On-orbit fault diagnosis method for lithium ion storage battery of low-orbit satellite

Abstract

The invention provides an on-orbit fault diagnosis method for a lithium ion storage battery of a low-orbit satellite. The method is suitable for rapid positioning when a charging fault occurs to the lithium ion storage battery in an energy system when a small satellite operates on orbit. Through comprehensive logic judgment of key characteristic parameters such as a charging current, a current electric quantity, a current voltage, a charging current set level and the like of a lithium ion storage battery at an orbit stage of a satellite in orbit, different charging faults which possibly occur on orbit of the lithium ion storage battery and influence energy system functions and whole satellite safety are diagnosed; enough time is reserved for subsequent satellite emergency processing or ground intervention processing, and the reliability and safety of a satellite energy system can be remarkably improved.

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 of low-orbit satellites, which is suitable for rapid positioning of charging faults of lithium-ion batteries in energy systems of small satellites when they are in orbit. Background Art

[0002] As a key system of the satellite, the satellite energy system plays an important role in generating, regulating, storing and distributing electric energy for the entire satellite. It provides a source of energy for the satellite platform and onboard payloads throughout their life cycle, and is the bottom line for the safety of satellites in orbit. The satellite energy system mainly consists of three parts: solar arrays, battery packs and power controllers. During the Earth's shadow period, the entire satellite is powered by the discharge of the battery pack. During the illumination period, in addition to giving priority to the power supply of the onboard loads, the remaining energy of the solar array is used to charge the battery pack. Compared with other types of space batteries, lithium-ion batteries have the advantages of high energy density, long cycle life and low self-discharge current. They have been widely used as the main energy storage power source in medium and low orbit spacecraft.

[0003] Although lithium-ion batteries have many advantages, their disadvantages are also very obvious. Excessive decomposition of battery electrolytes will cause the internal temperature and pressure of lithium-ion batteries to increase, which will lead to safety problems on orbit. Therefore, lithium-ion batteries are strictly prohibited from being overcharged. On the other hand, undercharging of lithium-ion batteries will also cause an imbalance in the energy of the entire satellite on orbit, affecting the failure of the satellite's on-orbit mission. The application of lithium-ion batteries on low-orbit small satellites is more independent of other orbital satellites. For example, the orbital period of low-orbit satellites is relatively short, corresponding to more cycles of lithium battery charge and discharge cycles. As the on-orbit working time increases, the probability of charging failure increases due to the high sensitivity of lithium-ion batteries to overcharging and multiple on-orbit charge and discharge cycles in low orbit.

[0004] In the past, the diagnostic strategy for abnormal on-orbit charging of lithium-ion batteries in low-orbit small satellites was still limited to extracting direct characteristic parameters (such as charging current), and did not make full use of satellite on-orbit related information or some potential symptom data for comprehensive analysis. Therefore, the existing charging fault diagnosis strategy mainly has the following problems:

[0005] (1) The accuracy and reliability of in-depth 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, since the actual on-orbit battery voltage changes relatively slowly, fault diagnosis and processing 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 comprehensively, and ignored the relationship between other equipment in the system and the battery charging abnormality. 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 single feature parameter extraction, which leads to insufficient accuracy and real-time performance of on-orbit abnormal charging diagnosis of lithium-ion batteries, an on-orbit fault diagnosis method for low-orbit satellite lithium-ion batteries is proposed, which can quickly diagnose on-orbit faults of low-orbit satellite lithium-ion batteries.

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

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

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

[0012] S3: Determine whether the following first condition and second condition 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.

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

[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 power of the battery is equal to the rated power of the battery: 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 voltage of the battery is less than the constant current to constant voltage reference voltage value;

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

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

[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 charging current of the battery is greater than the charging termination current: If the charging current is greater than the charging 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 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 turn-on 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, it also includes: when it is determined to be a third type of fault, the satellite service sends a power supply lower 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 to terminate 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 a 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 charging constant current section current 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 a relatively single key characteristic parameter for fault diagnosis. The judgment criteria and logic strategy 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 array current in battery pack charging fault diagnosis, and uses the solar 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 explain the above characteristics, technical features, advantages and implementation methods of the present application in a clear and understandable manner through the description of the preferred embodiments and in combination with the accompanying drawings. The following drawings are only intended 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 is a flowchart of an on-orbit fault diagnosis method for lithium-ion batteries of low-orbit satellites according to the present application. DETAILED DESCRIPTION

[0039] In order to have a clearer understanding of the technical features, purposes and effects of the present application, the specific implementation methods of the present 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 the rapid positioning of charging faults in lithium-ion batteries in the energy system of small satellites when they are in orbit. Through comprehensive logical judgment of the orbital stage of the satellite and the key characteristic parameters of the lithium-ion battery, different charging faults that may occur in the lithium-ion battery in orbit and affect the function of the energy system and the safety of the entire satellite are diagnosed, and sufficient time is reserved for subsequent emergency treatment of the satellite or ground intervention and disposal, effectively improving the reliability and safety of the satellite energy system.

[0041] like Figure 1 As shown, a method for on-orbit fault diagnosis of lithium-ion batteries in low-orbit satellites comprises 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 charging current of the battery is 0: if the charging current is equal to 0, proceed to step S3; if not equal to 0, 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 battery capacity;

[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 as fault 3, and the fault is resolved by switching the power supply lower machine to the standby machine; if it is not equal to 0, it is determined as fault 1, and the fault is resolved by sending a charging circuit connection command;

[0049] S5: Determine whether the current power of the battery is equal to the rated power of the battery: if the two 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 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.

[0051] Condition ③: The current voltage of the battery 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, and 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 charging constant current section current (the charging constant current section current 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 as fault 3, and the fault is resolved by switching the power supply lower machine to the standby machine; if the two are equal, it is determined as 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 judged as 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 judged as fault 3, and the fault is eliminated 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 cut-off command through the satellite service to eliminate this fault;

[0060] Fault 4 is a charging failure that cannot be terminated. This fault can be eliminated by sending a fast charging switch and BCR circuit disconnect command.

[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 may 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 technician in the field 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 so, proceed to step S2; S2: Determine whether the charging current of the battery is 0: if the charging current is equal to 0, proceed to step S3; if not equal to 0, proceed to step S5; S3: Determine whether the following first condition and second condition 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 power is less than the rated battery power; The second condition: the solar cell array current is greater than the load current; S4: Determine whether the charging current setting level of the battery 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 power of the battery is equal to the rated power of the battery: 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 voltage of the battery is less than the constant current to constant voltage reference voltage value; 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 they are not equal, 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 charging termination current: if the charging current is greater than the charging 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 process 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 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 an 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 to terminate.

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 disconnection 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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