Deep space probe power system based on solar cell array power prediction

Abstract

The application provides a deep space power supply system based on solar cell array power prediction, and is particularly suitable for deep space probes using electric propulsion. The deep space power supply system based on solar cell array power prediction comprises a solar cell array, a solar cell calibration piece, a solar cell calibration circuit, an electric propulsion gear adjuster, a series type power regulator and a central processing unit. The solar cell calibration circuit collects the I-V curve of the solar cell calibration piece, compares and processes the I-V curve of the solar cell array collected by the central processing unit, so as to obtain the correction coefficient and the irradiation coefficient of the solar cell array curve. The correction coefficient and the irradiation coefficient are used to correct and process the ground test solar cell piece curve, so as to meet the high-precision solar cell array power prediction requirement. The electric propulsion gear adjuster selects the appropriate electric propulsion thruster gear according to the accurate solar cell array predicted power, so as to meet the requirement of maximizing the use of the on-orbit output power of the solar cell array.

Description

Technical Field

[0001] This invention proposes a deep space probe power system based on the predicted power of a solar cell array, belonging to the field of spacecraft power technology. It is particularly suitable for deep space probes where illumination conditions cannot be accurately predicted and which use electric propulsion or have large variations in electrical load. Background Technology

[0002] For deep space exploration spacecraft, the IV curve of their solar array varies greatly throughout the mission cycle. Without increasing the solar array area, the parallel regulators commonly used in Earth-orbiting spacecraft cannot simultaneously meet the power supply requirements at perihelion and aphelion. To adapt to the wide range of IV curve variations, a series regulator topology is required to meet power regulation needs. Simultaneously, to ensure stable system output, the operating point of the solar array needs to be kept to the right of the maximum power point, which differs significantly from the traditional parallel regulator where the operating point is to the left of the maximum power point.

[0003] Lighting conditions in deep space are unpredictable, and temperature and incident angle conditions vary greatly. Although series-type regulators can adjust the output power of the solar array according to the load, the right side of the maximum power point on the curve is more affected by light intensity and temperature measurement errors than the left side, making it difficult to determine the output capacity of the solar array. However, for deep space probes using electric propulsion, the power demand during on-orbit electric propulsion activation is high, leaving very limited overall power margin. Especially towards the end of their lifespan, the output power of the solar array decreases due to light intensity, making it difficult to support high-power electric propulsion loads. Therefore, it is necessary to maximize the utilization of the solar array power to support higher-power electric propulsion activation. Thus, accurately predicting the solar array power and selecting the appropriate thruster setting is a problem that needs to be solved. Summary of the Invention

[0004] The technical problem solved by this invention is:

[0005] This invention provides a deep-space power system based on solar array power prediction, comprising a solar array, solar cell calibration plates, a solar cell calibration circuit, an electric propulsion shift regulator, a series-type power regulator, and a central processing unit. The solar cell calibration circuit acquires the IV curves of the solar cell calibration plates and compares and processes them with the IV curves of the solar array acquired by the central processing unit to obtain correction factors and irradiance coefficients for the solar array curves. These correction factors and irradiance coefficients are used to correct and process the curves of the ground-based tested solar cells to achieve high-precision solar array power prediction. The electric propulsion shift regulator selects the appropriate electric propulsion thrust level based on the accurate predicted solar array power to maximize the on-orbit output power of the solar array.

[0006] The technical solution of this invention is:

[0007] A deep-space power system based on solar array power prediction includes a solar array, solar cell calibration plates, a solar cell calibration circuit, an electric propulsion level regulator, a series-type power regulator, and a central processing unit (CPU). The system is characterized by: the solar array outputting two busbars via two sets of isolation diodes; the negative terminal of one set of isolation diodes is connected to the input terminal of the electric propulsion level regulator, and the output terminal of the electric propulsion level regulator is connected to the thruster input terminal, thus forming the electric propulsion busbar; the negative terminal of the other set of isolation diodes is connected to the input terminal of the series-type power regulator, and the output terminal of the series-type power regulator is connected to the platform load, thus forming the platform busbar. The CPU includes a solar array curve correction module, a solar array power prediction module, and an electric propulsion level selection module. The solar array curve correction module obtains voltage and current correction coefficients and irradiance coefficients through calculations on several sets of IV curves; the solar array power prediction module calculates the predicted power of the solar array based on ground-based test curves using the voltage and current correction coefficients and irradiance coefficients; and the electric propulsion level selection module selects the operating level of the electric propulsion system according to the predicted power of the solar array.

[0008] In the early stages of its lifespan, the high light intensity and large output power of the detector's solar array are sufficient to power the electric propulsion thrusters at their maximum setting and ensure stable operation of the entire power system. At this time, all power switches K1 to Kn at the front end of the grid acceleration power supply in the electric propulsion level regulator are in the ON state. Because the overall power is sufficient in the early stages of life, and the electric propulsion system operates at its maximum setting without involving changes in the propulsion level, and because the solar array's operating point is always to the right of the maximum power point, the system is very stable. Therefore, this stage is the most suitable for correcting the solar array curves and predicting the output power of the solar array when its power is insufficient in the later stages.

[0009] Correcting the solar array curves requires at least three sets of curves: one set of IV curves (a) acquired by the solar cell calibration circuit from the solar cell calibration wafers; one set of IV curves (b) from the output of the solar array acquired by the central processing unit (CPU); and one set of IV curves (c) from ground-based test solar cells. The ground-based test solar cell IV curves (c) were obtained under conditions of 25°C and 0° solar incidence. To facilitate the establishment of the correction model, the IV curves of the solar cells and the solar array acquired in orbit need to be normalized for temperature and solar incidence. Normalization first requires obtaining the temperature telemetry data and the solar incidence angle at the current attitude of the in-orbit solar cells and the solar array. Then, through conversion of temperature and incidence coefficients, the data is normalized to the in-orbit data under conditions of 25°C and 0° solar incidence. In this paper, the IV curves (a) from the solar cell calibration wafers and the output IV curves (b) from the solar array are the normalized data. All three sets of IV curves are input into the solar array curve correction module of the CPU for calculation.

[0010] The calculation and processing of the solar cell array curve correction module of the central processing unit first multiplies the voltages Va1 to Van of the solar cell calibration plate under different light intensities collected by the solar cell calibration circuit by the total number of solar cells connected in series Ns. Then, it divides the actual output voltages Vb1 to Vbn of the solar cell array collected by the central processing unit by the product of Va1 to Van and Ns, and takes the average to obtain the voltage correction coefficient Kv. Then, it multiplies the currents Ia1 to Ian of the solar cell calibration plate under different light intensities collected by the solar cell calibration circuit by the total number of solar cells connected in parallel Np. Then, it divides the actual output currents Ib1 to Ibn of the solar cell array collected by the central processing unit by the product of Ia1 to Ian and Np, and takes the average to obtain the current correction coefficient Ki. Next, the voltage Va1 of the solar cell calibration plate, collected by the solar cell calibration circuit, is divided by the voltage Vc1 of the ground-based test solar cell under the corresponding light intensity to obtain the voltage irradiance coefficient Fv; the current Ia1 of the solar cell calibration plate, collected by the solar cell calibration circuit, is divided by the current Ic1 of the ground-based test solar cell under the corresponding light intensity to obtain the current irradiance coefficient Fi. The solar array curve correction module inputs the voltage correction coefficient Kv, current correction coefficient Ki, voltage irradiance coefficient Fv, and current irradiance coefficient Fi obtained from the above calculations into the solar array power prediction module to predict the output power of the solar array.

[0011] To predict the output power of the solar array at the next operating point of the electric propulsion system, the solar array power prediction module multiplies the ground-tested solar cell voltage Vcm under the corresponding light intensity at that operating point by the voltage correction factor Kv and the voltage irradiance factor Fv, and then multiplies it by the total number of solar cells connected in series Ns to obtain the predicted solar array voltage Vm. The ground-tested solar cell current Icm under the corresponding light intensity at that operating point is multiplied by the current correction factor Ki and the current irradiance factor Fi, and then multiplies it by the total number of solar cells connected in parallel Np to obtain the predicted solar array current Im. The product of the predicted solar array voltage Vm and the predicted solar array current Im is the predicted solar array power Pm. The solar array power prediction module then inputs the calculated predicted solar array power Pm into the electric propulsion gear selection module for processing.

[0012] In the electric propulsion gear selection module, the estimated solar array power Pm obtained from the solar array power prediction module is subtracted from the current platform load power Pf and the reserved power margin P0 to obtain the available electric propulsion power Pd. The available electric propulsion power Pd is then divided by the power Pa of a single grid acceleration power source and rounded to obtain the number of available grid acceleration power sources X. Based on the number of available grid acceleration power sources X calculated by the electric propulsion gear selection module, the electric propulsion gear regulator on the electric propulsion bus is controlled. By activating the power switches at the front ends of the corresponding number of grid acceleration power sources, the thruster obtains the maximum available electric propulsion power under this operating condition.

[0013] Compared with the prior art, the beneficial effects of the present invention are:

[0014] 1. Adding a solar array power prediction stage to the power system of a deep space probe can effectively address the stringent mission requirements such as the inability to accurately predict illumination conditions and the large range of temperature and solar incidence angle variations. It is also particularly suitable for applications using electric propulsion or with large variations in electrical load.

[0015] 2. Add a solar cell array curve correction module to the central processing unit, and add a solar cell calibration plate and calibration circuit outside the solar cell array. By comparing the output voltage and current of the solar cell calibration plate with those of the solar cell array, the correction coefficients of voltage and current and the irradiance coefficient can be calculated. Based on the ground test curve, the prediction accuracy of the solar cell array power under different light intensities can be improved.

[0016] Third, a set of IV curves of solar cells under different light intensities obtained from ground tests are pre-stored in the central processing unit. By comparing them with the IV curves of solar cell calibration cells obtained from on-orbit tests, the irradiance factor of the solar cell can be obtained, thereby improving the scientific data related to solar cells.

[0017] Fourth, by first predicting the power of the solar array and then adjusting the electric propulsion gear accordingly, the problem of mismatch between the output power of the solar array and the power of the electric propulsion load can be effectively avoided, ensuring the safe operation of the thruster across the entire mission range, thereby effectively improving the stability and reliability of the power system. Attached Figure Description

[0018] Figure 1 This is a topology diagram of a deep-space power system based on the predicted power of a solar cell array, as presented in this invention.

[0019] Figure 2 This is a schematic diagram of the logical structure of the central processing unit of the present invention;

[0020] Figure 3 This is a flowchart of the central processing unit's operation in this invention. Detailed Implementation

[0021] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.

[0022] Example

[0023] like Figure 1 As shown, the deep space power system based on solar cell array power prediction of the present invention includes a solar cell array, isolation diodes, solar cell calibration plates, solar cell calibration circuit, electric propulsion gear adjuster, thruster, series power regulator, battery pack, platform load and central processing unit.

[0024] Figure 1 In the example, the solar array supplies power to the thruster load via isolation diode D1 and then to the electric propulsion gear regulator, thus forming the electric propulsion bus power supply line. Additionally, the solar array supplies power to the platform load via isolation diode D2 and then to a series-type power regulator, forming the platform bus power supply line. To ensure the safe and reliable power supply to the platform load, a battery bank is also connected to the platform bus. This example uses only one solar array and two isolation diodes; in practical applications, multiple parallel connections can be used depending on power requirements. The electric propulsion gear regulator includes power switches and grid acceleration power supplies. Each grid acceleration power supply has a separate power switch at its input, forming a branch. Multiple power switches connected in series to form grid acceleration power supply branches are connected in parallel to form a group.

[0025] The central processing unit contains three modules: a solar array curve correction module, a solar array power prediction module, and an electric propulsion gear selection module.

[0026] In the early stages of its lifespan, the light intensity is high, and the output power of the detector's solar array is sufficient to power the electric propulsion thruster at its maximum setting and ensure stable operation of the entire power system. Figure 1 In the example, all power switches K1 to Kn at the front end of the grid acceleration power supply are in the ON state, and grid acceleration power supplies _1 to _3 are all operating. At this time, the electric propulsion system operates at maximum power, and the thrusters also provide maximum thrust. At this point, the solar array curve is corrected, and the output power of the solar array is predicted when the array power is insufficient in the later stages.

[0027] Correcting the solar cell array curves requires at least three sets of curves: a set of IV curves a obtained by the solar cell calibration circuit from the solar cell calibration cells, b set of solar cell array output IV curves b obtained by the central processing unit, and c set of ground-based test solar cell IV curves pre-injected from the ground.

[0028] The IV curve c of the ground-based solar cell was obtained under conditions of 25°C and 0° solar incidence. To facilitate the establishment of a correction model, the IV curves of the solar cells and the solar array acquired in orbit need to be normalized for temperature and solar incidence. The normalization process first requires obtaining the temperature telemetry data of the solar cells and the solar array in orbit and the solar incidence angle at the current attitude. Then, the data is converted by processing temperature coefficients and incidence angle coefficients, and finally normalized to the in-orbit data under the conditions of 25°C and 0° solar incidence.

[0029] In this paper, the IV curve a of the solar cell calibration sheet and the IV curve b of the solar cell array output are normalized data.

[0030] All three sets of IV curves are input into the solar cell array curve correction module of the central processing unit for calculation.

[0031] This example uses three sets of curves. In practical applications, more sets of solar cell array IV curves can be collected according to mission requirements. However, all curves collected in orbit need to be normalized for temperature and solar incidence angle.

[0032] A schematic diagram of the logical structure of a central processing unit is shown below. Figure 2As shown, the solar cell array curve correction module first multiplies the voltages Va1 to Van of the solar cell calibration cells under different light intensities collected by the solar cell calibration circuit by the total number of solar cells connected in series Ns. Then, it divides the actual output voltages Vb1 to Vbn of the solar cell array collected by the central processing unit by the product of Va1 to Van and Ns, and takes the average to obtain the voltage correction coefficient Kv. The module then multiplies the currents Ia1 to Ian of the solar cell calibration cells under different light intensities collected by the solar cell calibration circuit by the total number of solar cells connected in parallel Np. Then, it divides the actual output currents Ib1 to Ibn of the solar cell array collected by the central processing unit by the product of Ia1 to Ian and Np, and takes the average to obtain the current correction coefficient Ki. Then, the voltage Va1 of the solar cell calibration plate acquired by the solar cell calibration circuit is divided by the voltage Vc1 of the ground-based test solar cell under the corresponding light intensity to obtain the voltage irradiance coefficient Fv; the current Ia1 of the solar cell calibration plate acquired by the solar cell calibration circuit is divided by the current Ic1 of the ground-based test solar cell under the corresponding light intensity to obtain the current irradiance coefficient Fi. The solar array curve correction module inputs the voltage correction coefficient Kv, current correction coefficient Ki, voltage irradiance coefficient Fv, and current irradiance coefficient Fi obtained from the above calculations into the solar array power prediction module to predict the output power of the solar array.

[0033] To predict the output power of the solar array at the next operating point of the electric propulsion system, the solar array power prediction module multiplies the ground-tested solar cell voltage Vcm under the corresponding light intensity at that operating point by the voltage correction factor Kv and the voltage irradiance factor Fv, and then multiplies it by the total number of solar cells connected in series Ns to obtain the predicted solar array voltage Vm. The ground-tested solar cell current Icm under the corresponding light intensity at that operating point is multiplied by the current correction factor Ki and the current irradiance factor Fi, and then multiplies it by the total number of solar cells connected in parallel Np to obtain the predicted solar array current Im. The product of the predicted solar array voltage Vm and the predicted solar array current Im is the predicted solar array power Pm. The solar array power prediction module then inputs the calculated predicted solar array power Pm into the electric propulsion gear selection module for processing.

[0034] In the electric propulsion gear selection module, the estimated power Pm of the solar cell array obtained from the solar cell array power prediction module is subtracted from the current platform load power Pf and the reserved power margin P0 (i.e., power margin, such as the actual output is less than the theoretical output in order to ensure the overall equipment operation is stable, and the reserved power margin is the difference between the two) to obtain the available electric propulsion power Pd. The available electric propulsion power Pd is then divided by the power Pa of a single grid acceleration power supply and rounded to obtain the number of available grid acceleration power supplies X.

[0035] Based on the number X of available grid acceleration power supplies calculated by the electric propulsion gear selection module, the electric propulsion gear regulator on the electric propulsion bus is controlled to keep only power switches K1 to Kx on, while power switches Kx+1 to Kn are off. At this time, the corresponding grid acceleration power supplies _1 to _x output normal power, while grid acceleration power supplies _x+1 to _n cease operation. In this state, the thruster operates at its maximum available power while maintaining system safety and stability.

[0036] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances. In the description of this specification, references to terms such as "an embodiment," "example," and "specific example" indicate that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0037] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.

Claims

1. A power system for a deep space probe based on the predicted power of a solar cell array, characterized in that: This includes solar cell arrays, isolation diodes, solar cell calibration plates, solar cell calibration circuits, electric propulsion gear adjusters, thrusters, series power regulators, platform loads, and a central processing unit. The solar cell array outputs two busbars via two sets of isolation diodes D1 and D2. The negative terminal of one set of isolation diodes D1 is connected to the input terminal of the electric propulsion gear regulator, and the output terminal of the electric propulsion gear regulator is connected to the input terminal of the thruster, thus forming the electric propulsion busbar. The negative terminal of the other set of isolation diodes D2 is connected to the input terminal of the series power regulator, and the output terminal of the series power regulator is connected to the platform load, thus forming the platform busbar. The electric propulsion gear adjuster includes multiple power switches and multiple grid acceleration power supplies. Each grid acceleration power supply is configured with a power switch at its input terminal, thus forming a branch. Multiple power switches are connected in series with the branches of the grid acceleration power supplies and connected in parallel to form a group. The solar cell calibration circuit acquires a set of IV curves from the solar cell calibration plate, and after normalization of temperature and solar incidence angle, IV curve a is obtained. The central processing unit acquires a set of IV curves output by the solar cell array, and after normalizing the temperature and solar incidence angle, IV curve b is obtained. A set of ground-based test solar cell IV curves were pre-injected onto the ground; The above three sets of IV curves a, b, and c are all input to the central processing unit for processing. The central processing unit controls the power switch in the electric propulsion gear regulator by processing the collected IV curves, thereby adjusting the gear of the electric propulsion thruster. The central processing unit includes a solar array curve correction module, a solar array power prediction module, and an electric propulsion gear selection module. The three sets of curves a, b, and c are all input to the solar array curve correction module for calculation and processing. The solar array curve correction module obtains the correction coefficients for voltage and current and the irradiance coefficient by calculating and processing the three sets of curves. The solar array power prediction module calculates the predicted power of the solar array based on the ground test curves using correction factors for voltage and current and irradiance. The electric propulsion gear selection module selects the operating gear of the electric propulsion based on the expected power of the solar cell array.

2. The deep space probe power system based on solar cell array power prediction according to claim 1, characterized in that: The voltages of the solar cell calibration plates under different light intensities collected by the solar cell calibration circuit are recorded as Va1~Van, and Va1~Van are multiplied by the total number of solar cells connected in series Ns; The actual output voltage of the solar cell array collected by the central processing unit is then recorded as Vb1~Vbn. The actual output voltage of the solar cell array collected by the central processing unit Vb1~Vbn is divided by the product of Va1~Van and Ns, and the average is taken to obtain the voltage correction coefficient Kv. The currents of the solar cell calibration plates collected by the solar cell calibration circuit under different light intensities are recorded as Ia1~Ian, and Ia1~Ian are multiplied by the total number of parallel solar cells Np. The actual output current of the solar cell array collected by the central processing unit is then recorded as Ib1~Ibn. The actual output current of the solar cell array collected by the central processing unit Ib1~Ibn is divided by the product of Ia1~Ian and Np, and the average is taken to obtain the current correction coefficient Ki.

3. A deep space probe power system based on solar cell array power prediction according to claim 2, characterized in that: The voltage irradiance coefficient Fv is obtained by dividing the voltage Va1 of the solar cell calibration chip collected by the solar cell calibration circuit by the voltage Vc1 of the ground-tested solar cell under the corresponding light intensity. The current irradiance coefficient Fi is obtained by dividing the current Ia1 of the solar cell calibration plate collected by the solar cell calibration circuit by the current Ic1 of the ground-based test solar cell under the corresponding light intensity.

4. A deep space probe power system based on solar cell array power prediction according to claim 3, characterized in that: In the solar cell array power prediction module, in order to predict the output power of the solar cell array at the next electric propulsion operating point, the ground test solar cell voltage under the corresponding light intensity at the operating point is recorded as Vcm, and Vcm is multiplied by the voltage correction coefficient Kv and the voltage irradiance coefficient Fv, and then multiplied by the total number of solar cells in series Ns to obtain the predicted voltage Vm of the solar cell array. The ground-based solar cell current at the corresponding light intensity at this operating point is denoted as Icm. Icm is then multiplied by the current correction factor Ki and the current irradiance factor Fi, and then multiplied by the total number of parallel solar cells Np to obtain the expected current Im of the solar cell array. The product of Vm and Im is the expected power Pm of the solar cell array.

5. A deep space probe power system based on solar cell array power prediction according to claim 4, characterized in that: In the electric propulsion gear selection module, the predicted power of the solar array obtained by the solar array power prediction module is denoted as Pm, the corresponding platform load power is denoted as Pf, the reserved power margin is denoted as P0, and the power of a single grid acceleration power supply is denoted as Pa. The difference between the predicted power of the solar array Pm obtained by the solar array power prediction module, the current platform load power Pf, and the reserved power margin P0 is used to obtain the available electric propulsion power Pd. The available electric propulsion power Pd is divided by the power of a single grid acceleration power supply Pa and rounded to obtain the number of available grid acceleration power supplies X.

6. A deep space probe power system based on solar cell array power prediction according to claim 5, characterized in that: Based on the number X of available grid acceleration power supplies calculated by the electric propulsion gear selection module, the electric propulsion gear regulator on the electric propulsion bus is controlled. By turning on the power switches at the front end of the corresponding number of grid acceleration power supplies, the thruster obtains the maximum available electric propulsion power.

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