Inverter and speed regulation method for its cooling fan, and photovoltaic system

Abstract

The application provides a kind of inverter and its speed regulation method of heat dissipation fan, and photovoltaic system, inverter includes controller, power module, input port and output port, temperature detection device and at least one heat dissipation fan.Wherein, temperature detection device is used to detect the first temperature when power module outputs first signal and the second temperature when power module outputs second signal, the detection time of the first temperature is before the detection time of the second temperature.Further, controller is used to: according to the variation between second signal, first signal and second signal, second temperature and the variation between first temperature and second temperature, target fan duty cycle is adjusted, to quickly control the rotating speed of each heat dissipation fan in at least one heat dissipation fan, so that the temperature cycle number and temperature cycle amplitude of power module can be reduced, effectively inhibit the temperature cycle of power module, improve the safety and reliability of power module, and have strong applicability.

Description

[0001] This application is a divisional application. The original application has the application number 202210645675.6 and the original application date is June 9, 2022. The entire contents of the original application are incorporated herein by reference. Technical Field

[0002] This application relates to the field of electronic power technology, and in particular to an inverter and a method for regulating the speed of its cooling fan, as well as a photovoltaic system. Background Technology

[0003] To ensure the safe and reliable operation of the inverter, the fans in the inverter cool the heat generated by the power modules, keeping the power module temperature below the safe allowable junction temperature, thus ensuring normal operation of the power modules. During the heat dissipation process, the fan speed is adjusted to suppress temperature cycling within the power modules, thereby improving the safety and reliability of the power modules.

[0004] In existing technologies, the start-stop temperature points of the fans are adjusted according to the inverter's operating status to dynamically fit the fan speed curve. The fan speed is then adjusted based on this curve to rapidly cool the power module, thereby ensuring its safe operation. However, in cases of sudden power fluctuations (or frequent power changes) in the inverter, the fans frequently start and stop, increasing the number and amplitude of temperature cycles in the power module. This makes it difficult to effectively suppress temperature cycling in the power module, resulting in poor safety and applicability. Summary of the Invention

[0005] This application provides an inverter and its cooling fan speed regulation method, as well as a photovoltaic system, which can reduce the number of temperature cycles and the temperature cycle amplitude of the power module, effectively suppress the temperature cycle of the power module, thereby improving the safety and reliability of the power module and having strong applicability.

[0006] Firstly, this application provides an inverter comprising a controller, a power module, input ports and output ports, a temperature detection device, and at least one cooling fan. The power module and the at least one cooling fan constitute a heat dissipation system in the inverter, wherein the at least one cooling fan refers to one or more cooling fans. The input ports are used to receive DC input signals, and the output ports are used to output a first signal and a second signal. The power module is used to perform AC-DC conversion on the DC input signal to output the first signal or the second signal, wherein each of the first and second signals may include, but is not limited to, output power or output current. The temperature detection device is used to detect a first temperature when the power module outputs the first signal and a second temperature when the power module outputs the second signal, thereby ensuring the real-time performance and accuracy of temperature sampling. The detection time of the first temperature is before the detection time of the second temperature. Further, the controller is used to adjust the duty cycle of the target fan according to the second signal, the change between the first and second signals, the second temperature, and the change between the first and second temperatures, to control the rotational speed of each of the at least one cooling fan. The cooling fans then operate at their respective rotational speeds to dissipate heat from the power module.

[0007] In this application, since the first signal, the second signal, the first temperature, and the second temperature are all real-time detection data, that is, the changes between the first signal and the second signal, and the changes between the first temperature and the second temperature are real-time changes, the controller can dynamically adjust the duty cycle of the target fan according to the real-time detection data and the real-time changes to quickly control the speed of each cooling fan. This can reduce the number of temperature cycles and the amplitude of temperature cycles in the power module, effectively suppressing the temperature cycle of the power module and thus improving the safety of the power module. In addition, it also reduces the lifespan loss of the power module and improves the reliability of the power module, making it highly applicable.

[0008] In conjunction with the first aspect, in a first possible implementation, the inverter further includes a power board and a heat sink, wherein the power board is used to carry the power module, and the heat sink is used to dissipate heat from the power module. The first or second temperature includes: the temperature of the power module, the internal air temperature of the inverter, the temperature of the power board, or the temperature of the heat sink.

[0009] In conjunction with the first aspect or the first possible implementation of the first aspect, in the second possible implementation, the change between the first signal and the second signal includes at least one of the difference between the first signal and the second signal, the rate of change, the direction of change, and the time difference. The change between the first temperature and the second temperature includes at least one of the difference between the first temperature and the second temperature, the rate of change, the direction of change, and the detection time difference.

[0010] In a third possible implementation, combining any of the first to second possible embodiments of the first aspect, during the adjustment of the target fan duty cycle, the controller is used to obtain a first duty cycle parameter based on a second temperature and a second signal, wherein the first duty cycle parameter is a steady-state adjustment amount reflecting the fan speed. The controller can also obtain a second duty cycle parameter based on the change between the first and second signals, and a third duty cycle parameter based on the change between the first and second temperatures. The second duty cycle parameter, reflecting a dynamic adjustment amount reflecting the fan speed, can reduce the impact of sudden changes in illumination and load on the temperature cycle number and amplitude of the power module, thereby reducing the temperature cycle number and amplitude of the power module. The third duty cycle parameter, reflecting a dynamic adjustment amount reflecting the fan speed, can reduce the impact of the cooling fan's start / stop and ambient temperature on the temperature cycle number and amplitude of the power module, thereby reducing the temperature cycle amplitude of the power module in power fluctuation scenarios, i.e., avoiding large fluctuations in the temperature cycle amplitude of the power module in power fluctuation scenarios.

[0011] Furthermore, the controller can also adjust the target fan duty cycle based on the first duty cycle parameter, the second duty cycle parameter, and the third duty cycle parameter. Since the first duty cycle parameter reflects the steady-state adjustment of the fan speed, and the second and third duty cycle parameters reflect the dynamic adjustment of the fan speed, the target fan duty cycle can simultaneously reflect both the steady-state and dynamic adjustment of the fan speed. This improves the accuracy of the target fan duty cycle, reduces the number of temperature cycles and the amplitude of temperature cycles in the power module, effectively suppresses temperature cycling in the power module, and thus improves the safety of the power module.

[0012] In conjunction with the third possible implementation of the first aspect, in the fourth possible implementation, the controller is used to obtain the weighting coefficients of each duty cycle parameter among the first, second, and third duty cycle parameters, and adjust the target fan duty cycle based on each duty cycle parameter and its weighting coefficients. The weighting coefficients are greater than or equal to 0 and less than or equal to 1, and these weighting coefficients can be preset parameters set at the inverter's factory, parameters set by the user, or parameters dynamically adjusted according to the specific operating conditions of the inverter. It can be understood that the controller achieves flexible control of the proportions of each duty cycle parameter through the weighting coefficients, thereby reducing the number of temperature cycles and the temperature cycle amplitude of the power module, and improving the safety of the power module.

[0013] In a fifth possible implementation, combining any one of the first to fourth possible embodiments, after adjusting the target fan duty cycle, the controller controls a portion of at least one cooling fan to rotate at 0 speed and another portion to rotate at a first speed when the target fan duty cycle is less than a preset duty cycle threshold. The number of the other portion of cooling fans and the first speed are determined by a second temperature and a second signal, and the first speed is less than the preset speed threshold. Furthermore, the number of the other portion of cooling fans can be understood as the number of operating cooling fans, and the first speed can be understood as the operating speed of the cooling fans. The preset speed threshold here refers to the maximum speed value of the cooling fans operating in the low-speed range. When the speed of one portion of cooling fans is 0, it can be concluded that some cooling fans are not operating; when the speed of another portion of cooling fans is the first speed, it can be concluded that the other portion of cooling fans are operating in the low-speed range. It is understandable that when the target fan duty cycle is less than the preset duty cycle threshold, the controller will flexibly control the number and speed of the cooling fans in the low-speed range, which can expand the heat dissipation efficiency range of the cooling system in the inverter, thereby effectively suppressing the temperature cycle number of the power module and significantly reducing the inverter's losses, making it more versatile.

[0014] The controller described above is also used to control the speed of at least one cooling fan to a second speed based on the target fan duty cycle when the target fan duty cycle is greater than or equal to a preset duty cycle threshold. The second speed is greater than the first speed, and the second speed refers to any speed value at which the cooling fan operates at high speed. It can be understood that when the target fan duty cycle is greater than or equal to the preset duty cycle threshold, the controller will control all cooling fans to operate simultaneously to quickly dissipate heat from the power module, thereby improving the inverter's heat dissipation efficiency and offering broad applicability. In summary, the controller can compare the target fan duty cycle with the preset duty cycle threshold and flexibly control at least one cooling fan to operate at low or high speed based on the comparison result, thereby widening the operating range of the cooling system to improve heat dissipation efficiency and enhancing its applicability.

[0015] Secondly, this application provides a speed control method for an inverter cooling fan. This method is applicable to the controller in an inverter, which also includes a power module and at least one cooling fan. In this method, the controller can detect a first temperature when the power module outputs a first signal and a second temperature when the power module outputs a second signal, thereby ensuring the real-time performance and accuracy of temperature sampling. Each of the first and second signals may include, but is not limited to, output power or output current, and the detection time of the first temperature precedes the detection time of the second temperature. Further, the controller can adjust the duty cycle of the target fan based on the second signal, the change between the first and second signals, the second temperature, and the change between the first and second temperatures, to control the rotational speed of each cooling fan in the at least one cooling fan.

[0016] In this application, since the first signal, the second signal, the first temperature, and the second temperature are all real-time detection data, that is, the changes between the first signal and the second signal, and the changes between the first temperature and the second temperature are real-time changes, the controller can dynamically adjust the duty cycle of the target fan according to the real-time detection data and the real-time changes to quickly control the speed of each cooling fan. This can reduce the number of temperature cycles and the amplitude of temperature cycles in the power module, effectively suppressing the temperature cycle of the power module and thus improving the safety of the power module. In addition, it also reduces the lifespan loss of the power module and improves the reliability of the power module, making it highly applicable.

[0017] In conjunction with the second aspect, in a first possible implementation, the inverter further includes a power board and a heat sink, wherein the power board carries the power module, and the heat sink dissipates heat from the power module. The first or second temperature includes: the temperature of the power module, the internal air temperature of the inverter, the temperature of the power board, or the temperature of the heat sink.

[0018] In conjunction with the second aspect or the first possible implementation of the second aspect, in the second possible implementation, the change between the first signal and the second signal includes at least one of the difference between the first signal and the second signal, the rate of change, the direction of change, and the time difference. The change between the first temperature and the second temperature includes at least one of the difference between the first temperature and the second temperature, the rate of change, the direction of change, and the detection time difference.

[0019] In a third possible implementation, in conjunction with any of the second aspects to the second possible implementations, during the adjustment of the target fan duty cycle, the controller is used to obtain a first duty cycle parameter based on a second temperature and a second signal, wherein the first duty cycle parameter is a steady-state adjustment amount reflecting the fan speed. The controller can also obtain a second duty cycle parameter based on the change between the first and second signals, and a third duty cycle parameter based on the change between the first and second temperatures. The second duty cycle parameter, reflecting a dynamic adjustment amount reflecting the fan speed, can reduce the impact of sudden changes in illumination and load on the temperature cycle number and amplitude of the power module, thereby reducing the temperature cycle number and amplitude of the power module. The third duty cycle parameter, also reflecting a dynamic adjustment amount reflecting the fan speed, can reduce the impact of the cooling fan's start / stop and ambient temperature on the temperature cycle number and amplitude of the power module, thereby reducing the temperature cycle amplitude of the power module in power fluctuation scenarios, i.e., avoiding large fluctuations in the temperature cycle amplitude of the power module in power fluctuation scenarios.

[0020] Furthermore, the controller can also adjust the target fan duty cycle based on the first duty cycle parameter, the second duty cycle parameter, and the third duty cycle parameter. Since the first duty cycle parameter reflects the steady-state adjustment of the fan speed, and the second and third duty cycle parameters reflect the dynamic adjustment of the fan speed, the target fan duty cycle can simultaneously reflect both the steady-state and dynamic adjustment of the fan speed. This improves the accuracy of the target fan duty cycle, reduces the number of temperature cycles and the amplitude of temperature cycles in the power module, effectively suppresses temperature cycling in the power module, and thus improves the safety of the power module.

[0021] In conjunction with the third possible implementation of the second aspect, in the fourth possible implementation, the controller can obtain the weighting coefficients of each duty cycle parameter among the first, second, and third duty cycle parameters, and adjust the target fan duty cycle based on each duty cycle parameter and its weighting coefficients. The weighting coefficient of any duty cycle parameter is greater than or equal to 0 and less than or equal to 1. This weighting coefficient can be a preset parameter set by the inverter at the factory, a parameter set by the user, or a parameter dynamically adjusted according to the specific operating conditions of the inverter. It can be understood that the controller achieves flexible control of the proportions of each duty cycle parameter through weighting coefficients, thereby reducing the number of temperature cycles and the temperature cycle amplitude of the power module, and improving the safety of the power module.

[0022] In a fifth possible implementation, combining any of the second to fourth possible embodiments, after adjusting the target fan duty cycle, the controller, when the target fan duty cycle is less than a preset duty cycle threshold, controls a portion of the at least one cooling fan to rotate at 0 speed and another portion to rotate at a first speed. The number of the other portion of cooling fans and the first speed are determined by a second temperature and a second signal, and the first speed is less than the preset speed threshold. Furthermore, the number of the other portion of cooling fans can be understood as the number of operating cooling fans, and the first speed can be understood as the operating speed of the cooling fans. The preset speed threshold here refers to the maximum speed value of the cooling fans operating in the low-speed range. When the speed of a portion of the cooling fans is 0, it can be concluded that a portion of the cooling fans are not operating; when the speed of another portion of the cooling fans is the first speed, it can be concluded that the other portion of the cooling fans are operating in the low-speed range. It is understandable that when the duty cycle of the target fan is less than the preset duty cycle threshold, the controller will flexibly control the number and speed of the cooling fans in the low-speed range. For example, by flexibly controlling different combinations of the number of fans and different combinations of the speed, the heat dissipation efficiency range of the cooling system in the inverter can be expanded, that is, the equivalent efficiency adjustment range of the cooling system is improved, thereby effectively suppressing the temperature cycle number of the power module and significantly reducing the inverter's losses, making it more applicable.

[0023] The controller described above can also control the speed of at least one cooling fan to a second speed based on the target fan duty cycle when the target fan duty cycle is greater than or equal to a preset duty cycle threshold. The second speed is greater than the first speed, and refers to any speed value at which the cooling fan operates at high speed. It can be understood that when the target fan duty cycle is greater than or equal to the preset duty cycle threshold, the controller will control all cooling fans to operate simultaneously to quickly dissipate heat from the power module, thereby improving the inverter's heat dissipation efficiency and offering broad applicability. In summary, the controller can compare the target fan duty cycle with the preset duty cycle threshold and flexibly control at least one cooling fan to operate at low or high speed based on the comparison result, thus widening the operating range of the cooling system to improve heat dissipation efficiency and enhancing its applicability.

[0024] Thirdly, this application provides a photovoltaic system including a photovoltaic array and an inverter connected to the photovoltaic array as provided in any of the first to fifth possible embodiments described above. The output of the inverter can be connected to an AC power grid, wherein the connection includes direct or indirect connection. During the process of supplying power to the AC power grid, the inverter can convert the DC voltage provided by the photovoltaic array into AC voltage and supply power to the AC power grid based on the AC voltage. When the inverter includes a cooling system and a controller, the controller can monitor the health status of the cooling system in real time to ensure reliable operation of the inverter. Therefore, the power supply reliability and security of the aforementioned inverter are higher, thereby improving the power supply efficiency and security of the photovoltaic system and enhancing its adaptability.

[0025] In conjunction with the third aspect, in the first possible implementation, the photovoltaic system further includes a DC combiner box. The photovoltaic array can be connected to the input terminal of the inverter via the DC combiner box, and the output terminal of the inverter can be connected (e.g., directly or indirectly) to the AC power grid. During the process of supplying power to the AC power grid, the DC combiner box can combine the DC voltages provided by each photovoltaic string in the photovoltaic array and output them to the inverter. At this time, the inverter (e.g., a centralized photovoltaic inverter) can supply power to the AC power grid based on the combined DC voltage. During this power supply process, because the inverter has higher power supply reliability and security, the power supply efficiency and security of the photovoltaic system can be improved, and its adaptability is stronger.

[0026] In conjunction with the first possible implementation of the third aspect, in the second possible implementation, the photovoltaic system further includes a box-type transformer, through which the output of the inverter can be connected to the AC power grid. During the supply of power to the AC power grid, the DC combiner box can combine the DC voltages provided by each photovoltaic string in the photovoltaic array and output them to the inverter. At this time, the inverter (such as a centralized photovoltaic inverter) can supply power to the AC power grid based on the combined DC voltage. During this power supply process, because the inverter has higher power supply reliability and security, the power supply efficiency and security of the photovoltaic system can be improved, and its adaptability is stronger.

[0027] In conjunction with the third aspect, in a third possible implementation, the photovoltaic system further includes an AC combiner box. The photovoltaic array can be connected to the input of the AC combiner box via an inverter, and the output of the AC combiner box can be connected (e.g., directly or indirectly) to the AC power grid. During the supply of power to the AC power grid, the inverter can provide AC voltage to the AC combiner box based on the DC voltage provided by the photovoltaic array. The AC combiner box can supply power to the AC power grid using the AC voltage input to the inverter (e.g., a string photovoltaic inverter). In this power supply process, because the inverter offers higher power supply reliability and security, the power supply efficiency and security of the photovoltaic system can be improved, resulting in greater adaptability.

[0028] In conjunction with the third possible implementation method of the third aspect, in the fourth possible implementation method, the photovoltaic system further includes a box-type transformer, and the output terminal of the AC combiner box can be connected to the AC power grid through the box-type transformer. During the process of supplying power to the AC power grid, the AC combiner box can combine the AC voltage input to the inverter (such as a string photovoltaic inverter) and output it to the box-type transformer. At this time, the box-type transformer can supply power to the AC power grid based on the combined AC voltage. During this power supply process, because the power supply reliability and security of the inverter are higher, the power supply efficiency and security of the photovoltaic system can be improved, and its adaptability is stronger.

[0029] In conjunction with the third aspect, in the fifth possible implementation, the photovoltaic system further includes a direct current (DC) / DC converter and a DC bus. The photovoltaic array can be connected to the input of an inverter via the DC / DC converter and the DC bus, and the output of the inverter can be connected to the AC power grid. During the supply of power to the AC power grid, the DC / DC converter can convert the DC voltage provided by the photovoltaic array into a target DC voltage and output the target DC voltage to the inverter via the DC bus. The inverter can then convert the target DC voltage into an AC voltage and supply power to the AC power grid based on this AC voltage. In this power supply process, because the inverter offers higher power supply reliability and security, the power supply efficiency and security of the photovoltaic system can be improved, and its adaptability is enhanced.

[0030] In this application, the controller can dynamically adjust the duty cycle of the target fan based on the second signal, the change between the first and second signals, the second temperature, and the change between the first and second temperatures. This allows for rapid control of the speed of each cooling fan, reducing the number and amplitude of temperature cycles in the power module, thereby improving the safety of the power module. Furthermore, it reduces the lifespan loss of the power module and improves its reliability. Further, the controller can compare the target fan duty cycle with a preset duty cycle threshold and flexibly control at least one cooling fan to operate at low or high speed based on the comparison result. This broadens the operating range of the cooling system, improving heat dissipation efficiency and enhancing its applicability. Attached Figure Description

[0031] Figure 1 This is a schematic diagram illustrating the application scenario of the inverter provided in this application;

[0032] Figure 2 This is a structural schematic diagram of the inverter provided in this application;

[0033] Figure 3A This is a schematic diagram illustrating the effect of suppressing temperature cycling in the power module provided in this application;

[0034] Figure 3B This is another schematic diagram illustrating the effect of suppressing temperature cycling of the power module provided in this application;

[0035] Figure 4 This is another structural schematic diagram of the inverter provided in this application;

[0036] Figure 5 This is a structural schematic diagram of the photovoltaic system provided in this application;

[0037] Figure 6 This is another structural schematic diagram of the photovoltaic system provided in this application;

[0038] Figure 7 This is another structural schematic diagram of the photovoltaic system provided in this application;

[0039] Figure 8 This is another structural schematic diagram of the photovoltaic system provided in this application;

[0040] Figure 9 This is a flowchart illustrating the speed control method for the inverter cooling fan provided in this application;

[0041] Figure 10 This is another flowchart illustrating the speed control method for the inverter cooling fan provided in this application. Detailed Implementation

[0042] The inverter (an AC / DC converter) provided in this application is applicable to various fields, including new energy smart microgrids, power transmission and distribution, new energy (such as photovoltaic grid connection or wind power grid connection), photovoltaic power generation (such as photovoltaic inverters), wind power generation, high-power converters (such as converting DC voltage to high-power high-voltage AC), and electric equipment (such as various electric equipment). The specific application can be determined according to the actual application scenario, and no restrictions are imposed here.

[0043] The inverter provided in this application is adaptable to both high-power and low-to-medium power inverter applications, such as photovoltaic power supply, wind power grid-connected power supply, electric vehicle charging, and other applications. The following explanation will use a photovoltaic power supply application as an example; further details will not be provided here. Please refer to [link to relevant documentation]. Figure 1 , Figure 1 This is a schematic diagram illustrating the application scenario of the inverter provided in this application. For example... Figure 1As shown, the photovoltaic system includes a photovoltaic array, a DC / DC converter, a positive DC bus, a negative DC bus, and an inverter. The photovoltaic array can be connected to the input of the DC / DC converter. The output of the DC / DC converter can be connected to the input of the inverter via the positive and negative DC buses. The output of the inverter can be used to connect to the power grid. The photovoltaic array can be composed of multiple photovoltaic strings connected in series and parallel. Each photovoltaic string can include multiple photovoltaic modules (also called solar panels). The inverter includes a power module and n cooling fans. During the process of the photovoltaic system supplying power to the AC grid, the DC / DC converter can output a target DC voltage to the inverter based on the DC voltage provided by the photovoltaic array. At this time, the power module in the inverter can perform AC-DC conversion on the target DC voltage, thereby outputting an AC voltage to supply power to the AC grid.

[0044] During this power supply process, precise control of the rotational speeds of the n cooling fans is crucial as they dissipate heat generated by the power module. In controlling the fan speeds, the inverter's controller (not shown in the diagram) detects the first temperature when the power module outputs a first signal and the second temperature when it outputs a second signal. Each of the first and second signals includes either output power or output current, and the first temperature is detected before the second temperature. Furthermore, the controller adjusts the target fan duty cycle based on the changes between the second, first, and second signals, as well as the changes between the first and second temperatures, to quickly control the rotational speeds of each of the n cooling fans. This reduces the number of temperature cycles (also known as temperature fluctuations) and the temperature cycle amplitude of the power module, effectively suppressing temperature cycling and improving its safety and reliability. This further enhances the inverter's power supply reliability and safety, making it highly adaptable.

[0045] The following will combine Figures 2 to 8 This application provides illustrative examples of the inverter, photovoltaic system, and their working principles.

[0046] See Figure 2 , Figure 2 This is a structural schematic diagram of the inverter provided in this application. Figure 2 As shown, inverter 1 includes a controller 10, a power module 11, an input port 12 and an output port 13, a temperature detection device 14, and at least one cooling fan (i.e., one or more cooling fans, such as cooling fans 15a to 15n). The power module 11 and cooling fans 15a to 15n constitute the heat dissipation system in inverter 1. The input port 12 is used to receive a DC input signal; for example, this DC input signal can be generated by... Figure 1The photovoltaic array in the power module 11 provides the signal. The output port is used to output a first signal and a second signal, which can be provided by the power module 11.

[0047] In some feasible implementations, power module 11 refers to a functional module that integrates the core power electronic switching devices (such as semiconductor switching devices) inside inverter 1. These semiconductor switching devices include, but are not limited to, insulated-gate bipolar transistors (IGBTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), and other types of switching devices. Furthermore, these semiconductor switching devices can be made of silicon semiconductor material Si, or third-generation wide-bandgap semiconductor materials such as silicon carbide (SiC), gallium nitride (GaN), diamond, zinc oxide (ZnO), or other materials. The specific type of switching device can be determined by the actual circuit topology and actual operating requirements of inverter 1, and is not limited here. Power module 11 can perform AC-DC conversion on the DC input signal to output a first signal or a second signal. Each of the first signal and the second signal includes, but is not limited to, output power or output current. The first signal and the second signal can be understood as the output signal of the power module 11.

[0048] In some feasible implementations, the temperature detection device 14 may be located outside the controller 10; alternatively, the temperature detection device 14 may also be located inside the controller 10. The temperature detection device 14 includes, but is not limited to, at least one of the following temperature-sensitive devices: a thermocouple, a positive temperature coefficient (PTC) thermistor, a negative temperature coefficient (NTC) thermistor, a silicon resistance temperature sensor, and an IC temperature sensor. A positive temperature coefficient thermistor may be simply referred to as a PTC thermistor, and a negative temperature coefficient thermistor may be simply referred to as an NTC thermistor.

[0049] In some feasible implementations, the temperature detection device 14 can detect a first temperature when the power module 11 outputs a first signal and a second temperature when the power module 11 outputs a second signal, thereby ensuring the real-time performance and accuracy of temperature detection. The detection time of the first temperature is before the detection time of the second temperature. In one embodiment, the inverter 1 further includes a power board and a heat sink. The power board is used to support the power module 11, and the heat sink is used to dissipate heat from the power module 11. Figure 2 The first temperature or second temperature mentioned above can be understood as the temperature of the power module 11, and the first temperature or second temperature includes, but is not limited to: the temperature of the power module 11, the internal air temperature of the inverter 1, the temperature of the power board, or the temperature of the heat sink. The temperature detection device 14 mentioned above can establish wired or wireless communication with the controller 10 to transmit temperature data. For example, the temperature data includes the first temperature and the second temperature. For ease of description, the following will be described using the example of the first temperature or second temperature including the temperature of the power module 11, and will not be repeated hereafter. At this time, the second signal is the current output signal of the power module 11, and the second temperature is the current temperature of the power module 11.

[0050] In some feasible implementations, the controller 10 adjusts the duty cycle of the target fan based on the second signal, the change between the first and second signals, and the change between the first and second temperatures, to control the rotational speed of each cooling fan from cooling fans 15a to cooling fans 15n. At this time, each cooling fan operates at its respective rotational speed to dissipate heat from the power module 11. Since the first signal, the second signal, the first temperature, and the second temperature are all real-time detected data—that is, the change between the first and second signals and the change between the first and second temperatures are real-time changes—the controller 10 can dynamically adjust the duty cycle of the target fan based on the real-time detected data and the real-time changes to quickly control the rotational speed of each cooling fan. This reduces the number and amplitude of temperature cycles in the power module, effectively suppressing temperature cycling and thus improving the safety of the power module. Furthermore, it reduces the lifespan loss of the power module and improves its reliability, making it highly adaptable. Here, temperature cycling can be understood as the environmental temperature cycling of the inverter 1 at different time scales in different natural environments.

[0051] In some feasible implementations, the change between the first temperature and the second temperature includes at least one of the following: the difference between the first temperature and the second temperature, the rate of change, the direction of change, and the time difference. The rate of change is the ratio between the difference between the first temperature and the second temperature and the detection time difference. The direction of change is the temperature change trend of the power module 11, which can be either positively increasing or negatively decreasing. The detection time difference is the difference between the detection time of the first temperature and the detection time of the second temperature, and this detection time difference is greater than 0. When the first temperature is greater than the second temperature, the difference between the first temperature and the second temperature and the rate of change are less than 0, and the direction of change between the first temperature and the second temperature is negatively decreasing, meaning the temperature change trend of the power module 11 is negatively decreasing. When the first temperature is less than the second temperature, the difference between the first temperature and the second temperature and the rate of change are greater than 0, and the direction of change between the first temperature and the second temperature is positively increasing, meaning the temperature change trend of the power module 11 is positively increasing.

[0052] In some feasible implementations, the change between the first signal and the second signal includes, but is not limited to, at least one of the following: the difference between the first signal and the second signal, the rate of change, the direction of change, and the time difference. The rate of change is the ratio between the difference between the first signal and the second signal and the time difference. The direction of change is the output change trend of the power module 11, which includes a positive increase or a negative decrease. When each of the first and second signals is output power, the output change trend of the power module 11 is a power change trend; when each of the first and second signals is output current, the output change trend of the power module 11 is a current change trend. The time difference is the difference between the detection time of the first signal and the detection time of the second signal, and the time difference is greater than 0. When the first signal is greater than the second signal, the difference and rate of change between the first and second signals are less than 0, and the direction of change between the first and second signals is a negative decrease, i.e., the output change trend of the power module 11 is a negative decrease. When the first signal is less than the second signal, the difference and rate of change between the first and second signals are greater than 0, and the direction of change between the first signal and the second signal is a positive increase, i.e., the output change trend of the power module 11 is a positive increase.

[0053] In some feasible implementations, the controller 10 can detect the operating status of the inverter 1 in real time. The real-time detection of the operating status of the inverter 1 includes: detecting the first signal and the second signal output by the power module 11 through the output port 13, and detecting the first temperature when the power module 11 outputs the first signal and the second temperature when the power module 11 outputs the second signal from the temperature detection device 14. This ensures the accuracy and real-time performance of temperature detection and output signal detection, and has strong applicability.

[0054] In some feasible implementations, after detecting the operating state of inverter 1, controller 10 can obtain a first duty cycle parameter d1 based on a second signal and a second temperature. The first duty cycle parameter d1 can be understood as a fan speed control quantity, and it reflects the steady-state adjustment of the fan speed. Specifically, controller 10 outputs the first duty cycle parameter d1 based on the monotonic mapping relationship between the second temperature, the second signal, and the fan speed; that is, the input parameters of the monotonic mapping relationship are the second temperature and the second signal, and the output parameter is the first duty cycle parameter d1. The implementation of this monotonic mapping relationship includes, but is not limited to, functions, formulas, graphs, or curves; and this monotonic mapping relationship can be expressed as follows: when the temperature of power module 11 increases or the output signal of power module 11 increases, the first duty cycle parameter d1 increases; when the temperature of power module 11 decreases or the output signal of power module 11 decreases, the first duty cycle parameter d1 decreases.

[0055] Optionally, the controller 10 can also obtain a first duty cycle parameter d based on the second signal. 11 And based on the second temperature, another first duty cycle parameter d is obtained. 12 Among them, the first duty cycle parameter d 11 and the first duty cycle parameter d 12 This can be understood as the fan speed control variable, and the first duty cycle parameter d 11 To reflect the steady-state adjustment of the fan speed associated with the second signal, the first duty cycle parameter d 12 This reflects the steady-state adjustment of the fan speed in relation to the second temperature. For ease of description, the first duty cycle parameter d1 will be used as an example below, and will not be elaborated further.

[0056] In some feasible implementations, the controller 10 obtains a second duty cycle parameter d2 based on the change between the first and second signals, and a third duty cycle parameter d3 based on the change between the first and second temperatures. The second duty cycle parameter d2 can be understood as a fan speed control quantity, reflecting a dynamic adjustment of the fan speed. This reduces the impact of sudden changes in illumination and load on the temperature cycle number and amplitude of the power module 11, thereby reducing the temperature cycle number and amplitude of the power module 11 and effectively suppressing temperature cycling. Similarly, the third duty cycle parameter d3 can also be understood as a fan speed control quantity, reflecting a dynamic adjustment of the fan speed. This reduces the impact of the cooling fan's start / stop and ambient temperature on the temperature cycle number and amplitude of the power module 11, thereby reducing the temperature cycle amplitude of the power module 11 under power fluctuation scenarios, thus preventing large fluctuations in the temperature cycle amplitude of the power module 11 under power fluctuation scenarios.

[0057] Specifically, the controller 10 can also output a second duty cycle parameter d2 based on the monotonic mapping relationship between the change between the first and second signals and the fan speed. That is, the input parameter of the monotonic mapping relationship is the change between the first and second signals, and the output parameter is the second duty cycle parameter d2. The implementation of the monotonic mapping relationship can include, but is not limited to, functions, formulas, graphs, or curves. Furthermore, this monotonic mapping relationship can be expressed as follows: when the output of the power module 11 shows a positive increasing trend, the second duty cycle parameter d2 increases; when the output of the power module 11 shows a negative decreasing trend, the second duty cycle parameter d2 decreases. For example, when the monotonic mapping relationship is a differential formula, the second duty cycle parameter d2 is the value obtained by differentiating the change between the first and second signals. It should be noted that the specific implementation of this monotonic mapping relationship can be determined according to the actual application scenario and is not limited here.

[0058] Furthermore, the controller 10 can also output a third duty cycle parameter d3 based on the monotonic mapping relationship between the change between the first and second temperatures and the fan speed. That is, the input parameter of the monotonic mapping relationship is the change between the first and second temperatures, and the output parameter is the third duty cycle parameter d3. The implementation of this monotonic mapping relationship can be, but is not limited to, a function, formula, graph, or curve. Furthermore, this monotonic mapping relationship can be expressed as follows: when the temperature change trend of the power module 11 is positively increasing, the third duty cycle parameter d3 increases; when the temperature change trend of the power module 11 is negatively decreasing, the third duty cycle parameter d3 decreases. For example, when the monotonic mapping relationship is an integral formula, the third duty cycle parameter d3 is the value obtained by integrating the change between the first and second temperatures. It should be noted that the specific implementation of this monotonic mapping relationship can be determined according to the actual application scenario and is not limited here.

[0059] In some feasible implementations, the controller 10 can adjust the target fan duty cycle d based on the first duty cycle parameter d1, the second duty cycle parameter d2, and the third duty cycle parameter d3. out Since the first duty cycle parameter d1 is the steady-state adjustment quantity reflecting the fan speed, and the second duty cycle parameter d2 and the third duty cycle parameter d3 are the dynamic adjustment quantities reflecting the fan speed, the target fan duty cycle d out It can simultaneously reflect both the steady-state and dynamic adjustment of the fan speed, thereby improving the target fan duty cycle d. out The accuracy of the target fan duty cycle d. At this point, controller 10 determines the target fan duty cycle d. outControlling the speed of each cooling fan can reduce the number of temperature cycles and the temperature cycle amplitude of the power module 11, thereby effectively suppressing the temperature cycle of the power module 11, thus improving the safety of the power module 11 and making it highly applicable.

[0060] Specifically, the controller 10 can also obtain the weighting coefficients of each duty cycle parameter among the first duty cycle parameter d1, the second duty cycle parameter d2, and the third duty cycle parameter d3, and adjust the target fan duty cycle d based on each duty cycle parameter and its weighting coefficients. out The weighting coefficient can be greater than or equal to 0 and less than or equal to 1. This weighting coefficient can be a preset parameter set by the inverter 1 at the factory, a parameter set by the user, or a parameter dynamically adjusted according to the specific operating conditions of the inverter 1. The specific parameter can be determined according to the actual application scenario and is not limited here. The target fan duty cycle d... out This value can be obtained by weighting and summing the various duty cycle parameters and their weighting coefficients. It can be understood that the controller 10 uses weighting coefficients to flexibly control the proportions of each duty cycle parameter, thereby reducing the number of temperature cycles and the amplitude of temperature cycles in the power module 11 to suppress temperature cycling, improving the safety of the power module 11 and enhancing its applicability.

[0061] In some feasible implementations, the target fan duty cycle d is adjusted. out Subsequently, controller 10 operates at the target fan duty cycle d. out When the duty cycle is less than a preset duty cycle threshold, the speed of some cooling fans (15a to 15n) is controlled to be 0, while the speed of the other cooling fans is controlled to be a first speed. The number of the other cooling fans and the first speed are determined by a second temperature and a second signal, and the first speed is less than the preset speed threshold. The number of the other cooling fans can be understood as the number of operating cooling fans, which can be represented as N, where N≥1. The first speed can be understood as the operating speed of the cooling fans. The preset duty cycle threshold is a parameter configured at the factory of inverter 1 or a parameter set by the user. The preset speed threshold refers to the maximum speed value of the cooling fans operating in the low-speed range. When the speed of some cooling fans is 0, it means that some cooling fans are not operating; when the speed of the other cooling fans is the first speed, it means that the other cooling fans are operating in the low-speed range.

[0062] It is understandable that the target fan duty cycle d outWhen the duty cycle is less than the preset duty cycle threshold, the controller 10 will flexibly control the number and speed of the cooling fans in the low-speed range. For example, by flexibly controlling different combinations of the number and speed of the cooling fans, the heat dissipation efficiency range of the cooling system in the inverter 1 can be expanded, that is, the equivalent efficiency adjustment range of the cooling system is improved, thereby effectively suppressing the temperature cycle number of the power module 11 and significantly reducing the losses of the inverter 1, making it more applicable.

[0063] For ease of description, we will use cooling fans 15a, 15b, and 15n as examples. Different combinations of the number of operating fans among cooling fans 15a, 15b, and 15n can be represented as 011, 101, 110, or 010. Here, 1 indicates that the fan speed is the first speed, meaning the fan is running at the first speed; 0 indicates that the fan speed is 0, meaning the fan is not running. For example, when the different combinations of the number of operating fans are 011, cooling fan 15a is not running, cooling fan 15b is running at the first speed, and cooling fan 15n is running at the first speed. The different combinations of operating speeds for each cooling fan can be represented as (D1-D2-D3), where D1 represents the speed of cooling fan 15a, D2 represents the speed of cooling fan 15b, and D3 represents the speed of cooling fan 15n, and any one of D1, D2, and D3 is 0 or the first speed.

[0064] In some feasible implementations, the controller 10 can target the fan duty cycle d. out When the duty cycle is greater than or equal to the preset duty cycle threshold, based on the target fan duty cycle d out The rotational speed of cooling fans 15a to 15n is defined as the second rotational speed. This second rotational speed is greater than the first rotational speed, and refers to any rotational speed value of the cooling fan operating at high speed. This second rotational speed can be determined by the target fan duty cycle d. out The second temperature and the second signal determine this. It can be understood that the target fan duty cycle d... out When the duty cycle is greater than or equal to a preset duty cycle threshold, controller 10 will control all cooling fans to run simultaneously to quickly dissipate heat from power module 11, thereby improving the heat dissipation efficiency of inverter 1 and making it highly adaptable. In summary, controller 10 can control the target fan duty cycle d... out The system compares the cooling fan 15a to the cooling fan 15n with a preset duty cycle threshold and flexibly controls the cooling fan 15a to the cooling fan 15n to operate at low or high speed based on the comparison result, thereby expanding the working range of the cooling system to improve cooling efficiency and making it more versatile.

[0065] For ease of description, the following explanation will use the first and second signals as examples of output power. In one embodiment, the controller 10 is based on the aforementioned target fan duty cycle d. out Control the speed of each cooling fan from cooling fan 15a to cooling fan 15n. The speed can be 0, a first speed, or a second speed. The effect of suppressing temperature cycling in the power module 11 under these conditions can be found in [reference needed]. Figure 3A , Figure 3A This is a schematic diagram illustrating the effect of suppressing temperature cycling in the power module provided in this application. In another embodiment, the controller 10 obtains the fan duty cycle based solely on the current temperature of the power module 11, and controls the speed of each cooling fan from cooling fan 15a to cooling fan 15n based on this fan duty cycle. The effect of suppressing temperature cycling in the power module 11 in this case can be seen in [reference needed]. Figure 3B , Figure 3B This is another schematic diagram illustrating the effect of suppressing temperature cycling of the power module provided in this application.

[0066] contrast Figure 3A and Figure 3B The diagram shows that, under the condition that the power change trend is consistent, Figure 3A The power module 11 shown has a smaller temperature fluctuation range and amplitude; therefore, the controller 10 is based on the target fan duty cycle d. out Controlling the speed of each cooling fan can quickly reflect the power change trend and temperature change trend, effectively suppressing the number of temperature cycles and the temperature cycle amplitude of the power module 11, thereby improving the reliability of the inverter 1 and reducing the failure rate of the inverter 1.

[0067] In some feasible implementations, the specific structure of the inverter 1 described above can also be found in [reference needed]. Figure 4 , Figure 4 This is another structural schematic diagram of the inverter provided in this application. For example... Figure 4 As shown, the power module 11 includes power units 110a to 110m. Figure 2The inverter 1 shown also includes a heat sink 16 and thermal paste 17a to 17m. Power units 110a to 110m can be mounted on the surface of the heat sink 16, and each power unit 110a to 110m has thermal paste between it and the heat sink 16. For example, thermal paste 17a is between power unit 110a and the heat sink 16, thermal paste 17b is between power unit 110b and the heat sink 16, and so on, with thermal paste 17m between power unit 110m and the heat sink 16. The power units 110a to 110m, cooling fans 15a to 15n, the heat sink 16, and thermal paste 17a to 17m constitute the heat dissipation system of the inverter 1. This heat dissipation system includes, but is not limited to, heat pipes and air ducts. The number and arrangement of various types of components in the heat dissipation system can be determined by the specific type of inverter 1 and are not limited here. Among them, a heat pipe is a heat transfer element, and an air duct is a channel for air circulation constructed of materials such as concrete and bricks.

[0068] In some feasible implementations, power units 110a to 110m can perform AC-DC conversion on the DC input signal to output a first signal or a second signal. During this output process, power units 110a to 110m will continuously generate heat. At this time, cooling fans 15a to 15n can operate at a certain speed to draw external air into the heat sink 16 through the air duct, thereby exchanging heat with the heat sink 16 through the airflow to dissipate the heat generated by power units 110a to 110m, thus ensuring the reliability and safety of the power module 11.

[0069] In some feasible implementations, in order to quickly dissipate heat from the power module 11, the controller 10 can control the speed of each of the cooling fans 15a to 15n in real time. For example... Figure 4 As shown above, Figure 2 The controller 10 shown may include, but is not limited to, an output signal sampling unit 101 and a fan speed control unit 102. Optionally, the output signal sampling unit 101 may also be located outside the controller 10. When the output signal of the power module 11 is output power, the output signal sampling unit 101 may include, but is not limited to, a power detection circuit or a power meter; when the output signal of the power module 11 is output current, the output signal sampling unit 101 may include, but is not limited to, a current detection circuit or a current meter.

[0070] In some feasible implementations, the temperature detection device 14 and the output signal sampling unit 101 can establish wired or wireless communication with the fan speed control unit 102 to transmit temperature data and signal data. During the control of the rotational speed of each cooling fan, the temperature detection device 14 can detect the first temperature when the power module 11 outputs the first signal and the second temperature when the power module 11 outputs the second signal, and output the first and second temperatures to the fan speed control unit 102; the output signal sampling unit 101 can detect the first and second signals output by power units 110a to 110m through the output port 13, and output the first and second signals to the fan speed control unit 102.

[0071] Furthermore, the fan speed control unit 102 can adjust the target fan duty cycle d based on the second signal, the change between the first and second signals, the second temperature, and the change between the first and second temperatures. out The system generates duty cycle commands and outputs them to cooling fans 15a to 15n, thereby controlling the speed of each cooling fan from 15a to 15n. The duty cycle command, also known as the fan speed control command, includes the target fan duty cycle d. out For the detailed calculation process, please refer to the above. Figure 2 In the corresponding embodiment, regarding the target fan duty cycle d out The description will not be repeated here. After receiving the duty cycle command, each of the cooling fans 15a to 15n can operate according to the duty cycle command to dissipate heat from the power module 11, thereby reducing the temperature fluctuation of the heat sink 16 and the power module 11, effectively suppressing the temperature cycle of the power module 11, and making it highly applicable.

[0072] In the inverter 1 provided in this application, the controller 10 can dynamically adjust the duty cycle of the target fan based on the second signal, the change between the first and second signals, the second temperature, and the change between the first and second temperatures. This allows for rapid control of the speed of each cooling fan, reducing the number and amplitude of temperature cycles in the power module 11, thereby improving the safety of the power module 11. Furthermore, it reduces the lifespan loss of the power module 11 and improves its reliability. Further, the controller 10 can adjust the duty cycle d of the target fan. out The system compares the cooling fan 15a to the cooling fan 15n with a preset duty cycle threshold and flexibly controls the cooling fan 15a to the cooling fan 15n to operate at low or high speed based on the comparison result, thereby expanding the working range of the cooling system to improve cooling efficiency and making it more versatile.

[0073] The following example illustrates a photovoltaic system that includes an inverter; please refer to [link / reference needed]. Figure 5, Figure 5 This is a structural schematic diagram of the photovoltaic system provided in this application. Figure 5 As shown, the photovoltaic system 2 includes a photovoltaic array 20 and an inverter 30 (as described in inverter 1) connected to the photovoltaic array 20 (e.g., directly or indirectly). The output of the inverter 30 can be connected (e.g., directly or indirectly) to the AC power grid. During the process of supplying power to the AC power grid, the inverter 30 can convert the DC voltage provided by the photovoltaic array 20 into AC voltage and supply power to the AC power grid based on the AC voltage. When the inverter 30 includes a cooling fan and a controller, the controller can control the speed of the cooling fan in real time to ensure the reliable operation of the inverter 30. Therefore, the power supply reliability and security of the inverter 30 are higher, thereby improving the power supply efficiency and security of the photovoltaic system 2, and providing strong adaptability.

[0074] In some feasible implementations, the specific structure of the photovoltaic system 2 described above can also be found in [reference needed]. Figure 6 , Figure 6 This is another structural schematic diagram of the photovoltaic system provided in this application. (See diagram below.) Figure 6 As shown, the photovoltaic system 2 also includes a DC combiner box 40. The photovoltaic array 20 can be connected to the input terminal of the inverter 30 through the DC combiner box 40, and the output terminal of the inverter 30 can be connected (e.g., directly or indirectly) to the AC power grid. During the process of supplying power to the AC power grid, the DC combiner box 40 can combine the DC voltages provided by each photovoltaic string in the photovoltaic array 20 and output them to the inverter 30. At this time, the inverter 30 (e.g., a centralized photovoltaic inverter) can supply power to the AC power grid based on the combined DC voltage. During this power supply process, because the inverter 30 has higher power supply reliability and security, the power supply efficiency and security of the photovoltaic system 2 can be improved, and its adaptability is stronger.

[0075] Optional, such as Figure 6 As shown, the photovoltaic system 2 also includes a box-type transformer 50. The output of the inverter 30 can be connected to the AC power grid through the box-type transformer 50. The box-type transformer 50 refers to a substation (or distribution station) that combines high-voltage switchgear, distribution transformers, and low-voltage distribution devices according to a specific wiring scheme and installs them within a box-type enclosure. During the process of supplying power to the AC power grid, the inverter 30 (such as a centralized photovoltaic inverter) can output AC voltage to the box-type transformer 50 based on the combined DC voltage. At this time, the box-type transformer 50 can supply power to the AC power grid based on the AC voltage input to the inverter 30. In this power supply process, because the inverter 30 has higher power supply reliability and security, the power supply efficiency and security of the photovoltaic system 2 can be improved, and its adaptability is stronger.

[0076] In some feasible implementations, the specific structure of the photovoltaic system 2 described above can also be found in [reference needed]. Figure 7 , Figure 7 This is another structural schematic diagram of the photovoltaic system provided in this application. (See diagram below.) Figure 7 As shown above, Figure 5 The photovoltaic system 2 shown also includes an AC combiner box 60. The photovoltaic array 20 can be connected to the input terminal of the AC combiner box 60 via an inverter 30, and the output terminal of the AC combiner box 60 can be connected (e.g., directly or indirectly) to the AC power grid. During the supply of power to the AC power grid, the inverter 30 can provide AC voltage to the AC combiner box 60 based on the DC voltage provided by the photovoltaic array 20. The AC combiner box 60 can supply power to the AC power grid using the AC voltage input to the inverter 30 (e.g., a string photovoltaic inverter). In this power supply process, because the inverter 30 has higher power supply reliability and security, the power supply efficiency and security of the photovoltaic system 2 can be improved, and its adaptability is enhanced.

[0077] Optional, such as Figure 7 As shown, the photovoltaic system 2 also includes a box-type transformer 51, and the output of the AC combiner box 60 can be connected to the AC power grid through the box-type transformer 51. During the process of supplying power to the AC power grid, the AC combiner box 60 can combine the AC voltage input to the inverter 30 (such as a string photovoltaic inverter) and output it to the box-type transformer 51. At this time, the box-type transformer 51 can supply power to the AC power grid based on the combined AC voltage. During this power supply process, because the inverter 30 has higher power supply reliability and security, the power supply efficiency and security of the photovoltaic system 2 can be improved, and its adaptability is stronger.

[0078] In some feasible implementations, the specific structure of the photovoltaic system 2 described above can also be found in [reference needed]. Figure 8 , Figure 8 This is another structural schematic diagram of the photovoltaic system provided in this application. (See diagram below.) Figure 8 As shown above, Figure 5 The photovoltaic system 2 shown also includes a DC / DC converter 70 and a DC bus 80. The photovoltaic array 20 can be connected to the input terminal of the inverter 30 via the DC / DC converter 70 and the DC bus 80. The output terminal of the inverter 30 can be connected to the AC power grid. The DC bus 80 may include a positive DC bus and a negative DC bus (e.g., ...). Figure 1(The positive and negative DC buses are shown). During the process of supplying power to the AC grid, the DC / DC converter 70 can convert the DC voltage provided by the photovoltaic array 20 into a target DC voltage and output the target DC voltage to the inverter 30 through the DC bus 80. At this time, the inverter 30 can convert the target DC voltage into AC voltage and supply power to the AC grid based on the AC voltage. In this power supply process, because the inverter 30 has higher power supply reliability and security, the power supply efficiency and security of the photovoltaic system 2 can be improved, and its adaptability is stronger.

[0079] In the photovoltaic system 2 provided in this application, since the inverter 30 has higher power supply reliability and power supply security, the power supply efficiency and power supply security of the photovoltaic system 2 can be improved, and the system power supply flexibility and adaptability are stronger.

[0080] The following example illustrates how to adjust the speed of the inverter's cooling fan. Please refer to [link / reference]. Figure 9 , Figure 9 This is a flowchart illustrating a method for adjusting the speed of an inverter cooling fan as provided in this application. This method is applicable to inverters (such as those described above). Figures 2 to 4 The inverter 1) shown includes a controller, and the inverter also includes a power module and at least one cooling fan. Figure 9 As shown, the method includes the following steps S101 to S102:

[0081] Step S101: Detect the first temperature when the power module outputs the first signal and the second temperature when the power module outputs the second signal.

[0082] In some feasible implementations, each of the first and second signals mentioned above may include, but is not limited to, output power or output current, and the detection time of the first temperature is before the detection time of the second temperature. Specifically, the controller can detect the first and second temperatures of the power module through a temperature detection device, thereby ensuring the accuracy and real-time performance of temperature sampling. The temperature detection device may include, but is not limited to, thermocouples, positive temperature coefficient thermistors, negative temperature coefficient thermistors, silicon resistance temperature sensors, IC temperature sensors, or other temperature-sensitive devices. The first or second temperature can be understood as the temperature of the inverter, and the first or second temperature includes, but is not limited to, the temperature of the power module, the internal air temperature of the inverter, the temperature of the power board, or the temperature of the heat sink. For ease of description, the following will use the example of the first or second temperature including the temperature of the power module, and will not be elaborated further. In this case, the second temperature can be understood as the current temperature of the power module, and the second signal can be understood as the current output signal of the power module.

[0083] In some feasible implementations, the controller can detect the first and second temperatures of the power module using a temperature detection device, and also detect the first and second signals of the power module, thereby completing the real-time detection process of the inverter's operating status. In one embodiment, when each of the first and second signals represents output power, the controller can detect the first and second output power of the power module using a power detection circuit or a power meter, thereby ensuring the accuracy and real-time performance of power sampling. In another embodiment, when each signal represents output current, the controller can detect the first and second output current of the power module using a current detection circuit or a current meter, thereby ensuring the accuracy and real-time performance of current sampling.

[0084] Step S102: Adjust the duty cycle of the target fan according to the second signal, the change between the first signal and the second signal, the second temperature, and the change between the first temperature and the second temperature, so as to control the speed of each cooling fan in at least one cooling fan.

[0085] In some feasible implementations, the change between the first temperature and the second temperature includes at least one of the following: the difference between the first temperature and the second temperature, the rate of change, the direction of change, and the time difference. The rate of change is the ratio between the difference between the first temperature and the second temperature and the detection time difference. The direction of change is the temperature change trend of the power module, which can be either positively increasing or negatively decreasing. The detection time difference is the difference between the detection time of the first temperature and the detection time of the second temperature, and this detection time difference is greater than 0. When the first temperature is greater than the second temperature, the difference between the first temperature and the second temperature and the rate of change are less than 0, and the direction of change between the first temperature and the second temperature is negatively decreasing, meaning the temperature change trend of the power module is negatively decreasing. When the first temperature is less than the second temperature, the difference between the first temperature and the second temperature and the rate of change are greater than 0, and the direction of change between the first temperature and the second temperature is positively increasing, meaning the temperature change trend of the power module is positively increasing.

[0086] In some feasible implementations, the change between the first signal and the second signal includes, but is not limited to, at least one of the following: the difference between the first signal and the second signal, the rate of change, the direction of change, and the time difference. The rate of change is the ratio between the difference between the first signal and the second signal and the time difference. The direction of change is the output change trend of the power module, which includes a positive increase or a negative decrease. When each of the first and second signals represents output power, the output change trend of the power module is a power change trend; when each of the first and second signals represents output current, the output change trend of the power module is a current change trend. The time difference is the difference between the detection time of the first signal and the detection time of the second signal, and the time difference is greater than 0. When the first signal is greater than the second signal, the difference and rate of change between the first and second signals are less than 0, and the direction of change between the first and second signals is a negative decrease, meaning the output change trend of the power module is a negative decrease. When the first signal is less than the second signal, the difference and rate of change between the first and second signals are greater than 0, and the direction of change between the first signal and the second signal is a positive increase, meaning the output change trend of the power module is a positive increase.

[0087] In some feasible implementations, the operations performed by the controller in controlling the speed of each cooling fan can be found in [reference needed]. Figure 10 , Figure 10 This is another flowchart illustrating the speed control method for the inverter cooling fan provided in this application. For example... Figure 10 As shown, the method includes the following steps S1021 to S1026:

[0088] Step S1021: Obtain the first duty cycle parameter d1 based on the second signal and the second temperature.

[0089] In some feasible implementations, the controller can output a first duty cycle parameter d1 based on the monotonic mapping relationship between the second signal, the second temperature, and the fan speed. That is, the input parameters of the monotonic mapping relationship are the second temperature and the second signal, and the output parameter is the first duty cycle parameter d1. The implementation of this monotonic mapping relationship includes, but is not limited to, functions, formulas, graphs, or curves. Furthermore, this monotonic mapping relationship can be expressed as follows: when the temperature of the power module increases or the output signal of the power module increases, the first duty cycle parameter d1 increases; when the temperature of the power module decreases or the output signal of the power module decreases, the first duty cycle parameter d1 decreases. The first duty cycle parameter d1 can be understood as a fan speed control quantity, and it reflects the steady-state adjustment of the fan speed.

[0090] Optionally, the controller can also obtain a first duty cycle parameter d based on the second signal.11 And based on the second temperature, another first duty cycle parameter d is obtained. 12 Among them, the first duty cycle parameter d 11 and the first duty cycle parameter d 12 This can be understood as the fan speed control variable, and the first duty cycle parameter d 11 To reflect the steady-state adjustment of the fan speed associated with the second signal, the first duty cycle parameter d 12 This reflects the steady-state adjustment of the fan speed in relation to the second temperature. For ease of description, the first duty cycle parameter d1 will be used as an example below, and will not be elaborated further.

[0091] Step S1022: Obtain the second duty cycle parameter d2 based on the change between the first signal and the second signal.

[0092] Specifically, the controller can also output a second duty cycle parameter d2 based on the monotonic mapping relationship between the change between the first and second signals and the fan speed. That is, the input parameter of the monotonic mapping relationship is the change between the first and second signals, and the output parameter is the second duty cycle parameter d2. This monotonic mapping relationship can be implemented, including but not limited to, functions, formulas, graphs, or curves. Furthermore, this monotonic mapping relationship can be expressed as follows: when the output of the power module increases positively, the second duty cycle parameter d2 increases; when the output of the power module decreases negatively, the second duty cycle parameter d2 decreases. For example, when the monotonic mapping relationship is a differential formula, the second duty cycle parameter d2 is the value obtained by differentiating the change between the first and second signals. It should be noted that the specific implementation of this monotonic mapping relationship can be determined according to the actual application scenario and is not limited here.

[0093] The second duty cycle parameter d2 can be understood as the fan speed control quantity. The second duty cycle parameter d2 reflects the dynamic adjustment quantity of the fan speed, which can reduce the impact of sudden changes in light and load on the temperature cycle number and temperature cycle amplitude of the power module, thereby reducing the temperature cycle number and temperature cycle amplitude of the power module and effectively suppressing the temperature cycle of the power module.

[0094] Step S1023: Obtain the third duty cycle parameter d3 based on the change between the first temperature and the second temperature.

[0095] Specifically, the controller can also output a third duty cycle parameter d3 based on the monotonic mapping relationship between the change between the first and second temperatures and the fan speed. That is, the input parameter of the monotonic mapping relationship is the change between the first and second temperatures, and the output parameter is the third duty cycle parameter d3. This monotonic mapping relationship can be implemented, but is not limited to, functions, formulas, graphs, or curves. Furthermore, this monotonic mapping relationship can be expressed as follows: when the temperature change trend of the power module is positively increasing, the third duty cycle parameter d3 increases; when the temperature change trend of the power module is negatively decreasing, the third duty cycle parameter d3 decreases. For example, when the monotonic mapping relationship is an integral formula, the third duty cycle parameter d3 is the value obtained by integrating the change between the first and second temperatures. It should be noted that the specific implementation method of this monotonic mapping relationship can be determined according to the actual application scenario and is not limited here.

[0096] The third duty cycle parameter d3 can be understood as the fan speed control quantity. The third duty cycle parameter d3 reflects the dynamic adjustment of the fan speed, which can reduce the impact of the start and stop of the cooling fan and the ambient temperature on the temperature cycle number and temperature cycle amplitude of the power module. This can reduce the temperature cycle amplitude of the power module in power fluctuation scenarios, thus avoiding large fluctuations in the temperature cycle amplitude of the power module in power fluctuation scenarios.

[0097] Step S1024: Adjust the target fan duty cycle d based on the first duty cycle parameter d1, the second duty cycle parameter d2, and the third duty cycle parameter d3. out .

[0098] Wherein, since the first duty cycle parameter d1 is the steady-state adjustment quantity reflecting the fan speed, and the second duty cycle parameter d2 and the third duty cycle parameter d3 are the dynamic adjustment quantities reflecting the fan speed, therefore, the target fan duty cycle d out It can simultaneously reflect both the steady-state and dynamic adjustment of the fan speed, thereby improving the target fan duty cycle d. out The accuracy.

[0099] Specifically, the controller can also obtain the weighting coefficients of each duty cycle parameter among the first duty cycle parameter d1, the second duty cycle parameter d2, and the third duty cycle parameter d3, and adjust the target fan duty cycle d based on each duty cycle parameter and its weighting coefficients. out The weighting coefficient can be greater than or equal to 0 and less than or equal to 1. This weighting coefficient can be a preset parameter set by the inverter at the factory, a parameter set by the user, or a parameter dynamically adjusted according to the specific operating conditions of the inverter. The specific value can be determined based on the actual application scenario and is not limited here. The target fan duty cycle d... outThis value can be obtained by weighting and summing the various duty cycle parameters and their weighting coefficients. It can be understood that the controller uses weighting coefficients to flexibly control the proportions of each duty cycle parameter, thereby reducing the number and amplitude of temperature cycles in the power module to suppress temperature cycling, improving the safety of the power module and enhancing its applicability.

[0100] Step S1025, at the target fan duty cycle d out When the duty cycle is less than a preset threshold, control the speed of a portion of the cooling fans to 0 and the speed of the other portion of the cooling fans to the first speed.

[0101] In this configuration, the number and initial speed of another portion of the cooling fans are determined by the second temperature and the second signal, with the initial speed being less than a preset speed threshold. The number of these other cooling fans can be understood as the number of operating fans, which can be represented as N, where N≥1. The initial speed can be understood as the operating speed of the cooling fans. The preset duty cycle threshold is a parameter configured at the inverter's factory or set by the user, and the preset speed threshold refers to the maximum speed value of the cooling fans operating in the low-speed range. When the speed of some cooling fans is 0, it indicates that some cooling fans are not operating; when the speed of another portion of the cooling fans is the first speed, it indicates that the other portion of the cooling fans are operating in the low-speed range.

[0102] At the target fan duty cycle d out When the duty cycle is less than the preset threshold, the controller will flexibly control the number and speed of the cooling fans in the low-speed range. For example, by flexibly controlling different combinations of the number of fans and different combinations of the speed, the heat dissipation efficiency range of the cooling system in the inverter can be expanded, that is, the equivalent efficiency adjustment range of the cooling system is improved, thereby effectively suppressing the temperature cycle number of the power module and significantly reducing the inverter's losses, making it more versatile.

[0103] Step S1026, at the target fan duty cycle d out If the duty cycle is greater than or equal to the preset duty cycle threshold, the speed of at least one cooling fan is controlled to the second speed based on the target fan duty cycle.

[0104] The second speed is greater than the first speed, and the second speed refers to any speed value of the cooling fan operating at high speed. This second speed can be determined by the target fan duty cycle d. out The second temperature and the second signal determine the target fan duty cycle d. out When the duty cycle is greater than or equal to a preset threshold, the controller will operate all cooling fans simultaneously to rapidly dissipate heat from the power module, thereby improving the inverter's heat dissipation efficiency and offering broad applicability. In summary, the controller can control the target fan duty cycle d...out It compares the current with a preset duty cycle threshold and flexibly controls at least one cooling fan to operate at low or high speed based on the comparison result, thereby expanding the working range of the cooling system to improve cooling efficiency and making it more versatile.

[0105] In specific implementation, further operations performed by the controller in the inverter cooling fan speed control method provided in this application can be found in the above-mentioned... Figures 2 to 4 The implementation method of the inverter 1 shown and the working principle of the controller 10 will not be described in detail here.

[0106] In the method provided in this application, the controller can dynamically adjust the duty cycle of the target fan based on the second signal, the change between the first and second signals, the second temperature, and the change between the first and second temperatures. This allows for rapid control of the speed of each cooling fan, reducing the number and amplitude of temperature cycles in the power module, thereby improving the safety of the power module. Furthermore, it reduces the lifespan loss of the power module and improves its reliability. Further, the controller can compare the duty cycle of the target fan with a preset duty cycle threshold and flexibly control at least one cooling fan to operate at low or high speed based on the comparison result. This broadens the operating range of the cooling system, improving heat dissipation efficiency and enhancing its applicability.

[0107] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An inverter, characterized in that, The inverter includes a controller, a power module, a temperature detection device, at least one cooling fan, a power board, and a heat sink; The power board is used to carry the power module; The heat sink is used to dissipate heat from the power module; The power module is used to convert the DC input signal into AC or DC to output power or output current. The temperature detection device is used to detect the first temperature of the power module when it outputs power or current at a first moment and the second temperature of the power module when it outputs power or current at a second moment. The first moment of the first temperature detection is before the second moment of the second temperature detection. The temperature detection device includes a negative temperature coefficient thermistor or a silicon resistance temperature sensor. The controller is configured to adjust the duty cycle of the target fan based on the output current or output power at the second time, the change between the output current or output power at the first time and the output current or output power at the second time, the second temperature, and the change between the first temperature and the second temperature, so as to control the speed of each cooling fan in the at least one cooling fan to dissipate heat from the power module. The first temperature or the second temperature includes: the temperature of the power module, the internal air temperature of the inverter, the temperature of the power board, or the temperature of the heat sink.

2. The inverter according to claim 1, characterized in that, The change between the output current or output power at the first moment and the output current or output power at the second moment includes at least one of the following: the difference between the output current or output power at the first moment and the output current or output power at the second moment, the rate of change, the direction of change, and the time difference; the change between the first temperature and the second temperature includes at least one of the following: the difference between the first temperature and the second temperature, the rate of change, the direction of change, and the detection time difference.

3. The inverter according to any one of claims 1 or 2, characterized in that, The controller is used for: The first duty cycle parameter is obtained based on the output current or output power at the second moment and the second temperature. A second duty cycle parameter is obtained based on the change between the output current or output power at the first time and the output current or output power at the second time, and a third duty cycle parameter is obtained based on the change between the first temperature and the second temperature. The duty cycle of the target fan is adjusted according to the first duty cycle parameter, the second duty cycle parameter, and the third duty cycle parameter.

4. The inverter according to claim 3, characterized in that, The controller is used for: Obtain the weighting coefficients of each duty cycle parameter among the first duty cycle parameter, the second duty cycle parameter, and the third duty cycle parameter, and adjust the target fan duty cycle based on each duty cycle parameter and its weighting coefficients, wherein the weighting coefficients are greater than or equal to 0 and less than or equal to 1.

5. The inverter according to any one of claims 1-4, characterized in that, The controller is used for: When the duty cycle of the target fan is less than a preset duty cycle threshold, the speed of a portion of the at least one cooling fan is controlled to be 0 and the speed of another portion of the cooling fans is controlled to be a first speed. The number of the other portion of cooling fans and the first speed are determined by the second temperature and the output current or output power at the second time. The first speed is less than a preset speed threshold. When the target fan duty cycle is greater than or equal to the preset duty cycle threshold, the rotation speed of at least one cooling fan is controlled to a second rotation speed based on the target fan duty cycle, wherein the second rotation speed is greater than the first rotation speed.

6. A method for adjusting the speed of an inverter cooling fan, characterized in that, The method is applicable to a controller in an inverter, the inverter further comprising a power module and at least one cooling fan; the method includes: The power module is used to detect a first temperature when it outputs current or power at a first moment and a second temperature when it outputs current or power at a second moment. The first temperature or the second temperature includes: the temperature of the power module, the internal air temperature of the inverter, the temperature of the power board, or the temperature of the heat sink. The detection time of the first temperature is before the detection time of the second temperature. The duty cycle of the target fan is adjusted based on the output current or output power at the second time, the change between the output current or output power at the first time and the output current or output power at the second time, the second temperature, and the change between the first temperature and the second temperature, so as to control the speed of each cooling fan in the at least one cooling fan.

7. The method according to claim 6, characterized in that, The inverter also includes a power board and a heat sink, wherein the power board is used to support the power module and the heat sink is used to dissipate heat from the power module.

8. The method according to claim 6 or 7, characterized in that, The change between the output current or output power at the first moment and the output current or output power at the second moment includes at least one of the following: the difference between the output current or output power at the first moment and the output current or output power at the second moment, the rate of change, the direction of change, and the time difference; the change between the first temperature and the second temperature includes at least one of the following: the difference between the first temperature and the second temperature, the rate of change, the direction of change, and the detection time difference.

9. The method according to claim 7 or 8, characterized in that, The step of adjusting the target fan duty cycle based on the output current or output power at the second time moment, the change between the output current or output power at the first time moment and the output current or output power at the second time moment, the second temperature, and the change between the first temperature and the second temperature includes: The first duty cycle parameter is obtained based on the output current or output power at the second moment and the second temperature. A second duty cycle parameter is obtained based on the change between the output current or output power at the first time and the output current or output power at the second time, and a third duty cycle parameter is obtained based on the change between the first temperature and the second temperature. Adjust the target fan duty cycle according to the first duty cycle parameter, the second duty cycle parameter, and the third duty cycle parameter.

10. The method according to claim 9, characterized in that, The step of adjusting the target fan duty cycle according to the first duty cycle parameter, the second duty cycle parameter, and the third duty cycle parameter includes: Obtain the weighting coefficients of each duty cycle parameter among the first duty cycle parameter, the second duty cycle parameter, and the third duty cycle parameter, and adjust the target fan duty cycle based on each duty cycle parameter and its weighting coefficients, wherein the weighting coefficients are greater than or equal to 0 and less than or equal to 1.

11. The method according to any one of claims 7-10, characterized in that, After adjusting the target fan duty cycle based on the output current or output power at the second time, the change between the output current or output power at the first time and the output current or output power at the second time, the second temperature, and the change between the first temperature and the second temperature, the method further includes: When the duty cycle of the target fan is less than a preset duty cycle threshold, the speed of a portion of the at least one cooling fan is controlled to be 0 and the speed of another portion of the cooling fans is controlled to be a first speed. The number of the other portion of cooling fans and the first speed are determined by the second temperature and the output current or output power at the second time. The first speed is less than a preset speed threshold. When the target fan duty cycle is greater than or equal to the preset duty cycle threshold, the rotation speed of at least one cooling fan is controlled to a second rotation speed based on the target fan duty cycle, wherein the second rotation speed is greater than the first rotation speed.

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