CN107332301B - Energy control method of laser wireless power transmission system based on efficiency optimization - Google Patents
Energy control method of laser wireless power transmission system based on efficiency optimization Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
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Abstract
The invention discloses an energy control method of a laser wireless power transmission system based on efficiency optimization, and belongs to the technical field of laser wireless power transmission. The energy control strategy mainly comprises an optimal efficiency control strategy and an energy management optimization strategy, wherein the optimal efficiency control strategy searches an optimal system efficiency working point by gradually reducing the pulse width of the input pulse current of the laser on the premise that the output power of the photovoltaic array meets the requirements of a load and the power of a storage battery, the optimal energy management strategy further reduces the pulse width of the input current of the laser to search the optimal system working point by taking the system efficiency and the system charging power as control targets, properly reduces the average output power of the laser in the process of searching the optimal system working point to maintain the output voltage pulse of the photovoltaic array within a limited range, avoids the photovoltaic array efficiency from being influenced by overlarge voltage pulse, and further enables the system to work at the optimal efficiency point while meeting the requirement of quick charging of the storage battery.
Description
Technical Field
The invention discloses an energy control method of a laser wireless power transmission system based on efficiency optimization, and belongs to the technical field of laser wireless power transmission.
Background
With the increasing popularization of electrical equipment, the traditional power supply mode mainly based on contact conduction has the problems of poor mobility, insecurity, reliability and the like. Especially in the system that consumer and power supply system have relative removal, for satisfying the more additional equipment of physical contact needs, the application that has brought the inconvenience for the consumer, and wireless laser power transmission has the advantage that transmission distance is far away, the directionality is good, is suitable for carrying out non-contact charging to fast moving targets such as unmanned aerial vehicle, tank, vehicle.
As shown in fig. 1, in the laser wireless power transmission system, electric energy in a power grid or an energy storage unit is provided to a laser in a laser emitting end through a laser power supply, the laser converts the electric energy into laser and transmits the laser, a high-concentration photovoltaic cell in a laser receiving end converts the laser with high energy density into electric energy, and the electric energy is provided to a load and a storage battery after being converted by a power converter. At present, under the condition of not considering laser space transmission loss and system tracking loss, the overall efficiency of the system is only about 14% at most, wherein the energy conversion efficiency of a laser and a photovoltaic array is low, and the overall efficiency of the system is low, so that the practical application of the technology is limited. Therefore, research is carried out on the whole of the laser and the photovoltaic array, and the core of research on the laser wireless power transmission technology is to improve the whole efficiency of the system so as to meet the requirement of rapid and efficient power supply of mobile electrical equipment.
At present, the research on the laser wireless power transmission technology mostly focuses on the improvement of the performance of each part of the system, and the research from the viewpoint of the overall performance of the system is less. The laser is transmitted in the atmosphere, so that the optical power is lost due to atmospheric refraction, aerosol scattering and absorption and the like, and the optical power loss causes unstable power supply of the system and reduced efficiency. Therefore, the transmitting end and the receiving end need to be organically combined to realize the coordinated control of the system energy.
In addition, most of the existing systems adopt a semiconductor laser with high efficiency, and the output power and the electro-optical conversion efficiency of the semiconductor laser are in direct proportion to the input current of the semiconductor laser according to the characteristics of the semiconductor laser, which means that the system cannot constantly work at an operating point with optimal efficiency in the whole operating range, and the efficiency is low particularly under the condition of transmitting low power. Therefore, based on the above consideration that the efficiency varies with the variation of the operating point, the operating points of the laser and the photovoltaic array need to be optimized from the system point of view so as to obtain the optimal conversion efficiency all the time under any condition, thereby improving the overall conversion efficiency of the system.
In conclusion, key factors and rules for optimizing system efficiency are explored, and a system energy management strategy is proposed to improve the stability and the efficiency of system power supply, so that the method has important theoretical significance and practical application value for developing the research of the basic theory and the key technology of laser wireless power transmission.
Disclosure of Invention
The invention aims to provide an energy control method of a laser wireless electric energy transmission system based on efficiency optimization aiming at the defects of the background technology, which improves the overall conversion efficiency of the system while ensuring the power balance among the energy sources of the system and solves the technical problem that the energy management aiming at the laser wireless electric energy transmission system is lacked at present.
The invention adopts the following technical scheme for realizing the aim of the invention:
the energy control method of the laser wireless power transmission system based on efficiency optimization comprises the following steps: an efficiency-optimized control strategy and an energy management optimization strategy,
the system is initialized and then operated under an efficiency optimal control strategy, the efficiency optimal control strategy is based on the premise that the output power of the photovoltaic array meets the requirements of loads and storage battery power, the instantaneous emission light power of the laser is changed by adjusting the pulse width and the peak value of the input pulse current of the laser, so that the working points of the laser and the photovoltaic array are adjusted to ensure that the system works at the efficiency optimal point, and the system is switched to an energy management optimization strategy only when the pulse width of the input pulse current of the laser is not reduced to the preset minimum pulse width but the output voltage pulse of the photovoltaic array exceeds the limit value,
the energy management optimization strategy aims to meet the requirement of quick charging of a storage battery and enable the system to work at an efficiency optimal point, the system working point is further adjusted in a mode of gradually reducing the pulse width of the input pulse current of the laser to improve the efficiency of the system, and the average emitted light power of the laser is reduced in a mode of reducing the peak value of the input pulse current of the laser to maintain the pulsation of the output voltage of the photovoltaic array within a limited range.
As a further optimization scheme of the energy control method of the laser wireless power transmission system based on efficiency optimization, an efficiency optimization control strategy takes photovoltaic array output power, photovoltaic array rear-stage bus voltage and laser input pulse current pulse width as control variables, takes system efficiency as a control target, and ensures that the system works at an efficiency optimization point on the premise that the photovoltaic array output power meets the power requirements of a load and a storage battery, and specifically comprises the following steps:
the average value of the laser input current reference is changed through feedback control to ensure that the photovoltaic array output power meets the power requirements of the load and the storage battery: when the output power of the photovoltaic array does not meet the power requirements of a load and a storage battery, determining the average value of the input current reference of the laser according to the difference value of the output power of the photovoltaic array and the maximum value of the output power of the photovoltaic array, or else, determining the average value of the input current reference of the laser according to the difference value of the output power of the photovoltaic array and the maximum value of the output power of the photovoltaic array and the difference value of the post-stage bus voltage of the photovoltaic array and;
based on the idea of a perturbation method, determining the optimal point of the system efficiency by changing the pulse width of the input current of the laser: when the system efficiency at the current moment exceeds the system efficiency at the previous moment, the pulse width at the moment when the laser inputs the pulse current is reduced, the peak value at the moment when the laser inputs the pulse current is increased to maintain the output power of the photovoltaic array to be constant,
when the system efficiency at the current moment does not exceed the system efficiency at the previous moment, increasing the pulse width at the moment when the laser inputs pulse current, reducing the peak value at the moment when the laser inputs pulse current to maintain the output power of the photovoltaic array to be constant,
the input power of the laser at the next moment of the laser is sampled to determine the system efficiency at the next moment, the pulse width of the input pulse current of the laser is adjusted in real time according to the system efficiency, and the energy management optimization strategy is switched only when the pulse width of the input pulse current of the laser is not reduced to the preset minimum pulse width but the output voltage pulse of the photovoltaic array exceeds the limit value.
As a further optimization scheme of the energy control method of the laser wireless power transmission system based on efficiency optimization, an energy management optimization strategy takes the pulse width and the peak value of the input pulse current of a laser as control variables, takes system efficiency and system charging power as control targets, further reduces the pulse width of the input pulse current of the laser to search for an optimal working point of the system, and properly reduces the average output power of the laser in the process of searching for the optimal working point of the system to maintain the output voltage pulsation of a photovoltaic array within a limited range, so that the system can work at the optimal efficiency point while the rapid charging requirement of a storage battery is met, specifically:
when the weighted value of the system efficiency and the system charging power at the current moment exceeds the maximum value and the system efficiency at the current moment is greater than or equal to the system efficiency corresponding to the maximum output voltage pulsation of the photovoltaic array, taking the weighted value at the current moment as the maximum value, taking the pulse width of the laser input pulse current at the current moment as the optimal value of the pulse width of the laser input pulse current, taking the peak value of the laser input pulse current at the current moment as the optimal value of the peak value of the laser input pulse current, further reducing the pulse width at the moment under the laser input pulse current, and adjusting the peak value at the moment under the laser input pulse current to maintain the output voltage pulsation of the photovoltaic array within the limited range,
when the pulse width at the moment when the laser inputs the pulse current is smaller than the preset minimum pulse width, the optimal values of the pulse width and the peak value of the input pulse current of the laser are fed back to be the optimal working point of the system,
otherwise, sampling the input power of the laser at the next moment of the laser and the output power of the photovoltaic array to determine a weighted value at the next moment, and adjusting the pulse width and the peak value of the input pulse current of the laser in real time according to the weighted value;
when the weighted value of the system efficiency and the system charging power at the current moment does not exceed the maximum value of the weighted value or the system efficiency at the current moment is smaller than the system efficiency corresponding to the maximum output voltage pulsation of the photovoltaic array, the pulse width of the laser at the moment of inputting pulse current is reduced, the peak value of the laser at the moment of inputting pulse current is adjusted to maintain the output voltage pulsation of the photovoltaic array within the limited range, and the optimal control variable is fed back in real time or the input power of the laser and the output power of the photovoltaic array at the next moment of sampling are sampled according to the pulse width of the laser input pulse current.
As a further optimization scheme of the energy control method of the laser wireless power transmission system based on efficiency optimization, an average value of the input current reference of the laser is determined according to the difference value between the output power of the photovoltaic array and the maximum value thereof, specifically: and carrying out PI feedback regulation on the difference value of the output power of the photovoltaic array and the maximum value of the output power of the photovoltaic array.
As a further optimization scheme of the energy control method of the laser wireless power transmission system based on efficiency optimization, an average value of the input current reference of the laser is determined according to a difference value between the output power of the photovoltaic array and the maximum value thereof and a difference value between the voltage of the rear-stage bus of the photovoltaic array and the maximum value thereof, and the method specifically comprises the following steps: and respectively carrying out PI feedback regulation on the difference value between the output power of the photovoltaic array and the maximum value thereof and the difference value between the voltage of the photovoltaic array rear-stage bus and the maximum value thereof to obtain a PI regulation value of the output power deviation of the photovoltaic array and a PI regulation value of the voltage deviation of the photovoltaic array rear-stage bus, and taking the accumulated value of the PI regulation value of the output power deviation of the photovoltaic array and the PI regulation value of the voltage deviation of the photovoltaic array rear-stage bus as the average value of the input current reference of the laser.
As a further optimization scheme of the energy control method of the laser wireless power transmission system based on efficiency optimization, weighting values of system efficiency and system charging power at the current moment are expressed by:calculating, J (n) is the weighted value of the system efficiency and the system charging power at the current moment, eta*(n)、Is the per unit value of the system efficiency and the system charging power at the current moment respectively, a and b are the weighting coefficients of the per unit value of the system efficiency and the system charging power at the current moment, Pin_avg(n)、Ppv_avg(n) the input power of the laser, the output power of the photovoltaic array at the current moment, Pbat(n)、Pbat_maxAnd (n) respectively represent the charging power of the storage battery in the system at the current moment and the set maximum charging power.
By adopting the technical scheme, the invention has the following beneficial effects:
(1) considering that the research on energy management of a laser wireless power transmission system in the prior art is less, the invention provides an energy control strategy of the laser wireless power transmission system based on efficiency optimization, which mainly comprises an optimal efficiency control strategy and an optimal energy management optimization strategy, wherein the optimal efficiency control strategy searches an optimal system efficiency working point by gradually reducing the pulse width of input pulse current of a laser on the premise that the output power of a photovoltaic array meets the requirements of loads and storage battery power, the optimal energy management optimization strategy further reduces the pulse width of the input pulse current of the laser to search the optimal system working point, the average output power of the laser is properly reduced in the process of searching the optimal system working point to maintain the output voltage pulsation of the photovoltaic array in a limited range, the photovoltaic array efficiency is prevented from being influenced by overlarge voltage pulsation, so that the system works at an optimal efficiency point while the requirement of quick charging of the storage battery is met, the pulse width of LD pulse input current is optimized by the whole energy control method on the premise of ensuring the energy required by the load and the storage battery so as to improve the system efficiency, and the stability and the high efficiency of system power supply are improved;
(2) the energy management strategy provided by the invention is simple and convenient, the calculated amount is small, the switching between the modes is smooth, and the complex logic switching is avoided.
Drawings
FIG. 1 is a general block diagram of a laser power delivery system;
FIG. 2 is a graph of LD efficiency versus its average output optical power in continuous/pulsed mode;
FIG. 3 is a graph of the efficiency of a photovoltaic array under continuous/pulsed light irradiation;
FIG. 4 is a graph of the efficiency of the laser and photovoltaic array as a whole;
FIG. 5 is a control flow diagram of an energy management optimization strategy;
fig. 6 is a graph of experimental results of energy management of a laser wireless power transmission system.
Detailed Description
The technical scheme of the invention is explained in detail in the following with reference to the attached drawings.
In the Laser wireless power transmission system shown in fig. 1, a semiconductor Laser (LD) converts electric energy into Laser light, and the Laser light is transmitted to a remote photovoltaic receiver through a free space. At the receiving end, the photovoltaic array converts the laser light back into electric energy, and the electric energy is provided to the load and the energy storage unit after being converted by the converter. In which LD is a current injection type device, the input current of different characteristics has a significant effect on its efficiency.
Fig. 2 is a graph of the relationship between the efficiency of the LD and the average output optical power thereof in the continuous/pulse mode, and it can be seen from the graph that the efficiency of the LD is better when the input current is a pulse current, and the efficiency is higher when the pulse width of the current is smaller under the same output optical power.
Fig. 3 is an efficiency curve of the photovoltaic array under continuous/pulsed light irradiation, and it can be seen from the graph that the thermal effect of the photovoltaic array is more serious and the efficiency is lower as the average incident light power is higher, and the efficiency of the photovoltaic array is better under continuous light irradiation, while under pulsed light irradiation, the light pulse width is narrower and the efficiency of the photovoltaic array is lower.
From fig. 2 and fig. 3, the efficiency (the ratio of the average output power of the photovoltaic array to the average input power of the laser) of the laser and the photovoltaic array in the system can be obtained, as shown in fig. 4, it can be known that the pulse width of the LD input current is a factor affecting the overall power transmission efficiency, and the smaller the pulse width of the current, the higher the efficiency. Therefore, the energy management strategy aims to optimize the pulse width of the LD pulse input current and improve the system efficiency on the premise of ensuring the energy required by the load and the storage battery.
An energy control strategy based on efficiency optimization is shown in fig. 1, and mainly comprises an optimal efficiency control strategy and an energy management optimization strategy, wherein the optimal efficiency control strategy searches an optimal system efficiency working point by gradually reducing the pulse width of the input pulse current of the laser on the premise that the output power of the photovoltaic array meets the requirements of the load and the power of the storage battery. The energy management optimization strategy takes system efficiency and system charging power as control targets, further reduces the input current pulse width of the laser, properly reduces the average output power of the laser to maintain the output voltage pulsation of the photovoltaic array within a limited range in the process of searching the optimal working point of the system, avoids the influence of overlarge voltage pulsation on the efficiency of the photovoltaic array, and further enables the system to work at the optimal efficiency point while meeting the requirement of quick charging of the storage battery.
The energy control strategy based on efficiency optimization optimizes the pulse width of the LD pulse input current mainly based on the efficiency curve of the laser and photovoltaic array as a whole as shown in fig. 4, thereby improving the efficiency of the system. The main control idea is as follows: under the condition of ensuring that the average emitting power of the laser (namely the energy provided by the photovoltaic array to the load and the storage battery is unchanged), the instantaneous value of the emitting power of the laser is changed by optimizing the pulse width and the peak value of the LD pulse input current, so that the integral working point of the laser and the photovoltaic array is adjusted, and the integral working efficiency of the system is optimized.
The system firstly works in an efficiency optimal control strategy, and in order to ensure that the output power of the photovoltaic array meets the requirements of the load and the power of the storage battery, as shown in figure 1, the output power P of the photovoltaic array is selectedpvAnd the photovoltaic array post-stage bus voltage Vo is used as a control variable, and the average value i of the laser input current reference is usedDC_refAs a control target. When the output power of the photovoltaic array cannot meet the sum of the load and the power required by the charging of the storage battery, the bus voltage at the receiving end of the system (namely the post-stage bus voltage Vo of the photovoltaic array) cannot exceed the allowed maximum value V_maxDiode D blocking, photovoltaic array output power PpvAnd the preset maximum value P of the output power of the photovoltaic array_maxAnd the error obtained after comparison is used as the average value of the input current reference of the laser after PI feedback regulation. When the bus voltage Vo at the receiving end of the system is greater than the allowed maximum value V_maxThe time is that the output power of the photovoltaic array is larger than the sum of the power required by the load and the charging of the storage battery, the output of the PI regulator 2 is a negative value at the time, the diode D is conducted, the output of the PI regulator 2 is used as an adjusting signal to enable the average value i of the current reference injected into the laser to be an average valueDC_refThe output power of the laser is reduced, i.e. decreased, thereby reducing the output power of the photovoltaic array.
On the premise of ensuring that the average output optical power of the laser is constant, the input current pulse width of the laser is gradually reduced, so that the peak power of the laser is increased, the efficiency is increased, but the fluctuation of the output voltage of the photovoltaic array is increased, and the situation that the photovoltaic array deviates from the maximum power point is more serious due to the increase of the fluctuation of the bus voltage at the receiving end of the system, so that the improvement of the efficiency is influenced, and the fluctuation delta V of the output voltage of the photovoltaic array is reducedpvMust be limited to a reasonable rangeInside the enclosure. When the pulse width of the input current of the laser is not reduced to the preset minimum pulse width but the output voltage pulsation of the photovoltaic array exceeds the limit value delta Vpv_maxWhen (as shown in fig. 4 at point a), the energy management optimization strategy switches to the energy management optimization strategy.
The basic control idea of the energy management optimization strategy is as follows: if the pulse width of the LD input current is continuously decreased when the system is supposed to operate at point a shown in fig. 4, as shown at points B and C shown in fig. 4, the output voltage ripple of the photovoltaic array will exceed the limit value, and in order to further improve the overall efficiency of the system while controlling the output voltage ripple of the photovoltaic array, the control strategy will gradually decrease the peak value of the light power to Δ V by sacrificing part of the charging power (but the load power is not changed) of the storage battery under the condition of small pulse width as at points B and Cpv≤ΔVpv_maxPoints D and E as shown in fig. 4 to improve the overall efficiency of the system. Compared with the point D, the pulse width at the point E is smaller, the efficiency is higher, but the same photovoltaic array output voltage pulsation delta V is ensuredpvThe average emitted power of the laser will be smaller, i.e. more charging power is sacrificed. Therefore, for the cases such as point D and point E, the increased efficiency and the sacrificed charging power are balanced by the weighting formula, so as to determine the optimal operating point of the system that satisfies the objectives of high efficiency and fast charging at the same time. The specific weighting formula is as follows:
wherein a and b are weighting coefficients, η*(n) andthe per unit values of the system efficiency and the system charging power at the current moment are specifically as follows:
in formulae (2) and (3), Pin_avg(n)、Ppv_avg(n) the input power of the laser, the output power of the photovoltaic array at the current moment, Pbat(n)、Pbat_maxAnd (n) respectively represent the charging power of the storage battery in the system at the current moment and the set maximum charging power.
In summary, a control flow chart of the energy control strategy based on the efficiency optimization is shown in fig. 5, and the specific implementation method is as follows:
determining whether a control strategy operates or not by judging whether the power required by a load at a receiving end and a storage battery changes or not, setting the pulse width of input current of a laser to be 1 in an initialization stage, namely the input current is a straight continuous current, and setting the current amplitude to be an average current reference i obtained through feedback controlDC_ref；
The output voltage ripple of the photovoltaic array meets the following conditions: Δ Vpv≤ΔVpv_maxThe system works in an efficiency optimal control strategy, and the average output power P of the photovoltaic array is ensuredpv_avgUnder certain conditions, the system efficiency eta is improved by adjusting the pulse width D of the pulse input current of the laser through a disturbance observation method, and in the process, when the system efficiency eta is gradually increased along with the reduction of the pulse width D, the average output power P of the photovoltaic array is ensuredpv_avgConstant, peak value i of laser input currentrefAlso correspondingly increases, resulting in photovoltaic array voltage ripple Δ VpvIncrease, and the greater Δ VpvThe more severe the deviation of the photovoltaic array from the maximum power point is, thereby affecting the improvement of the efficiency, therefore when the delta V is usedpv>ΔVpv_maxWhen the system is switched to the energy management optimization strategy;
when the system enters an energy management optimization strategy, the control strategy will continue to reduce the laser input current pulse width D to search for a working point with better efficiency, in the process, for a certain specific laser input current pulse width D, the control strategy will reduce the peak value of the laser output power, and the photovoltaic array output voltage pulsation is ensured to meet by sacrificing part of the storage battery charging power: Δ Vpv≤ΔVpv_maxAnd meanwhile, the purpose of improving the system efficiency is achieved, and for working points corresponding to different laser input current pulse widths D, the efficiency is often improved along with the reduction of the system charging rapidity, so that for the purpose of ensuring high efficiency and rapid charging, the control strategy compares the working points under the different laser input current pulse widths through a weighting formula (1), and the optimal working point of the system is determined.
One embodiment of the present invention is as follows: taking a laser peak power of 50W and a photovoltaic array peak output power of 1W as an example, fig. 6 shows an experimental result of energy management by a laser wireless power transmission system. The dotted line in the figure is a curve of the system efficiency with the pulse width of the laser input current under the condition that the output voltage pulsation of the photovoltaic array is not considered, namely the system only works under an efficiency optimal control strategy. It can be seen that under the condition of keeping the average output power of the photovoltaic array constant at 0.9W, the system efficiency increases with the decrease of the pulse width, but at the pulse width of 0.45 cycle, the system efficiency increment decreases, which is mainly caused by the fact that the photovoltaic array deviates from the maximum power point more seriously due to the larger output voltage ripple of the photovoltaic array. The solid line in the figure is a plot of system efficiency versus laser input current pulse width for the case where the photovoltaic array output voltage ripple is considered, i.e., the case where the system switches from the efficiency optimized control strategy to the energy management optimized strategy at a pulse width of 0.55 cycles. It can be seen that at the pulse widths of 0.55 and 0.45 cycles, in order to improve the system efficiency and ensure that the output voltage ripple of the photovoltaic array is in a reasonable range, the control strategy correspondingly reduces the output power of the photovoltaic array, and finally, the pulse width of 0.55 cycle is selected as the optimal working point of the system according to the weighting formula.
Claims (6)
1. The energy control method of the laser wireless power transmission system based on efficiency optimization is characterized by comprising the following steps: an efficiency-optimized control strategy and an energy management optimization strategy,
the system is initialized and then operated under an efficiency optimal control strategy, the efficiency optimal control strategy is based on the premise that the output power of the photovoltaic array meets the requirements of loads and storage battery power, the instantaneous emission light power of the laser is changed by adjusting the pulse width and the peak value of the input pulse current of the laser, so that the working points of the laser and the photovoltaic array are adjusted to ensure that the system works at the efficiency optimal point, and the system is switched to an energy management optimization strategy only when the pulse width of the input pulse current of the laser is not reduced to the preset minimum pulse width but the output voltage pulse of the photovoltaic array exceeds the limit value,
the energy management optimization strategy takes the pulse width and the peak value of the input pulse current of the laser as control variables, takes the system efficiency and the system charging power as control targets, further reduces the pulse width of the input pulse current of the laser to search the optimal working point of the system, properly reduces the average output power of the laser in the process of searching the optimal working point of the system to maintain the output voltage pulsation of the photovoltaic array within the limited range, and further enables the system to work at the optimal efficiency point while meeting the rapid charging requirement of the storage battery.
2. The energy control method of the laser wireless power transmission system based on the efficiency optimization as claimed in claim 1, wherein the optimal efficiency control strategy takes photovoltaic array output power, photovoltaic array post-stage bus voltage and laser input pulse current pulse width as control variables, takes system efficiency as a control target, and ensures that the system works at an optimal efficiency point on the premise that the photovoltaic array output power meets the power requirements of a load and a storage battery, specifically:
when the output power of the photovoltaic array does not meet the power requirements of a load and a storage battery, determining the average value of the input current reference of the laser according to the difference value of the output power of the photovoltaic array and the maximum value of the output power of the photovoltaic array, or else, determining the average value of the input current reference of the laser according to the difference value of the output power of the photovoltaic array and the maximum value of the output power of the photovoltaic array and the difference value of the post-stage bus voltage of the photovoltaic array and;
when the system efficiency at the current moment exceeds the system efficiency at the previous moment, the pulse width at the moment when the laser inputs the pulse current is reduced, the peak value at the moment when the laser inputs the pulse current is increased to maintain the output power of the photovoltaic array to be constant,
when the system efficiency at the current moment does not exceed the system efficiency at the previous moment, increasing the pulse width at the moment when the laser inputs pulse current, reducing the peak value at the moment when the laser inputs pulse current to maintain the output power of the photovoltaic array to be constant,
the input power of the laser at the next moment of the laser is sampled to determine the system efficiency at the next moment, the pulse width of the input pulse current of the laser is adjusted in real time according to the system efficiency, and the energy management optimization strategy is switched only when the pulse width of the input pulse current of the laser is not reduced to the preset minimum pulse width but the output voltage pulse of the photovoltaic array exceeds the limit value.
3. The energy control method of the laser wireless power transmission system based on the efficiency optimization according to claim 1 or 2, wherein the energy management optimization strategy takes the pulse width and the peak value of the input pulse current of the laser as control variables, takes the system efficiency and the system charging power as control targets, further reduces the pulse width of the input pulse current of the laser to search for an optimal working point of the system, and properly reduces the average output power of the laser to maintain the output voltage ripple of the photovoltaic array within a limited range during the search for the optimal working point of the system, so as to satisfy the requirement of the rapid charging of the storage battery and enable the system to work at the optimal efficiency point, specifically:
when the weighted value of the system efficiency and the system charging power at the current moment exceeds the maximum value and the system efficiency at the current moment is greater than or equal to the system efficiency corresponding to the maximum output voltage pulsation of the photovoltaic array, taking the weighted value at the current moment as the maximum value, taking the pulse width of the laser input pulse current at the current moment as the optimal value of the pulse width of the laser input pulse current, taking the peak value of the laser input pulse current at the current moment as the optimal value of the peak value of the laser input pulse current, further reducing the pulse width at the moment under the laser input pulse current, and adjusting the peak value at the moment under the laser input pulse current to maintain the output voltage pulsation of the photovoltaic array within the limited range,
when the pulse width at the moment when the laser inputs the pulse current is smaller than the preset minimum pulse width, the optimal values of the pulse width and the peak value of the input pulse current of the laser are fed back to be the optimal working point of the system,
otherwise, sampling the input power of the laser at the next moment of the laser and the output power of the photovoltaic array to determine a weighted value at the next moment, and adjusting the pulse width and the peak value of the input pulse current of the laser in real time according to the weighted value;
when the weighted value of the system efficiency and the system charging power at the current moment does not exceed the maximum value of the weighted value or the system efficiency at the current moment is smaller than the system efficiency corresponding to the maximum output voltage pulsation of the photovoltaic array, the pulse width of the laser at the moment of inputting pulse current is reduced, the peak value of the laser at the moment of inputting pulse current is adjusted to maintain the output voltage pulsation of the photovoltaic array within the limited range, and the optimal control variable is fed back in real time or the input power of the laser and the output power of the photovoltaic array at the next moment of sampling are sampled according to the pulse width of the laser input pulse current.
4. The energy control method of the efficiency optimization-based laser wireless power transmission system according to claim 2, wherein the average value of the laser input current reference is determined according to the difference between the photovoltaic array output power and the maximum value thereof, specifically: and carrying out PI feedback regulation on the difference value of the output power of the photovoltaic array and the maximum value of the output power of the photovoltaic array.
5. The energy control method of the efficiency optimization-based laser wireless power transmission system according to claim 2, wherein the average value of the laser input current reference is determined according to the difference between the output power of the photovoltaic array and the maximum value thereof and the difference between the voltage of the photovoltaic array rear-stage bus and the maximum value thereof, and specifically comprises: and respectively carrying out PI feedback regulation on the difference value between the output power of the photovoltaic array and the maximum value thereof and the difference value between the voltage of the photovoltaic array rear-stage bus and the maximum value thereof to obtain a PI regulation value of the output power deviation of the photovoltaic array and a PI regulation value of the voltage deviation of the photovoltaic array rear-stage bus, and taking the accumulated value of the PI regulation value of the output power deviation of the photovoltaic array and the PI regulation value of the voltage deviation of the photovoltaic array rear-stage bus as the average value of the input current reference of the laser.
6. The energy control method of the laser wireless power transmission system based on efficiency optimization according to claim 3, wherein the weighted values of the system efficiency and the system charging power at the current moment are expressed by the following expression:calculating, J (n) is the weighted value of the system efficiency and the system charging power at the current moment, eta*(n)、Is the per unit value of the system efficiency and the system charging power at the current moment respectively, a and b are the weighting coefficients of the per unit value of the system efficiency and the system charging power at the current moment, Pin_avg(n)、Ppv_avg(n) the input power of the laser, the output power of the photovoltaic array at the current moment, Pbat(n)、Pbat_maxAnd (n) respectively represent the charging power of the storage battery in the system at the current moment and the set maximum charging power.
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