Battery system charging method and charging system for an electric vertical take-off and landing aircraft

Abstract

The application discloses a battery system charging method and charging system of an electric vertical take-off and landing aircraft. The charging method comprises the following steps: establishing electrical connection between each battery pack in the battery system and an external charging port to form a pre-charging connection loop corresponding to each battery pack; performing output loop detection; starting voltage discharge action on the high-voltage power grid on the aircraft to discharge the voltage of the high-voltage power grid on the aircraft to a preset threshold; analyzing the effective opening number of the pre-charging connection loop of the battery pack in the battery system, and opening pre-charging of the pre-charging connection loop with the effective opening number; and after pre-charging is completed, the battery system performs a charging process. Through the voltage discharge action on the high-voltage power grid on the aircraft, the application avoids power consumption caused by power-on of high-voltage loads, and through analysis of the minimum opening number of simultaneous pre-charging of multiple battery packs as the effective opening number, the working life of the battery system is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of electric vertical takeoff and landing (EVTOL) aircraft technology, and more particularly to a charging method and charging system for the battery system of an EVTOL aircraft. Background Technology

[0002] eVTOL (Electric Vertical Takeoff and Landing) is a new type of electric aircraft capable of vertical takeoff and landing. It combines the advantages of helicopters and fixed-wing aircraft, and has the advantages of low noise, low carbon emissions, flexibility and high efficiency. It is suitable for low-altitude scenarios such as urban commuting, logistics, sightseeing, and rescue.

[0003] In eVTOL systems, to reduce complexity and improve safety, the following designs are typically employed: 1. The battery system usually uses multiple battery packs connected in parallel; 2. High-voltage loads such as electric drives and DC-DC converters are directly connected to the high-voltage grid and lack controlled disconnection capabilities. However, this design introduces new problems. To stabilize voltage, protect power devices, and suppress noise in these high-voltage load designs, large X and Y capacitors are introduced, which are directly fed into the high-voltage grid. When the battery packs begin pre-charging, the power consumption of the high-voltage loads and the energy absorption by the introduced X and Y capacitors cause the pre-charging current to be lower than expected. This results in the pre-charging voltage failing to meet the preset time, preventing the main relay from closing and hindering normal battery charging, thus affecting the system's safety and reliability. Ensuring the pre-charging current and voltage meet the requirements would necessitate activating more battery packs, or even all battery packs, but this reduces battery pack lifespan and increases operating costs. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a charging method and charging system for the battery system of an electric vertical take-off and landing aircraft. By discharging the voltage of the high-voltage power grid on the aircraft, the power consumption caused by triggering the power supply of the high-voltage load is avoided. Furthermore, by analyzing the minimum number of battery packs that can be pre-charged simultaneously as the effective number of activations, the working life of the battery system is effectively improved.

[0005] This invention provides a charging method for the battery system of an electric vertical takeoff and landing (EVTOL) aircraft. The battery system of the EVTOL aircraft includes several battery packs connected in parallel to the aircraft's onboard high-voltage power grid. The charging method includes: Establish an electrical connection between each battery pack in the battery system and the external charging port to form a pre-charge connection circuit for each battery pack; Perform output circuit detection on the pre-charge connection circuit; Initiate voltage discharge to the high-voltage power grid on the aircraft, causing the voltage of the high-voltage power grid on the aircraft to discharge to a preset threshold. Based on the preset charging strategy, the effective number of pre-charge connection circuits of the battery pack in the battery system is analyzed, and the pre-charge of the effective number of pre-charge connection circuits is started. After pre-charging is completed, the main relay of the high-voltage power grid on the aircraft is closed, and the battery system executes the charging process.

[0006] Furthermore, the step of performing output circuit detection on the pre-charge connection circuit includes: An output circuit detection command is triggered by an external charging port, and all battery packs in the battery system respond to the output circuit detection command and feed back initial state information. Short circuit detection, insulation detection, and contactor adhesion detection are performed on the pre-charge connection circuit, and the detection status is fed back in real time. After the short circuit detection, insulation detection, and contactor adhesion detection are passed, the next step of voltage discharge operation is initiated.

[0007] Furthermore, the step of initiating the voltage discharge action on the high-voltage power grid of the aircraft, causing the voltage of the high-voltage power grid on the aircraft to discharge to a preset threshold, includes: Initiate a voltage discharge action on the high-voltage power grid on the aircraft to discharge the voltage of the high-voltage power grid on the aircraft to a first preset threshold. Extract the start-up voltage data of the high-voltage load connected to the high-voltage power grid on the aircraft. Initiate a secondary voltage discharge action on the high-voltage power grid on the aircraft, causing the voltage of the high-voltage power grid on the aircraft to be discharged from a first preset threshold to a second preset threshold, where the second preset threshold is less than the starting voltage data of the high-voltage load.

[0008] Furthermore, the initiation of the secondary voltage discharge action to the high-voltage power grid on the aircraft includes: Activate the active discharge function of the high-voltage load; Adjust the circuit parameters and discharge threshold of the discharge circuit of the high-voltage power grid on the aircraft. An external discharge circuit is connected to the high-voltage power grid on the aircraft. Furthermore, the analysis of the effective number of pre-charge connection circuits of the battery pack in the battery system based on the preset charging strategy includes: The effective number of precharge connection circuits of the battery pack in the battery system is determined by calculation, and / or by activation test.

[0009] Furthermore, the step of determining the effective number of pre-charge connection circuits of the battery pack in the battery system through calculation includes: Obtain the pre-charge resistance value of a single battery pack and the equivalent capacitance values ​​of X capacitor and Y capacitor in the high-voltage load of the high-voltage power grid on the aircraft. A standard first-order linear differential equation is established based on the capacitor charging characteristic formula. The pre-charging resistance value of the single battery pack and the equivalent capacitance values ​​of X capacitor and Y capacitor in the high-voltage load of the high-voltage grid on the aircraft are substituted into the standard first-order linear differential equation to obtain the pre-charging time constant and voltage division ratio corresponding to different activation numbers. Based on the preset precharge duration threshold and voltage compliance ratio, the precharge time constant and voltage division ratio corresponding to the different activation quantities are matched to select the minimum number of precharge connection circuits that meet the precharge requirements as the effective activation quantity.

[0010] Furthermore, determining the effective number of pre-charge connection circuits of the battery pack in the battery system through the activation test includes: In the initial state, the pre-charge connection circuits of all battery packs are opened to verify the feasibility of pre-charging at this time and the closing effectiveness of the main relay of the high-voltage power grid on the aircraft. Gradually reduce the number of pre-charge connection circuits opened in the battery pack, and verify the feasibility of pre-charging and the closing effectiveness of the main relay simultaneously after each adjustment; Record the minimum number of precharge connection circuits that must be opened to satisfy both precharge feasibility and the closing validity of the main relay, as the effective number of openings.

[0011] Furthermore, the precharging of the effective number of precharge connection circuits includes: When precharging the precharge connection circuit corresponding to the effective number of activations, precharging of all precharge connection circuits corresponding to the effective number of activations must be activated simultaneously.

[0012] Furthermore, after forming the pre-charge connection circuit, the method further includes: The pre-charge connection circuit is subjected to pre-charge connection detection, which includes hardware matching, specification requirement matching, connection parameter configuration matching, authentication and direct connection confirmation between the battery system and the external charging port.

[0013] The present invention also provides a battery system charging system for an electric vertical takeoff and landing (EVTOL) aircraft. The charging system is used to implement the aforementioned battery system charging method for an EVTOL aircraft. The charging system includes: A pre-charge connection circuit connection module is used to establish an electrical connection between each battery pack in the battery system and an external charging port, forming a pre-charge connection circuit corresponding to each battery pack. An output circuit detection module is used to perform output circuit detection on the precharge connection circuit. A voltage discharge action module is used to initiate a voltage discharge action on the high-voltage power grid on the aircraft, so that the voltage of the high-voltage power grid on the aircraft is discharged to a preset threshold. A precharge activation module is used to analyze the effective number of precharge connection circuits of the battery pack in the battery system based on a preset charging strategy, and activate the precharge of the effective number of precharge connection circuits. The charging module is used to close the main relay of the high-voltage power grid on the aircraft after pre-charging is completed, and the battery system performs a constant voltage charging process.

[0014] This invention provides a charging method and system for the battery system of an electric vertical takeoff and landing (EVTOL) aircraft. By discharging the primary and secondary voltages of the aircraft's high-voltage power grid, the voltage of the high-voltage power grid is lower than the starting voltage of the high-voltage load. This avoids power consumption caused by triggering the high-voltage load, ensuring that the pre-charging current and pre-charging voltage of the battery pack's pre-charging connection circuit reach the required levels within a preset time. This ensures the pre-charging operation of the battery pack and enables normal charging of the battery system. By analyzing the minimum number of battery packs that can be simultaneously pre-charged under the conditions that pre-charging is feasible and the main relay of the aircraft's high-voltage power grid is effectively closed, the minimum number of battery packs that can be opened simultaneously is taken as the effective number of openings. This can effectively reduce the time required for pre-charging and reduce the voltage drop of the pre-charging resistor in the pre-charging connection circuit. This effectively improves the voltage drop ratio and pre-charging speed of the aircraft's high-voltage power grid, allows for rapid and smooth closure of the main relay, effectively extends the battery system's service life, reduces operating costs, and enables normal charging of the battery system. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0016] Figure 1 This is a high-voltage system architecture diagram of the electric vertical takeoff and landing aircraft in Embodiment 1 of the present invention; Figure 2This is a flowchart of the battery system charging method for the electric vertical takeoff and landing aircraft in Embodiment 1 of the present invention; Figure 3 This is a flowchart of the output circuit detection process for the pre-charge connection circuit in Embodiment 1 of the present invention; Figure 4 This is a flowchart of the voltage discharge operation of the high-voltage power grid on the aircraft in Embodiment 1 of the present invention; Figure 5 This is a flowchart illustrating how, in Embodiment 1 of the present invention, the effective number of pre-charge connection circuits of the battery pack in the battery system is determined by calculation. Figure 6 This is a flowchart illustrating how, in Embodiment 1 of the present invention, the effective number of pre-charge connection circuits of the battery pack in the battery system is determined through an opening test. Figure 7 This is a battery system charging system architecture diagram of the electric vertical takeoff and landing aircraft in Embodiment 2 of the present invention. Detailed Implementation

[0017] 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, and 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.

[0018] In this invention, it should be understood that terms such as “comprising” or “having” are intended to indicate the presence of features, figures, steps, behaviors, components, portions or combinations thereof disclosed in this specification, and are not intended to exclude the possibility that one or more other features, figures, steps, behaviors, components, portions or combinations thereof are present or added.

[0019] It should also be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] Example 1 Embodiment 1 of the present invention provides a charging method for the battery system of an electric vertical takeoff and landing (EVTOL) aircraft. The battery system of the EVTOL aircraft includes several battery packs connected in parallel to the aircraft's onboard high-voltage power grid. The charging method includes: Establish an electrical connection between each battery pack in the battery system and the external charging port to form a pre-charge connection circuit for each battery pack; Perform output circuit detection on the pre-charge connection circuit; Initiate the voltage discharge action of the high-voltage power grid on the aircraft, and discharge the voltage of the high-voltage power grid on the aircraft to a preset threshold; Analyze the effective opening quantity of the pre-charge connection loop of the battery pack in the battery system based on a preset charging strategy, and initiate the pre-charge of the pre-charge connection loops with the effective opening quantity; After the pre-charge is completed, close the main relay of the high-voltage power grid on the aircraft, and the battery system executes the charging process.

[0021] The battery system charging method for an electric vertical takeoff and landing aircraft provided in this embodiment is mainly applied to the charging process of the battery system on the overall high-voltage system of an electric vertical takeoff and landing aircraft. As Figure 1 shown, Figure 1 Figure 1 shows the overall high-voltage system architecture diagram of the electric vertical takeoff and landing aircraft in Embodiment 1 of the present invention. The overall high-voltage system of the electric vertical takeoff and landing aircraft mainly includes the DC+ and DC- of the high-voltage power grid on the aircraft; and a battery system connected to the high-voltage power grid on the aircraft. The battery system includes a plurality of battery packs connected in parallel to the high-voltage power grid on the aircraft. This is because in current eVTOLs, in order to reduce complexity and improve safety, the battery system usually adopts a multi-battery-pack parallel connection method; it also includes high-voltage loads connected to the high-voltage power grid on the aircraft, including electric drives, DC-DC converters, etc. It was mentioned above that the existing high-voltage power grid on eVTOL aircraft usually does not have the function of controlled disconnection, and the high-voltage loads such as electric drives and DC-DC converters directly connected to the high-voltage power grid on eVTOL aircraft also do not have the function of controlled disconnection. Therefore, in the design of these high-voltage loads, in order to stabilize the voltage, protect power devices, and suppress noise, larger X capacitors and Y capacitors need to be introduced. Therefore, it also includes X capacitors and Y capacitors supporting the high-voltage loads, as well as insulation resistors to ensure insulation safety.

[0022] Furthermore, due to the power consumption of the high-voltage load upon power-up, and the energy absorption by the X and Y capacitors, the pre-charge current is lower than expected. This results in the pre-charge voltage failing to meet the preset time, leading to the inability to close the main relay and preventing normal charging of the battery system, thus affecting its safety and reliability. Existing charging solutions for electric vertical takeoff and landing (EVL) aircraft primarily involve separating the battery system from the aircraft's power system before charging it. However, this approach requires appropriate structural design on the aircraft to disconnect the battery system, and to ensure repeated charging, the reliability requirements of the high-voltage connectors need to be strengthened. This increases cost and repetitive operations, making it difficult to simultaneously meet the requirements of simplicity, convenience, economy, and high safety and reliability. Another solution is to simultaneously initiate pre-charging of more or even all battery packs in the battery system to ensure that the pre-charge current and pre-charge voltage meet the standards. However, this reduces the battery pack's lifespan and increases operating costs.

[0023] Therefore, this embodiment provides a battery system charging method for an electric vertical takeoff and landing (EVTOL) aircraft. By discharging the primary and secondary voltages of the aircraft's high-voltage power grid, the voltage of the high-voltage power grid is lower than the starting voltage of the high-voltage load, avoiding power consumption caused by the high-voltage load being powered on. This ensures that the pre-charging current and pre-charging voltage of the battery pack's pre-charging connection circuit meet the standards within a preset time, thereby ensuring the pre-charging operation of the battery pack and realizing the normal charging of the battery system. By analyzing the minimum number of battery packs that can be pre-charged simultaneously under the conditions that pre-charging is feasible and the main relay of the aircraft's high-voltage power grid is effectively closed, the minimum number of batteries that can be pre-charged simultaneously is taken as the effective number of batteries that can be pre-charged. This can effectively reduce the time required for pre-charging and reduce the voltage drop of the pre-charging resistor in the pre-charging connection circuit, thereby effectively improving the voltage drop ratio and pre-charging speed of the aircraft's high-voltage power grid, quickly and smoothly closing the main relay, effectively improving the working life of the battery system, reducing the cost of use, and realizing the normal charging operation of the battery system.

[0024] In one optional implementation of this embodiment, such as Figure 2 As shown, Figure 2 A flowchart illustrating the battery system charging method for an electric vertical takeoff and landing aircraft according to Embodiment 1 of the present invention is shown, including the following steps: S201. Establish an electrical connection between each battery pack in the battery system and the external charging port to form a pre-charge connection circuit corresponding to each battery pack; In an optional implementation of this embodiment, the battery system is the core component that provides power to the electric vertical takeoff and landing aircraft. The battery system includes several battery packs, which are connected in parallel to the aircraft's onboard high-voltage power grid to jointly supply power to the aircraft's power system and high-voltage loads. The parallel design of multiple battery packs aims to improve the system's energy density, power output capability, and redundancy safety. Each battery pack uses the same voltage platform and contains a separate Battery Management System (BMS) and Battery Disconnection Unit (BDU). It can independently control the connection and disconnection of the battery pack and communicate with the upper-level BMS or control computer.

[0025] Furthermore, the external charging port can be understood as the charging connection port of an external charging pile, through which the external charging pile provides power to the battery system in the aircraft.

[0026] Specifically, the external charging port described in this embodiment adopts the standard requirements commonly used in the electric vehicle industry.

[0027] In one optional implementation of this embodiment, a mechanical connection is established between the connection port of each battery pack in the battery system and the external charging port, and then an electrical connection is achieved, forming a pre-charge connection loop connecting each battery pack and the external charging port.

[0028] Furthermore, after forming the pre-charge connection circuit, the method further includes: The pre-charge connection circuit is subjected to pre-charge connection detection, which includes hardware matching, specification requirement matching, connection parameter configuration matching, authentication and direct connection confirmation between the battery system and the external charging port.

[0029] Specifically, after establishing a physical and electrical connection between the battery system and the external charging port of the electric vertical takeoff and landing (EVTOL) aircraft, and before actually starting the pre-charging process, the system proactively performs a series of pre-charging connection checks on the charging connection circuit. This check process aims to identify and eliminate potential connection problems before pre-charging begins, to avoid charging failures, equipment damage, or safety accidents caused by abnormal connections. Specifically, the hardware matching between the battery system and the external charging port verifies the compatibility of their physical and electrical interfaces, ensuring that hardware parameters such as the physical dimensions, pin definitions, voltage levels, and current carrying capacity of the connectors meet preset standards, preventing problems such as poor connections, excessive contact resistance, short circuits, or overloads caused by hardware incompatibility. For example, the type and specifications of the connector can be determined to be compatible with the battery system by detecting the level or impedance of specific identification pins on the charging connector; or, after the connection is established, the battery system or charging station can send a low-voltage test signal to detect the initial impedance or continuity of the circuit to confirm the integrity of the physical connection. Specification matching refers to verifying whether the charging connection loop conforms to predetermined industry standards, safety specifications, or communication protocol requirements, ensuring that the entire charging process is conducted in a safe, reliable, and compliant environment. This can be achieved through a communication protocol handshake between the charging pile and the battery system, exchanging and comparing information on the charging specification versions they support to confirm that both parties support compatible specifications; or by the charging controller checking the configuration information sent by the charging pile or battery system, such as maximum charging voltage and maximum charging current, to ensure that these parameters are within the allowable range of the battery system or charging pile. Connection parameter configuration matching aims to verify whether the configuration of various electrical parameters involved in the charging connection loop is consistent and reasonable, ensuring that key parameters such as charging voltage, charging current, communication rate, and protocol version are consistent between the battery system and the external charging port. For example, the charging pile and battery system can negotiate and confirm charging parameters through a communication link to ensure that the parameter configurations of both parties are consistent; or after receiving a charging request from the charging pile, the battery management system (BMS) compares the parameters in the request with its own set parameters. If there are inconsistencies or exceed the safety range, charging is refused or adjustments are requested. Authentication and direct connection confirmation refers to verifying the legitimacy of the connection and directly confirming the connection status to prevent unauthorized charging devices from accessing the system and ensure the security of the charging process. This can be achieved through digital certificates, key exchange, or challenge-response mechanisms for identity authentication between the charging station and the battery system; or, after completing hardware, specification, and parameter matching, the battery system or charging station sends a final connection confirmation signal and waits for a response from the other party to ensure that the connection is fully established and ready.

[0030] Furthermore, the external charging port in this embodiment complies with the specifications of GB / T 20234.3 (DC interface), GB / T18487.5 (charging system) and GB / T 27930.2 (communication protocol).

[0031] S202. Perform output circuit detection on the pre-charge connection circuit; In one optional implementation of this embodiment, such as Figure 3 As shown, Figure 3 The flowchart illustrating the output circuit detection process for the pre-charge connection circuit in Embodiment 1 of the present invention is shown, including the following steps: S301. An output circuit detection command is triggered through an external charging port, and all battery packs in the battery system respond to the output circuit detection command and feed back initial state information; In one optional implementation of this embodiment, a start-up circuit detection signal is sent to the battery system via the interface through which the electric vertical takeoff and landing (EVTOL) aircraft's battery system is electrically connected to an external charging device. This command can be transmitted via a charging pile or ground power supply to the external charging port, and this signal is recognized as a detection command by the battery management system (BMS). Alternatively, a predefined detection command frame can be sent via a specific pin level change of the charging port or a communication protocol (such as CAN, Ethernet, etc.).

[0032] Furthermore, all battery packs in the battery system respond to the output circuit detection command, execute preset response actions, and send their current operating status, health status, voltage, temperature, and other data back to the control unit. Upon receiving the command, the battery management unit (BMU) within each battery pack can collect its own voltage, current, temperature, and other data through internal sensors, and package and send this data to the battery system main controller (BCU) via a communication bus (such as a CAN bus). Alternatively, the battery pack can pre-store a set of initial state parameters, and upon receiving the command, directly feed back these pre-stored parameters or real-time acquired brief statuses (such as "ready" or "fault") to the external control device via a dedicated signal line or communication interface.

[0033] S302. Perform short circuit detection, insulation detection, and contactor adhesion detection on the pre-charge connection circuit, and provide real-time feedback on the detection status; In one optional implementation of this embodiment, short circuit detection can be determined by applying a small current to the circuit and measuring the voltage drop, or by measuring the equivalent resistance of the circuit. Insulation detection can be determined by applying a high voltage and measuring the leakage current, or by measuring the insulation resistance between the circuit and ground. Contactor sticking detection can be determined by measuring the voltage at both ends of the contactor or the current in the circuit after the contactor disconnect command is issued. If there is still voltage or current, it is determined to be sticking.

[0034] Furthermore, short-circuit detection is used to check for abnormal low-impedance connections in the circuit, insulation detection is used to check for leakage between the circuit and ground or other circuits, and contactor sticking detection is used to check whether the contactor controlling the on / off of the circuit cannot disconnect normally due to a fault.

[0035] S303. After the short circuit detection, insulation detection and contactor adhesion detection are passed, proceed to the next step of voltage discharge.

[0036] In one optional implementation of this embodiment, after the short circuit detection, insulation detection and contactor adhesion detection items are all passed, the next step of voltage discharge operation is performed.

[0037] S203. Initiate the voltage discharge action of the high-voltage power grid on the aircraft to discharge the voltage of the high-voltage power grid on the aircraft to a preset threshold. In one optional implementation of this embodiment, such as Figure 4 As shown, Figure 4 The following is a flowchart illustrating the voltage discharge operation of the high-voltage power grid on an aircraft according to Embodiment 1 of the present invention, including the following steps: S401. Initiate a voltage discharge action on the high-voltage power grid on the aircraft to discharge the voltage of the high-voltage power grid on the aircraft to a first preset threshold. In one optional implementation of this embodiment, a voltage discharge action is initiated on the high-voltage power grid of the aircraft to discharge the voltage of the high-voltage power grid to a first preset threshold, thereby initially reducing the voltage level of the high-voltage power grid and reducing the risk of accidental activation of the high-voltage load.

[0038] Specifically, in the application scenario of this embodiment, the first preset threshold should be set to be lower than the external voltage value of the pre-charge connection circuit contactor, with a value of 60V.

[0039] S402. Extract the starting voltage data of the high-voltage load connected to the high-voltage power grid on the aircraft. In one optional implementation of this embodiment, the inherent electrical characteristic parameters of the high-voltage load are obtained to provide a key reference for subsequent accurate voltage discharge. This can be obtained by querying the preset high-voltage load parameter database stored in the battery management system (BMS) or the aircraft control unit (FCU), or by directly measuring and determining the minimum starting voltage of the high-voltage load by performing a low-voltage test on the high-voltage load after the charging connection is established.

[0040] S403. Initiate the secondary voltage discharge action of the high-voltage power grid on the aircraft, so that the voltage of the high-voltage power grid on the aircraft is discharged from the first preset threshold to the second preset threshold, the second preset threshold being less than the starting voltage data of the high-voltage load.

[0041] In one optional implementation of this embodiment, a secondary voltage discharge action is initiated on the high-voltage power grid on the aircraft, causing the voltage of the high-voltage power grid on the aircraft to be discharged from a first preset threshold to a second preset threshold. The second preset threshold is less than the starting voltage data of the high-voltage load, further precisely reducing the voltage and ensuring that the voltage of the high-voltage power grid is completely lower than the starting voltage of the high-voltage load. This completely avoids the high-voltage load being accidentally activated during the pre-charging stage, thereby avoiding the power consumption caused by the power-on of the high-voltage load. It also ensures that the pre-charging current and pre-charging voltage of the pre-charging connection circuit of the battery pack meet the standards within a preset time, thereby ensuring the pre-charging action of the battery pack and realizing the normal charging of the battery system.

[0042] Furthermore, the initiation of the secondary voltage discharge action to the high-voltage power grid on the aircraft can be achieved through the following operations: Activate the active discharge function of the high-voltage load; Adjust the circuit parameters and discharge threshold of the discharge circuit of the high-voltage power grid on the aircraft. An external discharge circuit is connected to the high-voltage power grid on the aircraft.

[0043] S204. Analyze the effective number of pre-charge connection circuits of the battery pack in the battery system based on the preset charging strategy, and start the pre-charge of the effective number of pre-charge connection circuits. In an optional implementation of this embodiment, the effective number of precharge connection circuits of the battery pack in the battery system is determined by calculation, and / or by an activation test.

[0044] Specifically, the effective number of pre-charge connection circuits of the battery pack in the battery system can be obtained through data calculation, specific testing, or preferably both, with the results mutually verified.

[0045] In one optional implementation of this embodiment, such as Figure 5 As shown, Figure 5 This invention illustrates a flowchart of a calculation method for determining the effective number of pre-charge connection circuits of the battery pack in the battery system according to Embodiment 1 of the present invention, including the following steps: S501. Obtain the pre-charge resistance value of a single battery pack and the equivalent capacitance values ​​of X capacitor and Y capacitor in the high-voltage load of the high-voltage power grid on the aircraft. In one optional implementation of this embodiment, each battery pack in the battery system has the same specifications, so it can be assumed that each battery pack has the same voltage and the same pre-charge resistance value.

[0046] S502. Based on the capacitor charging characteristic formula, establish a standard first-order linear differential equation, substitute the pre-charging resistance value of the single battery pack and the equivalent capacitance values ​​of X capacitor and Y capacitor in the high-voltage load of the high-voltage grid on the aircraft into the standard first-order linear differential equation, and obtain the pre-charging time constant and voltage division ratio corresponding to different activation numbers. In one optional implementation of this embodiment, the analysis process is as follows: When a capacitor is charging, the capacitor charging characteristic formula, that is, the relationship between its voltage and charging current, is as follows:

[0047] In the formula This is the capacitance value.

[0048] Substituting the battery pack voltage, pre-charge resistance value, and the equivalent capacitance values ​​of capacitors X and Y in the high-voltage load of the aircraft's high-voltage power grid, the following formula is obtained:

[0049]

[0050] In the formula, The voltage on the high-voltage power grid on the aircraft. R represents the battery pack voltage, and R represents the pre-charge resistance value of the battery pack. This is the equivalent capacitance value after all X and Y capacitors are connected in series and parallel in the high-voltage load of the high-voltage power grid on the aircraft.

[0051] Formula (3) is a standard first-order linear differential equation established based on the capacitor charging characteristic formula, and its general solution is:

[0052] When pre-charging starts from 0V

[0053] In the formula, , is the time constant of the capacitor charging circuit when n pre-charging resistors are turned on simultaneously.

[0054] Furthermore, the expression for the time constant shows that the more battery packs that can be precharged simultaneously (the larger n is), the faster the precharge (τ decreases) and the higher the precharge ratio (the equivalent precharge resistance decreases). Therefore, the appropriate number of batteries that can be precharged simultaneously (the value of n) can be determined according to the requirements (precharge duration, precharge ratio).

[0055] S503. Based on the preset precharge duration threshold and voltage compliance ratio, match the precharge time constant and voltage division ratio corresponding to the different opening quantities, and select the minimum number of precharge connection circuits that meet the precharge requirements as the effective opening quantity.

[0056] In an optional implementation of this embodiment, the minimum number of precharge connection loops that meet the precharge requirements is selected as the effective number of loops through the calculation in step S502.

[0057] In one optional implementation of this embodiment, such as Figure 6 As shown, Figure 6 This invention illustrates a flowchart of determining the effective number of pre-charge connection circuits of the battery pack in the battery system through an activation test, according to Embodiment 1 of the present invention. The flowchart includes the following steps: S601. In the initial state, open the pre-charge connection circuit of all battery packs to verify the feasibility of pre-charging at this time and the closing effectiveness of the main relay of the high-voltage grid on the aircraft. In one optional implementation of this embodiment, the precharge connection circuits of all battery packs are opened to ensure that the test starts from the most possible configuration and to verify whether the basic functions can be realized normally when all battery packs participate in precharge. Specifically, by monitoring the voltage and current changes of the precharge circuit, it is determined whether the precharge voltage can reach the preset threshold within a specified time, and the main relay is closed at an attempt to observe whether it can close normally and remain stable.

[0058] Here, we consider taking an extreme case first to test whether the pre-charging feasibility and the closing effectiveness of the main relay of the high-voltage power grid on the aircraft are met when the maximum number of pre-charging connection circuits are opened. This will establish a benchmark for subsequent gradual adjustments. Under normal circumstances, activating the precharge connection circuits of all battery packs simultaneously can satisfy the feasibility of precharge and the closing effectiveness of the main relay. However, this will reduce the lifespan of all battery packs that have activated precharge. Therefore, in the subsequent adjustment strategy, we can consider activating fewer precharge connection circuits to achieve both precharge feasibility and the closing effectiveness of the main relay.

[0059] S602. Gradually reduce the number of pre-charge connection circuits opened in the battery pack, and verify the feasibility of pre-charge and the closing effectiveness of the main relay simultaneously after each adjustment. In one optional implementation of this embodiment, the number of precharge connection circuits of the battery pack is gradually reduced. By reducing the number of precharge connection circuits of the battery pack one by one, the precharge effect under different numbers of circuits can be dynamically monitored to ensure that each adjustment meets the requirements and avoid reducing too many circuits at once, which would cause precharge failure.

[0060] S603. Record the minimum number of precharge connection circuits that are opened to satisfy the feasibility of precharge and the closing validity of the main relay, as the effective number of openings.

[0061] In one optional implementation of this embodiment, after reducing the number of precharge connection circuits opened one by one, when the number of precharge connection circuits opened for a certain battery pack is opened for precharge, if the precharge feasibility and the closing validity of the main relay are no longer satisfied, then the number of openings at the previous moment, i.e., the number of openings at this moment plus one, is locked as the valid number of openings.

[0062] Furthermore, this process ensures that battery pack resources are utilized to the maximum extent while meeting pre-charge requirements, thereby improving the efficiency and reliability of the pre-charge process. It also allows for achieving the goal by activating as few battery packs as possible during pre-charge. This step-by-step testing mechanism can systematically identify and lock the optimal number of activations, optimizing the charging performance of the battery system. It effectively avoids situations in traditional methods where high-voltage loads and capacitor energy absorption lead to lower-than-expected pre-charge current and substandard pre-charge voltage, preventing the main relay from closing.

[0063] The above methods determine the effective number of pre-charge connection circuits in the battery pack of the battery system through calculation and activation testing, respectively. These two methods can be used individually or in combination. This flexibility allows for the selection of the most suitable method based on the actual application scenario, available resources, and requirements for accuracy and efficiency. For example, in the initial design phase, emphasis can be placed on calculation, with activation testing conducted before actual deployment, or a preliminary judgment can be made based on the calculation results during operation, followed by fine-tuning through small-scale testing.

[0064] In an optional implementation of this embodiment, the pre-activation of the effective number of pre-charge connection circuits includes: When precharging the precharge connection circuit corresponding to the effective number of activations, precharging of all precharge connection circuits corresponding to the effective number of activations must be activated simultaneously.

[0065] Specifically, in practical applications, if the activation method does not activate an effective number of battery packs simultaneously, it may lead to uneven distribution of pre-charge current, prolonging the pre-charge time or causing inconsistent voltage rise, affecting the pre-charge effect and the closure reliability of the main relay. Therefore, the pre-charging of the pre-charging connection circuits of all battery packs corresponding to the effective number of activations needs to be activated simultaneously. This synchronous start mechanism ensures that the pre-charging current can flow evenly from all effective battery packs to the aircraft's high-voltage power grid, avoiding problems such as uneven current distribution, local voltage fluctuations, or prolonged pre-charging time caused by asynchronous start.

[0066] S205. After pre-charging is completed, the main relay of the high-voltage power grid on the aircraft is closed, and the battery system executes the charging process.

[0067] In one optional implementation of this embodiment, after all battery packs have completed pre-charging, the main relay of the aircraft's high-voltage power grid is closed, and the battery system executes a constant-voltage charging process. This step marks the end of the pre-charging phase and the beginning of the main charging phase. For example, when the pre-charging voltage of all battery packs reaches a preset target value, a simple voltage comparator can detect that the voltage of all battery packs has met the condition, and then send a closing command to the main relay. After the main relay is closed, the charging equipment will charge the battery system at a constant voltage until the battery is fully charged.

[0068] In summary, Embodiment 1 of this invention provides a battery system charging method for an electric vertical takeoff and landing (EVTOL) aircraft. By discharging the primary and secondary voltages of the aircraft's high-voltage power grid, the voltage of the high-voltage power grid is lower than the starting voltage of the high-voltage load, avoiding power consumption caused by triggering the high-voltage load. This ensures that the pre-charging current and pre-charging voltage of the battery pack's pre-charging connection circuit meet the standards within a preset time, thereby ensuring the pre-charging operation of the battery pack and realizing the normal charging of the battery system. By analyzing the minimum number of battery packs that can be pre-charged simultaneously under the conditions that pre-charging is feasible and the main relay of the aircraft's high-voltage power grid is effectively closed, the minimum number of open circuits is taken as the effective number of open circuits. This can effectively reduce the time required for pre-charging and the voltage division of the pre-charging resistor in the pre-charging connection circuit, thereby effectively improving the voltage division ratio and pre-charging speed of the aircraft's high-voltage power grid, quickly and smoothly closing the main relay, effectively improving the working life of the battery system, reducing the operating cost, and realizing the normal charging operation of the battery system.

[0069] Example 2 Embodiment 2 of the present invention provides a battery system charging system for an electric vertical takeoff and landing (EVTOL) aircraft. The charging system is used to implement the battery system charging method for the EVTOL aircraft described in Embodiment 1. The charging system includes a pre-charge connection circuit connection module, an output circuit detection module, a voltage discharge action module, a pre-charge activation module, and a charging module.

[0070] In one optional implementation of this embodiment, such as Figure 7 As shown, Figure 7 The diagram shows the battery system charging system architecture of the electric vertical takeoff and landing aircraft according to Embodiment 2 of the present invention, which includes the following modules: The precharge connection circuit connection module 10 is used to establish an electrical connection between each battery pack in the battery system and an external charging port, forming a precharge connection circuit corresponding to each battery pack. In an optional implementation of this embodiment, after forming the pre-charged connection loop, the method further includes: The pre-charge connection circuit is subjected to pre-charge connection detection, which includes hardware matching, specification requirement matching, connection parameter configuration matching, authentication and direct connection confirmation between the battery system and the external charging port.

[0071] Output circuit detection module 20, which is used to perform output circuit detection on the precharge connection circuit; In an optional implementation of this embodiment, the step of performing output circuit detection on the precharge connection circuit includes: An output circuit detection command is triggered by an external charging port, and all battery packs in the battery system respond to the output circuit detection command and feed back initial state information. Short circuit detection, insulation detection, and contactor adhesion detection are performed on the pre-charge connection circuit, and the detection status is fed back in real time. After the short circuit detection, insulation detection, and contactor adhesion detection are passed, the next step of voltage discharge operation is initiated.

[0072] Voltage discharge action module 30, the voltage discharge action module 30 is used to initiate voltage discharge action on the high voltage grid on the aircraft, so that the voltage of the high voltage grid on the aircraft is discharged to a preset threshold. In an optional implementation of this embodiment, initiating the voltage discharge action on the high-voltage power grid of the aircraft, causing the voltage of the high-voltage power grid on the aircraft to discharge to a preset threshold, includes: Initiate a voltage discharge action on the high-voltage power grid on the aircraft to discharge the voltage of the high-voltage power grid on the aircraft to a first preset threshold. Extract the start-up voltage data of the high-voltage load connected to the high-voltage power grid on the aircraft. Initiate a secondary voltage discharge action on the high-voltage power grid on the aircraft, causing the voltage of the high-voltage power grid on the aircraft to be discharged from a first preset threshold to a second preset threshold, where the second preset threshold is less than the starting voltage data of the high-voltage load.

[0073] In an optional implementation of this embodiment, the initiation of the secondary voltage discharge action to the high-voltage power grid on the aircraft includes: Activate the active discharge function of the high-voltage load; Adjust the circuit parameters and discharge threshold of the discharge circuit of the high-voltage power grid on the aircraft. An external discharge circuit is connected to the high-voltage power grid on the aircraft.

[0074] The precharge activation module 40 is used to analyze the effective number of precharge connection circuits of the battery pack in the battery system based on a preset charging strategy, and activate the precharge of the effective number of precharge connection circuits. In an optional implementation of this embodiment, the step of analyzing the number of effectively activated pre-charge connection circuits of the battery pack in the battery system based on a preset charging strategy includes: The effective number of precharge connection circuits of the battery pack in the battery system is determined by calculation, and / or by activation test.

[0075] In an optional implementation of this embodiment, determining the effective number of pre-charge connection circuits of the battery pack in the battery system by calculation includes: Obtain the pre-charge resistance value of a single battery pack and the equivalent capacitance values ​​of X capacitor and Y capacitor in the high-voltage load of the high-voltage power grid on the aircraft. A standard first-order linear differential equation is established based on the capacitor charging characteristic formula. The pre-charging resistance value of the single battery pack and the equivalent capacitance values ​​of X capacitor and Y capacitor in the high-voltage load of the high-voltage grid on the aircraft are substituted into the standard first-order linear differential equation to obtain the pre-charging time constant and voltage division ratio corresponding to different activation numbers. Based on the preset precharge duration threshold and voltage compliance ratio, the precharge time constant and voltage division ratio corresponding to the different activation quantities are matched to select the minimum number of precharge connection circuits that meet the precharge requirements as the effective activation quantity.

[0076] In an optional implementation of this embodiment, determining the number of validly activated pre-charge connection circuits of the battery pack in the battery system through an activation test includes: In the initial state, the pre-charge connection circuits of all battery packs are opened to verify the feasibility of pre-charging at this time and the closing effectiveness of the main relay of the high-voltage power grid on the aircraft. Gradually reduce the number of pre-charge connection circuits opened in the battery pack, and verify the feasibility of pre-charging and the closing effectiveness of the main relay simultaneously after each adjustment; Record the minimum number of precharge connection circuits that must be opened to satisfy both precharge feasibility and the closing validity of the main relay, as the effective number of openings.

[0077] In an optional implementation of this embodiment, sequentially activating the precharge connection circuits of all battery packs and initiating precharge based on the effective activation count includes: When precharging is initiated for the precharge connection circuit of the battery pack corresponding to the effective number of activations, precharging of the precharge connection circuits of all battery packs corresponding to the effective number of activations must be initiated simultaneously.

[0078] The charging module 50 is used to close the main relay of the high-voltage power grid on the aircraft after pre-charging is completed, and the battery system executes the charging process.

[0079] In summary, Embodiment 2 of the present invention provides a battery system charging system for an electric vertical takeoff and landing (EVTOL) aircraft. This charging system implements the battery system charging method for the EVTOL aircraft described in Embodiment 1. By discharging the primary and secondary voltages of the aircraft's high-voltage power grid, the voltage of the high-voltage power grid is lower than the starting voltage of the high-voltage load, avoiding power consumption caused by triggering the high-voltage load. This ensures that the pre-charging current and pre-charging voltage of the battery pack's pre-charging connection circuit meet the standards within a preset time, thereby ensuring the pre-charging operation of the battery pack and achieving normal charging of the battery system. By analyzing the minimum number of battery packs simultaneously pre-charging when pre-charging is feasible and the main relay of the aircraft's high-voltage power grid is effectively closed, the minimum number of open switches is used as the effective number of open switches. This maximizes the reduction of pre-charging time and the reduction of voltage division in the pre-charging connection circuit, thereby effectively improving the voltage division ratio and pre-charging speed of the aircraft's high-voltage power grid, quickly and smoothly closing the main relay, effectively improving the battery system's service life, reducing operating costs, and achieving normal charging of the battery system.

[0080] The above provides a detailed description of the battery system charging method and charging system for an electric vertical take-off and landing aircraft provided by the present invention. Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, which may include: read-only memory (ROM), random access memory (RAM), disk or optical disk, etc.

[0081] Furthermore, the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for charging the battery system of an electric vertical takeoff and landing aircraft, characterized in that, The battery system of the electric vertical takeoff and landing aircraft includes several battery packs connected in parallel to the aircraft's onboard high-voltage power grid, and the charging method includes: Establish an electrical connection between each battery pack in the battery system and the external charging port to form a pre-charge connection circuit for each battery pack; Perform output circuit detection on the pre-charge connection circuit; Initiate voltage discharge to the high-voltage power grid on the aircraft, causing the voltage of the high-voltage power grid on the aircraft to discharge to a preset threshold. The step of initiating a voltage discharge operation on the high-voltage power grid of the aircraft, discharging the voltage of the high-voltage power grid to a preset threshold, includes: initiating a primary voltage discharge operation on the high-voltage power grid of the aircraft, discharging the voltage of the high-voltage power grid to a first preset threshold; extracting the starting voltage data of the high-voltage load connected to the high-voltage power grid of the aircraft; and initiating a secondary voltage discharge operation on the high-voltage power grid of the aircraft, discharging the voltage of the high-voltage power grid from the first preset threshold to a second preset threshold, wherein the second preset threshold is less than the starting voltage data of the high-voltage load. The initiation of the secondary voltage discharge action on the high-voltage power grid of the aircraft includes: activating the active discharge function of the high-voltage load; adjusting the circuit parameters and discharge threshold of the discharge circuit of the high-voltage power grid of the aircraft; and connecting an external discharge circuit to the high-voltage power grid of the aircraft. Based on the preset charging strategy, the effective number of pre-charge connection circuits of the battery pack in the battery system is analyzed, and the pre-charge of the effective number of pre-charge connection circuits is started. After pre-charging is completed, the main relay of the high-voltage power grid on the aircraft is closed, and the battery system executes the charging process.

2. The battery system charging method for an electric vertical takeoff and landing aircraft as described in claim 1, characterized in that, The step of performing output circuit detection on the pre-charged connection circuit includes: An output circuit detection command is triggered by an external charging port, and all battery packs in the battery system respond to the output circuit detection command and feed back initial state information. Short circuit detection, insulation detection, and contactor adhesion detection are performed on the pre-charge connection circuit, and the detection status is fed back in real time. After the short circuit detection, insulation detection, and contactor adhesion detection are passed, the next step of voltage discharge operation is initiated.

3. The battery system charging method for an electric vertical takeoff and landing aircraft as described in claim 1, characterized in that, The effective number of pre-charge connection circuits of the battery pack in the battery system that are analyzed based on a preset charging strategy includes: The effective number of precharge connection circuits of the battery pack in the battery system is determined by calculation, and / or by activation test.

4. The battery system charging method for an electric vertical takeoff and landing aircraft as described in claim 3, characterized in that, The calculation of determining the effective number of precharge connection circuits of the battery pack in the battery system includes: Obtain the pre-charge resistance value of a single battery pack and the equivalent capacitance values ​​of X capacitor and Y capacitor in the high-voltage load of the high-voltage power grid on the aircraft. A standard first-order linear differential equation is established based on the capacitor charging characteristic formula. The pre-charging resistance value of the single battery pack and the equivalent capacitance values ​​of X capacitor and Y capacitor in the high-voltage load of the high-voltage grid on the aircraft are substituted into the standard first-order linear differential equation to obtain the pre-charging time constant and voltage division ratio corresponding to different activation numbers. Based on the preset precharge duration threshold and voltage compliance ratio, the precharge time constant and voltage division ratio corresponding to the different activation quantities are matched to select the minimum number of precharge connection circuits that meet the precharge requirements as the effective activation quantity.

5. The battery system charging method for an electric vertical takeoff and landing aircraft as described in claim 3, characterized in that, The determination of the effective number of pre-charge connection circuits of the battery pack in the battery system through the opening test includes: In the initial state, the pre-charge connection circuits of all battery packs are opened to verify the feasibility of pre-charging at this time and the closing effectiveness of the main relay of the high-voltage power grid on the aircraft. Gradually reduce the number of pre-charge connection circuits opened in the battery pack, and verify the feasibility of pre-charging and the closing effectiveness of the main relay simultaneously after each adjustment; Record the minimum number of precharge connection circuits that must be opened to satisfy both precharge feasibility and the closing validity of the main relay, as the effective number of openings.

6. The battery system charging method for an electric vertical takeoff and landing aircraft as described in claim 1, characterized in that, The pre-charging of the pre-charge connection circuits that are activated in the effective number of activations includes: When precharging the precharge connection circuit corresponding to the effective number of activations, precharging of all precharge connection circuits corresponding to the effective number of activations must be activated simultaneously.

7. The battery system charging method for an electric vertical takeoff and landing aircraft as described in claim 1, characterized in that, After forming the pre-charged connection loop, the method further includes: The pre-charge connection circuit is subjected to pre-charge connection detection, which includes hardware matching, specification requirement matching, connection parameter configuration matching, authentication and direct connection confirmation between the battery system and the external charging port.

8. A battery charging system for an electric vertical takeoff and landing aircraft, characterized in that, The charging system is used to implement the battery system charging method of the electric vertical takeoff and landing aircraft according to any one of claims 1-7, and the charging system includes: A pre-charge connection circuit connection module is used to establish an electrical connection between each battery pack in the battery system and an external charging port, forming a pre-charge connection circuit corresponding to each battery pack. An output circuit detection module is used to perform output circuit detection on the precharge connection circuit. A voltage discharge action module is used to initiate a voltage discharge action on the high-voltage power grid on the aircraft, so that the voltage of the high-voltage power grid on the aircraft is discharged to a preset threshold. The step of initiating a voltage discharge operation on the high-voltage power grid of the aircraft, discharging the voltage of the high-voltage power grid to a preset threshold, includes: initiating a primary voltage discharge operation on the high-voltage power grid of the aircraft, discharging the voltage of the high-voltage power grid to a first preset threshold; extracting the starting voltage data of the high-voltage load connected to the high-voltage power grid of the aircraft; and initiating a secondary voltage discharge operation on the high-voltage power grid of the aircraft, discharging the voltage of the high-voltage power grid from the first preset threshold to a second preset threshold, wherein the second preset threshold is less than the starting voltage data of the high-voltage load. The initiation of the secondary voltage discharge action on the high-voltage power grid of the aircraft includes: activating the active discharge function of the high-voltage load; adjusting the circuit parameters and discharge threshold of the discharge circuit of the high-voltage power grid of the aircraft; and connecting an external discharge circuit to the high-voltage power grid of the aircraft. A precharge activation module is used to analyze the effective number of precharge connection circuits of the battery pack in the battery system based on a preset charging strategy, and activate the precharge of the effective number of precharge connection circuits. The charging module is used to close the main relay of the high-voltage power grid on the aircraft after pre-charging is completed, and the battery system executes the charging process.

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