Inverter and inverter protection method

Abstract

The invention provides an inverter and an inverter protection method, the inverter comprises a controller, a BOOST circuit, an inverter circuit and a temperature acquisition module, the input end of the BOOST circuit is used for being electrically connected with a photovoltaic string, the output end of the BOOST circuit is electrically connected with the input end of the inverter circuit, the output end of the inverter circuit is used for being electrically connected with a power grid, and the temperature acquisition module is electrically connected with the controller. The temperature acquisition module is used for acquiring the environment temperature of the inverter and transmitting the environment temperature to the controller. The controller is configured to adjust the input current range of the BOOST circuit according to the input voltage when the input voltage is within the preset voltage range, and control the output power of the BOOST circuit and the inverter circuit according to the environment temperature when the input voltage is not within the preset voltage range. According to the embodiment of the invention, the over-temperature protection of the inverter can be realized, the software derating control logic of the inverter can be simplified, and the reliability of the inverter is improved.

Description

Technical Field

[0001] The present application relates to the technical field of inverter equipment, and in particular to an inverter and an inverter protection method. Background Art

[0002] In order to maintain stable operation under harsh working conditions, inverters currently on the market usually install temperature sensors on the inverter substrate to detect the operating temperature of the inverter.

[0003] When the temperature sensor detects that the temperature of the BOOST circuit (i.e., the DC boost circuit) exceeds the set threshold of the internal controller, the controller in the inverter will reduce the output power of the inverter to ensure that the inverter can work at a reduced rating without damage under extreme conditions. In actual applications, when the BOOST circuit works at a low voltage, the controller reduces the output power of the inverter, but the temperature rise of the switch tube in the BOOST circuit will increase as the output power of the inverter decreases. Eventually, the controller will control the inverter to stop power output to avoid the temperature from affecting the working state of the inverter. When the inverter supports multiple string inputs, it is necessary to add a corresponding number of temperature sensors to monitor the temperature of the BOOST circuit to avoid the high temperature of any BOOST circuit affecting the working state of the inverter. However, the solution of adding temperature sensors to realize inverter over-temperature protection will increase the inverter's software derating control logic, which will reduce the reliability of the inverter. Summary of the invention

[0004] In view of the above, the present application provides an inverter and an inverter protection method, which are used to solve the problem that the software derating control logic of the inverter is complex and the product reliability is low.

[0005] The first aspect of the present application provides an inverter, including a controller, a BOOST circuit, an inverter circuit and a temperature acquisition module. The input end of the BOOST circuit is used to electrically connect to a photovoltaic string, the output end of the BOOST circuit is electrically connected to the input end of the inverter circuit, the output end of the inverter circuit is used to electrically connect to a power grid, and the temperature acquisition module is used to collect the ambient temperature of the inverter and transmit the ambient temperature to the controller. The controller is configured to: when the input voltage of the BOOST circuit is within a preset voltage range, adjust the input current range of the BOOST circuit according to the input voltage; when the input voltage is not within the preset voltage range, control the output power of the BOOST circuit and the inverter circuit according to the ambient temperature.

[0006] By adopting the embodiments of the present application, when the input voltage is within the preset voltage range, the controller adjusts the input current range of the BOOST circuit according to the input voltage to reduce the temperature rise of the switching device of the BOOST circuit, thereby preventing any BOOST circuit switching device from having an excessively high temperature rise and affecting the working state of the inverter. When the input voltage is not within the preset voltage range, the output power of the BOOST circuit and the inverter circuit is controlled according to the ambient temperature to reduce the temperature rise of the switching device of the BOOST circuit and the inverter circuit, thereby preventing the inverter circuit or any BOOST circuit switching device from having an excessively high temperature rise and affecting the working state of the inverter. Over-temperature protection of the inverter is implemented, the software derating control logic of the inverter is simplified, and the reliability of the inverter is improved.

[0007] As an optional implementation, the controller is also used to obtain a maximum input current range corresponding to the input voltage when the ambient temperature is the maximum operating ambient temperature, so as to control the BOOST circuit to work according to the maximum input current range.

[0008] As an optional implementation method, the controller is also used to adjust the input current range of the BOOST circuit and obtain the temperature rise of the switching device of the BOOST circuit, so that when the temperature rise of the switching device is within a preset temperature rise range, the input current range of the BOOST circuit is adjusted to the maximum input current range corresponding to the input voltage.

[0009] As an optional implementation method, the controller is also used to obtain the output power of the inverter and the maximum output power corresponding to the ambient temperature when the input voltage is not within a preset voltage range, so as to control the inverter to operate according to the maximum output power when the output power is greater than the maximum output power.

[0010] As an optional implementation, the temperature acquisition module includes at least two temperature acquisition units. The temperature acquisition unit is used to collect the sampled temperature in the inverter and transmit the sampled temperature to the controller; the controller is configured to determine the average of the sampled temperatures of at least two temperature acquisition units as the ambient temperature, and control the output power of the BOOST circuit and the inverter circuit according to the ambient temperature.

[0011] As an optional implementation method, the controller is also used to adjust the ambient temperature and set the output power of the inverter circuit and the BOOST circuit to the maximum output power corresponding to the ambient temperature, so as to set the maximum value of each sampling temperature as the sampling temperature corresponding to the maximum output power.

[0012] As an optional implementation, the inverter further includes a heat dissipation substrate. The BOOST circuit and the inverter circuit are arranged on the heat dissipation plate surface of the heat dissipation substrate, and the temperature acquisition module is arranged at the center of the heat dissipation substrate.

[0013] The second aspect of the present application also provides an inverter protection method, which is applied in an inverter. The inverter includes a controller, a BOOST circuit, an inverter circuit and a temperature acquisition module. The input end of the BOOST circuit is used to electrically connect to a photovoltaic string, the output end of the BOOST circuit is electrically connected to the input end of the inverter circuit, the output end of the inverter circuit is used to electrically connect to a power grid, and the temperature acquisition module is used to collect the ambient temperature of the inverter and transmit the ambient temperature to the controller. The inverter protection method includes: the controller obtains the ambient temperature of the inverter and the input voltage of the BOOST circuit; when the input voltage is within a preset voltage range, the controller adjusts the input current range of the BOOST circuit according to the input voltage; when the input voltage is not within the preset voltage range, the controller controls the output power of the BOOST circuit and the inverter circuit according to the ambient temperature.

[0014] By adopting the embodiments of the present application, after obtaining the ambient temperature and the input voltage, when the input voltage is within the preset voltage range, the input current range of the BOOST circuit is adjusted according to the input voltage to reduce the temperature rise of the switching device of the BOOST circuit, thereby preventing any BOOST circuit from having an excessively high temperature and affecting the working state of the inverter; and when the input voltage is not within the preset voltage range, the output power of the BOOST circuit and the inverter circuit is controlled according to the ambient temperature to reduce the temperature rise of the switching device of the BOOST circuit and the inverter circuit, thereby preventing the inverter circuit or any BOOST circuit from having an excessively high temperature and affecting the working state of the inverter, thereby realizing over-temperature protection of the inverter, simplifying the software derating control logic of the inverter, and improving the reliability of the inverter.

[0015] As an optional implementation method, the controller adjusts the input current range of the BOOST circuit according to the input voltage, including: the controller determines whether the ambient temperature is the maximum operating ambient temperature; if the ambient temperature is the maximum operating ambient temperature, the controller obtains the maximum input current range corresponding to the input voltage; the controller controls the BOOST circuit to work according to the maximum input current range.

[0016] As an optional implementation method, the controller obtains the maximum input current range corresponding to the input voltage, including: the controller adjusts the input current range of the BOOST circuit; the controller obtains the temperature rise of the switching device of the BOOST circuit; the controller determines whether the temperature rise of the switching device is within a preset temperature rise range; if the temperature rise of the switching device is within the preset temperature rise range, the controller adjusts the input current range of the BOOST circuit to the maximum input current range corresponding to the input voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of an inverter provided in one embodiment of the present application.

[0018] Figure 2It is a schematic diagram of the structure of an inverter provided in another embodiment of the present application.

[0019] Figure 3 This is a current waveform diagram of the switch tube Q1 in the BOOST circuit provided in one embodiment of the present application.

[0020] Figure 4 It is a maximum current line graph corresponding to the input voltage at the maximum operating ambient temperature of the inverter provided in one embodiment of the present application.

[0021] Figure 5 It is a schematic diagram of the structure of an inverter provided in another embodiment of the present application.

[0022] Figure 6 This is a flow chart of an inverter protection method provided in one embodiment of the present application.

[0023] Figure 7 This is a flow chart of an inverter protection method provided in another embodiment of the present application.

[0024] Figure 8 This is a flow chart of an inverter protection method provided in another embodiment of the present application. DETAILED DESCRIPTION

[0025] It should be noted that when an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be a centrally disposed element at the same time. When an element is considered to be "disposed on" another element, it may be directly disposed on the other element or there may be a centrally disposed element at the same time.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0027] The embodiments of the present application provide an inverter and an inverter protection method. In a specific scenario where the inverter supports multiple string inputs, the inverter protection method provided by the embodiments of the present application can be applied to control the temperature rise of the inverter. It can be understood that the inverter can be applied to the field of photovoltaic equipment to provide electric energy to users.

[0028] The inverter and inverter protection method in the embodiment of the present application can solve the problem of increasing material cost and installation complexity when implementing over-temperature protection for multiple string inverters, avoid the excessive temperature rise of the switch tube in any BOOST circuit affecting the working state of the inverter, and can also reduce the material cost and installation complexity of the inverter. The inverter and inverter protection method provided in the embodiment of the present application can realize over-temperature protection of the inverter and can reduce the installation complexity and material cost of multiple string inverters.

[0029] See also Figure 1 , Figure 1 FIG. 1 is a schematic diagram of an inverter provided in an embodiment of the present application. It can be understood that in the embodiment of the present application, the inverter can be applied in the field of photovoltaic power generation.

[0030] The inverter may include a controller 10, a BOOST circuit 20, an inverter circuit 30, and a temperature acquisition module 40. The input end of the BOOST circuit 20 is used to electrically connect to the photovoltaic string, the output end of the BOOST circuit 20 is electrically connected to the input end of the inverter circuit 30, the output end of the inverter circuit 30 is used to electrically connect to the power grid, and the temperature acquisition module 40 is used to collect the ambient temperature of the inverter and transmit the ambient temperature to the controller 10.

[0031] In practical applications, the BOOST circuit 20 is used to boost the voltage output by the photovoltaic string and output it to the inverter circuit 30, so that the boosted DC power is converted into AC power through the inverter circuit 30 and output to the grid.

[0032] The controller 10 is used to: when the input voltage of the BOOST circuit 20 is within the preset voltage range, adjust the input current range of the BOOST circuit 20 according to the input voltage; and when the input voltage is not within the preset voltage range, control the output power of the BOOST circuit 20 and the inverter circuit 30 according to the ambient temperature.

[0033] In practical applications, the controller 10 can control the output power of the inverter by controlling the switch tubes in the BOOST circuit 20 and the inverter circuit 30 to turn off, so as to control the temperature rise of the switch devices in the BOOST circuit 20 and the inverter circuit 30 in the inverter, and then control the ambient temperature of the inverter. The preset voltage range can be the input voltage of the inverter in the working state, and the input voltage is less than the full load voltage range of the inverter. The specific full load voltage is the maximum voltage value that the DC input terminal of the inverter can withstand when the inverter outputs the rated power. It is not specifically limited here, and it can be determined according to its actual application environment, and it is within the protection scope of this application.

[0034] See also Figure 2The BOOST circuit 20 includes an inductor L1, a diode D1 and a switch tube Q1, and the current waveform of the switch tube Q1 in the BOOST circuit 20 can be referred to. Figure 3 .

[0035] Specifically, the cathode of the diode D1 is electrically connected to the first input terminal of the inverter circuit 30, the anode of the diode D1 is electrically connected to the first terminal of the photovoltaic string through the inductor L1, the first terminal of the switch tube Q1 is electrically connected to the controller 10, the second terminal of the switch tube Q1 is electrically connected to the connection point between the anode of the diode D1 and the inductor L1, and the third terminal of the switch tube Q1 is electrically connected to the second terminal of the photovoltaic string and the second input terminal of the inverter circuit 30. Among them, the first terminal of the switch tube Q1 is the control terminal of the switch tube Q1, and the controller 10 can output a signal to the first terminal of the switch tube Q1 to control the switch tube Q1 to be turned off or turned on.

[0036] The diode D1 is used for freewheeling when the switch tube Q1 is turned off, and the inductor L1 is used for energy storage when the switch tube Q1 is turned on; the gain of the BOOST circuit 20 is Vo / Vin=1 / (1-D), where Vo is the output voltage of the BOOST circuit 20, Vin is the input voltage of the BOOST circuit 20, and D is the duty cycle; the turn-on time of the switch tube Q1 can be calculated by Ton=D×Ts, and the turn-off time of the switch tube Q1 can be calculated by Toff=(1-D)×Ts, where Ton is the turn-on time of the switch tube Q1, Tof f is the off time of the switch tube Q1, D is the duty cycle, Ts is the switching period of the switch tube Q1, and it can be seen from the gain of the BOOST circuit 20 that Vo / Vin=1 / (1-D) that when the output voltage Vo of the BOOST circuit 20 is constant, the smaller the input voltage Vin, the larger the duty cycle D will be, and the longer the on time Ton will be, so that the effective value of the current flowing through the switch tube Q1 will be larger. Therefore, it can be seen that in actual applications, the controller 10 can adjust the input current range of the BOOST circuit 20 by controlling the on time of the switch tube Q1. Specifically, when the input voltage is within the preset voltage range, the controller 10 can adjust the input current range of the BOOST circuit 20 by controlling the on time of the switch tube Q1 to reduce the temperature rise of the switch device of the BOOST circuit 20 and avoid excessive temperature rise of the switch device in the BOOST circuit 20 to damage the BOOST circuit 20. In practical applications, the switching devices in the BOOST circuit 20 and the inverter circuit 30 may be MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or IGBT (Insulated Gate Bipolar Transistor), which are not specifically limited here and may be determined according to the specific application environment, and are all within the protection scope of this application.

[0037] The inverter in this embodiment includes a controller 10, a BOOST circuit 20, an inverter circuit 30 and a temperature acquisition module 40, wherein the controller 10 adjusts the input current range of the BOOST circuit 20 according to the input voltage when the input voltage is within a preset voltage range, so as to reduce the temperature rise of the switch device of the BOOST circuit 20, and avoid the influence of the working state of the inverter due to the excessive temperature of any BOOST circuit 20, and when the input voltage is not within the preset voltage range, the output power of the BOOST circuit 20 and the inverter circuit 30 is controlled according to the ambient temperature, so as to reduce the temperature rise of the switch device of the BOOST circuit 20 and the inverter circuit 30, and avoid the influence of the working state of the inverter due to the excessive temperature rise of the switch device of the inverter circuit 20 or any BOOST circuit 30, thereby realizing the over-temperature protection of the inverter, simplifying the software derating control logic of the inverter, and improving the reliability of the inverter.

[0038] In an optional implementation, the controller 10 is further configured to obtain a maximum input current range corresponding to the input voltage when the ambient temperature is the maximum operating ambient temperature, so as to control the BOOST circuit 20 to operate according to the maximum input current range.

[0039] See also Figure 4 In actual applications, the controller 10 stores the maximum input current range curve of the inverter corresponding to each input voltage when the inverter is at the maximum operating ambient temperature. When the ambient temperature is the maximum operating ambient temperature, the controller 10 obtains the maximum input current range corresponding to the input voltage, and then controls the turn-on time of the switch tube Q1 in the BOOST circuit 20 according to the maximum input current range to control the input current range of the BOOST circuit 20.

[0040] Optionally, the controller 10 is further used to adjust the input current range of the BOOST circuit 20 and obtain the temperature rise of the switch device of the BOOST circuit 20, so that when the temperature rise of the switch device is within a preset temperature rise range, the input current range of the BOOST circuit 20 is adjusted to the maximum input current range corresponding to the input voltage. Figure 4 When the ambient temperature of the inverter is the maximum operating ambient temperature and the input voltage is equal to V1, the controller 10 adjusts the input current range of the BOOST circuit 20 to I1, and obtains the temperature rise T1 of the switching device of the BOOST circuit 20, and then determines whether the temperature rise T1 of the switching device is within the preset temperature rise range, that is, determines whether the temperature rise T1 of the switching device is the maximum operating temperature of the device. When the temperature rise T1 of the switching device is within the preset temperature rise range, the controller 10 adjusts the current input current range I1 of the BOOST circuit 20 to the maximum input current range corresponding to V1, so as to ensure that the inverter can output at the maximum power at the maximum operating ambient temperature.

[0041] The controller 10 can also adjust the maximum input current range I2 of the BOOST circuit 20 and obtain the temperature rise T2 of the switching device of the BOOST circuit 20 when the ambient temperature of the inverter is the maximum operating ambient temperature and the input voltage is equal to V2, and then judge whether the temperature rise T2 of the switching device is within the preset temperature rise range, that is, judge whether the temperature rise T2 of the switching device is the maximum operating temperature of the device. When the temperature rise T2 of the switching device is within the preset temperature rise range, the controller 10 adjusts the current input current range I2 of the BOOST circuit 20 to the maximum input current range corresponding to V2 to ensure that the inverter can output at maximum power at the maximum operating ambient temperature.

[0042] In practical applications, when the ambient temperature of the inverter is the maximum operating ambient temperature, the controller 10 can collect the maximum input current range corresponding to each input voltage in the range of V1-V3 to obtain the following: Figure 4 The voltage-current comparison curve shown enables the controller 10 to adjust the input current range of the BOOST circuit 20 according to the current value therein, thereby preventing the ambient temperature of the inverter from being too high due to excessive current and damaging the inverter.

[0043] This implementation method obtains the maximum input current range corresponding to the input voltage when the ambient temperature of the inverter is the maximum operating ambient temperature, so that the controller 10 can adjust the maximum input current range of the BOOST circuit 20 according to the current input voltage of the inverter, thereby preventing any BOOST circuit 20 from having an excessively high temperature and affecting the working state of the inverter. When the input voltage is not within the preset voltage range, the output power of the BOOST circuit 20 and the inverter circuit 30 is controlled according to the ambient temperature to reduce the temperature rise of the switching devices of the BOOST circuit 20 and the inverter circuit 30, thereby preventing the inverter circuit 20 or any BOOST circuit 30 from having an excessively high temperature and affecting the working state of the inverter. Over-temperature protection of the inverter is implemented, the software derating control logic of the inverter is simplified, and the reliability of the inverter is improved. In addition, by setting the input current range of the BOOST circuit 20 to the maximum input current range, the working efficiency of the inverter is guaranteed.

[0044] In an optional implementation, the controller 10 is also used to obtain the output power of the inverter and the maximum output power corresponding to the ambient temperature when the input voltage of the BOOST circuit 20 is not within a preset voltage range, so as to control the inverter to operate according to the maximum output power when the output power of the inverter is greater than the maximum output power.

[0045] This implementation method implements over-temperature protection of the inverter by controlling the output of the inverter according to the maximum output power corresponding to the current ambient temperature of the inverter when the input voltage of the inverter is not within the preset voltage range, and controls the inverter to operate according to the maximum output power when the output power of the inverter is greater than the maximum output power, so as to ensure the output power of the inverter while implementing overheat protection of the inverter, thereby improving the safety and reliability of the inverter.

[0046] In an alternative implementation, see Figure 5 The temperature acquisition module 40 may include at least two temperature acquisition units (41, 42...4N as shown in the figure).

[0047] The temperature acquisition unit is used to acquire the sampled temperature in the inverter and transmit the sampled temperature to the controller 10. The controller 10 is configured to calculate the average of the sampled temperatures and determine the average as the ambient temperature to control the output power of the BOOST circuit 20 and the inverter circuit 30 according to the ambient temperature.

[0048] like Figure 5 As shown, each temperature acquisition unit outputs the collected sampled temperature to the controller 10, and the controller 10 adds up the sampled temperatures to obtain the corresponding sum value, and divides the sum value by the number of temperature sampling units to obtain the average value of each sampled temperature, so as to determine that the average value is the ambient temperature of the inverter, so that the controller 10 can control the output power of the BOOST circuit 20 and the inverter circuit 30 according to the ambient temperature.

[0049] Optionally, the controller 10 can adjust the ambient temperature of the inverter, and after setting the output power of the inverter to the maximum output power corresponding to the ambient temperature, obtain the sampled temperatures collected by each temperature sampling unit, and set the maximum value of the sampled temperatures as the sampled temperature corresponding to the maximum output power of the inverter, so that when the collected temperature of any temperature sampling unit is the temperature value, the control can timely control the output power of the inverter, thereby reducing the risk of overheating protection of the inverter. For example, the controller 10 can set the ambient temperature of the inverter to T1, and set the output power of the inverter to the maximum output power P1 corresponding to the ambient temperature T1, obtain the sampled temperatures Ta1, Tb1, Tc1, ... Tn1 collected by each temperature sampling unit, and set the maximum value of the sampled temperatures as the ambient temperature corresponding to the maximum output power of the inverter, so that when the collected temperature of any temperature sampling unit is the temperature value, the control can timely control the switch tubes in the BOOST circuit 20 and the inverter circuit 30, thereby controlling the output power of the inverter, so as to avoid the output power of the inverter being too high and affecting the working state of the inverter, thereby realizing over-temperature protection of the inverter.

[0050] In practical applications, when the inverter supports multiple string inputs, the inverter can also be Figure 5 As shown, a corresponding number of BOOST circuits 20 are included (only N BOOST circuits 20 are shown as an example in the figure), which is not limited to this in actual applications and depends on the specific application environment, all of which are within the protection scope of this application.

[0051] This implementation method realizes over-temperature protection of multiple string inverters by setting multiple temperature acquisition units to collect the ambient temperature of the inverter. At the same time, it simplifies the software derating control logic of the inverter, improves the reliability of the inverter, and further improves the ambient temperature acquisition accuracy and over-temperature protection reliability of the inverter.

[0052] See also Figure 6 In an optional implementation, the inverter further includes a heat dissipation substrate 60 .

[0053] The BOOST circuit 20 and the inverter circuit 30 are arranged on the heat dissipation plate surface of the heat dissipation substrate 60 , and the temperature acquisition module 40 is arranged at the center position of the heat dissipation substrate 60 .

[0054] This implementation method arranges the BOOST circuit 20 and the inverter circuit 30 on the heat dissipation plate surface of the heat dissipation substrate 60 so that the BOOST circuit 20 and the inverter circuit 30 can dissipate heat through the heat dissipation substrate 60 when they are working, thereby improving the safety and reliability of the inverter, and the ambient temperature collection accuracy of the inverter is improved by arranging the temperature acquisition module 40 at the center position of the heat dissipation substrate 60.

[0055] See also Figure 7 , Figure 7 The figure is a flowchart of the steps of an inverter protection method provided by another embodiment of the present application. The inverter protection method can be applied to the inverter as described in any of the above embodiments, and the method may include the following steps: Step S71: The controller obtains the ambient temperature of the inverter and the input voltage of the BOOST circuit.

[0056] by Figure 1 Taking the inverter shown as an example, the controller 10 can obtain the input voltage of the BOOST circuit 20 and detect the ambient temperature of the inverter in real time through the temperature acquisition module 40.

[0057] When the input voltage is within the preset voltage range, the controller 10 executes step S62 , and when the input voltage is not within the preset voltage range, the controller 10 executes step S63 .

[0058] Step S72: The controller adjusts the input current range of the BOOST circuit according to the input voltage.

[0059] When the input voltage is within the preset voltage range, the controller 10 adjusts the input current range of the BOOST circuit 20 according to the input voltage to prevent the input current range of the BOOST circuit 20 from being too large, causing the ambient temperature of the inverter to be too high, and causing the inverter to malfunction.

[0060] For details, please refer to Figure 2 When the input voltage is within the preset voltage range, the controller 10 controls the on-time of the switch tube Q1 according to the input voltage to change the input current range of the BOOST circuit 20, reduce the temperature rise of the switch device of the BOOST circuit 20, and thus realize the over-temperature protection of the inverter.

[0061] Step S73: The controller controls the output power of the BOOST circuit and the inverter circuit according to the ambient temperature.

[0062] When the input voltage is not within the preset voltage range, the controller 10 controls the output power of the BOOST circuit and the inverter circuit according to the input voltage to prevent the output power of the inverter from being too large and the ambient temperature of the inverter from being too high.

[0063] For details, please refer to Figure 1 When the input voltage is not within the preset voltage range, the controller 10 controls the inverter circuit 30 and the BOOST circuit 20 according to the ambient temperature to reduce the temperature rise of the switching devices of the inverter, thereby realizing over-temperature protection of the inverter.

[0064] After obtaining the ambient temperature and the input voltage, the implementation method adjusts the input current range of the BOOST circuit 20 according to the input voltage when the input voltage is within the preset voltage range, so as to reduce the temperature rise of the switch device of the BOOST circuit 20, and avoid the influence of the working state of the inverter due to the excessive temperature of any BOOST circuit 20; and when the input voltage is not within the preset voltage range, the output power of the BOOST circuit 20 and the inverter circuit 30 is controlled according to the ambient temperature, so as to reduce the temperature rise of the switch device of the BOOST circuit 20 and the inverter circuit 30, and avoid the influence of the working state of the inverter due to the excessive temperature rise of the switch device of the inverter circuit 20 or any BOOST circuit 30, thereby realizing the over-temperature protection of the inverter, simplifying the software derating control logic of the inverter, and improving the reliability of the inverter.

[0065] In an alternative implementation, see Figure 8 , wherein step S72 comprises: Step S81: The controller determines whether the ambient temperature is the maximum operating ambient temperature.

[0066] The control determines whether the ambient temperature of the inverter is the maximum operating ambient temperature. If the ambient temperature of the inverter is the maximum operating ambient temperature, step S82 is executed. If the ambient temperature of the inverter is not the maximum operating ambient temperature, the control returns to step S81.

[0067] Step S82: the controller obtains the maximum input current range corresponding to the input voltage.

[0068] If the ambient temperature is the maximum operating ambient temperature, obtain the maximum input current range corresponding to the input voltage. Figure 5 In actual applications, the controller 10 stores the maximum input current range curve of the inverter corresponding to each input voltage when the inverter is at the maximum operating ambient temperature.

[0069] See also Figure 4 When the ambient temperature of the inverter is the maximum operating ambient temperature and the input voltage is equal to V1, the controller 10 adjusts the input current range of the BOOST circuit 20 to I1, and obtains the temperature rise T1 of the switching device of the BOOST circuit 20, and then determines whether the temperature rise T1 of the switching device is within the preset temperature rise range, that is, determines whether the temperature rise T1 of the switching device is the maximum operating temperature of the device. When the temperature rise T1 of the switching device is within the preset temperature rise range, the controller 10 adjusts the current input current range I1 of the BOOST circuit 20 to the maximum input current range corresponding to V1, so as to ensure that the inverter can output at the maximum power at the maximum operating ambient temperature.

[0070] The controller 10 can also adjust the maximum input current range I2 of the BOOST circuit 20 and obtain the temperature rise T2 of the switching device of the BOOST circuit 20 when the ambient temperature of the inverter is the maximum operating ambient temperature and the input voltage is equal to V2, and then judge whether the temperature rise T2 of the switching device is within the preset temperature rise range, that is, judge whether the temperature rise T2 of the switching device is the maximum operating temperature of the device. When the temperature rise T2 of the switching device is within the preset temperature rise range, the controller 10 adjusts the current input current range I2 of the BOOST circuit 20 to the maximum input current range corresponding to V2 to ensure that the inverter can output at maximum power at the maximum operating ambient temperature.

[0071] In practical applications, when the ambient temperature of the inverter is the maximum operating ambient temperature, the controller 10 can collect the maximum input current range corresponding to each input voltage in the range of V1-V3 to obtain the following: Figure 4 The voltage-current comparison curve shown enables the controller 10 to control the input current range of the BOOST current according to the current value therein, thereby preventing the ambient temperature of the inverter from being too high due to excessive current and damaging the inverter.

[0072] Step S83: the controller controls the BOOST circuit to operate according to the maximum input current range.

[0073] After obtaining the maximum input current range corresponding to the input voltage, the controller 10 controls the turn-on time of the switch tube Q1 in the BOOST circuit 20 according to the maximum input current range, so as to control the input current range of the BOOST circuit 20 .

[0074] This implementation method obtains the maximum input current range corresponding to the input voltage when the ambient temperature of the inverter is the maximum operating ambient temperature, so that the controller 10 can adjust the maximum input current range of the BOOST circuit 20 according to the current input voltage of the inverter, so as to reduce the temperature rise of the switching device of the BOOST circuit 20, avoid the excessive temperature of any BOOST circuit 20 affecting the working state of the inverter, and by setting the input current range of the BOOST circuit 20 to the maximum input current range, the working efficiency of the BOOST circuit 20 is guaranteed.

[0075] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or basic features of the present application. Therefore, as long as they are within the scope of the essence and spirit of the present application, appropriate changes and modifications made to the above embodiments should fall within the scope of protection claimed in the present application.

Claims

1. An inverter, characterized in that: include: Controller, switch DC boost BOOST circuit, inverter circuit and temperature acquisition module; The input end of the BOOST circuit is used to electrically connect to the photovoltaic string, the output end of the BOOST circuit is electrically connected to the input end of the inverter circuit, the output end of the inverter circuit is used to electrically connect to the power grid, and the temperature acquisition module is used to collect the ambient temperature of the inverter and transmit the ambient temperature to the controller; The controller is configured to: When the input voltage of the BOOST circuit is within a preset voltage range, adjusting the input current range of the BOOST circuit according to the input voltage; When the input voltage is not within a preset voltage range, the output power of the BOOST circuit and the inverter circuit is controlled according to the ambient temperature.

2. The inverter according to claim 1, characterized in that: The controller is further used to obtain a maximum input current range corresponding to the input voltage when the ambient temperature is the maximum operating ambient temperature, so as to control the BOOST circuit to operate according to the maximum input current range.

3. The inverter according to claim 2, characterized in that: The controller is further used to adjust the input current range of the BOOST circuit and obtain the temperature rise of the switch device of the BOOST circuit, so as to adjust the input current range of the BOOST circuit to the maximum input current range corresponding to the input voltage when the temperature rise of the switch device is within a preset temperature rise range.

4. The inverter according to claim 1, characterized in that: The controller is also used to obtain the output power of the inverter and the maximum output power corresponding to the ambient temperature when the input voltage is not within the preset voltage range, so as to control the inverter to operate according to the maximum output power when the output power is greater than the maximum output power.

5. The inverter according to claim 1, characterized in that: The temperature acquisition module includes: at least two temperature acquisition units; The temperature acquisition unit is used to acquire a sampled temperature in the inverter and transmit the sampled temperature to the controller; The controller is configured to determine an average value of the sampled temperatures of the at least two temperature acquisition units as the ambient temperature, and control the output power of the BOOST circuit and the inverter circuit according to the ambient temperature.

6. The inverter according to claim 5, characterized in that: The controller is also used to adjust the ambient temperature, and set the output power of the inverter circuit and the BOOST circuit to the corresponding maximum output power under the ambient temperature, so as to set the maximum value of each of the sampled temperatures as the sampled temperature corresponding to the maximum output power.

7. The inverter according to claim 1, characterized in that: The inverter further includes: a heat dissipation substrate; The BOOST circuit and the inverter circuit are arranged on the heat dissipation plate surface of the heat dissipation substrate, and the temperature acquisition module is arranged at the center position of the heat dissipation substrate.

8. An inverter protection method, characterized in that: Applied in an inverter, the inverter includes a controller, a BOOST circuit, an inverter circuit and a temperature acquisition module, the input end of the BOOST circuit is used to electrically connect to a photovoltaic string, the output end of the BOOST circuit is electrically connected to the input end of the inverter circuit, the output end of the inverter circuit is used to electrically connect to a power grid, the temperature acquisition module is used to collect the ambient temperature of the inverter and transmit the ambient temperature to the controller, and the inverter protection method includes: The controller obtains the ambient temperature of the inverter and the input voltage of the BOOST circuit; When the input voltage is within a preset voltage range, the controller adjusts the input current range of the BOOST circuit according to the input voltage; When the input voltage is not within the preset voltage range, the controller controls the output power of the BOOST circuit and the inverter circuit according to the ambient temperature.

9. The inverter protection method according to claim 8, characterized in that: The controller adjusts the input current range of the BOOST circuit according to the input voltage, including: The controller determines whether the ambient temperature is the maximum operating ambient temperature; If the ambient temperature is the maximum operating ambient temperature, the controller obtains the maximum input current range corresponding to the input voltage; The controller controls the BOOST circuit to operate according to the maximum input current range.

10. The inverter protection method according to claim 9, characterized in that: The controller obtains a maximum input current range corresponding to the input voltage, including: The controller adjusts the input current range of the BOOST circuit; The controller obtains the temperature rise of the switch device of the BOOST circuit; The controller determines whether the temperature rise of the switch device is within a preset temperature rise range; If the temperature rise of the switch device is within a preset temperature rise range, the controller adjusts the input current range of the BOOST circuit to be a maximum input current range corresponding to the input voltage.

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