Charging and discharging circuit of battery, charging and discharging control method and battery system

Abstract

The invention discloses a charging and discharging circuit of a battery, a charging and discharging control method and a battery system, and relates to the field of batteries, the battery can be charged or discharged through a charging and discharging switch module, and can also be charged or discharged more controllably through a bidirectional direct current-direct current conversion module. Two bidirectional charging and discharging channels are integrated in a charging and discharging circuit of a battery, so that the adaptability of the whole electrical architecture is improved. Through a bidirectional charging and discharging channel corresponding to the bidirectional DC-DC conversion module, the battery can meet the requirements of current-limiting charging, load pre-charging, energy transfer and supplement with other batteries and the like, and the utilization rate of battery energy is improved, so that energy redundancy management and emergency switching of the battery are realized, and the reliability of the battery is improved on the premise of improving the robustness. Low power consumption and intelligent control are realized; the bidirectional DC-DC conversion module is directly integrated in a charging and discharging loop of the battery, so that the design of an electrical framework of the battery is simplified, and the functions and the cost are improved.

Description

Technical Field

[0001] This invention relates to the field of batteries, and in particular to a battery charging and discharging circuit, a charging and discharging control method, and a battery system. Background Technology

[0002] In traditional automotive electrical and electronic architectures, the 12V low-voltage auxiliary battery is a critical component for vehicle startup, and the entire vehicle system requires an electrical architecture based on this battery to perform related functions. However, with the rapid development of new energy vehicle technologies, intelligence, integration, and electrification have placed new demands on automotive electrical and electronic architectures. Traditional lead-acid batteries are being gradually replaced by lithium-ion batteries, and the electrical architecture corresponding to 12V low-voltage auxiliary batteries is being gradually replaced by one corresponding to 48V low-voltage auxiliary batteries—a major trend. However, the existing electrical architecture corresponding to 48V low-voltage auxiliary batteries is insufficient to meet the automotive industry's comprehensive demands for improvements in energy recovery, energy utilization, and other aspects. Summary of the Invention

[0003] The purpose of this invention is to provide a battery charging and discharging circuit, a charging and discharging control method, and a battery system, aiming to provide a battery electrical architecture that can achieve energy recovery and higher energy utilization.

[0004] To solve the above-mentioned technical problems, the present invention provides a battery charging and discharging circuit, including a charging and discharging switch module, a bidirectional DC-DC converter module, and a control module;

[0005] The first terminal of the charge / discharge switch module is connected to the first terminal of the bidirectional DC-DC converter module and the first electrode of the battery, respectively. The second terminal of the charge / discharge switch module is connected to the second terminal of the bidirectional DC-DC converter module, and the common connection point is connected to the first bus terminal of the battery. The second electrode of the battery is connected to the second bus terminal of the battery. The output terminal of the control module is connected to the control terminal of the charge / discharge switch module and the control terminal of the bidirectional DC-DC converter module, respectively.

[0006] The control module is used to determine the charging mode of the battery based on the battery's operating conditions and to determine the discharging mode of the battery based on the load corresponding to the battery.

[0007] The charging method includes charging the battery by controlling the charge / discharge switch module to connect to the charging source; or, charging the battery by controlling the bidirectional DC-DC converter module to output the energy of the charging source to the battery.

[0008] The discharge method includes discharging the battery by controlling the charge / discharge switch module to connect to the load; or discharging the battery by controlling the bidirectional DC-DC converter module to output the battery's energy to the load.

[0009] Optionally, the bidirectional DC-DC converter module includes a first switch, a second switch, a third switch, a fourth switch, and an inductor;

[0010] The control terminals of the first switch, the second switch, the third switch, and the fourth switch are all connected to the output terminal of the control module. The first terminal of the first switch is connected to the first electrode of the battery and the first terminal of the charge / discharge switch module. The first terminal of the second switch is connected to the second terminal of the first switch and the first terminal of the inductor. The second terminal of the second switch is grounded. The first terminal of the third switch is connected to the second terminal of the charge / discharge switch module. The first terminal of the fourth switch is connected to the second terminal of the third switch and the second terminal of the inductor. The second terminal of the fourth switch is grounded.

[0011] To address the aforementioned technical problems, the present invention also provides a battery charging and discharging control method, applied to the charging and discharging circuit of the aforementioned battery, the charging and discharging control method comprising:

[0012] Determine the battery's operating condition while the battery is charging;

[0013] If the battery operating condition supports high-current charging, the charge / discharge switch module in the charge / discharge circuit is connected to the charging source so that the charging source charges the battery through the charge / discharge switch module.

[0014] If the battery operating condition does not support high-current charging, the bidirectional DC-DC converter module in the charging and discharging circuit is controlled to work so that the charging source charges the battery through the bidirectional DC-DC converter module.

[0015] Determine the load corresponding to the battery while it is discharging;

[0016] If the load supports high current discharge, the charge / discharge switch module in the charge / discharge circuit is controlled to connect to the load so that the battery discharges to the load through the charge / discharge switch module;

[0017] If the load does not support high-current discharge, the bidirectional DC-DC converter module in the charging and discharging circuit is controlled to operate based on the load conditions of the load, so that the battery discharges to the load through the bidirectional DC-DC converter module.

[0018] Optionally, if the load corresponding to the battery is a rechargeable load, then it is determined that the rechargeable load does not support high-current discharge.

[0019] The load conditions include the ambient temperature of the rechargeable load and the charging curve of the rechargeable load;

[0020] Controlling the operation of the bidirectional DC-DC converter module in the charging and discharging circuit based on the load conditions of the load includes:

[0021] Determine whether the ambient temperature of the rechargeable load is greater than a first high temperature threshold or less than a first low temperature threshold;

[0022] If the ambient temperature of the rechargeable load is less than or equal to the first high temperature threshold and greater than or equal to the first low temperature threshold, then the output voltage and output current of the bidirectional DC-DC converter module are set according to the charging curve of the rechargeable load, and the operation of the bidirectional DC-DC converter module is controlled based on the set output voltage and output current.

[0023] If the ambient temperature of the rechargeable load is greater than the first high temperature threshold or less than the first low temperature threshold, the first preset current is set as the output current of the bidirectional DC-DC converter module, and the bidirectional DC-DC converter module is controlled to work based on the first preset current. After a first preset time period, the process jumps to the step of determining whether the ambient temperature of the rechargeable load is greater than the first high temperature threshold or less than the first low temperature threshold.

[0024] Wherein, the first preset current is less than the output current determined based on the charging curve of the rechargeable load.

[0025] Optionally, if the load corresponding to the battery is a non-rechargeable load, then determine whether the non-rechargeable load is already in operation.

[0026] If so, then it is determined that the non-rechargeable load supports high-current discharge;

[0027] If not, then the non-rechargeable load is determined to not support high-current discharge;

[0028] The load conditions include the number of non-rechargeable loads and the equivalent impedance of the non-rechargeable loads;

[0029] Controlling the operation of the bidirectional DC-DC converter module in the charging and discharging circuit based on the load conditions of the load includes:

[0030] Determine whether the number of loads is greater than a preset number;

[0031] If the number of loads is less than or equal to the preset number, the required supply voltage for the non-rechargeable load is determined based on the equivalent impedance of the non-rechargeable load, and the supply voltage is set as the output voltage of the bidirectional DC-DC converter module, and the second preset current is set as the maximum value of the output current of the bidirectional DC-DC converter module.

[0032] Determine whether the state of charge of the battery is greater than a first preset value;

[0033] If the state of charge of the battery is greater than the first preset value, the bidirectional DC-DC converter module is controlled to work based on the set output voltage and output current.

[0034] If the state of charge of the battery is less than or equal to the first preset value, then determine whether the state of charge of the battery is less than the second preset value.

[0035] If the state of charge of the battery is less than the second preset value, the start-up time of the non-rechargeable load is determined, and the discharge duty cycle is determined based on the start-up time. The bidirectional DC-DC converter module is controlled to work according to the discharge duty cycle and based on the set output voltage and output current.

[0036] The discharge duty cycle is negatively correlated with the start-up time.

[0037] Optionally, before determining the load corresponding to the battery, the method further includes:

[0038] If the battery receives a discharge request, determine whether the state of charge of the battery has reached a third preset value;

[0039] If the state of charge of the battery reaches a third preset value, determine whether the cell voltage of the battery reaches a fourth preset value.

[0040] If the cell voltage reaches the fourth preset value, it is determined that the battery meets the discharge conditions, and it is determined whether the ambient temperature of the battery is greater than the second high temperature threshold or less than the second low temperature threshold.

[0041] If the ambient temperature of the battery is less than or equal to the second high temperature threshold and greater than or equal to the second low temperature threshold, then proceed to the step of determining the load corresponding to the battery;

[0042] If the ambient temperature of the battery is greater than the second high temperature threshold or less than the second low temperature threshold, the third preset current is set as the output current of the bidirectional DC-DC converter module, and the bidirectional DC-DC converter module is controlled to work based on the third preset current. After a third preset time period, the process jumps to the step of determining whether the ambient temperature of the battery is greater than the second high temperature threshold or less than the second low temperature threshold.

[0043] Optionally, the battery operating conditions include the ambient temperature and battery voltage of the battery;

[0044] The specific process for determining whether the battery operating conditions support high-current charging includes:

[0045] Determine whether the ambient temperature of the battery is greater than a second high temperature threshold or less than a second low temperature threshold;

[0046] If the ambient temperature of the battery is greater than the second high temperature threshold or less than the second low temperature threshold, it is determined that the battery operating condition does not support high current charging.

[0047] If the ambient temperature of the battery is less than or equal to the second high temperature threshold and greater than or equal to the second low temperature threshold, then determine whether the voltage difference between the battery voltage and the charging voltage of the charging source is greater than a preset threshold.

[0048] If the pressure difference is greater than the preset threshold, it is determined that the battery condition does not support high-current charging.

[0049] If the pressure difference is less than or equal to the preset threshold, then the battery condition is determined to support high-current charging.

[0050] Optionally, the battery operating conditions include the battery's charging curve;

[0051] Controlling the operation of the bidirectional DC-DC converter module in the charging and discharging circuit includes:

[0052] The output voltage and output current of the bidirectional DC-DC converter module are set according to the charging curve of the battery, and the operation of the bidirectional DC-DC converter module is controlled based on the set output voltage and output current.

[0053] or,

[0054] The output voltage of the bidirectional DC-DC converter module is set according to a preset voltage gradient, and the operation of the bidirectional DC-DC converter module is controlled based on the set output voltage.

[0055] or,

[0056] The output current of the bidirectional DC-DC converter module is set according to the preset charging current, and the operation of the bidirectional DC-DC converter module is controlled based on the set output current.

[0057] To address the aforementioned technical problems, the present invention also provides a battery system comprising a plurality of batteries, wherein at least one of the batteries is provided with a charging and discharging circuit as described above.

[0058] Optionally, the battery system includes a first battery and a second battery, both of which are provided with the charging and discharging circuit. The output terminal of the bidirectional DC-DC converter module in the charging and discharging circuit corresponding to the first battery is connected to the output terminal of the bidirectional DC-DC converter module in the charging and discharging circuit corresponding to the second battery.

[0059] The control module in the charging and discharging circuit corresponding to the first battery or the second battery is used for:

[0060] Determine whether the first or second battery corresponding to the control module is the main battery;

[0061] If so, the discharge mode of the battery is determined according to the load corresponding to the battery;

[0062] If not, after receiving the fault signal corresponding to the main battery, the discharge mode of the battery is determined according to the load corresponding to the battery.

[0063] This invention provides a battery charging and discharging circuit, which includes a charging and discharging switch module, a bidirectional DC-DC converter module, and a control module. The battery can be charged or discharged through the charging and discharging switch module, or it can be charged or discharged more controllably through the bidirectional DC-DC converter module. By integrating two bidirectional charging and discharging channels into the battery's charging and discharging circuit, the adaptability of the entire electrical architecture is improved. Through the bidirectional charging and discharging channels corresponding to the bidirectional DC-DC converter module, the battery can meet the requirements of current-limited charging, pre-charging of the load, energy transfer and replenishment with other batteries, etc., improving the battery's energy utilization rate, thereby realizing energy redundancy management and emergency switching of the battery. It can achieve low power consumption and intelligent control while improving robustness. The bidirectional DC-DC converter module is directly integrated into the battery's charging and discharging circuit, simplifying the design of the battery's electrical architecture and achieving a dual improvement in functionality and cost reduction.

[0064] The present invention also provides a battery charging and discharging control method and battery system, which have the same beneficial effects as the charging and discharging circuit of the battery described above. Attached Figure Description

[0065] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0066] Figure 1 A schematic diagram of a battery charging and discharging circuit provided by the present invention;

[0067] Figure 2 A schematic diagram of the specific circuit structure of a battery charging and discharging circuit provided by the present invention;

[0068] Figure 3 A schematic flowchart of a battery charging and discharging control method provided by the present invention;

[0069] Figure 4 This is a schematic diagram of the electrical architecture of the first battery system provided by the present invention;

[0070] Figure 5 A schematic diagram of the specific internal structure of the electrical architecture of the first battery system provided by the present invention;

[0071] Figure 6 This is a schematic diagram of the electrical architecture of the second battery system provided by the present invention;

[0072] Figure 7 This is a schematic diagram of the electrical architecture of the third battery system provided by the present invention;

[0073] Figure 8 A schematic flowchart of another battery charging and discharging control method provided by the present invention;

[0074] Figure 9 This invention provides a schematic diagram of the battery switching process for a redundant battery system. Detailed Implementation

[0075] The core of this invention is to provide a battery charging and discharging circuit, a charging and discharging control method, and a battery system. Through the bidirectional charging and discharging channel corresponding to the bidirectional DC-DC converter module, the battery can meet the requirements of current-limited charging, pre-charging of the load, energy transfer and replenishment with other batteries, etc., thereby improving the energy utilization rate of the battery. This enables energy redundancy management and emergency switching of the battery, and achieves low power consumption and intelligent control while improving robustness. The bidirectional DC-DC converter module is directly integrated into the battery charging and discharging circuit, simplifying the design of the battery electrical architecture and achieving a dual improvement in functionality and cost reduction.

[0076] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0077] See Figure 1 As shown, Figure 1This is a schematic diagram of the charging and discharging circuit of a battery provided by the present invention; see also Figure 2 As shown, Figure 2 This invention provides a schematic diagram of the specific circuit structure of a battery charging and discharging circuit; where KL30 represents the positive bus terminal of the battery, and KL31 represents the negative bus terminal of the battery. To solve the above-mentioned technical problems, this invention provides a battery charging and discharging circuit, including a charging and discharging switch module 1, a bidirectional DC-DC converter module 2, and a control module 3;

[0078] The first terminal of the charge / discharge switch module 1 is connected to the first terminal of the bidirectional DC-DC converter module 2 and the first electrode of the battery, respectively. The second terminal of the charge / discharge switch module 1 is connected to the second terminal of the bidirectional DC-DC converter module 2, and the common connection point is connected to the first bus terminal of the battery. The second electrode of the battery is connected to the second bus terminal of the battery. The output terminal of the control module 3 is connected to the control terminal of the charge / discharge switch module 1 and the control terminal of the bidirectional DC-DC converter module 2, respectively.

[0079] The control module 3 is used to determine the charging mode of the battery based on the battery's operating conditions and to determine the discharging mode of the battery based on the corresponding load.

[0080] Charging methods include charging the battery by connecting the charging power source through the charging and discharging switch module 1; or, charging the battery by controlling the bidirectional DC-DC converter module 2 to output the energy of the charging power source to the battery.

[0081] The discharge methods include controlling the charge / discharge switch module 1 to connect the load to discharge the battery; or controlling the bidirectional DC-DC converter module 2 to output the battery's energy to the load to discharge the battery.

[0082] It is easy to understand that, in order to ensure safety and energy utilization during battery charging and discharging, this application provides a novel bidirectional electrical architecture for batteries. In the battery charging and discharging circuit, a charging / discharging switch module 1 and a bidirectional DC-DC converter module 2 are simultaneously provided. The control module 3 flexibly selects either the charging / discharging switch module 1 or the bidirectional DC-DC converter module 2 to achieve battery charging and discharging. Both the charging / discharging switch module 1 and the bidirectional DC-DC converter module 2 support bidirectional energy flow corresponding to battery charging and discharging. The control module 3 can achieve battery charging and discharging by controlling the conduction mode of the charging / discharging switch module 1, and it can also achieve battery charging and discharging by controlling the operation of the bidirectional DC-DC converter module 2. When using the bidirectional DC-DC converter module 2 for battery charging and discharging, the control module 3 can adjust electrical parameters such as current and voltage during the charging and discharging process according to actual conditions, achieving a more controllable and flexible charging and discharging process.

[0083] It should be noted that this application specifically limits the specific types and implementation methods of the charge / discharge switch module 1, the bidirectional DC-DC converter module 2, and the control module 3. The charge / discharge switch module 1 can be implemented using various types of switching devices, such as MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). Specifically, the charge / discharge switch module 1 can be implemented using a single switching device or a bidirectional switch composed of two switches connected in reverse series. The bidirectional DC-DC converter module 2 can be implemented using a bridge circuit built with MOSFETs, etc. The control module 3 can be implemented using various types of controllers or processors, or it can directly reuse the battery's BMS (Battery Management System), or it can be implemented using electronic devices or computer-readable storage media that integrate charge / discharge control methods. The first electrode and the second electrode of the battery are internal electrodes of the battery, and the first electrode and the second electrode are the positive and negative electrodes, respectively. In a preferred embodiment, the first electrode is the positive electrode of the battery, and the second electrode is the negative electrode of the battery. The first bus terminal and the second bus terminal of the battery are two external wiring terminals that need to be consistent with the polarity of the corresponding electrodes. For example, when the first electrode is the positive electrode of the battery, the first bus terminal is the positive wiring terminal of the battery; when the first electrode is the negative electrode of the battery, the second bus terminal is the negative wiring terminal of the battery.

[0084] It is understood that the charging and discharging circuit of the battery provided in this application integrates four power flow paths. Path 1 is the power path through which the battery can discharge to the external environment with a small current. That is, by controlling the operation of the bidirectional DC-DC converter module 2, the energy of the battery is output to the load to discharge the battery. This power path can avoid voltage and current surges caused by instantaneous startup by discharging with a small current. Taking the battery as an example of an internal battery in a car, before starting the car, this path can be used to briefly charge the parasitic capacitive load of the 48V or 12V low-voltage load bus inside the car to avoid voltage and current surges caused by the transient closure of the battery discharge circuit during startup, and to prevent false triggering of overcurrent or short-circuit protection. This power path can also utilize the bidirectional DC-DC converter module 2 to perform voltage conversion such as boost and / or buck, thereby supplying power to loads of different voltage specifications according to the corresponding safe supply voltage; for example, if a 48V battery uses the charging and discharging circuit provided in this application, and the 48V battery is connected to a 12V load (e.g., another 12V battery), the bidirectional DC-DC converter module 2 can be used to directly buck charge or replenish the 12V load.

[0085] Path 2 is a power path for adaptive charging of the battery by an external charging source. This involves controlling the bidirectional DC-DC converter 2 to output energy from the charging source to the battery for charging. This power path allows the external charging source to charge the battery according to its operating conditions. In a preferred embodiment, the operation of the bidirectional DC-DC converter 2 is controlled according to the cell charging curve corresponding to the battery's internal cell type. This ensures that the energy from the external charging source (specifically, the output voltage) can charge the battery under the dynamic setting of the charging current and voltage according to the charging curve, and the charging cutoff voltage or current can be set based on the charging curve. This allows the charging process to adapt to battery performance and different cell types such as ternary lithium, lithium iron phosphate, and sodium-ion, adjusting the charging parameters (charging current, charging voltage, etc.) accordingly to avoid the risk of thermal runaway. This power path can also be used to charge batteries with charging sources of different voltage specifications. When the voltage specification of the charging source does not match the rated charging voltage of the battery, the bidirectional DC-DC converter module 2 can step down and / or step up the supply voltage output by the charging source before charging. This can effectively charge the battery without turning on any other charging source.

[0086] Path 3 is the power path where the battery discharges directly to the load connected to the external bus terminal through the activated charge / discharge switch module 1. Path 4 is the power path where the external charging source charges the battery directly through the activated charge / discharge switch module 1.

[0087] It should be noted that this application does not impose any particular limitations on the specific type and implementation method of the battery. Batteries of various voltage specifications and application scenarios are permitted, such as 48V low-voltage automotive batteries. Specifically, these can be lead-acid, NCM (Lithium Nickel-Cobalt-Manganese Oxide), lithium iron phosphate, sodium-ion, and other types of batteries. Similarly, this application does not impose any particular limitations on the specific type and implementation method of the charging power source. These can be determined based on the actual application scenario of the battery. For example, when the battery is an internal automotive battery, the charging power source can be an on-board charger. This is particularly applicable in automotive scenarios where redundant 48V and 12V low-voltage batteries are integrated simultaneously. As a charging and discharging circuit for the 48V and / or 12V low-voltage batteries, the bidirectional DC-DC converter module 2 in the charging and discharging circuit enables energy transfer between the electrically isolated 12V low-voltage bus and the 48V low-voltage bus. The bidirectional DC-DC converter module 2 provides a redundant path for charging and discharging the battery. The 48V low-voltage battery and the 12V low-voltage battery can replenish each other's power through the bidirectional DC-DC converter module 2 in the charging and discharging circuit to avoid power depletion.

[0088] Furthermore, when the charging and discharging circuit provided in this application is applied in automotive batteries, its architecture design can meet the differentiated requirements of customers for battery electrical architecture. It can help the low-voltage battery in the car to perform energy recovery and energy management through the bidirectional DC-DC converter module 2. There are many options for energy flow, which adapts to the current trend of EE architecture (Electrical / Electronic) updates and iterations, and enables it to adapt to the gradually increasing types of low-voltage loads. The functional design of the charging and discharging circuit provided in this application is more complete. The control module 3 integrates software to control the charging and discharging switch module 1 and the bidirectional DC-DC converter module 2. The software and hardware integration meets the refined design requirements of L2 (partial automation), L3 (conditional automation) or higher-level assisted driving for functional safety, monitoring and diagnosis, etc., and adapts to the requirements of new architectures of pure electric and hybrid vehicle platforms. Furthermore, it can support redundant battery designs in automobiles to the greatest extent. For example, the 12V low-voltage battery can be transitioned to a 48V low-voltage battery by configuring the charging and discharging circuit provided in this application for the 12V low-voltage battery. The boost and current limiting functions of the bidirectional DC-DC converter module 2 can be used to adapt the 12V low-voltage battery to the 48V architecture built by the 48V low-voltage battery in the automobile, thus meeting the compatibility requirements for the transition from 12V to 48V.

[0089] This application provides a battery charging and discharging circuit. By further integrating a bidirectional DC-DC converter module 2 on top of the charging and discharging switch module 1, the battery can meet the energy transfer and replenishment requirements for pre-charging, current-limiting charging, and compatibility with other voltage-specification electrical systems. This improves the adaptability of the battery's electrical architecture, effectively optimizes the battery's electrical architecture design and energy management logic, and expands its driving capability. In redundant battery systems, it can meet the needs of energy redundancy management and emergency switching without completely relying on an external charging source. While improving robustness, it achieves low power consumption and intelligent control. Especially when applied to automotive batteries, it can flexibly adapt to the ever-increasing new requirements of the vehicle's electronic and electrical architecture, simplifying the complex design of the vehicle's electronic and electrical architecture in the low-voltage power distribution area. It meets the usage requirements of different platforms, including pure electric vehicles (BEVs) and mild hybrid electric vehicles (MHEVs), achieving a dual improvement in functionality and cost reduction.

[0090] As an optional embodiment, the bidirectional DC-DC converter module 2 includes a first switch Q1, a second switch Q2, a third switch Q3, a fourth switch Q4, and an inductor L0;

[0091] The control terminals of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 are all connected to the output terminal of the control module 3. The first terminal of the first switch Q1 is connected to the first electrode of the battery and the first terminal of the charge / discharge switch module 1, respectively. The first terminal of the second switch Q2 is connected to the second terminal of the first switch Q1 and the first terminal of the inductor L0, respectively. The second terminal of the second switch Q2 is grounded. The first terminal of the third switch Q3 is connected to the second terminal of the charge / discharge switch module 1, and the first terminal of the fourth switch Q4 is connected to the second terminal of the third switch Q3 and the second terminal of the inductor L0, respectively. The second terminal of the fourth switch Q4 is grounded.

[0092] It is understood that a bridge circuit structure consisting of the first switch Q1, the second switch Q2, the third switch Q3, the fourth switch Q4, and the inductor L0 can be used to implement the bidirectional DC-DC converter module 2. This bidirectional DC-DC converter module 2 can flexibly realize bidirectional energy flow according to requirements and can achieve both boost and buck operating modes, thereby achieving bidirectional voltage adaptation between the battery and external components. Simultaneously, the internal inductor L0 is used as an energy storage and energy transfer element to achieve controllable and efficient bidirectional energy flow. This application does not specifically limit the specific types and implementation methods of the first switch Q1, the second switch Q2, the third switch Q3, the fourth switch Q4, and the inductor L0. The first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 can be implemented using MOSFETs, etc. Figure 2 As shown, the bidirectional DC / DC (Direct Current / Direct Current) converter module can be implemented using four MOSFETs and one inductor L0. To ensure safety, the charge / discharge switch module 1 and the bidirectional DC / DC converter module 2 are connected in series between the positive terminal and the positive bus terminal of the battery.

[0093] Specifically, the bidirectional DC-DC converter module 2 can be realized through a bridge circuit structure consisting of the first switch Q1, the second switch Q2, the third switch Q3, the fourth switch Q4, and the inductor L0. The structure is simple and easy to implement.

[0094] See Figure 3 As shown, Figure 3 The present invention provides a schematic flowchart of a battery charging and discharging control method; to solve the above-mentioned technical problems, the present invention also provides a battery charging and discharging control method, applied to the aforementioned battery charging and discharging circuit, the charging and discharging control method comprising:

[0095] S11: Determine the battery's operating condition while the battery is charging;

[0096] S12: If the battery operating conditions support high-current charging, control the charging and discharging switch module in the charging and discharging circuit to connect to the charging source so that the charging source charges the battery through the charging and discharging switch module.

[0097] S13: If the battery operating conditions do not support high-current charging, control the bidirectional DC-DC converter module in the charging and discharging circuit to work so that the charging source charges the battery through the bidirectional DC-DC converter module.

[0098] S14: Determine the load corresponding to the battery when the battery is discharging;

[0099] S15: If the load supports high current discharge, control the charge / discharge switch module in the charge / discharge circuit to connect the load so that the battery discharges to the load through the charge / discharge switch module.

[0100] S16: If the load does not support high current discharge, the bidirectional DC-DC converter module in the load condition control charging and discharging circuit is activated based on the load condition of the load, so that the battery discharges to the load through the bidirectional DC-DC converter module.

[0101] It's easy to understand that the two charging and two discharging methods for the battery need to be flexibly selected based on the actual application. The bidirectional DC-DC converter module serves as a supplement and alternative to the charge / discharge switch module. During battery charging, the first terminal of the bidirectional DC-DC converter module acts as the output, and the second terminal as the input. At this time, the external charging source can either charge the battery with a large current through the charge / discharge switch module or charge it with a limited current through the bidirectional DC-DC converter module. The choice between these two charging methods depends on the battery's operating conditions, specifically whether it requires a smaller current charge. For example, when the battery is in a special environment such as low or high temperature, large current charging can damage the battery, thus requiring a smaller current charge. Similarly, when the battery is in a pumping operation scenario, a smaller current charge is also needed. In these cases, charging the battery requires avoiding the risk of impact damage to the battery cells caused by the direct closure of the charge / discharge switch module; therefore, the bidirectional DC-DC converter module needs to be controlled to achieve charging. Alternatively, the charging method may be chosen when the battery's current operating conditions indicate that it does not support direct charging from the power source's output voltage. This application does not impose any special limitations on application scenarios where the battery has a low-current charging requirement, i.e., does not support high-current charging. It is not limited to the low-current charging requirement caused by factors such as temperature influence or voltage mismatch in this embodiment. It can also be the requirement in various scenarios where high-current charging may damage the battery or there may be abnormal transient impacts during charging.

[0102] On the other hand, when the battery discharges, the second terminal of the bidirectional DC-DC converter module serves as the output terminal, and the first terminal serves as the input terminal. At this time, the battery can discharge to the load with a large current through the charge / discharge switch module, or it can discharge to the battery with a limited current through the bidirectional DC-DC converter module. These two discharge methods need to be determined based on the specific load conditions, judging whether the load corresponding to the current battery has a small current power supply requirement. There are various ways to implement the load connected to the battery, including but not limited to another battery, various voltage-specification loads, and other devices or modules with power supply requirements. This application does not impose any particular limitations here. Especially when the charge / discharge circuit is applied to a 48V low-voltage battery in an automobile, it can flexibly adapt to the vehicle's power distribution network, discharging the 48V bus, 12V bus, 48V load, 12V load, and 12V low-voltage battery in the vehicle, and supporting discharge with different discharge currents. During vehicle startup, the bidirectional DC-DC converter module can pre-charge the vehicle's capacitive loads, avoiding the high-current surge during startup. Furthermore, it can improve the convenience of charging the vehicle's internal batteries by discharging other batteries (such as 12V low-voltage batteries), supporting battery redundancy design in automobiles. This application does not specifically limit the method for determining whether a load supports high-current battery discharge; the specific determination can be made based on the load type, number of loads, and load operating conditions.

[0103] It should be noted that the battery charging and discharging control method provided in this application is also the internal control logic of the control module in the battery charging and discharging circuit. The control module controls the charging and discharging switch module and the bidirectional DC-DC converter module according to the battery charging and discharging control method provided in this application to achieve different charging and discharging processes. The control module can achieve functions such as pre-charging of the battery to the load, small current power supply, and current-limited charging by controlling the specific working mode of the bidirectional DC-DC converter module. Furthermore, it can flexibly adjust the charging current and discharging current by adjusting the working mode of the bidirectional DC-DC converter module, flexibly adapting to different electrical and vehicle architectures. Specifically, the control module can use driver chips or other methods to control the operation of each switch in the bidirectional DC-DC converter module, thereby realizing different working modes of the bidirectional DC-DC converter module.

[0104] For a description of the battery charging and discharging control method provided by the present invention, please refer to the above-described embodiment of the battery charging and discharging circuit; the present invention will not be described again here.

[0105] As an optional embodiment, if the load corresponding to the battery is a rechargeable load, it is determined that the rechargeable load does not support high-current discharge.

[0106] The load conditions include the ambient temperature of the rechargeable load and the charging curve of the rechargeable load;

[0107] The bidirectional DC-DC converter module in the load-based load condition control charging and discharging circuit operates, including:

[0108] Determine whether the ambient temperature of the rechargeable load is greater than a first high temperature threshold or less than a first low temperature threshold;

[0109] If the ambient temperature of the rechargeable load is less than or equal to the first high temperature threshold and greater than or equal to the first low temperature threshold, the output voltage and output current of the bidirectional DC-DC converter module are set according to the charging curve of the rechargeable load, and the operation of the bidirectional DC-DC converter module is controlled based on the set output voltage and output current.

[0110] If the ambient temperature of the rechargeable load is greater than the first high temperature threshold or less than the first low temperature threshold, the first preset current is set as the output current of the bidirectional DC-DC converter module, and the bidirectional DC-DC converter module is controlled to work based on the first preset current. After a first preset time period, the process jumps to the step of determining whether the ambient temperature of the rechargeable load is greater than the first high temperature threshold or less than the first low temperature threshold.

[0111] The first preset current is less than the output current determined based on the charging curve of the rechargeable load.

[0112] It is understandable that the battery's load can be another rechargeable device, which may require the battery to discharge and recharge itself due to low or insufficient power. When the load is rechargeable, the specific discharge method of the battery needs to be determined based on the ambient temperature and / or charging curve of the rechargeable load. If the ambient temperature of the rechargeable load is at an extremely high temperature (above a first high temperature threshold) or an extremely low temperature (below a first low temperature threshold), high-current charging will damage the rechargeable load. Therefore, the battery needs to discharge with a small current through a bidirectional DC-DC converter module to charge the rechargeable load with a small current. In this case, the output current of the bidirectional DC-DC converter module can be limited by a preset small current, i.e., a first preset current, to achieve the small-current discharge process. If the ambient temperature is suitable, within the appropriate temperature range corresponding to the first high temperature threshold and the first low temperature threshold, the output voltage and output current of the bidirectional DC-DC converter module can be further configured according to the charging curve of the rechargeable load itself, thereby achieving a safe charging process that conforms to the characteristics of the rechargeable load.

[0113] It should be noted that this application does not impose any special limitations on the specific values ​​of the first high temperature threshold and the first low temperature threshold, etc., and they can be determined based on the recommended operating temperature of the rechargeable load. The first high temperature threshold is greater than the first low temperature threshold. Similarly, this application does not impose any special limitations on the specific value of the first preset current, etc., as long as it is a small current less than the normal charging current of the rechargeable load. Furthermore, this application does not impose any special limitations on the specific determination method of the ambient temperature of the rechargeable load and the charging curve. Finally, this application does not impose any special limitations on the specific value of the first preset time period.

[0114] It should be noted that in practical applications, various preconditions can be identified based on the specific conditions of the rechargeable load to determine whether low-current charging is required and how to configure the output current and / or output voltage of the bidirectional DC-DC converter module, not limited to the preconditions described in this embodiment. The charging requirements of the rechargeable load are determined by identifying the preconditions, and then the bidirectional DC-DC converter module is activated to charge the load battery according to the charging requirements. The rechargeable load can specifically be various types of batteries, including lead-acid, NCM (Lithium Nickel-Cobalt-Manganese Oxide), lithium iron phosphate, and sodium-ion batteries.

[0115] Furthermore, the load conditions also include the terminal voltage of the rechargeable load and the charging voltage threshold of the rechargeable load; the discharge stop condition is confirmed by the terminal voltage and charging voltage threshold of the rechargeable load; when the rechargeable load meets the charging stop condition, the battery can disconnect the current-limiting discharge circuit of the bidirectional DC-DC converter module; if the charging stop condition is not met, it continues to discharge for the rechargeable load; alternatively, after a pre-set dead time of the second preset time period after stopping operation, it can switch to the discharge main circuit corresponding to the charge / discharge switch module and discharge externally according to path 3 to meet the power supply needs of other loads at any time. The specific value of the second preset time period is not specifically limited in this application and can be flexibly set according to actual needs; a preferred value range is 10-100ms.

[0116] Specifically, the load-based load condition control charging and discharging circuit includes a bidirectional DC-DC converter module to operate, so that after the battery discharges to the load through the bidirectional DC-DC converter module, it also includes:

[0117] Determine whether the terminal voltage of the rechargeable load reaches the charging voltage threshold of the rechargeable load.

[0118] If so, the bidirectional DC-DC converter module will stop working to disconnect the discharge circuit between the battery and the rechargeable load;

[0119] After the bidirectional DC-DC converter module stops working for a second preset period of time, the discharge switch in the charge / discharge switch module is turned on.

[0120] As one specific embodiment, see Figure 4 As shown, Figure 4 This is a schematic diagram of the electrical architecture of the first battery system provided by the present invention. The vehicle-mounted DC-DC converter and vehicle-mounted inverter are internal structures of the vehicle-mounted charger. Taking the redundant design of a car with both 12V and 48V electrical systems, and assuming the car's electrical system aims to achieve full 48V application, the charging and discharging circuit of the battery provided in this application can be set in the car's 48V low-voltage battery. In this case, the load of the 48V low-voltage battery may be another 12V low-voltage battery in the car. The control module in the charging and discharging circuit corresponding to the 48V low-voltage battery will identify the preconditions corresponding to the rechargeable load: ambient temperature (whether it is a temperature scenario that affects cell discharge and lifespan, such as high temperature above 65℃ or low temperature below -40℃), battery type of the load (determining the specific type of rechargeable load and the corresponding charging curve), OCV voltage (Open Circuit Voltage), SOC (State of Charge), upper limit of charging current, and charging cut-off condition of the load. Based on these preconditions, it determines how the bidirectional DC-DC converter module should operate to charge the 12V low-voltage battery. The OCV voltage can be determined through methods such as the MAP mapping table stored in the BMS of the 12V low-voltage battery, and the SOC of the battery can be obtained by communication between the BMS of the 48V low-voltage battery and the BMS of the 12V low-voltage battery.

[0121] Specifically, the process involves several steps: First, determining whether a low-current discharge is needed to charge the rechargeable load. Second, identifying the load's battery type to determine the corresponding charging curve. When low-current discharge is not required, the bidirectional DC-DC converter module is configured to operate according to the charging curve of the rechargeable load, outputting appropriate discharge current and voltage to charge the load. Third, determining whether low-current discharge is needed by checking the load's OCV voltage; low-current discharge is preferred when there is a significant difference between the load's OCV voltage and the battery's OCV voltage. Fourth, determining the required discharge amount and duration by checking the load's battery SOC. Finally, limiting the output current of the bidirectional DC-DC converter module by checking the load's charging current limit, for example, by confirming that the maximum safe current that the load's battery cells can withstand is I0. L1max , then I DCDCmax <I L1max , where I DCDCmaxTo achieve the maximum output current of the bidirectional DC-DC converter module, while also considering the miniaturization design of the charging and discharging circuit, I DCDCmax Ideally, the value should be set as small as possible; a preferred embodiment is I. DCDCmax ≤20A. The charging cutoff condition of the load is determined to determine under what conditions charging can be stopped. For example, if the charging cutoff condition of the load is that charging stops when the load battery voltage reaches a set voltage threshold, then the bidirectional DC-DC converter module is controlled to stop working to stop discharging when the load's OCV voltage reaches the corresponding voltage threshold.

[0122] Specifically, the redundant energy flow channels achieved through the cooperation of bidirectional DC-DC converter modules and charge / discharge switch modules enable the battery to adapt to rechargeable loads of different capacities, types, and operating conditions, achieving functions such as mutual charging between batteries, greatly improving the scalability and reliability of the vehicle's electrical system (EE). In automotive electrical systems where 48V and 12V electrical systems coexist, the charging / discharge circuit allows the 48V low-voltage battery to not only supply power to 48V loads but also to directly charge between 48V and 12V batteries, improving the battery's application adaptability and robustness. Especially in MHEV and BEV applications, this charging / discharge circuit allows for more flexible support for electrical redundancy design of the entire vehicle, optimizing only the battery's charging / discharging circuit without affecting other aspects of the vehicle's architecture, effectively meeting the battery's scalability requirements.

[0123] As an optional embodiment, if the load corresponding to the battery is a non-rechargeable load, it is determined whether the non-rechargeable load is already in operation.

[0124] If so, then the non-rechargeable load is determined to support high-current discharge;

[0125] If not, then the non-rechargeable load is determined to not support high-current discharge;

[0126] The load condition includes the number of non-rechargeable loads and the equivalent impedance of the non-rechargeable loads;

[0127] The bidirectional DC-DC converter module in the load-based load condition control charging and discharging circuit operates, including:

[0128] Determine if the number of loads exceeds the preset number;

[0129] If the number of loads is less than or equal to the preset number, the required supply voltage for the non-rechargeable loads is determined based on the equivalent impedance of the non-rechargeable loads, and the supply voltage is set to the output voltage of the bidirectional DC-DC converter module, and the second preset current is set to the maximum value of the output current of the bidirectional DC-DC converter module.

[0130] Determine whether the battery's state of charge is greater than a first preset value;

[0131] If the battery's state of charge is greater than the first preset value, the bidirectional DC-DC converter module will operate based on the set output voltage and output current.

[0132] If the state of charge of the battery is less than or equal to the first preset value, then determine whether the state of charge of the battery is less than the second preset value.

[0133] If the battery's state of charge is less than the second preset value, the start-up time of the non-rechargeable load is determined, and the discharge duty cycle is determined based on the start-up time. The bidirectional DC-DC converter module is then controlled to operate according to the discharge duty cycle, based on the set output voltage and output current.

[0134] Among them, the discharge duty cycle is negatively correlated with the start-up time.

[0135] It is easy to understand that the battery load can be a normal, non-rechargeable working load. This non-rechargeable load has a power demand based on its own operating requirements, necessitating battery discharge to provide power. When the load is non-rechargeable, the specific battery discharge method needs to be determined based on the load's operating state. For non-rechargeable loads, a small current discharge from the battery is mainly required during the first start-up or startup to avoid impacting the non-rechargeable load during startup. Therefore, it can be directly determined whether the non-rechargeable load supports high-current battery discharge by judging whether it is currently in an operating state. If the non-rechargeable load is currently in an operating state, the battery can be driven by the normal charge / discharge switch module. If the non-rechargeable load is not currently in an operating state, it is best to use a bidirectional DC-DC converter module for current-limited discharge, prioritizing current-limited drive to ensure safety. This application does not specifically limit the specific method for determining whether the non-rechargeable load is in an operating state; this can be obtained through the control module's communication system. This application also does not specifically limit the specific type and implementation method of the non-rechargeable load.

[0136] Furthermore, after determining that a bidirectional DC-DC converter module is used to discharge and drive the non-rechargeable load, the specific discharge voltage and / or discharge current can be further determined based on the number of non-rechargeable loads and their equivalent impedance. Since the bidirectional DC-DC converter module uses current-limited discharge, the maximum output current of the module needs to be configured according to a pre-determined current limit value, i.e., the second preset current. When the number of loads is relatively small, battery discharge can support driving these loads. In this case, the supply voltage corresponding to the current non-rechargeable load can be calculated based on the equivalent impedance of the non-rechargeable load and the second preset current, and this supply voltage is configured as the output voltage of the bidirectional DC-DC converter module, supplying power to the non-rechargeable loads in a constant voltage manner. If the number of loads is large, battery discharge cannot support the power supply needs of all non-rechargeable loads. In this case, a preset number of non-rechargeable loads can be selected as discharge targets, or a command signal can be output to instruct other power sources to meet the power supply needs. Specific measures can be determined according to actual needs, and this application does not impose any special limitations here. The specific values ​​of the preset number and the second preset current are not particularly limited here and can be set and adjusted according to actual needs.

[0137] Furthermore, considering that the battery's own charge level also affects the power supply process to non-rechargeable loads, the battery's state of charge (SOC) can be determined when discharging power to non-rechargeable loads. When the battery's SOC is relatively high (greater than the first preset value) and there is sufficient charge for discharge, the bidirectional DC-DC converter module can be continuously operated according to the output voltage and output current set according to the load conditions. When the battery's SOC is relatively low (less than the second preset value) and the charge is low, the bidirectional DC-DC converter module can be intermittently operated according to a specific discharge duty cycle based on the non-rechargeable load's start-up time, thus preventing the battery charge from becoming too low while supplying power to the non-rechargeable load. If the battery's state of charge (SOC) is within the intermediate range (greater than or equal to the second preset value and less than or equal to the first preset value), the need for the bidirectional DC-DC converter module to operate continuously can be determined based on the startup time of the non-rechargeable load. When the startup time is very short and the non-rechargeable load needs to start up quickly, the bidirectional DC-DC converter module is controlled to operate continuously based on the set output voltage and output current. When the startup time is not very short, a predetermined discharge duty cycle is preferred, and the intermittent operation mode of the bidirectional DC-DC converter module is controlled according to the discharge duty cycle and based on the set output voltage and output current to ensure battery power. This application does not impose specific limitations on the specific values ​​of the first, second, and third preset values.

[0138] As a specific embodiment, when the battery load is a normal operating load and the non-rechargeable load is pre-charged by the bidirectional DC-DC converter module at a fixed second preset current, the preconditions for discharging the non-rechargeable load are identified based on the current load condition: ambient temperature (environmental conditions that affect the load's operating time, such as high temperature above 65℃ and low temperature below -40℃), load type and quantity, pre-charge control method, and the battery's own SOC (State of Charge, remaining battery capacity).

[0139] Specifically, by identifying ambient temperature, it's determined whether the power demand of non-rechargeable loads will be affected by the environment, thus determining the accurate power demand (e.g., supply voltage). The load type is determined to be a non-rechargeable, normally functioning load such as a motor, capacitor, or ECU (Electronic Control Unit); simultaneously, the number N of loads currently requesting startup is determined, and the battery discharge output voltage is limited by I. DCDCmax Preset quantity and I DCDCmax There is a positive correlation when I DCDCmax When the current is ≤20A, and the preset quantity is 3, the battery can normally meet the power supply needs of all non-rechargeable loads only when N≤3. The pre-charge control method mainly involves the battery's corresponding control module obtaining the equivalent impedance of the non-rechargeable loads via communication, including equivalent capacitive reactance and equivalent inductive reactance, and then determining the corresponding supply voltage according to the following two formulas:

[0140] U L =L×di / dt;

[0141] I C =C×du / dt;

[0142] Among them, U L Where I is the supply voltage required by the inductive load, L is the reference inductive reactance of the inductive load, and di / dt is the rate of change of current flowing through the inductive load; C The required supply current for the capacitive load is given by C, where C is the reference capacitive reactance of the capacitive load, and du / dt is the rate of change of voltage across the capacitive load.

[0143] Furthermore, by evaluating the load startup time, the following options can be selected:

[0144] When the battery SOC is ≥ 70%, the battery is fully charged and can be pre-charged to the external load under a fixed continuous current condition. There is no duty cycle limitation at this time. Both capacitive and inductive loads are pre-charged using a small current (the second preset current). A preferred reference value for the second preset current is I. L2 ≤5A, this current is set by the corresponding control module;

[0145] When the battery SOC is ≤30%, the remaining battery power is low. Therefore, external loads can be pre-charged using pulsed current. For both capacitive and inductive loads, a small current (second preset current) is used for pre-charging. At this time, PWM (Pulse Width Modulation) control can be used to control the bidirectional DC-DC converter module to operate intermittently according to a predetermined discharge duty cycle. The setting range of the discharge duty cycle DP is related to the start-up time T1 of the non-rechargeable load. A preferred embodiment is that when T1≤100ms, then 50%≤DP≤90%; when 1s≤T1, then 20%≤DP≤50%; other start-up times can be executed with a 50% discharge duty cycle.

[0146] Specifically, the system first selects which power path to use to control battery discharge based on the load's operating status, and then further determines the specific discharge method when discharging through the bidirectional DC-DC converter module based on the load's condition. By comprehensively considering the power supply requirements of the non-rechargeable load and the battery's charge status, the system optimizes the battery's discharge method.

[0147] As an optional embodiment, before determining the load corresponding to the battery, the method further includes:

[0148] If the battery receives a discharge request, determine whether the battery's state of charge has reached the third preset value;

[0149] If the battery's state of charge reaches the third preset value, determine whether the battery cell voltage has reached the fourth preset value.

[0150] If the cell voltage reaches the fourth preset value, the battery is determined to meet the discharge conditions, and it is determined whether the ambient temperature of the battery is greater than the second high temperature threshold or less than the second low temperature threshold.

[0151] If the ambient temperature of the battery is less than or equal to the second high temperature threshold and greater than or equal to the second low temperature threshold, then proceed to the step of determining the load corresponding to the battery.

[0152] If the ambient temperature of the battery is greater than the second high temperature threshold or less than the second low temperature threshold, the third preset current is set as the output current of the bidirectional DC-DC converter module, and the bidirectional DC-DC converter module is controlled to work based on the third preset current. After the third preset time period, the process jumps to the step of determining whether the ambient temperature of the battery is greater than the second high temperature threshold or less than the second low temperature threshold.

[0153] It is understandable that when the battery is discharging, it is necessary to further determine whether the battery itself supports high-current discharge. When the battery receives a discharge request corresponding to any load, it first judges one or more combinations of the battery's state of charge, battery cell voltage, and ambient temperature. Only when the battery's state of charge is relatively high and the cell voltage is relatively large is the battery deemed to meet the discharge conditions. Then, it is further determined whether high-current discharge will damage the battery based on the ambient temperature. Under extreme temperature conditions, a third preset current, a small current, is used for discharge. The specific values ​​of the third preset value, fourth preset value, second high temperature threshold, and second low temperature threshold are not particularly limited in this application and can be flexibly set according to the actual application scenario. The second high temperature threshold is greater than the second low temperature threshold. The specific value of the third preset time period is not particularly limited in this application. The specific value of the third preset current is not particularly limited in this application, but the third preset current needs to be less than the battery's normal discharge current. A preferred embodiment is a small current less than or equal to 5A. When the battery's state of charge and cell voltage are relatively low, the battery's BMS should preferably send a charging request to request charging in order to obtain sufficient charge for discharge.

[0154] Specifically, by pre-judging whether the battery itself meets the discharge conditions, the battery is ensured to effectively discharge to support the load power supply before entering the discharge operation, thus guaranteeing the effectiveness and reliability of the power supply.

[0155] As an optional embodiment, battery operating conditions include the battery's ambient temperature and battery voltage;

[0156] The specific process for determining whether a battery's operating conditions support high-current charging includes:

[0157] Determine whether the ambient temperature of the battery is greater than the second high temperature threshold or less than the second low temperature threshold;

[0158] If the ambient temperature of the battery is greater than the second high temperature threshold or less than the second low temperature threshold, the battery operating condition is determined to not support high current charging.

[0159] If the ambient temperature of the battery is less than or equal to the second high temperature threshold and greater than or equal to the second low temperature threshold, then determine whether the voltage difference between the battery voltage and the charging voltage of the charging source is greater than the preset threshold.

[0160] If the voltage difference is greater than the preset threshold, it is determined that the battery condition does not support high-current charging.

[0161] If the voltage difference is less than or equal to the preset threshold, the battery is determined to support high-current charging.

[0162] It's easy to understand that when charging a battery, the specific charging method needs to be determined based on the battery's operating conditions. This involves assessing the battery's ambient temperature and the voltage difference between the battery and the charging source. When the battery's ambient temperature is extreme, high-current charging can damage the battery; when the voltage difference between the battery and the charging source is large, directly applying high-current charging can cause a shock to the battery. This application does not impose specific limitations on the specific values ​​of preset thresholds; they can be set according to the specific conditions of the battery and the charging source.

[0163] Specifically, the charging method needs to be determined based on the real-time operating conditions of the battery to ensure reliable charging of the battery while ensuring safety.

[0164] As an optional embodiment, battery operating conditions include the battery's charging profile;

[0165] The bidirectional DC-DC converter module in the charging and discharging circuit controls the operation of the circuit, including:

[0166] The output voltage and output current of the bidirectional DC-DC converter module are set according to the battery charging curve, and the operation of the bidirectional DC-DC converter module is controlled based on the set output voltage and output current.

[0167] or,

[0168] The output voltage of the bidirectional DC-DC converter module is set according to the preset voltage gradient, and the operation of the bidirectional DC-DC converter module is controlled based on the set output voltage.

[0169] or,

[0170] The output current of the bidirectional DC-DC converter module is set according to the preset charging current, and the operation of the bidirectional DC-DC converter module is controlled based on the set output current.

[0171] Understandably, to ensure safety and battery performance, when it is determined that current-limited charging of the battery via a bidirectional DC-DC converter module is necessary, three different methods can be selected to achieve safe charging based on specific needs. The first method is to set the output voltage, output current, charging cut-off voltage, and charging cut-off current of the bidirectional DC-DC converter module according to the battery's charging curve, based on the battery's cell type. This allows the charging source to perform current-limited charging according to the corresponding charging curve, ensuring battery performance. The second method is to use stepped voltage regulation charging, setting the output voltage of the bidirectional DC-DC converter module according to a preset voltage gradient. The output voltage of the bidirectional DC-DC converter module gradually increases to improve charging efficiency while ensuring safety. The third method is constant current charging, charging the battery with a preset small current to fully ensure battery safety. This application does not specifically limit the specific implementation methods of the preset voltage gradient and preset charging current. The preset charging current needs to be less than the battery's normal charging current; a preferred embodiment is a small current less than or equal to 5A.

[0172] As a specific embodiment, taking a redundant design in a car with both 12V and 48V electrical systems, and assuming the car's electrical system aims for full 48V application, when an external charging source charges the 48V low-voltage battery, the power path is either path 2 or path 4. At this point, the following preconditions are identified based on the current battery operating conditions: ambient temperature (identifying temperature scenarios affecting battery charging and lifespan, such as high temperatures above 65℃ and low temperatures below -40℃), the battery type of the 48V low-voltage battery, the supply voltage of the charging source, the current voltage of the 48V low-voltage battery, and the current SOC of the 48V low-voltage battery. Ambient temperature is used to determine whether high-current charging is supported. The corresponding charging curve is determined based on the battery type. The voltage difference between the charging voltage and the current battery voltage is determined by the supply voltage of the charging source and the current voltage of the 48V low-voltage battery; a charging cutoff condition can also be set based on the real-time battery voltage. The current SOC of the battery determines whether charging is needed, or the SOC can be used to set the charging cutoff condition. The charging cutoff condition can also be set by limiting the charging time. This application does not specifically limit the specific implementation method of the battery charging cutoff condition.

[0173] If high-current charging is supported, the battery is charged via power path 4. If the ambient temperature is extreme or the voltage difference between the battery and charging voltage is too large, the bidirectional DC-DC converter module is activated via power path 2 for current-limited charging. Specific current-limited charging methods include: if the charging source is a 12V bus, the 48V low-voltage battery is boosted via the bidirectional DC-DC converter module. If the charging source is a 48V bus, the 48V low-voltage battery is charged using a stepped voltage regulation method via the bidirectional DC-DC converter module, with a preferred preset voltage gradient of 0.1V / s or 0.2V / s. Regardless of the type of charging source, the battery can be charged according to a fixed preset charging current. Regardless of the type of charging source, the real-time charging voltage, real-time charging current, and cutoff charging voltage and current can be set according to the determined battery charging curve to complete current-limited charging.

[0174] Specifically, through the cooperation of the charge / discharge switch module and the bidirectional DC-DC converter module, the charging method can be flexibly adjusted according to the battery operating conditions, effectively adapting to different types of batteries, charging according to the charging curve under extreme temperature conditions, and adapting to the chemical materials of the battery cells to reduce charging risks.

[0175] To address the aforementioned technical problems, the present invention also provides a battery system comprising a plurality of batteries, wherein at least one of the batteries is provided with a charging and discharging circuit as described above.

[0176] It's easy to understand that when designing redundant battery systems—that is, systems containing several mutually redundant battery units—one, some, or all of the batteries can have the aforementioned battery charging and discharging circuits. This allows for more flexible energy management of the entire battery system. For example, in a car battery system that simultaneously incorporates 48V and 12V low-voltage batteries, mutual charging between the two batteries is possible. This not only achieves battery redundancy but also redundancy in the charging and discharging process, adapting to the charging needs of batteries of different voltage levels and loads in any scenario. It meets the system design requirement that the low-voltage power bus always has energy, greatly improving the redundancy safety of low-voltage loads in automobiles. By directly integrating a bidirectional DC-DC converter module within the battery's charging and discharging circuit, additional installation, design, and production costs are avoided, resulting in strong scalability and further enhancing the overall competitiveness of batteries, especially low-voltage batteries.

[0177] For an introduction to the battery system provided by this invention, please refer to the embodiments of the battery charging and discharging circuit and the battery charging and discharging control method described above. This invention will not be repeated here.

[0178] As an optional embodiment, the battery system includes a first battery and a second battery. Both the first battery and the second battery are provided with charging and discharging circuits. The output terminal of the bidirectional DC-DC converter module in the charging and discharging circuit corresponding to the first battery is connected to the output terminal of the bidirectional DC-DC converter module in the charging and discharging circuit corresponding to the second battery.

[0179] The control module in the charging and discharging circuit corresponding to the first or second battery is used for:

[0180] Determine whether the first or second battery corresponding to the control module is the main battery;

[0181] If so, the battery discharge method is determined based on the corresponding load of the battery;

[0182] If not, after receiving the fault signal corresponding to the main battery, the discharge mode of the battery is determined according to the load corresponding to the battery.

[0183] It is understood that if two (or more) batteries in a battery system use the charging and discharging circuit provided in this application, the bidirectional DC-DC converter modules in each charging and discharging circuit can be directly connected by adding separate output terminals to the bidirectional DC-DC converter modules in the charging and discharging circuit, allowing the two batteries to charge each other directly. Specifically, the output terminals of the bidirectional DC-DC converter modules can be implemented by directly leading out independent physical wiring harnesses from the second end of the bidirectional DC-DC converter module; this application does not impose any particular limitations on this.

[0184] Furthermore, if the battery system contains two (or more) batteries that all utilize the charging and discharging circuit provided in this application, a main battery design is required. One battery serves as the main battery, and the other (or more) batteries serve as backup batteries. The main battery discharges according to the aforementioned charging and discharging control method to meet load requirements. The backup battery then begins discharging according to the aforementioned charging and discharging control method in the event of a main battery failure or insufficient charge. This application does not specifically limit the specific implementation of the fault signal; it can be generated under various abnormal conditions such as main battery failure or insufficient charge.

[0185] As one specific embodiment, see Figure 5 As shown, Figure 5 A schematic diagram of the specific internal structure of the electrical architecture of the first battery system provided by the present invention; Figure 5The illustration shows an application scenario where both a 12V low-voltage battery and a 48V low-voltage battery are installed in a car. In this case, the 48V low-voltage battery uses the charging and discharging circuit provided in this application, and the output terminal of the corresponding bidirectional DC-DC converter module is connected to the 12V bus and the 12V low-voltage battery. Energy flow between the 12V and 48V electrical systems is achieved through the bidirectional DC-DC converter module. (See also...) Figure 6 As shown, Figure 6 This is a schematic diagram of the electrical architecture of the second battery system provided by the present invention; Figure 6 The illustration shows an application scenario where two redundant 48V low-voltage batteries are installed in a car, and the car only has a 48V bus. In this case, both redundant 48V low-voltage batteries can use the charging and discharging circuit provided in this application. See also... Figure 7 As shown, Figure 7 This is a schematic diagram of the electrical architecture of the third battery system provided by the present invention; Figure 7 The illustration depicts an application scenario where two redundant 48V low-voltage batteries are simultaneously installed in a vehicle. The vehicle also contains both a 48V bus and a 12V bus. In this case, both redundant 48V low-voltage batteries can utilize the charging and discharging circuit provided in this application. Output terminals can be led out from any one or two bidirectional DC-DC converter modules to connect to the 12V bus, enabling energy flow between the 12V and 48V electrical systems through the bidirectional DC-DC converter modules. Figure 5 As shown, Figure 5 The illustration shows an application scenario in a car where both a 12V low-voltage battery and a 48V low-voltage battery are installed. In this case, both the 12V and 48V low-voltage batteries can use the charging and discharging circuit provided in this application. The output terminal of the bidirectional DC-DC converter module corresponding to the 48V low-voltage battery is led out and connected to the 12V bus and the 12V low-voltage battery. The energy flow between the 12V electrical system and the 48V electrical system is realized through the bidirectional DC-DC converter module.

[0186] Further, see Figure 8 As shown, Figure 8 A schematic flowchart of another battery charging and discharging control method provided by the present invention; as shown. Figure 5 As shown, taking a 48V low-voltage battery as the main battery and a 12V low-voltage battery as the backup battery as an example, under normal circumstances, the main battery PACK1 is responsible for supplying power to the 12V low-voltage battery or the workload. Its workflow is as follows: Figure 8As shown, charging and discharging are performed using the aforementioned charging and discharging control method. When the battery needs charging, the system determines whether to start charging via path 2 or path 4 based on the battery's ambient temperature, corresponding voltage difference, and SOC prerequisites. Charging stops when the battery's SOC is ≥95%; otherwise, charging continues. If extreme temperature changes occur while charging via path 4, the system switches to path 2 for current-limited charging. After charging is complete, the battery enters standby mode. If a discharge request is received, the battery enters discharge mode. If the battery receives a discharge request but its own charge is insufficient, it sends a charging request to the vehicle, which then charges the battery via the onboard charger using path 2 or path 4. If, while charging via path 2, the voltage difference between the battery and the charging source decreases to below a preset threshold, or the temperature returns to normal, the system switches to path 4 to improve charging efficiency. When the battery charge is low, the battery enters a power-lock mode, accepting only charging and not discharging.

[0187] When the vehicle is key-on and powered on, the main battery PACK1 is preferentially selected as the starting battery to support vehicle startup. The starting battery discharges through the charge / discharge switch module to start the vehicle. After startup is complete, the battery enters standby mode. Upon receiving a discharge request in standby mode, the battery enters discharge mode. In discharge mode, the battery determines whether to use path 1 or path 3 to discharge the load based on preconditions such as load type, ambient temperature, and its own SOC (State of Charge). The battery can determine whether the current load is rechargeable or non-rechargeable through vehicle communication. If the current load is non-rechargeable, path 1 is used for initial startup with a small current discharge. After a certain period of small current discharge or after the non-rechargeable load has finished starting, the system switches to path 3 for further discharge until the load is fully discharged. The charge / discharge switch module can only drive loads with the same voltage rating as the battery, i.e., 48V loads. If the current load is rechargeable (12V low-voltage battery), path 1 is used for current-limited discharge. Once the rechargeable load is fully charged, the discharge ends. After discharge, the battery returns to standby mode.

[0188] As another specific embodiment, see Figure 9 As shown, Figure 9 This is a schematic diagram of the battery switching process for a redundant battery system provided by the present invention. Figure 5 As shown, taking a 48V low-voltage battery as the main battery and a 12V low-voltage battery as the backup battery as an example, under normal circumstances, the main battery PACK1 is responsible for supplying power to the 12V low-voltage battery or the workload. Its workflow is as follows: Figure 8 and Figure 9As shown, during discharge, the system determines whether to use the main battery for discharge based on the main battery's state. The control flow for the main battery and backup battery during normal charging and discharging is similar to... Figure 8 If the main battery is used as the starting battery, the backup battery does not need to be discharged through the main switch circuit to start the vehicle; the load type can be determined directly.

[0189] The charging and discharging circuit provided in this application, through the design of a bidirectional DC-DC converter module, supports redundant charging and discharging processes in redundant battery systems, improves the redundancy scalability of the entire battery system, enhances the adaptability of the battery system to buses with different voltage specifications, and provides reliable expansion and feasibility support for EE architectures that simultaneously contain 12V and 48V electrical systems. Any one or more batteries in the battery system can adopt the standardized charging and discharging circuit provided in this application, thereby achieving redundant configuration using the same charging and discharging circuit. Through flexible combinations of charging and discharging strategies, multiple batteries can achieve parallel redundancy, and multiple batteries can achieve replenishment and energy recovery through mutual charging and discharging. This is suitable for various battery system hierarchical architectures, such as 12V+48V dual-battery redundant architectures, 48V+48V dual-battery redundant architectures, etc. In particular, by setting the charging and discharging circuit provided in this application in two or more batteries in the battery system, a flexible and highly adaptable battery system can be achieved, realizing a battery electrical architecture with higher energy utilization.

[0190] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatuses disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section. It should also be noted that in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0191] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A charge-discharge circuit of a battery, characterized by comprising: The charging and discharging circuit comprises a charging and discharging switch module, a bidirectional DC-DC conversion module and a control module. The first end of the charging and discharging switch module is connected with the first end of the bidirectional DC-DC conversion module and the first electrode of the battery respectively, the second end of the charging and discharging switch module is connected with the second end of the bidirectional DC-DC conversion module, and the common connection point is connected with the first bus terminal of the battery, the second electrode of the battery is connected with the second bus terminal of the battery, and the output end of the control module is connected with the control end of the charging and discharging switch module and the control end of the bidirectional DC-DC conversion module respectively. The control module is used for determining the charging mode of the battery according to the battery working condition of the battery and determining the discharging mode of the battery according to the corresponding load of the battery. The charging mode comprises connecting the charging source to the battery by controlling the charging and discharging switch module or outputting the energy of the charging source to the battery by controlling the bidirectional DC-DC conversion module to charge the battery. The discharging mode comprises connecting the load to the battery by controlling the charging and discharging switch module or outputting the energy of the battery to the load by controlling the bidirectional DC-DC conversion module to discharge the battery.

2. The charge-discharge circuit of a battery according to claim 1, wherein The bidirectional DC-DC conversion module comprises a first switch, a second switch, a third switch, a fourth switch and an inductor. The control end of the first switch, the control end of the second switch, the control end of the third switch and the control end of the fourth switch are connected with the output end of the control module, the first end of the first switch is connected with the first electrode of the battery and the first end of the charging and discharging switch module respectively, the first end of the second switch is connected with the second end of the first switch and the first end of the inductor respectively, the second end of the second switch is grounded, the first end of the third switch is connected with the second end of the charging and discharging switch module, the first end of the fourth switch is connected with the second end of the third switch and the second end of the inductor respectively, and the second end of the fourth switch is grounded.

3. A charge-discharge control method of a battery, characterized by, The charging and discharging control method applied to the battery charging and discharging circuit of claim 1 or 2 comprises: In the case of battery charging, determining the battery working condition of the battery; If the battery working condition supports large-current charging, controlling the charging and discharging switch module in the charging and discharging circuit to connect the charging source, so that the charging source charges the battery through the charging and discharging switch module; If the battery working condition does not support large-current charging, controlling the bidirectional DC-DC conversion module in the charging and discharging circuit to work, so that the charging source charges the battery through the bidirectional DC-DC conversion module; In the case of battery discharging, determining the corresponding load of the battery; If the load supports large-current discharging, controlling the charging and discharging switch module in the charging and discharging circuit to connect the load, so that the battery discharges to the load through the charging and discharging switch module. If the load does not support large current discharge, a bidirectional DC-DC conversion module in the charge-discharge circuit is controlled to work based on a load working condition of the load, so that the battery is discharged to the load through the bidirectional DC-DC conversion module.

4. The charge and discharge control method of a battery according to claim 3, characterized by, If the load corresponding to the battery is a chargeable load, it is determined that the chargeable load does not support large current discharge. The load working condition includes an ambient temperature of the chargeable load and a charging curve of the chargeable load. Controlling the bidirectional DC-DC conversion module in the charge-discharge circuit to work based on the load working condition of the load includes: It is determined whether the ambient temperature of the chargeable load is greater than a first high-temperature threshold or less than a first low-temperature threshold. If the ambient temperature of the chargeable load is less than or equal to the first high-temperature threshold and greater than or equal to the first low-temperature threshold, an output voltage and an output current of the bidirectional DC-DC conversion module are set according to the charging curve of the chargeable load, and the bidirectional DC-DC conversion module is controlled to work based on the set output voltage and output current. If the ambient temperature of the chargeable load is greater than the first high-temperature threshold or less than the first low-temperature threshold, a first preset current is set as the output current of the bidirectional DC-DC conversion module, and the bidirectional DC-DC conversion module is controlled to work based on the first preset current, and after a first preset time period, the step of determining whether the ambient temperature of the chargeable load is greater than the first high-temperature threshold or less than the first low-temperature threshold is jumped to. The first preset current is less than the output current determined based on the charging curve of the chargeable load.

5. The charge and discharge control method of a battery according to claim 3, wherein If the load corresponding to the battery is an unchargeable load, it is determined whether the unchargeable load is already in a running state. If yes, it is determined that the unchargeable load supports large current discharge. If no, it is determined that the unchargeable load does not support large current discharge. The load working condition includes a load quantity of the unchargeable load and an equivalent impedance of the unchargeable load. Controlling the bidirectional DC-DC conversion module in the charge-discharge circuit to work based on the load working condition of the load includes: It is determined whether the load quantity is greater than a preset quantity. If the load quantity is less than or equal to the preset quantity, a power supply voltage required by the unchargeable load is determined based on the equivalent impedance of the unchargeable load, the power supply voltage is set as an output voltage of the bidirectional DC-DC conversion module, and a second preset current is set as a maximum value of an output current of the bidirectional DC-DC conversion module. It is determined whether the state of charge of the battery is greater than a first preset value. If the state of charge of the battery is greater than the first preset value, the bidirectional DC-DC conversion module is controlled to work based on the set output voltage and output current. If the state of charge of the battery is less than or equal to the first preset value, it is determined whether the state of charge of the battery is less than a second preset value. If the state of charge of the battery is less than the second preset value, a start-up time of the non-rechargeable load is determined, and a discharge duty cycle is determined based on the start-up time, and the bidirectional DC-DC conversion module is controlled to work based on the set output voltage and output current according to the discharge duty cycle. The discharge duty cycle is negatively correlated with the start-up time.

6. The charge and discharge control method of a battery according to claim 3, wherein Before determining the load corresponding to the battery, the method further comprises: If the battery receives a discharge request, it is determined whether the state of charge of the battery reaches a third preset value; If the state of charge of the battery reaches the third preset value, it is determined whether the cell voltage of the battery reaches a fourth preset value; If the cell voltage reaches the fourth preset value, it is determined that the battery meets the discharge condition, and it is determined whether the ambient temperature of the battery is greater than a second high-temperature threshold or less than a second low-temperature threshold; If the ambient temperature of the battery is less than or equal to the second high-temperature threshold and greater than or equal to the second low-temperature threshold, the step of determining the load corresponding to the battery is performed; If the ambient temperature of the battery is greater than the second high-temperature threshold or less than the second low-temperature threshold, a third preset current is set as the output current of the bidirectional DC-DC conversion module, the bidirectional DC-DC conversion module is controlled to work based on the third preset current, and after a third preset time period, the step of determining whether the ambient temperature of the battery is greater than a second high-temperature threshold or less than a second low-temperature threshold is performed.

7. The charge-discharge control method of a battery according to any one of claims 3 to 6, characterized by, The battery working condition includes the ambient temperature and the battery voltage of the battery. The specific process of determining whether the battery working condition supports large-current charging comprises: It is determined whether the ambient temperature of the battery is greater than a second high-temperature threshold or less than a second low-temperature threshold; If the ambient temperature of the battery is greater than the second high-temperature threshold or less than the second low-temperature threshold, it is determined that the battery working condition does not support large-current charging; If the ambient temperature of the battery is less than or equal to the second high-temperature threshold and greater than or equal to the second low-temperature threshold, it is determined whether the pressure difference between the battery voltage and the charging voltage of the charging source is greater than a preset threshold; If the pressure difference is greater than the preset threshold, it is determined that the battery working condition does not support large-current charging; If the pressure difference is less than or equal to the preset threshold, it is determined that the battery working condition supports large-current charging.

8. The charge and discharge control method of a battery according to claim 7, characterized by, The battery working condition includes the charging curve of the battery. Controlling the bidirectional DC-DC conversion module in the charging and discharging circuit to work comprises: The output voltage and output current of the bidirectional DC-DC conversion module are set according to the charging curve of the battery, and the bidirectional DC-DC conversion module is controlled to work based on the set output voltage and output current; Or, The output voltage of the bidirectional DC-DC conversion module is set according to a preset voltage gradient, and the bidirectional DC-DC conversion module is controlled to work based on the set output voltage; Or, The output current of the bidirectional DC-DC conversion module is set according to a preset charging current, and the bidirectional DC-DC conversion module is controlled to work based on the set output current.

9. A battery system characterized by, The battery system comprises a plurality of batteries, at least one of the plurality of batteries is provided with the charge-discharge circuit of the battery as claimed in claim 1 or 2.

10. The battery system of claim 9, wherein, The battery system comprises a first battery and a second battery, and the first battery and the second battery are both provided with the charge-discharge circuit, and an output terminal of a bidirectional DC-DC conversion module in the charge-discharge circuit corresponding to the first battery is connected with an output terminal of a bidirectional DC-DC conversion module in the charge-discharge circuit corresponding to the second battery; The control module in the charge-discharge circuit corresponding to the first battery or the second battery is used for: judging whether the first battery or the second battery corresponding to the control module is a main battery; if yes, determining a discharge mode of the battery according to a load corresponding to the battery; if no, after receiving a fault signal corresponding to the main battery, determining the discharge mode of the battery according to the load corresponding to the battery.

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