Inverter, speed regulation method of cooling fan of inverter, and photovoltaic system

Abstract

The invention provides an inverter, a speed regulation method of a cooling fan of the inverter and a photovoltaic system. The inverter comprises a controller, a power module, an input port, an output port, a temperature detection device and at least one cooling fan. Wherein the temperature detection device is used for detecting a first temperature when the power module outputs the first signal and a second temperature when the power module outputs the second signal, and the detection time of the first temperature is before the detection time of the second temperature. Furthermore, the controller is used for adjusting the duty ratio of the target fan according to the second signal, the variable quantity between the first signal and the second signal, the second temperature and the variable quantity between the first temperature and the second temperature so as to quickly control the rotating speed of each cooling fan in the at least one cooling fan, therefore, the temperature cycle index and the temperature cycle amplitude of the power module can be reduced, the temperature cycle of the power module is effectively inhibited, the safety and the reliability of the power module are improved, and the applicability is high.

Description

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

[0002] The present application relates to the field of electronic power technology, and in particular to an inverter and a speed regulation method of a cooling fan thereof, and a photovoltaic system. Background Art

[0003] In order to ensure the safe and reliable operation of the inverter, the fan in the inverter will cool the heat generated by the power module to make the temperature of the power module lower than the safe allowable junction temperature, thereby ensuring the normal operation of the power module. In the process of cooling the heat generated by the power module, the fan speed will be adjusted to suppress the temperature cycle of the power module, thereby improving the safety and reliability of the power module.

[0004] In the prior art, the fan start and stop temperature points are adjusted according to the operating state of the inverter to dynamically fit the fan speed curve, and the fan speed is adjusted according to the speed curve to quickly cool the power module, thereby ensuring the safe operation of the power module. However, in the case of a sudden change in the power of the inverter (or frequent changes in power), the fan will be frequently started and stopped to increase the number and amplitude of the temperature cycle of the power module, thereby failing to effectively suppress the temperature cycle of the power module, resulting in poor safety and applicability of the power module. Summary of the invention

[0005] The present application provides an inverter and a speed regulation method for a cooling fan thereof, as well as a photovoltaic system, which can reduce the number of temperature cycles and the temperature cycle amplitude of a 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] In the first aspect, the present application provides an inverter, which includes a controller, a power module, an input port and an output port, a temperature detection device and at least one cooling fan, wherein the power module and the at least one cooling fan can constitute a cooling system in the inverter, wherein the at least one cooling fan refers to one or more cooling fans. The above-mentioned input port is used to receive a DC input signal, and the output port is used to output a first signal and a second signal. The above-mentioned power module is used to perform AC-DC conversion on the DC input signal to output a first signal or a second signal, wherein each of the first signal and the second signal may include but is not limited to output power or output current. At this time, the temperature detection device is used to detect the first temperature when the power module outputs the first signal and the second temperature when the power module outputs the second signal, thereby ensuring the real-time and accuracy of temperature sampling. Among them, the detection time of the first temperature is before the detection time of the second temperature. Further, the controller is used to: adjust the target fan duty cycle according to the second signal, the change amount between the first signal and the second signal, the second temperature, and the change amount between the first temperature and the second temperature, so as to control the speed of each cooling fan in at least one cooling fan. At this time, the above-mentioned cooling fans are used to run at the speed of each cooling fan to dissipate heat for the power module.

[0007] In the present application, since the first signal, the second signal, the first temperature and the second temperature are all real-time detection data, that is, the change between the first signal and the second signal and the change between the first temperature and the second temperature are real-time changes, the controller can dynamically adjust the target fan duty cycle according to the real-time detection data and the real-time change to quickly control the speed of each cooling fan, 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, and thus improve the safety of the power module; in addition, the life loss of the power module is reduced, and the reliability of the power module is improved, and the applicability is strong.

[0008] In combination with the first aspect, in a first possible implementation manner, 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 temperature or the second temperature includes: a temperature of the power module, an internal air temperature of the inverter, a temperature of the power board, or a temperature of the heat sink.

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

[0010] In combination with any one of the first aspect to the second possible implementation of the first aspect, in a third possible implementation, in the process of adjusting 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 may also obtain a second duty cycle parameter based on the change between the first signal and the second signal, and obtain a third duty cycle parameter based on the change between the first temperature and the second temperature. Wherein, the second duty cycle parameter is a dynamic adjustment amount reflecting the fan speed, which can reduce the influence of sudden changes in illumination and load on the number of temperature cycles and the temperature cycle amplitude of the power module, thereby reducing the number of temperature cycles and the temperature cycle amplitude of the power module. The third duty cycle parameter is a dynamic adjustment amount reflecting the fan speed, which can reduce the influence of the start and stop of the cooling fan and the ambient temperature on the number of temperature cycles and the temperature cycle amplitude of the power module, thereby reducing the temperature cycle amplitude of the power module in the power fluctuation scenario, that is, avoiding the large fluctuation of the temperature cycle amplitude of the power module in the power fluctuation scenario.

[0011] Furthermore, the controller can also adjust the target fan duty cycle according to the first duty cycle parameter, the second duty cycle parameter and the third duty cycle parameter. Since the first duty cycle parameter is a steady-state adjustment amount reflecting the fan speed, and the second duty cycle parameter and the third duty cycle parameter are dynamic adjustment amounts reflecting the fan speed, the target fan duty cycle can simultaneously reflect the steady-state adjustment amount and the dynamic adjustment amount of the fan speed, thereby improving the accuracy of the target fan duty cycle, reducing the number of temperature cycles and the temperature cycle amplitude of the power module, thereby effectively suppressing the temperature cycle of the power module, and further improving the safety of the power module.

[0012] In combination with the third possible implementation of the first aspect, in a fourth possible implementation, the controller is used to obtain the weighted coefficients of each duty cycle parameter in 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 weighted coefficient. Wherein, the weighted coefficient is greater than or equal to 0 and less than or equal to 1, and the weighted 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 working conditions of the inverter. It can be understood that the controller achieves flexible control of the proportion of each duty cycle parameter through the weighted coefficient, 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 combination with any one of the first aspect to the fourth possible implementation of the first aspect, in a fifth possible implementation, after adjusting the target fan duty cycle, the controller is used to control the speed of a part of the cooling fans in at least one cooling fan to be 0 and the speed of another part of the cooling fans to be the first speed when the target fan duty cycle is less than the preset duty cycle threshold. The number of the other cooling fans and the first speed are determined by the second temperature and the second signal, and the first speed is less than the preset speed threshold; and the number of the other cooling fans can be understood as the number of cooling fans in operation, 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 fan running in the low speed section. When the speed of a part of the cooling fans is 0, it can be obtained that a part of the cooling fans are not running; when the speed of another part of the cooling fans is the first speed, it can be obtained that another part of the cooling fans are running in the low speed section. It can be understood 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 fan in operation in the low-speed section, which can expand the cooling efficiency range of the cooling system in the inverter, thereby effectively suppressing the number of temperature cycles of the power module, while greatly reducing the loss of the inverter and making it more applicable.

[0014] The above-mentioned controller 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 the preset duty cycle threshold. The second speed is greater than the first speed, and the second speed refers to any speed value of the cooling fan running in the high-speed section. 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 run simultaneously to quickly dissipate heat from the power module, thereby improving the heat dissipation efficiency of the inverter, and the applicability is strong. 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 run in the low-speed section or the high-speed section according to the comparison result, thereby broadening the working range of the cooling system to improve the heat dissipation efficiency, and the applicability is stronger.

[0015] In the second aspect, the present application provides a speed regulation method for an inverter cooling fan, which is applicable to a controller in an inverter, and the inverter also includes a power module and at least one cooling fan. In the method, the controller can detect the first temperature when the power module outputs the first signal and the second temperature when the power module outputs the second signal, thereby ensuring the real-time and accuracy of temperature sampling. Among them, each of the first signal and the second signal 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. Furthermore, the controller can adjust the target fan duty cycle 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 to control the speed of each cooling fan in at least one cooling fan.

[0016] In the present application, since the first signal, the second signal, the first temperature and the second temperature are all real-time detection data, that is, the change between the first signal and the second signal and the change between the first temperature and the second temperature are real-time changes, the controller can dynamically adjust the target fan duty cycle according to the real-time detection data and the real-time change to quickly control the speed of each cooling fan, 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, and thus improve the safety of the power module; in addition, the life loss of the power module is reduced, and the reliability of the power module is improved, and the applicability is strong.

[0017] In combination with the second aspect, in a first possible implementation manner, 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 temperature or the second temperature includes: a temperature of the power module, an internal air temperature of the inverter, a temperature of the power board, or a temperature of the heat sink.

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

[0019] In combination with any one of the second possible implementations of the second aspect to the second aspect, in a third possible implementation, in the process of adjusting 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 signal and the second signal, and obtain a third duty cycle parameter based on the change between the first temperature and the second temperature. Among them, the second duty cycle parameter is a dynamic adjustment amount reflecting the fan speed, which can reduce the influence of sudden changes in light and load on the number of temperature cycles and the temperature cycle amplitude of the power module, thereby reducing the number of temperature cycles and the temperature cycle amplitude of the power module; the third duty cycle parameter is a dynamic adjustment amount reflecting the fan speed, which can reduce the influence of the start and stop of the cooling fan and the ambient temperature on the number of temperature cycles and the temperature cycle amplitude of the power module, thereby reducing the temperature cycle amplitude of the power module in the power fluctuation scenario, that is, avoiding the large fluctuation of the temperature cycle amplitude of the power module in the power fluctuation scenario.

[0020] Furthermore, the controller can also adjust the target fan duty cycle according to the first duty cycle parameter, the second duty cycle parameter and the third duty cycle parameter. Since the first duty cycle parameter is a steady-state adjustment amount reflecting the fan speed, and the second duty cycle parameter and the third duty cycle parameter are dynamic adjustment amounts reflecting the fan speed, the target fan duty cycle can simultaneously reflect the steady-state adjustment amount and the dynamic adjustment amount of the fan speed, thereby improving the accuracy of the target fan duty cycle, reducing the number of temperature cycles and the temperature cycle amplitude of the power module, thereby effectively suppressing the temperature cycle of the power module, and further improving the safety of the power module.

[0021] In combination with the third possible implementation of the second aspect, in a fourth possible implementation, the controller may obtain the weighted coefficients of each duty cycle parameter in 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 weighted coefficient. Wherein, the weighted coefficient of any duty cycle parameter is greater than or equal to 0 and less than or equal to 1, and the weighted coefficient may 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 working conditions of the inverter. It can be understood that the controller achieves flexible control of the proportion of each duty cycle parameter through the weighted coefficient, 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 combination with any one of the second aspect to the fourth possible implementation of the second aspect, in a fifth possible implementation, after adjusting the target fan duty cycle, the controller controls the rotation speed of a part of the cooling fans in at least one cooling fan to be 0 and the rotation speed of another part of the cooling fans to be the first rotation speed when the target fan duty cycle is less than the preset duty cycle threshold. The number of the other cooling fans and the first rotation speed are determined by the second temperature and the second signal, and the first rotation speed is less than the preset rotation speed threshold; and the number of the other cooling fans can be understood as the number of cooling fans in operation, and the first rotation speed can be understood as the operating rotation speed of the cooling fans. The preset rotation speed threshold here refers to the maximum rotation speed value of the cooling fan in the low speed section. When the rotation speed of a part of the cooling fans is 0, it can be obtained that a part of the cooling fans are not running; when the rotation speed of another part of the cooling fans is the first rotation speed, it can be obtained that another part of the cooling fans are running in the low speed section. It can be understood that when the target fan duty cycle is less than the preset duty cycle threshold, the controller will flexibly control the operating quantity and operating speed of the cooling fan in the low-speed section. For example, flexible control of different operating quantity combinations and different operating speed combinations can expand the cooling efficiency range of the cooling system in the inverter, that is, improve the equivalent efficiency adjustment range of the cooling system, thereby effectively suppressing the number of temperature cycles of the power module, while greatly reducing the loss of the inverter, and making it more applicable.

[0023] The above-mentioned controller 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 the preset duty cycle threshold. The second speed is greater than the first speed, and the second speed refers to any speed value of the cooling fan running in the high-speed section. 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 run simultaneously to quickly dissipate heat from the power module, thereby improving the cooling efficiency of the inverter and having strong 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 run in the low-speed section or the high-speed section according to the comparison result, thereby broadening the working range of the cooling system to improve the cooling efficiency and having stronger applicability.

[0024] In a third aspect, the present application provides a photovoltaic system, which includes a photovoltaic array, and an inverter provided in any one of the possible implementations of the first aspect to the fifth aspect connected to the photovoltaic array, and the output end of the inverter can be connected to an AC power grid, wherein the connection includes a direct connection or an indirect connection. In the process of supplying power to the AC power grid, the inverter can convert the DC voltage provided by the photovoltaic array into an AC voltage, and supply power to the AC power grid based on the AC voltage. In the case where the inverter includes a heat dissipation system and a controller, the controller can detect the health status of the heat dissipation system in real time to ensure the reliable operation of the inverter. Therefore, the power supply reliability and power supply safety of the above-mentioned inverter are higher, thereby improving the power supply efficiency and power supply safety of the photovoltaic system, and having strong adaptability.

[0025] In combination with the third aspect, in a first possible implementation, the photovoltaic system further includes a DC combiner box, through which the photovoltaic array can be connected to the input end of the inverter, and the output end of the inverter can be connected (such as directly or indirectly) to the AC power grid. In the process of supplying power to the AC power grid, the DC combiner box can combine the DC voltage provided by each photovoltaic string in the photovoltaic array and output it 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. In this power supply process, since the inverter has higher power supply reliability and power supply safety, the power supply efficiency and power supply safety of the photovoltaic system can be improved, and the adaptability is stronger.

[0026] In combination with the first possible implementation of the third aspect, in a second possible implementation, the photovoltaic system further includes a box-type transformer, and the output end of the inverter can be connected to the AC power grid through the box-type transformer. In the process of supplying power to the AC power grid, the DC junction box can converge the DC voltage provided by each photovoltaic string in the photovoltaic array and output it 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 converged DC voltage. In this power supply process, since the inverter has higher power supply reliability and power supply safety, the power supply efficiency and power supply safety of the photovoltaic system can be improved, and the adaptability is stronger.

[0027] In combination 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 end of the AC combiner box through an inverter, and the output end of the AC combiner box can be connected (such as directly or indirectly) to the AC grid. In the process of supplying power to the AC grid, the inverter can provide an AC voltage to the AC combiner box based on the DC voltage provided by the photovoltaic array, and the AC combiner box can supply power to the AC grid with the AC voltage input by the inverter (such as a string photovoltaic inverter). In this power supply process, since the inverter has higher power supply reliability and power supply safety, the power supply efficiency and power supply safety of the photovoltaic system can be improved, and the adaptability is stronger.

[0028] In combination with the third possible implementation of the third aspect, in a fourth possible implementation, the photovoltaic system further includes a box-type transformer, and the output end of the AC combiner box can be connected to the AC power grid through the box-type transformer. In the process of supplying power to the AC power grid, the AC combiner box can combine the AC voltage input by 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. In this power supply process, since the power supply reliability and power supply safety of the inverter are higher, the power supply efficiency and power supply safety of the photovoltaic system can be improved, and the adaptability is stronger.

[0029] In combination with the third aspect, in a 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 end of the inverter through the DC / DC converter and the DC bus, and the output end of the inverter can be connected to the AC power grid. In the process of supplying 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 through the DC bus. At this time, the inverter can convert the target DC voltage into an AC voltage, and supply power to the AC power grid based on the AC voltage. In this power supply process, since the power supply reliability and power supply safety of the inverter are higher, the power supply efficiency and power supply safety of the photovoltaic system can be improved, and the adaptability is stronger.

[0030] In the present application, the controller can dynamically adjust the target fan duty cycle 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 quickly control the rotation speed of each cooling fan, which can reduce the number of temperature cycles and the temperature cycle amplitude of the power module, thereby improving the safety of the power module; in addition, the life loss of the power module is reduced and the reliability of the power module is improved. Furthermore, 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 in the low speed section or the high speed section according to the comparison result, so as to broaden the working range of the cooling system to improve the cooling efficiency, and have stronger applicability. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0032] Figure 2 It is a structural schematic diagram of the inverter provided by the present application;

[0033] Figure 3A This is a schematic diagram of an effect of suppressing the temperature cycle of a power module provided by the present application;

[0034] Figure 3B is another schematic diagram of the effect of suppressing the temperature cycle of the power module provided by the present application;

[0035] Figure 4 is another structural schematic diagram of the inverter provided by the present application;

[0036] Figure 5 is a structural schematic diagram of a photovoltaic system provided by the present application;

[0037] Figure 6 is another structural schematic diagram of the photovoltaic system provided by the present application;

[0038] Figure 7 is another structural schematic diagram of the photovoltaic system provided by the present application;

[0039] Figure 8 is another structural schematic diagram of the photovoltaic system provided by the present application;

[0040] Fig. 9 It is a flow chart of a speed regulation method of an inverter cooling fan provided by the present application;

[0041] Fig.10 It is another flow chart of the speed regulation method of the inverter cooling fan provided in the present application. DETAILED DESCRIPTION

[0042] The inverter (an AC-DC converter) provided in the present application is suitable for the fields of new energy smart microgrids, power transmission and distribution or new energy (such as photovoltaic grid-connected fields or wind grid-connected fields), photovoltaic power generation (such as photovoltaic inverters), or wind power generation, or high-power converters (such as converting DC voltage into high-power high-voltage AC power), or electric equipment (such as a variety of electric equipment) and other application fields. The specific application can be determined according to the actual application scenario and is not limited here.

[0043] The inverter provided in this application can be adapted to high-power inverter application scenarios and small and medium-power inverter application scenarios, such as photovoltaic power supply application scenarios, wind power grid-connected power supply scenarios, electric vehicle charging scenarios or other application scenarios. The photovoltaic power supply application scenario will be used as an example for explanation, and no further details will be given below. Please refer to Figure 1 , Figure 1 Schematic diagram of the application scenario of the inverter provided in this application. 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, wherein the photovoltaic array can be connected to the input end of the DC / DC converter, the output end of the DC / DC converter can be connected to the input end of the inverter through the positive DC bus and the negative DC bus, and the output end of the inverter can be used to connect to the power grid. The photovoltaic array here can be composed of a plurality of photovoltaic strings connected in series and parallel, wherein one photovoltaic string can include a plurality of photovoltaic modules (also referred to as solar panels or photovoltaic panels), and the inverter includes a power module and n cooling fans. In the process of the photovoltaic system supplying power to the AC power 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 power grid.

[0044] In this power supply process, since n cooling fans will cool and dissipate the heat generated by the power module, it is particularly important to accurately control the speed of the n cooling fans. In the process of controlling the speed of the n cooling fans, the controller in the inverter (not shown) can detect the first temperature when the power module outputs the first signal and the second temperature when the power module outputs the second signal, wherein each of the first signal and the second signal includes output power or output current, and the detection time of the first temperature is before the detection time of the second temperature. Further, the controller can adjust the target fan duty cycle according to the second signal, the change between the first signal and the second signal, and the change between the first temperature and the second temperature to quickly control the speed of each cooling fan in the n cooling fans, which can reduce the number of temperature cycles (can be referred to as the number of temperature cycles) and the temperature cycle amplitude (can also be referred to as the temperature fluctuation amplitude) of the power module, thereby effectively suppressing the temperature cycle of the power module to improve the safety and reliability of the power module, further improving the power supply reliability and power supply safety of the inverter, and having strong applicability.

[0045] The following will be combined Figures 2 to 8 The inverter, photovoltaic system and their working principles provided in this application are illustrated.

[0046] See also Figure 2 , Figure 2 Schematic diagram of the structure of the inverter provided by this application. Figure 2 As shown, the 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 the cooling fans 15a to 15n can constitute a cooling system in the inverter 1. The input port 12 is used to receive a DC input signal. For example, the DC input signal can be Figure 1The output port is used to output a first signal and a second signal, wherein the first signal and the second signal can be provided by the power module 11.

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

[0048] In some feasible implementations, the temperature detection device 14 may be disposed outside the controller 10, and optionally, the temperature detection device 14 may also be disposed inside the controller 10. The temperature detection device 14 includes, but is not limited to, at least one temperature-sensitive device selected from the group consisting of a thermocouple, a positive temperature coefficient (PTC) thermistor, a negative temperature coefficient (NTC) thermistor, a silicon resistance temperature sensor, and an IC temperature sensor, wherein the positive temperature coefficient thermistor may be referred to as a PTC thermistor, and the negative temperature coefficient thermistor may be referred to as an NTC thermistor.

[0049] In some feasible implementations, 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, thereby ensuring the real-time and accuracy of the 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 carry the power module 11, and the heat sink is used to dissipate the heat of the power module 11. The power board and the heat sink are Figure 2 Not shown. The above-mentioned first temperature or second temperature can be understood as the temperature of the power module 11, and the first temperature or the 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 radiator. The above-mentioned temperature detection device 14 can establish wired communication or wireless communication with the controller 10 to transmit temperature data. For example, the temperature data includes a first temperature and a second temperature. For the convenience of description, the following will be explained as an example in which the first temperature or the second temperature includes the temperature of the power module 11, and no further details will be given below. 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 embodiments, the controller 10 adjusts the target fan duty cycle according to the second signal, the change between the first signal and the second signal, and the change between the first temperature and the second temperature to control the speed of each cooling fan in the cooling fan 15a to the cooling fan 15n. At this time, each cooling fan is used to operate according to the speed of each cooling fan to dissipate heat for the power module 11. Since the first signal, the second signal, the first temperature and the second temperature are all real-time detection data, that is, the change between the first signal and the second signal and the change between the first temperature and the second temperature are real-time changes, the controller 10 can dynamically adjust the target fan duty cycle according to the real-time detection data and the real-time change to quickly control the speed of each cooling fan, 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 of the power module; in addition, the life loss of the power module is reduced, and the reliability of the power module is improved, and the applicability is strong. The temperature cycle here can be understood as the ambient temperature cycle of the inverter 1 in different natural environments at different time scales.

[0051] In some feasible embodiments, the amount of 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 time difference. Among them, 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, and the change direction includes positive increase or negative decrease. The detection time difference is the difference between the detection time of the first temperature and the detection time of the second temperature, and the detection time difference is greater than 0. In the case where the first temperature is greater than the second temperature, the difference and the rate of change between the first temperature and the second temperature are less than 0, and the direction of change between the first temperature and the second temperature is negative decrease, that is, the temperature change trend of the power module 11 is negative decrease. In the case where the first temperature is less than the second temperature, it can be obtained that the difference and the rate of change between the first temperature and the second temperature are greater than 0, and the direction of change between the first temperature and the second temperature is positive increase, that is, the temperature change trend of the power module 11 is positive increase.

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

[0053] In some feasible embodiments, the controller 10 can detect the operating status of the inverter 1 in real time, wherein 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, thereby ensuring the accuracy and real-time performance of temperature detection and output signal detection, and having strong applicability.

[0054] In some feasible implementations, after detecting the operating state of the inverter 1, the controller 10 may obtain the first duty cycle parameter d based on the second signal and the second temperature. 1 Among them, the first duty cycle parameter d 1 It can be understood as the fan speed control quantity, and the first duty cycle parameter d 1 Specifically, the controller 10 outputs a first duty cycle parameter d based on the monotonic mapping relationship between the second temperature and the second signal and the fan speed. 1 , that is, the input parameters of the monotonic mapping relationship are the second temperature and the second signal, and the output parameter of the monotonic mapping relationship is the first duty cycle parameter d 1 The implementation of the monotonic mapping relationship includes but is not limited to a function, a formula, a chart or a curve; and the monotonic mapping relationship can be expressed as follows: when the temperature of the power module 11 increases or the output signal of the power module 11 increases, the first duty cycle parameter d 1 when the temperature of the power module 11 decreases or the output signal of the power module 11 decreases, the first duty cycle parameter d 1 Reduce.

[0055] Optionally, the controller 10 may also obtain a first duty cycle parameter d based on the second signal. 11 , and obtain another first duty cycle parameter d based on the second temperature 12 , where the first duty cycle parameter d 11 and the first duty cycle parameter d 12 It can be understood as the fan speed control quantity, 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 To reflect the steady-state adjustment amount of the fan speed associated with the second temperature. For the convenience of description, the first duty cycle parameter d 1 This is explained by taking an example and will not be described in detail below.

[0056] In some feasible implementations, the controller 10 obtains the second duty cycle parameter d based on the change between the first signal and the second signal. 2 , and obtain a third duty cycle parameter d based on the change between the first temperature and the second temperature 3 Among them, the second duty cycle parameter d 2 It can be understood as the fan speed control quantity, and the second duty cycle parameter d 2In order to reflect the dynamic adjustment amount of the fan speed, the influence of sudden changes in light and load on the number and amplitude of the temperature cycle of the power module 11 can be reduced, thereby reducing the number and amplitude of the temperature cycle of the power module 11 and effectively suppressing the temperature cycle of the power module 11. The third duty cycle parameter d 3 It can be understood as the fan speed control quantity, and the third duty cycle parameter d 3 In order to reflect the dynamic adjustment amount of the fan speed, the influence of the start and stop of the cooling fan and the ambient temperature on the number and amplitude of the temperature cycle of the power module 11 can be reduced, thereby reducing the temperature cycle amplitude of the power module 11 in the power fluctuation scenario, that is, avoiding large fluctuations in the temperature cycle amplitude of the power module 11 in the power fluctuation scenario.

[0057] Specifically, the controller 10 may further output a second duty cycle parameter d based on a monotonic mapping relationship between the variation between the first signal and the second signal and the fan speed. 2 , that is, the input parameter of the monotonic mapping relationship is the change between the first signal and the second signal, and the output parameter of the monotonic mapping relationship is the second duty cycle parameter d 2 The implementation of the monotonic mapping relationship may include but is not limited to a function, a formula, a chart or a curve; and the monotonic mapping relationship may be expressed as follows: when the output change trend of the power module 11 is positively increasing, the second duty cycle parameter d 2 When the output change trend of the power module 11 is negatively decreasing, the second duty cycle parameter d 2 For example, when the monotonic mapping relationship is a differential formula, the second duty cycle parameter d 2 It is a value obtained by differentiating the change between the first signal and the second signal. It should be noted that the specific implementation method of the monotonic mapping relationship can be determined according to the actual application scenario and is not limited here.

[0058] Furthermore, the controller 10 may also output a third duty cycle parameter d based on a monotonic mapping relationship between the change amount between the first temperature and the second temperature and the fan speed. 3 , that is, the input parameter of the monotonic mapping relationship is the change between the first temperature and the second temperature, and the output parameter of the monotonic mapping relationship is the third duty cycle parameter d 3 The implementation of the monotonic mapping relationship may include but is not limited to a function, a formula, a chart or a curve; and the monotonic mapping relationship may be expressed as follows: when the temperature change trend of the power module 11 is positively increasing, the third duty cycle parameter d 3 When the temperature change trend of the power module 11 is negative, the third duty cycle parameter d 3 For example, when the monotonic mapping relationship is an integral formula, the third duty cycle parameter d 3It is a value obtained by integrating the change between the first temperature and the second temperature. It should be noted that the specific implementation method of the 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 may be configured to provide a first duty cycle parameter d 1 , the second duty cycle parameter d 2 And the third duty cycle parameter d 3 Adjust the target fan duty cycle d out Since the first duty cycle parameter d 1 is the steady-state adjustment value reflecting the fan speed, and the second duty cycle parameter d 2 and the third duty cycle parameter d 3 To reflect the dynamic adjustment of fan speed, the target fan duty cycle d out It can simultaneously reflect the steady-state adjustment amount and dynamic adjustment amount of the fan speed, thereby increasing the target fan duty cycle d out At this time, the controller 10 is based on the target fan duty cycle d out Controlling the rotation 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, thereby improving the safety of the power module 11 and having strong applicability.

[0060] Specifically, the controller 10 can also obtain the first duty cycle parameter d 1 , the second duty cycle parameter d 2 And the third duty cycle parameter d 3 The weighted coefficient of each duty cycle parameter in the target fan duty cycle d is adjusted based on each duty cycle parameter and its weighted coefficient. out The weighting coefficient may be greater than or equal to 0 and less than or equal to 1. The weighting coefficient may be a preset parameter of the inverter 1 at the factory, a parameter set by the user, or a parameter dynamically adjusted according to the specific working condition of the inverter 1. The specific weighting coefficient may be determined according to the actual application scenario and is not limited here. out It can be a value obtained by weighted summing of each duty cycle parameter and its weighted coefficient. It can be understood that the controller 10 can flexibly control the proportion of each duty cycle parameter through the weighted coefficient, thereby reducing the number of temperature cycles and the temperature cycle amplitude of the power module 11 to suppress the temperature cycle of the power module 11, improving the safety of the power module 11, and having strong applicability.

[0061] In some feasible implementations, when adjusting the target fan duty cycle d out Afterwards, the controller 10 sets the target fan duty cycle d outWhen the duty cycle is less than the preset threshold value, the speed of a part of the cooling fans 15a to 15n is controlled to be 0, and the speed of the other part of the cooling fans is controlled to be the first speed. The number of the other part of the cooling fans and the first speed are determined by the second temperature and the second signal, and the first speed is less than the preset speed threshold; and the number of the other part of the cooling fans can be understood as the number of cooling fans in operation, the number of the other part of the cooling fans can be expressed as N and N≥1, and the first speed can be understood as the operating speed of the cooling fans. The preset duty cycle threshold here is a parameter configured by the inverter 1 at the factory or a parameter set by the user, and the preset speed threshold refers to the maximum speed value of the cooling fan running in the low speed section. When the speed of a part of the cooling fans is 0, it can be obtained that a part of the cooling fans are not running; when the speed of the other part of the cooling fans is the first speed, it can be obtained that the other part of the cooling fans are running in the low speed section.

[0062] It can be understood that at the target fan duty cycle d out When the duty cycle is less than the preset threshold, the controller 10 will flexibly control the number and speed of operation of the cooling fan in the low speed section. For example, by flexibly controlling different combinations of the number and speed of operation of the cooling fan, the cooling 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 number of temperature cycles of the power module 11, and at the same time greatly reducing the loss of the inverter 1, making it more applicable.

[0063] For the convenience of description, the cooling fan 15a, the cooling fan 15b and the cooling fan 15n are taken as examples for explanation. The different operation quantity combinations corresponding to each cooling fan in the cooling fan 15a, the cooling fan 15b and the cooling fan 15n can be expressed as 011, 101, 110 or 010, where 1 can indicate that the rotation speed of the cooling fan is the first rotation speed, that is, the cooling fan is running at the first rotation speed; 0 can indicate that the rotation speed of the cooling fan is 0, that is, the cooling fan is not running. For example, when the different operation quantity combinations corresponding to each cooling fan are 011, the cooling fan 15a is not running, the cooling fan 15b is running at the first rotation speed, and the cooling fan 15n is running at the first rotation speed. The different operation speed combinations corresponding to each cooling fan can be expressed as (D1-D2-D3), where D1 is used to indicate the rotation speed of the cooling fan 15a, D2 is used to indicate the rotation speed of the cooling fan 15b, and D3 is used to indicate the rotation speed of the cooling fan 15n, and any one of D1, D2 and D3 is 0 or the first rotation speed.

[0064] In some feasible implementations, the controller 10 may set the target fan duty cycle d out If the fan duty cycle is greater than or equal to the preset duty cycle threshold, the fan duty cycle is set to the target fan duty cycle d outThe speed of cooling fan 15a to cooling fan 15n is controlled to be a second speed. The second speed is greater than the first speed, and the second speed refers to any speed value of the cooling fan running in the high speed section. The second speed here can be determined by the target fan duty cycle d out , the second temperature and the second signal. It can be understood that the target fan duty cycle d out When the duty cycle is greater than or equal to the preset threshold value, the controller 10 controls all cooling fans to run simultaneously to quickly dissipate heat from the power module 11, thereby improving the cooling efficiency of the inverter 1 and having strong applicability. out The duty cycle threshold is compared with the preset duty cycle threshold, and the cooling fans 15a to 15n are flexibly controlled to operate in the low speed section or the high speed section according to the comparison result, thereby widening the working range of the cooling system to improve the cooling efficiency and making it more applicable.

[0065] For the convenience of description, the following description will be made by taking the first signal and the second signal as output power as an example. In one embodiment, the controller 10 determines the target fan duty cycle d based on the target fan duty cycle d. out Control the speed of each cooling fan in cooling fan 15a to cooling fan 15n, wherein the speed can be 0, the first speed or the second speed. At this time, the effect of suppressing the temperature cycle of power module 11 can be seen in Figure 3A , Figure 3A 1 is a schematic diagram of an effect of suppressing the temperature cycle of the power module provided by the present application. In another embodiment, the controller 10 obtains the fan duty ratio only according to the current temperature of the power module 11, and controls the speed of each cooling fan from the cooling fan 15a to the cooling fan 15n according to the fan duty ratio. At this time, the effect of suppressing the temperature cycle of the power module 11 can be seen in Figure 3B , Figure 3B This is another schematic diagram of the effect of suppressing the temperature cycle of the power module provided by the present application.

[0066] contrast Figure 3A and Figure 3B The effect diagram shown in the figure shows that, when the power change trend is consistent, Figure 3A The fluctuation range and fluctuation amplitude of the temperature of the power module 11 shown are smaller, so the controller 10 sets the target fan duty cycle d out Controlling the rotation speed of each cooling fan can quickly reflect the power change trend and temperature change trend, effectively suppressing the temperature cycle number and temperature cycle amplitude of the power module 11, thereby improving the reliability of the inverter 1 and reducing the market failure rate of the inverter 1.

[0067] In some feasible implementations, the specific structure of the inverter 1 can also be found in Figure 4 , Figure 4is another structural schematic diagram of the inverter provided by the present application. Figure 4 As shown, the power module 11 includes power units 110a to 110m. Figure 2 The inverter 1 shown also includes a heat sink 16 and silicone grease 17a to 17m. The power units 110a to 110m can be installed on the surface of the heat sink 16 respectively, and silicone grease is provided between each of the power units 110a to 110m and the heat sink 16. For example, silicone grease 17a is provided between the power unit 110a and the heat sink 16, silicone grease 17b is provided between the power unit 110b and the heat sink 16, ..., silicone grease 17m is provided between the power unit 110m and the heat sink 16. The power units 110a to 110m, the cooling fans 15a to 15n, the heat sink 16, and the silicone grease 17a to 17m here can constitute a heat dissipation system in the inverter 1, and the heat dissipation system also includes but is not limited to heat pipes and air ducts. The number and arrangement positions of various types of components in the heat dissipation system can be determined by the specific type of the above-mentioned inverter 1, and are not limited here. Among them, the heat pipe is a heat transfer element, and the air duct refers to a channel for air circulation built with concrete, bricks and other materials.

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

[0069] In some feasible implementations, in order to quickly dissipate heat for the power module 11, the controller 10 may control the speed of each cooling fan from the cooling fan 15a to the cooling fan 15n in real time. 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 arranged outside the controller 10. Wherein, when the output signal of the power module 11 is the 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 the output current, the output signal sampling unit 101 may include but is not limited to a current detection circuit or an ammeter.

[0070] In some feasible implementations, wired or wireless communication can be established between the temperature detection device 14 and the output signal sampling unit 101 and the fan speed control unit 102, so as to transmit temperature data and signal data. In the process of controlling the rotation 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 temperature and the second temperature to the fan speed control unit 102; the output signal sampling unit 101 can detect the first signal and the second signal output by the power unit 110a to the power unit 110m through the output port 13, and output the first signal and the second signal to the fan speed control unit 102.

[0071] Further, the fan speed control unit 102 may adjust the target fan duty cycle d 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. out The duty cycle instruction is generated and output to the cooling fans 15a to 15n, thereby controlling the speed of each cooling fan in the cooling fans 15a to 15n. The duty cycle instruction may also be referred to as a fan speed control instruction. The duty cycle instruction includes a target fan duty cycle d out The specific calculation process can be found in the above Figure 2 In the corresponding embodiment, the target fan duty cycle d out After obtaining the duty cycle instruction, each cooling fan from cooling fan 15a to cooling fan 15n can operate according to the duty cycle instruction to dissipate heat for power module 11, thereby reducing the temperature fluctuation of radiator 16 and power module 11, effectively suppressing the temperature cycle of power module 11, and having strong applicability.

[0072] In the inverter 1 provided in the present application, the controller 10 can dynamically adjust the target fan duty cycle 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 quickly control the rotation speed of each cooling fan, which can reduce the number of temperature cycles and the temperature cycle amplitude of the power module 11, thereby improving the safety of the power module 11; in addition, it also reduces the life loss of the power module 11 and improves the reliability of the power module 11. Further, the controller 10 can adjust the target fan duty cycle d out The duty cycle threshold is compared with the preset duty cycle threshold, and the cooling fans 15a to 15n are flexibly controlled to operate in the low speed section or the high speed section according to the comparison result, thereby widening the working range of the cooling system to improve the cooling efficiency and making it more applicable.

[0073] The following is an example of a photovoltaic system including an inverter. Please refer to Figure 5, Figure 5 Schematic diagram of a photovoltaic system provided by this application. Figure 5 As shown, the photovoltaic system 2 includes a photovoltaic array 20 and an inverter 30 (such as the inverter 1 described above) connected to the photovoltaic array 20 (such as directly connected or indirectly connected), and the output end of the inverter 30 can be connected (such as directly connected or indirectly connected) to the AC power grid. In 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 an AC voltage, and supply power to the AC power grid based on the AC voltage. In the case where 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 power supply safety of the inverter 30 are higher, thereby improving the power supply efficiency and power supply safety of the photovoltaic system 2, and having strong adaptability.

[0074] In some feasible implementations, the specific structure of the photovoltaic system 2 can also be found in Figure 6 , Figure 6 is another schematic diagram of the structure of the photovoltaic system provided by this application. Figure 6 As shown, the photovoltaic system 2 further includes a DC combiner box 40, and the photovoltaic array 20 can be connected to the input end of the inverter 30 through the DC combiner box 40, and the output end of the inverter 30 can be connected (such as directly or indirectly) to the AC power grid. In the process of supplying power to the AC power grid, the DC combiner box 40 can combine the DC voltage provided by each photovoltaic string in the photovoltaic array 20 and output it to the inverter 30. At this time, the inverter 30 (such as a centralized photovoltaic inverter) can supply power to the AC power grid based on the combined DC voltage. In this power supply process, since the power supply reliability and power supply safety of the inverter 30 are higher, the power supply efficiency and power supply safety of the photovoltaic system 2 can be improved, and the adaptability is stronger.

[0075] Optional, such as Figure 6 As shown, the photovoltaic system 2 also includes a box-type transformer 50, and the output end of the inverter 30 can be connected to the AC power grid through the box-type transformer 50, wherein 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 certain wiring scheme and is installed in a box-type housing. In the process of supplying power to the AC power grid, the inverter 30 (such as a centralized photovoltaic inverter) can output an AC voltage to the box-type transformer 50 based on the DC voltage after converging. At this time, the box-type transformer 50 can supply power to the AC power grid based on the AC voltage input by the inverter 30. In this power supply process, since the power supply reliability and power supply safety of the inverter 30 are higher, the power supply efficiency and power supply safety of the photovoltaic system 2 can be improved, and the adaptability is stronger.

[0076] In some feasible implementations, the specific structure of the photovoltaic system 2 can also be found in Figure 7 , Figure 7 is another schematic diagram of the structure of the photovoltaic system provided by this application. 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 end of the AC combiner box 60 through the inverter 30, and the output end of the AC combiner box 60 can be connected (such as directly or indirectly) to the AC power grid. In the process of supplying power to the AC power grid, the inverter 30 can provide an AC voltage to the AC combiner box 60 based on the DC voltage provided by the photovoltaic array 20, and the AC combiner box 60 can supply power to the AC power grid with the AC voltage input by the inverter 30 (such as a string photovoltaic inverter). In this power supply process, since the power supply reliability and power supply safety of the inverter 30 are higher, the power supply efficiency and power supply safety of the photovoltaic system 2 can be improved, and the adaptability is stronger.

[0077] Optional, such as Figure 7 As shown, the photovoltaic system 2 further includes a box-type transformer 51, and the output end of the AC combiner box 60 can be connected to the AC grid through the box-type transformer 51. In the process of supplying power to the AC grid, the AC combiner box 60 can combine the AC voltage input by 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 grid based on the combined AC voltage. In this power supply process, since the power supply reliability and power supply safety of the inverter 30 are higher, the power supply efficiency and power supply safety of the photovoltaic system 2 can be improved, and the adaptability is stronger.

[0078] In some feasible implementations, the specific structure of the photovoltaic system 2 can also be found in Figure 8 , Figure 8 is another schematic diagram of the structure of the photovoltaic system provided by this application. Figure 8 As shown above Figure 5 The photovoltaic system 2 shown in the figure also includes a DC / DC converter 70 and a DC bus 80. The photovoltaic array 20 can be connected to the input end of the inverter 30 through the DC / DC converter 70 and the DC bus 80. The output end of the inverter 30 can be connected to the AC power grid. The DC bus 80 can include a positive DC bus and a negative DC bus (such as Figure 1The positive DC bus and negative DC bus shown in the figure). In 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 an AC voltage, and supply power to the AC grid based on the AC voltage. In this power supply process, since the power supply reliability and power supply safety of the inverter 30 are higher, the power supply efficiency and power supply safety of the photovoltaic system 2 can be improved, and the adaptability is stronger.

[0079] In the photovoltaic system 2 provided in the present application, since the power supply reliability and power supply safety of the above-mentioned inverter 30 are higher, the power supply efficiency and power supply safety of the photovoltaic system 2 can be improved, and the system power supply flexibility and adaptability are stronger.

[0080] The following is an example of how to adjust the speed of the inverter cooling fan. Fig. 9 , Fig. 9 The present invention provides a flow chart of a method for adjusting the speed of an inverter cooling fan. The method is applicable to an inverter (such as the above Figures 2 to 4 The controller in the inverter 1) shown in FIG. 1 further includes a power module and at least one cooling fan. Fig. 9 As shown, the method includes the following steps S101 to S102:

[0081] Step S101 , detecting a first temperature when a power module outputs a first signal and a second temperature when the power module outputs a second signal.

[0082] In some feasible embodiments, each of the above-mentioned first signal and second signal 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 temperature and the second temperature of the power module through a temperature detection device, so as to ensure the accuracy and real-time performance of temperature sampling. The temperature detection device here may include but is not limited to: a thermocouple, a positive temperature coefficient thermistor, a negative temperature coefficient thermistor, a silicon resistance temperature sensor, an IC temperature sensor or other temperature-sensitive devices. Among them, the first temperature or the second temperature can be understood as the temperature of the inverter, and the first temperature or the 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 radiator. For the convenience of description, the first temperature or the second temperature including the temperature of the power module will be used as an example for explanation below, and no further details will be given below. At this time, 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 temperature and the second temperature of the power module through a temperature detection device, and detect the first signal and the second signal of the power module, thereby completing the real-time detection process of the operating state of the inverter. In one embodiment, when each of the first signal and the second signal is output power, the controller can detect the first output power and the second output power of the power module through 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 is an output current, the controller can detect the first output current and the second output current of the power module through a current detection circuit or an ammeter, thereby ensuring the accuracy and real-time performance of current sampling.

[0084] Step S102, adjusting the target fan duty cycle according to the second signal, the variation between the first signal and the second signal, the second temperature, and the variation between the first temperature and the second temperature to control the rotation speed of each cooling fan in at least one cooling fan.

[0085] In some feasible embodiments, the amount of 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 time difference. Among them, 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, and the change direction includes positive increase or negative decrease. The detection time difference is the difference between the detection time of the first temperature and the detection time of the second temperature, and the detection time difference is greater than 0. In the case where the first temperature is greater than the second temperature, the difference and the rate of change between the first temperature and the second temperature are less than 0, and the direction of change between the first temperature and the second temperature is negative decrease, that is, the temperature change trend of the power module is negative decrease. In the case where the first temperature is less than the second temperature, it can be obtained that the difference and the rate of change between the first temperature and the second temperature are greater than 0, and the direction of change between the first temperature and the second temperature is positive increase, that is, the temperature change trend of the power module is positive increase.

[0086] In some feasible embodiments, the amount of change between the first signal and the second signal includes but is not limited to at least one of the difference, change rate, change direction, and time difference between the first signal and the second signal. Among them, the change rate is the ratio between the difference between the first signal and the second signal and the time difference. The change direction is the output change trend of the power module, which includes positive increase or negative decrease. When each of the first signal and the second signal is the output power, the output change trend of the power module is the power change trend; when each of the first signal and the second signal is the output current, the output change trend of the power module is the 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 change rate between the first signal and the second signal are less than 0, and the change direction between the first signal and the second signal is negative decrease, that is, the output change trend of the power module is negative decrease. When the first signal is less than the second signal, the difference and change rate between the first signal and the second signal are greater than 0, and the change direction between the first signal and the second signal is positive increase, that is, the output change trend of the power module is positive increase.

[0087] In some feasible implementations, the operations performed by the controller in the process of controlling the speed of each cooling fan can be seen in Fig.10 , Fig.10 FIG. 1 is another flow chart of the speed regulation method of the inverter cooling fan provided by the present application. Fig.10 As shown, the method includes the following steps S1021 to S1026:

[0088] Step S1021, obtaining a first duty cycle parameter d based on the second signal and the second temperature 1 .

[0089] In some feasible implementations, the controller may output a first duty cycle parameter d based on a monotonic mapping relationship between the second signal and the second temperature and the fan speed. 1 , that is, the input parameters of the monotonic mapping relationship are the second temperature and the second signal, and the output parameter of the monotonic mapping relationship is the first duty cycle parameter d 1 The implementation of the monotonic mapping relationship includes but is not limited to a function, a formula, a chart or a curve; and the monotonic mapping relationship may 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 d 1 Increase; when the temperature of the power module decreases or the output signal of the power module decreases, the first duty cycle parameter d 1 Decrease. Among them, the first duty cycle parameter d 1 It can be understood as the fan speed control quantity, and the first duty cycle parameter d1 It reflects the steady-state adjustment value of the fan speed.

[0090] Optionally, the controller may also obtain a first duty cycle parameter d based on the second signal. 11 , and obtain another first duty cycle parameter d based on the second temperature 12 , where the first duty cycle parameter d 11 and the first duty cycle parameter d 12 It can be understood as the fan speed control quantity, 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 To reflect the steady-state adjustment amount of the fan speed associated with the second temperature. For the convenience of description, the first duty cycle parameter d 1 This is explained by taking an example and will not be described in detail below.

[0091] Step S1022, obtaining a second duty cycle parameter d based on the change between the first signal and the second signal 2 .

[0092] Specifically, the controller may further output a second duty cycle parameter d based on a monotonic mapping relationship between the variation between the first signal and the second signal and the fan speed. 2 , that is, the input parameter of the monotonic mapping relationship is the change between the first signal and the second signal, and the output parameter of the monotonic mapping relationship is the second duty cycle parameter d 2 The implementation of the monotonic mapping relationship may include but is not limited to a function, a formula, a chart or a curve; and the monotonic mapping relationship may be expressed as follows: when the output change trend of the power module is positively increasing, the second duty cycle parameter d 2 Increase; when the output change trend of the power module is negative, the second duty cycle parameter d 2 For example, when the monotonic mapping relationship is a differential formula, the second duty cycle parameter d 2 It is a value obtained by differentiating the change between the first signal and the second signal. It should be noted that the specific implementation method of the monotonic mapping relationship can be determined according to the actual application scenario and is not limited here.

[0093] Among them, the second duty cycle parameter d 2 It can be understood as the fan speed control quantity, and the second duty cycle parameter d 2 In order to reflect the dynamic adjustment amount of the fan speed, the influence of sudden changes in light and load on the number and amplitude of temperature cycles of the power module can be reduced, thereby reducing the number and amplitude of temperature cycles of the power module and effectively suppressing the temperature cycle of the power module.

[0094] Step S1023, obtaining a third duty cycle parameter d based on the change between the first temperature and the second temperature 3 .

[0095] Specifically, the controller may further output a third duty cycle parameter d based on a monotonic mapping relationship between the change amount between the first temperature and the second temperature and the fan speed. 3 , that is, the input parameter of the monotonic mapping relationship is the change between the first temperature and the second temperature, and the output parameter of the monotonic mapping relationship is the third duty cycle parameter d 3 The implementation of the monotonic mapping relationship may include but is not limited to a function, a formula, a chart or a curve; and the monotonic mapping relationship may be expressed as follows: when the temperature change trend of the power module is positively increasing, the third duty cycle parameter d 3 Increase; when the temperature change trend of the power module is negative, the third duty cycle parameter d 3 For example, when the monotonic mapping relationship is an integral formula, the third duty cycle parameter d 3 It is a value obtained by integrating the change between the first temperature and the second temperature. It should be noted that the specific implementation method of the monotonic mapping relationship can be determined according to the actual application scenario and is not limited here.

[0096] Among them, the third duty cycle parameter d 3 It can be understood as the fan speed control quantity, and the third duty cycle parameter d 3 In order to reflect the dynamic adjustment amount of the fan speed, the influence of the start and stop of the cooling fan and the ambient temperature on the number and amplitude of the temperature cycle of the power module can be reduced, thereby reducing the temperature cycle amplitude of the power module in the power fluctuation scenario, that is, avoiding the large fluctuation of the temperature cycle amplitude of the power module in the power fluctuation scenario.

[0097] Step S1024: based on the first duty cycle parameter d 1 , the second duty cycle parameter d 2 And the third duty cycle parameter d 3 Adjust the target fan duty cycle d out .

[0098] Among them, since the first duty cycle parameter d 1 is the steady-state adjustment value reflecting the fan speed, and the second duty cycle parameter d 2 and the third duty cycle parameter d 3 To reflect the dynamic adjustment of fan speed, the target fan duty cycle d out It can simultaneously reflect the steady-state adjustment amount and dynamic adjustment amount of the fan speed, thereby increasing the target fan duty cycle d out accuracy.

[0099] Specifically, the controller can also obtain a first duty cycle parameter d 1 , the second duty cycle parameter d 2 And the third duty cycle parameter d 3 The weighted coefficient of each duty cycle parameter in the target fan duty cycle d is adjusted based on each duty cycle parameter and its weighted coefficient. out The weighting coefficient may be greater than or equal to 0 and less than or equal to 1. The weighting coefficient may be a preset parameter of the inverter factory setting, a parameter set by the user, or a parameter dynamically adjusted according to the specific working conditions of the inverter. The specific parameters may be determined according to the actual application scenario and are not limited here. out It can be a value obtained by weighted summing of each duty cycle parameter and its weighted coefficient. It can be understood that the controller can flexibly control the proportion of each duty cycle parameter through the weighted coefficient, thereby reducing the number of temperature cycles and the temperature cycle amplitude of the power module to suppress the temperature cycle of the power module, improving the safety of the power module and having strong applicability.

[0100] Step S1025: at the target fan duty cycle d out When the duty cycle is less than a preset duty cycle threshold, the rotation speed of a part of the at least one cooling fan is controlled to be 0, and the rotation speed of another part of the cooling fans is controlled to be the first speed.

[0101] Among them, the number of the other part of the cooling fans and the first speed are determined by the second temperature and the second signal, and the first speed is less than the preset speed threshold; and the number of the other part of the cooling fans can be understood as the number of cooling fans in operation, the number of the other part of the cooling fans can be expressed as N and N ≥ 1, and the first speed can be understood as the operating speed of the cooling fans. The preset duty cycle threshold here is the parameter configured by the inverter at the factory or the parameter set by the user, and the preset speed threshold refers to the maximum speed value of the cooling fan running in the low-speed section. When the speed of one part of the cooling fans is 0, it can be obtained that one part of the cooling fans is not running; when the speed of another part of the cooling fans is the first speed, it can be obtained that the other part of the cooling fans are running in the low-speed section.

[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 fan in the low-speed section. For example, flexible control of different combinations of operating numbers and different operating speeds can expand the cooling efficiency range of the cooling system in the inverter, that is, improve the equivalent efficiency adjustment range of the cooling system, thereby effectively suppressing the number of temperature cycles of the power module, while greatly reducing the loss of the inverter, and making it more applicable.

[0103] Step S1026: at the target fan duty cycle d outWhen the duty cycle is greater than or equal to a preset duty cycle threshold, the rotation speed of at least one cooling fan is controlled to be a second rotation 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 running in the high speed section. The second speed here can be determined by the target fan duty cycle d out , the second temperature and the second signal. At the target fan duty cycle d out When the duty cycle is greater than or equal to the preset threshold, the controller will control all cooling fans to run simultaneously to quickly dissipate heat from the power module, thereby improving the cooling efficiency of the inverter and having strong applicability. out The duty cycle threshold is compared with the preset duty cycle threshold, and at least one cooling fan is flexibly controlled to operate in a low speed section or a high speed section according to the comparison result, thereby broadening the working range of the cooling system to improve the cooling efficiency and making it more applicable.

[0105] In a specific implementation, more operations performed by the controller in the speed regulation method of the inverter cooling fan provided in the present application can be found in the above Figures 2 to 4 The inverter 1 shown and the implementation method performed by the controller 10 in its working principle are not described in detail here.

[0106] In the method provided in the present application, the controller can dynamically adjust the target fan duty cycle 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 quickly control the rotation speed of each cooling fan, which can reduce the number of temperature cycles and the temperature cycle amplitude of the power module, thereby improving the safety of the power module; in addition, the life loss of the power module is reduced and the reliability of the power module is improved. Furthermore, 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 in the low speed section or the high speed section according to the comparison result, so as to broaden the working range of the cooling system to improve the cooling efficiency, and the applicability is stronger.

[0107] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection 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 radiator is used to dissipate heat from the power module; The power module is used to perform AC-DC conversion on the DC input signal to output power or output current; The temperature detection device is used to detect a first temperature when the power module outputs power or outputs current at a first moment and a second temperature when the power module outputs power or outputs current at a second moment, and the first moment when the first temperature is detected is before the second moment when the second temperature is detected; The controller is used to adjust the target fan duty cycle according to the output current or output power at the second moment, the change between the output current or output power at the first moment and the output current or output power at the second moment, the second temperature, and the change between the first temperature and the second temperature, so as to control the rotation speed of each cooling fan of the at least one cooling fan to dissipate heat for the power module; The first temperature or the second temperature includes: a temperature of the power module, an internal air temperature of the inverter, a temperature of the power board, or a 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 difference, change rate, change direction, and time difference between the output current or output power at the first moment and the output current or output power at the second moment; the change between the first temperature and the second temperature includes at least one of the difference, change rate, change direction, and detection time difference between the first temperature and the second temperature.

3. The inverter according to any one of claims 1 or 2, characterized in that: The controller is used to: Obtaining a first duty cycle parameter based on the output current or output power at the second moment and the second temperature; Obtaining a second duty cycle parameter based on a change between the output current or output power at the first moment and the output current or output power at the second moment, and obtaining a third duty cycle parameter based on a change between the first temperature and the second temperature; The target fan duty cycle 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 to: Obtain a weighted coefficient of each of 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 of the duty cycle parameters and their weighted coefficients, wherein the weighted coefficient is greater than or equal to 0 and less than or equal to 1.

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

6. A speed regulation method for an inverter cooling fan, characterized in that: The method is applicable to a controller in an inverter, wherein the inverter further includes a power module and at least one cooling fan; the method includes: Detecting a first temperature when the power module outputs an output current or output power at a first moment and a second temperature when the power module outputs an output current or output power at a second moment, wherein each signal of the output current or output power at the first moment and the output current or output power at the second moment includes output power or output current, and the detection time of the first temperature is before the detection time of the second temperature; The target fan duty cycle is adjusted according to the output current or output power at the second moment, the change between the output current or output power at the first moment and the output current or output power at the second moment, the second temperature, and the change between the first temperature and the second temperature to control the rotation speed of each cooling fan of the at least one cooling fan.

7. The method according to claim 6, characterized in that 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 temperature or the second temperature includes: a temperature of the power module, an internal air temperature of the inverter, a temperature of the power board, or a temperature of the heat sink.

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 difference, change rate, change direction, and time difference between the output current or output power at the first moment and the output current or output power at the second moment; the change between the first temperature and the second temperature includes at least one of the difference, change rate, change direction, and detection time difference between the first temperature and the second temperature.

9. The method according to claim 7 or 8, characterized in that: The step of adjusting the target fan duty cycle according to the output current or output power at the second moment, the change between the output current or output power at the first moment and the output current or output power at the second moment, the second temperature, and the change between the first temperature and the second temperature includes: obtaining a first intermediate fan duty cycle based on the output current or output power at the second moment and the second temperature; Obtaining a second intermediate fan duty cycle based on a change between the output current or output power at the first moment and the output current or output power at the second moment, and obtaining a third intermediate fan duty cycle based on a change between the first temperature and the second temperature; A target fan duty cycle is adjusted 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 a weighted coefficient 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 weighted coefficient, wherein the weighted coefficient is greater than or equal to 0 and less than or equal to 1.

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

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