A method for autonomous distribution of electric energy for a spacecraft direct-drive electric propulsion power supply system

Abstract

This invention discloses an autonomous power distribution method for a spacecraft direct-drive electric propulsion power supply system, belonging to the field of spacecraft power technology. During the spacecraft power distribution process, this invention collects data on the power of the solar array, the power of the low-voltage load, and the current and voltage of the battery pack. It predicts the state of charge (SOC) of the battery pack and uses fuzzy rules for reasoning to adjust the operating level and power of the electric propulsion load based on a reference power. Simultaneously, it utilizes model predictive control to discretize the state space of the battery pack model, designing an objective function and constraints that enable high-precision tracking of the battery pack current, keeping the SOC within a safe range and extending its service life.

Description

Technical Field

[0001] This invention relates to a method for autonomous power distribution in a spacecraft direct-drive electric propulsion power supply system, belonging to the field of spacecraft power technology. Background Technology

[0002] Environmental conditions such as illumination, temperature, and incident angle vary greatly, and spacecraft missions are characterized by long on-orbit durations and strong autonomous planning capabilities. This necessitates that spacecraft power supply systems based on solar arrays and battery banks possess strong environmental adaptability, a wide operating range, and intelligent control functions. Therefore, balancing the high-power, adjustable-range requirements of electric propulsion with the operational safety and extended lifespan of battery banks represents an important research direction for energy management in spacecraft direct-drive electric propulsion systems.

[0003] When the output power of the solar array decreases, the power margin becomes insufficient to support high-power electric propulsion loads, necessitating the discharge of the battery bank to replenish energy. Once the solar array's output power recovers to a higher level, the battery bank is then recharged. However, frequent charging and discharging can easily lead to problems such as accelerated capacity decay, accelerated electrolyte consumption, increased internal resistance, elevated internal temperature, and reduced effective electrode area, ultimately shortening the battery bank's lifespan. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide an autonomous power distribution method for a spacecraft direct-drive electric propulsion power supply system. This method enables autonomous power distribution, which can both adjust the working level of the electric propulsion load and control the state of charge (SOC) of the battery pack within a safe range, thereby extending its service life.

[0005] The technical solution of this invention is: a method for autonomous power distribution in a spacecraft direct-drive electric propulsion power supply system, comprising:

[0006] Initialize the electric spacecraft propulsion load settings, which are divided into several levels from low to high according to the power consumption.

[0007] Collect data on the spacecraft's solar array power, battery pack current and voltage, and low-voltage load power;

[0008] The reference power allocated to the electric propulsion load is calculated based on the power of the solar cell array and the power of the low-voltage load, and the reference gear of the electric propulsion is determined based on the reference power.

[0009] Predict the SOC of the spacecraft's battery pack based on the battery pack current and voltage;

[0010] The adjustment power of the electric propulsion load is obtained by acquiring the power of the solar cell array and the SOC of the battery pack, and then superimposed with the reference gear of the electric propulsion to obtain the working power and corresponding working gear of the electric propulsion load.

[0011] Calculate the target current of the battery pack by using the power of the solar array, the power of the low-voltage load, and the operating power of the electric propulsion load, and achieve the tracking of the battery pack current.

[0012] Further, the maximum power of the electric propulsion load is P promax = P pv - P lowload ; where, P promax represents the maximum power that can be allocated to the electric propulsion load, P pv represents the power of the solar array, P lowload represents the power of the low-voltage load.

[0013] Further, the electric spacecraft propulsion load has N gears in ascending order of power consumption, and the corresponding powers are P pro [1], …, P pro [j], ……, P pro [N], 1 < j < N and j is an integer;

[0014] The determination of the reference gear of the electric propulsion includes:

[0015] When P pro [j - 1] < P promax ≤ P pro [j], the reference gear of the electric propulsion load is j, and the reference power P pro0 = P pro [j];

[0016] When P promax ≤ P pro [1], the reference gear of the electric propulsion load is 1, and the reference power P pro0 = P pro [1];

[0017] When P promax > P pro [N], the reference gear of the electric propulsion load is N, and the reference power P pro0 = P pro [N]; P promax is the maximum power of the electric propulsion load.

[0018] Further, the SOC of the battery pack is where, SOC0 can be set according to the open-circuit voltage U ocv of the battery pack, I bat represents the current of the battery pack, and Q0 represents the nominal capacity of the battery pack.

[0019] Further, the open-circuit voltage U ocv and current I batsatisfy Among them, U bat U represents the voltage of the battery pack. o R represents the polarization voltage of the battery pack. i R represents the ohmic internal resistance of the battery pack. o C represents the polarization resistance of the battery pack, and C represents the polarization capacitance of the battery pack.

[0020] Furthermore, the adjustment power of the electric propulsion load is obtained by fuzzy rules based on the power of the solar cell array and the state of charge (SOC) of the battery pack.

[0021] Furthermore, the target current of the battery pack is I * bat P represents the target current of the battery pack. pv P represents the power of the solar cell array. lowload P represents the low-voltage load power. pro U represents the maximum power of the electric propulsion load. bat This indicates the voltage of the battery pack.

[0022] Furthermore, the method for tracking the battery pack current is a model predictive control method.

[0023] A computer-readable storage medium storing a computer program, wherein when executed by a processor, the computer program implements the steps of the autonomous power distribution method for a spacecraft direct-drive electric propulsion power supply system.

[0024] An autonomous power distribution device for a spacecraft direct-drive electric propulsion power supply system includes a memory, a processor, and a computer program stored in the memory and executable on the processor. The device is characterized in that the processor executes the computer program to implement the steps of the autonomous power distribution method for the spacecraft direct-drive electric propulsion power supply system.

[0025] The advantages of this invention compared to the prior art are:

[0026] This invention collects data on the power of the solar array, the power of the low-voltage load, and the current and voltage of the battery pack during the spacecraft's power distribution process. It predicts the state of charge (SOC) of the battery pack and uses fuzzy rules for reasoning to adjust the operating level and power of the electric propulsion load based on a reference power. Simultaneously, it employs model predictive control to discretize the state space of the battery pack model, designing an objective function and constraints to achieve high-precision tracking of the battery pack current, thus controlling the SOC within a safe range and extending its service life. Attached Figure Description

[0027] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of illustrating the preferred embodiments and are not considered a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0028] Figure 1 This is the structural diagram of the direct-drive electric propulsion power supply system for spacecraft provided by the present invention.

[0029] Figure 2 This is the flowchart of the method for autonomous power distribution of the direct-drive electric propulsion power supply system for spacecraft provided by the present invention. Specific embodiments

[0030] In order to better understand the above technical solutions, the technical solutions of the present invention will be described in detail below through the drawings and specific embodiments. It should be understood that the specific features in the embodiments of the present invention and the embodiments are detailed descriptions of the technical solutions of the present invention, rather than limitations on the technical solutions of the present invention. Without conflict, the technical features in the embodiments of the present invention and the embodiments can be combined with each other.

[0031] The following further details the method for autonomous power distribution of a direct-drive electric propulsion power supply system for spacecraft provided by an embodiment of the present invention in conjunction with the drawings of the specification. The specific implementation methods may include: The method is used to formulate a power distribution strategy for the power supply system; the direct-drive electric propulsion power supply system for spacecraft includes a solar array, a battery pack, a battery charge and discharge module, a low-voltage load, and an electric propulsion load; the solar array provides power for the low-voltage load and the electric propulsion load; the battery pack provides power for the low-voltage load and the electric propulsion load through the battery charge and discharge module; when the power provided by the solar array is greater than the power of the low-voltage load and the electric propulsion load, the battery pack can also absorb the excess power through the battery charge and discharge module; the electric propulsion load is a discrete power load with multiple levels; the autonomous power distribution module implements the method for autonomous power distribution of the direct-drive electric propulsion power supply system for spacecraft.

[0032] The method includes:

[0033] Initialize and set the electric propulsion load, with a total of N levels from low to high in terms of power consumption, and the corresponding powers are P pro [1], …, P pro [j], ……, P pro [N], 1 < j < N and j is an integer.

[0034] Collect the power of the solar array, the current and voltage of the battery pack, and the power of the low-voltage load;

[0035] Based on the power of the solar cell array and the power of the low-voltage load, the reference power allocated to the electric propulsion load is calculated, and the reference gear of the electric propulsion is determined based on this power.

[0036] Based on the current and voltage of the battery pack, the SOC of the battery pack is predicted; the SOC of the battery pack is the state of charge.

[0037] The power of the solar array and the SOC of the battery pack are input into the fuzzy rule table to obtain the adjustment power of the electric propulsion load. The reference power of the electric propulsion is superimposed to obtain the working power and corresponding working level of the electric propulsion load.

[0038] By utilizing the power of the solar array, the power of the low-voltage load, and the power of the electric propulsion, the target current of the battery pack is calculated, and the MPC method is used to achieve high-precision tracking of the battery pack current; the MPC method is Model Predictive Control.

[0039] Optionally, the maximum power allocated to the electric propulsion load is:

[0040] P promax =P pv -P lowload

[0041] Where P promax P represents the maximum power that can be allocated to an electric propulsion load. pv P represents the power of the solar cell array. lowload This indicates the power of the low-voltage load.

[0042] When the judgment condition is met, P pro [j-1] <P promax ≤P pro At [j], the reference gear of the electric propulsion load is j, and the reference power P of the electric propulsion load is... pro0 =P pro [j]; When the judgment condition is met, P promax ≤P pro [1] When the reference gear of the electric propulsion load is 1, the reference power P of the electric propulsion load is 1. pro0 =P pro [1]; when the judgment condition P is met promax >P pro When [N], the reference gear for the electric propulsion load is N, and the reference power P for the electric propulsion load is... pro0 =P pro [N].

[0043] Optionally, the formula for predicting the SOC of a battery pack is:

[0044]

[0045] SOC0 can be determined based on the open-circuit voltage U of the battery pack. ocv The OCV-SOC curve shows that I bat Q0 represents the current of the battery pack, and Q0 represents the nominal capacity of the battery pack.

[0046] Open circuit voltage U of the battery pack ocv and current I bat The relationship between them is:

[0047]

[0048] Among them U bat U indicates that based on the voltage of the battery pack, o R represents the value based on the polarization voltage of the battery pack. i R represents the ohmic internal resistance of the battery pack. o C represents the polarization resistance of the battery pack, and C represents the polarization capacitance of the battery pack.

[0049] Optionally, the regulating power ΔP of the electric propulsion load pro It can be obtained from the power of the solar array and the state of charge (SOC) of the battery pack using fuzzy rules, wherein the fuzzy rules are as follows:

[0050]

[0051] Regulation power ΔP of electric propulsion load pro Superimposed reference power P pro0 The operating power P of the electric propulsion load is obtained. pro and the corresponding work level j pro .

[0052] Optionally, the target current of the battery pack is:

[0053]

[0054] Among them I * bat This indicates the target current of the battery pack.

[0055] Optionally, the process of achieving high-precision tracking of battery pack current using the MPC method includes:

[0056] The battery pack model is discretized, and the state space expression at time k is:

[0057]

[0058] in A a B a Ca It is the coefficient matrix of the model. C a =

[11] , T ss The sampling interval is denoted as .

[0059] Set the prediction time domain to N. p and control time domain is N c The expression for the actual current Y(k) of the battery pack is:

[0060]

[0061] In the formula, C b =[0 11]

[0062] Design the objective function and constraints. The objective function J(k) aims to track the battery current of the battery pack with high precision, and its form is:

[0063]

[0064] Where Q represents the tracking weight, R represents the control weight, and Y... ref Indicates the target current value I of the battery pack * bat ε represents the relaxation factor, ρ represents the relaxation factor weighting coefficient, and the state parameters and control variables are subject to the following constraints:

[0065]

[0066] Among them, U o,min and U o,max These represent the minimum and maximum values ​​of the polarization voltage, respectively; ΔSOC min and ΔSOC max These represent the minimum and maximum values ​​of the SOC increment, respectively; I bat,min and I bat,max These represent the minimum and maximum values ​​of the battery pack current, respectively; U k o ΔSOC k and I k bat These represent the values ​​of polarization voltage, SOC increment, and battery pack current at time k, respectively.

[0067] In the solution provided in the embodiments of the present invention, a method and device for autonomous power distribution of a spacecraft direct-drive electric propulsion power supply system is intended to achieve autonomous power distribution of the spacecraft, which can both adjust the working level of the electric propulsion load and control the SOC of the battery pack within a safe range, thereby extending its service life.

[0068] Example 1

[0069] The method for autonomous power distribution of the direct-drive electric propulsion power supply system of a spacecraft in this embodiment is used to formulate a power distribution strategy for the power supply system of the spacecraft. As Figure 1 shown, the direct-drive electric propulsion power supply system of the spacecraft includes a solar array, a battery bank, a battery charge and discharge module, a low-voltage load, and an electric propulsion load; the solar array provides power for the low-voltage load and the electric propulsion load; the battery bank provides power for the low-voltage load and the electric propulsion load through the battery charge and discharge module; when the power provided by the solar array is greater than the power of the low-voltage load and the electric propulsion load, the battery bank can also absorb the excess power through the battery charge and discharge module; the electric propulsion load is a power discrete load with multiple gears; the autonomous power distribution module implements the method for autonomous power distribution of the direct-drive electric propulsion power supply system of the spacecraft.

[0070] As Figure 2 shown, the method for autonomous power distribution of the direct-drive electric propulsion power supply system of the spacecraft in the embodiment of the present invention includes the following steps.

[0071] Step 1: Initialize and set the electric propulsion load, with a total of N gears from low to high in terms of power consumption, and the corresponding powers are P pro [1], …, P pro [j], ……, P pro [N], where 1 < j < N and j is an integer.

[0072] Step 2: Collect the power of the solar array, the current and voltage of the battery bank, and the power of the low-voltage load; calculate the reference power allocated to the electric propulsion load based on the power of the solar array and the low-voltage load, and determine the reference gear of the electric propulsion according to this power. The maximum power allocated to the electric propulsion load is:

[0073] P promax = P pv - P lowload

[0074] where P promax represents the maximum power that can be allocated to the electric propulsion load, P pv represents the power of the solar array, and P lowload represents the power of the low-voltage load. When the judgment condition is met, when P pro [j - 1] < P promax ≤ P pro [j], the reference gear of the electric propulsion load is j, and the reference power P pro0 = P pro [j]; when the judgment condition is met, when P promax ≤ P pro [1], the reference gear of the electric propulsion load is 1, and the reference power P pro0=P pro [1]; when the judgment condition P is met promax >P pro When [N], the reference gear for the electric propulsion load is N, and the reference power P for the electric propulsion load is... pro0 =P pro [N].

[0075] Step 3: Predict the SOC of the battery pack based on its current and voltage; the SOC of the battery pack is its state of charge. The formula for predicting the SOC of the battery pack is:

[0076]

[0077] SOC0 can be determined based on the open-circuit voltage U of the battery pack. ocv The OCV-SOC curve shows that I bat Q0 represents the current of the battery pack, and Q0 represents the nominal capacity of the battery pack.

[0078] Open circuit voltage U of the battery pack ocv and current I bat The relationship between them is:

[0079]

[0080] Among them U bat U indicates that based on the voltage of the battery pack, o R represents the value based on the polarization voltage of the battery pack. i R represents the ohmic internal resistance of the battery pack. o C represents the polarization resistance of the battery pack, and C represents the polarization capacitance of the battery pack.

[0081] Step 4: Increase the power P of the solar cell array pv The battery pack's state of charge (SOC) is input into a fuzzy rule table to obtain the regulating power ΔP of the electric propulsion load. pro The fuzzy rule table is

[0082]

[0083] Regulation power ΔP of electric propulsion load pro Superimposed reference power P pro0 The operating power P of the electric propulsion load is obtained. pro and the corresponding work level j pro .

[0084] Step 5: Calculate the target current of the battery pack using the power of the solar array, the power of the low-voltage load, and the operating power of the electric propulsion system. Then, use the MPC method to achieve high-precision tracking of the battery pack current. The MPC method is Model Predictive Control.

[0085] Target current I of the battery pack * bat for:

[0086]

[0087] The process of achieving high-precision current tracking in battery packs using the MPC method includes:

[0088] The battery pack model is discretized, and the state space expression at time k is:

[0089]

[0090] in A a B a C a It is the coefficient matrix of the model. C a =[1 1], T ss The sampling interval is denoted as .

[0091] Set the prediction time domain to N. p and control time domain is N c The expression for the actual current Y(k) of the battery pack is:

[0092]

[0093] In the formula,

[0094] C b =[0 1 1]

[0095] Design the objective function and constraints. The objective function J(k) aims to track the battery current of the battery pack with high precision, and its form is:

[0096]

[0097] Where Q represents the tracking weight, R represents the control weight, and Y... ref Indicates the target current value I of the battery pack * bat ε represents the relaxation factor, ρ represents the relaxation factor weighting coefficient, and the state parameters and control variables are subject to the following constraints:

[0098]

[0099] Among them, U o,min and U o,max These represent the minimum and maximum values ​​of the polarization voltage, respectively; ΔSOC min and ΔSOC max These represent the minimum and maximum values ​​of the SOC increment, respectively; I bat,min and I bat,max These represent the minimum and maximum values ​​of the battery pack current, respectively; U k o ΔSOC k and I k bat These represent the values ​​of polarization voltage, SOC increment, and battery pack current at time k, respectively.

[0100] This invention provides a computer-readable storage medium storing computer instructions that, when executed on a computer, cause the computer to perform... Figure 2 The method described.

[0101] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0102] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0103] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0104] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0105] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0106] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for autonomous power distribution in a spacecraft direct-drive electric propulsion power supply system, characterized in that, include: Initialize the electric spacecraft propulsion load settings, which are divided into several levels from low to high according to the power consumption. Collect data on the spacecraft's solar array power, battery pack current and voltage, and low-voltage load power; The reference power allocated to the electric propulsion load is calculated based on the power of the solar cell array and the power of the low-voltage load, and the reference gear of the electric propulsion is determined based on the reference power. Predict the SOC of the spacecraft's battery pack based on the battery pack current and voltage; The adjustment power of the electric propulsion load is obtained by acquiring the power of the solar cell array and the SOC of the battery pack, and then superimposed with the reference gear of the electric propulsion to obtain the working power and corresponding working gear of the electric propulsion load. By utilizing the power of the solar cell array, the power of the low-voltage load, and the operating power of the electric propulsion load, the target current of the battery pack is calculated, and the tracking of the battery pack current is achieved.

2. The method for autonomous power distribution in a spacecraft direct-drive electric propulsion power supply system according to claim 1, characterized in that, The maximum power of the electric propulsion load is P. promax =P pv -P lowload ; Among them, P promax P represents the maximum power that can be allocated to an electric propulsion load. pv P represents the power of the solar cell array. lowload This indicates the power of the low-voltage load.

3. The method for autonomous power distribution in a spacecraft direct-drive electric propulsion power supply system according to claim 2, characterized in that, The electric spacecraft propulsion load has a total of N gears according to the power consumption from low to high, and the corresponding power is P pro [1], …, P pro [j], ……, P pro [N], where 1 < j < N and j is an integer; The reference gear for determining electric propulsion includes: When P pro [j-1] <P promax ≤P pro At [j], the reference gear of the electric propulsion load is j, and the reference power P of the electric propulsion load is... pro0 =P pro [j]; When P promax ≤P pro [1] When the reference gear of the electric propulsion load is 1, the reference power P of the electric propulsion load is 1. pro0 =P pro [1]; When P promax >P pro When [N], the reference gear for the electric propulsion load is N, and the reference power P for the electric propulsion load is... pro0 =P pro [N];P promax This represents the maximum power of the electric propulsion load.

4. The method for autonomous power distribution in a spacecraft direct-drive electric propulsion power supply system according to claim 1, characterized in that, The battery pack's SOC is Among them, SOC0 can be determined based on the open-circuit voltage U of the battery pack. ocv Settings, I bat Q0 represents the current of the battery pack, and Q0 represents the nominal capacity of the battery pack.

5. The method for autonomous power distribution in a spacecraft direct-drive electric propulsion power supply system according to claim 4, characterized in that, The open-circuit voltage U of the battery pack ocv and current I bat satisfy Among them, U bat U represents the voltage of the battery pack. o R represents the polarization voltage of the battery pack. i R represents the ohmic internal resistance of the battery pack. o C represents the polarization resistance of the battery pack, and C represents the polarization capacitance of the battery pack.

6. The method for autonomous power distribution in a spacecraft direct-drive electric propulsion power supply system according to claim 1, characterized in that, The adjustment power of the electric propulsion load is obtained by fuzzy rules based on the power of the solar array and the state of charge (SOC) of the battery pack.

7. The method for autonomous power distribution in a spacecraft direct-drive electric propulsion power supply system according to claim 1, characterized in that, The target current of the battery pack is I * bat P represents the target current of the battery pack. pv P represents the power of the solar cell array. lowload P represents the low-voltage load power. pro U represents the maximum power of the electric propulsion load. bat This indicates the voltage of the battery pack.

8. The method for autonomous power distribution in a spacecraft direct-drive electric propulsion power supply system according to claim 1, characterized in that, The method for tracking the battery pack current is a model predictive control method.

9. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1 to 8.

10. An autonomous power distribution device for a spacecraft direct-drive electric propulsion power supply system, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1 to 8.

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