effect is particularly pronounced among the individual cells connected in series in each parallel branch; in actual use, there have been instances where a 3% lag in individual cell capacity has caused a significant drop in the overall battery system capacity. The balancing capability of BMS is a core pain point. Currently, there are solutions that combine active and passive balancing with manual maintenance-level strong balancing, but these solutions are costly and inefficient.

[0005] Series-parallel hybrid battery systems, such as those that first connect in parallel and then in series. Figure 4As shown, individual cells BAT201-BAT203 are connected in parallel to form the first parallel unit, individual cells BAT204-BAT206 are connected in parallel to form the second parallel unit, individual cells BAT207-BAT209 are connected in parallel to form the third parallel unit, and individual cells BAT210-BAT212 are connected in parallel to form the fourth parallel unit. These parallel units are then connected in series. Individual cells BAT201-BAT212 are also connected in series with switches SW201-SW212 respectively. This series-parallel hybrid battery system, with parallel cells connected in parallel first and then series, suffers from problems such as battery capacity degradation, the risk of single-point fault propagation, and excessively high maintenance costs due to the presence of bias current or even parallel circulating current within each parallel unit. These are core challenges for power batteries and energy storage systems. Furthermore, the capacity bottleneck effect is still unavoidable among the parallel units connected in series. Summary of the Invention

[0006] The purpose of this invention is to provide a series-parallel hybrid battery system that can control the bias current or parallel circulating current inside the parallel unit, eliminate the capacity bottleneck effect of each parallel unit connected in series, and ensure that the entire battery system is safe and stable.

[0007] To achieve the above objectives, the solution of the present invention is:

[0008] A series-parallel hybrid battery system includes multiple parallel units connected in series, each parallel unit having multiple individual batteries connected in parallel; in each parallel unit, each individual battery is connected to an individual battery monitoring module, and each parallel unit is equipped with a battery management unit; the individual battery monitoring modules in the same parallel unit are interconnected and communicate with each other and with the corresponding battery management unit; each battery management unit is equipped with an active balancing circuit, and the active balancing circuits of each battery management unit are connected together through a balancing bus; the battery management units are interconnected and communicate with each other and with a battery cluster management unit.

[0009] Each individual battery monitoring module is used to detect the voltage, current, and temperature of the corresponding individual battery. Each individual battery monitoring module has the same first current setting value, the same voltage setting value, and the same first disconnection condition. Each battery management unit has the same second current setting value, the same second current duration setting value, the same first temperature setting value, the same first temperature duration setting value, the same second temperature setting value, and the same second disconnection condition. The first disconnection condition is that the voltage of the individual battery is higher than the voltage setting value and / or the current of the individual battery is higher than the first current setting value. The second disconnection condition is that the current of the individual battery is higher than the second current setting value and the duration exceeds the second current duration setting value, or / and the temperature of the individual battery is higher than the first temperature setting value and the duration exceeds the first temperature duration setting value, or / and the temperature of the individual battery is higher than the second temperature setting value. When an individual battery meets the first disconnection condition, its corresponding individual battery monitoring module automatically disconnects the individual battery. When an individual battery meets the second disconnection condition, the corresponding battery management unit controls the corresponding individual battery monitoring module to disconnect the individual battery.

[0010] The battery cluster management unit compares the voltages of each parallel unit. When the voltage difference between any two parallel units reaches the voltage imbalance set value, it sends a start balancing command to each battery management unit to control its active balancing circuit to start working. The power is transferred between them through the balancing bus to achieve power balancing between each parallel unit.

[0011] The battery cluster management unit centrally manages the number of individual batteries disconnected in each of the parallel units. If the sum of the number of individual batteries in a parallel unit that meet the first disconnection condition and the second disconnection condition exceeds the disconnection difference setting value set by the battery cluster management unit, then the battery cluster management unit controls other parallel units to disconnect a certain number of individual batteries, so that the difference in the number of individual batteries disconnected between different parallel units is less than or equal to the disconnection difference setting value.

[0012] Furthermore, each of the individual battery monitoring modules is equipped with an MCU, a voltage sampling circuit, a current sampling circuit, a temperature sampling circuit, a switching circuit, and a communication module. The voltage sampling circuit, the current sampling circuit, and the temperature sampling circuit are respectively connected to the corresponding detection input terminals of the MCU. The switching circuit includes a drive circuit and an electronic switch. The input terminal of the drive circuit is connected to the control output terminal of the MCU. The electronic switch is connected in series in the charging and discharging circuit of the corresponding individual battery. The output terminal of the drive circuit is connected to the control terminal of the electronic switch. The MCU communicates with the corresponding battery management unit through the communication module.

[0013] Furthermore, the electronic switch is a unidirectional switch, or the electronic switch is a combination of bidirectional electronic switches.

[0014] Furthermore, when the MCU detects that its corresponding single battery cell meets the first disconnection condition, the MCU outputs a control signal to the drive circuit, and the drive circuit drives the electronic switch to disconnect the charging and discharging circuit of the corresponding single battery cell.

[0015] When a single cell meets the second disconnection condition, the corresponding battery management unit determines that the single cell has thermal runaway. The battery management unit then outputs a control command to the corresponding single cell monitoring module. The MCU of the corresponding single cell monitoring module outputs a control signal to the drive circuit, which drives the electronic switch to disconnect the charging and discharging circuit of the corresponding single cell.

[0016] Furthermore, when the sum of the number of individual cells in a parallel unit that meet the first disconnection condition and the number of individual cells that meet the second disconnection condition does not exceed the disconnection difference setting value, the battery management unit corresponding to a certain parallel unit controls the corresponding individual cell monitoring module to disconnect the individual cells that meet the first disconnection condition and the individual cells that meet the second disconnection condition.

[0017] When other parallel units are working normally, if the number of disconnected individual cells in a certain parallel unit has reached the disconnection difference setting value, and a new individual cell that meets the first or second disconnection condition is added to this parallel unit, then the battery cluster management unit issues an equalization command to the battery management unit corresponding to the other parallel units. The battery management unit corresponding to the other parallel units controls the corresponding parallel units to first disconnect the same number of individual cells that meet the first or second disconnection condition. Only after this number of individual cells that meet the first or second disconnection condition are disconnected in this parallel unit can the new individual cells that meet the first or second disconnection condition be allowed to disconnect, thereby ensuring that the difference in the number of disconnected individual cells between different parallel units is less than or equal to the disconnection difference setting value.

[0018] When other parallel units are operating normally, if the sum of the number of individual cells in a certain parallel unit that meet the first disconnection condition and the second disconnection condition is greater than the disconnection difference setting value, then the battery cluster management unit issues an equalization command to the battery management units corresponding to the other parallel units. The battery management units corresponding to the other parallel units then control their respective parallel units to disconnect a certain number of individual cells first. Only then are the individual cells in this parallel unit that meet the first disconnection condition and the second disconnection condition allowed to disconnect, thereby ensuring that the difference in the number of disconnected individual cells between different parallel units is less than or equal to the disconnection difference setting value. Herein, the certain number refers to the difference between the sum of the number of individual cells in this parallel unit that meet the first disconnection condition and the second disconnection condition and the number of cells in the disconnection difference setting value.

[0019] Furthermore, each individual battery monitoring module is connected to the corresponding battery management unit via a one-wire interface circuit, and each battery management unit is connected to the battery cluster management unit via an isolation communication module.

[0020] With the above-described scheme, the series-parallel hybrid battery system of the present invention adopts a parallel-then-series approach. Each individual battery cell is connected in parallel with a separate individual battery monitoring module. These modules detect the output voltage, output current, and temperature of each individual battery cell. When the output voltage of any individual battery cell in a parallel unit exceeds a set voltage value, the corresponding monitoring module automatically disconnects this cell, preventing water loss, capacity decay, or even failure due to excessive voltage. Similarly, when the output current of any individual battery cell in a parallel unit exceeds a first set current value, the monitoring module automatically disconnects this cell, preventing excessive internal bias current or even parallel circulating current within the parallel unit, which could lead to battery overheating, capacity decay, or even safety issues. When any individual battery cell in a parallel unit meets a second disconnection condition, the corresponding battery management unit controls the monitoring module to disconnect this cell, preventing thermal runaway during charging and thus preventing thermal runaway of the entire parallel unit during charging. This ensures the battery system operates safely and stably. In this invention, the battery cluster management unit, in conjunction with each battery management unit, controls the active balancing between parallel units. The battery cluster management unit also manages the number of disconnected individual cells in each parallel unit, ensuring that the difference in the number of disconnected individual cells between different parallel units is less than or equal to the disconnection difference setting value. This eliminates the capacity bottleneck problem between the series-connected parallel units, enabling the battery system to operate stably and reliably.

[0021] Furthermore, each individual battery monitoring module is equipped with an electronic switch, which controls the on / off state of the charging and discharging circuits of each individual battery.

[0022] Furthermore, the electronic switch is a bidirectional switch, which can be turned on during both battery charging and discharging. Alternatively, the electronic switch can be a unidirectional switch, used only to control the charging process.

[0023] In summary, the series-parallel hybrid battery system of the present invention has the beneficial effects of controlling the bias current or parallel circulating current inside the parallel unit, eliminating the capacity bottleneck effect of each parallel unit connected in series, and ensuring the safety and stability of the entire battery system. Attached Figure Description

[0024] Figure 1 This is a circuit block diagram of an embodiment of the present invention;

[0025] Figure 2 for Figure 1 Circuit schematics of individual battery monitoring units (BCCUs);

[0026] Figure 3 The circuit diagram shows a series-parallel hybrid battery system in the prior art, which uses a series-then-parallel configuration.

[0027] Figure 4 The circuit diagram shows a hybrid series-parallel battery system in the prior art, which uses parallel connection followed by series connection.

[0028] Figure 5 This is a circuit diagram of the battery management system (BMU) in this invention. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0030] The terms "first," "second," etc., used in the specification and claims of this invention are used to distinguish different objects, not to describe a particular order. The terms "comprising" and "provided with," and any variations thereof, are intended to cover non-exclusive inclusion.

[0031] Figure 1 The illustration shows a specific embodiment of the present invention. In this embodiment, 220V AC power is converted to DC power via a switching power supply and then supplied to the base station equipment via a DC bus. The base station control host is also connected to the base station equipment via this DC bus. The series-parallel hybrid battery system of the present invention serves as the energy storage system for the base station equipment, providing power to the base station control host when needed. The battery cluster management unit (BCMU) of the series-parallel hybrid battery system of the present invention is located within the base station control host.

[0032] like Figure 1 As shown, the series-parallel hybrid battery system of the present invention includes four parallel units connected in series. Each parallel unit has ten individual batteries connected in parallel. Each individual battery is a 12V 64AH battery. The total voltage of the entire battery system is 48V, the total current is 100A, and the total capacity is 30.72 kWh. Based on the characteristics and working environment of the base station control host, if the negative terminal of the base station control host is grounded, it is prone to dust accumulation. Therefore, in this embodiment, the positive terminal of the base station control host is grounded.

[0033] according to Figure 1 The four parallel units are designated as the first parallel unit, the second parallel unit, the third parallel unit, and the fourth parallel unit from bottom to top.

[0034] Each parallel unit includes a battery management unit (BMU), 10 individual cells, and 10 individual cell monitoring modules (BCCU). The 10 individual cells in the first parallel unit are BT11, BT12, BT13, ..., and BT110; the 10 individual cells in the second parallel unit are BT21, BT22, BT23, ..., and BT210; the 10 individual cells in the third parallel unit are BT31, BT32, BT33, ..., and BT310; and the 10 individual cells in the fourth parallel unit are BT41, BT42, BT43, ..., and BT410.

[0035] In the same parallel unit, each individual battery monitoring module (BCCU) is connected to each individual battery cell in a one-to-one correspondence. The individual battery monitoring modules (BCCU) communicate with each other and with the corresponding battery management unit (BMU).

[0036] The battery management units (BMUs) of each parallel unit communicate with each other through the TX and RX interfaces and communicate with the battery cluster management unit (BCMU).

[0037] Each parallel unit's battery management unit (BMU) is equipped with an active balancing circuit, and the active balancing circuits of each parallel unit's battery management unit (BMU) are connected together through balancing buses EA and EB.

[0038] The parallel units are connected in series. The voltage across the first parallel unit is -48V to -36V, the voltage across the second parallel unit is -36V to -24V, the voltage across the third parallel unit is -24V to -12V, and the voltage across the fourth parallel unit is -12V to 0V.

[0039] The circuit structures of each parallel unit are the same; the following explanation will focus on the first parallel unit as an example.

[0040] In the first parallel unit, the positive terminal (B+) of each individual battery (BT11-BT110) is connected to the positive power terminal of each individual battery monitoring module (BCCU), and the positive terminal (B-) of each individual battery is connected to the negative power terminal of each individual battery monitoring module (BCCU). The individual battery monitoring modules (BCCU) communicate with each other and with the battery management unit (BMU) of the first parallel unit via DA interfaces. The ground terminals (P-) of each individual battery monitoring module (BCCU) and the battery management unit (BMU) of the first parallel unit are connected to the power supply terminal (-48V) of the base station control host.

[0041] The circuit structure of each individual battery monitoring module (BCCU) in each parallel unit is the same. The following explanation will be based on an example of an individual battery monitoring module (BCCU) in the first parallel unit.

[0042] like Figure 2 As shown, the single-cell battery monitoring module (BCCU) includes an MCU, a power output module, a voltage sampling circuit (resistors R13 and R14), a current sampling circuit (resistor RA1), a temperature sampling circuit (temperature sensor NTC), a switching circuit, and a communication module (one-wire communication module).

[0043] The input terminal of the power output module is connected to the positive terminal (B+) of the individual battery cell, and the output terminal of the power output module outputs a 3.3V voltage to provide operating power for the MCU. Voltage sampling circuits, current sampling circuits, and temperature sampling circuits are connected to the corresponding detection input terminals of the MCU. The switching circuit includes a drive circuit and electronic switches. The electronic switches are a bidirectional combination, specifically including MOSFETs U4 and U5. The input terminal of the drive circuit is connected to the control output terminal of the MCU, and the output terminal of the drive circuit is connected to the gates of MOSFETs U4 and U5, respectively. MOSFETs U4 and U5 are connected in reverse series in the charging and discharging circuit of the individual battery cell. The MCU communicates with the communication module, and the DA interface of the communication module is connected to the DA interface of the corresponding battery management unit for communication. The ground terminal (P-) of the individual battery monitoring module (BCCU) is connected to the ground terminal (P-) of the battery management unit (BMU) of the first parallel unit.

[0044] The circuit structure of the battery management unit (BMU) of each parallel unit is the same. Now, we will only take the battery management unit (BMU) of one of the parallel units as an example for explanation.

[0045] like Figure 5As shown, the Battery Management Unit (BMU) includes a regulated power supply module UM1, a voltage sampling circuit, an isolated communication module, a CPU, a one-line communication module, and an active balancing circuit. The input of the regulated power supply module UM1 is connected to the positive terminal (B+) of the individual battery cell, and its output is VCC, providing power to the CPU. The voltage sampling circuit consists of resistors R35 and R36. One end of resistor R35 is connected to the positive terminal (B+) of the individual battery cell, and the other end of resistor R35 is connected to one end of resistor R36 and then to the sampling input of the CPU. The other end of resistor R36 is grounded. The isolated communication module communicates with the Battery Cluster Management Unit (BCMU) via TX and RX interfaces. The isolated communication module, CPU, and one-line communication module communicate sequentially with each other. The DA interface of the one-line communication module communicates with the DA interfaces of the communication modules of the corresponding individual battery monitoring modules (BCCU) in the parallel unit.

[0046] In this invention, the active equalization circuit can be a commonly used existing active equalization circuit. In this embodiment, the active equalization circuit adopts the one disclosed in Chinese invention patent application CN110798149A. Figure 1 The self-excited push-pull oscillator circuit shown.

[0047] The power equalization control principle of the present invention is as follows: In each battery management unit (BMU), the CPU samples the voltage BVD of the corresponding parallel unit through the voltage sampling circuit, and communicates with the individual battery monitoring module (BCCU) in the corresponding parallel unit through the one-line communication module to summarize the voltage, current, temperature, capacity and other data of each individual battery. Then, the summarized data is sent to the battery cluster management unit (BCMU) through the isolation communication module. The Battery Cluster Management Unit (BCMU) compares the voltages of the four parallel units in real time. When the voltage difference between any two parallel units reaches the voltage imbalance setting value of 200mV set by the BCMU, the BCMU sends a start balancing command to each Battery Management Unit (BMU). The CPU in each BMU sets the output signal EPC to 0, turns on the field-effect transistor Q15, and also turns on diodes D4 and D5, driving the active balancing circuit to work. The output terminals of the active balancing circuit of each BMU (the two ends of the secondary coil of transformer T1) are connected together through the balancing bus EA and EB. The power transfer between the parallel units is carried out through the balancing bus EA and EB to achieve power balance between the parallel units.

[0048] In this invention, each individual battery monitoring module (BCCU) has the same first current setting value, the same voltage setting value, and the same first disconnection condition; each battery management unit (BMU) has the same second current setting value, the same second current duration setting value, the same first temperature setting value, the same first temperature duration setting value, the same second temperature setting value, and the same second disconnection condition. The first disconnection condition is that the voltage of the individual battery is higher than the voltage setting value and / or the current of the individual battery is higher than the first current setting value; the second disconnection condition is that the current of the individual battery is higher than the second current setting value and the duration exceeds the second current duration setting value, or / and the temperature of the individual battery is higher than the first temperature setting value and the duration exceeds the first temperature duration setting value, or / and the temperature of the individual battery is higher than the second temperature setting value. The battery cluster management unit (BCMU) has a disconnection difference setting value for each parallel unit.

[0049] In this embodiment, the first current setting is 20A, and the voltage setting is 15V. The first disconnection condition is one or a combination of two conditions: the current of a single battery cell is greater than 20A and the voltage of a single battery cell is greater than 15V. That is, a single battery cell may have one of these conditions or both of these conditions. As long as one of these conditions is met, the corresponding single battery cell monitoring module determines that the single battery cell meets the first disconnection condition.

[0050] In this embodiment, the second current setting is 15A, the second current duration setting is 10 minutes, the first temperature setting is 60℃, the first temperature duration setting is 10 minutes, and the second temperature setting is 80℃. The second disconnection condition is one or more combinations of the following three conditions: the current of a single battery cell is greater than 15A and the duration exceeds 10 minutes; the temperature of a single battery cell is higher than 60℃ and the duration exceeds 10 minutes; and the temperature of a single battery cell is higher than 80℃. That is, a single battery cell may have one, two, or even three of these conditions. As long as one of these conditions is met, the corresponding battery management unit determines that the single battery cell meets the second disconnection condition.

[0051] In this embodiment, the disconnection difference value for each parallel unit is set to 3.

[0052] In this invention, the single-cell monitoring module (BCCU) is used to detect the operating parameters of its corresponding single cell, such as voltage, current, temperature, and capacity, and to disconnect the charging and discharging circuit of the single cell when an abnormality occurs. Specifically:

[0053] The battery cell monitoring module (BCCU) monitors the voltage, current, temperature, capacity and other operating parameters of its corresponding battery cell in real time and uploads them to the corresponding battery management unit.

[0054] like Figure 2 As shown, when the individual battery is fault-free, the MCU outputs a switch control signal to the drive circuit, which in turn outputs a drive signal to either MOSFET U4 or U5. MOSFET U4 or U5 then conducts, connecting the charging and discharging circuit of the individual battery, allowing it to operate normally. MOSFETs U4 and U5 are respectively activated during the charging or discharging process, achieving bidirectional conduction.

[0055] When the MCU of the single cell monitoring module (BCCU) detects that the voltage of its corresponding single cell is higher than the voltage setting value of 15V, the MCU stops outputting the switch control signal to the drive circuit, and the drive circuit stops outputting the drive signal to the field effect transistors U4 and U5. Both field effect transistors U4 and U5 are turned off, disconnecting the charging and discharging circuit of this single cell (and at the same time disconnecting the single cell monitoring module). This can prevent the single cell from losing water, capacity decaying or even failing due to excessive voltage.

[0056] When the MCU of the single-cell monitoring module (BCCU) detects that the current of its corresponding single cell is higher than 20A, the MCU stops outputting the switch control signal to the drive circuit, and the drive circuit stops outputting the drive signal to the field-effect transistor U4 or U5. Both field-effect transistors U4 and U5 are turned off, disconnecting the charging and discharging circuit of this single cell (and at the same time disconnecting the monitoring module of this single cell). This can prevent the internal bias current of the corresponding parallel unit from being too large or even generating parallel circulating current, which would lead to battery heating, capacity decay, or even safety problems.

[0057] When the MCU of the single cell monitoring module (BCCU) detects that the voltage of its corresponding single cell is higher than the voltage setting value of 15V and the current is higher than 20A, the MCU stops outputting switch control signals to the drive circuit, and the drive circuit stops outputting drive signals to the field effect transistors U4 and U5. Both field effect transistors U4 and U5 are turned off, disconnecting the charging and discharging circuit of this single cell (and at the same time disconnecting the single cell monitoring module).

[0058] When the Battery Management Unit (BMU) detects that an individual cell in its corresponding parallel unit meets the second disconnection condition (one or more of the following three conditions: the cell current is greater than 15A and lasts for more than 10 minutes, the cell temperature is higher than 60°C and lasts for more than 10 minutes, or the cell temperature is higher than 80°C), the BMU sends a control command to the corresponding Cell Monitoring Unit (BCCU). The MCU of the BCCU stops outputting switch control signals to the drive circuit, and the drive circuit stops outputting drive signals to MOSFETs U4 and U5. MOSFETs U4 and U5 are both turned off, disconnecting the charging and discharging circuit of this cell, thereby preventing thermal runaway of this cell during charging, and thus preventing thermal runaway of the entire parallel unit during charging, allowing the battery system to operate safely and stably.

[0059] In this invention, in order to eliminate the capacity bottleneck problem among the parallel units connected in series and ensure the stable operation of the system, the Battery Cluster Management Unit (BCMU) manages the number of individual cells disconnected in each parallel unit. If the sum of the number of individual cells in a parallel unit that meet the first disconnection condition and the second disconnection condition exceeds the disconnection difference setting value (3) set by the Battery Cluster Management Unit (BCMU), then the Battery Cluster Management Unit controls other parallel units to disconnect a certain number of individual cells, so that the difference in the number of individual cells disconnected between different parallel units is less than or equal to the disconnection difference setting value (3).

[0060] During operation, the Battery Cluster Management Unit (BCMU) monitors the on / off status of all individual battery monitoring modules (BCCUs) in the entire battery system, and performs statistical analysis and control on the disconnection data of individual battery monitoring modules (BCCUs) within the same parallel unit. For example, taking the equalization current of the Battery Management Unit (BMU) as 30A, when all individual batteries in other parallel units are operating normally, a maximum of three individual battery monitoring modules (BCCUs) are allowed to disconnect within the same parallel unit. This controls the capacity deviation between parallel units, thereby eliminating the capacity bottleneck problem between series-connected parallel units and achieving an exponential reduction in system failures.

[0061] In this invention, a matrix-style strong equalization is adopted, which means equalizing the interconnection and interaction between the individual cell monitoring module (BCCU) and the battery management unit (BMU).

[0062] When the sum of the number of individual cells that meet the first disconnection condition and the second disconnection condition in a certain parallel unit does not exceed the disconnection difference setting value (3 cells), the battery management unit (BMU) corresponding to that parallel unit controls the corresponding individual cell monitoring module (BCCU) to disconnect the individual cells that meet the first disconnection condition and the individual cells that meet the second disconnection condition.

[0063] When all individual cells in other parallel units are working normally, and the number of disconnected individual cells in a certain parallel unit has reached the disconnection difference setting (3), if a new individual cell that meets the first or second disconnection condition is added to this parallel unit, the Battery Cluster Management Unit (BCMU) issues an equalization command to the Battery Management Unit (BMU) corresponding to the other parallel units. The BMUs corresponding to the other parallel units then control their respective parallel units to disconnect the same number of individual cells that meet the first or second disconnection condition before the newly added individual cells that meet the first or second disconnection condition in this parallel unit are allowed to disconnect. This ensures that the difference in the number of disconnected individual cells between different parallel units is less than or equal to the disconnection difference setting (3), thereby controlling the capacity deviation between parallel units and eliminating the capacity bottleneck problem between series-connected parallel units, achieving an exponential reduction in system failures.

[0064] Here's a concrete example: When all the individual cells in other parallel units are working normally, and the number of disconnected individual cells in a certain parallel unit has reached 3, if another individual cell that meets the first or second disconnection condition is added to this parallel unit, then there are a total of 4 faulty individual cells in this parallel unit that meet the first or second disconnection condition. The first 3 faulty individual cells have already been disconnected. At this time, the 4th faulty individual cell cannot be directly disconnected. Instead, the Battery Cluster Management Unit (BCMU) must issue an equalization command to the Battery Management Unit (BMU) corresponding to the other parallel units. The Battery Management Unit (BMU) corresponding to the other parallel units will then control the corresponding parallel units to disconnect one individual cell each before the 4th faulty individual cell in this parallel unit is allowed to be disconnected. This ensures that the difference in the number of disconnected individual cells between different parallel units is less than or equal to the disconnection difference setting value (3 cells).

[0065] When all individual cells in other parallel units are operating normally, and the sum of the number of individual cells in a certain parallel unit that meet the first and second disconnection conditions is greater than the disconnection difference setting (3), the Battery Cluster Management Unit (BCMU) issues an equalization command to the Battery Management Unit (BMU) corresponding to the other parallel units. The BMUs corresponding to the other parallel units then control their respective parallel units to disconnect a certain number of individual cells (here, the individual cells to be disconnected first are those with smaller capacity). Only then are the individual cells in this parallel unit that meet the first and second disconnection conditions allowed to disconnect, thus ensuring that the difference in the number of disconnected individual cells between different parallel units is less than or equal to the disconnection difference setting (3), thereby controlling the capacity deviation between each parallel unit and eliminating the capacity bottleneck problem between the series-connected parallel units, achieving an exponential reduction in system failures. Here, the certain number refers to the difference between the sum of the number of individual cells in this parallel unit that meet the first and second disconnection conditions and the number of cells that meet the disconnection difference setting.

[0066] Here's a concrete example: When all individual cells in other parallel units are working normally, and the sum of the number of faulty individual cells in a certain parallel unit that meet the first and second disconnection conditions is 4, the Battery Cluster Management Unit (BCMU) issues an equalization command to the Battery Management Unit (BMU) corresponding to the other parallel units. The BMUs of the other parallel units then control their respective parallel units to disconnect one individual cell at a time. Only then are the individual cells in this parallel unit that meet the first disconnection condition and the 4 faulty individual cells that meet the second disconnection condition allowed to disconnect, thus ensuring that the difference in the number of disconnected individual cells between different parallel units is less than or equal to the disconnection difference setting (3 cells).

[0067] In this way, when the number of faulty individual cells in a parallel unit increases, the battery cluster management unit (BCMU) can control the individual cell monitoring modules (BCCU) in other parallel units, thereby enabling the stable operation of the system with a smaller active balancing current (30A) to meet the larger total current (100A), or even more parallel cells and a larger total current, using a smaller active balancing current (30A).

[0068] For example, in a series-parallel hybrid battery system where the first battery is connected in parallel and the second in series, the capacity X of each individual battery is 12 * 64 = 768 Wh, the number N of parallel units connected in series is 4, the number P of individual batteries connected in parallel in each parallel unit is 10, and the total capacity C0 is 30.72 kWh. When the number M of faulty individual batteries in the same parallel unit is 4, since there are 4 faulty individual batteries in this parallel unit, only the remaining 6 individual batteries can be charged during charging. The capacity of this parallel unit is the sum of the capacities of these 6 individual batteries. Due to the capacity bottleneck effect, other parallel circuits connected in series can only be charged with the same capacity as the faulty parallel unit (or the parallel unit with the most faults).

[0069] If such as Figure 4 The traditional series-parallel hybrid battery system shown has the following existing total capacity C1:

[0070] C1=C0-(X*M*N)=30720-(768*4*4)=18432WH;

[0071] At this point, the parameter representing the health of the battery system, SOH1, is calculated as C1 / C0 = 18432 / 30720 = 60%. This means that the battery's SOH is far below the end of its lifespan, and the battery system is in an unhealthy state.

[0072] If the battery system of the present invention is used, the short-term effect of the capacity bottleneck is eliminated. When encountering the above situation, the total capacity C2 of the battery system using the battery system of the present invention is:

[0073] C2=C0-X*M=30720-768*4=27648WH;

[0074] At this point, the parameter representing the health of the battery system, SOH2=C2 / C0=27648 / 30720=90%, indicates that the battery system is in good health.

[0075] In this invention, parameters such as the first current setting value, voltage setting value, second current setting value, second current duration setting value, first temperature setting value, first temperature duration setting value, second temperature setting value, disconnection difference setting value, and voltage imbalance setting value can all be set to appropriate parameter values ​​according to the needs of the actual application scenario.

[0076] In this invention, the electronic switches in each of the individual battery monitoring modules can also be unidirectional electronic switches used only to control the charging process.

[0077] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent application and the contents of the specification of the present invention should still fall within the scope of the patent of the present invention.

Claims

1. A series-parallel hybrid battery system, comprising multiple parallel units connected in series, each of the parallel units having multiple individual cells connected in parallel; characterized in that: In each of the parallel units, each individual battery is connected to an individual battery monitoring module, and each parallel unit is equipped with a battery management unit. The individual battery monitoring modules in the same parallel unit are interconnected and communicate with the corresponding battery management unit. Each battery management unit is equipped with an active balancing circuit, and the active balancing circuits of each battery management unit are connected together through a balancing bus. The battery management units are interconnected and communicate with each other and with the battery cluster management unit. Each individual battery monitoring module is used to detect the voltage, current, and temperature of the corresponding individual battery. Each individual battery monitoring module has the same first current setting value, the same voltage setting value, and the same first disconnection condition. Each battery management unit has the same second current setting value, the same second current duration setting value, the same first temperature setting value, the same first temperature duration setting value, the same second temperature setting value, and the same second disconnection condition. The first disconnection condition is that the voltage of the individual battery is higher than the voltage setting value and / or the current of the individual battery is higher than the first current setting value. The second disconnection condition is that the current of the individual battery is higher than the second current setting value and the duration exceeds the second current duration setting value, or / and the temperature of the individual battery is higher than the first temperature setting value and the duration exceeds the first temperature duration setting value, or / and the temperature of the individual battery is higher than the second temperature setting value. When an individual battery meets the first disconnection condition, its corresponding individual battery monitoring module automatically disconnects the individual battery. When a single cell meets the second disconnection condition, the corresponding battery management unit controls the corresponding single cell monitoring module to disconnect the single cell. The battery cluster management unit compares the voltages of each parallel unit. When the voltage difference between any two parallel units reaches the voltage imbalance set value, it sends a start balancing command to each battery management unit to control its active balancing circuit to start working. The power is transferred between them through the balancing bus to achieve power balancing between each parallel unit. The battery cluster management unit centrally manages the number of individual batteries disconnected in each of the parallel units. If the sum of the number of individual batteries in a parallel unit that meet the first disconnection condition and the second disconnection condition exceeds the disconnection difference setting value set by the battery cluster management unit, then the battery cluster management unit controls other parallel units to disconnect a certain number of individual batteries, so that the difference in the number of individual batteries disconnected between different parallel units is less than or equal to the disconnection difference setting value.

2. The series-parallel hybrid battery system according to claim 1, characterized in that: Each of the individual battery monitoring modules is equipped with an MCU, a voltage sampling circuit, a current sampling circuit, a temperature sampling circuit, a switching circuit, and a communication module. The voltage sampling circuit, the current sampling circuit, and the temperature sampling circuit are respectively connected to the corresponding detection input terminals of the MCU. The switching circuit includes a drive circuit and an electronic switch. The input terminal of the drive circuit is connected to the control output terminal of the MCU. The electronic switch is connected in series in the charging and discharging circuit of the corresponding individual battery. The output terminal of the drive circuit is connected to the control terminal of the electronic switch. The MCU communicates with the corresponding battery management unit through the communication module.

3. A series-parallel hybrid battery system according to claim 2, characterized in that: The electronic switch is a unidirectional switch, or the electronic switch is a combination of bidirectional electronic switches.

4. A series-parallel hybrid battery system according to claim 2, characterized in that: When the MCU detects that its corresponding single battery cell meets the first disconnection condition, the MCU outputs a control signal to the drive circuit, and the drive circuit drives the electronic switch to disconnect the charging and discharging circuit of the corresponding single battery cell. When a single cell meets the second disconnection condition, the corresponding battery management unit determines that the single cell has thermal runaway. The battery management unit then outputs a control command to the corresponding single cell monitoring module. The MCU of the corresponding single cell monitoring module outputs a control signal to the drive circuit, which drives the electronic switch to disconnect the charging and discharging circuit of the corresponding single cell.

5. A series-parallel hybrid battery system according to claim 1, characterized in that: When the sum of the number of individual cells in a parallel unit that meet the first disconnection condition and the number of individual cells that meet the second disconnection condition does not exceed the disconnection difference setting value, the battery management unit corresponding to the parallel unit controls the corresponding individual cell monitoring module to disconnect the individual cells that meet the first disconnection condition and the individual cells that meet the second disconnection condition. When other parallel units are working normally, if the number of disconnected individual cells in a certain parallel unit has reached the disconnection difference setting value, and a new individual cell that meets the first or second disconnection condition is added to this parallel unit, then the battery cluster management unit issues an equalization command to the battery management unit corresponding to the other parallel units. The battery management unit corresponding to the other parallel units controls the corresponding parallel units to first disconnect the same number of individual cells that meet the first or second disconnection condition. Only after this number of individual cells that meet the first or second disconnection condition are disconnected in this parallel unit can the new individual cells that meet the first or second disconnection condition be allowed to disconnect, thereby ensuring that the difference in the number of disconnected individual cells between different parallel units is less than or equal to the disconnection difference setting value. When other parallel units are operating normally, if the sum of the number of individual cells in a certain parallel unit that meet the first disconnection condition and the second disconnection condition is greater than the disconnection difference setting value, then the battery cluster management unit issues an equalization command to the battery management units corresponding to the other parallel units. The battery management units corresponding to the other parallel units then control their respective parallel units to disconnect a certain number of individual cells first. Only then are the individual cells in this parallel unit that meet the first disconnection condition and the second disconnection condition allowed to disconnect, thereby ensuring that the difference in the number of disconnected individual cells between different parallel units is less than or equal to the disconnection difference setting value. Herein, the certain number refers to the difference between the sum of the number of individual cells in this parallel unit that meet the first disconnection condition and the second disconnection condition and the number of cells in the disconnection difference setting value.

6. A series-parallel hybrid battery system according to claim 2, characterized in that: Each individual battery monitoring module communicates with the corresponding battery management unit via a one-wire interface circuit, and each battery management unit communicates with the battery cluster management unit via an isolation communication module.

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