Photovoltaic power generation inverter and power control method

Abstract

This application provides a photovoltaic inverter and a power control method. The photovoltaic inverter includes an inverter circuit, a plurality of voltage conversion circuits, a plurality of acquisition circuits, and a control circuit. . system The circuit is ,Ta When the input current of the target voltage conversion circuit is equal to or greater than a current threshold of the target voltage conversion circuit, a switch in the target voltage conversion circuit is turned on or off to reduce the current or input power of the target voltage conversion circuit. control According to this application, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the input power of the voltage conversion circuit is reduced to ensure the safety of the power supply, and the stability and power supply efficiency of the photovoltaic power generation inverter can be improved. 。

Description

[Technical field]

[0001] child The application relates to the field of power electronics technology, and in particular to a photovoltaic power generation inverter and a power control method. [Background technology]

[0002] In the field of power electronics technology, an inverter circuit in a photovoltaic inverter is usually used to convert DC energy to AC energy so that electrical energy can be transmitted between a power source and a load. For example, in the field of photovoltaic power sources, a photovoltaic inverter can convert DC energy output by a DC power source (e.g., a photovoltaic (PV) panel) into AC energy and provide the AC energy for a load or a power grid to use. Generally, a control circuit (e.g., a Maximum Power Point Tracking (MPPT) control circuit) in a photovoltaic inverter controls the output current of a PV panel (i.e., the input current of the photovoltaic inverter) based on the output voltage of the PV panel (i.e., the input voltage of the photovoltaic inverter), so that the PV panel outputs electrical energy to the load with maximum power. In the course of research and practice, the inventors of this application have found that in the prior art, a photovoltaic inverter usually converts the DC voltage provided by each group of PV panels into a DC bus voltage (e.g., converts the voltage of each group of PV panels into a DC bus voltage) by using multiple voltage conversion circuits. S The voltage converter uses a DC to DC converter to convert the DC energy to AC energy, and then uses an inverter circuit to convert the DC energy to AC energy to meet the voltage requirements of different loads. There are differences between groups of PV panels (e.g., different lengths or different light intensities). Therefore, the output voltage of the PV panels connected to the voltage converter circuit (i.e., the input voltage of the voltage converter circuit) and the SWhen the difference between the input voltage and the output voltage is too large, the input current in the voltage conversion circuit is usually high, which may result in failure or damage to elements in the voltage conversion circuit (e.g., switches in the voltage conversion circuit) due to overvoltage, overcurrent, or overheating. Summary of the Invention

[0003] This application provides a photovoltaic inverter and a power control method. When the input current of a target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the duty cycle of the switch can be adjusted through a control circuit to reduce the input power of the voltage conversion circuit, thereby improving the stability and power supply efficiency of the photovoltaic inverter while ensuring the safety of the power supply. The structure is simple, and the method is straightforward and highly applicable.

[0004] According to a first aspect, the present application provides a photovoltaic inverter. The photovoltaic inverter may include an inverter circuit, a plurality of voltage conversion circuits, a plurality of acquisition circuits, and a control circuit. One voltage conversion circuit may include at least one switch. Here, one end of each voltage conversion circuit may be configured to be connected to each of a plurality of groups of photovoltaic panels. The other end of each voltage conversion circuit may be configured to be connected to a buffer. S The plurality of acquisition circuits may be connected in parallel and then connected to a load via an inverter circuit. S A control circuit is connected to the switch in each voltage conversion circuit. Here, the plurality of acquisition circuits may be configured to detect the input voltage and the balance of the target voltage conversion circuit. S The target voltage conversion circuit may be any one or more of the plurality of voltage conversion circuits. Here, the control circuit may be configured to detect a voltage between the input voltage of the target voltage conversion circuit and the balance. SThe control circuit may adjust a current threshold of the target voltage conversion circuit based on the input current of the target voltage conversion circuit and the input power of the target voltage conversion circuit, where the control circuit may further adjust a duty cycle of a switch in the target voltage conversion circuit to turn on or off a switch in the target voltage conversion circuit to reduce a current or input power of the target voltage conversion circuit when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit. control The device may be configured to:

[0005] In this application, a photovoltaic panel may be connected to a load as a DC power source via a photovoltaic inverter. The photovoltaic inverter may convert DC energy provided by the photovoltaic panel into AC energy and provide the AC energy to the load. Here, the photovoltaic inverter may include an inverter circuit and a plurality of voltage conversion circuits. The DC power source may include a plurality of groups of photovoltaic panels (each group of photovoltaic panels may include one photovoltaic panel or multiple photovoltaic panels). Each group of photovoltaic panels may be connected to the inverter circuit via one voltage conversion circuit. The voltage conversion circuit may convert the DC voltage provided by the photovoltaic panel into AC energy and provide the AC energy to the load. Here, the photovoltaic inverter may include an inverter circuit and a plurality of voltage conversion circuits. The DC power source may include a plurality of groups of photovoltaic panels (each group of photovoltaic panels may include one photovoltaic panel or multiple photovoltaic panels). Each group of photovoltaic panels may be connected to the inverter circuit via one voltage conversion circuit. S The photovoltaic inverter may convert the DC energy into AC energy through an inverter circuit, so that the AC voltage output by the photovoltaic inverter can be adapted to loads in multiple voltage ranges. In an application scenario involving multiple groups of photovoltaic panels, there are differences between the groups of photovoltaic panels (e.g., different lengths, different shapes, or different light intensities). Therefore, the output voltage of the photovoltaic panels connected to the voltage conversion circuit (i.e., the input voltage of the voltage conversion circuit) and the balance SWhen the difference between the input voltage and the output voltage is too large, the input current in the voltage conversion circuit is usually high. As a result, overvoltage (too large voltage difference), overcurrent (too high current), or overheating (too high temperature) may cause failure or damage to elements in the voltage conversion circuit (e.g., switches in the voltage conversion circuit). Here, the photovoltaic inverter may further include a control circuit and an acquisition circuit. The acquisition circuit may acquire power supply parameters of the photovoltaic inverter (e.g., input voltage and / or output voltage of the voltage conversion circuit, input current and / or output current of the voltage conversion circuit, temperature of the voltage conversion circuit, balance, etc.). S The control circuit may detect the input and output voltages of the inverter circuit, the input and output currents of the inverter circuit, and the temperature of the inverter circuit. Here, the control circuit may determine the operating state of the photovoltaic inverter based on the power supply parameters of the photovoltaic inverter. Here, an example is used in which one (or more) voltage conversion circuits that need to be controlled by the control circuit are the target voltage conversion circuits. The control circuit may detect the input and output voltages of the target voltage conversion circuit. S After the current threshold of the target voltage conversion circuit is obtained, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the control circuit adjusts the duty cycle of the switch in the target voltage conversion circuit (e.g., reduces the duty cycle of the switch in the target voltage conversion circuit) to turn on or off the switch in the target voltage conversion circuit so as to reduce the current or input power of the target voltage conversion circuit, in order to protect the operational safety of the voltage conversion circuit. control possible.

[0006] According to this application, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the photovoltaic inverter can adjust the duty cycle of the switch through the control circuit to reduce the input power of the voltage conversion circuit, thereby improving the stability and power supply efficiency of the photovoltaic inverter while ensuring the safety of the power supply. The structure is simple, and the method is straightforward and has high applicability.

[0007] Referring to the first aspect, in a first possible implementation, the acquisition circuit may be further configured to detect a temperature of the target voltage conversion circuit. The control circuit may further detect the input voltage and balance of the target voltage conversion circuit when the temperature of the target voltage conversion circuit is equal to or greater than a temperature threshold. S and the first current threshold. It can be understood that the control circuit can determine the operation state of the target voltage conversion circuit in a number of ways, and can further determine whether the input power (or input current) of the target voltage conversion circuit needs to be controlled. In other words, the control circuit can determine the operation state of the target voltage conversion circuit in a number of ways, and can further determine whether the duty cycle of the switch in the target voltage conversion circuit needs to be adjusted. For example, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the target voltage conversion circuit can be considered to be in an operation state in which the input power needs to be reduced (or, in other words, the switch in the target voltage conversion circuit is operating in a harsh environment and will be damaged at a high risk if it continues to operate). In this case, the control circuit needs to reduce the input current and / or the input power of the target voltage conversion circuit. Here, when the operating temperature of the switch in the target voltage conversion circuit is different, the input current that the switch can withstand may be different even if the voltage difference borne by the switch is the same. For example, when the operating temperature of the switch in the target voltage conversion circuit is high (for example, the temperature of the target voltage conversion circuit is equal to or higher than a temperature threshold), the control circuit SThe maximum input current (e.g., a first current threshold) that the switch in the target voltage conversion circuit can withstand may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., based on the corresponding nominal current when various models of switches bear different voltage differences), or based on a current threshold acquired by the photovoltaic power inverter in a manner such as acquisition, collection, reception, detection, or storage. For example, the photovoltaic power inverter or an external central control system may calculate a curve of a corresponding current threshold when the switch bears different voltage differences at a specific operating temperature or a specific operating temperature range (e.g., a first operating temperature range equal to or greater than the temperature threshold) in the operation process (or design process) of the voltage conversion circuit. Also, the control circuit may obtain the first current threshold based on the curve. The first current threshold may be specifically set based on an application scenario. It may be understood that the first current threshold here may be one current, multiple discrete currents, or a current range including multiple discrete currents or continuous currents.

[0008] In this application, when the operating temperature of the switch in the target voltage conversion circuit is high (e.g., the temperature of the target voltage conversion circuit is equal to or higher than a temperature threshold), if the input current of the switch in the target voltage conversion circuit is equal to or higher than a first current threshold, it indicates that the target voltage conversion circuit is in an operating state in which the target voltage conversion circuit needs to be adjusted, and the control circuit may reduce the duty cycle of the switch in the target voltage conversion circuit to further reduce the input power of the target voltage conversion circuit, thereby avoiding the elements in the target voltage conversion circuit from being damaged by overheating and improving the safety of the target voltage conversion circuit. Also, the control circuit does not completely cut off the input electric energy of the target voltage conversion circuit. This ensures the efficiency of electric energy transmission on the basis of ensuring safety.

[0009] Referring to the first possible implementation of the first aspect, in a second possible implementation, the control circuit further comprises: a control circuit for controlling a balance between the input voltage of the target voltage conversion circuit and the input voltage of the target voltage conversion circuit when the temperature of the target voltage conversion circuit is less than a temperature threshold. S and the second current threshold is greater than or equal to the first current threshold. It can be understood that the control circuit can determine the operating state of the target voltage conversion circuit in a number of ways, and can further determine whether the input power (or input current) of the target voltage conversion circuit needs to be controlled. In other words, the control circuit can determine the operating state of the target voltage conversion circuit in a number of ways, and can further determine whether the duty cycle of the switch in the target voltage conversion circuit needs to be adjusted. For example, when the input current of the target voltage conversion circuit is greater than or equal to the current threshold of the target voltage conversion circuit, the target voltage conversion circuit can be considered to be in an operating state in which the input power needs to be reduced (or, in other words, the switch in the target voltage conversion circuit is operating in a harsh environment and will be damaged at a high risk if it continues to operate). In this case, the control circuit needs to reduce the input current and / or the input power of the target voltage conversion circuit. Here, when the operating temperature of the switch in the target voltage conversion circuit is different, the input current that the switch can withstand may be different even if the voltage difference borne by the switch is the same. For example, when the operating temperature of the switch in the target voltage conversion circuit is low (for example, the temperature of the target voltage conversion circuit is below a temperature threshold), the control circuit may reduce the voltage difference borne by the switch in the target voltage conversion circuit (for example, the input voltage and the balance SThe second current threshold may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., the difference between the first and second voltage thresholds). Here, the second current threshold is smaller than the first voltage threshold. The value of the second current threshold may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., the corresponding nominal current when various models of switches bear different voltage differences), or may be determined based on the current threshold obtained by the photovoltaic power inverter in a manner such as acquisition, collection, reception, detection, or storage. For example, the photovoltaic power inverter or an external central control system may calculate a corresponding current threshold curve when the switch bears different voltage differences at a specific operating temperature or a specific operating temperature range (e.g., a second operating temperature range lower than the temperature threshold) in the operation process (or design process) of the voltage conversion circuit. Also, the control circuit may obtain the second current threshold based on the curve. The second current threshold may be specifically set based on the application scenario. It can be appreciated that the second current threshold herein can be a single current, a number of discrete currents, or a range of currents including a number of discrete currents or a continuous current.

[0010] In this application, when the operating temperature of the switch in the target voltage conversion circuit is low (e.g., the temperature of the target voltage conversion circuit is below the temperature threshold), if the input current of the switch in the target voltage conversion circuit is equal to or greater than the second current threshold, it indicates that the target voltage conversion circuit is in an operating state in which the target voltage conversion circuit needs to be adjusted, and the control circuit may reduce the duty cycle of the switch in the target voltage conversion circuit to further reduce the input power of the target voltage conversion circuit, thereby avoiding the elements in the target voltage conversion circuit from being damaged by overheating and improving the safety of the target voltage conversion circuit. Also, the control circuit does not completely cut off the input electric energy of the target voltage conversion circuit. This ensures the efficiency of electric energy transmission on the basis of ensuring safety.

[0011] Referring to the first aspect or any of the possible implementations of the first aspect, in a third possible implementation, the control circuit further generates a switching modulation signal based on the input current of the target voltage conversion circuit and the current threshold of the target voltage conversion circuit when the input current of the target voltage conversion circuit is equal to or greater than a current threshold of the target voltage conversion circuit, and controls the duty cycle of the switch in the target voltage conversion circuit based on the switching modulation signal. adjustment and turn on or off the switch in the target voltage conversion circuit. control Here, a control circuit (e.g., a current regulation loop (e.g., a proportional regulation circuit or a proportional-integral regulation circuit) and a drive control circuit, or other circuit having a current regulation function and a drive control function) generates a switching modulation signal based on an input current of the target voltage conversion circuit and a current threshold of the target voltage conversion circuit to regulate the duty cycle of a switch in the target voltage conversion circuit. adjustment For example, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the control circuit generates a reference value that is smaller than the current threshold based on the current threshold of the target voltage conversion circuit, and adjusts the duty cycle of the switch in the target voltage conversion circuit based on the switching modulation signal by using the input current of the target voltage conversion circuit as a variable that needs to be adjusted. adjustment The control circuit may generate a switching modulation signal for adjusting the input current in the target voltage conversion circuit to be less than the current threshold (i.e., the above-mentioned reference value) of the target voltage conversion circuit. Here, the control circuit may generate a signal such as a pulse width modulation (PWM) wave as the switching modulation signal, or may generate a driving pulse signal as the switching modulation signal based on the PWM wave. Here, the switching modulation signal may be a signal that adjusts the duty cycle of a switch in the target voltage conversion circuit to be less than the current threshold (i.e., the above-mentioned reference value) of the target voltage conversion circuit. adjustmentand may further control the input current and / or input power of the target voltage conversion circuit. For example, the control circuit may reduce the duty cycle of a switch in the target voltage conversion circuit to reduce the input current of the target voltage conversion circuit and reduce the input power of the target voltage conversion circuit. It can be understood that the control circuit provided in this application may use a discontinuous pulse width modulation (DPWM) wave as the switching modulation signal, or may use another PWM wave (e.g., a sinusoidal pulse width modulation (SPWM) wave, a third harmonic injection pulse width modulation (THIPWM) wave, or a carrier based space vector pulse width modulation (CBPWM) wave) as the switching modulation signal, and may use a driving pulse signal generated based on these PWM waves as the switching modulation signal. The application range is wide and the control effect is good.

[0012] Referring to the first aspect or any possible implementation of the first aspect, in a fourth possible implementation, the control circuit further adjusts a duty cycle of a switch in the target voltage conversion circuit to turn on or off the switch in the target voltage conversion circuit so that the input power of the target voltage conversion circuit remains at a maximum target input power when the input current of the target voltage conversion circuit is less than a current threshold of the target voltage conversion circuit. control The device may be configured to:

[0013] Here, when the input current of the target voltage conversion circuit is less than a current threshold (e.g., a third current threshold) of the target voltage conversion circuit, the target voltage conversion circuit may be considered to be in an operating state in which the input power does not need to be reduced (in other words, the switch in the target voltage conversion circuit is operating in a safe environment with a low risk of damage). In this case, the control circuit may adjust the duty cycle of the switch in the target voltage conversion circuit so that the input power of the target voltage conversion circuit remains at the maximum target input power (e.g., the photovoltaic panel connected to the target voltage conversion circuit operates at the maximum power point). Here, the value of the third current threshold may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., based on the corresponding nominal current when various models of switches bear different voltage differences), or may be determined based on a current threshold obtained by the photovoltaic inverter in a manner such as acquisition, collection, reception, detection, or storage. For example, the photovoltaic power inverter or an external central control system may calculate a corresponding current threshold curve when the switch bears different voltage differences at a specific operating temperature or a specific operating temperature range (e.g., a first operating temperature range equal to or greater than a temperature threshold, or a second operating temperature range equal to or less than a temperature threshold) during the operation (or design) of the voltage conversion circuit. The control circuit may obtain a third current threshold based on the curve. The third current threshold may be specifically set based on an application scenario. It may be understood that the third current threshold here may be one current, multiple discrete currents, or a current range including multiple discrete currents or continuous currents. For example, in a first operating temperature range equal to or greater than a temperature threshold, the third current threshold may be equal to or less than the first current threshold. In another example, in a second operating temperature range equal to or less than a temperature threshold, the third current threshold may be equal to or less than the second current threshold. When the third voltage threshold is smaller than the first current threshold (or the second current threshold), the solar power inverter can avoid repeatedly decreasing or increasing the input power of the target voltage conversion circuit via the control circuit when the input current of the target voltage conversion circuit is not stably smaller than the first current threshold (or the second current threshold).In other words, when the third voltage threshold is less than the first current threshold (or the second current threshold), after the input current of the target voltage conversion circuit is stable (e.g., stable and less than the third current threshold), the target voltage conversion circuit of the solar power inverter may be in an operating state where the input power does not need to be reduced (or, in other words, the switches in the target voltage conversion circuit are operating in a safe environment with low risk of damage). In this case, the control circuit may adjust the duty cycle of the switches in the target voltage conversion circuit so that the input power of the target voltage conversion circuit remains at the maximum target input power (e.g., the solar panel connected to the target voltage conversion circuit operates at the maximum power point). This improves power supply efficiency.

[0014] Referring to the first embodiment or any of the possible implementations of the first embodiment, in a fifth possible implementation, the inverter circuit may include a switch. S Adjusting the duty cycle of a switch in the inverter circuit to turn on or off a switch in the inverter circuit so as to reduce the output power of the inverter circuit when the voltage is equal to or greater than the bus voltage threshold. control It can be appreciated that the control circuit can determine the operating state of the photovoltaic inverter in a number of ways, and can further determine whether the output power (or output current) of the photovoltaic inverter (e.g., inverter circuit) needs to be controlled. S When the voltage is equal to or greater than the bus voltage threshold, the inverter circuit may be considered to be in an operating condition that requires a reduced output power (or, in other words, the elements in the photovoltaic inverter are operating in a harsh environment and are at high risk of being damaged if they continue to operate). In this case, the control circuitry needs to reduce the output current and / or output power of the inverter circuit. It may be understood that the bus voltage threshold here may be a voltage, a number of discrete voltages, or a voltage range that includes a number of discrete or continuous voltages.

[0015] In this application, S High voltage (e.g. S When the voltage is equal to or greater than the bus voltage threshold, it indicates that the photovoltaic inverter is in an operating state where the output power needs to be reduced. The control circuit can reduce the duty cycle of each switch in the inverter circuit to further reduce the output power of the inverter circuit, to prevent the elements in the photovoltaic inverter from being damaged by overheating, and further improve the safety of the power supply.

[0016] According to a second aspect, the present application provides a power control method. The control method is applicable to a solar power generation system. The solar power generation system may include an inverter circuit, a plurality of voltage conversion circuits, an acquisition circuit, and a control circuit. One voltage conversion circuit may include at least one switch. Here, one end of each voltage conversion circuit may be configured to be connected to each of a plurality of groups of solar power generation panels. The other end of each voltage conversion circuit may be configured to be connected to a buffer. S The voltage conversion circuits, the inverter circuit, and the load are connected in parallel to each other. vinegar, and a control circuit connected to the switches in each voltage conversion circuit. The control circuit is connected to a switch in each voltage conversion circuit. The method includes: The input voltage of the target voltage conversion circuit, the input current of the target voltage conversion circuit, and S The target voltage conversion circuit is any one or more of the multiple voltage conversion circuits, and the input voltage of the target voltage conversion circuit and the balance S and adjusting a current threshold of the target voltage conversion circuit based on the voltage and adjusting a duty cycle of a switch in the target voltage conversion circuit to turn on or off the switch in the target voltage conversion circuit so as to reduce a current or an input power of the target voltage conversion circuit when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit. control This may include.

[0017] In this application, a photovoltaic panel may be connected to a load as a DC power source via a photovoltaic inverter. The photovoltaic inverter may convert DC energy provided by the photovoltaic panel into AC energy and provide the AC energy to the load. Here, the photovoltaic inverter may include an inverter circuit and a plurality of voltage conversion circuits. The DC power source may include a plurality of groups of photovoltaic panels (each group of photovoltaic panels may include one photovoltaic panel or multiple photovoltaic panels). Each group of photovoltaic panels may be connected to the inverter circuit via one voltage conversion circuit. The voltage conversion circuit may convert the DC voltage provided by the photovoltaic panel into AC energy and provide the AC energy to the load. Here, the photovoltaic inverter may include an inverter circuit and a plurality of voltage conversion circuits. The DC power source may include a plurality of groups of photovoltaic panels (each group of photovoltaic panels may include one photovoltaic panel or multiple photovoltaic panels). Each group of photovoltaic panels may be connected to the inverter circuit via one voltage conversion circuit. S The photovoltaic inverter may convert the DC energy into AC energy through an inverter circuit, so that the AC voltage output by the photovoltaic inverter can be adapted to loads in multiple voltage ranges. In an application scenario involving multiple groups of photovoltaic panels, there are differences between the groups of photovoltaic panels (e.g., different lengths, different shapes, or different light intensities). Therefore, the output voltage of the photovoltaic panels connected to the voltage conversion circuit (i.e., the input voltage of the voltage conversion circuit) and the balance S When the difference between the input voltage and the output voltage is too large, the input current in the voltage conversion circuit is usually high. As a result, overvoltage (too large voltage difference), overcurrent (too high current), or overheating (too high temperature) may cause failure or damage to elements in the voltage conversion circuit (e.g., switches in the voltage conversion circuit). Here, the photovoltaic inverter may further include a control circuit and an acquisition circuit. The acquisition circuit may acquire power supply parameters of the photovoltaic inverter (e.g., input voltage and / or output voltage of the voltage conversion circuit, input current and / or output current of the voltage conversion circuit, temperature of the voltage conversion circuit, balance, etc.). SThe control circuit may detect the input and output voltages of the inverter circuit, the input and output currents of the inverter circuit, and the temperature of the inverter circuit. Here, the control circuit may determine the operating state of the photovoltaic inverter based on the power supply parameters of the photovoltaic inverter. Here, an example is used in which one (or more) voltage conversion circuits that need to be controlled by the control circuit are the target voltage conversion circuits. The control circuit may detect the input and output voltages of the target voltage conversion circuit. S After the current threshold of the target voltage conversion circuit is obtained, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the control circuit adjusts the duty cycle of the switch in the target voltage conversion circuit (e.g., reduces the duty cycle of the switch in the target voltage conversion circuit) to turn on or off the switch in the target voltage conversion circuit so as to reduce the current or input power of the target voltage conversion circuit, in order to protect the operational safety of the voltage conversion circuit. control possible.

[0018] According to this application, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the photovoltaic inverter can adjust the duty cycle of the switch through the control circuit to reduce the input power of the voltage conversion circuit, thereby improving the stability and power supply efficiency of the photovoltaic inverter while ensuring the safety of the power supply. The structure is simple, and the method is straightforward and has high applicability.

[0019] Referring to the second aspect, in a first possible implementation, the input voltage and the balance of the target voltage conversion circuit are S Adjusting a current threshold of the target voltage conversion circuit based on the voltage The temperature of the target voltage conversion circuit is detected, and when the temperature of the target voltage conversion circuit is equal to or higher than a temperature threshold, the input voltage and balance of the target voltage conversion circuit are controlled. S and adjusting a current threshold of the target voltage conversion circuit to a first current threshold based on the voltage.

[0020] It can be understood that the control circuit can determine the operating state of the target voltage conversion circuit in a number of ways, and can further determine whether the input power (or input current) of the target voltage conversion circuit needs to be controlled. In other words, the control circuit can determine the operating state of the target voltage conversion circuit in a number of ways, and can further determine whether the duty cycle of the switch in the target voltage conversion circuit needs to be adjusted. For example, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the target voltage conversion circuit can be considered to be in an operating state in which the input power needs to be reduced (or, in other words, the switch in the target voltage conversion circuit is operating in a harsh environment and will be damaged at a high risk if it continues to operate). In this case, the control circuit needs to reduce the input current and / or input power of the target voltage conversion circuit. Here, when the operating temperature of the switch in the target voltage conversion circuit is different, the input current that the switch can withstand may be different even if the voltage difference borne by the switch is the same. For example, when the operating temperature of the switch in the target voltage conversion circuit is high (for example, the temperature of the target voltage conversion circuit is equal to or higher than a temperature threshold), the control circuit SThe maximum input current (e.g., a first current threshold) that the switch in the target voltage conversion circuit can withstand may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., based on the corresponding nominal current when various models of switches bear different voltage differences), or based on a current threshold acquired by the photovoltaic power inverter in a manner such as acquisition, collection, reception, detection, or storage. For example, the photovoltaic power inverter or an external central control system may calculate a curve of a corresponding current threshold when the switch bears different voltage differences at a specific operating temperature or a specific operating temperature range (e.g., a first operating temperature range equal to or greater than the temperature threshold) in the operation process (or design process) of the voltage conversion circuit. Also, the control circuit may obtain the first current threshold based on the curve. The first current threshold may be specifically set based on an application scenario. It may be understood that the first current threshold here may be one current, multiple discrete currents, or a current range including multiple discrete currents or continuous currents.

[0021] In this application, when the operating temperature of the switch in the target voltage conversion circuit is high (e.g., the temperature of the target voltage conversion circuit is equal to or higher than a temperature threshold), if the input current of the switch in the target voltage conversion circuit is equal to or higher than a first current threshold, it indicates that the target voltage conversion circuit is in an operating state in which the target voltage conversion circuit needs to be adjusted, and the control circuit may reduce the duty cycle of the switch in the target voltage conversion circuit to further reduce the input power of the target voltage conversion circuit, thereby avoiding the elements in the target voltage conversion circuit from being damaged by overheating and improving the safety of the target voltage conversion circuit. Also, the control circuit does not completely cut off the input electric energy of the target voltage conversion circuit. This ensures the efficiency of electric energy transmission on the basis of ensuring safety.

[0022] Referring to the first possible implementation of the second aspect, in the second possible implementation, after detecting the temperature of the target voltage conversion circuit, the method further includes: When the temperature of the target voltage conversion circuit is below the temperature threshold, the input voltage and balance S and adjusting a current threshold of the target voltage conversion circuit to a second current threshold based on the voltage, the second current threshold being greater than or equal to the first current threshold.

[0023] It can be understood that the control circuit can determine the operating state of the target voltage conversion circuit in a number of ways, and can further determine whether the input power (or input current) of the target voltage conversion circuit needs to be controlled. In other words, the control circuit can determine the operating state of the target voltage conversion circuit in a number of ways, and can further determine whether the duty cycle of the switch in the target voltage conversion circuit needs to be adjusted. For example, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the target voltage conversion circuit can be considered to be in an operating state in which the input power needs to be reduced (or, in other words, the switch in the target voltage conversion circuit is operating in a harsh environment and will be damaged at a high risk if it continues to operate). In this case, the control circuit needs to reduce the input current and / or input power of the target voltage conversion circuit. Here, when the operating temperature of the switch in the target voltage conversion circuit is different, the input current that the switch can withstand may be different even if the voltage difference borne by the switch is the same. For example, when the operating temperature of the switch in the target voltage conversion circuit is low (for example, the temperature of the target voltage conversion circuit is below a temperature threshold), the control circuit may reduce the voltage difference borne by the switch in the target voltage conversion circuit (for example, the input voltage and the balance SThe second current threshold may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., the difference between the first and second voltage thresholds). Here, the second current threshold is smaller than the first voltage threshold. The value of the second current threshold may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., the corresponding nominal current when various models of switches bear different voltage differences), or may be determined based on the current threshold obtained by the photovoltaic power inverter in a manner such as acquisition, collection, reception, detection, or storage. For example, the photovoltaic power inverter or an external central control system may calculate a corresponding current threshold curve when the switch bears different voltage differences at a specific operating temperature or a specific operating temperature range (e.g., a second operating temperature range lower than the temperature threshold) in the operation process (or design process) of the voltage conversion circuit. Also, the control circuit may obtain the second current threshold based on the curve. The second current threshold may be specifically set based on the application scenario. It can be appreciated that the second current threshold herein can be a single current, a number of discrete currents, or a range of currents including a number of discrete currents or a continuous current.

[0024] In this application, when the operating temperature of the switch in the target voltage conversion circuit is low (e.g., the temperature of the target voltage conversion circuit is below the temperature threshold), if the input current of the switch in the target voltage conversion circuit is equal to or greater than the second current threshold, it indicates that the target voltage conversion circuit is in an operating state in which the target voltage conversion circuit needs to be adjusted, and the control circuit may reduce the duty cycle of the switch in the target voltage conversion circuit to further reduce the input power of the target voltage conversion circuit, thereby avoiding the elements in the target voltage conversion circuit from being damaged by overheating and improving the safety of the target voltage conversion circuit. Also, the control circuit does not completely cut off the input electric energy of the target voltage conversion circuit. This ensures the efficiency of electric energy transmission on the basis of ensuring safety.

[0025] With reference to the second possible implementation of the second aspect, in a third possible implementation, the input voltage and the balance of the target voltage conversion circuit are S After adjusting the current threshold of the target voltage conversion circuit based on the voltage, the method further comprises: When an input current of the target voltage conversion circuit is equal to or greater than a current threshold of the target voltage conversion circuit, a switching modulation signal is generated based on the input current of the target voltage conversion circuit and the current threshold of the target voltage conversion circuit, and a duty cycle of a switch in the target voltage conversion circuit is controlled based on the switching modulation signal to turn on or off the switch in the target voltage conversion circuit. control This may include.

[0026] Here, a control circuit (e.g., a current regulation loop (e.g., a proportional regulation circuit or a proportional-integral regulation circuit) and a drive control circuit, or other circuit having a current regulation function and a drive control function) generates a switching modulation signal based on the input current of the target voltage conversion circuit and the current threshold of the target voltage conversion circuit to control the duty cycle of the switch in the target voltage conversion circuit. adjustment For example, the control circuit may be configured to generate a switching modulation signal PWM Alternatively, the driving pulse signal can be generated as a switching modulation signal based on a PWM wave, where the switching modulation signal determines the duty cycle of a switch in the target voltage conversion circuit. adjustment and may further control the input current and / or input power of the target voltage conversion circuit. For example, the control circuit may reduce the duty cycle of a switch in the target voltage conversion circuit to reduce the input current of the target voltage conversion circuit and reduce the input power of the target voltage conversion circuit. It may be understood that the control circuit provided in this application may include a switching modulation signal, DPWM A wave may be used, and another PWM wave (e.g., SWM wave, THIPWM Waves, or CBPWMThe switching modulation signal can be a driving pulse signal generated based on these PWM waves. It has a wide range of application and good control effect.

[0027] With reference to the second embodiment or any possible implementation of the second embodiment, in a fourth possible implementation, the input voltage and the balance of the target voltage conversion circuit are S After adjusting the current threshold of the target voltage conversion circuit based on the voltage, the method further comprises: The duty cycle of the switch in the target voltage conversion circuit is adjusted to turn on or off the switch in the target voltage conversion circuit so that the input power of the target voltage conversion circuit remains at the maximum target input power when the input current of the target voltage conversion circuit is less than a current threshold of the target voltage conversion circuit. control This may include.

[0028] Here, when the input current of the target voltage conversion circuit is less than a current threshold (e.g., a third current threshold) of the target voltage conversion circuit, the target voltage conversion circuit may be considered to be in an operating state in which the input power does not need to be reduced (in other words, the switch in the target voltage conversion circuit is operating in a safe environment with a low risk of damage). In this case, the control circuit may adjust the duty cycle of the switch in the target voltage conversion circuit so that the input power of the target voltage conversion circuit remains at the maximum target input power (e.g., the photovoltaic panel connected to the target voltage conversion circuit operates at the maximum power point). Here, the value of the third current threshold may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., based on the corresponding nominal current when various models of switches bear different voltage differences), or may be determined based on a current threshold obtained by the photovoltaic inverter in a manner such as acquisition, collection, reception, detection, or storage. For example, the photovoltaic power inverter or an external central control system may calculate a corresponding current threshold curve when the switch bears different voltage differences at a specific operating temperature or a specific operating temperature range (e.g., a first operating temperature range equal to or greater than a temperature threshold, or a second operating temperature range equal to or less than a temperature threshold) during the operation (or design) of the voltage conversion circuit. The control circuit may obtain a third current threshold based on the curve. The third current threshold may be specifically set based on an application scenario. It may be understood that the third current threshold here may be one current, multiple discrete currents, or a current range including multiple discrete currents or continuous currents. For example, in a first operating temperature range equal to or greater than a temperature threshold, the third current threshold may be equal to or less than the first current threshold. In another example, in a second operating temperature range equal to or less than a temperature threshold, the third current threshold may be equal to or less than the second current threshold. When the third voltage threshold is smaller than the first current threshold (or the second current threshold), the solar power inverter can avoid repeatedly decreasing or increasing the input power of the target voltage conversion circuit via the control circuit when the input current of the target voltage conversion circuit is not stably smaller than the first current threshold (or the second current threshold).In other words, when the third voltage threshold is less than the first current threshold (or the second current threshold), after the input current of the target voltage conversion circuit is stable (e.g., stable and less than the third current threshold), the target voltage conversion circuit of the solar power inverter may be in an operating state where the input power does not need to be reduced (or, in other words, the switches in the target voltage conversion circuit are operating in a safe environment with low risk of damage). In this case, the control circuit may adjust the duty cycle of the switches in the target voltage conversion circuit so that the input power of the target voltage conversion circuit remains at the maximum target input power (e.g., the solar panel connected to the target voltage conversion circuit operates at the maximum power point). This improves power supply efficiency.

[0029] Referring to the second embodiment or any of the possible implementations of the second embodiment, in a fifth possible implementation, the inverter circuit may include a switch. S After detecting the voltage, the method further comprises: B S Adjusting the duty cycle of a switch in the inverter circuit to turn on or off a switch in the inverter circuit so as to reduce the output power of the inverter circuit when the voltage is equal to or greater than the bus voltage threshold. control This may include.

[0030] It can be appreciated that the control circuit can determine the operating state of the solar power inverter in a number of ways, and can further determine whether the output power (or output current) of the solar power inverter (e.g., inverter circuit) needs to be controlled. SWhen the voltage is equal to or greater than the bus voltage threshold, the inverter circuit may be considered to be in an operating condition that requires a reduced output power (or, in other words, the elements in the photovoltaic inverter are operating in a harsh environment and are at high risk of being damaged if they continue to operate). In this case, the control circuitry needs to reduce the output current and / or output power of the inverter circuit. It may be understood that the bus voltage threshold here may be a voltage, a number of discrete voltages, or a voltage range that includes a number of discrete or continuous voltages.

[0031] In this application, S High voltage (e.g. S When the voltage is equal to or greater than the bus voltage threshold, it indicates that the photovoltaic inverter is in an operating state where the output power needs to be reduced. The control circuit can reduce the duty cycle of each switch in the inverter circuit to further reduce the output power of the inverter circuit, to prevent the elements in the photovoltaic inverter from being damaged by overheating, and further improve the safety of the power supply. [Brief description of the drawings]

[0032] [Figure 1] FIG. 1 is a schematic diagram of an application scenario of a photovoltaic inverter according to an embodiment of the present application. [Diagram 2] FIG. 2 is a schematic diagram of a photovoltaic panel layout scenario according to an embodiment of the present application. [Diagram 3] FIG. 1 is a schematic diagram of a structure of a photovoltaic inverter according to an embodiment of the present application. [Figure 4] FIG. 2 is a schematic diagram of a volt-ampere characteristic of a photovoltaic panel according to one embodiment of the present application. [Diagram 5] 2 is a schematic diagram of a current threshold curve of a voltage conversion circuit according to an embodiment of the present application; [Figure 6] FIG. 2 is a schematic diagram of another structure of a solar power inverter according to an embodiment of the present application. [Figure 7]FIG. 1 is a schematic diagram of a structure of a solar power generation system according to an embodiment of the present application. [Figure 8] 1 is a schematic flowchart of a power control method according to an embodiment of the present application. [Figure 9] 4 is another schematic flowchart of a power control method according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] In the technical field of power electronics, an inverter circuit in a photovoltaic inverter is usually used to convert DC energy to AC energy so that electrical energy can be transmitted between a power source and a load. For example, in the field of a photovoltaic power source, a photovoltaic inverter can convert DC energy output by a DC power source (e.g., a photovoltaic panel) into AC energy and provide the AC energy for use by a load or a power grid. In general, a control circuit (e.g., an MPPT control circuit) in a photovoltaic inverter controls the output current of the photovoltaic panel (i.e., the input current of the photovoltaic inverter) based on the output voltage of the photovoltaic panel (i.e., the input voltage of the photovoltaic inverter), so that the photovoltaic panel outputs electrical energy to the load with maximum power. In practical application, a photovoltaic inverter usually converts the DC voltage provided by each group of photovoltaic panels into a DC bus voltage (e.g., converts the voltage of each group of photovoltaic panels into a DC bus voltage) by using multiple voltage conversion circuits. S The voltage converter converts the DC energy to AC energy by boosting the DC voltage, and then converts it to AC energy by using an inverter circuit to accommodate different load voltages. There are differences between groups of photovoltaic panels (e.g., different lengths or different light intensities). Therefore, the output voltage of the photovoltaic panels connected to the voltage converter circuit (i.e., the input voltage of the voltage converter circuit) and the SWhen the difference between the voltage and the input current is excessively large, the input current in the voltage conversion circuit is usually high. As a result, the elements in the voltage conversion circuit (e.g., the switches in the voltage conversion circuit) may be damaged or broken due to overvoltage, overcurrent, or overheating. Therefore, when the voltage conversion circuit operates, it is necessary to control the input power (or a parameter such as the input current) of the voltage conversion circuit to ensure the power supply safety of each element in the photovoltaic power generation inverter.

[0034] This application provides a photovoltaic inverter and a power control method. When the input current of a target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the duty cycle of the switch can be adjusted through a control circuit to reduce the input power of the voltage conversion circuit, thereby improving the stability and power supply efficiency of the photovoltaic inverter while ensuring the safety of the power supply. The structure is simple, and the method is simple and has high applicability.

[0035] The photovoltaic inverter provided in this application can be applied to multiple application fields, such as the field of new energy power generation, the field of traditional peak load regulation and frequency regulation for power generation, the field of power supply to important equipment, and the field of new energy vehicles. This can be specifically determined based on the actual application scenario, and is not limited here. The photovoltaic inverter provided in this application can be applied to different power supply systems, such as energy storage systems, uninterruptible power supply systems, and motor drive systems. This can be specifically determined based on the actual application scenario, and is not limited here. The photovoltaic inverter provided in this application can be applied to different application scenarios, such as the application scenario of controlling an inverter in a light energy power supply environment, the application scenario of controlling an inverter in a new energy power supply environment, or other application scenarios. In the following, the application scenario of controlling a photovoltaic inverter in a light energy power supply environment is used as an example for explanation, and the details will not be described again below.

[0036] Please refer to FIG. 1. FIG. 1 is a schematic diagram of an application scenario of a photovoltaic inverter according to an embodiment of this application. In a photovoltaic power system based on light energy power supply, as shown in FIG. 1, the photovoltaic power system includes a photovoltaic inverter 1, a power source 2 including a plurality of groups of photovoltaic panels (e.g., photovoltaic panel a to photovoltaic panel n), and a load 3. The power source 2 can be connected to the load 3 through the photovoltaic inverter 1. In some possible implementations, the photovoltaic inverter 1 can convert DC energy provided by the power source 2 including a plurality of groups of photovoltaic panels into AC energy and provide the AC energy to the load. It can be understood that the power source 2 provided in this application can be applied to application scenarios in which power is supplied to various types of utilization equipment, for example, the power is supplied to base station equipment in a remote area with no or poor mains supply, or the power is supplied to household equipment (e.g., refrigerator or air conditioner, etc.). This can be specifically determined based on the actual application scenario, and is not limited here. It can be further understood that the load 3 in FIG. 2 can include a power grid. The power grid here may include utilization devices and power transmission devices, such as power transmission lines, power transmission stations, communication base stations, or household appliances. Here, the photovoltaic power inverter 1 includes an inverter circuit 11 and a plurality of voltage conversion circuits (e.g., voltage conversion circuit a to voltage conversion circuit n). Each group of photovoltaic power panels may be connected to the inverter circuit 11 via one corresponding voltage conversion circuit. The voltage conversion circuits convert the DC voltage provided by the photovoltaic power panels into a buck converter. S The solar power inverter may convert the DC energy to AC energy through an inverter circuit, so that the AC voltage output by the solar power inverter can accommodate loads within multiple voltage ranges.

[0037] In some possible implementations, please refer to FIG. 2 together for details. FIG. 2 is a schematic diagram of a layout scenario of a photovoltaic panel according to an embodiment of this application. As shown in FIG. 2, the gray part is the position where the photovoltaic panel is placed (e.g., the top of a house or building). In an application scenario including multiple groups of photovoltaic panels, there exists a difference between the groups of photovoltaic panels (e.g., the light intensity of the photovoltaic panel placed on the top is different, as shown by part (a), part (b), and part (c) of FIG. 2, and the length and shape of the photovoltaic panel placed on the top are different, as shown by part (d), part (e), and part (f) of FIG. 2). Therefore, the output voltage of the photovoltaic panel connected to the voltage conversion circuit (i.e., the input voltage of the voltage conversion circuit) and the balance are different. S When the difference between the voltages is excessively large, the input current in the voltage conversion circuit is usually high. As a result, overvoltage (excessively large voltage difference), overcurrent (excessively high current), or overheating (excessively high temperature) may cause failure or damage to elements in the voltage conversion circuit (e.g., switches in the voltage conversion circuit). Therefore, when the solar power inverter 1 operates, it is necessary to control the input power of the voltage conversion circuit to ensure the power supply safety of each element in the solar power inverter. Here, the solar power inverter 1 may further include a control circuit 13 and an acquisition circuit 12. The acquisition circuit 12 acquires power supply parameters of the solar power inverter (e.g., input voltage and / or output voltage of the voltage conversion circuit, input current and / or output current of the voltage conversion circuit, temperature of the voltage conversion circuit, balance, etc.). S The control circuit 13 may detect the input voltage and / or output voltage of the inverter circuit 11, the input current and / or output current of the inverter circuit 11, and the temperature of the inverter circuit 11). Here, the control circuit 13 may determine the operating state of the solar power inverter based on the power supply parameters of the solar power inverter. Here, an example is used in which one (or more) voltage conversion circuits that need to be controlled by the control circuit 13 are target voltage conversion circuits. The control circuit 13 detects the input voltage and balance of the target voltage conversion circuit. SAfter the current threshold of the target voltage conversion circuit is obtained, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, in order to protect the operation safety of the voltage conversion circuit, the control circuit 13 adjusts the duty cycle of the switch in the target voltage conversion circuit (e.g., reduces the duty cycle of the switch in the target voltage conversion circuit) to turn on or off the switch in the target voltage conversion circuit so as to reduce the input power of the target voltage conversion circuit. control This improves the stability and power supply efficiency of the photovoltaic inverter while ensuring the safety of the power supply. The structure is simple, the method is straightforward and has high applicability.

[0038] In the following, the photovoltaic inverter provided in this application and the working principle of the photovoltaic inverter will be described by using an example with reference to Figs. 3 to 9.

[0039] Please refer to FIG. 3. FIG. 3 is a schematic diagram of a structure of a photovoltaic inverter according to an embodiment of this application. As shown in FIG. 3, a photovoltaic system includes a power source, a photovoltaic inverter, and a load. The photovoltaic inverter includes an inverter circuit 101, a plurality of voltage conversion circuits, a plurality of acquisition circuits, and a control circuit 103. One voltage conversion circuit may include at least one switch. Here, in order to make the legend connection more simple and clear, in the accompanying drawings of this application, the plurality of acquisition circuits are integrated into an acquisition circuit module to show the connection relationship and detection relationship of the plurality of acquisition circuits and to explain the operation principle of the plurality of acquisition circuits. As shown in FIG. 3, as an example, the plurality of acquisition circuits are shown as an acquisition circuit 102. In a specific implementation, the acquisition circuit in each figure may be divided into a plurality of acquisition circuits for arrangement. Details will not be described below. Here, one end of each voltage conversion circuit may be configured to be connected to each of a plurality of groups of photovoltaic panels. The other end of each voltage conversion circuit may be connected to a buffer. SThe power supply 102 may be connected in parallel and then connected to a load via an inverter circuit 101. The power supply 102 may be connected to a control circuit 103 to control a plurality of voltage conversion circuits and a load. S A control circuit 103 is connected to the switches in each voltage conversion circuit. Here, the acquisition circuit 102 detects the input voltage and the balance of the target voltage conversion circuit. S The target voltage conversion circuit may be any one or more of the plurality of voltage conversion circuits. Here, the control circuit 103 may be configured to detect the input voltage and balance of the target voltage conversion circuit. S Here, the control circuit 103 adjusts the duty cycle of the switch in the target voltage conversion circuit to turn on or off the switch in the target voltage conversion circuit so as to reduce the current or input power of the target voltage conversion circuit when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit. control The device may be configured to:

[0040] In this application, the voltage conversion circuit may be various circuits having a voltage conversion function. In FIG. 3, for the purpose of explanation, only an example in which the voltage conversion circuit is a boost circuit is used. Here, the boost circuit may include a switch, an inductor, and a diode. One end of the inductor is connected to a power source (i.e., a solar panel). The other end of the inductor is connected to a ballast through a switch and a diode. S In some application scenarios, the boost circuit is SThe parallel connected bus capacitors can be reused to stabilize the output voltage of the boost circuit through the bus capacitor. When the switch of the boost circuit is turned on, the power source charges the inductor, the boost circuit supplies power to the inverter circuit 101 (and the load) through the bus capacitor, and the diode prevents the electric energy from flowing together in the bus capacitor. When the switch of the boost circuit is turned off, the power source and the inductor charge the bus capacitor, and the boost circuit boosts the input voltage to the voltage of the bus capacitor for output. It can be understood that, ignoring the voltage of the switch of the boost circuit, the input voltage Vin of the boost circuit, the output voltage Vout of the boost circuit, and the duty cycle N of the switch of the boost circuit satisfy Vin / Vout=1 / (1-N). Here, the acquisition circuit 102 acquires power supply parameters of the photovoltaic power inverter (e.g., input and / or output voltage of the voltage conversion circuit, input and / or output current of the voltage conversion circuit, temperature of the voltage conversion circuit, S The control circuit 103 may detect the input and / or output voltages of the inverter circuit 101, the input and / or output currents of the inverter circuit 101, and the temperature of the inverter circuit 101). Furthermore, it can be understood that the control circuit 103 may determine the operation state of the solar power inverter based on the power supply parameters of the solar power inverter. Here, an example is used in which the voltage conversion circuit (or circuits) that need to be controlled by the control circuit 103 is a target voltage conversion circuit. The control circuit 103 detects the input and output voltages of the target voltage conversion circuit. SThe current threshold of the target voltage conversion circuit may be adjusted based on the voltage and the current threshold of the target voltage conversion circuit. For details, please refer to FIG. 4 together. FIG. 4 is a schematic diagram of a volt-ampere characteristic of a photovoltaic panel according to an embodiment of this application. As shown in FIG. 4, after the current threshold of the target voltage conversion circuit is obtained, it is assumed that the output parameters (e.g., output current and output voltage) of the group of photovoltaic panels connected to the target voltage conversion circuit correspond to point B on the volt-ampere characteristic curve of the group of photovoltaic panels in FIG. 4. When the output current Ib of the photovoltaic power generation panel corresponding to point B (i.e., the input current of the target voltage conversion circuit) is less than the current threshold of the target voltage conversion circuit, in order to ensure the power supply efficiency of the system, the control circuit 103 (e.g., the MPPT control circuit) in the photovoltaic power generation inverter adjusts the duty cycle of the switch in the target voltage conversion circuit based on the output voltage of the photovoltaic power generation panel (i.e., the input voltage of the photovoltaic power generation inverter) to turn on or off the switch in the target voltage conversion circuit, so as to increase the output current of the photovoltaic power generation panel to Ia corresponding to point A (i.e., increase the input current of the photovoltaic power generation inverter to Ia), so that the photovoltaic power generation panel outputs electrical energy at the maximum power (i.e., the power shown at point A). control 4, when the output current Ib of the photovoltaic power generation panel corresponding to point B (i.e., the input current of the target voltage conversion circuit) is equal to or greater than the current threshold of the target voltage conversion circuit, in order to ensure the operational safety of the voltage conversion circuit, the control circuit 103 adjusts the duty cycle of the switch in the target voltage conversion circuit (e.g., reduces the duty cycle of the switch in the target voltage conversion circuit) to turn on or off the switch in the target voltage conversion circuit so as to reduce the output current of the photovoltaic power generation panel to Ic corresponding to point C (i.e., reduces the input current of the photovoltaic power generation inverter to Ic) in order to reduce the input power of the target voltage conversion circuit (i.e., reduces the input power of the target voltage conversion circuit to the power shown at point C). control possible.

[0041] According to this application, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the photovoltaic inverter can adjust the duty cycle of the switch through the control circuit 103 to reduce the input power of the voltage conversion circuit, thereby improving the stability and power supply efficiency of the photovoltaic inverter while ensuring the safety of the power supply. The structure is simple, the method is straightforward and has high applicability.

[0042] In some possible implementations, the acquisition circuit 102 may be further configured to detect the temperature of the target voltage conversion circuit. The control circuit 103 may further detect the input voltage and balance of the target voltage conversion circuit when the temperature of the target voltage conversion circuit is equal to or greater than a temperature threshold. SThe control circuit 103 may be configured to adjust the current threshold of the target voltage conversion circuit to the first current threshold based on the voltage and the input power (or input current) of the target voltage conversion circuit. It can be understood that the control circuit 103 can determine the operation state of the target voltage conversion circuit in a number of ways, and further determine whether the input power (or input current) of the target voltage conversion circuit needs to be controlled. In other words, the control circuit 103 can determine the operation state of the target voltage conversion circuit in a number of ways, and further determine whether the duty cycle of the switch in the target voltage conversion circuit needs to be adjusted. For example, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the target voltage conversion circuit may be considered to be in an operation state in which the input power needs to be reduced (or, in other words, the switch in the target voltage conversion circuit is operating in a harsh environment and will be damaged at a high risk if it continues to operate). In this case, the control circuit 103 needs to reduce the input current and / or the input power of the target voltage conversion circuit. Here, when the operating temperatures of the switches in the target voltage conversion circuit are different, the input current that the switches can withstand may be different even if the voltage difference borne by the switches is the same. Please refer to FIG. 5 for details. FIG. 5 is a schematic diagram of a current threshold curve of a voltage conversion circuit according to an embodiment of this application. As shown in FIG. 5, a photovoltaic power generation inverter or an external central control system may calculate, in the operation process (or design process) of a voltage conversion circuit, a curve of a corresponding current threshold Ith when a switch bears a different voltage difference D(V) at a specific operating temperature or a specific operating temperature range (e.g., a first operating temperature range equal to or greater than a temperature threshold), as Curve 1. Also, the control circuit 103 may obtain a first current threshold based on the curve. For example, when the operating temperature of a switch in the target voltage conversion circuit is high (e.g., the temperature of the target voltage conversion circuit is equal to or greater than a temperature threshold), the control circuit 103 may calculate a voltage difference (e.g., the input voltage and balance voltage of the target voltage conversion circuit) borne by the switch in the target voltage conversion circuit. SThe maximum input current (e.g., a first current threshold) that the switch in the target voltage conversion circuit can withstand may be determined based on the difference between the voltages of the switch and the voltages of the target voltage conversion circuit. The value of the first current threshold may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., based on the corresponding nominal current when various models of switches bear different voltage differences), or may be determined based on a current threshold obtained by the photovoltaic power inverter in a manner such as acquisition, collection, reception, detection, or storage. The first current threshold may be specifically set based on the application scenario. It may be understood that the first current threshold here may be one current, multiple discrete currents, or a current range including multiple discrete currents or continuous currents.

[0043] In this application, when the operating temperature of the switch in the target voltage conversion circuit is high (e.g., the temperature of the target voltage conversion circuit is equal to or higher than the temperature threshold), if the input current of the switch in the target voltage conversion circuit is equal to or higher than the first current threshold, it indicates that the target voltage conversion circuit is in an operating state in which the target voltage conversion circuit needs to be adjusted, and the control circuit 103 may reduce the duty cycle of the switch in the target voltage conversion circuit to further reduce the input power of the target voltage conversion circuit, thereby avoiding the elements in the target voltage conversion circuit from being damaged by overheating and improving the safety of the target voltage conversion circuit. In addition, the control circuit 103 does not completely cut off the input electric energy of the target voltage conversion circuit. This ensures the efficiency of electric energy transmission on the basis of ensuring safety.

[0044] In some possible implementations, the control circuit 103 further controls the input voltage and the balance of the target voltage conversion circuit when the temperature of the target voltage conversion circuit is below a temperature threshold. SThe control circuit 103 may be configured to adjust the current threshold of the target voltage conversion circuit to a second current threshold based on the voltage. The second current threshold is equal to or greater than the first current threshold. It may be understood that the control circuit 103 may determine the operating state of the target voltage conversion circuit in a number of ways, and may further determine whether the input power (or input current) of the target voltage conversion circuit needs to be controlled. In other words, the control circuit 103 may determine the operating state of the target voltage conversion circuit in a number of ways, and may further determine whether the duty cycle of the switch in the target voltage conversion circuit needs to be adjusted. For example, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the target voltage conversion circuit may be considered to be in an operating state in which the input power needs to be reduced (or, in other words, the switch in the target voltage conversion circuit is operating in a harsh environment and will be damaged at a high risk if it continues to operate). In this case, the control circuit 103 needs to reduce the input current and / or the input power of the target voltage conversion circuit. Here, when the operating temperatures of the switches in the target voltage conversion circuit are different, the input current that the switches can withstand may be different even if the voltage difference borne by the switches is the same. Still as shown in FIG. 5, the photovoltaic power generation inverter or an external central control system may calculate, in the operation process (or design process) of the voltage conversion circuit, a curve of the corresponding current threshold Ith when the switch bears a different voltage difference D(V) at a specific operating temperature or a specific operating temperature range (e.g., a second operating temperature range lower than the temperature threshold), to be curve 2. Also, the control circuit 103 may obtain a second current threshold based on the curve. For example, when the operating temperature of the switch in the target voltage conversion circuit is low (e.g., the temperature of the target voltage conversion circuit is lower than the temperature threshold), the control circuit 103 may calculate the voltage difference (e.g., the input voltage and balance voltage of the target voltage conversion circuit) borne by the switch in the target voltage conversion circuit. SThe second current threshold may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., the difference between the first and second voltages). Here, the second current threshold is smaller than the first voltage threshold. Note that the value of the second current threshold may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., based on the corresponding nominal current when various models of switches bear different voltage differences), or based on the current threshold obtained by the photovoltaic power inverter in a manner such as acquisition, collection, reception, detection, or storage. The second current threshold may be specifically set based on the application scenario. It may be understood that the second current threshold here may be one current, multiple discrete currents, or a current range including multiple discrete currents or continuous currents.

[0045] In this application, when the operating temperature of the switch in the target voltage conversion circuit is low (e.g., the temperature of the target voltage conversion circuit is below the temperature threshold), if the input current of the switch in the target voltage conversion circuit is equal to or greater than the second current threshold, it indicates that the target voltage conversion circuit is in an operating state in which the target voltage conversion circuit needs to be adjusted, and the control circuit 103 may reduce the duty cycle of the switch in the target voltage conversion circuit to further reduce the input power of the target voltage conversion circuit, thereby avoiding the elements in the target voltage conversion circuit from being damaged by overheating and improving the safety of the target voltage conversion circuit. In addition, the control circuit 103 does not completely cut off the input electric energy of the target voltage conversion circuit. This ensures the efficiency of electric energy transmission on the basis of ensuring safety.

[0046] In some possible implementations, the control circuit 103 further generates a switching modulation signal based on the input current of the target voltage conversion circuit and the current threshold of the target voltage conversion circuit when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, and adjusts the duty cycle of the switch in the target voltage conversion circuit based on the switching modulation signal. adjustmentand turn on or off the switch in the target voltage conversion circuit. control Here, a control circuit 103 (e.g., a current regulation loop (e.g., a proportional regulation circuit or a proportional-integral regulation circuit) and a drive control circuit 103, or other circuits having a current regulation function and a drive control function) generates a switching modulation signal based on the input current of the target voltage conversion circuit and a current threshold of the target voltage conversion circuit to control the duty cycle of a switch in the target voltage conversion circuit. adjustment For example, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the control circuit 103 generates a reference value that is smaller than the current threshold based on the current threshold of the target voltage conversion circuit, and adjusts the duty cycle of the switch in the target voltage conversion circuit based on the switching modulation signal by using the input current of the target voltage conversion circuit as the variable that needs to be adjusted. adjustment In this case, the control circuit 103 may generate a switching modulation signal for adjusting the input current in the target voltage conversion circuit to be less than the current threshold value (i.e., the above-mentioned reference value) of the target voltage conversion circuit. PWM Alternatively, the driving pulse signal can be generated as a switching modulation signal based on a PWM wave, where the switching modulation signal determines the duty cycle of a switch in the target voltage conversion circuit. adjustment and may further control the input current and / or input power of the target voltage conversion circuit. For example, the control circuit 103 may reduce the duty cycle of a switch in the target voltage conversion circuit to reduce the input current of the target voltage conversion circuit and reduce the input power of the target voltage conversion circuit. It may be understood that the control circuit 103 provided in this application may include, as a switching modulation signal, DPWM A wave may be used, and another PWM wave (e.g., SWM wave, THIPWM Waves, or CBPWMThe switching modulation signal can be a driving pulse signal generated based on these PWM waves. It has a wide range of application and good control effect.

[0047] In some possible implementations, the control circuit 103 further adjusts the duty cycle of a switch in the target voltage conversion circuit to turn on or off a switch in the target voltage conversion circuit, so that the input power of the target voltage conversion circuit remains at a maximum target input power when the input current of the target voltage conversion circuit is less than a current threshold of the target voltage conversion circuit. controlRefer again to FIG. 4. After the current threshold of the target voltage conversion circuit is obtained, assume that the output parameters (e.g., output current and output voltage) of the group of photovoltaic panels connected to the target voltage conversion circuit correspond to point B on the volt-ampere characteristic curve of the group of photovoltaic panels in FIG. 4. When the output current Ib of the photovoltaic panel corresponding to point B (i.e., the input current of the target voltage conversion circuit) is less than the current threshold (e.g., the third current threshold) of the target voltage conversion circuit, the target voltage conversion circuit may be considered to be in an operating state in which the input power does not need to be reduced (in other words, the switch in the target voltage conversion circuit is operating in a safe environment with a low risk of damage). In this case, the control circuit 103 may adjust the duty cycle of the switch in the target voltage conversion circuit so that the input power of the target voltage conversion circuit remains at the maximum target input power (e.g., the photovoltaic panel connected to the target voltage conversion circuit operates at the maximum power point). Here, the value of the third current threshold may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., based on the corresponding nominal current when various models of switches bear different voltage differences), or based on the current threshold obtained by the photovoltaic inverter in a manner such as acquisition, collection, reception, detection, or storage. For example, the photovoltaic inverter or an external central control system may calculate a curve of the corresponding current threshold when the switch bears different voltage differences at a specific operating temperature or a specific operating temperature range (e.g., a first operating temperature range equal to or greater than the temperature threshold, or a second operating temperature range less than the temperature threshold) in the operation process (or design process) of the voltage conversion circuit. Also, the control circuit 103 may obtain the third current threshold based on the curve. The third current threshold may be specifically set based on the application scenario. It may be understood that the third current threshold here may be one current, multiple discrete currents, or a current range including multiple discrete currents or continuous currents. For example, in a first operating temperature range above the temperature threshold, the third current threshold may be less than or equal to the first current threshold.In another example, in a second operating temperature range below the temperature threshold, the third current threshold may be less than or equal to the second current threshold.

[0048] It can be understood that if the third voltage threshold is less than the first current threshold (or the second current threshold), the photovoltaic inverter can avoid repeatedly decreasing or increasing the input power of the target voltage conversion circuit via the control circuit 103 when the input current of the target voltage conversion circuit is not stable and less than the first current threshold (or the second current threshold). In other words, when the third voltage threshold is less than the first current threshold (or the second current threshold), after the input current of the target voltage conversion circuit is stable (e.g., stable and less than the third current threshold), the target voltage conversion circuit of the photovoltaic inverter can be in an operating state where the input power does not need to be reduced (or, in other words, the switches in the target voltage conversion circuit are operating in a safe environment with a low risk of damage). In this case, the control circuit 103 can adjust the duty cycle of the switches in the target voltage conversion circuit so that the input power of the target voltage conversion circuit remains at the maximum target input power (e.g., the photovoltaic panel connected to the target voltage conversion circuit operates at the maximum power point). This improves power supply efficiency.

[0049] In some possible implementations, the inverter circuit may include switches (e.g., multi-level inverter circuits and their topology circuits). Please refer to FIG. 6. FIG. 6 is a schematic diagram of another structure of a photovoltaic inverter according to an embodiment of this application. As shown in FIG. 6, the inverter circuit 201 includes two capacitors connected in series, four switches connected in series, and two diodes connected in anti-series. The connections and operation principles of the voltage conversion circuit, acquisition circuit 202, and control circuit 203 in FIG. 3 are the same as those of the voltage conversion circuit, acquisition circuit 102, and control circuit 103 in FIG. 3, and the details will not be described again here. Here, the control circuit 203 further includes a buffer circuit 204, a buffer circuit 206, and a buffer circuit 208. SThe duty cycle of the switches in the inverter circuit 201 is adjusted to turn on or off the switches in the inverter circuit 201 so as to reduce the output power of the inverter circuit 201 when the voltage is equal to or greater than the bus voltage threshold. control It can be appreciated that the control circuit 203 can determine the operating state of the solar power inverter in a number of ways, and can further determine whether the output power (or output current) of the solar power inverter (e.g., inverter circuit 201) needs to be controlled. For example, S When the voltage is equal to or greater than the bus voltage threshold, the inverter circuit 201 may be considered to be in an operating state that requires a reduction in output power (or, in other words, the elements in the photovoltaic inverter are operating in a harsh environment and are at high risk of being damaged if they continue to operate). In this case, the control circuit 203 needs to reduce the output current and / or output power of the inverter circuit 201. It may be understood that the bus voltage threshold here may be a voltage, multiple discrete voltages, or a voltage range that includes multiple discrete or continuous voltages.

[0050] In this application, S High voltage (e.g. Bus When the voltage is equal to or greater than the bus voltage threshold, it indicates that the photovoltaic inverter is in an operating state that requires reducing the output power. The control circuit 203 can reduce the duty cycle of each switch in the inverter circuit 201 to further reduce the output power of the inverter circuit 201, to prevent the elements in the photovoltaic inverter from being damaged by overheating, and further improve the safety of the power supply.

[0051] This application further provides a photovoltaic power generation system. Please refer to FIG. 7 together for details. FIG. 7 is a schematic diagram of a structure of a photovoltaic power generation system according to an embodiment of this application. As shown in FIG. 7, the photovoltaic power generation system may include a power supply and a photovoltaic power inverter. The photovoltaic power inverter here is applicable to the photovoltaic power inverter shown in FIG. 1-FIG. 6. In FIG. 7, only the photovoltaic power inverter shown in FIG. 3 is used as an example for explanation. It can be understood that the connection mode and operation principle of the inverter circuit 301, the voltage conversion circuit, the acquisition circuit 302, and the control circuit 303 in FIG. 7 are the same as those of the inverter circuit 101, the voltage conversion circuit, the acquisition circuit 102, and the control circuit 103 in FIG. 3. The details will not be described again here. In the photovoltaic power generation system shown in FIG. 7, the load here may be a power grid. The photovoltaic power generation system may further include a grid connection and off-grid wiring device 305. The photovoltaic inverter may provide power via grid connection and off-grid wiring devices 305 to utilization or transmission equipment within the power grid, such as power lines, power transmission stations, batteries, communication base stations, or household appliances.

[0052] In this application, the configuration modes of the photovoltaic inverter, the photovoltaic power system, and the functional modules in the photovoltaic power system are diversified, flexible, and adaptable to different power supply environments. Therefore, the diversity of the application scenarios of the photovoltaic power system is improved, and the adaptability of the photovoltaic power system is enhanced. In addition, according to any of the photovoltaic power systems or photovoltaic inverters shown in Figures 1-7, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the control circuit can adjust the duty cycle of the switch to reduce the input power of the voltage conversion circuit, thereby improving the stability and power supply efficiency of the photovoltaic inverter while ensuring the safety of the power supply. The structure is simple, and the method is straightforward and highly applicable. For ease of explanation, the following will use the structure of the photovoltaic inverter shown in Figure 3 as an example to describe the power control method provided in the embodiments of this application.

[0053] Please refer to FIG. 8. FIG. 8 is a schematic flow chart of a power control method according to this application. The control method provided in this application is applicable to a solar power generation system or a solar power generation inverter. The solar power generation system here may include an inverter circuit and a plurality of voltage conversion circuits. One end of each voltage conversion circuit is configured to be connected to a solar power generation panel. The other end of each voltage conversion circuit is configured to be connected to a buffer. S The solar power generation system and the solar power generation inverter are connected in parallel and then connected to a load via an inverter circuit. Here, the solar power generation system and the solar power generation inverter also include, but are not limited to, any of the solar power generation systems or the solar power generation inverters in the solar power generation systems shown in Figures 1 to 7. As shown in Figure 8, the power control method provided in this application includes the following steps.

[0054] S701: Input voltage of the target voltage conversion circuit, input current of the target voltage conversion circuit, and balance S Detect the voltage.

[0055] S702: Input voltage and balance of the target voltage conversion circuit S The current threshold of the target voltage conversion circuit is adjusted based on the voltage.

[0056] S703: When the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, adjust the duty cycle of the switch in the target voltage conversion circuit to turn on or off the switch in the target voltage conversion circuit so as to reduce the current or input power of the target voltage conversion circuit. control do.

[0057] In this application, a photovoltaic panel may be connected to a load as a DC power source via a photovoltaic inverter. The photovoltaic inverter may convert DC energy provided by the photovoltaic panel into AC energy and provide the AC energy to the load. Here, the photovoltaic inverter may include an inverter circuit and a plurality of voltage conversion circuits. The DC power source may include a plurality of groups of photovoltaic panels (each group of photovoltaic panels may include one photovoltaic panel or multiple photovoltaic panels). Each group of photovoltaic panels may be connected to the inverter circuit via one corresponding voltage conversion circuit. The voltage conversion circuit may convert the DC voltage provided by the photovoltaic panel into AC energy and provide the AC energy to the load. Here, the photovoltaic inverter may include an inverter circuit and a plurality of voltage conversion circuits. The DC power source may include a plurality of groups of photovoltaic panels (each group of photovoltaic panels may include one photovoltaic panel or multiple photovoltaic panels). Each group of photovoltaic panels may be connected to the inverter circuit via a corresponding voltage conversion circuit. S The photovoltaic inverter may convert the DC energy into AC energy through an inverter circuit, so that the AC voltage output by the photovoltaic inverter can be adapted to loads in multiple voltage ranges. In an application scenario involving multiple groups of photovoltaic panels, there are differences between the groups of photovoltaic panels (e.g., different lengths, different shapes, or different light intensities). Therefore, the output voltage of the photovoltaic panels connected to (one or some) voltage conversion circuits (i.e., the input voltage of the voltage conversion circuit) and the balance voltage may be calculated. S When the difference between the input voltage and the output voltage is too large, the input current in the voltage conversion circuit is usually high. As a result, overvoltage (too large voltage difference), overcurrent (too high current), or overheating (too high temperature) may cause failure or damage to elements in the voltage conversion circuit (e.g., switches in the voltage conversion circuit). Here, the photovoltaic inverter may further include a control circuit and an acquisition circuit. The acquisition circuit may acquire power supply parameters of the photovoltaic inverter (e.g., input voltage and / or output voltage of the voltage conversion circuit, input current and / or output current of the voltage conversion circuit, temperature of the voltage conversion circuit, balance, etc.). SThe control circuit may detect the input and output voltages of the inverter circuit, the input and output currents of the inverter circuit, and the temperature of the inverter circuit. Here, the control circuit may determine the operating state of the photovoltaic inverter based on the power supply parameters of the photovoltaic inverter. Here, an example is used in which one (or more) voltage conversion circuits that need to be controlled by the control circuit are the target voltage conversion circuits. The control circuit may detect the input and output voltages of the target voltage conversion circuit. S After the current threshold of the target voltage conversion circuit is obtained, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the control circuit adjusts the duty cycle of the switch in the target voltage conversion circuit (e.g., reduces the duty cycle of the switch in the target voltage conversion circuit) to turn on or off the switch in the target voltage conversion circuit so as to reduce the current or input power of the target voltage conversion circuit, in order to protect the operational safety of the voltage conversion circuit. control possible.

[0058] According to this application, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the photovoltaic inverter can adjust the duty cycle of the switch through the control circuit to reduce the input power of the voltage conversion circuit, thereby improving the stability and power supply efficiency of the photovoltaic inverter while ensuring the safety of the power supply. The structure is simple, and the method is straightforward and has high applicability.

[0059] In some possible implementations, please refer to FIG. 9. FIG. 9 is another schematic flowchart of a power control method according to the present application. As shown in FIG. 9, the input voltage of the target voltage conversion circuit, the input current of the target voltage conversion circuit, and the balance SAfter performing step S701 of detecting the voltage, the control circuit (or the photovoltaic power inverter) can determine a current threshold of the target voltage conversion circuit according to the input voltage of the target voltage conversion circuit and the input current of the target voltage conversion circuit. The power control method can further include the following steps:

[0060] S801: Detect the temperature of the target voltage conversion circuit.

[0061] S802: Determine whether the temperature of the target voltage conversion circuit is equal to or higher than the temperature threshold value. If the result of the determination is yes, step S803 is executed, and if the result of the determination is no, step S804 is executed.

[0062] It can be understood that the control circuit can determine the operating state of the target voltage conversion circuit in a number of ways, and can further determine whether the input power (or input current) of the target voltage conversion circuit needs to be controlled. In other words, the control circuit can determine the operating state of the target voltage conversion circuit in a number of ways, and can further determine whether the duty cycle of the switch in the target voltage conversion circuit needs to be adjusted. For example, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the target voltage conversion circuit can be considered to be in an operating state in which the input power needs to be reduced (or, in other words, the switch in the target voltage conversion circuit is operating in a harsh environment and will be damaged at a high risk if it continues to operate). In this case, the control circuit needs to reduce the input current and / or input power of the target voltage conversion circuit. Here, when the operating temperature of the switch in the target voltage conversion circuit is different, the input current that the switch can withstand may be different even if the voltage difference borne by the switch is the same.

[0063] S803: Input voltage and balance of the target voltage conversion circuit S and adjusting a current threshold of the target voltage conversion circuit to a first current threshold based on the voltage.

[0064] Here, when the operating temperature of the switch in the target voltage conversion circuit is high (for example, the temperature of the target voltage conversion circuit is equal to or higher than a temperature threshold), the control circuit reduces the voltage difference borne by the switch in the target voltage conversion circuit (for example, the input voltage and S The maximum input current (e.g., a first current threshold) that the switch in the target voltage conversion circuit can withstand may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., based on the corresponding nominal current when various models of switches bear different voltage differences), or based on a current threshold acquired by the photovoltaic power inverter in a manner such as acquisition, collection, reception, detection, or storage. For example, the photovoltaic power inverter or an external central control system may calculate a curve of a corresponding current threshold when the switch bears different voltage differences at a specific operating temperature or a specific operating temperature range (e.g., a first operating temperature range equal to or greater than the temperature threshold) in the operation process (or design process) of the voltage conversion circuit. Also, the control circuit may obtain the first current threshold based on the curve. The first current threshold may be specifically set based on an application scenario. It may be understood that the first current threshold here may be one current, multiple discrete currents, or a current range including multiple discrete currents or continuous currents.

[0065] In this application, when the operating temperature of the switch in the target voltage conversion circuit is high (e.g., the temperature of the target voltage conversion circuit is equal to or higher than a temperature threshold), if the input current of the switch in the target voltage conversion circuit is equal to or higher than a first current threshold, it indicates that the target voltage conversion circuit is in an operating state in which the target voltage conversion circuit needs to be adjusted, and the control circuit may reduce the duty cycle of the switch in the target voltage conversion circuit to further reduce the input power of the target voltage conversion circuit, thereby avoiding the elements in the target voltage conversion circuit from being damaged by overheating and improving the safety of the target voltage conversion circuit. Also, the control circuit does not completely cut off the input electric energy of the target voltage conversion circuit. This ensures the efficiency of electric energy transmission on the basis of ensuring safety.

[0066] S804: Input voltage and balance of the target voltage conversion circuit S and adjusting a current threshold of the target voltage conversion circuit to a second current threshold based on the voltage.

[0067] Here, when the operating temperature of the switch in the target voltage conversion circuit is low (for example, the temperature of the target voltage conversion circuit is lower than a temperature threshold), the control circuit reduces the voltage difference borne by the switch in the target voltage conversion circuit (for example, the input voltage and SThe second current threshold may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., the difference between the first and second voltage thresholds). Here, the second current threshold is smaller than the first voltage threshold. The value of the second current threshold may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., the corresponding nominal current when various models of switches bear different voltage differences), or may be determined based on the current threshold obtained by the photovoltaic power inverter in a manner such as acquisition, collection, reception, detection, or storage. For example, the photovoltaic power inverter or an external central control system may calculate a corresponding current threshold curve when the switch bears different voltage differences at a specific operating temperature or a specific operating temperature range (e.g., a second operating temperature range lower than the temperature threshold) in the operation process (or design process) of the voltage conversion circuit. Also, the control circuit may obtain the second current threshold based on the curve. The second current threshold may be specifically set based on the application scenario. It can be appreciated that the second current threshold herein can be a single current, a number of discrete currents, or a range of currents including a number of discrete currents or a continuous current.

[0068] In this application, when the operating temperature of the switch in the target voltage conversion circuit is low (e.g., the temperature of the target voltage conversion circuit is below the temperature threshold), if the input current of the switch in the target voltage conversion circuit is equal to or greater than the second current threshold, it indicates that the target voltage conversion circuit is in an operating state in which the target voltage conversion circuit needs to be adjusted, and the control circuit may reduce the duty cycle of the switch in the target voltage conversion circuit to further reduce the input power of the target voltage conversion circuit, thereby avoiding the elements in the target voltage conversion circuit from being damaged by overheating and improving the safety of the target voltage conversion circuit. Also, the control circuit does not completely cut off the input electric energy of the target voltage conversion circuit. This ensures the efficiency of electric energy transmission on the basis of ensuring safety.

[0069] S805: When the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, adjust the duty cycle of the switch in the target voltage conversion circuit to turn on or off the switch in the target voltage conversion circuit so as to reduce the current or input power of the target voltage conversion circuit. control do.

[0070] In some possible implementations, when an input current of the target voltage conversion circuit is equal to or greater than a current threshold of the target voltage conversion circuit, a switching modulation signal is generated based on the input current of the target voltage conversion circuit and the current threshold of the target voltage conversion circuit, and a duty cycle of a switch in the target voltage conversion circuit is controlled based on the switching modulation signal to turn on or off the switch in the target voltage conversion circuit. control do.

[0071] Here, a control circuit (e.g., a current regulation loop (e.g., a proportional regulation circuit or a proportional-integral regulation circuit) and a drive control circuit, or other circuit having a current regulation function and a drive control function) generates a switching modulation signal based on the input current of the target voltage conversion circuit and the current threshold of the target voltage conversion circuit to control the duty cycle of the switch in the target voltage conversion circuit. adjustment For example, the control circuit may be configured to generate a switching modulation signal PWM Alternatively, the driving pulse signal can be generated as a switching modulation signal based on a PWM wave, where the switching modulation signal determines the duty cycle of a switch in the target voltage conversion circuit. adjustment and may further control the input current and / or input power of the target voltage conversion circuit. For example, the control circuit may reduce the duty cycle of a switch in the target voltage conversion circuit to reduce the input current of the target voltage conversion circuit and reduce the input power of the target voltage conversion circuit. It may be understood that the control circuit provided in this application may include a switching modulation signal, DPWM A wave may be used, and another PWM wave (e.g., SWMwave, THIPWM Waves, or CBPWM The switching modulation signal can be a driving pulse signal generated based on these PWM waves. It has a wide range of application and good control effect.

[0072] In some possible implementations, the input voltage and balance of the target voltage conversion circuit S After the step S702, S803, or S804 of adjusting the current threshold of the target voltage conversion circuit based on the voltage is performed, the method further includes: The duty cycle of the switch in the target voltage conversion circuit is adjusted to turn on or off the switch in the target voltage conversion circuit so that the input power of the target voltage conversion circuit remains at the maximum target input power when the input current of the target voltage conversion circuit is less than a current threshold of the target voltage conversion circuit. control This may include.

[0073] Here, when the input current of the target voltage conversion circuit is less than a current threshold (e.g., a third current threshold) of the target voltage conversion circuit, the target voltage conversion circuit may be considered to be in an operating state in which the input power does not need to be reduced (in other words, the switch in the target voltage conversion circuit is operating in a safe environment with a low risk of damage). In this case, the control circuit may adjust the duty cycle of the switch in the target voltage conversion circuit so that the input power of the target voltage conversion circuit remains at the maximum target input power (e.g., the photovoltaic panel connected to the target voltage conversion circuit operates at the maximum power point). Here, the value of the third current threshold may be determined based on the maximum input current of the switch in the target voltage conversion circuit (e.g., based on the corresponding nominal current when various models of switches bear different voltage differences), or may be determined based on a current threshold obtained by the photovoltaic inverter in a manner such as acquisition, collection, reception, detection, or storage. For example, the photovoltaic power inverter or an external central control system may calculate a corresponding current threshold curve when the switch bears different voltage differences at a specific operating temperature or a specific operating temperature range (e.g., a first operating temperature range equal to or greater than a temperature threshold, or a second operating temperature range equal to or less than a temperature threshold) during the operation (or design) of the voltage conversion circuit. The control circuit may obtain a third current threshold based on the curve. The third current threshold may be specifically set based on an application scenario. It may be understood that the third current threshold here may be one current, multiple discrete currents, or a current range including multiple discrete currents or continuous currents. For example, in a first operating temperature range equal to or greater than a temperature threshold, the third current threshold may be equal to or less than the first current threshold. In another example, in a second operating temperature range equal to or less than a temperature threshold, the third current threshold may be equal to or less than the second current threshold. When the third voltage threshold is smaller than the first current threshold (or the second current threshold), the solar power inverter can avoid repeatedly decreasing or increasing the input power of the target voltage conversion circuit via the control circuit when the input current of the target voltage conversion circuit is not stably smaller than the first current threshold (or the second current threshold).In other words, when the third voltage threshold is less than the first current threshold (or the second current threshold), after the input current of the target voltage conversion circuit is stable (e.g., stable and less than the third current threshold), the target voltage conversion circuit of the solar power inverter may be in an operating state where the input power does not need to be reduced (or, in other words, the switches in the target voltage conversion circuit are operating in a safe environment with low risk of damage). In this case, the control circuit may adjust the duty cycle of the switches in the target voltage conversion circuit so that the input power of the target voltage conversion circuit remains at the maximum target input power (e.g., the solar panel connected to the target voltage conversion circuit operates at the maximum power point). This improves power supply efficiency.

[0074] In some possible implementations, the input voltage of the target voltage conversion circuit, the input current of the target voltage conversion circuit, and S After the voltage is detected, the method further comprises: B S Adjusting the duty cycle of a switch in the inverter circuit to turn on or off a switch in the inverter circuit so as to reduce the output power of the inverter circuit when the voltage is equal to or greater than the bus voltage threshold. control This may include.

[0075] It can be appreciated that the control circuit can determine the operating state of the solar power inverter in a number of ways, and can further determine whether the output power (or output current) of the solar power inverter (e.g., inverter circuit) needs to be controlled. SWhen the voltage is equal to or greater than the bus voltage threshold, the inverter circuit may be considered to be in an operating condition that requires a reduced output power (or, in other words, the elements in the photovoltaic inverter are operating in a harsh environment and are at high risk of being damaged if they continue to operate). In this case, the control circuitry needs to reduce the output current and / or output power of the inverter circuit. It may be understood that the bus voltage threshold here may be a voltage, a number of discrete voltages, or a voltage range that includes a number of discrete or continuous voltages.

[0076] It can be understood that S When the voltage is high (e.g., the bus voltage is equal to or greater than the bus voltage threshold), it indicates that the photovoltaic inverter is in an operating state that requires the output power to be reduced. The control circuit can reduce the duty cycle of each switch in the inverter circuit to further reduce the output power of the inverter circuit, to prevent elements in the photovoltaic inverter from being damaged by overheating, and further improve the safety of the power supply.

[0077] In this application, when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, the photovoltaic inverter can adjust the duty cycle of the switch through the control circuit to reduce the input power of the voltage conversion circuit, thereby improving the stability and power supply efficiency of the photovoltaic inverter while ensuring the safety of the power supply. The structure is simple, the method is straightforward and has high applicability.

[0078] The above description is merely a specific implementation of the present invention, and is not intended to limit the scope of protection of the present invention. Any modifications or replacements that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention shall fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A photovoltaic power generation inverter, the photovoltaic power generation inverter including an inverter circuit, a plurality of voltage conversion circuits, a plurality of acquisition circuits, and a control circuit, each voltage conversion circuit including at least one switch; one end of each voltage conversion circuit is configured to be connected to each of a plurality of groups of photovoltaic panels, and the other end of each voltage conversion circuit is configured to be connected in parallel to a bus and then connected to a load via the inverter circuit; the plurality of acquisition circuits are connected to the control circuit and configured to detect voltages or currents of the plurality of voltage conversion circuits and the bus; and the control circuit is connected to the switch in each voltage conversion circuit; The plurality of acquisition circuits are configured to detect an input voltage of a target voltage conversion circuit and the voltage of the bus, and the target voltage conversion circuit is any one or more of the plurality of voltage conversion circuits; the control circuit is configured to adjust a current threshold of the target voltage conversion circuit based on the input voltage of the target voltage conversion circuit and the voltage of the bus; the control circuit is configured to adjust a duty cycle of the switch in the target voltage conversion circuit to adjust a turn-on or turn-off of the switch in the target voltage conversion circuit so as to reduce a current or an input power of the target voltage conversion circuit when an input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit; Photovoltaic inverter.

2. The plurality of acquisition circuits are further configured to detect a temperature of the target voltage conversion circuit; the control circuit is further configured to adjust the current threshold of the target voltage conversion circuit to a first current threshold based on the input voltage of the target voltage conversion circuit and the voltage of the bus when the temperature of the target voltage conversion circuit is equal to or greater than a temperature threshold.

2. The photovoltaic inverter of claim 1.

3. 3. The solar power inverter of claim 2, wherein the control circuit is further configured to adjust the current threshold of the target voltage conversion circuit to a second current threshold based on the input voltage of the target voltage conversion circuit and the voltage of the bus when the temperature of the target voltage conversion circuit is less than the temperature threshold, the second current threshold being greater than or equal to the first current threshold.

4. 4. The solar power generation inverter according to claim 1, wherein the control circuit is further configured to generate a switching modulation signal based on the input current of the target voltage conversion circuit and the current threshold of the target voltage conversion circuit when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, and to control turn-on or turn-off of the switch in the target voltage conversion circuit based on the switching modulation signal to adjust the duty cycle of the switch in the target voltage conversion circuit.

5. 5. The solar power inverter of claim 1, wherein the control circuit is further configured to adjust the turn-on or turn-off of the switches in the target voltage conversion circuit to adjust the duty cycle of the switches in the target voltage conversion circuit so that the input power of the target voltage conversion circuit remains at a maximum target input power when the input current of the target voltage conversion circuit is less than the current threshold of the target voltage conversion circuit.

6. 6. The photovoltaic inverter of claim 1, wherein the inverter circuit comprises a switch, and the control circuit is further configured to adjust a duty cycle of the switch in the inverter circuit to adjust a turn-on or turn-off of the switch in the inverter circuit to reduce an output power of the inverter circuit when the voltage on the bus is equal to or greater than a bus voltage threshold.

7. A power control method applicable to a solar power generation system, the solar power generation system having an inverter circuit and a plurality of voltage conversion circuits, One end of each voltage conversion circuit is configured to be connected to a photovoltaic power generation panel, and the other end of each voltage conversion circuit is configured to be connected in parallel to a bus and then connected to a load via the inverter circuit, and the method includes: An input voltage of a target voltage conversion circuit, an input current of the target voltage conversion circuit, and a voltage of the bus are detected, the target voltage conversion circuit being at least one of the plurality of voltage conversion circuits; adjusting a current threshold of the target voltage translation circuit based on the input voltage of the target voltage translation circuit and the voltage of the bus; adjusting a duty cycle of a switch in the target voltage conversion circuit to adjust a turn-on or turn-off of the switch in the target voltage conversion circuit so as to reduce a current or an input power of the target voltage conversion circuit when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit; The control method includes:

8. adjusting a current threshold of the target voltage conversion circuit based on the input voltage of the target voltage conversion circuit and the voltage of the bus, Detecting a temperature of the target voltage conversion circuit; adjusting the current threshold of the target voltage conversion circuit to a first current threshold based on the input voltage of the target voltage conversion circuit and the voltage of the bus when the temperature of the target voltage conversion circuit is equal to or greater than a temperature threshold; The method of claim 7, comprising:

9. After detecting the temperature of the target voltage conversion circuit, the method further comprises: adjusting the current threshold of the target voltage conversion circuit to a second current threshold based on the input voltage of the target voltage conversion circuit and the voltage of the bus when the temperature of the target voltage conversion circuit is less than the temperature threshold, the second current threshold being greater than or equal to the first current threshold; The method of claim 8, comprising:

10. After adjusting a current threshold of the target voltage translation circuit based on the input voltage of the target voltage translation circuit and the voltage of the bus, the method further comprises: generating a switching modulation signal based on the input current of the target voltage conversion circuit and the current threshold of the target voltage conversion circuit when the input current of the target voltage conversion circuit is equal to or greater than the current threshold of the target voltage conversion circuit, and controlling the duty cycle of the switch in the target voltage conversion circuit based on the switching modulation signal to adjust the turn-on or turn-off of the switch in the target voltage conversion circuit; 10. The method of claim 7, further comprising:

11. After adjusting a current threshold of the target voltage translation circuit based on the input voltage of the target voltage translation circuit and the voltage of the bus, the method further comprises: adjusting the duty cycle of the switch in the target voltage conversion circuit to adjust the turn-on or turn-off of the switch in the target voltage conversion circuit so that the input power of the target voltage conversion circuit remains at a maximum target input power when the input current of the target voltage conversion circuit is less than the current threshold of the target voltage conversion circuit.

11. The method of claim 7, further comprising:

12. The inverter circuit has a switch, and after detecting an input voltage of a target voltage conversion circuit, an input current of the target voltage conversion circuit, and a voltage of the bus, the method further comprises: adjusting a duty cycle of the switch in the inverter circuit to adjust the turn-on or turn-off of the switch in the inverter circuit to reduce an output power of the inverter circuit when the voltage of the bus is equal to or greater than a bus voltage threshold; 12. The method of claim 7, further comprising:

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