Photovoltaic battery charging method and system

Abstract

The present invention provides a photovoltaic battery charging method and system, which belongs to the field of wireless energy transmission technology, including charging the photovoltaic battery panel by irradiating the photovoltaic battery panel with pulsed laser; setting the steady-state temperature that the photovoltaic battery panel needs to reach according to the required laser irradiation intensity and the heat transfer coefficient of the photovoltaic battery panel; and setting the peak and trough time of the transient pulse laser according to the steady-state temperature, so that the photovoltaic battery panel is cooled down during the trough time period to achieve dynamic control of the temperature of the photovoltaic battery panel. This method can realize dynamic control of the temperature of the photovoltaic cell during unlimited energy transmission, and solves the problem that when the surface temperature of the photovoltaic cell exceeds a certain range, the power output characteristics of the photovoltaic cell are greatly reduced, and the battery is in danger of melting and damage.

Description

Technical Field

[0001] The invention belongs to the technical field of wireless energy transmission, and in particular relates to a photovoltaic cell charging method. Background Art

[0002] Most electronic devices are powered by electricity, so how to transfer energy to related electronic devices is a widely concerned issue. Wireless Power Transfer (WPT) technology breaks away from the original charging method of wire connection and provides a new idea for charging electronic devices. Among them, laser wireless power transmission (LWPT) technology has the advantages of better directional transmission performance, longer transmission distance and better anti-electromagnetic interference. It is widely used in the aerospace field, such as LWPT-driven drones, space solar power stations, distributed laser charging networks, etc.

[0003] Most common LWPT systems use lasers to emit lasers, but lasers with higher energy density can cause the temperature of the photovoltaic cells at the receiving end to rise rapidly. If continuous steady-state high-power charging is used, the laser transmitter will also cause thermal runaway problems due to continuous high energy output. When the surface temperature of the photovoltaic cell exceeds a certain range, the power output characteristics of the photovoltaic cell will be greatly reduced, and there is even a risk of battery melting and damage. Summary of the invention

[0004] In order to overcome the above-mentioned deficiencies in the prior art, the present invention provides a photovoltaic cell charging method.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A photovoltaic battery charging method, comprising:

[0007] Photovoltaic panels are charged by irradiating them with pulsed lasers;

[0008] The steady-state temperature that the photovoltaic panel needs to reach is set according to the required laser irradiation intensity and the heat transfer coefficient of the photovoltaic panel; and the peak and trough time of the transient pulse laser is set according to the steady-state temperature, so that the photovoltaic panel is cooled during the trough period to achieve dynamic control of the photovoltaic panel temperature.

[0009] In order to achieve the cooling effect of photovoltaic cells, it is necessary to keep the peak time of the pulsed laser shorter than the trough time.

[0010] Furthermore, the method for calculating the peak-to-trough time ratio of the transient pulse laser is:

[0011]

[0012] Where G is the laser irradiation intensity received by the photovoltaic cell surface; is the surface temperature of the photovoltaic cell, is the heat transfer coefficient, is the peak time, is the trough time, is the ambient temperature.

[0013] A photovoltaic battery charging system, comprising:

[0014] A pulse laser emission module is used to charge the photovoltaic panel by irradiating the photovoltaic panel with pulse laser;

[0015] The control module is used to set the steady-state temperature that the photovoltaic panel needs to reach according to the required laser irradiation intensity and the heat transfer coefficient of the photovoltaic panel; and set the peak and trough time of the transient pulse laser according to the steady-state temperature, so that the photovoltaic panel is cooled down during the trough period to achieve dynamic control of the temperature of the photovoltaic panel.

[0016] Furthermore, the pulse laser emission module comprises:

[0017] Laser driver module: used to output driving signals;

[0018] The laser is used to generate laser pulses according to the driving signal output by the laser driving module.

[0019] Furthermore, the pulse laser emission module also includes:

[0020] The collimation emission module is used to collimate and focus the laser emitted by the laser.

[0021] Furthermore, it also includes:

[0022] A temperature sensor is used to collect the temperature of the photovoltaic cell surface and then feed it back to the control module;

[0023] The control module is used to adjust the time ratio between the peak and the trough of the pulse laser according to the feedback temperature value.

[0024] Further, the temperature of the photovoltaic cell surface is:

[0025]

[0026] in, is the density, is the heat capacity, The heat source on the photovoltaic cell surface is is the initial temperature of the photovoltaic cell surface, x, y , z They are the three physical directions of photovoltaic cells. The temperature is x, y , z Partial derivatives in three directions, is the partial derivative of temperature with respect to time, indicating the change of temperature over time. is the thermal conductivity of different materials.

[0027] The photovoltaic battery charging method provided by the present invention has the following beneficial effects:

[0028] The present invention proposes a wireless energy transmission scheme for pulsed laser charging, which uses a non-steady-state pulsed laser to charge photovoltaic cells; the peak and trough time of the transient pulsed laser is set in combination with the required laser irradiation intensity and the heat transfer coefficient of the photovoltaic panel, as well as the steady-state temperature to be achieved, so that the photovoltaic cell is cooled down during the trough period to achieve dynamic control of the photovoltaic cell temperature. The problem that when the surface temperature of the photovoltaic cell exceeds a certain range, the power output characteristics of the photovoltaic cell are greatly reduced, and the cell is in danger of melting and damage is solved. At the same time, the use of non-continuous steady-state pulsed laser irradiation can allow the laser emitter to be cooled to a certain extent, avoiding the problem of thermal runaway of the laser emitter due to continuous high energy output. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiment of the present invention and its design scheme, the following briefly introduces the drawings required for this embodiment. The drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 It is a schematic diagram of the method of the present invention;

[0031] Figure 2 is a given pulse time function of an embodiment of the present invention;

[0032] Figure 3 This is the curve of the photovoltaic panel temperature changing with time in different modes. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the scope of protection of the present invention.

[0034] Example:

[0035] In response to the temperature rise problem of photovoltaic cells, a laser irradiation LWPT design scheme based on pulse time control is proposed to solve the problem of steady-state irradiation overheating of photovoltaic cells at the current LWPT receiving end, while improving the irradiation heat density to increase the output power of photovoltaic cells.

[0036] Step 1: For a known photovoltaic panel, use the differential heat conduction equation to calculate its temperature change:

[0037]

[0038] From this we can get: The temperature of the photovoltaic cell surface is:

[0039]

[0040] in, is the density, is the heat capacity, The heat source on the photovoltaic cell surface is is the initial temperature of the photovoltaic cell surface, x, y , z They are the three physical directions of photovoltaic cells. The temperature is x , y , z Partial derivatives in three directions, is the partial derivative of temperature with respect to time, indicating the change of temperature over time. is the thermal conductivity of different materials.

[0041] The surface of the receiving end in contact with the environment adopts the heat flux boundary condition setting, which satisfies the heat convection relationship as shown in the following formula:

[0042]

[0043] in h is the heat transfer coefficient, is the temperature of the battery surface during the actual calculation process.

[0044] Step 2: Given the input heat source size, the peak time of the given laser irradiation is , then assume that the trough time is The estimated photovoltaic cell surface temperature that needs to be controlled is , then the heat conduction equation can be obtained:

[0045]

[0046] The method was calculated with the illumination set to 60 s and the heat transfer coefficient set to According to the relationship, the peak-to-trough time ratio is about 1:2, and the average light intensity is 1600W / m2 So as long as the time ratio of peak to trough is 1:2, the temperature of photovoltaic cells can be controlled in theory. The peak time is selected as 1 s and the trough time is 2s, and the relevant results of pulse irradiation and corresponding steady-state irradiation are calculated.

[0047] The following are specific embodiments:

[0048] like Figure 2 is the pulse time function given by the present invention, such as Figure 3 This is the curve of the photovoltaic panel temperature changing with time in different modes.

[0049] The initial light intensity of the pulse irradiation is 3000W / m 2 After 1 km of attenuation, the average radiation intensity reaching the surface of the photovoltaic cell is 1600W / m 2 The calculation shows that the photovoltaic cell reaches a dynamic equilibrium when the temperature rises to about 315 K. For comparison, the irradiance of 3000W / m 2 The steady-state laser ensures the same output power and finds that the temperature of the photovoltaic cell is much higher than that of the pulse irradiation; keeping the same received energy, the light intensity becomes the original ,At this time, although the temperature is roughly the same as the pulse mode, the output power is less than the pulse mode.

[0050] The embodiments described above are only preferred specific implementation modes of the present invention, and the protection scope of the present invention is not limited thereto. Any simple changes or equivalent replacements of the technical solutions that can be obviously obtained by any technician familiar with the field within the technical scope disclosed in the present invention belong to the protection scope of the present invention.

Claims

1. A photovoltaic battery charging method, characterized in that: include: Photovoltaic panels are charged by irradiating them with pulsed lasers; According to the required laser irradiation intensity and the heat transfer coefficient of the photovoltaic panel, the steady-state temperature that the photovoltaic panel needs to reach is given; and the peak and trough time of the transient pulse laser is set according to the steady-state temperature, so that the photovoltaic panel is cooled down during the trough period to achieve dynamic control of the temperature of the photovoltaic panel; The peak time of the pulse laser is shorter than the trough time; The method of the peak-to-trough time ratio of the transient pulse laser is: ； Where G is the laser irradiation intensity received by the photovoltaic cell surface; is the surface temperature of the photovoltaic cell, is the heat transfer coefficient, is the peak time, is the trough time, is the ambient temperature.

2. A photovoltaic battery charging system using the method as claimed in claim 1, characterized in that: include: A pulse laser emission module is used to charge the photovoltaic panel by irradiating the photovoltaic panel with pulse laser; The control module is used to set the steady-state temperature that the photovoltaic panel needs to reach according to the required laser irradiation intensity and the heat transfer coefficient of the photovoltaic panel; and set the peak and trough time of the transient pulse laser according to the steady-state temperature, so that the photovoltaic panel is cooled down during the trough period to achieve dynamic control of the temperature of the photovoltaic panel.

3. A photovoltaic battery charging system according to claim 2, characterized in that: The pulse laser emission module comprises: Laser driving module, used for outputting driving signals; The laser is used to generate laser pulses according to the driving signal output by the laser driving module.

4. A photovoltaic battery charging system according to claim 3, characterized in that: The pulse laser emission module also includes: The collimation emission module is used to collimate and focus the laser emitted by the laser.

5. A photovoltaic battery charging system according to claim 2, characterized in that: Also includes: A temperature sensor is used to collect the temperature of the photovoltaic cell surface and then feed it back to the control module; The control module is used to adjust the time ratio between the peak and the trough of the pulse laser according to the feedback temperature value.

6. A photovoltaic battery charging system according to claim 5, characterized in that: The temperature of the photovoltaic cell surface is: ； in, is the density, is the heat capacity of the corresponding material, The heat source on the photovoltaic cell surface is is the initial temperature of the photovoltaic cell surface, x, y , z They are the three physical directions of photovoltaic cells. The temperature is x , y , z Partial derivatives in three directions, It is the partial derivative of temperature with respect to time, indicating the change of temperature with time.

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