CN113141040A

CN113141040A - Satellite power supply system

Info

Publication number: CN113141040A
Application number: CN202110450805.6A
Authority: CN
Inventors: 桑晓茹; 杨峰; 任维佳
Original assignee: Changsha Tianyi Space Technology Research Institute Co Ltd
Current assignee: Changsha Tianyi Space Technology Research Institute Co Ltd
Priority date: 2020-05-07
Filing date: 2020-05-07
Publication date: 2021-07-20
Also published as: CN113141039B; CN111293759B; CN113141039A; CN111293759A

Abstract

The invention relates to a satellite power supply system, which comprises an energy storage module, wherein the energy storage module comprises at least one unique energy storage device configured to store all electric energy generated by an energy generation module and a super capacitor bank of the unique energy supply device responding to the control of an energy management module and supplying power to a satellite load in a mode of at least two changes of voltage values, wherein the maximum state of charge value SOC of the super capacitor bank is transmitted into a current closed loop through an equalizer connected with the current closed loop and a direct current bus in a direct current signal mode through the direct current bus, so that the maximum value of the state of charge value is directly transmitted to all the super capacitor banks in the direct current bus, and the current closed loop of each super capacitor bank automatically obtains a second difference value in a second equalization coefficient. Based on modeling analysis of a plurality of groups of super capacitors in a satellite power supply system, a more effective equivalent circuit model is designed.

Description

Satellite power supply system

The invention is a divisional application of a satellite power supply system integrating energy generation, energy storage and energy management, wherein the application number is CN202010375070.0, the application date is 2020, 05 and 07, and the application type is the invention.

Technical Field

The invention relates to the technical field of satellite on-orbit power supply, in particular to a satellite power supply system.

Background

An Electric Double Layer Capacitor (EDLC) is a novel energy storage device between a conventional Capacitor and a rechargeable battery, and has the characteristics of quick charging and discharging of the Capacitor and energy storage of the battery. The super capacitor has the output characteristic of high power, can meet the requirement of a high-pulse power system, and can be used for systems which need high-power pulse power supplies, such as a satellite communication system, a radio system, electromagnetic gun transmission, unmanned aerial vehicle electromagnetic transmission and the like. However, the energy density of the conventional super capacitor still cannot meet the requirements of some satellite devices, so the conventional technology, for example, chinese patent publication No. CN103414235A, discloses a low-cost, ultra-long-life artificial satellite power storage system using solar energy as a primary energy source, which uses a buffer power storage unit with a small capacity for frequent charge and discharge and a main power storage unit with a large capacity for charge and discharge at a longer time interval to form a double power storage module, and sets the capacities of the buffer power storage unit and the main power storage unit according to a certain principle, and the main power storage unit is designed in a stepped buffer gradual change manner. The invention takes a super capacitor with no memory and long cycle life (the number of charge-discharge cycles is 3-10 ten thousand) as a buffer storage unit with small capacity. The storage battery pack with memory effect and low cycle life is used as a large-capacity main storage unit, wherein the storage battery pack has a memory effect and is a lithium ion (the number of charge-discharge cycles is 1-2 thousand) or nickel-hydrogen or nickel-cadmium (the number of cycles of a nickel-hydrogen or nickel-cadmium battery is 500-700). The invention utilizes the characteristic of high energy density of a lithium ion or nickel-hydrogen storage battery pack to make up the problem of low energy density of a super capacitor, thereby constructing a satellite power storage system with high energy density and high power density. However, in the satellite power system using the hybrid of the lithium battery pack and the super capacitor, because the characteristics of the two devices are different, the system design and the use need to be considered simultaneously, which results in a very complex scheme, and the increase of the system complexity not only results in the increase of the product cost, but also results in the increase of the failure probability, thereby reducing the reliability of the satellite power system.

The institute of applied chemistry of vinpocetine, academy of sciences, China, developed a novel colloidal supercapacitor, realized 100% utilization of active cations under kinetically allowable conditions, and developed various series of colloidal supercapacitor batteries since 2013. The energy density of the Ni-Fe colloid ion super-capacitor battery developed by Schopper university institute of chemistry, Changchun, China's institute of chemistry in 2018 can reach 350Wh/kg, the power density is 2kW/kg, and the energy density can reach 100Wh/kg and the power density is 10 kW/kg. The performance of the super capacitor battery is superior to that of the current super capacitor battery, for example, the energy density of the product of the American Maxwell super capacitor is 6Wh/kg and the power density is 12kW/kg, the energy density of the product of the American CORNING super capacitor is 9Wh/kg and the power density is 7kW/kg, and the energy density of the product of the Korean NESSCA super capacitor is 10Wh/kg and the power density is 10 kW/kg. The super capacitor developed by the vinpocetine application chemistry research in Chinese academy of sciences can basically achieve the energy density which is comparable to 150Wh/kg of a lithium battery, the working temperature range of the colloidal super capacitor is-60-80 ℃, the colloidal super capacitor meets the temperature requirement of satellite on-orbit working, the super capacitor is basically not influenced by the vacuum environment, the vibration test result meets the requirement, the colloidal super capacitor can be applied to a power supply system of a satellite after being packaged, and the satellite power supply system with high power density and high energy density can be realized without a mixed lithium battery pack. However, although the prior art already has super capacitors with high energy density and high power density, the withstand voltage of a single super capacitor is low, and a plurality of super capacitors are required to be connected in series and in parallel to improve the voltage and the energy storage capacity for satellite power supply, but due to the manufacturing process difference, different charging rates and the difference of the working environment temperature, parameters such as internal resistance, capacitance, leakage current and the like of each super capacitor are different, so that along with the long-term operation of a satellite platform, the voltages of the super capacitors are inconsistent in the series charging and discharging process of the plurality of super capacitors, the super capacitors with lower voltages may be overcharged, or the super capacitors with lower voltages are overdischarged in the discharging process, the service lives of the super capacitors are seriously damaged, and the safe operation of the satellite is influenced. Therefore, the prior art is generally equipped with an energy management system in the satellite power system to balance the super capacitor bank. The balance control of the super-capacitor energy storage system can be generally divided into single energy balance control and module energy balance control, and the single energy balance control and the module energy balance control have no substantial difference except voltage level and capacitance value of a capacitor.

Document [1] Mishra R, Saxena R. comprehensive Review of Control Schemes for batteries and Super-capacitor Energy Storage System [ C ]. 20177 th International Conference on Power Systems (ICPS),2017,702 707 discloses a common equalization Control strategy for supercapacitors. The existing balance control strategy can be divided into an active balance strategy, a passive balance strategy and a dynamic balance control strategy based on a cascade power converter. The passive equalization strategy needs to consume redundant energy in a form of heat by using an external circuit, and is an energy consumption type strategy, and is mainly realized by an equalization resistor or a voltage stabilizing diode. However, although the passive equalization strategy is easy to implement, the equalization efficiency is not high, the equalization speed is slow, and the system is prone to generate heat seriously, so that the passive equalization strategy is suitable for a low-power energy storage system or an occasion with low requirement on the equalization speed, and is not suitable for a satellite energy storage system. Active equalization strategies require the use of external equalization circuitry to transfer energy in high energy devices to low energy devices. The implementation of the external equalization circuit may be divided according to whether or not there is an isolation transformer. The transformer-free active equalization strategy is to transmit energy from bottom to top step by using a Boost converter, but the equalization speed of the energy equalization strategy is low, and the equalization strategy can be improved by adopting a parallel equalization capacitor mode, so that the equalization speed of a voltage-multiplying equalization circuit can be effectively improved, or the equalization speed is improved by changing the input time of a low-voltage energy storage module on the basis of the traditional equalization circuit. The above transformer-less active equalization strategy can reduce the loss of equalization energy, and the cost and volume of the energy equalization system are small. However, as the number of super capacitors connected in series increases, the equalization efficiency cannot be guaranteed. The active balancing strategy based on the isolation transformer can improve the conversion efficiency of energy between non-adjacent super capacitors, and generally, active balancing is realized by the balancing strategy based on the multi-winding transformer, but with the increase of the number of the super capacitors connected in series, the isolation transformer with numerous windings is difficult to manufacture, so the active balancing strategy based on the isolation transformer is only suitable for the system with the small number of the super capacitors connected in series. The energy balance control strategy based on the cascade power converter is to realize energy balance control among the energy storage modules by directly utilizing system current in the dynamic charging and discharging process of the system so as to simplify the structure of the balance system. Specifically, energy storage and energy balance control are normalized, and the Charge and discharge control is performed on the State of Charge (SOC) of the energy storage module. However, the above-mentioned balance control strategy uses a cascaded modular dc converter, and structurally belongs to an Input-series Output-series (ISOS) system, and the voltage-sharing of its sub-modules generally adopts a multi-closed-loop control strategy in a current differential form, which has a high requirement on system parameters and is easily influenced by the current of the main power circuit.

Furthermore, on the one hand, due to the differences in understanding to the person skilled in the art; on the other hand, since the inventor has studied a lot of documents and patents when making the present invention, but the space is not limited to the details and contents listed in the above, however, the present invention is by no means free of the features of the prior art, but the present invention has been provided with all the features of the prior art, and the applicant reserves the right to increase the related prior art in the background.

Disclosure of Invention

In the prior art, the satellite power supply system with the lithium battery pack and the super capacitor is used, and due to the fact that the characteristics of the two devices are different, the system design and the use need to be considered simultaneously, the complexity of the system is improved, the product cost is high, the failure probability of the system is increased due to the excessively complex system, and the reliability of the satellite system is seriously reduced. Although the satellite platform is powered by the super capacitor group consisting of the super capacitors with high power density and high energy density, the improvement of the complexity of the system can be avoided, for example, the super capacitors developed by the vinpocetine application chemistry in the Chinese academy of sciences are used, and the parameters of each super capacitor are different due to the manufacturing process difference, different charging rates and the difference of the working environment temperature, so that the voltages of the super capacitors are inconsistent in the serial charging and discharging process of the super capacitors along with the long-term operation of the satellite platform, the super capacitors with lower voltages can be overcharged, or the super capacitors with lower voltages are overdischarged in the discharging process, the service lives of the super capacitors are seriously damaged, and the safe operation of the satellite is influenced. Therefore, in the prior art, the voltage of the plurality of super capacitors is kept consistent in the charging and discharging process by adopting a super capacitor voltage balancing mode, and overcharging or overdischarging is avoided. The existing balancing technology of super capacitors usually adopts an active balancing control strategy or an energy balancing control strategy based on a cascade power converter, but no matter the active balancing strategy or the energy balancing control strategy based on the cascade power converter is adopted, a multi-closed-loop control strategy in a current or voltage differential form is needed to realize voltage balancing, and the multi-closed-loop control strategy relates to an external balancing circuit, so that the energy balancing of an energy storage system and the system power control are kept independent, which not only causes the energy loss of the system to be increased, but also weakens the operability of the control system, thereby reducing the overall reliability of the system, and the balancing efficiency cannot be ensured along with the increase of the number of the super capacitors connected in series.

In view of the above problems, the present invention provides a modular satellite power system integrating energy generation, energy storage and energy management, which at least comprises an energy generation module, an energy storage module and an energy management module. The energy storage module stores the electric energy generated by the energy generation module and supplies power to the on-satellite load based on the control of the energy management module. The energy storage module at least comprises at least one super capacitor group formed by a plurality of super capacitors. The super capacitor bank is configured to be a unique energy storage device for storing all electric energy generated by the energy generation module and a unique energy supply device for supplying power to the on-board load in at least two ways of changing voltage values in response to the control of the energy management module. The energy management module at least comprises a voltage closed loop which transmits signals in a direct current mode through a direct current bus and is shared by all the super capacitor groups, at least one current closed loop which is positioned in the voltage closed loop and forms a closed loop with each super capacitor group respectively, and an equalizer which is connected with the current closed loop and the direct current bus. The method is used for solving the problems that energy loss is increased and the control system is poor in operability due to the fact that voltage and current closed-loop control strategies which are independent of each other are adopted in the existing satellite power storage system. The technical effect that the communication line in the prior art is replaced by the connection with the direct current bus on the basis of simplifying the structure and reducing the energy loss to a certain extent through the shared voltage closed loop, and the system can be ensured to have the capability of stabilizing the satellite power supply system because the shared voltage closed loop is connected with the direct current bus and the direct current signal is used for transmitting the charge state value information of the super capacitor bank and the reference current signal generated by the voltage closed loop. The traditional multi-closed-loop control system transmits voltage signals or current signals by using a communication line, because a direct current bus is used for transmitting signals, and the carrier or information quantity of the signals is the amplitude of direct current, the direct current bus generates voltage drop, the voltage drop is easy to change along with the length of the direct current bus, and the transmission of the direct current signals is limited, so that the traditional multi-closed-loop control system transmits information by using digital signals. However, the adoption of digital signals requires additional communication lines for equalization to transmit the digital signals, the increase of the number of super capacitor banks inevitably leads to the complication of the whole satellite communication line, and the generation of huge communication data by the digital signals also brings computational burden to the processor. The reference current signal required by the current closed loop is transmitted through the direct current bus in the voltage closed loop, the communication data volume and the processing cost can be greatly reduced in a mode of simulating current transmission information, the problem of low anti-interference capability caused by transmission loss can be greatly reduced due to the fact that the direct current bus of the satellite power supply system is short, and therefore the complexity of a circuit and huge data information are avoided under the condition that part of anti-interference capability is sacrificed.

Preferably, the energy management module is configured to output a reference current signal through the voltage closed loop based on the voltage value fed back by the dc bus and a reference voltage signal. The energy management module is configured to adjust the equalizer output equalization parameters for each supercapacitor bank in response to a difference between the reference current signal and a system current feedback value. The energy management module is configured to generate a driving signal for equalizing charge of the super capacitor bank through the current closed loop based on the equalization parameter. The method is used for solving the problem of overcharge or overdischarge of the super capacitor bank in the energy balancing process of the super capacitor bank in the energy storage module. The technical effect achieved is that voltage fed back by the direct current bus and reference voltage signals set based on the number and the specification of the super capacitor sets are input into a voltage closed loop. A voltage regulator within the voltage closed loop generates a reference current signal. And combining a difference value generated by the reference current signal and the system current feedback value with the balance parameters generated by the equalizer and corresponding to each super capacitor bank, and sending the result into the current closed loop of each super capacitor bank. And the current regulator in the current closed loop generates the duty ratio of the super capacitor bank according to the input result, the duty ratio is in proportional relation with the charge state value of the super capacitor bank, and therefore the energy balance of each super capacitor bank can be controlled through the duty ratio.

Preferably, in the case that the energy generation module charges the energy storage module, the equalizer is configured to: and acquiring the state of charge value of each super capacitor group in an online estimation mode based on the voltage value and the current value fed back by the voltage closed loop and the current closed loop, so as to construct an equalization parameter which at least comprises a first equalization coefficient and a second equalization coefficient and the sum of which is always kept at a constant value. The first equalization coefficient is configured as a ratio of a first difference value of the corresponding supercapacitor group to a sum of first difference values of all supercapacitor groups, and the sum of the first equalization coefficients of all the supercapacitor groups is the constant value. The first difference is defined by a difference between a state of charge value of the respective supercapacitor bank and the fixed value. The second equalization coefficients comprise at least a second difference defined by the difference between the maximum and minimum of the state of charge values of all the supercapacitor groups and a first dynamic coefficient for defining the second difference such that the sum of the second equalization coefficients of all the supercapacitor groups remains zero. The technical scheme is used for solving the problem that the balancing efficiency cannot be guaranteed along with the increase of the number of the super capacitor sets. In the process of balancing the super capacitor bank, along with the continuous balancing of energy among the super capacitor banks, the charge state values of the super capacitor banks gradually tend to be consistent. The energy balance is carried out based on the charge state values of the super capacitors, and the balance is carried out according to the difference of the charge state values of the super capacitors. If the difference of the state of charge values of the super capacitors is gradually reduced, the equalizing speed of the energy management module is gradually reduced. And with the increase of the number of the super capacitor sets, the number of the super capacitor sets with similar charge state values is increased, and the balancing speed of the energy management module is greatly reduced. The equalization parameter adopted in the prior art is generally the first equalization coefficient in the present invention, that is, the first equalization coefficient is defined according to the state of charge values between the respective supercapacitor sets. Generally, the sum of the first equalization coefficients of the super capacitor sets is a fixed value 1, which is convenient for the control setting of the equalizer and the demodulation of the equalization parameters by the current closed loop. The second equalization coefficient is linear superposition of the first equalization coefficients, and the purpose to be achieved is to further amplify the difference between different first equalization coefficients according to the difference of the state of charge values of the super capacitor bank, so that the equalization speed is accelerated under the condition that the state of charge values of the super capacitor bank tend to be consistent. In addition, the equalizers respectively connected with the current closed loop and the direct current bus can transmit the maximum state of charge values of the super capacitor sets into the current closed loop through the direct current bus in the form of direct current signals, so that the maximum values of the state of charge values of all the super capacitor sets can be directly transmitted in the direct current bus, and the current closed loop of each super capacitor set can automatically acquire a second difference value in a second equalization coefficient. Through the setting mode, the direct current bus is used for replacing a communication line to directly transmit the charge state values of the super capacitors in a direct current signal mode, the information amount processed by the equalizer is further simplified, and the charge state values of key parameters for determining equalization control are transferred to the direct current bus and the current closed loops corresponding to the super capacitor sets, so that the charge state values are not required to be processed by the equalizer in a centralized mode, and the equalization capacity of the energy management module is not influenced after any super capacitor set is stopped due to faults. And because the direct current carrier transmits signals of the state of charge values, the sum of the signals is a fixed value, and therefore the anti-interference capability of the direct current signals can be further improved by utilizing the proportional amplifier.

Through the arrangement mode, in the process that the satellite power supply system uses the energy storage module only consisting of the super capacitor to perform multi-closed-loop energy balance control, the reference current signal required by the current closed loop is transmitted through the direct current bus in the voltage closed loop, the communication data volume and the processing cost are greatly reduced in a mode of simulating current transmission information, and the balance speed is accelerated by further amplifying the difference of the second balance coefficient to the charge state value of the super capacitor group. And the sum of the second equalization coefficients is zero, and the sum of the first equalization coefficients is a fixed value of 1, so that the energy management module can strictly track the current reference signal, and in addition, as the number of the super capacitor banks increases, the equalization speed based on the state of charge value is also related to the number of the super capacitor banks, but the first equalization coefficients and the second equalization coefficients are mainly determined by the state of charge value, which indicates that the number of the cascaded super capacitor banks does not affect the equalization speed of the energy management module, and the only effect on the equalization speed of the energy management module is the state of charge value of the super capacitor banks, so that the equalization efficiency of the energy management module can still be ensured under the condition that the number of the super capacitor banks increases through the setting of the second equalization coefficients.

According to a preferred embodiment, said first dynamic coefficient comprises at least a first coefficient and a second coefficient proportional to said second difference. The equalizer is configured to: a first coefficient that is summed to a zero value is constructed based on a difference between the average of the first differences for the supercapacitor bank and the first difference for the corresponding supercapacitor bank. Constructing a second coefficient that linearly amplifies the second equalization coefficient based on the second difference.

According to a preferred embodiment, in the case where the energy storage module supplies power to the on-board load, the equalizer is configured to: and constructing an equalization parameter which at least comprises a third equalization coefficient and a fourth equalization coefficient and always keeps a constant value in sum on the basis of the acquired state of charge value of each super capacitor bank. The third equalization coefficient is configured as a ratio of the state of charge value of the corresponding supercapacitor group to the sum of the state of charge values of all the supercapacitor groups. And the sum of the third equalization coefficients of all the super capacitor sets is the fixed value. The fourth equalization coefficient comprises at least a second difference defined by a difference between a maximum value and a minimum value of the state of charge values of all of the supercapacitor groups. The fourth equalization coefficients further comprise a second dynamic coefficient for defining the second difference such that the sum of the fourth equalization coefficients of all of the supercapacitor groups remains at zero.

According to a preferred embodiment, said second dynamic coefficient comprises at least a third coefficient and a fourth coefficient proportional to said second difference. The equalizer is configured to: and constructing a third coefficient keeping the sum to be zero based on the difference between the state of charge value of the corresponding super capacitor group and the average value of the state of charge of all the super capacitor groups. Constructing a fourth coefficient that linearly amplifies the third equalization coefficient based on the second difference.

According to a preferred embodiment, in the case where the energy generation module charges the energy storage module or the energy storage module supplies power to the on-board load, the energy management module is configured to: controlling, by the equalizer, the second equalization coefficient and the fourth equalization coefficient to gradually increase as the second difference decreases.

According to a preferred embodiment, in the case where the energy management module is responsive to a reference current signal delivered by the voltage closed loop, the energy management module is configured to: and controlling the equalizer to transmit the state of charge value of the super capacitor bank to the current closed loop through the direct current bus in the form of a direct current signal. The current closed loop is configured to: and re-determining the reference current signal transmitted by the voltage closed loop based on the DC signal with the highest state of charge value.

According to a preferred embodiment, in the case where the equalizer performs equalization control based on the duty ratio generated by the current closed loop, the equalizer is configured to: and under the condition that the energy generation module charges the energy storage module, controlling the super capacitor bank with a low charge state value to charge at a duty ratio larger than that of the super capacitor bank with a high charge state value. And under the condition that the energy storage module supplies power to the on-satellite load, the super capacitor bank with a low charge state value is controlled to discharge at a duty ratio smaller than that of the super capacitor bank with a high charge state value. And under the condition that the state of charge values of all the super capacitor banks are consistent, controlling a current closed loop to charge or discharge the super capacitor banks at the same duty ratio.

The invention also provides a configuration method of the modular satellite power supply system, which comprises the following steps: the energy storage module of at least one super capacitor group consisting of a plurality of super capacitors stores the electric energy generated by the energy generation module and supplies power to the on-satellite load based on the control of the energy management module; the super capacitor bank serves as a unique energy storage device and a unique energy supply device for storing all electric energy generated by the energy generation module and responds to the control of the energy management module to supply power to the on-satellite load in at least two ways of changing voltage values.

Preferably, the energy management module performs the steps of:

outputting a reference current signal through a voltage closed loop based on a voltage value fed back by the direct current bus and a reference voltage signal;

adjusting an equalizer to output an equalization parameter of each super capacitor bank in response to a difference between the reference current signal and a system current feedback value;

and generating a driving signal for equalizing charging of the super capacitor bank through current closed loop based on the equalization parameter.

According to a preferred embodiment, in case the energy generation module charges the energy storage module, the equalizer performs the following steps:

and acquiring the state of charge value of each super capacitor group in an online estimation mode based on the voltage value and the current value fed back by the voltage closed loop and the current closed loop, so as to construct an equalization parameter which at least comprises a first equalization coefficient and a second equalization coefficient and the sum of which is always kept at a constant value. The first equalization coefficient is a ratio of a first difference of the corresponding super capacitor bank to a sum of first differences of all the super capacitor banks. The sum of the first equalization coefficients of all the super capacitor sets is the fixed value. The first difference is defined by a difference between a state of charge value of the respective supercapacitor bank and the fixed value. The second equalization coefficient comprises at least a second difference defined by a difference between a maximum value and a minimum value of the state of charge values of all of the supercapacitor groups. The second equalization coefficients further comprise a first dynamic coefficient for defining the second difference such that the sum of the second equalization coefficients of all of the supercapacitor groups remains at zero.

Drawings

FIG. 1 is a block schematic diagram of a preferred embodiment of the satellite power system of the present invention;

FIG. 2 is a schematic structural diagram of a preferred embodiment of the energy management module of the present invention;

FIG. 3 is a classical model of a super capacitor equivalent circuit;

FIG. 4 is a simplified model of a super capacitor equivalent circuit;

FIG. 5 is a schematic circuit diagram of the principle of operation of the supercapacitor pack of the present invention; and

fig. 6 is a flowchart illustrating steps of a satellite power configuration method according to the present invention.

List of reference numerals

10: the energy generation module 20: energy storage module

30: the energy management module 40: on-board load

201: supercapacitor pack 202: first bridge arm

203: second bridge arm 301: voltage closed loop

302: current closed loop 303: equalizer

304: the boost module 305: voltage reduction module

306: proportion link 3011: voltage regulator

3012: reference voltage signal 3013: voltage value fed back by DC bus

3021: current regulator 3022: reference current signal

3023: system current feedback value 3024: waveform generator

SOC: state of charge value Req: equivalent parallel resistance

C: and the capacitance Res: equivalent series resistance

Detailed Description

The following detailed description is made with reference to the accompanying drawings.

The background knowledge of the embodiments and the appearing technical terms are explained first.

Since the voltage of the single super capacitor is low, a plurality of super capacitors are connected in series to increase the voltage and increase the capacity of stored energy. For a satellite power supply system, according to the size, weight and load of a satellite, a large satellite may need to divide a plurality of super capacitors into groups, and connect the super capacitors in parallel or in series to multiply the energy stored in the super capacitors, so as to supply power to the satellite. The super capacitor is applied to a satellite power supply system, so that the super capacitor has a complex resistance-capacitance network, and the equivalent resistance and the capacitance of each branch have difference. In fact, the charge amount stored by the super capacitor is related to the charge state value SOC, the voltage level, the operation time and other factors, so that modeling analysis needs to be performed on the energy storage system of the super capacitor, and at present, super capacitor modeling is mainly based on an RC impedance network. The modeling types include an RC transmission line model and an equivalent circuit model. Due to the short response time of the super capacitor energy storage system, the dynamic charge and discharge process is usually only tens of seconds. When the dynamic current of the system is directly utilized to carry out balance control on the super capacitor, the long-time parameter in the multi-stage RC branch circuit has little significance to the balance control, so that the equivalent circuit model adopting the lumped parameter is more effective. The simplified RC equivalent circuit model is shown in fig. 3 and 4.

The simplified circuit structure shown in fig. 3 is referred to as a classical model in a super capacitor energy storage system. The model is formed by connecting an ideal capacitor C with an equivalent series resistor Res with a smaller resistance value in series and simultaneously connecting the ideal capacitor C with an equivalent parallel resistor Rep with a larger resistance value in parallel. The equivalent series resistance Res will make the dynamic efficiency of the super capacitor less than 1, while it can be used to describe the dynamic loss of the super capacitor. The equivalent parallel resistor Rep is used for describing the leakage current characteristic of the super capacitor in a long-time static energy storage state.

The classical model in fig. 3 can be further simplified to the simplified model shown in fig. 4. The model consists of only one ideal capacitance and the equivalent series resistance Res. The equivalent series resistance Res represents the internal loss of the super capacitor, the voltage drop generated in the dynamic process and the constraint condition of the maximum working current of the super capacitor, and the model only considers the dynamic characteristics of charging and discharging of the super capacitor. Therefore, a simplified model can be adopted for analysis when the short-time charging and discharging dynamic characteristics of the super capacitor are researched.

The state of charge value SOC of the super capacitor is used for describing the amount of charge stored in the current state of the super capacitor. The method for calculating the SOC of the super capacitor comprises two forms of charge and electric energy. The two calculation methods define the calculation form of the SOC of the super capacitor from different angles, and both can reflect the current storage capacity of the super capacitor. The following examples employ a state of charge SOC calculation method based on a charge form as shown in the following equation:

therein, SOC_gThe state of charge value of the supercapacitor is calculated based on the charge. Current of Qc (-) representationThe amount of charge stored by the supercapacitor. u. of_ocvThe present open circuit voltage of the super capacitor is shown. u. of_ratedThe nominal voltage of the supercapacitor is indicated. It should be noted that the super capacitor indicated by the above formula may be a single super capacitor, or may be the super capacitor group 201.

The super capacitor group 201 is formed by connecting a plurality of single super capacitors in series and parallel. The port voltage of the super capacitor bank 201 can be detected by the voltage detection element, but in the case of large current charging and discharging, the voltage drop of the equivalent series resistance Res of the super capacitor bank 201 will cause the port voltage of the super capacitor bank 201 to be greater than the voltage across the super capacitor bank 201, and in the case of discharging, the port voltage of the super capacitor bank 201 will be less than the voltage across the super capacitor bank 201, so the voltage drop generated by the equivalent series resistance Res in the super capacitor bank 201 cannot be ignored. In order to accurately estimate the state of charge SOC of the supercapacitor pack 201, online estimation of relevant parameters of the supercapacitor pack 201 is required.

The online estimation method of the state of charge SOC of the super capacitor bank 201 may adopt a Kalman Filter (KF) algorithm commonly used in the control system to perform estimation. From this, an equivalent equation of state of the discrete-state supercapacitor set 201 can be obtained, as shown in the following equation:

u_sc(m)＝u_c(m)+i_sc(m)R_es(m)+v(m)

wherein u is_c(m +1) represents the voltage across the supercapacitor group 201 at the (m +1) th sampling time. u. of_c(m) represents the voltage across the supercapacitor pack 201 at the mth sampling instant. C (m) represents the capacitance value of the supercapacitor set 201 at the mth sampling time. i.e. i_sc(m) represents the port current of the supercapacitor pack 201 at the mth sampling instant. T is_cRepresenting the sampling time. u. of_sc(m) represents the port voltage of the supercapacitor pack 201 at the mth sampling instant. u. of_c(m) represents the mth sampling time super capacitorThe voltage across the bank 201. R_es(m) represents the equivalent resistance of the supercapacitor pack 201. w (m), v (m) represent white gaussian noise with a mean value of 0, and satisfy self-independence and mutual independence. Through the state variables based on the Kalman filtering algorithm in the discrete state and the equivalent state equation of the discrete-state supercapacitor set 201, a dual observer based on the Kalman filtering algorithm can be constructed to identify the voltage and relevant parameters of the supercapacitor set 201. Because the parameters of the super capacitor change slowly, the parameter observation and model can adopt independent sampling time to reduce the calculation amount.

The principle of dynamic balancing of energy of a supercapacitor is shown in fig. 5. The super capacitor bank 201 in the energy storage module 20 is connected to the energy management module 30 through a first bridge leg 202 and a second bridge leg 203. First leg 202 and second leg 203 each include at least one transistor and one diode. When supercapacitor set 201 is charged and discharged, a current flows through first arm 202 and supercapacitor set 201, that is, first arm 202 is in an on state, and second arm 203 is in an off state. When energy management module 30 controls energy storage module 20 to charge, a current flows through diodes connected in anti-parallel to first leg 202 to charge supercapacitor set 201, and the flow of the current is shown by a dotted line in fig. 5. When energy management module 30 controls energy storage module 20 to discharge, first arm 202 is in an on state, second arm 203 is in an off state, and supercapacitor pack 201 discharges through first arm 202, and the flow of the circuit is shown by a solid line in fig. 5. When first bridge arm 202 is in an off state and second bridge arm 203 is in an on state, second bridge arm 203 is directly connected with energy management module 30, so that supercapacitor set 201 is in a bypass state and the voltage is maintained unchanged. From the above analysis, it can be seen that the average current i flowing through the super capacitor bank 201_sciAnd system current i_LThe relationship between them is shown as follows:

i_sci＝d_ii_L

wherein d is_iShown is the duty cycle of the ith supercapacitor bank 201. The duty ratio represents that the super capacitor is in one control periodThe proportion of the on time of the first leg 202 corresponding to the group 201 to the control period. Energy management module 30 controls the turning on and off of supercapacitor pack 201 by calculating the generated duty cycle. According to the above equation, the average current flowing through each supercapacitor set 201 in the system is as follows:

i_sc1：i_sc2：...：i_sck＝d₁：d₂：...：d_k

in fact, the coulomb's law shows that the amount of stored charge of the capacitor is linearly related to the charging and discharging current and time thereof, so that the relationship between the duty ratio of each supercapacitor set 201 and the state of charge value SOC thereof can be obtained:

d₁：d₂：...：d_k＝ΔSOC₁：ΔSOC₂：...：ΔSOC_k

wherein, Δ SOC_kIndicating the amount of change in state of charge SOC of the kth supercapacitor pack 201. Due to the adoption of the modularized structure, system currents flowing through the super capacitor groups 201 are the same, so that the change of the SOC value of the super capacitor groups can be controlled through the duty ratio of each super capacitor group 201, and the balance control among the super capacitor groups 201 can be realized through the adjustment of the duty ratio. In the charging mode of the energy generation module 10 for the energy storage module 20, the supercapacitor set 201 with the higher SOC value should be charged with a smaller average current, and the supercapacitor set 201 with the lower SOC value should operate at a larger average current. In the discharging mode of the energy storage module 20, the energy management module 30 should perform duty cycle control so that the supercapacitor set 201 with a higher SOC value should be discharged at a higher average current, and the supercapacitor set 201 with a lower SOC value should be discharged at a lower average current. When the super capacitor bank 201 is in a bypass state, the triode of the second bridge arm 203 and the anti-parallel diode thereof can provide a conducting path for the system current, so that on the premise of ensuring that the satellite power supply system stabilizes the dc bus voltage, the energy management module 30 can adjust the working average current according to the state of charge (SOC) value of each super capacitor bank 201, thereby adjusting the working average current of each super capacitor bank 201 in the satelliteAnd the SOC balance control of the super capacitor bank 201 is realized in the dynamic process of charging and discharging of the power supply system.

Dynamic balancing of the energy of the super capacitor bank 201 is achieved by the energy management module 30. Energy management module 30 includes at least a voltage closed loop 301 and a current closed loop 302. The voltage closed loop 301 generally includes a voltage regulator 3011, a reference voltage signal 3012, and a dc bus fed back voltage value 3013. Current closed loop 302 generally includes a current regulator 3021, a reference current signal 3022, and a system current feedback value 3023. Preferably, the current closed loop 302 further comprises a waveform generator 3024 connected to the current regulator 3021. The waveform generator 3024 may be a triangular waveform generator.

The energy management module 30 operates on the principle that the voltage closed loop 301 is used to control the voltage of the dc bus. The voltage closed loop 301 is connected with the current closed loop 302, and the voltage closed loop 301 is at the outer layer of the current closed loop 302, as shown in fig. 2. Preferably, in the voltage closed loop 301, the inputs of the voltage regulator include at least a reference voltage signal 3012 and a dc bus fed back voltage value 3013. The reference voltage signal 3012 is set according to the information of the energy storage module 20, and is used as a reference parameter to equalize the super capacitor bank 201 in the energy storage module 20. Preferably, the difference between the reference voltage signal 3012 and the voltage value 3013 fed back by the dc bus is input to the voltage regulator 3011. The voltage regulator 3011 calculates an output reference current signal 3022, which is transmitted to the current closed loop 302. A difference signal generated by reference current signal 3022 and the fed back system current 3023 is input to current regulator 3021. Current regulator 3021 calculates to generate a corresponding duty cycle and then compares it with waveform generator 3024 to generate a drive signal to drive the supercapacitor bank 201. Alternatively, the duty ratio generated by the current regulator 3021 may be modulated by a Pulse Width Modulation (PMW) modulator, thereby generating a Modulation signal for the super capacitor bank 201. Preferably, the voltage regulator 3011 may be a voltage PID regulator. The current regulator 3021 may be a current PID regulator.

Preferably, the energy management module 30 may be connected to the energy storage module 20 through a bidirectional DC-DC converter. The bidirectional DC-DC converter mainly realizes the transmission of energy among the super capacitor sets 201 and has the characteristics of low voltage and large current. In addition, the DC bus may also be connected to the on-board load 40 via a bidirectional DC-DC converter.

Example 1

As shown in fig. 1 and 2, the present embodiment provides a modular satellite power system integrating energy generation, energy storage, and energy management. The satellite power system at least comprises an energy generation module 10, an energy storage module 20 and an energy management module 30. The energy storage module 20 stores the electric energy generated by the energy generation module 10. The energy storage module 20 supplies power to the on-board loads 40 based on control of the energy management module 30. Preferably, the energy storage module 20 comprises at least one supercapacitor pack 201. The supercapacitor pack 201 is composed of a plurality of supercapacitors. The super capacitor bank 201 is configured as the only energy storage device that stores the entire electric energy generated by the energy generation module 10. Preferably, the supercapacitor pack 201 is also configured as the only powering device that supplies power to the on-board load 40 in response to the control of the energy management module 30. Preferably, the super capacitor bank 201 supplies power to the on-satellite load 40 in at least two ways of varying voltage values. The at least two ways of varying the voltage value may be to supply the on-board load 40 in a step-up and step-down manner. Preferably, energy management module 30 includes at least a boost module 304 and a buck module 305. The boost module 304 may be a boost type DC-DC converter. The voltage dropping module 305 may be a buck DC-DC converter. Preferably, the energy generation module 10 may be a solar cell windsurfing board.

Preferably, energy management module 30 includes at least a voltage closed loop 301, at least one current closed loop 302, and an equalizer 303. Preferably, the voltage closed loop 301 transmits signals in the form of direct current through a direct current bus. The voltage closed loop 301 is a voltage closed loop 301 shared by all the supercapacitor sets 201, as shown in fig. 2. The current closed loop 302 is within the voltage closed loop 301. The current closed loop 302 forms a closed loop with each super capacitor bank 201. The equalizer 303 is connected to the current closed loop 302 and the dc bus. The problems that energy loss is increased and the operability of a control system is poor due to the fact that voltage and current closed-loop control strategies which are independent of each other are adopted in the existing satellite power storage system are solved. The present embodiment replaces the communication line in the prior art by the connection with the dc bus by the shared voltage closed loop 301 based on a certain simplification of the structure and reduction of the energy loss. Since the common voltage closed loop 301 is connected with the dc bus and transmits the state of charge value of the super capacitor bank 201 and the reference current signal 3022 generated by the voltage closed loop 301 by using the dc signal, the system can be ensured to have the capability of stabilizing the satellite power system. The traditional multi-closed-loop control system transmits voltage signals or current signals by using a communication line, because a direct current bus is used for transmitting signals, and the carrier or information quantity of the signals is the amplitude of direct current, the direct current bus generates voltage drop, the voltage drop is easy to change along with the length of the direct current bus, and the transmission of the direct current signals is limited, so that the traditional multi-closed-loop control system transmits information by using digital signals. However, the adoption of digital signals requires additional communication lines for equalization to transmit the digital signals, the increase of the number of the super capacitor banks 201 inevitably leads to the complication of the whole satellite communication line, and the generation of huge communication data by the digital signals also brings computational burden to the processor. The reference current signal 3022 required by the current closed loop 302 is transmitted through the direct current bus in the voltage closed loop 301, so that the communication data volume and the processing cost can be greatly reduced in a mode of simulating current transmission information, and the problem of low anti-interference capability caused by transmission loss can be greatly reduced due to the short length of the direct current bus of the satellite power supply system, so that the complexity of lines and huge data information can be avoided under the condition of sacrificing part of anti-interference capability.

Preferably, the energy management module 30 is configured to output a reference current signal 3022 through the voltage closed loop 301 based on the voltage value 3013 fed back by the dc bus and the reference voltage signal 3012. Energy management module 30 is configured to adjust equalizer 303 to output an equalization parameter for each supercapacitor bank 201 in response to a difference between reference current signal 3022 and system current feedback value 3023. Energy management module 30 generates a drive signal for equalizing charge of supercapacitor group 201 through current closed loop 302 based on the equalization parameter. In the process of realizing energy balance of the super capacitor bank 201 in the energy storage module 20, the problem of overcharge or overdischarge of the super capacitor bank 201 is easily caused. The present embodiment utilizes the voltage fed back by the dc bus and the reference voltage signal 3012 set based on the number and specification of the super capacitor sets 201 to input into the voltage closed loop 301. A voltage regulator 3011 within the voltage closed loop 301 generates a reference current signal 3022. The difference generated by reference current signal 3022 and system current feedback value 3023 is combined with the equalization parameters generated by equalizer 303 for each supercapacitor bank 201 and the result is fed into current closed loop 302 of each supercapacitor bank 201. Current regulator 3021 within current closed loop 302 generates a duty cycle of ultracapacitor bank 201 based on the input results, the duty cycle being proportional to state of charge value SOC of ultracapacitor bank 201, and thus energy balance of each ultracapacitor bank 201 can be controlled by the duty cycle.

Preferably, in the case where the equalizer 303 performs the equalization control based on the duty ratio generated by the current closed loop 302, the equalizer 303 is configured to: when the energy generation module 10 charges the energy storage module 20, the super capacitor bank 201 with a low state of charge value is controlled to charge at a duty ratio larger than that of the super capacitor bank 201 with a high state of charge value. Preferably, a supercapacitor pack 201 with a low state of charge value refers to a supercapacitor pack 201 with a lower state of charge value. And under the condition that the energy storage module 20 supplies power to the on-board load 40, controlling the super capacitor bank 201 with the low charge state value to discharge at a duty ratio smaller than that of the super capacitor bank 201 with the high charge state value. And controlling the current closed loop 302 to charge or discharge the super capacitor bank 201 at the same duty ratio under the condition that the state of charge values of all the super capacitor banks 201 are consistent.

Preferably, in case the energy generation module 10 charges the energy storage module 20, the equalizer 303 is configured to: the state of charge value of each supercapacitor set 201 is obtained in an online estimation mode based on the voltage value and the current value fed back by the voltage closed loop 301 and the current closed loop 302, so that an equalization parameter which at least comprises a first equalization coefficient and a second equalization coefficient and is always kept at a constant value in sum is constructed. Preferably, the first equalization coefficient is configured as a ratio of the first difference of the corresponding supercapacitor group 201 to the sum of the first differences of all supercapacitor groups 201. All of the supercapacitor sets 201The sum of the first equalization coefficients is constant. The constant value may be 1. The first difference is defined by the difference between the state of charge value and the fixed value of the respective supercapacitor pack 201. Preferably, the first equalizing coefficient F₁Can be represented by the following formula:

wherein, 1-SOC_iIs the first difference.

Is the sum of the first differences of all the supercapacitor sets 201. k is the number of supercapacitor sets 201. SOC_iIs the state of charge value of the corresponding supercapacitor pack 201.

Preferably, the second equalization coefficients comprise at least the second difference and the first dynamic coefficient. The second difference is defined by the difference between the maximum and minimum of the state of charge values for all supercapacitor groups 201. The second difference represents the degree of variation in state of charge value SOC among supercapacitor group 201. The first dynamic coefficient is used to define the second difference such that the sum of the second equalization coefficients of all ultracapacitor banks 201 remains at a zero value. Preferably, the first dynamic coefficient includes at least a first coefficient and a second coefficient. The second coefficient is proportional to the second difference. Preferably, equalizer 303 is configured to construct a first coefficient that is kept at a zero value in sum based on the difference between the average of the first differences of supercapacitor group 201 and the first differences of the corresponding supercapacitor group 201. The equalizer 303 is configured to construct a second coefficient that linearly amplifies the second equalization coefficient based on the second difference. Preferably, the second equalizing coefficient F₂Can be represented by the following formula:

therein, SOC_dIs the second difference.

Is the first dynamic coefficient.

Is the first coefficient. m is₁The value of the second coefficient is related to the second difference. m is₁Taking a positive integer, e.g. m in the case of a second difference of 0.4₁The value may be 4. m is₂The gain factor is typically 2.

Preferably, the equalization parameter may be represented by the following formula:

in a preferred embodiment, in the case where the energy storage module 20 supplies power to the on-board load 40, the equalizer 303 is configured to: and (3) establishing an equalization parameter based on the acquired state of charge value of each super capacitor group 201. The equalization parameters include at least a third equalization coefficient and a fourth equalization coefficient. The sum of the equalization parameters of each supercapacitor group 201 is always kept constant. Preferably, the third equalization coefficient is configured as a ratio of the state of charge value of the corresponding supercapacitor group 201 to the sum of the state of charge values of all supercapacitor groups 201. The sum of the third equalization coefficients of all the super capacitor sets 201 is a constant value. The third equalization coefficient may be represented by:

preferably, the fourth equalization coefficient includes at least the second difference and the second dynamic coefficient. The second difference is defined by the difference between the maximum and minimum of the state of charge values for all supercapacitor groups 201. The second dynamic coefficient is used to define a second difference such that the sum of the fourth equalization coefficients of all supercapacitor groups 201 remains zero. The second dynamic coefficient includes at least a third coefficient and a fourth systematic number. The fourth coefficient is proportional to the second difference. Preferably, equalizer 303 is configured to construct a third coefficient that sums to a value of zero based on the difference between the state of charge value of the respective supercapacitor bank 201 and the average of the state of charge of all supercapacitor banks 201. The equalizer 303 is configured to construct a fourth coefficient linearly amplifying the third equalization coefficient based on the second difference. Preferably, the fourth equalization coefficient may be represented by the following equation:

therein, SOC_dIs the second difference.

Is the second dynamic coefficient. Preferably, the first and second electrodes are formed of a metal,

is the third coefficient. m is₃The value of the fourth coefficient is related to the second difference. m is₃Taking a positive integer, e.g. m in the case of a second difference of 0.4₃The value may be 4.

Preferably, in the case where the supercapacitor pack 201 supplies power to the on-satellite load 40, the equalization parameter may be represented by the following formula:

in the prior art, no matter the average SOC equalization strategy or the active equalization strategy, as the number of the super capacitor banks 201 increases, the equalization efficiency cannot be ensured. In the process of balancing the super capacitor bank 201, the state of charge SOC of the super capacitor bank 201 gradually approaches to be consistent with the continuous balancing of the energy among the super capacitor banks 201. The energy balance is carried out based on the state of charge value SOC of the super capacitor, and the balance is carried out according to the difference of the state of charge value SOC of the super capacitor. If the difference of the soc values of the super capacitors is gradually decreased, the equalizing speed of the energy management module 30 is gradually decreased. Moreover, as the number of the super capacitor banks 201 increases, the number of the super capacitor banks 201 with similar SOC increases, and the balancing speed of the energy management module 30 is greatly reduced. The equalization parameter adopted in the prior art is generally the first equalization coefficient in the present invention, that is, the first equalization coefficient is defined according to the state of charge values between the respective supercapacitor sets 201. The sum of the first equalization coefficients of each supercapacitor bank 201 is generally a constant value of 1, which facilitates control setting of the equalizer 303 and demodulation of the equalization parameters by the current closed loop 302. The second equalization coefficient set by the present invention is a linear superposition of the first equalization coefficients, and the purpose to be achieved is to further amplify the difference between different first equalization coefficients according to the difference of the state of charge values SOC of the super capacitor bank 201, so as to accelerate the equalization speed when the state of charge values of the super capacitor bank 201 tend to be consistent. More importantly, the second equalization coefficient adopted by the invention not only can accelerate the equalization speed, but also is insensitive to the number of the super capacitor sets 201, i.e. the equalization efficiency is not affected as the number of the cascaded super capacitor sets 201 increases. Preferably, the mode that the super capacitor bank 201 supplies power to the on-satellite load 40 is taken as an example to demonstrate that the first equalization coefficient and the second equalization coefficient adopted by the invention are not influenced by the number of the cascaded super capacitor banks 201:

and the balancing speed of the balancing strategy based on the SOC value of the super capacitor is related to a third balancing coefficient. Ideally, when all of the supercapacitor sets 201 are fully equalized, the third equalization coefficient is determined only by the number of the supercapacitor sets 201. Therefore, the third equalization coefficient adjustment amount Δ F of the kth super capacitor group 201 can be obtained_3(k)As shown in the following formula:

wherein, Δ F_3(k)The larger the energy required to be adjusted by the super capacitor bank 201, the faster the equalization speed, and vice versaThe slower the equalization speed, the less energy that needs to be adjusted. The third equalization coefficient adjustment quantity delta F of the (k +1) th super capacitor group 201 can be obtained by the formula_3(k+1)As shown in the following formula:

preferably,. DELTA.F_3(k+1)Minus Δ F_3(k)It is possible to obtain the deviation Δ J of the third equalization coefficient adjustment amount when the number of the supercapacitor groups 201 increases. Δ J may be represented by the following formula:

since the SOC of the supercapacitor set 201 is between 0 and 1, Δ J may be a positive value or a negative value. A positive value indicates that Δ J decreases and the initial equalization speed of the satellite power system decreases. A negative value indicates that Δ J increases and the initial equalization speed of the satellite power system increases. Therefore, under the same condition, Δ J is mainly determined by the SOC of the added super capacitor bank 201, and the fourth equalizing coefficient is also determined by the SOC. In summary, the number of the cascaded super capacitor sets 201 does not affect Δ J, and further does not affect the equalizing speed of the satellite power system. The only effect on the equalization speed is the state of charge value SOC of supercapacitor bank 201.

Preferably, the sum of the second equalization coefficients is zero and the sum of the first equalization coefficients is a constant value of 1, so that the energy management module 30 can strictly track the reference current signal 3022, i.e., the duty cycle generated by the current regulator 3021 in the current closed loop 302 is three parts under the setting of the first equalization coefficients and the second equalization coefficients. Preferably, the first part is the base duty cycle, the duty cycle generated by the reference current signal 3022 generated by the voltage closed loop 301 of the system, around which the duty cycle at which the system actually operates fluctuates. The second part is the duty cycle resulting from the first equalization coefficient with respect to the state of charge value SOC difference. The third part is the duty cycle generated by the second equalization coefficients. Since the sum of the first equalization coefficient is a constant value of 1 and the sum of the second equalization coefficient is zero, the duty ratio of each supercapacitor group 201 varies around the duty ratio of the base value, and the variation is determined by the first equalization coefficient and the second equalization coefficient, but the total average duty ratio of the system is not changed. Therefore, the balance control of each super capacitor group 201 is only related to the duty ratio generated by the first balance coefficient and the second balance coefficient, and the current control of the system is not affected, so that the energy balance among the super capacitor groups 201 can be realized through the control of the first balance coefficient and the second balance coefficient.

In a preferred embodiment, in case the energy generation module 10 charges the energy storage module 20 or the energy storage module 20 supplies the onboard load 40,

energy management module 30 is configured to: the second equalization coefficient and the fourth equalization coefficient are controlled by the equalizer 303 to gradually increase as the second difference decreases. In the case where energy management module 30 is responsive to reference current signal 3022 delivered by voltage closed loop 301, energy management module 30 is configured to: the control equalizer 303 transmits the state of charge SOC of the supercapacitor set 201 to the current closed loop 302 through the dc bus in the form of a dc signal. The current closed loop 302 is configured to: the reference current signal 3022 delivered by the voltage closed loop 301 is re-determined based on the dc signal of the highest state of charge value. Preferably, as shown in FIG. 2, all of the supercapacitor packs 201 share a voltage closed loop 301. The satellite power supply system can be ensured to have the capability of stabilizing the voltage of the power grid through the setting mode. As shown in fig. 2, each supercapacitor pack 201 has an independent current closed loop 302. The reference current signal 3022 and the system current feedback value 3023 are the same within each current closed loop 302. Preferably, as shown in fig. 2, the equalizer 303 delivers the maximum state of charge value into each current closed loop 302 via a dc bus. By the arrangement mode, the super capacitor bank 201 with the low SOC value can perform balance control according to the SOC value thereof. Preferably, the difference between the state of charge value and the maximum state of charge value of the corresponding supercapacitor group 201 is amplified by a proportional element and then transmitted to the current regulator 3021. Preferably, the scaling element 306 is used to proportionally reproduce the change of the input signal without distortion and delay of its output, i.e. without inertia in the transfer of the signal. The scaling element 306 of the present invention is used to communicate the second difference. Through the arrangement mode, the invention has the beneficial effects that:

the equalizer 303 connected to the current closed loop 302 and the dc bus respectively can transmit the maximum SOC value SOC of the super capacitor bank 201 to the current closed loop 302 through the dc bus in the form of a dc signal, so that the maximum SOC value of the dc bus can be directly transmitted to all the super capacitor banks 201, and the current closed loop 302 of each super capacitor bank 201 automatically obtains a second difference value in the second equalization coefficient. The state of charge value SOC of the super capacitor bank 201 is directly transmitted in a direct current signal mode by using a direct current bus instead of a communication line, so that the information amount processed by the equalizer 303 is further simplified, and the key parameter state of charge value SOC used for determining equalization control is lowered into the current closed loop 302 corresponding to each super capacitor bank 201 through the direct current bus, so that the state of charge value SOC is not required to be processed by the equalizer 303 in a centralized manner, and the equalization capability of the energy management module 30 is not influenced after any super capacitor bank 201 is stopped due to faults. And because the direct current carrier transmits signals of the state of charge (SOC), and the sum of the signals is a fixed value, the anti-interference capability of the direct current signals can be further improved by utilizing the proportional amplifier.

Preferably, the equalizer 303 is further configured to generate a current compensation parameter based on the second difference and introduce the current compensation parameter into the current closed loop 302 in the form of a direct current signal. In the process of using the form of the direct current signal to transmit the state of charge value SOC, a problem of large deviation of the current output by the satellite power supply system may be caused. The use of a dc signal to convey the state of charge value and the use of a second equalization coefficient can amplify the duty cycle between different supercapacitor groups 201, which, although the increased difference in duty cycle facilitates the energy equalization between supercapacitor groups 201, also leads to the problem of larger deviations in system current. In order to reduce the influence of the energy management module 30 on the output current generated by the equalization control of the energy storage module 20, the output current needs to be adjusted, that is, a current compensation parameter generated based on the second difference value is introduced into the current closed loop 302 to compensate the reference current signal 3022 generated by the voltage closed loop 301, so that the service life of the super capacitor can be prolonged. Through the arrangement mode, in the process that the satellite power supply system uses the energy storage module 20 only composed of the super capacitors to perform multi-closed-loop energy balance control, the reference current signal 3022 required by the current closed loop 302 is transmitted through the direct current bus in the voltage closed loop 301, the communication data volume and the processing cost are greatly reduced in a mode of simulating current transmission information, and the balance speed is accelerated by further amplifying the difference of the second balance coefficient to the charge state value of the super capacitor group 201. Moreover, the sum of the second equalization coefficients is zero, and the sum of the first equalization coefficients is a fixed value 1, so that the energy management module 30 can strictly track the current reference signal, and as the number of the super capacitor banks 201 increases, the equalization speed based on the state of charge value is also related to the number of the super capacitor banks 201, but the first equalization coefficients and the second equalization coefficients are mainly determined by the state of charge value SOC, which indicates that the number of the cascaded super capacitor banks 201 does not affect the equalization speed of the energy management module 30, and the only effect on the equalization speed of the energy management module 30 is the state of charge value of the super capacitor banks 201, so that the equalization efficiency of the energy management module 30 can still be ensured under the condition that the number of the super capacitor banks 201 increases through the setting of the second equalization coefficients.

Preferably, the equalizer 303 in this embodiment may be an editable logic Gate Array (FPGA), such as an antifuse FPGA. It can also be an irradiation-resistant FPGA or a Complex Programmable Logic Device (CPLD).

Preferably, the energy management module 30 further comprises a storage unit. The Memory unit may be a Static Random-Access Memory (SRAM).

Example 2

This embodiment is a further supplement to embodiment 1, and repeated content is not described again.

The embodiment also provides a configuration method of the modular satellite power supply system, which comprises the following steps:

the energy storage module 20 of at least one super capacitor bank 201 composed of a plurality of super capacitors stores the electric energy generated by the energy generation module 10 and supplies the electric energy to the on-board load 40 based on the control of the energy management module 30, and the super capacitor bank 201 serves as a unique energy storage device for storing the whole electric energy generated by the energy generation module 10 and a unique energy supply device for supplying the electric energy to the on-board load 40 in at least two ways of changing the voltage value in response to the control of the energy management module 30.

Preferably, as shown in fig. 6, the energy management module 30 performs the following steps:

s100: the voltage value 3013 based on the dc bus feedback and the reference voltage signal 3012 output a reference current signal 3022 through the voltage closed loop 301. Preferably, the voltage closed loop 301 transmits signals in the form of direct current through a direct current bus. The voltage closed loop 301 is a voltage closed loop 301 shared by all the supercapacitor sets 201, as shown in fig. 2. The current closed loop 302 is within the voltage closed loop 301. The current closed loop 302 forms a closed loop with each super capacitor bank 201. The equalizer 303 is connected to the current closed loop 302 and the dc bus. The present embodiment replaces the communication line in the prior art by the connection with the dc bus by the shared voltage closed loop 301 based on a certain simplification of the structure and reduction of the energy loss. Since the common voltage closed loop 301 is connected with the dc bus and transmits the state of charge value of the super capacitor bank 201 and the reference current signal 3022 generated by the voltage closed loop 301 by using the dc signal, the system can be ensured to have the capability of stabilizing the satellite power system. The traditional multi-closed-loop control system transmits voltage signals or current signals by using a communication line, because a direct current bus is used for transmitting signals, and the carrier or information quantity of the signals is the amplitude of direct current, the direct current bus generates voltage drop, the voltage drop is easy to change along with the length of the direct current bus, and the transmission of the direct current signals is limited, so that the traditional multi-closed-loop control system transmits information by using digital signals. However, the adoption of digital signals requires additional communication lines for equalization to transmit the digital signals, the increase of the number of the super capacitor banks 201 inevitably leads to the complication of the whole satellite communication line, and the generation of huge communication data by the digital signals also brings computational burden to the processor. The reference current signal 3022 required by the current closed loop 302 is transmitted through the direct current bus in the voltage closed loop 301, so that the communication data volume and the processing cost can be greatly reduced in a mode of simulating current transmission information, and the problem of low anti-interference capability caused by transmission loss can be greatly reduced due to the short length of the direct current bus of the satellite power supply system, so that the complexity of lines and huge data information can be avoided under the condition of sacrificing part of anti-interference capability.

Preferably, the energy management module 30 is configured to output a reference current signal 3022 through the voltage closed loop 301 based on the voltage value 3013 fed back by the dc bus and the reference voltage signal 3012.

S200: the equalizer 303 is adjusted to output the equalization parameters of each supercapacitor bank 201 in response to the difference between the reference current signal 3022 and the system current feedback value 3023. Preferably, in case the energy generation module 10 charges the energy storage module 20, the equalizer 303 performs the following steps:

the state of charge value of each supercapacitor set 201 is obtained in an online estimation mode based on the voltage value and the current value fed back by the voltage closed loop 301 and the current closed loop 302, so that an equalization parameter which at least comprises a first equalization coefficient and a second equalization coefficient and is always kept at a constant value in sum is constructed.

Preferably, in the case that the energy generation module 10 charges the energy storage module 20, the first equalization coefficient is a ratio of the first difference value of the corresponding super capacitor bank 201 to the sum of the first difference values of all super capacitor banks 201. The sum of the first equalization coefficients of all the supercapacitor sets 201 is a constant value. The constant value may be 1. The first difference is defined by the difference between the state of charge value and the fixed value of the respective supercapacitor pack 201. Preferably, the first equalizing coefficient F₁Can be represented by the following formula:

wherein, 1-SOC_iIs the first difference.

therein, SOC_dIs the second difference.

Is the first dynamic coefficient.

Is the first coefficient. m is₁The value of the second coefficient is related to the second difference. m is₁Taking a positive integer, e.g. m in the case of a second difference of 0.4₁The value may be 4. m is₂For the gain factor, it is generally takenThe value is 2.

preferably, in the case that the energy storage module 20 supplies power to the on-satellite load 40, the equalizer 303 constructs an equalization parameter based on the acquired state of charge value of each super capacitor bank 201. The equalization parameters include at least a third equalization coefficient and a fourth equalization coefficient. The sum of the equalization parameters of each supercapacitor group 201 is always kept constant. Preferably, the third equalization coefficient is configured as a ratio of the state of charge value of the corresponding supercapacitor group 201 to the sum of the state of charge values of all supercapacitor groups 201. The sum of the third equalization coefficients of all the super capacitor sets 201 is a constant value. The third equalization coefficient may be represented by:

therein, SOC_dIs the second difference.

preferably, in the prior art, no matter the average SOC balancing strategy or the active balancing strategy, as the number of the super capacitor banks 201 increases, the balancing efficiency cannot be guaranteed. In the process of balancing the super capacitor bank 201, the state of charge SOC of the super capacitor bank 201 gradually approaches to be consistent with the continuous balancing of the energy among the super capacitor banks 201. The energy balance is carried out based on the state of charge value SOC of the super capacitor, and the balance is carried out according to the difference of the state of charge value SOC of the super capacitor. If the difference of the soc values of the super capacitors is gradually decreased, the equalizing speed of the energy management module 30 is gradually decreased. Moreover, as the number of the super capacitor banks 201 increases, the number of the super capacitor banks 201 with similar SOC increases, and the balancing speed of the energy management module 30 is greatly reduced. The equalization parameter adopted in the prior art is generally the first equalization coefficient in the present invention, that is, the first equalization coefficient is defined according to the state of charge values between the respective supercapacitor sets 201. The sum of the first equalization coefficients of each supercapacitor bank 201 is generally a constant value of 1, which facilitates control setting of the equalizer 303 and demodulation of the equalization parameters by the current closed loop 302. The second equalization coefficient set by the present invention is a linear superposition of the first equalization coefficients, and the purpose to be achieved is to further amplify the difference between different first equalization coefficients according to the difference of the state of charge values SOC of the super capacitor bank 201, so as to accelerate the equalization speed when the state of charge values of the super capacitor bank 201 tend to be consistent. More importantly, the second equalization coefficient adopted by the invention not only can accelerate the equalization speed, but also is insensitive to the number of the super capacitor sets 201, i.e. the equalization efficiency is not affected as the number of the cascaded super capacitor sets 201 increases. Preferably, the mode that the super capacitor bank 201 supplies power to the on-satellite load 40 is taken as an example to demonstrate that the first equalization coefficient and the second equalization coefficient adopted by the invention are not influenced by the number of the cascaded super capacitor banks 201:

wherein, Δ F_3(k)A larger value indicates that the more energy the supercapacitor set 201 needs to be tuned, the faster the balancing speed, whereas if the less energy needs to be tuned, the slower the balancing speed. The third equalization coefficient adjustment quantity delta F of the (k +1) th super capacitor group 201 can be obtained by the formula_3(k+1) As shown in the following formula:

preferably,. DELTA.F_3(k+1)Minus Δ F_3(k)It can be obtained that when the number of the super capacitor sets 201 increases, the third equalization coefficient adjustment amountDeviation Δ J of (a). Δ J may be represented by the following formula:

Preferably, as shown in FIG. 2, all of the supercapacitor packs 201 share a voltage closed loop 301. The satellite power supply system can be ensured to have the capability of stabilizing the voltage of the power grid through the setting mode. As shown in fig. 2, each supercapacitor pack 201 has an independent current closed loop 302. The reference current signal 3022 and the system current feedback value 3023 are the same within each current closed loop 302. Preferably, as shown in fig. 2, the equalizer 303 delivers the maximum state of charge value into each current closed loop 302 via a dc bus. By the arrangement mode, the super capacitor bank 201 with the low SOC value can perform balance control according to the SOC value thereof. Preferably, the difference between the state of charge value and the maximum state of charge value of the corresponding supercapacitor group 201 is amplified by a proportional element and then transmitted to the current regulator 3021. Preferably, the scaling element 306 is used to proportionally reproduce the change of the input signal without distortion and delay of its output, i.e. without inertia in the transfer of the signal. The scaling element 306 of the present invention is used to communicate the second difference. Preferably, the equalizers 303 connected to the current closed loop 302 and the dc bus respectively are capable of transferring the maximum SOC value SOC of the supercapacitor groups 201 into the current closed loop 302 through the dc bus in the form of a dc signal, so that the maximum SOC value of all the supercapacitor groups 201 can be directly transferred in the dc bus, and the current closed loop 302 of each supercapacitor group 201 automatically obtains the second difference value in the second equalization coefficient. The state of charge value SOC of the super capacitor bank 201 is directly transmitted in a direct current signal mode by using a direct current bus instead of a communication line, so that the information amount processed by the equalizer 303 is further simplified, and the key parameter state of charge value SOC used for determining equalization control is lowered into the current closed loop 302 corresponding to each super capacitor bank 201 through the direct current bus, so that the state of charge value SOC is not required to be processed by the equalizer 303 in a centralized manner, and the equalization capability of the energy management module 30 is not influenced after any super capacitor bank 201 is stopped due to faults. And because the direct current carrier transmits signals of the state of charge (SOC), and the sum of the signals is a fixed value, the anti-interference capability of the direct current signals can be further improved by utilizing the proportional amplifier.

Preferably, the equalizer 303 generates a current compensation parameter based on the second difference and introduces the current compensation parameter into the current closed loop 302 in the form of a direct current signal. In the process of using the form of the direct current signal to transmit the state of charge value SOC, a problem of large deviation of the current output by the satellite power supply system may be caused. The use of a dc signal to convey the state of charge value and the use of a second equalization coefficient can amplify the duty cycle between different supercapacitor groups 201, which, although the increased difference in duty cycle facilitates the energy equalization between supercapacitor groups 201, also leads to the problem of larger deviations in system current. In order to reduce the influence of the energy management module 30 on the output current generated by the equalization control of the energy storage module 20, the output current needs to be adjusted, that is, a current compensation parameter generated based on the second difference value is introduced into the current closed loop 302 to compensate the reference current signal 3022 generated by the voltage closed loop 301, so that the service life of the super capacitor can be prolonged.

S300: and generating a driving signal for equalizing and charging the super capacitor bank 201 through the current closed loop 302 based on the equalization parameter. Preferably, during the process of realizing energy balance of the super capacitor bank 201 in the energy storage module 20, the problem of overcharge or overdischarge of the super capacitor bank 201 is easily caused. The present embodiment utilizes the voltage fed back by the dc bus and the reference voltage signal 3012 set based on the number and specification of the super capacitor sets 201 to input into the voltage closed loop 301. A voltage regulator 3011 within the voltage closed loop 301 generates a reference current signal 3022. The difference generated by reference current signal 3022 and system current feedback value 3023 is combined with the equalization parameters generated by equalizer 303 for each supercapacitor bank 201 and the result is fed into current closed loop 302 of each supercapacitor bank 201. Current regulator 3021 within current closed loop 302 generates a duty cycle of ultracapacitor bank 201 based on the input results, the duty cycle being proportional to state of charge value SOC of ultracapacitor bank 201, and thus energy balance of each ultracapacitor bank 201 can be controlled by the duty cycle.

Preferably, in the case that the equalizer 303 performs equalization control based on the duty ratio generated by the current closed loop 302, in the case that the energy generation module 10 charges the energy storage module 20, the equalizer 303 controls the super capacitor bank 201 with a low state of charge value to be charged with a duty ratio larger than that of the super capacitor bank 201 with a high state of charge value. Preferably, a supercapacitor pack 201 with a low state of charge value refers to a supercapacitor pack 201 with a lower state of charge value. And under the condition that the energy storage module 20 supplies power to the on-board load 40, controlling the super capacitor bank 201 with the low charge state value to discharge at a duty ratio smaller than that of the super capacitor bank 201 with the high charge state value. And controlling the current closed loop 302 to charge or discharge the super capacitor bank 201 at the same duty ratio under the condition that the state of charge values of all the super capacitor banks 201 are consistent.

The word "module" as used herein describes any type of hardware, software, or combination of hardware and software that is capable of performing the functions associated with the "module".

It should be noted that the above-mentioned embodiments are exemplary, and that those skilled in the art, having benefit of the present disclosure, may devise various arrangements that are within the scope of the present disclosure and that fall within the scope of the invention. It should be understood by those skilled in the art that the present specification and figures are illustrative only and are not limiting upon the claims. The scope of the invention is defined by the claims and their equivalents.

Claims

1. A satellite power supply system comprises at least an energy management module (30),

it is characterized in that the preparation method is characterized in that,

the energy storage module (20) comprises at least one unique energy storage device configured to store all electric energy generated by the energy generation module (10) and a super capacitor bank (201) of the unique energy supply device which supplies power to the on-board load (40) in a manner of at least two changes of voltage value in response to the control of the energy management module (30), wherein the maximum state of charge (SOC) value of the super capacitor bank (201) is transferred into the current closed loop (302) through an equalizer (303) connected with the current closed loop (302) and a direct current bus in the form of a direct current signal through the direct current bus, so that the maximum value of the state of charge value is directly transferred to all the super capacitor banks (201) in the direct current bus, and the current closed loop (302) of each super capacitor bank (201) automatically acquires a second difference value in a second equalization coefficient.

2. The satellite power supply system according to claim 1, wherein the second equalization coefficient is a linear superposition of first equalization coefficients configured as a ratio of the first difference of the respective supercapacitor group (201) to the sum of the first differences of all supercapacitor groups (201) to further amplify the difference between different first equalization coefficients according to the difference in state of charge values SOC of the supercapacitor groups (201).

3. Satellite power supply system according to claim 2, characterized in that the second equalization coefficient F₂Can be represented by the following formula:

therein, SOC_dIn order to be the second difference value,

is a first dynamic coefficient of the image data,

is the first coefficient, m₁For the second coefficient, the value is related to the second difference, m₁Taking a positive integer, e.g. m in the case of a second difference of 0.4₁Can take the value of 4, m₂The gain factor is typically 2.

4. Satellite power supply system according to claim 3, characterized in that the second equalization coefficients comprise at least a second difference defined by the difference between the maximum and minimum values of the state of charge values of all the supercapacitor groups (201) and a first dynamic coefficient for defining the second difference such that the sum of the second equalization coefficients of all the supercapacitor groups (201) remains zero.

5. The satellite power supply system according to claim 4, wherein the first dynamic coefficient includes at least a first coefficient and a second coefficient proportional to the second difference, wherein,

constructing a first coefficient whose sum remains zero based on the difference between the average of the first differences of the supercapacitor group (201) and the first difference of the corresponding supercapacitor group (201);

constructing a second coefficient that linearly amplifies the second equalization coefficient based on the second difference.

6. The satellite power supply system according to claim 5, wherein the energy management module (30) is capable of being connected with the energy storage module (20) through a bidirectional DC-DC converter, and in the case that the energy storage module (20) supplies power to the on-board load (40), the equalizer (303) constructs an equalization parameter based on the acquired state-of-charge value of each super capacitor bank (201), wherein the equalization parameter comprises at least a third equalization coefficient and a fourth equalization coefficient.

7. The satellite power supply system according to claim 6, wherein the energy management module (30) is configured to control the second equalization coefficient and the fourth equalization coefficient to gradually increase with a decrease in the second difference through the equalizer (303).

8. The satellite power supply system according to claim 7, wherein all of the super capacitor banks (201) share a voltage closed loop (301) to ensure the satellite power supply system has the capability of stabilizing the grid voltage.

9. The satellite power supply system according to claim 8, wherein the equalizer (303) is further configured to generate a current compensation parameter based on the second difference and introduce the current compensation parameter into the current closed loop (302) in the form of a direct current signal.

10. The satellite power supply system according to claim 9, wherein the calculation method of the SOC of the super capacitor at least includes reflecting the current storage capacity of the super capacitor from different angles based on two forms of charge and power.