CN116014917A - Wireless energy supply system, closed-loop control method thereof and maximum power tracking method - Google Patents

Wireless energy supply system, closed-loop control method thereof and maximum power tracking method Download PDF

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CN116014917A
CN116014917A CN202310282287.0A CN202310282287A CN116014917A CN 116014917 A CN116014917 A CN 116014917A CN 202310282287 A CN202310282287 A CN 202310282287A CN 116014917 A CN116014917 A CN 116014917A
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converter
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CN116014917B (en
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蔡榕
熊振阳
徐国宁
李永祥
杜浩
贾忠臻
李兆杰
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Aerospace Information Research Institute of CAS
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    • Y02E10/56Power conversion systems, e.g. maximum power point trackers

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Abstract

The invention provides a wireless energy supply system, a closed-loop control method thereof and a maximum power tracking method thereof, and belongs to the technical field of wireless energy transmission. The wireless energy supply system comprises: a photovoltaic array, a DC-DC converter and an energy storage battery; the closed-loop control method comprises the following steps: by monitoring the output voltage of the photovoltaic array in real time, the working modes of the wireless energy supply system are determined according to the state conditions met by the real-time output voltage, the real-time output current and the real-time state of charge of the energy storage battery of the DC-DC converter, wherein the working modes comprise a maximum power tracking mode, a constant current output mode and a constant voltage output mode. The invention supports the self-adaptive switching of the system working mode, so that the wireless energy supply system can meet the maximum output power, and meanwhile, the overload phenomenon of the energy storage battery is avoided, the safe and stable operation of the whole system is ensured, the energy utilization efficiency of the photovoltaic array is improved, and the service life of the energy storage battery is prolonged.

Description

Wireless energy supply system, closed-loop control method thereof and maximum power tracking method
Technical Field
The invention relates to the technical field of wireless energy transmission, in particular to a wireless energy supply system, a closed-loop control method thereof and a maximum power tracking method thereof.
Background
The laser wireless energy supply technology is to use laser as an energy carrier to realize wireless energy transmission, convert the electric energy of a power supply system into laser energy, accurately transmit the laser energy to a photovoltaic array, convert the laser energy into electric energy for storage, and provide energy for an engine or complete other tasks. The laser has strong directivity and concentrated energy, can carry a large amount of energy, is higher than the photoelectric conversion efficiency of a solar battery as a long-distance transmission means and has high output power, and can provide 24 hours uninterrupted power for an energy supply object, thereby being widely applied to the energy supply of an aerostat which can not directly supply power from the ground through a transmission cable.
In practical application, the current laser wireless energy supply system is limited by a laser emission principle, laser intensity is unevenly distributed in a cross section, so that the laser illumination intensity received by each single photovoltaic cell in a photovoltaic array formed in a serial-parallel connection mode is different, and then current generated among the single photovoltaic cells is not matched, finally, a P-U (output power-output voltage) characteristic curve output by the photovoltaic array is multimodal, and the maximum power output of the photovoltaic array in the laser wireless energy supply system is realized by adopting a DC-DC converter and a maximum power tracking control algorithm according to the characteristic of the laser wireless energy supply system according to the real-time dynamic change of illumination intensity and the temperature of the photovoltaic cell.
However, the existing maximum power tracking control algorithm is easy to fall into local optimum, so that the maximum power tracking is difficult, and the maximum output capacity of the photovoltaic array is difficult to realize. In addition, the output of the laser wireless energy supply system is difficult to maintain stable under the influence of illumination intensity, photovoltaic cell temperature change and load change, and the robustness and dynamic performance of the system under large signal disturbance are difficult to ensure by the traditional linear closed-loop control method. It can be seen that it is also difficult for existing laser wireless power supply systems to guarantee a stable and optimal power output capability.
Disclosure of Invention
Aiming at the problems existing in the prior art, the embodiment of the invention provides a wireless energy supply system, a closed-loop control method thereof and a maximum power tracking method.
The invention provides a wireless energy supply system, comprising: a photovoltaic array, a DC-DC converter, and an energy storage battery; the photovoltaic array is connected with the energy storage battery through the DC-DC converter; the DC-DC converter comprises a main control chip; wherein,,
the main control chip is used for monitoring the real-time output voltage and the real-time output current of the DC-DC converter and the real-time charge state of the energy storage battery;
the main control chip is also used for determining the working mode of the wireless energy supply system according to the real-time output voltage and the real-time output current of the DC-DC converter and the state conditions met by the real-time state of charge of the energy storage battery.
According to the wireless energy supply system provided by the invention, the main control chip comprises a maximum power tracking mode control loop; the working modes comprise a maximum power tracking mode;
the maximum power tracking mode control loop is further configured to determine that the working mode of the wireless energy supply system is the maximum power tracking mode when the real-time state of charge of the energy storage battery is not in a full state and the real-time output current of the DC-DC converter is not higher than the safe charging current of the energy storage battery;
the maximum power tracking mode includes: and adjusting the duty ratio of the DC-DC converter to change the output power of the photovoltaic array until the output power of the photovoltaic array reaches the maximum power in the current state.
According to the wireless energy supply system provided by the invention, the main control chip comprises a constant voltage output mode control loop; the working mode comprises a constant voltage output mode;
the constant voltage output mode control loop is used for switching the working mode into the constant voltage output mode when the real-time state of charge of the energy storage battery is in a full state;
the constant voltage output mode includes: and adjusting the output voltage of the DC-DC converter so that the output voltage of the DC-DC converter is the same as the full-charge voltage of the energy storage battery.
According to the wireless energy supply system provided by the invention, the main control chip comprises a constant current output mode control loop, and the working mode comprises a constant current output mode;
the constant current output mode control loop is used for switching the working mode of the wireless energy supply system into the constant current output mode when the real-time charge state of the energy storage battery is not in a full charge state and the real-time output current of the DC-DC converter is higher than the safe charging current of the energy storage battery; the constant current output mode includes: the duty cycle of the DC-DC converter is adjusted such that the output current of the DC-DC converter is the same as the safe charging current of the energy storage battery.
According to the wireless energy supply system provided by the invention, the system further comprises a laser transmitting end; wherein,,
the laser emission end is used for emitting laser to the photovoltaic array so that the photovoltaic array converts laser energy into first voltage and outputs the first voltage to the DC-DC converter;
the DC-DC converter is used for converting the first voltage into a second voltage so as to enable the energy storage battery to store electric energy.
The invention also provides a closed-loop control method which is applied to the wireless energy supply system according to any one of the above; comprising the following steps:
Monitoring a real-time output voltage, a real-time output current of the DC-DC converter and a real-time state of charge of the energy storage battery;
and determining the working mode of the wireless energy supply system according to the state conditions met by the real-time output voltage, the real-time output current and the real-time state of charge of the energy storage battery of the DC-DC converter.
According to the closed-loop control method provided by the invention, the working mode of the wireless energy supply system is determined according to the state conditions met by the real-time output voltage, the real-time output current and the real-time state of charge of the energy storage battery of the DC-DC converter, and the method comprises the following steps:
when the real-time state of charge of the energy storage battery is not in a full-charge state and the real-time output current of the DC-DC converter is not higher than the safe charging current of the energy storage battery, determining that the working mode of the wireless energy supply system is a maximum power tracking mode; the maximum power tracking mode includes: and adjusting the duty ratio of the DC-DC converter to change the output power of the photovoltaic array until the output power of the photovoltaic array reaches the maximum output power in the current state.
According to the closed-loop control method provided by the invention, the working mode of the wireless energy supply system is determined according to the state conditions met by the real-time output voltage, the real-time output current and the real-time state of charge of the energy storage battery of the DC-DC converter, and the method comprises the following steps:
When the real-time state of charge of the energy storage battery is in a full-charge state, switching the working mode of the wireless energy supply system into a constant-voltage output mode; the constant voltage output mode includes: the duty cycle of the DC-DC converter is adjusted so that the output voltage of the DC-DC converter is the same as the full charge voltage of the energy storage battery.
According to the maximum power tracking method provided by the invention, the working mode of the wireless energy supply system is determined according to the state conditions met by the real-time output voltage, the real-time output current and the real-time state of charge of the energy storage battery of the DC-DC converter, and the method comprises the following steps:
when the real-time charge state of the energy storage battery is not in a full-charge state and the real-time output current of the DC-DC converter is higher than the safe charging current of the energy storage battery, switching the working mode of the wireless energy supply system into a constant-current output mode; the constant current output mode includes: the duty cycle of the DC-DC converter is adjusted so that the output current of the DC-DC converter is the same as the safe charging current of the energy storage battery.
The invention also provides a maximum power tracking method which is applied to the wireless energy supply system and comprises the following steps:
Monitoring a real-time output voltage, a real-time output current of the DC-DC converter and a real-time state of charge of the energy storage battery;
when the real-time state of charge of the energy storage battery is not in a full-charge state and the real-time output current of the DC-DC converter is not higher than the safe charging current of the energy storage battery, determining that the working mode of the wireless energy supply system is a maximum power tracking mode; the maximum power tracking mode includes: and adjusting the duty ratio of the DC-DC converter to change the output power of the photovoltaic array until the output power of the photovoltaic array reaches the maximum output power in the current environment state.
According to the maximum power tracking method provided by the invention, the maximum power tracking mode further comprises the following steps:
taking the duty ratio of the DC-DC converter as a position variable of particles in a particle swarm, and iteratively updating the position variable of the particles by using a particle swarm optimization algorithm based on predation search strategy to obtain a global optimal position of the particle swarm;
and calculating the output voltage of the photovoltaic array based on the global optimal position, and obtaining the maximum output power of the wireless energy supply system corresponding to the output voltage in the current environment state.
According to the maximum power tracking method provided by the invention, the maximum power tracking mode further comprises the following steps:
determining a global search space of a duty ratio of a DC-DC converter, and dividing the global search space into a plurality of subspaces with different levels;
determining a subspace of a current level to be searched;
initializing the particle swarm scale and the maximum iteration number in the subspace of the current level;
performing iterative optimization in the subspace of the current level, and updating a local optimal solution according to a preset fitness function until a better solution is obtained within a preset maximum iteration number;
taking the better solution as a historical optimal solution, and updating the level according to the level relation to obtain an updated subspace of the current level; and returning to the step of determining the subspace of the current level to be searched.
The maximum power tracking method provided by the invention further comprises the following steps: if no better solution exists in the preset maximum iteration times, updating the level according to the level relation, obtaining an updated subspace of the current level, returning to the subspace of the current level to be searched, until the updated level reaches the preset level, and outputting the current obtained historical optimal solution;
And taking the currently obtained historical optimal solution as a global optimal solution in the global search space.
According to the maximum power tracking method provided by the invention, after monitoring the real-time output voltage, the real-time output current and the real-time state of charge of the energy storage battery of the DC-DC converter, the method further comprises:
and after the real-time output voltage and the real-time output current of the DC-DC converter and the real-time charge state of the energy storage battery are subjected to weighted comparison by using a preset weight function, judging the state condition met by the photovoltaic array wireless energy supply system according to the comparison result.
The invention also provides an electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements any one of the closed-loop control methods or any one of the maximum power tracking methods when executing the program.
The present invention also provides a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements any of the closed loop control methods described above, or any of the maximum power tracking methods described above.
The invention also provides a computer program product comprising a computer program which when executed by a processor implements any of the closed loop control methods described above, or any of the maximum power tracking methods described above.
According to the wireless energy supply system and the maximum power tracking method, the output voltage of the photovoltaic array is monitored in real time, and the working mode of the wireless energy supply system is determined according to the real-time output voltage, the real-time output current of the DC-DC converter and the state conditions met by the real-time state of charge of the energy storage battery, so that the working mode of the wireless energy supply system can be flexibly switched, the photovoltaic array can work near the maximum output power point, the safe work of the energy storage battery is ensured, the energy utilization efficiency of the photovoltaic array is improved, and the service life of the energy storage battery is prolonged.
Drawings
In order to more clearly illustrate the invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a wireless power supply system according to the present invention;
FIG. 2 is a schematic flow chart of a closed loop control method provided by the present invention;
FIG. 3 (a) is a schematic illustration of the I-V curve of a photovoltaic cell;
FIG. 3 (b) is a schematic illustration of the P-U curve of a photovoltaic cell;
FIG. 4 is a schematic flow chart of a maximum power tracking method according to the present invention;
FIG. 5 is a second flowchart of a maximum power tracking method according to the present invention;
FIG. 6 is a schematic diagram of a global search space and its subspaces;
FIG. 7 is a third flow chart of the maximum power tracking method according to the present invention;
FIG. 8 is a schematic diagram of a linear weight compensator in a wireless power supply system according to the present invention;
FIG. 9 is a schematic diagram of a photovoltaic array in a wireless power supply system according to one embodiment;
FIG. 10 is a schematic circuit diagram of a wireless power supply system in one embodiment;
FIG. 11 is a schematic diagram of the operation result of the maximum power tracking method provided by the invention;
FIG. 12 (a) is a schematic diagram showing the power variation of the operation result of the maximum power tracking method according to the present invention;
FIG. 12 (b) is a schematic diagram of the current variation of the operation result of the maximum power tracking method according to the present invention;
FIG. 12 (c) is a voltage variation diagram of the maximum power tracking method according to the present invention;
fig. 13 is a schematic structural diagram of an electronic device provided by the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Specific embodiments of the present invention are described below in conjunction with fig. 1-13.
As shown in fig. 1, fig. 1 shows a schematic diagram of a wireless power supply system in the present invention; the wireless energy supply system comprises a photovoltaic array, a DC-DC converter (Direct Current-Direct Current Converter; direct Current-Direct Current converter) and an energy storage battery; the photovoltaic array is connected with the energy storage battery through a DC-DC converter, and the DC-DC converter is used for converting unstable low-voltage direct current output by the photovoltaic array into stable bus voltage and simultaneously tracking the maximum output power of the photovoltaic array. The DC-DC converter comprises a main control chip, wherein the circuit structure of the main control chip mainly comprises a maximum power tracking mode control loop, a constant voltage output mode control loop, a constant current output mode control loop, a control mode decision module and a PWM (Pulse Width Modulation, PWM, pulse width modulation) module; each control loop can monitor input and output signals of the DC-DC converter, and calculate a difference e between output voltage of the photovoltaic array and reference voltage by using each comparison link, so that switching of the wireless energy supply system in different working modes is realized by each self-adaptive closed-loop controller, or when disturbance occurs, the duty ratio of the DC-DC converter is regulated by the PWM module, and tracking of maximum output power of the photovoltaic array and stable control of the system are realized.
In an embodiment, the main control chip is configured to monitor a real-time output voltage, a real-time output current of the DC-DC converter, and a real-time state of charge of the energy storage battery.
The DC-DC converter is used for converting direct current voltage output by the photovoltaic array into direct current voltage which can be used by an energy storage battery or a load; the main working mode is a pulse width modulation (Pulse Width Modulation, PWM, pulse width modulation) working mode, and the basic principle is that direct current is chopped into square waves (pulse waves) through a switching tube, and the duty ratio (the ratio of pulse width to pulse period) of the square waves is adjusted through a PWM module to change the voltage. Alternatively, the DC-DC converter may be a buck converter or a boost converter. An energy storage battery, also called a storage battery, is used to reflect the ratio of the remaining capacity of the battery to the full capacity of the battery.
Specifically, the main control chip samples the input and output signals of the DC-DC converter to obtain the real-time output voltage of the DC-DC converter
Figure SMS_1
Real-time output current->
Figure SMS_2
The main control chip can also acquire the real-time state of charge (SOC) of the energy storage battery through sampling.
The main control chip is also used for determining the working mode of the wireless energy supply system according to the state conditions met by the real-time output voltage, the real-time output current and the real-time state of charge of the energy storage battery of the DC-DC converter.
Specifically, in order to realize that the photovoltaic array always works near the maximum output power point, whether the current wireless energy supply system works near the maximum output power point of the photovoltaic array is judged through real-time output voltage and real-time output current of the DC-DC converter which are monitored in real time, if the photovoltaic array does not work near the maximum output power point, the duty ratio of the DC-DC converter is regulated through the maximum power tracking mode control loop until the output power of the photovoltaic array reaches the maximum output power point under the current environmental condition.
In addition, because the wireless energy supply system comprises a photovoltaic array and an energy storage battery, the working state of the energy storage battery is also easy to change due to the change of the environment (such as the temperature of the energy storage battery), and the output voltage or the output current of the photovoltaic array can exceed the safe working current or the full-charge voltage of the energy storage battery and possibly cause the instability of the system; specifically, the main control chip can collect the real-time output voltage, the real-time output current and the real-time charge state of the energy storage battery of the DC-DC converter through the constant-voltage output mode control loop or the constant-current output mode control loop, and judge the difference value between the real-time sampling value and the reference value through respective comparison links, so as to judge the current required working mode of the wireless energy supply system, and switch the wireless energy supply system to the constant-voltage output mode or the constant-current output mode through the trigger control mode decision module.
According to the embodiment, the physical quantity in the wireless energy supply system is monitored in real time through the main control chip in the DC-DC converter, the state conditions met by the wireless energy supply system are judged through the relation among the physical quantities, and the working mode of the wireless energy supply system is adaptively adjusted according to the state conditions, so that the wireless energy supply system can ensure safe and stable operation of the wireless energy supply system while meeting the maximum power output, the energy efficient conversion and utilization of the whole wireless energy supply system are ensured, and the stability and reliability of the whole system are improved.
In an embodiment, the master control chip includes a maximum power tracking mode control loop; the operation mode includes a maximum power tracking mode.
The control loop of the maximum power tracking mode is further configured to determine that the working mode of the wireless energy supply system is the maximum power tracking mode when the real-time state of charge of the energy storage battery is not in the full state and the real-time output current of the DC-DC converter is not higher than the safe charging current of the energy storage battery; the maximum power tracking mode includes: and adjusting the duty ratio of the DC-DC converter to change the equivalent load of the photovoltaic array until the output power of the photovoltaic array reaches the maximum power in the current state.
Specifically, as shown in FIG. 1, the maximum power tracking mode control loop includes an input voltage for the DC-DC converter
Figure SMS_4
Input current->
Figure SMS_7
MPPT controller (maximum power tracking controller), comparison link, self-adaptive closed-loop controller +.>
Figure SMS_9
. Wherein the input voltage->
Figure SMS_5
Input current->
Figure SMS_8
The input voltage and the input current of the DC-DC converter are input voltage and input current of the photovoltaic array; MPPT controller is used for given maximum power point's reference voltage +.>
Figure SMS_10
The comparison step calculates the output voltage of the photovoltaic array by comparison>
Figure SMS_11
Reference voltage +.>
Figure SMS_3
The difference e between them, and thus via an adaptive closed-loop controller +.>
Figure SMS_6
And triggering a control mode decision module to switch the working mode of the wireless energy supply system into a maximum power tracking mode according to the judgment result of the difference e, and realizing maximum output power tracking of the photovoltaic array through the adjustment of the duty ratio of the DC-DC converter by the PWM module in the maximum power tracking mode.
Further, global maximum power tracking of the photovoltaic array output multimodal power curve may be achieved by an MPPT (Maximum Power Point Tracking ) algorithm.
Furthermore, the MPPT algorithm can be realized by a particle swarm optimization algorithm (predator Search-Particle Swarm Optimization; PS-PSO) based on predation Search strategy.
According to the embodiment, the output voltage of the photovoltaic array is monitored in real time, so that the output voltage of the photovoltaic array can be regulated, the photovoltaic array works near the maximum output power point, and the energy utilization efficiency of the photovoltaic array can be improved.
In one embodiment, as shown in fig. 1, the main control chip includes a constant voltage output mode control loop; the above-described operation modes include a constant voltage output mode.
The constant voltage output mode control loop is used for switching the working mode of the wireless energy supply system into a constant voltage output mode through the control mode decision module when the real-time state of charge of the energy storage battery is in a full-charge state; the constant voltage output mode includes: the output voltage of the DC-DC converter is regulated so that the output voltage of the DC-DC converter is the same as the voltage of the energy storage battery.
In particular, the excessively high output voltage of the photovoltaic array can affect the service life of the energy storage battery, and in order to ensure that the energy storage battery works in a safe working mode, the invention also uses a constant voltage output mode control loop, wherein the constant voltage output mode control loop comprises the output voltage of the DC-DC converter
Figure SMS_12
Is a sampling element, a voltage comparison element, an adaptive closed-loop controller +.>
Figure SMS_13
. The output voltage of the DC-DC converter obtained by sampling +.>
Figure SMS_14
And a preset reference output voltage->
Figure SMS_15
Comparing to obtain a difference e, and an adaptive closed-loop controller +.>
Figure SMS_16
E, judging, and switching the wireless energy supply system into a constant-voltage output mode through a control mode decision module according to a judging result, and regulating the duty ratio of the DC-DC converter through PWM, so as to regulate the output voltage of the DC-DC converter>
Figure SMS_17
Limiting the output voltage of the DC-DC converter>
Figure SMS_18
So that it is the same as the full charge voltage of the energy storage battery.
According to the embodiment, the constant voltage output mode control loop is used for controlling the output voltage of the DC-DC converter, so that when the energy storage battery is in a full-power state, the output voltage of the DC-DC converter is the same as the voltage of the energy storage battery, the energy storage battery can be ensured to work in a safe working mode, and the service life of the energy storage battery is prolonged.
In an embodiment, the main control chip includes a constant current output mode control loop, and the working mode includes a constant current output mode.
The constant current output mode control loop is used for switching the working mode of the wireless energy supply system into a constant current output mode when the real-time charge state of the energy storage battery is not in a full charge state and the real-time output current of the DC-DC converter is higher than the safe charging current of the energy storage battery; the constant current mode includes: the duty cycle of the DC-DC converter is adjusted so that the output current of the DC-DC converter is the same as the safe charging current of the energy storage battery.
Specifically, as shown in FIG. 1, the constant current output mode control loop includes an output current
Figure SMS_19
Sampling link, current comparison link and self-adaptive closed-loop controller>
Figure SMS_20
. Wherein the output current +.>
Figure SMS_21
For the output current of the DC-DC converter, a current comparison means for comparing the output current +.>
Figure SMS_22
Magnitude between the current and the safe charging current of the energy storage battery, when the output current of the DC-DC converter is +.>
Figure SMS_23
When the safe charging current is larger than that of the energy storage battery, the self-adaptive closed-loop controller>
Figure SMS_24
Based on the judgment of the comparison result e, triggering a control mode decision module to switch the working mode of the wireless energy supply system to a constant current output mode, and outputting at constant currentIn the mode, the duty cycle of the DC-DC converter is regulated by the PWM module to make the output current +.>
Figure SMS_25
The same as the safe charging current of the energy storage battery.
According to the embodiment, the real-time output current of the DC-DC converter is monitored, and when the real-time output voltage is compared with the safe charging current of the energy storage battery, the working mode of the wireless energy supply system is switched to the constant-current output mode, so that the safe and reliable operation of the wireless energy supply system can be ensured while the output power of the photovoltaic array tends to be maximized, and the service life of the energy storage battery is prolonged.
In an embodiment, the wireless energy supply system further includes a laser emitting end, where the laser emitting end is configured to emit laser to the photovoltaic array, so that the photovoltaic array outputs the first voltage to the DC-DC converter by using laser energy; and the DC-DC converter is used for converting the first voltage into the second voltage so as to store electric energy by the energy storage battery.
Specifically, the wireless energy supply system provided by the invention can be applied to the conversion and utilization of sunlight, laser or other light energy, and the embodiment particularly provides a wireless energy supply system applied to the transmission and conversion of laser energy, as shown in fig. 1, the wireless energy supply system further comprises a laser emission end, wherein the laser emission end is used for emitting laser to a photovoltaic array so that the photovoltaic array converts the laser energy into a first voltage and outputs the first voltage to a DC-DC converter; the DC-DC converter is used for converting the first voltage into the second voltage so as to store electric energy for the energy storage battery or use the electric energy for the load. The main control chip of the DC-DC converter controls the working mode of the whole system, and the description is omitted here.
The above embodiment provides a wireless energy supply system applied to laser energy transmission, through which the problem that output power of a photovoltaic array is difficult to keep near a maximum power working point due to unstable laser light emission can be solved, and meanwhile, safe and stable operation of the laser energy wireless energy supply system can be ensured through the system, and the service life of an energy storage battery is prolonged.
In one embodiment, as shown in fig. 2, a closed-loop control method is provided, and the method is applied to the wireless energy supply system in fig. 1, where the DC-DC converter in the wireless energy supply system includes a main control chip, and the main control chip is configured to perform the following steps:
step 201, monitoring a real-time output voltage, a real-time output current of the DC-DC converter and a real-time state of charge of the energy storage battery.
The DC-DC converter, namely a DC conversion circuit, is used for converting the DC voltage output by the photovoltaic array into the DC voltage which can be used by an energy storage battery or a load; the main working mode is a pulse width modulation (Pulse Width Modulation, PWM, pulse width modulation) working mode, and the basic principle is that direct current is chopped into square waves (pulse waves) through a switching tube, and the voltage is changed by adjusting the duty ratio (the ratio of the pulse width to the pulse period) of the square waves. Alternatively, the DC-DC converter may be a buck converter or a boost converter. The energy storage battery is also called a storage battery and is used for storing the current output by the photovoltaic array, and the real-time charge state of the energy storage battery is used for reflecting the ratio of the residual capacity of the battery to the full capacity of the battery.
Specifically, the main control chip samples the input and output signals of the DC-DC converter, as shown in fig. 1, to obtain the real-time output voltage of the DC-DC converter
Figure SMS_26
Real-time output current->
Figure SMS_27
The main control chip can also acquire the real-time State of Charge (SOC) of the energy storage battery through sampling.
Step 202, judging the real-time output voltage
Figure SMS_28
Real-time output current->
Figure SMS_29
State conditions satisfied by the real-time state of charge SOC, rootAnd switching the working mode of the wireless energy supply system according to the state condition. The method specifically comprises the following steps: as shown in fig. 1, when the real-time state of charge SOC of the energy storage battery and the real-time output current of the DC-DC converter +>
Figure SMS_30
When the first state condition is met, determining that the working mode of the system is a maximum power tracking mode; the maximum power tracking mode includes: and regulating the duty ratio of the DC-DC converter through the PWM module to change the equivalent load of the photovoltaic array until the output power of the photovoltaic array reaches the maximum power in the current state.
The maximum power tracking mode is generally referred to as MPPT (Maximum Power Point Tracking ), and refers to adjusting the output power of the photovoltaic array according to different ambient temperatures, different illumination intensities, different self-operating characteristics of the photovoltaic array, and the like, so that the photovoltaic array always outputs the maximum power. The principle on which the maximum output power tracking method of the photovoltaic array is based is shown in fig. 3 (a) and 3 (b), wherein fig. 3 (a) shows an output voltage-output current curve (I-V curve) of the photovoltaic cell, fig. 3 (b) shows an output power-output voltage curve (P-U curve) of the photovoltaic cell, fig. 3 (a) and 3 (b),
Figure SMS_31
For equivalent load of photovoltaic cell, +.>
Figure SMS_32
Is the equivalent output voltage of the photovoltaic cell; p is the output power of the photovoltaic cell; d is the duty ratio of the DC-DC converter, the duty ratio D refers to the ratio of the pulse width to the pulse period of the pulse signal output by the DC-DC converter, and in the invention, the duty ratio of the DC-DC converter can be calculated according to the sampling value of the real-time output voltage of the DC-DC converter; in fig. 3 (a), point O is the maximum output power point of the photovoltaic cell, ray a is taken as a dividing line, the working characteristic curve above ray a is relatively gentle, the photovoltaic cell is basically constant current output, and the working characteristic curve below ray a can show that the output voltage of the photovoltaic cell is basically workingConstant voltage output is achieved; as is apparent from fig. 3 (b), the operating characteristic of the photovoltaic cell is nonlinear, under a certain environmental temperature and light intensity irradiation, as the output voltage increases, the output power becomes larger and smaller, and a maximum power point appears in the P-U curve, so that the MPPT operating principle is to make full use of the operating characteristic of the photovoltaic cell to make it operate at the maximum output power point, and the output voltage and the output current of the photovoltaic cell are changed until the output power is maximum by adjusting the equivalent load of the photovoltaic cell. The maximum output power point is also affected by environmental conditions such as temperature and light intensity, for example, the maximum output power of the photovoltaic array at noon is 500W, and the maximum output power of the photovoltaic array at noon is possibly 800W, so that it is necessary to find and track the maximum power point of the photovoltaic cell in the current state so as to keep the photovoltaic cell working efficiently all the time; in addition, the photovoltaic array is easily interfered by surrounding environment (such as clouds, buildings, tree shading and the like) and dust on the surface of the battery plate in the use process, so that the output power of the photovoltaic array is reduced, the output characteristic curve becomes complex, for example, the output characteristic curve is multi-pole (multi-peak), and the maximum power point of the photovoltaic cell is more needed to be found by using MPPT.
Specifically, in order to maintain the maximum power output of the photovoltaic array and simultaneously ensure that the whole wireless energy supply system safely and stably operates, the invention uses a control mode decision module to determine or switch the working mode of the whole system according to the acquired real-time state parameters; the control mode decision module realizes the on-off of the corresponding switch circuit according to the real-time state parameter, and when the real-time state parameter meets the corresponding state condition, the maximum power tracking mode control loop, the constant voltage output mode control loop or the constant current output mode control loop as shown in fig. 1 is used for adjusting the output voltage or the output current of the photovoltaic array.
According to the embodiment, the real-time state parameters in the wireless energy supply system are monitored in real time through the main control chip in the DC-DC converter, the state conditions met by the wireless energy supply system are judged through the relation among the real-time state parameters, and the working mode of the wireless energy supply system is adaptively adjusted according to the state conditions, so that the wireless energy supply system can ensure safe and stable operation of the wireless energy supply system while meeting the maximum power output, the energy efficient conversion and utilization of the whole wireless energy supply system are ensured, and the dynamic performance and stability of the wireless energy supply system can be ensured when the wireless energy supply system is disturbed or the working mode is switched.
As shown in fig. 4, fig. 4 is a schematic overall flow chart of the maximum power tracking method; after sampling to obtain the real-time output voltage and the real-time output current of the DC-DC converter and the real-time state of charge (SOC) of the energy storage battery, carrying out signal conditioning amplification and A/D conversion (alternating current/direct current conversion) on the sampled signals, judging the working mode required by the current system by comparing the magnitude relation of each parameter, firstly judging whether voltage and current protection is required, and if not, running a maximum power tracking algorithm, so that the photovoltaic array runs at the maximum output power working point in the real-time state.
In one embodiment, the step 202 includes: when the real-time state of charge SOC of the energy storage battery is not in a full state and the real-time output current of the DC-DC converter is not higher than the safe charging current of the energy storage battery, determining that the wireless energy supply system does not need output voltage protection or output current protection, and the currently required working mode is a maximum power tracking mode, where the maximum power tracking mode includes: as shown in fig. 4, the duty ratio D of the DC-DC converter is adjusted by the PWM module to change the equivalent load of the photovoltaic array, that is, the output power of the photovoltaic array, until the output power of the photovoltaic array reaches the maximum power in the current environmental state, and maintain the maximum power output. If the change of the light intensity received by the photovoltaic array or the change of the temperature of the photovoltaic array is detected, the maximum power point of the photovoltaic array is changed, the maximum power point applicable to the current light intensity or the temperature is continuously searched, and the output power of the photovoltaic array is adjusted to the latest maximum power point.
Further, under the condition that the light intensity or the temperature is unchanged, if the load changes, the duty ratio D of the DC-DC converter is adjusted through the PWM module, so that the equivalent load of the photovoltaic array changes, namely the output power of the photovoltaic array changes, and the load is powered. If the load is unchanged, the current maximum power output is maintained.
According to the embodiment, under the condition that the energy storage battery is not in the full-power state and the output current of the DC-DC converter is not higher than the safe charging current of the energy storage battery, the duty ratio is adjusted so that the photovoltaic battery always works near the maximum power point in the real-time environment state, the maximum power output capacity of the photovoltaic system can be ensured, and the energy use efficiency of the photovoltaic system is ensured to be maximized.
In one embodiment, the step 202 further includes: when the real-time charge state of the energy storage battery is in a full-charge state, switching the working mode of the wireless energy supply system into a constant-voltage output mode; the constant voltage output mode includes: the duty cycle of the DC-DC converter is adjusted so that the output voltage of the DC-DC converter is the same as the full charge voltage of the energy storage battery.
Because the working state of the energy storage battery is also influenced by the environment (such as self temperature) and the load, for example, when the energy storage battery is in a full-power state, the service life of the energy storage battery is influenced by the excessively high output voltage of the DC-DC converter, so that the output voltage and the output current of the photovoltaic array are required to be adapted to the state of charge (SOC) of the energy storage battery, the working efficiency of the whole system is effectively utilized to the greatest extent, and the service life of the energy storage battery can be considered, so that the invention also uses a voltage protection or current protection mechanism.
Specifically, when the real-time state of charge SOC of the energy storage battery is in a full state of charge; that is, as long as the real-time state of charge SOC of the energy storage battery is determined to be in the full state, the wireless energy supply system is preferentially controlled to enter the constant voltage output mode regardless of the output current of the DC-DC converter. As shown in fig. 1, the working mode of the wireless energy supply system is switched into a constant voltage output mode by a control mode decision module; the constant voltage output mode includes: regulating the output voltage of the DC-DC converter, i.e. by regulating the duty cycle D of the DC-DC converter by means of a pulse width modulation module (PWM module)
Figure SMS_33
So that the output voltage of the DC-DC converter +.>
Figure SMS_34
The same as the full voltage of the energy storage battery.
According to the embodiment, when the real-time state of charge (SOC) of the energy storage battery is in the full-charge state, the working mode of the wireless energy supply system is switched to the constant-voltage output mode, so that the energy storage battery is protected, and the service life of the energy storage battery is prolonged.
In one embodiment, the step 202 further includes: when the real-time state of charge (SOC) of the energy storage battery is not in a full state, and the real-time output current of the DC-DC converter
Figure SMS_35
When the safe charging current is higher than the safe charging current of the energy storage battery, the working mode of the wireless energy supply system is switched to a constant current output mode; the constant current output mode includes: the duty cycle of the DC-DC converter is adjusted so that the output current of the DC-DC converter is the same as the safe charging current of the energy storage battery.
Specifically, when the real-time state of charge (SOC) of the energy storage battery is not in a full state, and the real-time output current of the DC-DC converter
Figure SMS_36
When the current is higher than the safe charging current of the energy storage battery, as shown in fig. 1, the working mode of the wireless energy supply system is switched into a constant current output mode through a control mode decision module; the constant current output mode includes: i.e. the duty cycle D of the DC-DC converter is regulated by a pulse width modulation module (PWM module) to achieve regulation of the output current of the DC-DC converter +.>
Figure SMS_37
So that the output current of the DC-DC converter is +.>
Figure SMS_38
The same as the safe charging current of the energy storage battery.
The embodiment is that in the energy storage batteryThe real-time state of charge SOC of (2) is not in full state and the real-time output current of the DC-DC converter
Figure SMS_39
When the safe charging current is higher than the safe charging current of the energy storage battery, the working mode of the wireless energy supply system is switched to the constant current output mode, so that the energy storage battery is protected, and the service life of the energy storage battery is prolonged.
In an embodiment, the maximum power tracking mode further includes: taking the duty ratio of the DC-DC converter as a position variable of each particle in the particle swarm, and performing iterative calculation on the position variable of each particle by using a particle swarm optimization algorithm based on predation search strategy to obtain the global optimal position of the particle swarm; and calculating the output voltage of the photovoltaic array and the corresponding maximum output power based on the global optimal position (namely the optimal duty ratio).
The PSO (Particle Swarm Optimization ) algorithm firstly initializes a group of particles in a feasible solution space, each particle represents a potential optimal solution of the extremum optimizing problem, and three indexes of position variable, speed variable and fitness value are used for representing the particle characteristics. The particles move in the solution space, and the individual position is updated by tracking an individual extremum (individual optimal position) and a population extremum (population optimal position), wherein the individual extremum refers to a position corresponding to the position where the fitness value calculated in the positions experienced by the individual is optimal, and the population extremum refers to a position corresponding to the position where the fitness searched by all the particles in the population is optimal. Each time the particle updates a position, a fitness value is calculated and the individual extremum and the population extremum are updated by comparing the fitness value, the individual extremum, the population extremum of the particle.
Specifically, the invention uses a particle swarm optimization algorithm (PS-PSO, priority Search-Particle Swarm Optimization) based on a predation Search strategy to realize tracking of the maximum output power point of the photovoltaic array. The specific flow is as follows.
In an embodiment, as shown in fig. 5, fig. 5 shows a control flow diagram of the maximum power tracking mode, including:
Step 501, determining a global search space of a duty cycle of a DC-DC converter, and dividing the global search space into a plurality of different levels of subspaces.
Since the present application uses an improved particle swarm optimization algorithm, i.e. a particle swarm optimization algorithm PS-PSO based on predation search strategies. When the predation search strategy is optimized, global search is firstly carried out in the whole search space until a better solution is found; then concentrated searching is carried out in the area near the better solution, and if the better solution is not found for many times, local searching is abandoned; then global searching is performed in the whole searching space, and the method is circulated until the optimal solution (or the approximate optimal solution) is found. Specifically, prior to initializing population sizes, a global search space is required that first determines the positional variables of the particles
Figure SMS_42
The method comprises the steps of carrying out a first treatment on the surface of the Global search space +.>
Figure SMS_44
Dividing into mutually non-overlapping subspaces, and determining the level of the subspaces according to the adjacent relation of the subspaces>
Figure SMS_46
Obtaining subspaces of different grades +.>
Figure SMS_41
The method comprises the steps of carrying out a first treatment on the surface of the As shown in FIG. 6, subspace +.>
Figure SMS_43
Is +.>
Figure SMS_45
,/>
Figure SMS_47
Is +.>
Figure SMS_40
… … and so on.
Step 502, determining a subspace of a current level to be searched.
In particular, for example, to determine
Figure SMS_48
The current level is 1 for the subspace to be searched.
Step 503, obtaining an initial value in the subspace of the current level; the initial value includes a particle swarm size, an initial velocity of each particle in the particle swarm, and an initial position of each particle subject to a current level of subspace.
As shown in fig. 7, fig. 7 shows another flowchart of the PS-PSO algorithm, and the PS-PSO algorithm is described in detail with reference to fig. 7: determining a current limit area to be searched as
Figure SMS_49
After that, at->
Figure SMS_50
Initializing m particles internally; specifically, the population size m of the particle swarm is initialized, that is, m particles are all, and the initial position of each particle is the subspace of the current level +.>
Figure SMS_51
Arbitrary values within, and at the same time, the initial velocity of each particle is obtained.
Step 504, performing iterative optimization in the subspace of the current level, and updating the locally optimal solution in each iteration (i.e. in the current subspace
Figure SMS_52
The optimal position of the group in the set) until a better solution is obtained in the preset maximum iteration number.
Wherein the above-mentioned local optimum solution
Figure SMS_53
Namely the whole particle swarm is in the current subinterval +.>
Figure SMS_54
The extremum of the population (i.e., the optimum position of the population) that can be found.
Specifically, as shown in fig. 7, iterative optimization is performed by the PSO algorithm: in the current limit area
Figure SMS_55
In the current iteration, updating the speed and the position of each particle, calculating the current corresponding adaptation value of the particle through a preset fitness function, judging whether the current adaptation value is smaller or larger than the adaptation value corresponding to the last time when the individual optimal position is acquired (the individual adaptation value judgment condition can be determined according to the actual situation), and taking the current position as the individual optimal position if the preset adaptation value judgment condition is met, otherwise, keeping unchanged; calculating an adaptation value corresponding to each particle in the whole particle swarm, selecting the minimum or maximum adaptation value, taking the particle position corresponding to the individual adaptation value as the group optimal position if the adaptation value is smaller than or larger than the adaptation value corresponding to the last group optimal position (according to the group adaptation value judgment condition determined by actual conditions), adding 1 to the iteration number, until the preset iteration number is reached, terminating the iteration to obtain the current subinterval, wherein the group optimal position is unchanged if the preset group adaptation value judgment condition is not met>
Figure SMS_56
Within population optimal position->
Figure SMS_57
(i.e., a more optimal solution).
Step 505, determining whether the above preferred solution meets a preset history extremum determining condition (for example, greater than or less than the last stored history optimal solution), if yes, using the above preferred solution as the history optimal solution
Figure SMS_58
) The method comprises the steps of carrying out a first treatment on the surface of the If not, keeping the last historical optimal solution unchanged. Updating the level according to the level relation to obtain a current subspace after updating the level; returning to step 502.
Specifically, using the better solution as a history optimal solution, updating the level according to the level relation, and obtaining a current subspace after updating the levelSteps 502-505 are circularly executed until the limit level reaches the preset level, and the current obtained historical optimal solution is obtained
Figure SMS_59
As global search space->
Figure SMS_60
And the global optimal solution on the power point is the duty ratio corresponding to the global maximum power point.
In particular, if in
Figure SMS_61
PSO algorithm iteration under restriction level>
Figure SMS_62
After the next time no better solution is found, the restriction level is adjusted to +.>
Figure SMS_63
And so on, when the limit level reaches a certain value, if the history optimal solution still cannot be continuously updated
Figure SMS_64
In order to reduce the search time and jump out of the local optimum, the search area level is adjusted to be higher to jump out of the local search. The search strategy is used for circulation and progression until the limit level reaches +. >
Figure SMS_65
I.e. global restricted area, where the search task is completed, the resulting historical optimal solution +.>
Figure SMS_66
The global optimal solution on the space omega is the global maximum power point.
According to the embodiment, the particle position searching process is realized through the PS-PSO algorithm, the invalid searching time is reduced, the algorithm convergence speed is further increased, the probability of the algorithm falling into a local optimal solution is further reduced, the operation efficiency of the whole wireless energy supply system is further improved, the wireless energy supply system can quickly track the maximum power point when being disturbed or switching the working mode, and the dynamic performance and stability of the working of the wireless energy supply system are improved.
In an embodiment, after the step 201, the method further includes: and after the real-time output voltage and the real-time output current of the DC-DC converter and the real-time state of charge of the energy storage battery are subjected to weighted comparison by using a preset weight function, judging the state condition met by the photovoltaic array wireless energy supply system according to the comparison result.
Specifically, as shown in fig. 8, fig. 8 illustrates an adaptive closed-loop controller in a wireless power supply system
Figure SMS_67
Since the operation characteristic of the photovoltaic cell is nonlinear, and the operation characteristic curves are shown in fig. 3 (a) and 3 (b), in order to make the photovoltaic cell operate near the maximum power point, the invention uses a linear weight compensator to realize closed-loop stable control of the photovoltaic array under different operation states, wherein the linear weight compensator comprises a weight function, the weight function can output a decimal between 0 and 1 as a weight value, and the weight function is based on the input voltage of the DC-DC converter V pv Maximum power reference voltage V ref Input voltage V to DC-DC converter pv Difference betweeneCalculating weights in a linear weighted compensatorw 1w 2 Andw 3 and is based on->
Figure SMS_68
、/>
Figure SMS_69
、/>
Figure SMS_70
A weighted sum of the weights corresponding to the control mode, wherein->
Figure SMS_71
、/>
Figure SMS_72
、/>
Figure SMS_73
Respectively PID controllers (Proportion Integration Differentiation, proportional-integral-derivative controllers).
According to the embodiment, the linear weighted compensator is designed according to the characteristics of the output characteristics of the photovoltaic cell in different working areas, and the nonlinear output of the photovoltaic cell is subjected to self-adaptive compensation, so that the dynamic performance and stability of the photovoltaic cell are ensured when the photovoltaic cell is subjected to disturbance (such as illumination change) or when the working mode is switched, and the method is further suitable for closed-loop control when different disturbance occurs in a maximum power tracking control mode.
The following is a description of one specific application of the above wireless power supply system:
because the output voltage and current of a single photovoltaic cell are small, in practical applications, the photovoltaic cells are typically combined in series and parallel to increase the capability of the photovoltaic system to output voltage and current. In one specific verification case of the present invention, four groups of photovoltaic cell modules are selected for series connection, as shown in fig. 9. Parameters of each group of photovoltaic cell assemblies V ocI scV mppI mpp ) As shown in table 1. And constructing a circuit model of the laser wireless energy supply system based on the staggered parallel Boost converter, and carrying out experimental verification on the effectiveness of a closed-loop control algorithm and a maximum power tracking algorithm, wherein the Boost converter is one of DC-DC converters, and the specific circuit structure is shown in figure 10.
Table 1 MPPT algorithm simulation system parameters
Figure SMS_74
As can be seen from simulation, when the output characteristics of the photovoltaic cell array are under the conditions of single peak, two peaks, three peaks and four peaks, the running result of the maximum power tracking algorithm designed by the invention is shown in figure 11. The graph shows that the global multi-peak maximum power tracking algorithm designed by the invention can realize global maximum power tracking of the photovoltaic cell under different output conditions.
In order to verify the dynamic performance of the laser wireless energy supply system when the system illumination condition changes, and the effectiveness of the closed-loop control algorithm and the maximum power tracking algorithm on the stable control of the system when the system is switched under different working states. The output characteristics of the photovoltaic cells are dynamically changed at different moments, that is, the photovoltaic cell outputs are sequentially switched from a single peak to a four peak condition, and the dynamic changes of the output power, the output voltage (i.e., the input voltage of the DC-DC converter) and the output current (i.e., the input current of the DC-DC converter) of the photovoltaic array are shown in fig. 12 (a), 12 (b) and 12 (c), respectively. The graph shows that the closed-loop control algorithm and the global multi-peak maximum power tracking algorithm designed by the invention have good control performance, and can meet the stable control of the system under large signal disturbance.
Fig. 13 illustrates a physical structure diagram of an electronic device, as shown in fig. 13, which may include: processor 1310, communication interface (Communications Interface) 1320, memory 1330 and communication bus 1340, wherein processor 1310, communication interface 1320, memory 1330 communicate with each other via communication bus 1340. Processor 1310 may invoke logic instructions in memory 1330 to perform a closed loop control method or a maximum power tracking method, the closed loop control method comprising: monitoring the real-time output voltage, the real-time output current and the real-time state of charge of the energy storage battery of the DC-DC converter; and determining the working mode of the wireless energy supply system according to the state conditions met by the real-time output voltage, the real-time output current and the real-time state of charge of the energy storage battery of the DC-DC converter. The maximum power tracking method comprises the following steps: monitoring a real-time output voltage, a real-time output current of the DC-DC converter and a real-time state of charge of the energy storage battery; when the real-time state of charge of the energy storage battery is not in a full-charge state and the real-time output current of the DC-DC converter is not higher than the safe charging current of the energy storage battery, determining that the working mode of the wireless energy supply system is a maximum power tracking mode; the maximum power tracking mode includes: and adjusting the duty ratio of the DC-DC converter to change the output power of the photovoltaic array until the output power of the photovoltaic array reaches the maximum output power in the current environment state.
Further, the logic instructions in the memory 1330 can be implemented in the form of software functional units and can be stored in a computer readable storage medium when sold or used as a stand alone product. Based on this understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
In another aspect, the present invention also provides a computer program product, where the computer program product includes a computer program, where the computer program can be stored on a non-transitory computer readable storage medium, where the computer program, when executed by a processor, can perform a closed-loop control method or a maximum power tracking method provided by the above methods, where the closed-loop control method includes: monitoring the real-time output voltage, the real-time output current and the real-time state of charge of the energy storage battery of the DC-DC converter; and determining the working mode of the wireless energy supply system according to the state conditions met by the real-time output voltage, the real-time output current and the real-time state of charge of the energy storage battery of the DC-DC converter. The maximum power tracking method comprises the following steps: monitoring a real-time output voltage, a real-time output current of the DC-DC converter and a real-time state of charge of the energy storage battery; when the real-time state of charge of the energy storage battery is not in a full-charge state and the real-time output current of the DC-DC converter is not higher than the safe charging current of the energy storage battery, determining that the working mode of the wireless energy supply system is a maximum power tracking mode; the maximum power tracking mode includes: and adjusting the duty ratio of the DC-DC converter to change the output power of the photovoltaic array until the output power of the photovoltaic array reaches the maximum output power in the current environment state.
In yet another aspect, the present invention further provides a non-transitory computer readable storage medium having stored thereon a computer program which, when executed by a processor, is implemented to perform a closed loop control method or a maximum power tracking method provided by the above methods, the closed loop control method comprising: monitoring the real-time output voltage, the real-time output current and the real-time state of charge of the energy storage battery of the DC-DC converter; and determining the working mode of the wireless energy supply system according to the state conditions met by the real-time output voltage, the real-time output current and the real-time state of charge of the energy storage battery of the DC-DC converter. The maximum power tracking method comprises the following steps: monitoring a real-time output voltage, a real-time output current of the DC-DC converter and a real-time state of charge of the energy storage battery; when the real-time state of charge of the energy storage battery is not in a full-charge state and the real-time output current of the DC-DC converter is not higher than the safe charging current of the energy storage battery, determining that the working mode of the wireless energy supply system is a maximum power tracking mode; the maximum power tracking mode includes: and adjusting the duty ratio of the DC-DC converter to change the output power of the photovoltaic array until the output power of the photovoltaic array reaches the maximum output power in the current environment state.
The system embodiments described above are merely illustrative, wherein the elements illustrated as separate elements may or may not be physically separate, and the elements shown as elements may or may not be physical elements, may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present invention without undue burden.
From the above description of the embodiments, it will be apparent to those skilled in the art that the embodiments may be implemented by means of software plus necessary general hardware platforms, or of course may be implemented by means of hardware. Based on this understanding, the foregoing technical solution may be embodied essentially or in a part contributing to the prior art in the form of a software product, which may be stored in a computer readable storage medium, such as ROM/RAM, a magnetic disk, an optical disk, etc., including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method described in the respective embodiments or some parts of the embodiments.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (16)

1. The wireless energy supply system is characterized by comprising a photovoltaic array, a DC-DC converter and an energy storage battery; the photovoltaic array is connected with the energy storage battery through the DC-DC converter; the DC-DC converter comprises a main control chip; wherein,,
the main control chip is used for monitoring the real-time output voltage and the real-time output current of the DC-DC converter and the real-time charge state of the energy storage battery;
the main control chip is also used for determining the working mode of the wireless energy supply system according to the real-time output voltage and the real-time output current of the DC-DC converter and the state conditions met by the real-time state of charge of the energy storage battery.
2. The wireless power supply system of claim 1 wherein said master control chip includes a maximum power tracking mode control loop; the working modes comprise a maximum power tracking mode;
the maximum power tracking mode control loop is further configured to determine that the working mode of the wireless energy supply system is a maximum power tracking mode when the real-time state of charge of the energy storage battery is not in a full state and the real-time output current of the DC-DC converter is not higher than the safe charging current of the energy storage battery;
the maximum power tracking mode includes: and adjusting the duty ratio of the DC-DC converter to change the output power of the photovoltaic array until the output power of the photovoltaic array reaches the maximum power in the current state.
3. The wireless energy supply system of claim 1, wherein the master control chip comprises a constant voltage output mode control loop; the working mode comprises a constant voltage output mode;
the constant voltage output mode control loop is used for switching the working mode into a constant voltage output mode when the real-time state of charge of the energy storage battery is in a full state;
The constant voltage output mode includes: and adjusting the output voltage of the DC-DC converter so that the output voltage of the DC-DC converter is the same as the full-charge voltage of the energy storage battery.
4. The wireless energy supply system of claim 1, wherein the main control chip comprises a constant current output mode control loop, and the working mode comprises a constant current output mode;
the constant current output mode control loop is used for switching the working mode of the wireless energy supply system into a constant current output mode when the real-time charge state of the energy storage battery is not in a full charge state and the real-time output current of the DC-DC converter is higher than the safe charging current of the energy storage battery; the constant current output mode includes: the duty cycle of the DC-DC converter is adjusted such that the output current of the DC-DC converter is the same as the safe charging current of the energy storage battery.
5. The wireless power supply system of any one of claims 1 to 4, wherein said system further comprises a laser emitting end; wherein,,
the laser emission end is used for emitting laser to the photovoltaic array so that the photovoltaic array converts laser energy into first voltage and outputs the first voltage to the DC-DC converter;
The DC-DC converter is used for converting the first voltage into a second voltage so as to enable the energy storage battery to store electric energy.
6. A closed loop control method applied to the wireless power supply system according to any one of claims 1 to 5, comprising:
monitoring a real-time output voltage, a real-time output current of the DC-DC converter and a real-time state of charge of the energy storage battery;
and determining the working mode of the wireless energy supply system according to the state conditions met by the real-time output voltage, the real-time output current and the real-time state of charge of the energy storage battery of the DC-DC converter.
7. The method of claim 6, wherein determining the operating mode of the wireless energy supply system based on the state conditions satisfied by the real-time output voltage, the real-time output current, and the real-time state of charge of the energy storage battery of the DC-DC converter comprises:
when the real-time state of charge of the energy storage battery is in a full-charge state, switching the working mode of the wireless energy supply system into a constant-voltage output mode; the constant voltage output mode includes: the duty cycle of the DC-DC converter is adjusted so that the output voltage of the DC-DC converter is the same as the full charge voltage of the energy storage battery.
8. The closed loop control method of claim 6, comprising:
when the real-time charge state of the energy storage battery is not in a full-charge state and the real-time output current of the DC-DC converter is higher than the safe charging current of the energy storage battery, switching the working mode of the wireless energy supply system into a constant-current output mode; the constant current output mode includes: and adjusting the duty ratio of the DC-DC converter so that the output current of the DC-DC converter is the same as the safe charging current of the energy storage battery.
9. A maximum power tracking method applied to the wireless energy supply system according to any one of claims 1 to 5, comprising:
monitoring a real-time output voltage, a real-time output current of the DC-DC converter and a real-time state of charge of the energy storage battery;
when the real-time state of charge of the energy storage battery is not in a full-charge state and the real-time output current of the DC-DC converter is not higher than the safe charging current of the energy storage battery, determining that the working mode of the wireless energy supply system is a maximum power tracking mode; the maximum power tracking mode includes: and adjusting the duty ratio of the DC-DC converter to change the output power of the photovoltaic array until the output power of the photovoltaic array reaches the maximum output power in the current environment state.
10. The maximum power tracking method of claim 9, wherein the maximum power tracking mode further comprises:
taking the duty ratio of the DC-DC converter as a position variable of particles in a particle swarm, and iteratively updating the position variable of the particles by using a particle swarm optimization algorithm based on predation search strategy to obtain a global optimal position of the particle swarm;
and calculating the output voltage of the photovoltaic array based on the global optimal position, and obtaining the maximum output power of the wireless energy supply system corresponding to the output voltage in the current environment state.
11. The maximum power tracking method of claim 9, wherein the maximum power tracking mode further comprises:
determining a global search space of a duty cycle of the DC-DC converter, and dividing the global search space into a plurality of subspaces of different levels;
determining a subspace of a current level to be searched;
initializing a particle swarm scale and a maximum iteration number in the subspace of the current level;
performing iterative optimization in the subspace of the current level, and updating a local optimal solution according to a preset fitness function until a better solution is obtained within a preset maximum iteration number;
Taking the better solution as a historical optimal solution, and updating the level according to the level relation to obtain an updated subspace of the current level; and returning to the step of determining the subspace of the current level to be searched.
12. The maximum power tracking method as claimed in claim 11, further comprising:
if no better solution exists in the preset maximum iteration times, updating the level according to the level relation, obtaining an updated subspace of the current level, returning to the subspace of the current level to be searched, until the updated level reaches the preset level, and outputting the current obtained historical optimal solution;
and taking the currently obtained historical optimal solution as a global optimal solution in the global search space.
13. The method of any one of claims 9 to 12, wherein after monitoring the real-time output voltage, the real-time output current, and the real-time state of charge of the energy storage battery of the DC-DC converter, further comprising:
and after the real-time output voltage and the real-time output current of the DC-DC converter and the real-time charge state of the energy storage battery are subjected to weighted comparison by using a preset weight function, judging the state condition met by the photovoltaic array wireless energy supply system according to the comparison result.
14. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the closed loop control method according to any one of claims 6 to 8 or the maximum power tracking method according to any one of claims 9 to 13 when executing the program.
15. A non-transitory computer readable storage medium having stored thereon a computer program, wherein the computer program when executed by a processor implements the closed loop control method of any of claims 6 to 8 or the maximum power tracking method of any of claims 9 to 13.
16. A computer program product comprising a computer program, characterized in that the computer program, when executed by a processor, implements the closed loop control method of any of claims 6 to 8 or the maximum power tracking method of any of claims 9 to 13.
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