A method for on-orbit fault diagnosis of lithium-ion batteries in low-orbit satellites

Abstract

This application provides a method for diagnosing on-orbit faults in lithium-ion batteries for low-orbit satellites, suitable for rapidly locating charging faults in lithium-ion batteries in the energy system of small satellites during on-orbit operation. By comprehensively logically judging the satellite's orbital phase and key characteristic parameters of the lithium-ion battery, such as the charging current, current charge level, current voltage, and charging current setting level, the method diagnoses different charging faults that may occur in lithium-ion batteries on-orbit and affect the function of the energy system and the safety of the entire satellite. This method reserves sufficient time for subsequent emergency response or ground intervention in the satellite, significantly improving the reliability and safety of the satellite's energy system.

Description

Technical Field

[0001] The present application belongs to the field of satellite energy system engineering, and generally relates to a method for diagnosing on-orbit faults of lithium-ion batteries in low-orbit satellites, which is suitable for quickly locating charging faults of lithium-ion batteries in the energy system of small satellites when they are in orbit. Background Art

[0002] As a key satellite system, the satellite energy system plays the important role of generating, regulating, storing, and distributing electrical energy throughout the satellite. It provides a lifecycle energy source for the satellite platform and onboard payloads, directly impacting the safety of the satellite's in-orbit operation. The satellite energy system primarily consists of three components: a solar array, a battery pack, and a power controller. During the Earth's shadow, the battery pack discharges to power the entire satellite. During the illuminated period, the solar array prioritizes powering the onboard loads, and any remaining energy is used to charge the battery pack. Compared to other types of space batteries, lithium-ion batteries, with their high energy density, long cycle life, and low self-discharge current, are currently widely used as the primary energy storage power source on medium and low-orbit spacecraft.

[0003] While lithium-ion batteries offer numerous advantages, they also have significant disadvantages. Excessive electrolyte decomposition can increase internal temperature and pressure within the battery, leading to safety issues while in orbit. Therefore, overcharging of lithium-ion batteries is strictly prohibited. On the other hand, undercharging a lithium-ion battery can also cause an imbalance in the satellite's on-orbit energy, potentially impacting the failure of the satellite's on-orbit mission. The use of lithium-ion batteries on small, low-orbit satellites is characterized by their independence from other satellites. For example, low-orbit satellites have relatively short orbital periods, corresponding to more charge and discharge cycles for lithium batteries. As on-orbit time increases, the probability of charging failures increases due to the lithium-ion battery's high sensitivity to overcharging and the multiple on-orbit charge and discharge cycles experienced by low-orbit satellites.

[0004] In the past, the diagnostic strategy for lithium-ion battery charging anomalies on low-orbit small satellites was limited to extracting direct characteristic parameters (such as charging current), and did not fully utilize the satellite's on-orbit related information or some potential symptom data for comprehensive analysis. Therefore, the existing charging fault diagnosis strategy has the following main problems:

[0005] (1) The accuracy and reliability of deep fault diagnosis are slightly lacking;

[0006] (2) The key characteristic parameters for judging charging faults are single and limited to the battery pack indicators themselves, such as charging current and battery voltage. However, due to the relatively slow change of the actual on-track battery voltage, fault diagnosis and treatment cannot be carried out in a timely and effective manner.

[0007] (3) The fault judgment criteria and logic strategies did not take into account the system or even the entire satellite, and ignored the relationship between other equipment in the system and battery charging abnormalities. Summary of the Invention

[0008] Aiming at the problems in the currently commonly used on-orbit abnormal charging fault diagnosis strategy of lithium-ion batteries, such as the single extraction of judgment feature parameters, which leads to insufficient accuracy and real-time performance of on-orbit abnormal charging diagnosis of lithium-ion batteries, a low-orbit satellite lithium-ion battery on-orbit fault diagnosis method is proposed, which can quickly diagnose on-orbit faults of low-orbit satellite lithium-ion batteries.

[0009] The present application provides a method for on-orbit fault diagnosis of lithium-ion batteries in low-orbit satellites, comprising:

[0010] S1: Determine whether the satellite is in the illumination period. If it is, proceed to step S2;

[0011] S2: Determine whether the battery charging current is 0: If the charging current is equal to 0, proceed to step S3; if not, proceed to step S5;

[0012] S3: Determine whether the following first and second conditions are met at the same time: If both conditions are met, proceed to step S4; if both conditions are not met, it means that there is no fault in charging at this time, and the process ends directly.

[0013] The first condition: the current battery capacity is less than the rated battery capacity;

[0014] The second condition: the solar cell array current is greater than the load current.

[0015] S4: Determine whether the battery charging current setting level is equal to 0: if it is equal to 0, it is determined to be a third type of fault; if it is not equal to 0, it is determined to be a first type of fault;

[0016] S5: Determine whether the current battery capacity is equal to the rated battery capacity: if they are equal, proceed to step S8; if they are not equal, proceed to step S6;

[0017] S6: Determine whether the following third condition, fourth condition and fifth condition are met at the same time: If they are met at the same time, proceed to step S7; if they are not met at the same time, it means that there is no fault in charging at this time, and the process ends directly.

[0018] The third condition: the current battery voltage is less than the constant current constant voltage reference voltage value;

[0019] The fourth condition: the difference between the solar cell array current and the load current is greater than the charging current;

[0020] Fifth condition: the battery charging current is less than the charging constant current stage current;

[0021] S7: Determine whether the charging current setting level is equal to the constant current section setting voltage value: if they are not equal, it is determined to be a third type fault; if they are equal, it is determined to be a second type fault;

[0022] S8: Determine whether the battery charging current is greater than the charge termination current: If the charging current is greater than the charge termination current, proceed to step S9; if the charging current is not greater than the charge termination current, it means that there is no fault in charging at this time, and the process ends directly.

[0023] S9: Determine whether the charging current setting level is equal to 0: If it is equal to 0, it is determined to be a fourth type of fault; if it is not equal to 0, it is determined to be a third type of fault.

[0024] According to at least one embodiment of the present application, the first type of fault is an abnormal fault in the charging circuit, and the battery cannot be charged.

[0025] According to at least one embodiment of the present application, the method further includes: when it is determined to be a first type fault, sending a charging circuit connection instruction to resolve the fault.

[0026] According to at least one embodiment of the present application, the second type of fault is an abnormal fault in the fast charging circuit, and charging cannot be terminated.

[0027] According to at least one embodiment of the present application, the method further includes: when it is determined to be a second type of fault, sending a fast charging switch turning on instruction to resolve the fault.

[0028] According to at least one embodiment of the present application, the third type of fault is an abnormal D / A output fault of the lower computer.

[0029] According to at least one embodiment of the present application, the method further includes: when it is determined to be a third type of fault, the satellite service sends a power supply lower-level machine a power cut-off instruction to resolve the fault.

[0030] According to at least one embodiment of the present application, the fourth type of fault is a charging failure termination fault.

[0031] According to at least one embodiment of the present application, the method further includes: when it is determined to be a fourth type of fault, sending a fast charging switch and BCR circuit disconnection instruction to resolve the fault.

[0032] According to at least one embodiment of the present application, the constant current to constant voltage reference voltage value and the current in the constant current section of charging are preset values.

[0033] The advantages of the present invention compared with the prior art are:

[0034] (1) The method of the present invention can significantly improve the accuracy and reliability of deep-level charging fault diagnosis.

[0035] (2) The method of the present invention changes the existing situation of using relatively single key characteristic parameters for fault diagnosis. The judgment criteria and logic strategies are not limited to the battery group indicators themselves, but are comprehensively considered at the system and even the entire satellite level, thereby improving the reliability of charging fault diagnosis.

[0036] (3) The method of the present invention also takes into account the important role of solar cell array current in battery pack charging fault diagnosis, and uses the solar cell array current as one of the bases for judging whether the onboard battery pack is in abnormal charging. Compared with the existing method, the influence of the equipment other than the battery pack in the satellite energy subsystem on the battery pack temperature is taken into account, and the battery pack fault diagnosis is performed from the perspective of the entire system, which greatly improves the stability and safety of the entire energy system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The following will further illustrate the above-mentioned characteristics, technical features, advantages and implementation methods of the present application in a clear and understandable manner through the description of preferred embodiments and in conjunction with the accompanying drawings. The following drawings are intended only to illustrate and explain the present application and do not limit the scope of the present application. Among them:

[0038] Figure 1 The present invention provides a flowchart of a method for diagnosing on-orbit faults of lithium-ion batteries in low-orbit satellites. DETAILED DESCRIPTION

[0039] In order to have a clearer understanding of the technical features, purposes and effects of this application, the specific implementation methods of this application are now described with reference to the accompanying drawings.

[0040] The on-orbit fault diagnosis method for lithium-ion batteries in low-orbit satellites provided in this application is suitable for quickly locating charging faults in lithium-ion batteries in the energy system of small satellites during on-orbit operation. By comprehensively and logically determining the satellite's orbital phase and the key characteristic parameters of the lithium-ion battery, the method diagnoses different charging faults that may occur in lithium-ion batteries on-orbit and affect the function of the energy system and the safety of the entire satellite. This method reserves sufficient time for subsequent emergency response or ground intervention, effectively improving the reliability and safety of the satellite's energy system.

[0041] like Figure 1 As shown, a method for on-orbit fault diagnosis of lithium-ion batteries in low-orbit satellites includes the following steps:

[0042] S1: Determine whether the satellite is in the illumination period. If the satellite is in the illumination period, proceed to step S2;

[0043] The satellite determines whether the illumination flag is equal to 1. If it is not equal to 1, the process ends directly, indicating that the satellite is in the Earth's shadow period and fault diagnosis cannot be performed. If it is equal to 1, it means that the satellite is in the illumination period, and the process goes to step S2.

[0044] S2: Determine whether the battery charging current is 0: If the charging current is equal to 0, proceed to step S3; if not, proceed to step S5;

[0045] S3: Determine whether the following conditions ① and ② are met at the same time: If both are met, proceed to step S4; if both are not met, it means that there is no fault in charging at this time, and the process ends directly.

[0046] Condition ①: The current battery capacity is less than the rated capacity of the battery;

[0047] Condition ②: The solar cell array current is greater than the load current.

[0048] S4: Determine whether the battery charging current setting level is equal to 0: If it is equal to 0, it is determined to be fault 3, and the fault is resolved by switching the power supply from the lower computer to the standby computer; if it is not equal to 0, it is determined to be fault 1, and the fault is resolved by sending a charging circuit connection command;

[0049] S5: Determine whether the current battery capacity is equal to the rated battery capacity: if they are equal, proceed to step S8; if not, proceed to step S6;

[0050] S6: Determine whether the following conditions ③, ④ and ⑤ are met simultaneously: If they are met at the same time, proceed to step S7; if they are not met at the same time, it means that there is no fault in charging at this time, and the process ends directly.

[0051] Condition 3: The current battery voltage is less than the constant current to constant voltage reference voltage value (the constant current to constant voltage reference voltage value is a pre-set value, and its setting method is common knowledge in the field. Those skilled in the art can set it in advance according to actual needs using methods in the prior art);

[0052] Condition ④: The difference between the solar cell array current and the load current is greater than the charging current;

[0053] Condition ⑤: The battery charging current is less than the current in the constant current charging section (the current in the constant current charging section is a pre-set value, and its setting method is common knowledge in the field. Those skilled in the art can set it in advance according to actual needs using methods in the prior art).

[0054] S7: Determine whether the charging current setting level is equal to the constant current section setting voltage value: If the two are not equal, it is determined to be fault 3, and the fault is resolved by switching the power supply from the lower computer to the standby computer; if the two are equal, it is determined to be fault 2, and the fault is resolved by sending a fast charging switch on command;

[0055] S8: Determine whether the battery charging current is greater than the charging termination current: If the charging current is greater than the charging termination current, proceed to step S9; if not, it means that there is no fault in charging at this time and the process ends directly.

[0056] S9: Determine whether the charging current setting level is equal to 0: If it is equal to 0, it is determined to be fault 4, and a command is sent to disconnect the fast charging switch and the BCR circuit to eliminate the fault; if it is not equal to 0, it is determined to be fault 3, and the fault is resolved by switching to the standby machine through the power supply lower machine.

[0057] Among them, fault 1 is an abnormal fault in the charging circuit, and the battery cannot be charged. This fault can be eliminated by sending a charging circuit connection command;

[0058] Fault 2 is an abnormal fault in the fast charging circuit. Charging cannot be terminated. You can disconnect the fast charging switch to eliminate the fault.

[0059] Fault 3 is an abnormal D / A output fault of the lower computer. You can send a power supply lower computer power-off command through the satellite service to eliminate this fault.

[0060] Fault 4: Charging cannot be terminated. This fault can be corrected by sending a command to disconnect the fast charging switch and BCR circuit.

[0061] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0062] The above description is only an illustrative embodiment of the present application and is not intended to limit the scope of the present application. Any equivalent changes, modifications and combinations made by any person skilled in the art without departing from the concept and principle of the present application shall fall within the scope of protection of the present application.

Claims

1. A method for diagnosing on-orbit faults of lithium-ion batteries in low-orbit satellites, comprising: S1: Determine whether the satellite is in the illumination period. If it is, proceed to step S2; S2: Determine whether the battery charging current is 0: If the charging current is equal to 0, proceed to step S3; if not, proceed to step S5; S3: Determine whether the following first and second conditions are met at the same time: If both conditions are met, proceed to step S4; if both conditions are not met, it means that there is no fault in charging at this time, and the process ends directly. The first condition: the current battery capacity is less than the rated battery capacity; The second condition: the solar cell array current is greater than the load current; S4: Determine whether the battery charging current setting level is equal to 0: if it is equal to 0, it is determined to be a third type of fault; if it is not equal to 0, it is determined to be a first type of fault; S5: Determine whether the current battery capacity is equal to the rated battery capacity: if they are equal, proceed to step S8; if they are not equal, proceed to step S6; S6: Determine whether the following third condition, fourth condition and fifth condition are met at the same time: If they are met at the same time, proceed to step S7; if they are not met at the same time, it means that there is no fault in charging at this time, and the process ends directly. The third condition: the current battery voltage is less than the constant current constant voltage reference voltage value; The fourth condition: the difference between the solar cell array current and the load current is greater than the charging current; Fifth condition: the battery charging current is less than the charging constant current stage current; S7: Determine whether the charging current setting level is equal to the constant current section setting voltage value: if not, it is determined to be a third type fault; If they are equal, it is judged as a second type of fault; S8: Determine whether the charging current of the battery is greater than the charge termination current: If the charging current is greater than the charge termination current, proceed to step S9; If the charging current is not greater than the charging termination current, it means that there is no fault in the charging and the process ends directly. S9: Determine whether the charging current setting level is equal to 0: If it is equal to 0, it is determined to be a fourth type of fault; if it is not equal to 0, it is determined to be a third type of fault.

2. The method according to claim 1, wherein The first type of fault is an abnormal fault in the charging circuit, and the battery cannot be charged.

3. The method according to claim 2, further comprising: When it is determined to be a first type fault, a charging circuit turn-on instruction is sent to resolve the fault.

4. The method according to claim 1, wherein The second type of fault is an abnormal fault in the fast charging circuit, and charging cannot be terminated.

5. The method according to claim 4, further comprising: When it is determined to be a second type of fault, a fast charging switch turning on instruction is sent to resolve the fault.

6. The method according to claim 1, wherein The third type of fault is the abnormal D / A output fault of the lower computer.

7. The method according to claim 6, further comprising: When it is determined to be a third type of fault, the satellite service sends a power supply lower-level machine a power cut-off instruction to resolve the fault.

8. The method according to claim 1, wherein The fourth type of fault is a charging failure.

9. The method according to claim 8, further comprising: When it is determined to be a fourth type of fault, a fast charging switch and BCR circuit disconnect instruction is sent to resolve the fault.

10. The method according to claim 1, wherein the constant current to constant voltage reference voltage value and the current in the constant current section of charging are preset values.

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