Battery system, control method, medium, and vehicle

Abstract

Provided in the present application are a battery system, a control method, a medium, and a vehicle. The battery system comprises: a controller, a first capacitor, a first conversion branch, a second conversion branch, and a first battery and a second battery, which are connected in series, wherein both ends of the first capacitor are respectively connected to a positive electrode of the first battery and a negative electrode of the second battery; each conversion branch comprises a branch inductor and two switching tubes; the two switching tubes, after being connected in series, are connected in parallel with the first capacitor, and the branch inductor is connected between a series connection point of the first battery and the second battery and a series connection point of the two switching tubes; and the controller is used for controlling, on the basis of the current requested power received by the battery system, at least one of the first conversion branch and the second conversion branch to operate, such that the operating efficiency of the battery system is greater than the first efficiency. The present application can improve the operating efficiency of battery systems.

Description

A battery system, control method, medium, and vehicle

[0001] This application claims priority to Chinese Patent Application No. 202411206709.7, filed on August 30, 2024, entitled “A Battery System, Control Method, Medium and Vehicle”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of energy storage technology, specifically to battery systems, control methods, media, and vehicles. Background Technology

[0003] With the rapid development of electric vehicle technology, driving range and fast charging capabilities have become key competitive factors. However, traditional electric vehicle battery pack designs often use batteries with fixed capacity and performance, making it difficult to meet the diverse needs of the market. Some products combine multiple batteries into a single pack, utilizing the characteristics of different batteries to meet requirements for lifespan and energy efficiency; however, these battery packs have simple structures and controls, resulting in low operating efficiency. Summary of the Invention

[0004] The purpose of this application is to provide a battery system, control method, medium, and vehicle that can improve the operating efficiency of the battery system.

[0005] In a first aspect, this application discloses a battery system, which includes a controller, a first capacitor, a first conversion branch, a second conversion branch, and a first battery and a second battery connected in series; the two ends of the first capacitor are respectively connected to the positive terminal of the first battery and the negative terminal of the second battery; each conversion branch includes a branch inductor and two switching transistors; the two switching transistors are connected in series and then in parallel with the first capacitor, and the branch inductor is connected between the series connection point of the first battery and the second battery and the series connection point of the two switching transistors;

[0006] The controller is used to control at least one of the first conversion branch and the second conversion branch to operate based on the current requested power received by the battery system, so that the operating efficiency of the battery system is greater than the first efficiency.

[0007] Secondly, this application discloses a control method applied to a battery system, the battery system including a first capacitor, a first conversion branch, a second conversion branch, and a first battery and a second battery connected in series; the two ends of the first capacitor are respectively connected to the positive terminal of the first battery and the negative terminal of the second battery; each conversion branch includes a branch inductor and two switching transistors; the two switching transistors are connected in series and then in parallel with the first capacitor, and the branch inductor is connected between the series connection point of the first battery and the second battery and the series connection point of the two switching transistors; the method includes:

[0008] Based on the current requested power received by the battery system, at least one of the first conversion branch and the second conversion branch is controlled to operate, so that the working efficiency of the battery system is greater than the first efficiency.

[0009] Thirdly, this application provides a computer storage medium having a computer program stored thereon, which, when executed by a processor, implements the methods of the second aspect and any feasible implementation thereof.

[0010] Fourthly, this application provides a vehicle including the battery system of the first aspect and any feasible implementation thereof.

[0011] Combining the above technical solutions, this application operates based on at least one of the first and second conversion branches in the currently requested power control battery system. This allows the battery system's output power to meet demand and maintain high operating efficiency, thereby improving overall efficiency. Since the battery system includes a first and second battery connected in series, and the series connection point of the two batteries connects the first and second conversion branches, the battery system can be controlled to achieve various intelligent control modes under different scenarios, such as dual-battery series output, single-battery output, and dual-battery interactive power replenishment. This enables precise and efficient intelligent control of the battery system. Furthermore, due to the differences in lifespan and energy density between the two batteries, the advantages of long-life batteries and high-energy-density batteries can be combined and utilized. Long-life batteries can be used for cycling in the high SOC range, while high-energy-density batteries can be used in the low SOC range. This ensures the battery system's lifespan while increasing energy density, thereby significantly optimizing driving range and the battery system's weight and volume. Attached Figure Description

[0012] Figure 1 is a structural schematic diagram of a battery system provided in an embodiment of this application;

[0013] Figure 2 is a schematic diagram of the arrangement of batteries and cells in the battery system provided in the embodiments of this application;

[0014] Figure 3 is a schematic diagram showing the change in the working efficiency of the battery system with the output power;

[0015] Figure 4 is another structural schematic diagram of the battery system provided in an embodiment of this application;

[0016] Figure 5 is another structural schematic diagram of the battery system provided in the embodiment of this application;

[0017] Figure 6a is a schematic block diagram of the electric vehicle provided in this application, showing the battery system in a dual-battery interactive power replenishment mode when the vehicle is stationary.

[0018] Figure 6b is a schematic block diagram of the electric vehicle provided in this application, showing the battery system in a dual-battery interactive power replenishment mode during driving.

[0019] Figure 6c is a schematic block diagram of the battery system in single-cell output mode;

[0020] Figure 6d is a schematic block diagram of the battery system in dual-cell series output mode;

[0021] Figure 7 is a flowchart illustrating the control method provided in an embodiment of this application. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, system, product, or apparatus that comprises 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, products, or apparatuses.

[0024] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0025] Please refer to Figure 1, which is a schematic diagram of a battery system provided in an embodiment of this application. As shown in Figure 1, the battery system may include a controller 101, a first capacitor 104, a first conversion branch 106, a second conversion branch 110, and a first battery 102 and a second battery 103 connected in series. The two ends of the first capacitor 104 are connected to the positive terminal of the first battery 102 and the negative terminal of the second battery 103, respectively. Each conversion branch includes a branch inductor (107 and 113 in Figure 1) and two switching transistors (108 and 109, 111 and 112 in Figure 1). The two switching transistors in each conversion branch are connected in series and then in parallel with the first capacitor 104. The branch inductor in each conversion branch is connected between the series connection point of the first battery 102 and the second battery 103 and the series connection point of the two switching transistors in the conversion branch.

[0026] In this battery system, the controller 101 controls at least one of the first conversion branch 106 and the second conversion branch 110 to operate based on the current requested power received by the battery system, so that the operating efficiency of the battery system is greater than the first efficiency.

[0027] In this embodiment of the application, the controller 101 is a device with control capabilities. For example, the controller 101 may include a microcontroller unit (MCU).

[0028] Any battery, any conversion branch, and the first capacitor 104 can constitute a conversion circuit that can convert one DC voltage into another. For example, this conversion circuit can be a boost circuit to convert the voltage provided by the battery into a higher output voltage.

[0029] This battery system can be applied in electric vehicles. The first battery 102 and the second battery 103 in this system can provide energy to the electric vehicle, thereby providing power. The first battery 102 may include one or more first cells, which can be connected in series and / or parallel, enabling the first battery 102 to provide a certain voltage. Correspondingly, the second battery 103 may include one or more second cells, which can be connected in series and / or parallel, enabling the second battery 103 to provide a certain voltage. Figure 2 illustrates the arrangement of the batteries and cells in this battery system.

[0030] The positive electrode materials of the first and second battery cells can be various, such as lithium iron phosphate, ternary materials including nickel, cobalt, and manganese, lithium cobalt oxide, lithium manganese oxide, etc. The negative electrode materials of the first and second battery cells can be various, such as graphite, silicon, lithium metal, and materials without a negative electrode. Depending on the combination of positive and negative electrode materials, the chemical systems of the cells in the first battery 102 and the second battery 103 can include, but are not limited to, the following chemical systems: lithium iron phosphate-graphite system, lithium iron phosphate-silicon negative electrode system, lithium iron phosphate-silicon-carbon system, lithium iron phosphate-lithium metal negative electrode system, lithium iron phosphate-no-negative electrode system, ternary material-graphite system, ternary material-silicon negative electrode system, ternary material-silicon-carbon system, ternary material-lithium metal negative electrode system, ternary material-no-negative electrode system, etc. It is understood that the first and second battery cells can belong to different chemical systems; or they can belong to the same chemical system, but at least one electrode may have a different material ratio.

[0031] Understandably, the first battery 102 and the second battery 103 in this battery system satisfy the following condition: the rated capacity of the first battery 102 differs from the rated capacity of the second battery 103 by a first threshold. The first threshold can be set according to the actual scenario; for example, the first threshold can be 10%. This rated capacity represents the battery's energy storage capacity and can also represent the battery's discharge capacity. Although there is a certain difference between the rated capacity of the first battery 102 and the rated capacity of the second battery 103, the rated voltages of the two batteries can be basically the same, therefore the energy that the two batteries can store differs.

[0032] Optionally, the capacity of the first battery 102 may be greater than the capacity of the second battery 103, where the capacity may refer to the aforementioned rated capacity.

[0033] For example, the capacity of the first battery 102 may be greater than 1.1 times the capacity of the second battery 103. In this way, the two batteries in the battery system have different capacities, and the working efficiency of the battery system can be improved by combining the characteristics of the two batteries.

[0034] Alternatively, the first battery 102 and the second battery 103 in the battery system satisfy the following conditions: the energy density of the first battery 102 differs from the energy density of the second battery 103 by a second threshold, and the cycle life of the second battery 103 differs from that of the first battery 102 by a third threshold. The energy density of the battery can include at least one of mass energy density and volumetric energy density. The second and third thresholds can be set according to the actual scenario; for example, the second threshold can be 10%, and the third threshold can be 20%, which is not limited in this application. The cycle life of the battery can refer to the number of cycles in which the battery is repeatedly charged at 0.5C and discharged at 0.5C to its commonly used voltage range, and then decays to 80% of its rated capacity. That is, there are certain differences in the energy density and cycle life of the first battery 102 and the second battery 103. Specifically, among the first battery 102 and the second battery 103, the battery with a higher energy density has a shorter cycle life, and the battery with a lower energy density has a longer cycle life; therefore, these two batteries can be referred to as a long-life battery and a high-energy-density battery, respectively.

[0035] Optionally, the cycle life of the first battery 102 is greater than that of the second battery 103, and the mass energy density and / or volumetric energy density of the second battery 103 is greater than that of the first battery 102.

[0036] For example, the cycle life of the first battery 102 is greater than 1.2 times the cycle life of the second battery 103; or, the mass energy density and / or volumetric energy density of the second battery 103 is greater than 1.1 times the mass energy density and / or volumetric energy density of the first battery 102.

[0037] For example, a negative electrode-free battery with an energy density of 400Wh / kg and a cycle life of less than 200 cycles can be used as a high-energy-density battery, while a traditional lithium iron phosphate battery with an energy density of 200Wh / kg and a cycle life of more than 1500 cycles can be used as a long-life battery.

[0038] Understandably, the number of first cells in the first battery 102 and the number of second cells in the second battery 103 can be determined according to actual needs. For example, the first battery 102 and the second battery 103 can be designed to be combined in a 5:5 ratio of total capacity. This application does not impose any restrictions on this.

[0039] The aforementioned switching transistors can be transistors, insulated-gate bipolar transistors (IGBTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), etc., and this application does not impose any limitations on them. Taking MOSFETs as an example, the first and second terminals of each switching transistor can be the source and drain of the MOSFET, respectively. The control terminal of each switching transistor is used to receive control signals.

[0040] In this embodiment, when either the first conversion branch 106 or the second conversion branch 110 is working, one conversion branch in the battery system is operating, which can be referred to as single-phase operation, and the efficiency of the battery system at this time can be called single-phase efficiency. When both the first conversion branch 106 and the second conversion branch 110 are working, two conversion branches in the battery system are working, which can be referred to as two-phase operation, and the efficiency of the battery system at this time can be called two-phase efficiency. The aforementioned first efficiency is the smaller of the single-phase efficiency and the two-phase efficiency.

[0041] Figure 3 is a schematic diagram illustrating the change in battery system efficiency with output power. As shown in Figure 3, for the same output power, the efficiency differs between single-phase and two-phase operation. When the output power is less than a certain value, the battery system efficiency increases with increasing output power, and the efficiency of single-phase operation is higher than that of two-phase operation during this process. When the output power is greater than a certain value, the battery system efficiency decreases with increasing output power, and the efficiency of two-phase operation is higher than that of single-phase operation during this process. The output power shown in Figure 3 can be the currently requested power. The sweet spot in Figure 3 refers to the region where the output power is at a relatively high level of battery system efficiency.

[0042] The controller 101 in the battery system controls at least one of the first conversion branch 106 and the second conversion branch 110 to work based on the current requested power received by the battery system. In other words, it puts the battery system into a single-phase or two-phase working state, which can make the efficiency of the battery system greater than the first efficiency, thereby making the battery system always maintain a relatively high efficiency and improving the working efficiency of the battery system.

[0043] In one possible implementation, the controller 101 in the above-described battery system is specifically used for:

[0044] If the current requested power received by the battery system is less than a preset power threshold, control one of the first conversion branch 106 and the second conversion branch 110 to work.

[0045] If the current requested power received by the battery system is greater than the preset power threshold, both the first conversion branch 106 and the second conversion branch 110 are controlled to work.

[0046] Here, the preset power threshold can be the output power value corresponding to the intersection of the single-phase efficiency curve and the two-phase efficiency curve as shown in Figure 3. When the current requested power is less than the preset power threshold, controlling either the first conversion branch 106 or the second conversion branch 110 to operate is more efficient than controlling both conversion branches to operate, thus ensuring a high operating efficiency for the battery system and improving system efficiency. When the current requested power is less than the preset power threshold, controlling both conversion branches to operate is more efficient than controlling only one conversion branch to operate, thus still ensuring a high operating efficiency for the battery system. In this way, by selecting to control one or two conversion branches to operate based on the relationship between the current requested power and the preset power threshold, the battery system efficiency can always be kept greater than the first threshold, thereby improving the operating efficiency of the battery system.

[0047] In one possible implementation, the controller 101 is specifically used for:

[0048] If the current requested power received by the battery system is less than a preset power threshold, the duty cycle of the two switches in the first conversion branch 106 is controlled, and the two switches in the second conversion branch 110 are controlled to be in the off state; or,

[0049] If the current requested power received by the battery system is less than a preset power threshold, the duty cycle of the two switches in the second conversion branch 110 is controlled; and the two switches in the first conversion branch 106 are controlled to be in the off state; or,

[0050] When the current requested power received by the battery system is greater than the preset power threshold, the duty cycle of the two switches in the first conversion branch 106 and the duty cycle of the two switches in the second conversion branch 110 are controlled.

[0051] Specifically, controlling the duty cycle of two switches in any conversion branch, that is, controlling the two switches in the conversion branch to alternately (complementarily) turn on or off, that is, controlling the switching state of the two switches, can make the conversion branch work, thereby making the output power of the battery system the currently requested power.

[0052] Here, when it is necessary to control the operation of one conversion branch, the duty cycle of the two switches in that conversion branch is controlled. For example, when it is necessary to control the operation of the first conversion branch 106, the duty cycle of the two switches in the first conversion branch 106 can be controlled, and the switches in the second conversion branch 110 can be controlled to be in the off state. When it is necessary to control the operation of both conversion branches, the duty cycle of the two switches in the first conversion branch 106 and the second conversion branch 110 is controlled accordingly, so that both conversion branches can achieve power conversion.

[0053] In this embodiment, the operation of each conversion branch is controlled by controlling the duty cycle of the switching transistors in each conversion branch, thereby enabling the output power of the operating conversion branch and ensuring high operating efficiency of the battery system, thus improving system efficiency.

[0054] Please refer to Figure 4, which is another structural schematic diagram of the battery system provided in this application embodiment. Figure 4 is obtained based on Figure 1. As shown in Figure 4, the battery system also includes a first branch switch 114 and a second branch switch 115. The first branch switch 114 is connected between the branch inductor 107 in the first conversion branch 106 and the negative terminal of the first battery 102, and the second branch switch 115 is connected between the branch inductor 113 in the second conversion branch 110 and the negative terminal of the first battery 102.

[0055] The first branch switch 114 and the second branch switch 115 can be DC contactors or the like, used to connect or disconnect the circuit.

[0056] In this battery system, controller 101 is specifically used for:

[0057] If the current requested power received by the battery system is less than a preset power threshold, the system controls the first branch switch 114 to be in the ON state and the duty cycle of the two switches in the first conversion branch 106 to be adjusted, and controls the second branch switch 115 to be in the OFF state; or,

[0058] If the current requested power received by the battery system is less than a preset power threshold, the second branch switch 115 is controlled to be in the ON state, the duty cycle of the two switches in the second conversion branch 110 is adjusted, and the first branch switch 114 is controlled to be in the OFF state; or,

[0059] When the current requested power received by the battery system is greater than the preset power threshold, the first branch switch 114 and the second branch switch 115 are both turned on, and the duty cycle of the two switches in the first conversion branch 106 and the duty cycle of the two switches in the second conversion branch 110 are controlled.

[0060] In other words, the controller 101 can control the operation of each conversion branch by controlling the duty cycle of the two switches in each conversion branch. Furthermore, based on the relationship between the current requested power and the preset power threshold, when it is necessary to control the first conversion branch 106 to operate, the second branch switch 115 can be turned off, thereby preventing the second conversion branch 110 from operating; when it is necessary to control the second conversion branch 110 to operate, the first branch switch 114 can be turned off, thereby preventing the first conversion branch 106 from operating; when it is necessary to control both conversion branches to operate, both the first branch switch 114 and the second branch switch 115 can be turned on, ensuring that the connection between the two conversion branches and the first capacitor 104 is normal, thus enabling the battery system's output power to meet the requirements.

[0061] In this embodiment, two branch switches are provided in the battery system. Controlling the branch switch to turn off will disable the corresponding conversion branch, eliminating the need to control the switching transistor in that conversion branch. This method is simple to control and easy to operate. In case of a fault, turning off the branch switch can prevent damage to the components in the conversion branch, thus improving the safety of the battery system.

[0062] Please refer to Figure 5, which is another structural schematic diagram of the battery system provided in this application embodiment. Figure 5 is obtained based on Figure 4. As shown in Figure 5, the battery system also includes a main switch 105, the two ends of which are respectively connected to the positive terminal of the first battery 102 and one end of the first capacitor 104. Before controlling at least one of the conversion branches of the first conversion branch 106 and the second conversion branch 110 to work based on the current requested power received by the battery system, the controller 101 is also used to control the main switch 105 to be in the on state.

[0063] The main switch 105 can be a DC contactor or similar device, used to connect or disconnect the circuit.

[0064] In some embodiments, the battery system may include a main switch 105, but excludes the first branch switch 114 and the second branch switch 115. In some embodiments, the battery system may include a main switch 105 and a first branch switch 114, but excludes the second branch switch 115. This application does not impose any limitations on this.

[0065] In this embodiment, a main switch 105 is provided in the battery system to increase control flexibility. When a circuit fault occurs, the main switch 105 is turned off to avoid damage to components in the circuit and improve the reliability of the battery system.

[0066] The following describes how to control the operation of a transformation branch.

[0067] In the aforementioned battery system, when the currently requested power received by the battery system is less than a preset power threshold, controlling either the first conversion branch 106 or the second conversion branch 110 to operate may specifically include:

[0068] The first control signal is determined based on the current requested power, and the duty cycle of the two switches in the target conversion branch is controlled based on the first control signal. The target conversion branch is either the first conversion branch 106 or the second conversion branch 110.

[0069] For example, if it is necessary to control the operation of the first conversion branch 106, i.e., the target conversion branch is the first conversion branch 106, then the controller 101 can perform proportional-integral control on the difference between the currently requested power and the power of the first conversion branch 106 to obtain a first control signal. Based on the first control signal, the controller controls the duty cycle of the two switches in the first conversion branch 106, thereby controlling the two switches to be turned on or off. The first switch 108 and the second switch 109 are complementary in their conduction.

[0070] Optionally, the controller 101 can obtain the target current or target voltage based on the current requested power, and perform closed-loop control based on the target current or target voltage to obtain a first control signal. Based on the first control signal, the controller controls the duty cycle of the two switching transistors in the target conversion branch, thereby controlling the two switching transistors to be turned on or off.

[0071] In this way, by controlling the duty cycle of two switching transistors in any conversion branch of the battery system, one conversion branch of the battery system can be made to work, ensuring that the battery system has a high working efficiency and improving the system's working efficiency.

[0072] The following section explains how to control both transformation branches to work.

[0073] In one possible implementation, in the above-described battery system, when the currently requested power received by the battery system is greater than a preset power threshold, both the first conversion branch 106 and the second conversion branch 110 are controlled to operate. Specifically, this may include:

[0074] The second and third control signals are determined based on the current requested power and the target correspondence. The duty cycle of the two switches in the first conversion branch 106 is controlled based on the second control signal, and the duty cycle of the two switches in the second conversion branch 110 is controlled based on the third control signal. The target correspondence is used to indicate the power distribution relationship between the first conversion branch 106 and the second conversion branch 110 when they work together.

[0075] Understandably, the target correspondence is obtained in advance, and the current requested power can be obtained by controller 101. Based on the current requested power and target correspondence, a second control signal and a third control signal can be obtained. Then, based on the second control signal, the duty cycle of the two switches in the first conversion branch 106 is controlled, thereby controlling the two switches to be turned on or off. And based on the third control signal, the duty cycle of the two switches in the second conversion branch 110 is controlled, thereby controlling the two switches to be turned on or off.

[0076] In this way, by controlling the duty cycle of the two switching transistors in the two conversion branches of the battery system based on the correspondence between the current requested power and the target, both conversion branches of the battery system can be made to work and the output power can meet the requirements, thus ensuring that the battery system has a high working efficiency and improving the system efficiency.

[0077] Furthermore, the controller 101 is specifically used for:

[0078] The power allocation ratio corresponding to the maximum operating efficiency is determined based on the correspondence between the current requested power and the target power received by the battery system; the target correspondence is used to describe the correspondence between the requested power, the power allocation ratio and the operating efficiency.

[0079] The first and second powers are determined based on the power allocation ratio corresponding to the maximum working efficiency and the current requested power.

[0080] The second control signal is determined based on the first power, and the third control signal is determined based on the second power.

[0081] Furthermore, the controller 101 is specifically used for:

[0082] The second control signal is determined by performing proportional-integral control based on the difference between the first power and the power of the first conversion branch 106.

[0083] The third control signal is determined by performing proportional-integral control based on the difference between the second power and the power of the second conversion branch 110.

[0084] Specifically, the first power and the second power can be determined by looking up the table and interpolation based on the current requested power and the preset target correspondence (i.e., the power-efficiency table).

[0085] Optionally, the controller 101 may obtain a first target current or a first target voltage based on the first power, and perform closed-loop control based on the first target current or the first target voltage to obtain a second control signal, and control the duty cycle of the two switching transistors in the first conversion branch 106 based on the second control signal.

[0086] Optionally, the controller 101 may obtain a second target current or a second target voltage based on the second power, and perform closed-loop control based on the second target current or the second target voltage to obtain a third control signal, and control the duty cycle of the two switching transistors in the second conversion branch 110 based on the third control signal.

[0087] The following describes how to obtain the target correspondence.

[0088] When only one of the first conversion branch 106 and the second conversion branch 110 is working, the relationship between the requested power and the system efficiency is obtained. Based on this, the requested power-system efficiency curve (i.e., single-phase efficiency curve) of one conversion branch working can be plotted.

[0089] When both the first conversion branch 106 and the second conversion branch 110 are operating, for each requested power, the system efficiency corresponding to each power allocation ratio is measured under different requested power conditions. Specifically, the power allocation ratio can be between 1% and 99%, varying in 1% increments. For example, if the requested power X is allocated at a power allocation ratio of y%, then the power allocated to the first conversion branch 106 is X*y%, and the power allocated to the second conversion branch 110 is X*(100%-y%). Each switch is controlled based on these requested power and allocation ratios to obtain the system efficiency corresponding to the requested power and power allocation ratio. This allows for the determination of the correspondence between requested power, power allocation ratio, and system efficiency, enabling the plotting of the requested power-power allocation ratio-system efficiency curve (i.e., the two-phase efficiency curve) for both conversion branches. The correspondence obtained in this scenario is the target correspondence described above.

[0090] When the efficiency curves obtained for single-phase and two-phase operation are plotted on the same graph, a power-efficiency relationship diagram similar to Figure 3 above can be obtained. The two-phase efficiency curve in Figure 3 is the two-phase efficiency curve under a 50%-50% power distribution ratio.

[0091] Based on this target correspondence, when the requested power is the current requested power, the system efficiency corresponding to different power allocation ratios is queried to obtain the power allocation ratio corresponding to the maximum system efficiency. The current requested power is then allocated according to this corresponding power allocation ratio to obtain the aforementioned first power and second power. Based on the first power and second power, the second control signal and third control signal are obtained respectively, controlling the duty cycle of the switching transistors in the two conversion branches. In this way, it can be ensured that the highest global efficiency can always be obtained in the process of controlling the duty cycle of each switching transistor, thereby improving the working efficiency of the battery system.

[0092] In this embodiment, by controlling the operation of the appropriate conversion branch based on the current requested power, the output power can meet the requirements, and high operating efficiency can be achieved. Furthermore, compared to controlling a single conversion branch, controlling two conversion branches separately improves control flexibility. Simultaneously, through independent dual-path control, the system can achieve faster dynamic response, optimize efficiency, and reduce current fluctuations, thereby lowering the performance requirements for inductors and capacitors.

[0093] In one possible implementation, the two switching transistors in the first switching branch 106 are the first switching transistor 108 and the second switching transistor 109, and the two switching transistors in the second switching branch 110 are the third switching transistor 111 and the fourth switching transistor 112.

[0094] When both the first switching branch 106 and the second switching branch 110 are working, the phase difference between the first switch 108 and the third switch 111 is 180 degrees; and / or, the phase difference between the second switch 109 and the fourth switch 112 is 180 degrees.

[0095] Here, since all four switching transistors need to be controlled when both conversion branches are working, controlling each switching transistor in the above manner can ensure that the output power of the two conversion branches meets the requirements and improve the system's working efficiency.

[0096] The following section describes the operation of the battery system in specific application scenarios.

[0097] In one possible implementation, when the battery system is in internal charging mode, the controller 101 controls the duty cycle of the two switches in the first conversion branch 106 and the duty cycle of the two switches in the second conversion branch 110 to form a first boost circuit and a second boost circuit, so that the second battery 103 charges the first battery 102 through the first boost circuit and the second boost circuit. The internal charging mode indicates that there is a difference in the state of charge (SOC) between the first battery 102 and the second battery 103.

[0098] In one possible implementation, when the SOC of the first battery 102 is less than a first power threshold and the difference between the SOC of the second battery 103 and the SOC of the first battery 102 is greater than a preset threshold, the battery system is in an internal charging mode.

[0099] Understandably, the remaining state of a battery, also known as the state of charge (SOC), is the percentage of the battery's rated capacity remaining. It reflects the battery's remaining capacity and indicates its ability to continue operating. The SOC is 0 when the battery is completely discharged and 1 when it is fully charged; it is typically expressed as 0–100%.

[0100] The aforementioned SOC is a parameter representing the state of battery power, but it can actually be replaced with other parameters representing the state of battery power, and this application does not impose any restrictions.

[0101] The aforementioned first battery level threshold can be set according to the actual scenario. This first battery level threshold indicates that the battery level is low and may need to be replenished. For example, the first battery level threshold can be 30%.

[0102] Understandably, when the SOC of the first battery 102 is less than the first power threshold, the difference between the SOC of the second battery 103 and the SOC of the first battery 102 is greater than a preset threshold. Therefore, the SOC of the second battery 103 is greater than or equal to the first power threshold, and thus the second battery 103 can be used to charge the first battery 102. Alternatively, the SOC of the second battery 103 may also be less than the first power threshold, but the SOC of the second battery 103 is greater than the SOC of the first battery 102. In this case, the second battery 103 can still be used to charge the first battery 102. In these situations, the controller 101 can control the first conversion branch 106 and the second conversion branch 110 to operate, so that the second battery 103 charges the first battery 102.

[0103] In this embodiment, when the battery system is in internal charging mode, the controller 101 in the battery system controls the first conversion branch 106 and the second conversion branch 110 to operate, forming a first boost circuit and a second boost circuit. When the output voltage of the first boost circuit and the second boost circuit exceeds a certain threshold, the first battery 102 receives energy input and is charged. Thus, the second battery 103 charges the first battery 102 through the first boost circuit and the second boost circuit.

[0104] Optionally, when the battery system is in internal charging mode, the controller 101 can also control the first conversion branch 106 or the second conversion branch 110 to work, forming a third boost circuit or a fourth boost circuit, so that the second battery 103 charges the first battery 102.

[0105] Optionally, the first battery 102 can charge the second battery 103 when the power of the second battery 103 is low.

[0106] In this application, if the battery being charged is a long-life battery and the battery providing charging energy is a high-energy-density battery, by using the high-energy-density battery to charge the long-life battery, the energy density of the entire battery system can be increased without affecting the lifespan of the battery system, thereby reducing the mass or volume of the battery system and improving the range of the electric vehicle.

[0107] Understandably, when the second battery 103 charges the first battery 102, or when the first battery 102 charges the second battery 103, if a load is connected to the output of the battery system, the battery system can provide energy to the load while simultaneously charging each other. If no load is connected to the output of the battery system, the two batteries in the system can charge each other. In other words, regardless of whether the electric vehicle is stationary or in motion, the battery with higher charge can replenish the charge of the battery with lower charge, thereby increasing the energy density of the battery system.

[0108] The above describes a scenario where one battery in a battery system charges another.

[0109] The following describes the scenario where a single battery is used to power a load in a battery system.

[0110] In the above battery system, the output terminal of the battery system can be used to connect a load; the first capacitor 104 is connected to the output terminal of the battery system;

[0111] When the battery system is in the first discharge mode, the controller 101 controls the duty cycle of the two switches in the first conversion branch 106 and the duty cycle of the two switches in the second conversion branch 110, so that the second battery 103 or the first battery 102 supplies power to the load. The first discharge mode indicates that one of the first battery 102 and the second battery 103 is discharging.

[0112] In one possible implementation, when the SOC of the second battery 103 is greater than a first charge threshold and less than a second charge threshold, the battery system is in a first discharge mode, where the second charge threshold is greater than the first charge threshold.

[0113] The second battery threshold can be set according to the actual scenario. For example, the second battery threshold can be 80%.

[0114] Understandably, at this time, one battery powers the load while the other battery is not working.

[0115] In this embodiment, by controlling both conversion branches to operate, one battery can be deactivated, and the voltage of the other battery can be boosted to supply the load. If the independently operating battery is a long-life battery, it is possible to use the long-life battery to power the load when the battery's SOC is within a suitable range, without using the high-energy-density battery. This ensures that the battery system's lifespan is not affected. Using the high-energy-density battery as the power source at low SOC increases the overall energy density of the battery system.

[0116] Optionally, when the battery system is in the first discharge mode, the controller 101 can also control the first conversion branch 106 or the second conversion branch 110 to work, so that the second battery 103 or the first battery 102 supplies power to the load separately.

[0117] Understandably, when the battery system includes a first conversion branch 106 and a second conversion branch 110, only the first conversion branch 106 or only the second conversion branch 110 can be controlled to operate, allowing one battery in the battery system to charge another, or allowing one battery in the battery system to supply power to the load independently. In this way, the other conversion branch can serve as a backup conversion branch, operating when one conversion branch fails, thus improving the reliability of the battery system.

[0118] The following describes a scenario where two batteries in a battery system are used together to power a load.

[0119] In the above battery system, the output terminal of the battery system can be used to connect a load; the first capacitor 104 is connected to the output terminal of the battery system; when the battery system is in the second discharge mode, the controller 101 is also used to control the branch switch in the first conversion branch 106 and the branch switch in the second conversion branch 110 to be turned off, so that the first battery 102 and the second battery 103 supply power to the load, and the second discharge mode indicates that the first battery 102 and the second battery 103 jointly supply power to the load.

[0120] When the battery system is in the second discharge mode, the SOC of both the first battery 102 and the second battery 103 is greater than the second charge threshold.

[0121] Understandably, since both batteries have a relatively high SOC at this time, they can be connected in series to directly power the load.

[0122] In this embodiment, when the SOC of two batteries in the battery system is high, both batteries can be used together to discharge externally, providing energy to the load and meeting its requirements. Since one of the batteries has a higher energy density or rated capacity, this embodiment improves the energy density of the battery system compared to a battery system using only one type of battery.

[0123] In one possible implementation, the aforementioned load can be an electric vehicle.

[0124] When the electric vehicle is in a stationary state (i.e., the battery system is not supplying power to the load) and one battery in the battery system is charging another battery, the aforementioned currently requested power can be the charging power of the battery being charged.

[0125] When the electric vehicle is in motion (i.e., the battery system is supplying power to the load) and one battery in the battery system is charging another battery, the aforementioned current requested power can be obtained based on the charging power of the battery being charged and the power demand of the electric vehicle.

[0126] When a single battery in the battery system supplies power to the load, the aforementioned current requested power can be the power required by the electric vehicle.

[0127] In one possible implementation, the battery system further includes a pre-charge switch and a pre-charge resistor; the pre-charge switch and pre-charge resistor are connected in series and then in parallel with the main switch 105. The pre-charge switch and pre-charge resistor can pre-charge the battery system before it starts operating, preventing damage to circuit components and improving system reliability.

[0128] Understandably, for the SOC ranges of less than the first energy threshold, between the first and second energy thresholds, and greater than the second energy threshold, the battery system can operate in several modes as described above: dual-battery interactive charging, single-battery output, and dual-battery series output. Adjustments can also be made according to preset or dynamic strategies, and this application does not impose limitations. For example, when the battery SOC is high, it can operate in single-battery output mode; when the battery SOC is medium, it can operate in dual-battery series output mode based on high power requirements, and so on. Figures 6a and 6b show schematic block diagrams of the battery system in dual-battery interactive charging mode in a stationary state and in a driving state, respectively. Figure 6c shows a schematic block diagram of the battery system in single-battery output mode, and Figure 6d shows a schematic block diagram of the battery system in dual-battery series output mode. The electric vehicle's motor is used as the load in the figures.

[0129] Please refer to Figure 7, which is a flowchart illustrating a control method provided in an embodiment of this application. This method can be applied to a battery system as shown in any of Figures 1, 4, and 5. The battery system includes a first capacitor, a first conversion branch, a second conversion branch, and a first battery and a second battery connected in series. The two ends of the first capacitor are respectively connected to the positive terminal of the first battery and the negative terminal of the second battery. Each conversion branch includes a branch inductor and two switching transistors. The two switching transistors are connected in series and then in parallel with the first capacitor. The branch inductor is connected between the series connection point of the first battery and the second battery and the series connection point of the two switching transistors.

[0130] This method includes, but is not limited to, the following steps:

[0131] S701: Based on the current requested power received by the battery system, control at least one of the first conversion branch and the second conversion branch to operate, so that the working efficiency of the battery system is greater than the first efficiency.

[0132] In one possible implementation, the method includes:

[0133] If the current requested power is less than the preset power threshold, control the duty cycle of the two switches in the first conversion branch; or, control the duty cycle of the two switches in the second conversion branch.

[0134] When the current requested power is greater than the preset power threshold, the duty cycle of the two switches in the first conversion branch and the duty cycle of the two switches in the second conversion branch are controlled.

[0135] In one possible implementation, the method includes:

[0136] When the current requested power is greater than the preset power threshold, a second control signal and a third control signal are determined based on the correspondence between the current requested power and the target. The duty cycle of the two switches in the first conversion branch is controlled based on the second control signal, and the duty cycle of the two switches in the second conversion branch is controlled based on the third control signal. The target correspondence is used to indicate the power distribution relationship between the first conversion branch and the second conversion branch when they work together.

[0137] In one possible implementation, the method includes:

[0138] The power allocation ratio corresponding to the maximum working efficiency is determined based on the current requested power and the target correspondence; the target correspondence is used to describe the correspondence between requested power, power allocation ratio and working efficiency;

[0139] The first and second powers are determined based on the power allocation ratio corresponding to the maximum working efficiency and the current requested power.

[0140] The second control signal is determined based on the first power, and the third control signal is determined based on the second power.

[0141] This application also provides a computer storage medium having a computer program stored thereon, which, when executed by a processor, implements the method shown in Figure 7 above.

[0142] This application also provides a vehicle that may include a battery system as illustrated in any of Figures 1, 4 and 5 above.

[0143] In this embodiment, by controlling the operation of at least one of the first and second conversion branches in the battery system based on the currently requested power, the output power of the battery system can meet the demand and maintain high operating efficiency, thereby improving operating efficiency. Since the battery system includes a first battery and a second battery connected in series, and the series connection point of the two batteries connects the first and second conversion branches, the battery system can be controlled to achieve various intelligent control modes in different scenarios, such as dual-battery series output, single-battery output, and dual-battery interactive power replenishment, achieving precise and efficient intelligent control of the battery system. Furthermore, since the two batteries have different lifespans and energy densities, the advantages of long-life batteries and high-energy-density batteries can be combined and utilized. Long-life batteries can be used for cycling in the high SOC range, while high-energy-density batteries can be used in the low SOC range. This ensures the battery system's lifespan while increasing energy density, thereby significantly optimizing the driving range and the weight and volume of the battery system.

[0144] The above description is an exemplary embodiment of this application. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

Claims

1. A battery system, wherein, The system includes a controller (101), a first capacitor (104), a first conversion branch (106), a second conversion branch (110), and a first battery (102) and a second battery (103) connected in series. The two ends of the first capacitor (104) are connected to the positive terminal of the first battery (102) and the negative terminal of the second battery (103), respectively. Each conversion branch includes a branch inductor and two switching transistors. The two switching transistors are connected in series and then in parallel with the first capacitor (104). The branch inductor is connected between the series connection point of the first battery (102) and the second battery (103) and the series connection point of the two switching transistors. The controller (101) is used to control at least one of the first conversion branch (106) and the second conversion branch (110) to work based on the current requested power received by the battery system, so that the working efficiency of the battery system is greater than the first efficiency.

2. The battery system as claimed in claim 1, wherein, The controller (101) is specifically used for: If the current requested power received by the battery system is less than a preset power threshold, one of the first conversion branch (106) and the second conversion branch (110) is controlled to work. If the current requested power received by the battery system is greater than the preset power threshold, both the first conversion branch (106) and the second conversion branch (110) are controlled to work.

3. The battery system as described in claim 1 or 2, wherein, The controller (101) is specifically used for: If the current requested power received by the battery system is less than a preset power threshold, the duty cycle of the two switches in the first conversion branch (106) is controlled, and the two switches in the second conversion branch (110) are controlled to be in the off state; or, If the current requested power received by the battery system is less than a preset power threshold, the duty cycle of the two switches in the second conversion branch (110) is controlled; and the two switches in the first conversion branch (106) are controlled to be in the off state; or, If the current requested power received by the battery system is greater than the preset power threshold, the duty cycle of the two switches in the first conversion branch (106) and the duty cycle of the two switches in the second conversion branch (110) are controlled.

4. The battery system according to any one of claims 1-3, wherein, The battery system also includes a first branch switch (114) and a second branch switch (115). The first branch switch (114) is connected between the branch inductor (107) in the first conversion branch (106) and the negative terminal of the first battery (102). The second branch switch (115) is connected between the branch inductor (113) in the second conversion branch (110) and the negative terminal of the first battery (102). The controller (101) is specifically used for: When the current requested power received by the battery system is less than a preset power threshold, the first branch switch (114) is controlled to be in the on state and the duty cycle of the two switches in the first conversion branch (106) is controlled to be in the off state. or, If the current requested power received by the battery system is less than a preset power threshold, the second branch switch (115) is controlled to be in the ON state and the duty cycle of the two switches in the second conversion branch (110) is controlled to be in the OFF state; or, When the current requested power received by the battery system is greater than the preset power threshold, the first branch switch (114) and the second branch switch (115) are both controlled to be in the on state, and the duty cycle of the two switches in the first conversion branch (106) and the duty cycle of the two switches in the second conversion branch (110) are controlled.

5. The battery system according to any one of claims 2-4, wherein, When the current requested power received by the battery system is less than a preset power threshold, the controller (101) is specifically used to: A first control signal is determined based on the current requested power, and the duty cycle of two switching transistors in the target conversion branch is controlled based on the first control signal. The target conversion branch is either the first conversion branch (106) or the second conversion branch (110).

6. The battery system according to any one of claims 2-4, wherein, When the currently requested power received by the battery system is greater than the preset power threshold, the controller (101) is specifically configured to: The second control signal and the third control signal are determined based on the current requested power and the target correspondence. The duty cycle of the two switches in the first conversion branch (106) is controlled based on the second control signal, and the duty cycle of the two switches in the second conversion branch (110) is controlled based on the third control signal. The target correspondence is used to indicate the power distribution relationship between the first conversion branch (106) and the second conversion branch (110) when they work together.

7. The battery system of claim 6, wherein, The controller (101) is specifically used for: The power allocation ratio corresponding to the maximum operating efficiency is determined based on the current requested power received by the battery system and the target correspondence; the target correspondence is used to describe the correspondence between the requested power, the power allocation ratio, and the operating efficiency. The first power and the second power are determined based on the power allocation ratio corresponding to the maximum working efficiency and the current requested power. The second control signal is determined based on the first power, and the third control signal is determined based on the second power.

8. The battery system of claim 7, wherein, The controller (101) is specifically used for: The second control signal is determined by performing proportional-integral control based on the difference between the first power and the power of the first conversion branch (106); The third control signal is determined by performing proportional-integral control based on the difference between the second power and the power of the second conversion branch (110).

9. The battery system according to any one of claims 2-8, wherein, The battery system also includes a main switch (105), the two ends of which are respectively connected to the positive terminal of the first battery (102) and one end of the first capacitor (104); before the controller (101) controls at least one of the first conversion branch (106) and the second conversion branch (110) to work based on the current requested power received by the battery system, the controller (101) is also used to control the main switch (105) to be in the on state.

10. The battery system according to any one of claims 1-9, wherein, When the battery system is in internal charging mode, the controller (101) controls the duty cycle of the two switches in the first conversion branch (106) and the duty cycle of the two switches in the second conversion branch (110) to form a first boost circuit and a second boost circuit, so that the second battery (103) charges the first battery (102) through the first boost circuit and the second boost circuit. The internal charging mode indicates that there is a difference in the state of charge (SOC) between the first battery (102) and the second battery (103).

11. The battery system of claim 10, wherein, When the SOC of the first battery (102) is less than a first power threshold, and the difference between the SOC of the second battery (103) and the SOC of the first battery (102) is greater than a preset threshold, the battery system is in the internal charging mode.

12. The battery system according to any one of claims 1-11, wherein, The output terminal of the battery system is used to connect to a load; the first capacitor (104) is connected to the output terminal of the battery system; When the battery system is in the first discharge mode, the controller (101) controls the duty cycle of the two switches in the first conversion branch (106) and the duty cycle of the two switches in the second conversion branch (110) so that the second battery (103) or the first battery (102) supplies power to the load. The first discharge mode indicates that one of the first battery (102) and the second battery (103) is discharging.

13. The battery system of claim 12, wherein, When the SOC of the second battery (103) is greater than the first charge threshold and less than the second charge threshold, the battery system is in the first discharge mode, and the second charge threshold is greater than the first charge threshold.

14. The battery system of claim 4, wherein, The output terminal of the battery system is used to connect to a load; the first capacitor (104) is connected to the output terminal of the battery system; When the battery system is in the second discharge mode, the controller (101) is also used to control the branch switch (114) in the first conversion branch (106) and the branch switch (115) in the second conversion branch (110) to be turned off, so that the first battery (102) and the second battery (103) supply power to the load. The second discharge mode indicates that the first battery (102) and the second battery (103) jointly supply power to the load.

15. The battery system according to any one of claims 1-14, wherein, The first battery (102) and the second battery (103) satisfy the following condition: the rated capacity of the first battery (102) differs from the rated capacity of the second battery (103) by a first threshold value; Alternatively, the first battery (102) and the second battery (103) satisfy the following conditions: the energy density of the first battery (102) differs from the energy density of the second battery (103) by a second threshold, and the cycle life of the second battery (103) differs from that of the first battery (102) by a third threshold.

16. The battery system according to any one of claims 1-15, wherein, The cycle life of the first battery (102) is greater than that of the second battery (103), and the mass energy density and / or volumetric energy density of the second battery (103) is greater than that of the first battery (102).

17. The battery system of claim 16, wherein, The cycle life of the first battery (102) is greater than 1.2 times that of the second battery (103); The mass energy density and / or volumetric energy density of the second battery (103) is greater than 1.1 times the mass energy density and / or volumetric energy density of the first battery (102).

18. The battery system of claim 16 or 17, wherein, The capacity of the first battery (102) is greater than that of the second battery (103).

19. The battery system of claim 18, wherein, The capacity of the first battery (102) is greater than 1.1 times the capacity of the second battery (103).

20. The battery system according to any one of claims 1-19, wherein, The two switches in the first conversion branch (106) are the first switch (108) and the second switch (109), and the two switches in the second conversion branch (110) are the third switch (111) and the fourth switch (112). When both the first switching branch (106) and the second switching branch (110) are working, the first switch (108) and the third switch (111) are 180 degrees out of phase; and / or, the second switch (109) and the fourth switch (112) are 180 degrees out of phase.

21. A control method, wherein, The method is applied to a battery system, which includes a first capacitor, a first conversion branch, a second conversion branch, and a first battery and a second battery connected in series. The two ends of the first capacitor are connected to the positive terminal of the first battery and the negative terminal of the second battery, respectively. Each conversion branch includes a branch inductor and two switching transistors. The two switching transistors are connected in series and then in parallel with the first capacitor. The branch inductor is connected between the series connection point of the first battery and the second battery and the series connection point of the two switching transistors. The method includes: Based on the current requested power received by the battery system, control at least one of the first conversion branch and the second conversion branch to operate, so that the working efficiency of the battery system is greater than the first efficiency.

22. The method of claim 21, wherein, The method includes: If the current requested power is less than a preset power threshold, control the duty cycle of the two switches in the first conversion branch; or, control the duty cycle of the two switches in the second conversion branch. When the current requested power is greater than the preset power threshold, the duty cycle of the two switches in the first conversion branch and the duty cycle of the two switches in the second conversion branch are controlled.

23. The method of claim 21 or 22, wherein, The method includes: When the current requested power is greater than the preset power threshold, a second control signal and a third control signal are determined based on the current requested power and the target correspondence. The duty cycle of the two switches in the first conversion branch is controlled based on the second control signal, and the duty cycle of the two switches in the second conversion branch is controlled based on the third control signal. The target correspondence is used to indicate the power distribution relationship between the first conversion branch and the second conversion branch when they work together.

24. The method of claim 23, wherein, The method includes: The power allocation ratio corresponding to the maximum working efficiency is determined based on the current requested power and the target correspondence; the target correspondence is used to describe the correspondence between requested power, power allocation ratio and working efficiency; The first power and the second power are determined based on the power allocation ratio corresponding to the maximum working efficiency and the current requested power. The second control signal is determined based on the first power, and the third control signal is determined based on the second power.

25. A computer storage medium having a computer program stored thereon, wherein, When the program is executed by the processor, it implements the method of any one of claims 21-24.

26. A vehicle, characterized in that, Includes the battery system as described in any one of claims 1-20.

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