Battery active equalization system and active equalization method

Abstract

The invention provides a battery active equalization system and an active equalization method. The system comprises a first DCDC module, a second DCDC module, a high-voltage battery pack, a low-voltage battery pack and an equalization circuit, the low-voltage battery pack is connected with the input end of the second DCDC module, the output end of the second DCDC module is connected with the input end of the equalization circuit, the output end of the equalization circuit is connected with the high-voltage battery pack, the high-voltage battery pack is connected with the input end of the first DCDC module, and the output end of the first DCDC module is connected with the input ends of the low-voltage battery pack and the second DCDC module; when the electric quantity of the low-voltage battery pack is sufficient, the low-voltage battery pack equalizes the high-voltage battery pack through the first equalization loop, and when the electric quantity of the low-voltage battery pack is insufficient and the battery active equalization system is powered on, the first DCDC module switches the output voltage of the high-voltage battery pack into the receiving voltage range of the second DCDC module. And the high-voltage battery pack is equalized through the second equalization loop. According to the invention, the battery equalization efficiency and performance can be optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of battery management, and in particular to a battery active equalization system and an active equalization method. Background Art

[0002] The voltage of a single lithium-ion battery is relatively low. In actual use, several single batteries need to be combined so that the battery pack can meet the corresponding voltage and power requirements. However, due to the manufacturing differences of individual batteries during the production and processing process and the unique chemical properties of lithium batteries themselves, there are differences in the initial capacity, internal resistance, voltage, etc. of single lithium batteries in the same batch. When lithium batteries are used in groups, there is a defect that the parameters of single lithium batteries are inconsistent, making it difficult to achieve the goal of completely balanced charging and discharging, and the battery is prone to overcharging or over-discharging. As the number of charging cycles increases, the unbalanced charge and discharge state of the battery pack will eventually lead to a decrease in the capacity performance of the battery pack and a decrease in its service life, and then the entire battery pack will not work properly or even be scrapped. In order to avoid overcharging and over-discharging and extend the service life of the battery pack, it is necessary to balance the energy of the battery pack to improve the consistency and energy utilization of the battery pack.

[0003] In the current automotive BMS field, battery balancing can be divided into two categories according to the form of energy conversion. The main balancing methods are active balancing (energy transfer form) and passive balancing (energy consumption form). The balancing principle of passive balancing is to release the excess power of the battery cells to the resistor. This method is simple to operate and has been implemented, but the excess energy of the battery cannot be utilized, and the temperature of the battery pack will rise to a certain extent. In addition, the balancing current is small, generally only about 100mA, and the balancing effect is very limited for vehicle-mounted power battery packs with a current of more than several hundred amperes. Summary of the invention

[0004] The present invention aims to provide a battery active balancing system and an active balancing method to solve the above technical problems and optimize the efficiency and performance of battery balancing.

[0005] In order to solve the above technical problems, the present invention provides a battery active balancing system, including: a first DCDC module, a second DCDC module, a high-voltage battery pack, a low-voltage battery pack and a balancing circuit;

[0006] The low-voltage battery pack is connected to the input end of the second DCDC module, the output end of the second DCDC module is connected to the input end of the balancing circuit, the output end of the balancing circuit is connected to the high-voltage battery pack, the high-voltage battery pack is connected to the input end of the first DCDC module, and the output end of the first DCDC module is connected to the low-voltage battery pack and the input end of the second DCDC module;

[0007] When the low-voltage battery pack is sufficiently charged, the low-voltage battery pack balances the high-voltage battery pack through a first balancing circuit consisting of the low-voltage battery pack, the second DCDC module, the balancing circuit and the high-voltage battery pack; when the low-voltage battery pack is insufficiently charged, after the battery active balancing system is powered on, the first DCDC module switches the output voltage of the high-voltage battery pack to within the receiving voltage range of the second DCDC module, and the high-voltage battery pack balances the high-voltage battery pack through a second balancing circuit consisting of the high-voltage battery pack, the first DCDC module, the second DCDC module and the balancing circuit.

[0008] In the above scheme, an active balancing method is adopted. Through the cooperation of the first DCDC module and the second DCDC module, the system can effectively transfer the power of the high-voltage battery pack to the low-voltage battery pack, avoiding the waste of excess power consumed by the resistor in the passive balancing method, and improving the energy utilization efficiency. Compared with the passive balancing method, the temperature rise of the battery pack can be significantly reduced, which helps to keep the battery running at a suitable operating temperature and extend the battery life. The output voltage of the high-voltage battery pack is switched to the receiving voltage range of the second DCDC module through the first DCDC module, ensuring that the energy of the high-voltage battery pack can be effectively transmitted to the low-voltage battery pack and the balancing circuit, enhancing the adaptability and stability of the system. When the low-voltage battery pack is fully charged or insufficiently charged, different balancing strategies are adopted to ensure efficient battery balancing under various working conditions. Through the two-way energy flow of the two DCDC modules and the balancing circuit, the energy balance between the batteries can be achieved more effectively, avoiding the problem of small balancing current and limited effect in the passive balancing method.

[0009] In one implementation, the battery active balancing system includes a lithium battery pack,

[0010] The lithium battery pack includes n single cells connected in series;

[0011] m single cells connected in series are selected to construct a low-voltage battery pack, and a high-voltage battery pack is constructed based on the remaining (nm) single cells connected in series, where n and m are both positive integers greater than 1 and the value of (nm) is greater than m.

[0012] In one implementation, the battery active balancing system further includes a power distribution module.

[0013] The input end of the power distribution module is connected to the high-voltage battery pack, and the output end is connected to the input end of the first DCDC module; wherein the first DCDC module is used to convert the output voltage of the power distribution module into a receiving voltage range of the second DCDC module.

[0014] In one implementation, the high-voltage battery pack includes a plurality of single cells, and the balancing circuit includes a plurality of balancing switches.

[0015] The positive electrode of each single cell is connected to a first end of a balancing switch;

[0016] The second end of the balancing switch is connected to the output end of the second DCDC module.

[0017] In one implementation, the battery active balancing system further includes a master control unit and a slave control unit, and the high-voltage battery pack includes a plurality of single cells.

[0018] The slave control unit is used to collect the cell working data of each single cell in the high-voltage battery pack and send it to the master control unit; wherein the cell working data includes the single cell voltage value and the cell temperature;

[0019] The master control unit makes a battery balancing judgment based on the received battery cell working data, and sends a battery balancing control instruction to the slave control unit when the high-voltage battery pack needs to be balanced.

[0020] The slave control unit is also used to switch the working state of the equalization circuit in the high-voltage battery pack according to the received battery equalization control instruction.

[0021] In one implementation, the master control unit performs battery balancing judgment based on the received battery cell working data, and sends a battery balancing control instruction to the slave control unit when the high-voltage battery pack needs to be balanced, specifically including:

[0022] Obtain the maximum single cell voltage value in the battery cell working data, compare the maximum single cell voltage value with the remaining single cell voltage values, and when the difference between the maximum single cell voltage value and any single cell voltage value exceeds a first preset voltage threshold, control the main control unit to send a battery balancing control instruction to the slave control unit so that the slave control unit performs a battery balancing operation on the high-voltage battery pack.

[0023] In one implementation, the main control unit performs battery balancing judgment based on the received battery cell working data, further comprising:

[0024] When the cell temperature in the cell working data exceeds a preset threshold, it is determined that the temperature of the high-voltage battery pack is abnormal, and the main control unit is controlled to send a battery balancing interruption instruction to the slave control unit, so that the slave control unit interrupts the battery balancing operation.

[0025] In one implementation, the battery active balancing system further includes:

[0026] When the voltage value of a single cell in the low-voltage battery pack is lower than the second preset voltage threshold, the control main control unit sends a high-voltage instruction to the slave control unit, so that the high-voltage battery pack replenishes power to the single cell in the low-voltage battery pack through the first DCDC module.

[0027] In a second aspect, the present application further provides an active balancing method, which is applicable to the above battery active balancing system, comprising:

[0028] Step 1: collect the cell working data of each single cell in the high-voltage battery pack in real time, and make a battery balancing judgment based on the cell working data. When it is determined that the high-voltage battery pack needs to be balanced, control the main control unit to send a battery balancing control instruction to the slave control unit, so that the slave control unit switches the working state of the balancing switch in the high-voltage battery pack; wherein the high-voltage battery pack includes a plurality of single cells;

[0029] Step 2, control the second DCDC module to replenish power to the single cells in the high-voltage battery pack based on the turned-on balancing switch; wherein the second DCDC module is connected to the power distribution module through the first DCDC module, and the first DCDC module is used to convert the output voltage of the power distribution module to within the receiving voltage range of the second DCDC module.

[0030] In one implementation, the active balancing method further includes:

[0031] Real-time detection of the voltage value of each single cell in the low-voltage battery pack;

[0032] When there is a first single cell in the low-voltage battery pack whose voltage value is lower than a preset voltage threshold, if the high-voltage battery pack meets the preset charging condition, the high-voltage battery pack is controlled to charge the first single cell; wherein the preset charging condition is that the high-voltage battery pack is in normal working state and has surplus power. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A system structure block diagram of a battery active balancing system provided in one embodiment of the present invention;

[0034] Figure 2 A schematic diagram of the connection relationship of a battery active balancing system provided in one embodiment of the present invention;

[0035] Figure 3 A schematic diagram of the structure of a DCDC module provided in one embodiment of the present invention;

[0036] Figure 4 The figure is a flow chart of an active balancing method provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0037] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0038] The terms "first" and "second" and the like in the specification, claims and drawings of this application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0039] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0040] First, some terms in this application are explained to facilitate understanding by those skilled in the art.

[0041] (1) Electrical isolation: refers to the use of physical isolation measures in circuits or equipment to prevent current or voltage from being transmitted between different parts. This isolation can be achieved through insulating materials, air gaps, or electrical isolation devices (such as isolation transformers, optocouplers, etc.). The main purpose of electrical isolation is to improve the safety and reliability of the circuit, prevent electric shock, reduce interference, and protect the electronic devices in the circuit from the influence of the external environment.

[0042] (2) Cell: A cell is the basic unit of a battery pack, usually a single battery cell in a lithium-ion battery. In electric vehicles or other power systems, a battery pack consists of many cells connected in series or in parallel to provide the required voltage and capacity. Each cell has its own electrochemical characteristics and voltage range, which need to be balanced and managed during the charge and discharge process to ensure the performance, safety and life of the entire battery pack.

[0043] (3) DCDC module: refers to a direct current to direct current converter, a device used in electronic circuits to convert one DC voltage into another DC voltage. This module is widely used in various electronic devices and systems, including power management systems, communication equipment, electric vehicles, and integrated circuits.

[0044] Example 1

[0045] See also Figure 1 , Figure 1The system structure block diagram of a battery active balancing system provided in an embodiment of the present invention. The embodiment of the present invention provides a battery active balancing system, including: a first DCDC module, a second DCDC module, a high-voltage battery pack, a low-voltage battery pack and a balancing circuit;

[0046] The low-voltage battery pack is connected to the input end of the second DCDC module, the output end of the second DCDC module is connected to the input end of the balancing circuit, and the output end of the balancing circuit is connected to the high-voltage battery pack. When the low-voltage battery pack is fully charged, the low-voltage battery pack balances the high-voltage battery pack through the second DCDC module and the balancing circuit.

[0047] The high-voltage battery pack is connected to the input end of the first DCDC module, and the output end of the first DCDC module is connected to the low-voltage battery pack and the input end of the second DCDC module. When the low-voltage battery pack is low on power and the integrated battery active balancing system is powered on, the first DCDC module switches the output voltage of the high-voltage battery pack to within the receiving voltage range of the second DCDC module, and balances the high-voltage battery pack through the second DCDC module.

[0048] In an embodiment of the present invention, the low-voltage battery pack is connected to the input end of the equalization circuit through the second DCDC module, and the output end of the equalization circuit is connected to the high-voltage battery pack. When the low-voltage battery pack has sufficient power (for example, the voltage of the low-voltage battery pack is higher than a certain threshold), the system allows the equalization operation to start. The second DCDC module converts the voltage of the low-voltage battery pack to an input range suitable for the equalization circuit. This process ensures that the output voltage of the low-voltage battery pack can be effectively input into the equalization circuit. The equalization circuit receives power from the low-voltage battery pack and transfers excess power from the low-voltage battery pack to the high-voltage battery pack by adjusting the current. This process can achieve effective energy transfer through switches, converters or other circuit designs. After the high-voltage battery pack receives the energy transferred by the low-voltage battery pack, the power in the battery pack is balanced. This process can reduce the power difference of the battery cells in the high-voltage battery pack, thereby improving the overall performance. The high-voltage battery pack is connected to the low-voltage battery pack and the input end of the second DCDC module through the first DCDC module. When the system is powered on, the first DCDC module converts the output voltage of the high-voltage battery pack to a receiving voltage range suitable for the second DCDC module. This process ensures that the voltage of the high-voltage battery pack can be effectively adjusted to the required range of the low-voltage battery pack. The second DCDC module receives power from the high-voltage battery pack and converts it into a voltage and current suitable for the low-voltage battery pack. Through this process, energy is transferred from the high-voltage battery pack to the low-voltage battery pack. The low-voltage battery pack receives power from the high-voltage battery pack to help replenish its insufficient power. This energy transfer helps to balance the power differences within the battery pack. An integrated battery active balancing system provided by an embodiment of the present invention realizes bidirectional energy transfer between the high-voltage battery pack and the low-voltage battery pack by rationally utilizing the DCDC module and the balancing circuit, thereby improving the overall performance and service life of the battery pack.

[0049] In one embodiment, the integrated battery active balancing system includes a lithium battery pack, which includes n single cells connected in series; m single cells connected in series are selected to construct a low-voltage battery pack, and a high-voltage battery pack is constructed based on the remaining (nm) single cells connected in series, where n and m are both positive integers greater than 1 and the value of (nm) is greater than m.

[0050] In an embodiment of the present invention, a high-voltage battery pack and a low-voltage battery pack are integrated into a lithium battery pack, and a small number of single cells connected in series are selected from a number of single cells connected in series in the lithium battery pack as a low-voltage battery pack, and the remaining single cells connected in series are used as a high-voltage battery pack. Voltage isolation is performed between the high-voltage battery pack and the low-voltage battery pack. The electrical isolation between the high-voltage battery pack and the low-voltage battery pack helps to improve the safety of the system and avoid the direct impact of the power of the high-voltage battery pack on the low-voltage battery pack. Exemplarily, when there are n lithium-ion cells connected in series in the lithium battery pack, four lithium-ion cells B1, B2, B3, and B4 connected in series can be selected to form a low-voltage battery pack, that is, a low-voltage battery pack. The remaining (n-4) lithium-ion cells B4...Bn connected in series form a high-voltage battery pack, that is, a high-voltage battery pack.

[0051] In one embodiment, the integrated battery active balancing system also includes a power distribution module, the input end of the power distribution module is connected to the high-voltage battery pack, and the output end is connected to the input end of the first DCDC module; wherein the first DCDC module is used to convert the output voltage of the power distribution module to within the receiving voltage range of the second DCDC module.

[0052] In the embodiment of the present invention, a high-voltage distribution box is selected as the distribution module. Considering that the high-voltage battery pack is directly connected to the high-voltage distribution box, the high-voltage power can be transmitted to the whole vehicle system through the high-voltage battery pack. The BMS system needs to accurately monitor and manage the battery status, including the voltage, temperature and other parameters of the single battery. Low-voltage operation is safer and can provide more accurate sensor measurement results. Figure 2 , Figure 2A schematic diagram of the connection relationship of a battery active equalization system provided in one embodiment of the present invention. Specifically, the positive input interface of the input end of the high-voltage distribution box is connected to the positive electrode of the first single cell in the high-voltage battery pack through a control switch, and the negative input interface of the input end of the high-voltage distribution box is connected to the negative electrode of the last single cell in the high-voltage battery pack through a control switch. The first DCDC module converts the high voltage output by the high-voltage distribution box into a low-voltage (12V or 24V) direct current to power the low-voltage battery pack and the second DCDC module, so the low-voltage battery pack can be used to power the BMS system at a low voltage. Through low-voltage power supply, the BMS system can operate independently of the high-voltage battery pack, so that when the high-voltage system fails or loses power, it can continue to monitor and protect the battery pack. In electric vehicles, the whole vehicle system and the BMS system use high-voltage and low-voltage power supply respectively to maximize the performance and efficiency of the whole vehicle, while ensuring the safe management and protection of the battery pack. This division of labor enables the entire electric vehicle system to achieve the best balance and effect in providing power and maintaining battery life. In the embodiment of the present invention, the connection relationship between the two battery packs and the high-voltage distribution box and the two DCDC modules is set so that a high-voltage battery pack with high voltage and a low-voltage battery pack with low voltage can be integrated in one battery pack. The high-voltage battery pack is directly connected to the high-voltage distribution box, and the high-voltage power distribution box is used to distribute and manage the high-voltage power.

[0053] In one embodiment, the high-voltage battery pack includes multiple single cells, the balancing circuit includes a plurality of balancing switches, the positive electrode of each single cell is connected to the first end of a balancing switch; the second end of the balancing switch is connected to the output end of the second DCDC module.

[0054] In an embodiment of the present invention, a high-voltage battery pack includes a plurality of single cells, and a corresponding balancing circuit is also provided with a plurality of balancing switches. Specifically, a balancing switch is provided between each single cell in the high-voltage battery pack and the loop of the second DCDC module, and one end of each balancing switch is connected to the positive electrode of the single cell, and the other end is connected to the output end of the second DCDC module. Through these balancing switches, the power can be selectively transferred from the single cell of the high-voltage battery pack to the low-voltage battery pack, or reversely operated. This control method allows each single cell to be accurately balanced to ensure the balance of power of the entire battery pack. Based on the above connection relationship, when the balancing switch is closed, the current can flow from the single cell to the second DCDC module. The balancing switch controls whether the power of the single cell flows to the second DCDC module, thereby achieving the balance of the high-voltage battery pack. Further, in an embodiment of the present invention, the input end of the second DCDC module is also connected to the output end of the first DCDC module. Through the connection between the first DCDC module and the second DCDC module, it is ensured that the battery pack can obtain an appropriate voltage for power regulation.

[0055] See also Figure 3 , Figure 3 It is a structural schematic diagram of a DCDC module provided in one embodiment of the present invention. The DCDC module provided in the embodiment of the present invention includes the following structures: voltage detection (input side), noise filter (input side), voltage converter, noise filter (output side), voltage detection (output side), DC / DC conversion circuit and communication circuit. Among them, the voltage detection (input side) is used to measure the input voltage from the lithium-ion battery; the noise filter (input side) removes noise by using capacitors and coils; the voltage conversion circuit converts the voltage through switches such as insulating transformers and FETs; the noise filter (output side) uses capacitors and coils to remove noise; the voltage detection (output side) is used to measure the output voltage; the control circuit is used to control the conversion circuit; the DC / DC converter is used to supply power to the control circuit; the communication circuit is a communication circuit with the outside. The above structure is only an explanation of a feasible embodiment of the DCDC module in the embodiment of the present invention, and is not used to limit the specific structure of the DCDC module in the embodiment of the present invention.

[0056] See also Figure 2 , Figure 2 The present invention is a schematic diagram of the connection relationship of a battery active balancing system provided in an embodiment of the present invention. In the embodiment of the present invention, after the first input end of the first DCDC module is connected to the output end of the power distribution module, the system further includes: the second input end of the first DCDC module is connected to the low-voltage battery pack; wherein the positive input pin of the second input end of the first DCDC module is connected to the positive electrode of the first single cell in the low-voltage battery pack, and the negative input pin of the second input end of the first DCDC module is connected to the negative electrode of the last single cell in the low-voltage battery pack.

[0057] In an embodiment of the present invention, the output voltage of the power distribution module is converted by the first DCDC module. The function of the first DCDC module is to convert the voltage output by the power distribution module into a voltage range suitable for the low-voltage battery pack. This is because the power distribution module and the low-voltage battery pack may operate at different voltage levels, and the first DCDC module can adjust the voltage to ensure that the voltage requirements of the battery pack are met. The output end of the first DCDC module is connected to the low-voltage battery pack to ensure that the converted power can be effectively transmitted and stored in the low-voltage battery pack. This ensures that the low-voltage battery pack can receive the correct amount of power from the power distribution module and supports the operation and power management of the low-voltage battery pack. Connecting the output end of the power distribution module to the first DCDC module can achieve a balanced power supply in the entire system. In particular, when the low-voltage battery pack is fully charged, the power of the low-voltage battery pack can be used preferentially to reduce the burden on the high-voltage battery pack and help extend the service life of the battery.

[0058] In one embodiment, the integrated battery active balancing system also includes a master control unit and a slave control unit, specifically: the slave control unit is used to collect the cell working data of each single cell in the high-voltage battery pack and send it to the master control unit; wherein the cell working data includes the single cell voltage value and the cell temperature; the master control unit performs battery balancing judgment based on the received cell working data, and when the first battery group high-voltage battery group needs to perform battery balancing, sends a battery balancing control instruction to the slave control unit; the slave control unit is also used to switch the working state of the balancing circuit in the high-voltage battery pack according to the received battery balancing control instruction, so that the second DCDC module can replenish the single cells in the high-voltage battery pack.

[0059] The master control unit is the core of the BMS system, usually a circuit board that integrates data processing, strategy formulation and overall control functions. It is responsible for monitoring, managing and controlling the entire battery system; receiving battery status data sent by the slave control unit, analyzing and processing; formulating corresponding management strategies according to the battery status, such as charge and discharge control, thermal management, etc. Data is exchanged with external devices (such as vehicle control systems) through communication interfaces. The slave control unit is an auxiliary module distributed inside the battery pack, usually directly connected to the single battery. It is used to collect battery parameters, such as voltage, current, temperature, etc.; send the collected battery status data to the master control unit; and execute the instructions of the master control unit, such as performing balancing operations on the single battery. In an embodiment of the present invention, the slave control unit collects the working data of the battery cell through sensors directly connected to the single battery. These sensors include voltage sensors, current sensors, and temperature sensors. The voltage sensor is used to measure the voltage value of the single battery, the current sensor is used to monitor the charge and discharge current of the battery, and the temperature sensor is used to detect the working temperature of the battery. These sensors transmit the collected data to the slave control unit in real time, and the slave control unit then sends these data to the master control unit for further processing and analysis. The slave control unit performs corresponding balancing actions according to the battery balancing control instructions sent by the master control unit and reports the actual balancing status of the high-voltage battery pack to the master control unit.

[0060] In an embodiment of the present invention, a master control unit and a slave control unit are further provided in the integrated battery active balancing system. The slave control unit collects the voltage value and temperature data of each single cell in the high-voltage battery pack, and these data are important bases for battery balancing. The working state of the cell is monitored in real time to ensure that the voltage imbalance and temperature abnormality in the battery pack can be discovered in time. The slave control unit sends the collected data to the master control unit, and the master control unit makes a battery balancing judgment based on the received cell working data. If it is detected that there is a power imbalance in the cells in the battery pack (for example, the voltage of some cells is lower than that of other cells), the master control unit will decide whether battery balancing is required. When battery balancing is required, the master control unit will send a battery balancing control instruction to the slave control unit. This instruction includes how to switch the working state of the balancing circuit so as to recharge the battery pack. After receiving the battery balancing control instruction, the slave control unit will switch the working state of the balancing circuit so that the second DCDC module can recharge the battery pack. During the balancing process, the second DCDC module extracts power from the battery pack and replenishes it to the single cell with insufficient power to achieve power balance of the entire battery pack. By real-time monitoring of battery cell data and active balancing control, the system can maintain the power balance of each single battery cell in the battery pack. This helps to improve the overall performance of the battery pack, extend battery life, and avoid over-discharge or over-charging problems caused by unbalanced power.

[0061] In one embodiment, the battery active balancing system also includes a master control unit and a slave control unit. The high-voltage battery pack includes multiple single cells. The slave control unit is used to collect the cell working data of each single cell in the high-voltage battery pack and send it to the master control unit; wherein the cell working data includes the single cell voltage value and the cell temperature; the master control unit performs battery balancing judgment based on the received cell working data, and when the high-voltage battery pack needs to be balanced, sends a battery balancing control instruction to the slave control unit; the slave control unit is also used to switch the working state of the balancing circuit in the high-voltage battery pack according to the received battery balancing control instruction.

[0062] In an embodiment of the present invention, a plurality of single cells are included in the high-voltage battery pack, and the voltage difference of the single cells in the high-voltage battery pack is used as a criterion for judging whether battery balancing is turned on. The input end of the slave control unit is connected to the output end of the balancing circuit, that is, the second end of each balancing switch is connected to the output end of the second DCDC module, and is also connected to the input end of the slave control unit, so that the slave control unit can collect the cell balance and working data of each single cell in the high-voltage battery pack. If the voltage difference of the single cells in the battery pack exceeds a preset threshold (such as 20mV), it is necessary to turn on battery balancing, and control the main control unit to send a battery balancing control instruction to the slave control unit. Preferably, the balancing demand during charging, battery health management during discharging, battery capacity and health status monitoring, and battery management strategy setting can also be used as a criterion for judging whether battery balancing is turned on. When the high-voltage battery pack needs to be balanced, the slave control unit switches the working state of the balancing circuit in the high-voltage battery pack according to the received battery balancing instruction, and realizes battery balancing by turning on different balancing loops. Specifically, when the low-voltage battery pack is fully charged, after receiving the battery balancing control instruction from the control unit, the first balancing circuit (composed of the low-voltage battery pack, the second DCDC module, the balancing circuit and the high-voltage battery pack) is enabled. Through this circuit, the energy of the low-voltage battery pack can be transferred to the high-voltage battery pack to achieve battery balancing. When the low-voltage battery pack is insufficiently charged, after receiving the battery balancing control instruction from the control unit, the second balancing circuit (composed of the high-voltage battery pack, the first DCDC module, the second DCDC module and the balancing circuit) is enabled. Through this circuit, the energy of the high-voltage battery pack can be transferred to the balancing circuit to achieve battery balancing.

[0063] In one embodiment, the main control unit performs battery balancing judgment based on the received battery cell working data, and sends a battery balancing control instruction to the slave control unit when the high-voltage battery pack needs to be battery balancing, specifically including: obtaining the maximum single cell voltage value in the battery cell working data, comparing the maximum single cell voltage value with the remaining single cell voltage values, and when the difference between the maximum single cell voltage value and any single cell voltage value exceeds a first preset voltage threshold, controlling the main control unit to send a battery balancing control instruction to the slave control unit so that the slave control unit performs a battery balancing operation on the high-voltage battery pack.

[0064] In an embodiment of the present invention, when the low-voltage battery pack is fully charged, the slave control unit is connected to the first balancing loop. According to the specific situation of the collected battery cell working data, the output parameters (voltage and current) of the two DCDC modules are controlled to ensure that energy can be effectively transferred. Electric energy is transferred from the battery cells with higher voltage to the battery cells with lower voltage to achieve balancing. The specific method and path of energy transfer can be selected according to the voltage difference of the battery cell. According to the actual monitored voltage difference, the balancing current size is dynamically adjusted to ensure the safety of the entire balancing process, and the duration of balancing is set.

[0065] Preferably, in one embodiment, the main control unit performs battery balancing judgment based on the received battery cell working data, and also includes: when the battery cell temperature in the battery cell working data exceeds a preset threshold, it is determined that the temperature of the high-voltage battery pack is abnormal, and the main control unit is controlled to send a battery balancing interrupt instruction to the slave control unit, so that the slave control unit interrupts the battery balancing operation.

[0066] In the embodiment of the present invention, when the battery pack exceeds the normal operating temperature range, the battery balancing operation is suspended to protect the safety and stability of the battery. Further, when the battery active balancing system enters a dormant state or detects that the voltage difference of the single cells in the high-voltage battery pack is within the normal range, the balancing is determined to be completed and the battery balancing operation is terminated.

[0067] In one embodiment, the battery active balancing system also includes: when the voltage value of a single cell in the low-voltage battery pack is lower than a second preset voltage threshold, controlling the main control unit to send a high-voltage instruction to the slave control unit, so that the high-voltage battery pack replenishes power to the single cell in the low-voltage battery pack through the first DCDC module.

[0068] In an embodiment of the present invention, before the whole vehicle is powered by high voltage, the balancing switch is powered by the low-voltage battery pack through the second DCDC module. When the BMS system detects that the voltage of the single cell in the low-voltage battery pack is lower than the preset threshold, it sends a high-voltage command so that the high-voltage battery pack can supplement the single cell in the low-voltage battery pack through the first DCDC module. When the voltage of the single cell in the low-voltage battery pack reaches the preset threshold, the supplementary power ends. It should be noted that the high-voltage battery pack undertakes the main power supply task. In order to avoid the high-voltage battery pack itself being insufficient due to supplementary power to the low-voltage battery pack, it is necessary to ensure that the high-voltage battery pack has sufficient surplus power. Only when the high-voltage battery pack itself has sufficient power and can meet the normal operation requirements of the system, can the excess power be transferred to the low-voltage battery pack. If the high-voltage battery pack is insufficient or does not work properly, the supplementary power process may not be completed smoothly, and may even be interrupted in the middle of the supplementary power due to the exhaustion of the high-voltage battery pack. This will not only make the low-voltage battery pack unable to obtain sufficient power, but also may cause instability of the battery system. Therefore, it is required that the high-voltage battery pack must be in a normal working state and have sufficient surplus power to ensure that the supplementary power process can be completed continuously and stably.

[0069] As an optimization solution of the embodiment of the present invention, the embodiment of the present invention further provides an active balancing method, which is applicable to the above battery active balancing system, including:

[0070] Step 1: collect the cell working data of each single cell in the high-voltage battery pack in real time, and make a battery balancing judgment based on the cell working data. When it is determined that the high-voltage battery pack needs to be balanced, control the main control unit to send a battery balancing control instruction to the slave control unit, so that the slave control unit switches the working state of the balancing switch in the high-voltage battery pack; wherein the high-voltage battery pack includes a plurality of single cells;

[0071] Step 2: Control the second DCDC module to replenish power to the single cells in the high-voltage battery pack based on the turned-on balancing switch; wherein the second DCDC module is connected to the high-voltage battery pack through the first DCDC module, and the first DCDC module is used to convert the output voltage of the high-voltage battery pack to within the receiving voltage range of the second DCDC module.

[0072] In one embodiment, the active balancing method also includes: real-time detection of the voltage value of each single cell in the low-voltage battery pack; when there is a first single cell in the low-voltage battery pack whose voltage value is lower than a preset voltage threshold, if the high-voltage battery pack meets the preset power replenishment condition, controlling the high-voltage battery pack to replenish power to the first single cell; wherein the preset power replenishment condition is that the high-voltage battery pack is in a normal working state and has surplus power.

[0073] See also Figure 4 , Figure 4 A flowchart of an active equalization method provided in an embodiment of the present invention. "High voltage" generally refers to a state in which the voltage between battery cells is kept within a safe range in a battery management system (BMS), especially for a high-voltage battery pack. In this case, "high voltage" can be understood as the BMS system normally monitoring and managing the voltage of the battery cells during operation to ensure that they do not exceed the preset safety voltage upper limit. In an embodiment of the present invention, a high-voltage battery pack and a low-voltage battery pack are integrated in a lithium battery pack, i.e., a high-voltage battery pack and a low-voltage battery pack. When the high-voltage battery pack is already high-voltage, the slave control unit collects the high-voltage battery pack, i.e., the working data of the cells in the high-voltage battery pack, and sends it to the main control unit. The main control unit determines whether equalization is required based on the received working data of the cells. If necessary, the single cells that need to be equalized in the high-voltage battery pack are supplemented with electricity through the second DCDC module, and the high voltage output by the high-voltage distribution charge is transmitted to the low-voltage battery pack after level conversion by the first DCDC module, so as to power the single cells in the low-voltage battery pack. When the high-voltage battery pack is not at high voltage, if the low-voltage battery pack, that is, the voltage of the single cells in the low-voltage battery pack is lower than the preset threshold, the main control unit sends a high-voltage instruction so that the high-voltage battery pack can replenish the low-voltage battery pack through the first DCDC module.

[0074] In an embodiment of the present invention, an active balancing device is also provided, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, the above-mentioned active balancing method is implemented.

[0075] In an embodiment of the present invention, a computer-readable storage medium is further provided. The computer-readable storage medium includes a stored computer program. When the computer program is running, the device where the computer-readable storage medium is located is controlled to execute the above-mentioned active balancing method.

[0076] Exemplarily, the computer program may be divided into one or more modules, one or more modules are stored in a memory and executed by a processor to implement the present invention. One or more modules may be a series of computer program instruction segments capable of implementing specific functions, and the instruction segments are used to describe the execution process of the computer program in the active balancing device.

[0077] The active balancing device may be a computing device such as a desktop computer, a notebook, a PDA, and a cloud server. The active balancing device may include, but is not limited to, a processor, a memory, and a display. Those skilled in the art will appreciate that the above components are merely examples of active balancing devices and do not constitute a limitation on active balancing devices. The active balancing device may include more or fewer components than the components, or may combine certain components, or different components. For example, the active balancing device may also include input and output devices, network access devices, buses, and the like.

[0078] The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the active balancing device, and uses various interfaces and lines to connect various parts of the entire active balancing device.

[0079] The memory can be used to store computer programs and / or modules. The processor realizes various functions of the multi-device access platform processing device by running or executing the computer programs and / or modules stored in the memory and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, an application required for at least one function (such as a sound playback function, a text conversion function, etc.), etc.; the data storage area can store data created according to the use of the mobile phone (such as audio data, text message data, etc.), etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (FlashCard), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0080] Wherein, if the module based on active equalization is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Wherein, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium, etc. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0081] The embodiment of the present invention provides a battery active balancing system, which adopts an active balancing method. Through the cooperation of a first DCDC module and a second DCDC module, the system can effectively transfer the power of a high-voltage battery group to a low-voltage battery group, avoiding the waste of excess power consumed by resistors in a passive balancing method, and improving the energy utilization efficiency. Compared with the passive balancing method, the temperature rise of the battery group can be significantly reduced, which helps to keep the battery running at a suitable operating temperature and extend the battery life. The output voltage of the high-voltage battery group is switched to the receiving voltage range of the second DCDC module through the first DCDC module, ensuring that the energy of the high-voltage battery group can be effectively transmitted to the low-voltage battery group and the balancing circuit, thereby enhancing the adaptability and stability of the system. When the low-voltage battery group has sufficient or insufficient power, different balancing strategies are respectively adopted to ensure that efficient battery balancing can be achieved under various working conditions. Through the bidirectional energy flow of two DCDC modules and the balancing circuit, energy balancing between batteries can be achieved more effectively, avoiding the problem of small balancing current and limited effect in the passive balancing method.

[0082] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A battery active balancing system, characterized in that: include: A first DCDC module, a second DCDC module, a high voltage battery pack, a low voltage battery pack and a balancing circuit; The low-voltage battery pack is connected to the input end of the second DCDC module, the output end of the second DCDC module is connected to the input end of the balancing circuit, the output end of the balancing circuit is connected to the high-voltage battery pack, the high-voltage battery pack is connected to the input end of the first DCDC module, and the output end of the first DCDC module is connected to the low-voltage battery pack and the input end of the second DCDC module; When the low-voltage battery pack has sufficient power, the low-voltage battery pack balances the high-voltage battery pack through a first balancing circuit consisting of the low-voltage battery pack, the second DCDC module, the balancing circuit and the high-voltage battery pack; when the low-voltage battery pack has insufficient power, after the battery active balancing system is powered on, the first DCDC module switches the output voltage of the high-voltage battery pack to within the receiving voltage range of the second DCDC module, and the high-voltage battery pack balances the high-voltage battery pack through a second balancing circuit consisting of the high-voltage battery pack, the first DCDC module, the second DCDC module and the balancing circuit.

2. The battery active equalization system according to claim 1, characterized in that: The battery active balancing system includes a lithium battery pack, The lithium battery pack includes n single cells connected in series; m of the single cells connected in series are selected to construct the low-voltage battery pack, and the high-voltage battery pack is constructed based on the remaining (nm) single cells connected in series, where n and m are both positive integers greater than 1 and the value of (nm) is greater than m.

3. The battery active equalization system according to claim 1, characterized in that: The battery active balancing system also includes a power distribution module. The input end of the power distribution module is connected to the high-voltage battery pack, and the output end is connected to the input end of the first DCDC module; wherein the first DCDC module is used to convert the output voltage of the power distribution module into a receiving voltage range of the second DCDC module.

4. The battery active equalization system according to claim 1, characterized in that: The high-voltage battery pack includes a plurality of single cells, and the balancing circuit includes a plurality of balancing switches. The positive electrode of each of the single cells is connected to the first end of one of the balancing switches; The second end of the balancing switch is connected to the output end of the second DCDC module.

5. The battery active equalization system according to claim 1, characterized in that: The battery active balancing system further includes a master control unit and a slave control unit. The high-voltage battery pack includes a plurality of single cells. The slave control unit is used to collect the cell working data of each of the single cells in the high-voltage battery pack and send it to the master control unit; wherein the cell working data includes the single cell voltage value and the cell temperature; The master control unit performs battery balancing judgment based on the received battery cell working data, and sends a battery balancing control instruction to the slave control unit when the high-voltage battery pack needs to be battery balancing; The slave control unit is also used to switch the working state of the equalization circuit in the high-voltage battery pack according to the received battery equalization control instruction.

6. The active battery equalization system according to claim 5, characterized in that: The master control unit performs battery balancing judgment based on the received battery cell working data, and sends a battery balancing control instruction to the slave control unit when the high-voltage battery pack needs to be battery balancing, specifically including: Obtain a maximum single cell voltage value in the cell working data, compare the maximum single cell voltage value with the voltage values ​​of the remaining single cells, and when a difference between the maximum single cell voltage value and any single cell voltage value exceeds a first preset voltage threshold, control the master control unit to send a battery balancing control instruction to the slave control unit so that the slave control unit performs a battery balancing operation on the high-voltage battery pack.

7. The battery active equalization system as claimed in claim 5, characterized in that: The main control unit performs battery balancing judgment based on the received battery cell working data, and further includes: When the cell temperature in the cell working data exceeds a preset threshold, it is determined that the temperature of the high-voltage battery pack is abnormal, and the master control unit is controlled to send a battery balancing interruption instruction to the slave control unit, so that the slave control unit interrupts the battery balancing operation.

8. The battery active equalization system according to claim 5, characterized in that: The battery active balancing system further includes: When the voltage value of a single cell in the low-voltage battery pack is lower than a second preset voltage threshold, the main control unit is controlled to send a high-voltage instruction to the slave control unit, so that the high-voltage battery pack replenishes power to the single cell in the low-voltage battery pack through the first DCDC module.

9. An active equalization method, characterized in that: The active battery balancing system according to any one of claims 1 to 9 comprises: Step 1: collect the cell working data of each single cell in the high-voltage battery pack in real time, perform battery balancing judgment based on the cell working data, and when it is determined that the high-voltage battery pack needs to be battery balanced, control the main control unit to send a battery balancing control instruction to the slave control unit, so that the slave control unit switches the working state of the balancing switch in the high-voltage battery pack; wherein the high-voltage battery pack includes a plurality of single cells; Step 2, control the second DCDC module to replenish power to the single cells in the high-voltage battery pack based on the turned-on balancing switch; wherein the second DCDC module is connected to the high-voltage battery pack through the first DCDC module, and the first DCDC module is used to convert the output voltage of the high-voltage battery pack to within the receiving voltage range of the second DCDC module.

10. An active equalization method as claimed in claim 9, characterized in that: The active balancing method further comprises: Real-time detection of the voltage value of each single cell in the low-voltage battery pack; When there is a first single cell in the low-voltage battery pack whose voltage value is lower than a preset voltage threshold, if the high-voltage battery pack meets a preset power replenishment condition, the high-voltage battery pack is controlled to replenish power to the first single cell; wherein the preset power replenishment condition is that the high-voltage battery pack is in a normal working state and has surplus power.

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