Optimizer, optimizer control method and photovoltaic power generation system

Abstract

The embodiment of the invention discloses an optimizer, a control method of the optimizer and a photovoltaic power generation system, relates to the technical field of energy, and solves the problem that a passive surge protection device cannot indicate whether surge ends or not so that the optimizer and an inverter can perform protection adjustment. And a controller in the optimizer is used for controlling the DCDC power conversion circuit to stop power conversion and controlling the surge protection circuit to discharge energy at the output end of the DCDC power conversion circuit under the condition that the voltage at the output end of the DCDC power conversion circuit is greater than or equal to a surge voltage threshold. After the surge protection circuit is controlled to discharge the energy of the output end of the DCDC power conversion circuit, under the condition that the voltage of the output end of the DCDC power conversion circuit is equal to a surge ending voltage threshold value, the surge protection circuit is controlled to stop discharging the energy of the output end of the DCDC power conversion circuit, and the DCDC power conversion circuit is controlled to carry out power conversion.

Description

Technical Field

[0001] The present application relates to the field of energy technology, and in particular to an optimizer, a control method for the optimizer, and a photovoltaic power generation system. Background Art

[0002] The photovoltaic power generation system includes an optimizer and an inverter. The input end of the optimizer is used to connect to the photovoltaic array, and the output end of the optimizer is used to connect to the input end of the inverter. Alternatively, the output end of the optimizer is used to connect to the input end of the inverter after being connected in series with the output ends of other optimizers, and the output end of the inverter is used to connect to the power grid or load. The photovoltaic array is used to convert solar energy into direct current, the optimizer is used to perform power conversion on the direct current, and the inverter is used to convert the power-converted direct current into alternating current and transmit it to the power grid or load.

[0003] By providing a passive surge protection device, such as a transient voltage suppressor (TVS), at the output end of the optimizer, other devices in the optimizer can be protected when a surge occurs at the output end of the optimizer.

[0004] However, when using passive surge protection devices for surge protection, the optimizer and inverter will not be actively shut down, but will passively withstand the impact of the surge. If the protection capability of the passive surge protection device is insufficient, the optimizer and inverter will be damaged. Therefore, the design requirements for passive surge protection devices are high, which will lead to higher optimizer costs. Secondly, passive surge protection devices cannot indicate whether the surge has ended so that the optimizer and inverter can perform protection adjustments. At the same time, the possibility of failure of passive surge protection devices is also high, which will lead to lower reliability of the optimizer and inverter. In summary, when using passive surge protection devices for surge protection, the cost of photovoltaic power generation systems will be higher and the reliability will be lower. Summary of the invention

[0005] The embodiments of the present application provide an optimizer, an optimizer control method, and a photovoltaic power generation system, which solve the problem that a passive surge protection device cannot indicate whether a surge has ended so as to provide protection and adjustment for the optimizer and inverter.

[0006] In order to achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0007] In a first aspect of an embodiment of the present application, an optimizer is provided, which includes a DCDC power conversion circuit, a surge protection circuit, an auxiliary power supply and a controller. The input end of the DCDC power conversion circuit is used to connect to a photovoltaic array, the output end of the DCDC power conversion circuit and the first end of the surge protection circuit are used to connect to an inverter, and the second end of the surge protection circuit is connected to the output end of the auxiliary power supply, and the auxiliary power supply is used to power the surge protection circuit. The controller is used to control the DCDC power conversion circuit to stop power conversion of the direct current output of the photovoltaic array when the voltage at the output end of the DCDC power conversion circuit is greater than or equal to the surge voltage threshold, and control the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit. The controller is also used to control the surge protection circuit to stop discharging the energy at the output end of the DCDC power conversion circuit when the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold after controlling the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit, and control the DCDC power conversion circuit to perform power conversion on the direct current output of the photovoltaic array, and the surge end voltage threshold is less than the surge voltage threshold.

[0008] Based on this solution, when the voltage at the output end of the DCDC power conversion circuit is greater than or equal to the surge voltage threshold and a surge occurs at the output end of the DCDC power conversion circuit, the controller controls the DCDC power conversion circuit to stop power conversion of the DC power output of the photovoltaic array, and controls the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit, so that the optimizer can be surge protected to avoid damage to the components in the optimizer. After the controller controls the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit, the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold, and the voltage at the output end of the DCDC power conversion circuit indicates that the surge at the output end of the DCDC power conversion circuit is over, the controller controls the surge protection circuit to stop discharging the energy at the output end of the DCDC power conversion circuit, and controls the DCDC power conversion circuit to power conversion of the DC power output of the photovoltaic array, so that the controller can timely control the DCDC power conversion circuit in the optimizer to resume working state. It can be understood that the voltage at the output end of the DCDC power conversion circuit can indicate whether the surge is over, so that the optimizer and inverter can perform protection and adjustment, thereby improving the reliability of the photovoltaic power generation system. At the same time, there is no need to use multiple levels of high-specification passive surge protection devices with a higher probability of failure, which can reduce the cost of the photovoltaic power generation system.

[0009] In combination with the first aspect, in a possible implementation, the surge protection circuit includes a first resistor, a switch tube, a second resistor, and a voltage regulating circuit. One end of the first resistor is connected to the first end of the surge protection circuit, the other end of the first resistor is connected to the first end of the switch tube, the second end of the switch tube is connected to the first end of the voltage regulating circuit, the second end of the voltage regulating circuit is connected to the second end of the surge protection circuit, the control end of the switch tube is connected to one end of the second resistor, the other end of the second resistor is connected to the controller, and the voltage regulating circuit is used to adjust the voltage output by the auxiliary power supply so that the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold.

[0010] Based on this solution, the surge protection circuit implements surge protection through the first resistor and the switch tube, and does not need to use multi-level high-specification passive surge protection devices to implement surge protection, which can avoid the high cost of the optimizer. When surges occur multiple times, the possibility of failure of the first resistor and the switch tube is lower than the possibility of failure of the passive surge protection device, thereby improving the reliability of the optimizer.

[0011] In combination with the first aspect, in a possible implementation manner, the voltage regulation circuit includes a voltage dividing resistor, a low voltage dropout linear regulator, or a BUCK circuit.

[0012] In combination with the first aspect, in a possible implementation, the optimizer further includes a pass-through circuit connected in parallel with the DCDC power conversion circuit. The controller is also used to control the pass-through circuit to be in an off state when the voltage at the output end of the DCDC power conversion circuit is greater than or equal to the surge voltage threshold.

[0013] Based on this solution, when the voltage at the output end of the DCDC power conversion circuit is greater than or equal to the surge voltage threshold, the controller controls the through circuit to be in an off state, thereby avoiding damage to components in the through circuit and improving the reliability of the optimizer.

[0014] In combination with the first aspect, in a possible implementation, the controller is also used to control the DCDC power conversion circuit to stop power conversion of the direct current output by the photovoltaic array and control the pass-through circuit to be in a pass-through state when the input current of the DCDC power conversion circuit is greater than or equal to the current threshold and the voltage at the output end of the DCDC power conversion circuit is less than the surge voltage threshold.

[0015] Based on this solution, when the input current of the DCDC power conversion circuit is greater than or equal to the current threshold and the voltage at the output end of the DCDC power conversion circuit is less than the surge voltage threshold, the controller controls the DCDC power conversion circuit to stop power conversion of the DC power output by the photovoltaic array, and controls the pass-through circuit to be in a pass-through state, so that no surge occurs at the output end of the DCDC power conversion circuit, and the DCDC power conversion circuit is not required to perform power conversion on the DC power output by the photovoltaic array. When the output current of the photovoltaic array is reduced, for example, when the photovoltaic array is not blocked, the optimizer can directly transmit the DC power output by the photovoltaic array to the inverter.

[0016] In combination with the first aspect, in a possible implementation method, the controller is also used to control the DCDC power conversion circuit to stop power conversion of the direct current output of the photovoltaic array and control the pass-through circuit to be in a pass-through state when the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold and the input current of the DCDC power conversion circuit is greater than or equal to the current threshold after controlling the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit.

[0017] Based on this solution, after the controller controls the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit, when the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold and the input current of the DCDC power conversion circuit is greater than or equal to the current threshold, the controller controls the DCDC power conversion circuit to stop power conversion of the DC power output by the photovoltaic array, and controls the pass-through circuit to be in a pass-through state, so that after the surge at the output end of the DCDC power conversion circuit ends, the controller can promptly control the pass-through circuit in the optimizer to resume the working state, and when the DCDC power conversion circuit is not required to perform power conversion on the DC power output by the photovoltaic array and the output current of the photovoltaic array is reduced, for example, when the photovoltaic array is not blocked, the optimizer can directly transmit the DC power output by the photovoltaic array to the inverter.

[0018] In combination with the first aspect, in a possible implementation, the pass-through circuit includes a third resistor, a fourth resistor, a fifth resistor, a positive channel metal oxide semi-conductor field effect transistor PMOS, and a negative channel metal oxide semi-conductor field effect transistor NMOS. One end of the third resistor and the source end of the PMOS are connected to the input end of the pass-through circuit, the drain end of the PMOS is connected to the output end of the pass-through circuit, the gate end of the PMOS is connected to one end of the fourth resistor, the other end of the third resistor and the other end of the fourth resistor are connected to the drain end of the NMOS, the source end of the NMOS is connected to the ground end, the gate end of the NMOS is connected to the first end of the fifth resistor, and the other end of the fifth resistor is connected to the controller.

[0019] Based on this solution, the pass-through circuit includes a third resistor, a fourth resistor, a fifth resistor, a PMOS and an NMOS. Compared with the existing optimizer, which uses a bootstrap capacitor driver IC or a driver IC driven by a built-in charge pump to drive the MOS in the BUCK circuit of the optimizer to be in a continuously on state to achieve a pass-through mode, there is no need to use a bootstrap capacitor driver IC, and thus there is no need to design a transformer in the auxiliary power supply of the optimizer, which can avoid the problems of high complexity, large size, high cost and introduction of noise interference in the optimizer, and there is no need to use a driver IC driven by a built-in charge pump, which can avoid the problem that the driver IC driven by a built-in charge pump needs to be customized and has a high cost.

[0020] In combination with the first aspect, in a possible implementation manner, the DCDC power conversion circuit is used to perform maximum power point tracking (MPPT) on the connected photovoltaic array.

[0021] According to a second aspect of an embodiment of the present application, a control method of an optimizer is provided, which is applied to an optimizer, and the method includes: when the voltage at the output end of the DCDC power conversion circuit is greater than or equal to the surge voltage threshold, the DCDC power conversion circuit is controlled to stop power conversion of the direct current output by the photovoltaic array, and the surge protection circuit is controlled to discharge the energy at the output end of the DCDC power conversion circuit. After the surge protection circuit is controlled to discharge the energy at the output end of the DCDC power conversion circuit, when the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold, the surge protection circuit is controlled to stop discharging the energy at the output end of the DCDC power conversion circuit, and the DCDC power conversion circuit is controlled to perform power conversion on the direct current output by the photovoltaic array, and the surge end voltage threshold is less than the surge voltage threshold. The input end of the DCDC power conversion circuit is used to connect the photovoltaic array, the output end of the DCDC power conversion circuit and the first end of the surge protection circuit are used to connect the inverter, and the second end of the surge protection circuit is connected to the output end of the auxiliary power supply, and the auxiliary power supply is used to power the surge protection circuit.

[0022] In conjunction with the second aspect, in a possible implementation manner, the converter further includes a pass-through circuit connected in parallel with the DCDC power conversion circuit, and the method further includes:

[0023] When the voltage at the output end of the DCDC power conversion circuit is greater than or equal to the surge voltage threshold, the through circuit is controlled to be in an off state.

[0024] In combination with the second aspect, in a possible implementation, the method also includes: when the input current of the DCDC power conversion circuit is greater than or equal to the current threshold and the voltage at the output end of the DCDC power conversion circuit is less than the surge voltage threshold, controlling the DCDC power conversion circuit to stop power conversion of the direct current output by the photovoltaic array, and controlling the pass-through circuit to be in a pass-through state.

[0025] In combination with the second aspect, in a possible implementation, the method also includes: after controlling the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit, when the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold, and the input current of the DCDC power conversion circuit is greater than or equal to the current threshold, controlling the DCDC power conversion circuit to stop power conversion of the direct current output by the photovoltaic array, and controlling the pass-through circuit to be in a pass-through state.

[0026] In a third aspect of an embodiment of the present application, a photovoltaic power generation system is provided, the photovoltaic power generation system includes an optimizer, and an inverter connected to the optimizer, the input end of the optimizer is used to connect to a photovoltaic array, the output end of the inverter is used to connect to a power grid or a load, the optimizer is used to perform power conversion on the direct current output by the photovoltaic array, and the inverter is used to convert the direct current after power conversion into alternating current and transmit it to the power grid or the load; wherein the optimizer includes a DCDC power conversion circuit, a surge protection circuit, an auxiliary power supply and a controller. The input end of the DCDC power conversion circuit is used to connect to the photovoltaic array, the output end of the DCDC power conversion circuit and the first end of the surge protection circuit are used to connect to the inverter, the second end of the surge protection circuit is connected to the output end of the auxiliary power supply, and the auxiliary power supply is used to power the surge protection circuit. The controller is used to control the DCDC power conversion circuit to stop power conversion on the direct current output by the photovoltaic array when the voltage at the output end of the DCDC power conversion circuit is greater than or equal to the surge voltage threshold, and control the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit. The controller is also used to control the surge protection circuit to stop discharging the energy at the output end of the DCDC power conversion circuit after controlling the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit, when the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold, and control the DCDC power conversion circuit to perform power conversion on the direct current output by the photovoltaic array, and the surge end voltage threshold is less than the surge voltage threshold.

[0027] In conjunction with the third aspect, in one possible implementation, the optimizer further includes a pass-through circuit connected in parallel with the DCDC power conversion circuit. The controller is also used to control the pass-through circuit to be in an off state when the voltage at the output end of the DCDC power conversion circuit is greater than or equal to the surge voltage threshold.

[0028] In combination with the third aspect, in one possible implementation, the controller is also used to control the DCDC power conversion circuit to stop power conversion of the DC power output by the photovoltaic array and control the pass-through circuit to be in a pass-through state when the input current of the DCDC power conversion circuit is greater than or equal to the current threshold and the voltage at the output end of the DCDC power conversion circuit is less than the surge voltage threshold.

[0029] In combination with the third aspect, in one possible implementation, the controller is also used to control the DCDC power conversion circuit to stop power conversion of the DC power output by the photovoltaic array and control the pass-through circuit to be in a pass-through state when the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold and the input current of the DCDC power conversion circuit is greater than or equal to the current threshold after controlling the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit.

[0030] The description of the second and third aspects in this application can refer to the detailed description of the first aspect; and the beneficial effects of the second and third aspects can refer to the analysis of the beneficial effects of the first aspect, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of a circuit topology of a photovoltaic power generation system;

[0032] Figure 2 is a schematic diagram of a circuit topology of an optimizer;

[0033] Figure 3 A schematic diagram of a circuit topology of a photovoltaic power generation system provided in an embodiment of the present application;

[0034] Figure 4 A schematic diagram of a circuit topology of an optimizer provided in an embodiment of the present application;

[0035] Figure 5 A schematic diagram of another circuit topology of an optimizer provided in an embodiment of the present application;

[0036] Figure 6 A circuit topology diagram of another optimizer provided in an embodiment of the present application;

[0037] Figure 7 A schematic flow chart of a control method for an optimizer provided in an embodiment of the present application;

[0038] Figure 8 A flowchart of another optimizer control method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] The following will discuss the making and use of each embodiment in detail. However, it should be understood that many applicable inventive concepts provided by this application can be implemented in a variety of specific environments. The specific embodiments discussed are only used to illustrate the specific ways to implement and use this description and this technology, and do not limit the scope of this application.

[0040] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art.

[0041] Various circuits or other components may be described or referred to as being "configured to" perform one or more tasks. In this case, "configured to" is used to imply structure by indicating that the circuit / component includes structure (e.g., circuitry) that performs the one or more tasks during operation. Thus, even when the specified circuit / component is not currently operational (e.g., not turned on), the circuit / component may be referred to as being configured to perform the task. Circuits / components used with the phrase "configured to" include hardware, such as circuits that perform an operation, etc.

[0042] The technical scheme in the embodiment of the present application will be described below in conjunction with the accompanying drawings in the embodiment of the present application. In the present application, "at least one" refers to one or more, and "multiple" refers to two or more. "And / or" describes the association relationship of the associated objects, indicating that there may be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. "At least one of the following" or its similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b or c can represent: a, b, c, a and b, a and c, b and c or a, b and c, where a, b and c can be single or multiple. In addition, in the embodiment of the present application, the words "first", "second" and the like do not limit the quantity and order.

[0043] In this application, the words "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the words "exemplary" or "for example" is intended to present the related concepts in a concrete way.

[0044] Before introducing the embodiments of the present application, the technical terms and background technologies involved in the present application are first introduced.

[0045] Optimizer: Also known as power optimizer or photovoltaic optimizer, it is a component-level device with DC input and DC output. The optimizer is connected in series with the photovoltaic modules and adopts the predicted current and voltage technology to ensure that the photovoltaic modules are always in the optimal working state. It can achieve maximum power point tracking (MPPT) and component-level shutdown capabilities.

[0046] Photovoltaic array: A photovoltaic array includes at least one photovoltaic component. When a photovoltaic array includes multiple photovoltaic components, the multiple photovoltaic components can be connected in series, or connected in parallel, or some of the multiple photovoltaic components can be connected in series and the rest can be connected in parallel.

[0047] Electrical surge: refers to the instantaneous overvoltage abnormal fault phenomenon in the system that exceeds the normal operating voltage.

[0048] In a photovoltaic power generation system including an optimizer and an inverter, the optimizer generally includes a buck conversion circuit (also referred to as a buck circuit), and the inverter includes a boost conversion circuit (also referred to as a boost circuit), and an inverter circuit connected to the boost circuit. The optimizer needs to have a surge protection function, so that when a surge occurs at the output end of the optimizer, the output end of the optimizer can withstand a differential mode voltage of 1500V, which can protect the components in the optimizer and improve the reliability of the optimizer. In addition, the optimizer also needs to have a pass-through mode, so that when the buck circuit in the optimizer is not required to perform power conversion on the direct current output by the photovoltaic module, for example, when the photovoltaic module is not blocked and the buck circuit is not required to adjust the output current of the photovoltaic module, the optimizer can directly transmit the direct current output by the photovoltaic module to the inverter.

[0049] like Figure 1 The schematic diagram of the circuit topology of a photovoltaic power generation system 100 is shown. The photovoltaic power generation system 100 includes an optimizer 110 and an inverter 120 connected to the optimizer 110. The optimizer 110 includes a BUCK circuit 111, a first transient voltage suppressor TVS1, a second transient voltage suppressor TVS2, and a third transient voltage suppressor TVS3. The input end of the BUCK circuit 111 is used to connect to the photovoltaic array 200, the first transient voltage suppressor TVS1 and the second transient voltage suppressor TVS2 are connected in parallel, and the first transient voltage suppressor TVS1, the second transient voltage suppressor TVS2 and the third transient voltage suppressor TVS3 connected in parallel are connected in series between the two output ends of the BUCK circuit 111, and the output end of the BUCK circuit 111 is used to connect to the input end of the inverter 120, and the output end of the inverter 120 is used to connect to the power grid or the load 300.

[0050] When a surge occurs at the output of the optimizer 110, the voltage at the output of the BUCK circuit 111 will exceed the normal operating voltage, which may damage the components in the BUCK circuit 111. The surge energy at the output of the BUCK circuit 111 is absorbed by the first transient voltage suppressor TVS1, the second transient voltage suppressor TVS2, and the third transient voltage suppressor TVS3, thereby protecting the components in the BUCK circuit 111. When the surge ends, the first transient voltage suppressor TVS1, the second transient voltage suppressor TVS2, and the third transient voltage suppressor TVS3 no longer work, which is equivalent to a circuit breaker.

[0051] However, the passive surge protection devices (the first transient voltage suppressor TVS1, the second transient voltage suppressor TVS2, and the third transient voltage suppressor TVS3) cannot indicate the end of the surge for the optimizer 110 and the inverter 120 to perform protection and adjustment. In the case of the end of the surge, the optimizer 110 and the inverter 120 cannot resume working in time, which will result in low efficiency of the photovoltaic power generation system 100. In the case that the surge has not ended, if the optimizer 110 and the inverter 120 resume working, it may cause device damage, which will result in low reliability of the photovoltaic power generation system 100. Secondly, when surge protection is performed by passive surge protection devices, the optimizer 110 and the inverter 120 will not be actively shut down, but will passively withstand the impact of the surge. The surge energy absorption and protection effect are completely dependent on the performance of the passive protection device. Therefore, it is necessary to use multi-level high-specification passive surge protection devices to achieve surge protection, which will result in a higher cost for the optimizer 110. Finally, when surges occur multiple times, the passive surge protection device is more likely to fail, resulting in lower reliability of the optimizer 110. In summary, when passive surge protection devices are used for surge protection, the photovoltaic power generation system 100 will have higher costs and lower reliability.

[0052] Reference Figure 1 The BUCK circuit 111 includes a first metal-oxide-semiconductor field-effect transistor (MOSFET) MOS1, a second metal-oxide-semiconductor field-effect transistor MOS2 and an inductor L. The first metal-oxide-semiconductor field-effect transistor MOS1 and the inductor L are connected in series between an input terminal and an output terminal of the BUCK circuit 111, and the second metal-oxide-semiconductor field-effect transistor MOS2 is arranged between a connection point between the first metal-oxide-semiconductor field-effect transistor MOS1 and the inductor L and another input terminal of the BUCK circuit 111.

[0053] Continue to refer to Figure 1By controlling the first metal oxide semiconductor field effect transistor MOS1 in the BUCK circuit 111 to be in a continuously conducting state, the optimizer 110 can realize the direct mode, and the optimizer 110 can directly transmit the DC power output by the photovoltaic array 200 to the inverter 120. Since the first metal oxide semiconductor field effect transistor MOS1 is not connected to the ground through a wire and is in a floating state, in order to control the first metal oxide semiconductor field effect transistor MOS1 to be continuously conducting, the following two solutions are generally adopted:

[0054] In the first solution, a bootstrap capacitor driver integrated circuit (IC) can be used to drive the first metal oxide semiconductor field effect transistor MOS1 to be in a continuous on state. However, the bootstrap capacitor driver IC needs to charge the bootstrap capacitor in the bootstrap capacitor driver IC through the second metal oxide semiconductor field effect transistor MOS2 being in a continuous on state, so as to drive the first metal oxide semiconductor field effect transistor MOS1 to be in a continuous on state. At this time, the two input terminals of the BUCK circuit 111 are short-circuited, and the solution cannot be implemented.

[0055] To solve this problem, Figure 2 As shown in (a), an isolated flyback converter (also referred to as Flyback) can be designed in the auxiliary power supply 112 of the optimizer 110, and the Flyback can couple an isolated power supply to charge the bootstrap capacitor in the bootstrap capacitor driver IC, so that the bootstrap driver IC can drive the first metal oxide semiconductor field effect transistor MOS1 to be in a continuous conduction state. Specifically, the auxiliary power supply 112 may include a first inductor L1, a second inductor L2, a diode D and a capacitor C, the first inductor L1 is arranged between the input end and the output end of the auxiliary power supply 112, the second inductor L2 and the first inductor L1 are magnetically coupled to form a transformer, one end of the second inductor L2 is connected to the positive electrode of the diode D, the capacitor C is arranged between the other end of the second inductor L2 and the negative electrode of the diode D, and the two ends of the capacitor C are used to connect the bootstrap driver IC to charge the bootstrap capacitor in the bootstrap driver IC, so that the bootstrap driver IC can drive the first metal oxide semiconductor field effect transistor MOS1 to be in a continuous conduction state.

[0056] Or, if Figure 2As shown in (b), an isolated buck converter (also called Flybuck) can be designed in the auxiliary power supply 112 of the optimizer 110. The Flybuck can couple an isolated power supply to charge the bootstrap capacitor in the bootstrap capacitor driver IC, so that the bootstrap driver IC can drive the first metal oxide semiconductor field effect transistor MOS1 to be in a continuously turned-on state. Specifically, the auxiliary power supply 112 may include a first inductor L1, a second inductor L2, a diode D, a capacitor C, a first resistor R1 and a second resistor R2. The first inductor L1 is arranged between the input end and the output end of the auxiliary power supply 112. The second inductor L2 is magnetically coupled with the first inductor L1 to form a transformer. One end of the second inductor L2 is connected to the positive electrode of the diode D. The capacitor C and the first resistor R1 are connected in parallel, and the parallel-connected capacitor C and the first resistor R1 are arranged between the other end of the second inductor L2 and the negative electrode of the diode D. One end of the second resistor R2 is connected to the negative electrode of the diode D. The other end of the second resistor R2 is used to connect to a bootstrap driver IC to charge the bootstrap capacitor in the bootstrap driver IC, so that the bootstrap driver IC can drive the first metal oxide semiconductor field effect transistor MOS1 to be in a continuously on state.

[0057] However, when designing Flyback or Flybuck in the auxiliary power supply 112 of the optimizer 110, a transformer needs to be designed, which increases the volume of the magnetic device, which will lead to higher complexity, larger volume, higher cost of the optimizer 110, and will introduce noise interference.

[0058] In the second solution, a driver IC with a built-in charge pump driver may be used. The driver IC may charge the bootstrap capacitor through an internal integrated MOS, so that the driver IC may drive the first metal oxide semiconductor field effect transistor MOS1 to be in a continuously turned-on state.

[0059] However, there are few options for driver ICs with built-in charge pump drivers, and customization is required and the cost is relatively high, which will result in a higher cost for the optimizer 110 .

[0060] In summary, when surge protection is currently performed on the optimizer, there is a problem that the passive surge protection device cannot indicate whether the surge has ended, so that the optimizer and inverter can perform protection and adjustment. In addition, when implementing the direct-through mode of the optimizer, there are problems such as high complexity, large volume, high cost, and the introduction of noise interference. Based on this, an embodiment of the present application provides an optimizer, and after the controller controls the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit, when the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold, the voltage at the output end of the DCDC power conversion circuit indicates that the surge at the output end of the DCDC power conversion circuit has ended, and the direct-through mode is realized by adding a direct-through circuit, and there is no need to use a driver IC, thereby reducing the complexity of the optimizer, reducing the volume and reducing the cost.

[0061] The optimizer provided in the embodiment of the present application can be applied to a photovoltaic power generation system, such as Figure 3 FIG. 4 is a schematic diagram of a circuit topology of a photovoltaic power generation system 400 provided in an embodiment of the present application. The photovoltaic power generation system 400 includes optimizers 411 to 41m and an inverter 420, where m is a positive integer. Figure 3 Each optimizer can be used to connect to a photovoltaic array, for example, optimizer 411 is used to connect to photovoltaic array 511, and optimizer 41m is used to connect to photovoltaic array 51n, where n is a positive integer. The output ends of the m optimizers from optimizer 411 to optimizer 41m are connected in series and then connected to the input end of inverter 420, and the output end of inverter 420 is used to connect to the power grid or load 300.

[0062] Photovoltaic arrays 511 to 51n are used to convert solar energy into direct current. After power conversion by correspondingly connected optimizers 411 to 41m, the direct current output by the m optimizers is connected in series to the input end of the inverter 420. The inverter 420 is used to convert direct current into alternating current and transmit it to the power grid or load 300.

[0063] In a possible embodiment, the surge protection solution and the solution for implementing the pass-through mode provided in the embodiment of the present application can also be applied to communication power supply, vehicle power supply or site power supply, etc., in devices or systems that require surge protection and implementation of the pass-through mode, and the embodiment of the present application is not limited to this.

[0064] like Figure 4As shown, it is a schematic diagram of a circuit topology of an optimizer 600 provided in an embodiment of the present application. The circuit topology of the optimizer 600 can be the circuit topology of any optimizer among the above-mentioned optimizers 411 to 41m, and the optimizer 600 includes a direct current to direct current (DCDC) power conversion circuit 610, a surge protection circuit 620, an auxiliary power supply 630 and a controller 640. The input end of the DCDC power conversion circuit 610 is used to connect to the photovoltaic array 200, the output end of the DCDC power conversion circuit 610 and the first end of the surge protection circuit 620 are used to connect to the inverter 420, the second end of the surge protection circuit 620 is connected to the output end of the auxiliary power supply 630, and the auxiliary power supply 630 is used to power the surge protection circuit 620.

[0065] The controller 640 is used to control the DCDC power conversion circuit 610 to stop power conversion of the DC power output by the photovoltaic array 200 when the voltage at the output end of the DCDC power conversion circuit 610 is greater than or equal to the surge voltage threshold, and control the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610. The embodiment of the present application does not limit the specific value of the surge voltage threshold. Thus, surge protection can be achieved to avoid damage to the components in the DCDC power conversion circuit 610.

[0066] The controller 640 is also used to control the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, and the voltage at the output end of the DCDC power conversion circuit 610 is equal to the surge end voltage threshold. When the voltage at the output end of the DCDC power conversion circuit 610 indicates that the surge at the output end of the DCDC power conversion circuit is over, control the surge protection circuit 620 to stop discharging the energy at the output end of the DCDC power conversion circuit 610, and control the DCDC power conversion circuit 610 to perform power conversion on the direct current output by the photovoltaic array 200. The surge end voltage threshold is less than the surge voltage threshold. The embodiment of the present application does not limit the specific value of the surge end voltage threshold.

[0067] Compared with the above-mentioned optimizer 110 that uses passive surge protection devices for surge protection, in the optimizer 600 provided in the embodiment of the present application, after the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, the voltage at the output end of the DCDC power conversion circuit 610 is equal to the surge end voltage threshold. When the voltage at the output end of the DCDC power conversion circuit 610 indicates that the surge at the output end of the DCDC power conversion circuit 610 is over, the surge protection circuit 620 is controlled to stop discharging the energy at the output end of the DCDC power conversion circuit 610, and the DCDC power conversion circuit 610 is controlled to perform power conversion on the direct current output by the photovoltaic array 200, so that the controller 640 can timely control the DCDC power conversion circuit 610 in the optimizer 600 to resume the working state, thereby avoiding the low efficiency of the photovoltaic power generation system 400. The inverter 420 can restore the working state in time after the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, and the voltage at the output end of the DCDC power conversion circuit 610 is equal to the surge end voltage threshold, indicating that the surge at the output end of the DCDC power conversion circuit 610 has ended, thereby avoiding the low efficiency of the photovoltaic power generation system 400. After the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, when the voltage at the output end of the DCDC power conversion circuit 610 is not equal to the surge end voltage threshold, the DCDC power conversion circuit 610 in the optimizer 600 is not controlled to restore the working state. The inverter 420 can not restore the working state after the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, when the voltage at the output end of the DCDC power conversion circuit 610 is not equal to the surge end voltage threshold, thereby avoiding device damage and improving the reliability of the photovoltaic power generation system 400.

[0068] In a possible embodiment, Figure 5As shown, the surge protection circuit 620 includes a first resistor R1, a switch tube Q, a second resistor R2 and a voltage regulating circuit 621. One end of the first resistor R1 is connected to the first end of the surge protection circuit 620, the other end of the first resistor R1 is connected to the first end of the switch tube Q, the second end of the switch tube Q is connected to the first end of the voltage regulating circuit 621, the second end of the voltage regulating circuit 621 is connected to the second end of the surge protection circuit 620, the control end of the switch tube Q is connected to one end of the second resistor R2, and the other end of the second resistor R2 is connected to the controller 640. The voltage regulating circuit 621 is used to adjust the voltage output by the auxiliary power supply 630 so that the voltage at the output end of the DCDC power conversion circuit 610 is equal to the surge end voltage threshold. The controller 640 is specifically used to control the switch tube Q to turn on when the voltage at the output end of the DCDC power conversion circuit 610 is greater than or equal to the surge voltage threshold, and absorb surge energy through the first resistor R1 and the switch tube Q in the surge protection circuit 620 to discharge the voltage at the output end of the DCDC power conversion circuit 610, thereby performing surge protection on the output end of the DCDC power conversion circuit 610.

[0069] In a possible embodiment, the auxiliary power supply 630 is used to power the surge protection circuit 620, so that after the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, the first end of the surge protection circuit 620 outputs an indication voltage, which is used to indicate that the voltage at the output end of the DCDC power conversion circuit 610 has been discharged.

[0070] For example, refer to Figure 5 , taking the surge end voltage threshold of 1V as an example, the auxiliary power supply 630 can provide a voltage of 3.3V to the voltage regulating circuit 621, and the voltage regulating circuit 621 is used to regulate the 3.3V voltage output by the auxiliary power supply 630, so that after the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, the first end of the surge protection circuit 620 outputs a 1V indication voltage, and the 1V indication voltage is used to indicate that the voltage at the output end of the DCDC power conversion circuit 610 has been discharged. Thus, the controller 640 can determine that the voltage at the output end of the DCDC power conversion circuit 610 has been discharged and the surge at the output end of the DCDC power conversion circuit 610 has ended when the voltage at the output end of the DCDC power conversion circuit 610 is equal to 1V after the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610.

[0071] Compared with the above-mentioned optimizer 110 that uses passive surge protection devices for surge protection, in the optimizer 600 provided in the embodiment of the present application, the surge protection circuit 620 implements surge protection through the first resistor R1 and the switch tube Q, so that there is no need to use multi-level high-specification passive surge protection devices to implement surge protection, which can avoid the high cost of the optimizer 600. When surges occur multiple times, the possibility of failure of the first resistor R1 and the switch tube Q is lower than the possibility of failure of the passive surge protection device, thereby improving the reliability of the optimizer 600.

[0072] Optionally, the switch tube Q and each switch tube in the following embodiments include an insulate-gate bipolar transistor (IGBT) or a metal oxide semiconductor field effect transistor, which is not limited in the embodiments of the present application. Figure 5 In the embodiment of the present application, the switch tube Q includes a metal oxide semiconductor field effect transistor as an example for illustrative description.

[0073] Optionally, the voltage regulating circuit 621 includes a voltage dividing resistor, a low dropout linear regulator (LDO) or a BUCK circuit, which is not limited in the embodiment of the present application.

[0074] In a possible embodiment, the DCDC power conversion circuit 610 includes a BUCK circuit, a BOOST circuit, or a BUCK-BOOST circuit, which is not limited in the embodiment of the present application. Figure 5 In the embodiment of the present application, a DCDC power conversion circuit 610 including a BUCK circuit is used as an example for illustrative description. Specifically, the DCDC power conversion circuit 610 includes a first metal oxide semiconductor field effect transistor MOS1, a second metal oxide semiconductor field effect transistor MOS2 and an inductor L. The first metal oxide semiconductor field effect transistor MOS1 and the inductor L are connected in series between an input terminal and an output terminal of the DCDC power conversion circuit 610, and the second metal oxide semiconductor field effect transistor MOS2 is connected to a connection point between the first metal oxide semiconductor field effect transistor MOS1 and the inductor L.

[0075] In one possible embodiment, continue to refer to Figure 5After the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, when the voltage at the output end of the DCDC power conversion circuit 610 is equal to the surge end voltage threshold, the controller 640 controls the surge protection circuit 620 to stop discharging the energy at the output end of the DCDC power conversion circuit 610, and controls the DCDC power conversion circuit 610 to perform power conversion on the direct current outputted by the photovoltaic array 200, including: after the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, when the voltage at the output end of the DCDC power conversion circuit 610 is equal to the surge end voltage threshold, the switch tube Q in the surge protection circuit 620 is turned off, and the first metal oxide semiconductor field effect transistor MOS1 and the second metal oxide semiconductor field effect transistor MOS2 in the DCDC power conversion circuit 610 are alternately turned on to restore the working state of the optimizer 600, so that the DCDC power conversion circuit 610 performs power conversion on the direct current outputted by the photovoltaic array 200.

[0076] In one possible embodiment, continue to refer to Figure 5 The optimizer 600 also includes a driving circuit 650, which is arranged between the controller 640 and the DCDC power conversion circuit 610. The driving circuit 650 is used to receive a control signal sent by the controller 640 and generate a driving signal according to the control signal to control the conduction or shutdown of the switch tube in the DCDC power conversion circuit 610.

[0077] In a possible embodiment, the driving circuit 650 includes a bootstrap half-bridge driving IC or a push-pull circuit, which is not limited in the embodiment of the present application.

[0078] In a possible embodiment, the DCDC power conversion circuit 610 is used to perform maximum power point tracking (MPPT) on the connected photovoltaic array 200 .

[0079] In the optimizer 600 provided in the embodiment of the present application, when the voltage at the output end of the DCDC power conversion circuit 610 is greater than or equal to the surge voltage threshold, the controller 640 controls the DCDC power conversion circuit 610 to stop power conversion of the direct current output by the photovoltaic array 200, and controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, thereby achieving surge protection and avoiding damage to components in the DCDC power conversion circuit 610. After the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, the voltage at the output end of the DCDC power conversion circuit 610 is equal to the surge end voltage threshold. When the voltage at the output end of the DCDC power conversion circuit 610 indicates that the surge at the output end of the DCDC power conversion circuit 610 is over, the controller 640 controls the surge protection circuit 620 to stop discharging the energy at the output end of the DCDC power conversion circuit 610, and controls the DCDC power conversion circuit 610 to perform power conversion on the DC power output by the photovoltaic array 200, so that the controller 640 can timely control the DCDC power conversion circuit 610 in the optimizer 600 to resume the working state, and can avoid the low efficiency of the photovoltaic power generation system 400. It can be understood that the voltage at the output end of the DCDC power conversion circuit 610 can indicate whether the surge is over, so that the optimizer 600 and the inverter 420 can perform protection and adjustment, thereby improving the reliability of the photovoltaic power generation system 400. At the same time, there is no need to use multiple levels of high-specification passive surge protection devices with a higher probability of failure, which can reduce the cost of the photovoltaic power generation system 400.

[0080] In a possible embodiment, Figure 6 As shown, the optimizer 600 provided in the embodiment of the present application also includes a pass-through circuit 660 connected in parallel with the DCDC power conversion circuit 610 .

[0081] The controller 640 is also used to control the pass-through circuit 660 to be in a shutdown state when the voltage at the output end of the DCDC power conversion circuit 610 is greater than or equal to the surge voltage threshold, thereby avoiding damage to the components in the pass-through circuit 660 and improving the reliability of the optimizer 600.

[0082] In one possible embodiment, referring to Figure 6The pass-through circuit 660 includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, a positive channel metal oxide semi-conductor field effect transistor PMOS, and a negative channel metal oxide semi-conductor field effect transistor NMOS. One end of the third resistor R3 and the source (source, S) end of the PMOS are connected to the input end of the pass-through circuit 660, the drain (drain, D) end of the PMOS is connected to the output end of the pass-through circuit, the gate (gate, G) end of the PMOS is connected to one end of the fourth resistor R4, the other end of the third resistor R3 and the other end of the fourth resistor R4 are connected to the drain end of the NMOS, the source end of the NMOS is connected to the ground end, the third resistor R3 and the fourth resistor R4 are connected to the connection point B, the gate end of the NMOS is connected to the first end of the fifth resistor R5, and the other end of the fifth resistor R5 is connected to the controller 640.

[0083] Compared with the above-mentioned optimizer 110, which uses a bootstrap capacitor driver IC or a driver IC driven by a built-in charge pump to drive the first metal oxide semiconductor field effect transistor MOS1 in a continuously on state to achieve a pass-through mode, the pass-through circuit 660 does not need to use a bootstrap capacitor driver IC, and thus does not need to design a transformer in the auxiliary power supply 630 of the optimizer 600, which can avoid the problems of high complexity, large size, high cost and introduction of noise interference in the optimizer 600, and does not need to use a driver IC driven by a built-in charge pump, thereby avoiding the problem that the driver IC driven by a built-in charge pump needs to be customized and has a high cost.

[0084] Continue to refer to Figure 6 , the controller 640 controls the through circuit 660 to be in the off state, including: the controller 640 controls the NMOS to be turned on, pulls the potential of the connection point B down to 0V, and under the action of the third resistor R3 and the fourth resistor R4 of the voltage divider, the driving voltage VGS of the PMOS is less than 0, and the PMOS will be turned on, thereby controlling the through circuit 660 to be in the through state. The controller 640 is also used to control the NMOS to be turned off. At this time, the third resistor R3 and the fourth resistor R4 of the voltage divider are connected in series, the driving voltage VGS of the PMOS is 0, and the PMOS will be turned off, thereby controlling the through circuit 660 to be in the off state.

[0085] In a possible embodiment, IGBT or triode may be used to replace the above-mentioned PMOS and NMOS, which is not limited in the embodiment of the present application.

[0086] In one possible embodiment, continue to refer to Figure 6, the controller 640 is also used to control the DCDC power conversion circuit 610 to stop power conversion of the DC power output by the photovoltaic array 200, and control the direct-pass circuit 660 to be in a direct-pass state when the input current of the DCDC power conversion circuit 610 is greater than or equal to the current threshold and the voltage at the output end of the DCDC power conversion circuit 610 is less than the surge voltage threshold. The embodiment of the present application does not limit the specific value of the current threshold. Therefore, when there is no surge at the output end of the DCDC power conversion circuit 610, and the DCDC power conversion circuit 610 is not required to perform power conversion on the DC power output by the photovoltaic array 200, and the output current of the photovoltaic array 200 is reduced, for example, when the photovoltaic array 200 is not blocked, the optimizer 600 can directly transmit the DC power output by the photovoltaic array 200 to the inverter 420.

[0087] In one possible embodiment, continue to refer to Figure 6 , the controller 640 is also used to control the DCDC power conversion circuit 610 to stop power conversion of the DC power outputted by the photovoltaic array 200 and control the pass-through circuit 660 to be in a pass-through state after the surge protection circuit 620 is controlled to discharge the energy at the output end of the DCDC power conversion circuit 610, when the voltage at the output end of the DCDC power conversion circuit 610 is equal to the surge end voltage threshold, and the input current of the DCDC power conversion circuit 610 is greater than or equal to the current threshold. Thus, after the surge at the output end of the DCDC power conversion circuit 610 ends, the controller 640 can timely control the pass-through circuit 660 in the optimizer 600 to resume the working state, and when the DCDC power conversion circuit 610 is not required to perform power conversion on the DC power outputted by the photovoltaic array 200 and the output current of the photovoltaic array 200 is reduced, for example, when the photovoltaic array 200 is not blocked, the optimizer 600 can directly transmit the DC power outputted by the photovoltaic array 200 to the inverter 420.

[0088] The optimizer 600 provided in the embodiment of the present application further includes a through circuit 660 connected in parallel with the DCDC power conversion circuit 610. When the voltage at the output end of the DCDC power conversion circuit 610 is greater than or equal to the surge voltage threshold, the controller 640 controls the through circuit 660 to be in an off state, thereby avoiding damage to the components in the through circuit 660 and improving the reliability of the optimizer 600. Compared with the above-mentioned optimizer 110, which uses a bootstrap capacitor driver IC or a driver IC driven by a built-in charge pump to drive the first metal oxide semiconductor field effect transistor MOS1 to be in a continuous on state to achieve a through mode, the through circuit 660 does not need to use a bootstrap capacitor driver IC, so there is no need to design a transformer in the auxiliary power supply 630 of the optimizer 600, which can avoid the problems of high complexity, large volume, high cost and introduction of noise interference in the optimizer 600, and does not need to use a driver IC driven by a built-in charge pump, thereby avoiding the problem that the driver IC driven by the built-in charge pump needs to be customized and has a high cost.

[0089] like Figure 7 As shown, an embodiment of the present application further provides a control method for an optimizer, which is applied to the above-mentioned optimizer 600, and the method includes steps S701-S702.

[0090] S701, when the voltage at the output end of the DCDC power conversion circuit 610 is greater than or equal to the surge voltage threshold, the controller 640 controls the DCDC power conversion circuit 610 to stop power conversion of the direct current output by the photovoltaic array 200, and controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610. The embodiment of the present application does not limit the specific value of the surge voltage threshold.

[0091] In a possible embodiment, when the voltage at the output end of the DCDC power conversion circuit 610 is less than the surge voltage threshold, the controller 640 controls the DCDC power conversion circuit 610 to perform power conversion on the DC power output by the photovoltaic array 200 .

[0092] S702, after the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, when the voltage at the output end of the DCDC power conversion circuit 610 is equal to the surge end voltage threshold, the controller 640 controls the surge protection circuit 620 to stop discharging the energy at the output end of the DCDC power conversion circuit 610, and controls the DCDC power conversion circuit 610 to perform power conversion on the direct current output by the photovoltaic array 200, and the surge end voltage threshold is less than the surge voltage threshold. The embodiment of the present application does not limit the specific value of the surge end voltage threshold.

[0093] In a possible embodiment, after the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, if the voltage at the output end of the DCDC power conversion circuit 610 is not equal to the surge end voltage threshold, the controller 640 repeats the above step S701.

[0094] In the control method of the optimizer provided in the embodiment of the present application, when the voltage at the output end of the DCDC power conversion circuit 610 is greater than or equal to the surge voltage threshold, the controller 640 controls the DCDC power conversion circuit 610 to stop power conversion of the direct current output by the photovoltaic array 200, and controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, thereby achieving surge protection and avoiding damage to the components in the DCDC power conversion circuit 610. After the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, the voltage at the output end of the DCDC power conversion circuit 610 is equal to the surge end voltage threshold. When the voltage at the output end of the DCDC power conversion circuit 610 indicates that the surge at the output end of the DCDC power conversion circuit 610 is over, the controller 640 controls the surge protection circuit 620 to stop discharging the energy at the output end of the DCDC power conversion circuit 610, and controls the DCDC power conversion circuit 610 to perform power conversion on the DC power output by the photovoltaic array 200, so that the controller 640 can timely control the DCDC power conversion circuit 610 in the optimizer 600 to resume the working state, and can avoid the low efficiency of the photovoltaic power generation system 400. It can be understood that the voltage at the output end of the DCDC power conversion circuit 610 can indicate whether the surge is over, so that the optimizer 600 and the inverter 420 can perform protection and adjustment, thereby improving the reliability of the photovoltaic power generation system 400. At the same time, there is no need to use multiple levels of high-specification passive surge protection devices with a higher probability of failure, which can reduce the cost of the photovoltaic power generation system 400.

[0095] In one possible embodiment, referring to Figure 6 , the optimizer 600 further includes a pass-through circuit 660 connected in parallel with the DCDC power conversion circuit 610, such as Figure 8 As shown, the control method of the optimizer provided in the embodiment of the present application also includes step S703, and step S703 is executed simultaneously with the above step S701.

[0096] S703 : When the voltage at the output end of the DCDC power conversion circuit 610 is greater than or equal to the surge voltage threshold, the controller 640 controls the pass circuit 660 to be in an off state.

[0097] In the control method of the optimizer provided in the embodiment of the present application, the controller 640 controls the pass-through circuit 660 to be in an off state when the voltage at the output end of the DCDC power conversion circuit 610 is greater than or equal to the surge voltage threshold, thereby avoiding damage to the components in the pass-through circuit 660 and improving the reliability of the optimizer 600.

[0098] In a possible embodiment, Figure 8 As shown, when the input current of the DCDC power conversion circuit 610 is greater than or equal to the current threshold, and the voltage at the output end of the DCDC power conversion circuit 610 is less than the surge voltage threshold, and no surge occurs at the output end of the DCDC power conversion circuit 610, the control method of the optimizer provided in the embodiment of the present application also includes step S704, which can be performed before the above-mentioned step S701.

[0099] S704, when the input current of the DCDC power conversion circuit 610 is greater than or equal to the current threshold, and the voltage at the output end of the DCDC power conversion circuit 610 is less than the surge voltage threshold, the controller 640 controls the DCDC power conversion circuit 610 to stop power conversion of the direct current output by the photovoltaic array 200, and controls the pass-through circuit 660 to be in a pass-through state. The embodiment of the present application does not limit the specific value of the current threshold.

[0100] In a possible embodiment, when the input current of the DCDC power conversion circuit 610 is less than the current threshold and the voltage at the output end of the DCDC power conversion circuit 610 is less than the surge voltage threshold, the controller 640 controls the DCDC power conversion circuit 610 to perform power conversion on the direct current output by the photovoltaic array 200 and controls the pass-through circuit 660 to be in an off state.

[0101] In the control method of the optimizer provided in the embodiment of the present application, when the input current of the DCDC power conversion circuit 610 is greater than or equal to the current threshold and the voltage at the output end of the DCDC power conversion circuit 610 is less than the surge voltage threshold, the controller 640 controls the DCDC power conversion circuit 610 to stop power conversion of the direct current output by the photovoltaic array 200, and controls the pass-through circuit 660 to be in a pass-through state, so that no surge occurs at the output end of the DCDC power conversion circuit 610, and the DCDC power conversion circuit 610 is not required to perform power conversion on the direct current output by the photovoltaic array 200. When the output current of the photovoltaic array 200 is reduced, for example, when the photovoltaic array 200 is not blocked, the optimizer 600 can directly transmit the direct current output by the photovoltaic array 200 to the inverter 420.

[0102] In a possible embodiment, Figure 8As shown, after the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, the voltage at the output end of the DCDC power conversion circuit 610 is equal to the surge end voltage threshold, and the input current of the DCDC power conversion circuit 610 is greater than or equal to the current threshold. The control method of the optimizer provided in the embodiment of the present application also includes step S705. This step S705 and the above-mentioned step S702 can be selected to be executed based on the relationship between the input current of the DCDC power conversion circuit 610 and the current threshold.

[0103] S705, after the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, when the voltage at the output end of the DCDC power conversion circuit 610 is equal to the surge end voltage threshold, and the input current of the DCDC power conversion circuit 610 is greater than or equal to the current threshold, the controller 640 controls the DCDC power conversion circuit 610 to stop power conversion of the direct current output by the photovoltaic array 200, and controls the pass-through circuit 660 to be in a pass-through state.

[0104] In one possible embodiment, referring to Figure 8 In the above step S702, the controller 640 controls the DCDC power conversion circuit 610 to perform power conversion on the DC power output by the photovoltaic array 200, including: the controller 640 controls the DCDC power conversion circuit 610 to perform power conversion on the DC power output by the photovoltaic array 200, and controls the pass-through circuit 660 to be in an off state.

[0105] In the control method of the optimizer provided in the embodiment of the present application, after the controller 640 controls the surge protection circuit 620 to discharge the energy at the output end of the DCDC power conversion circuit 610, when the voltage at the output end of the DCDC power conversion circuit 610 is equal to the surge end voltage threshold, and the input current of the DCDC power conversion circuit 610 is greater than or equal to the current threshold, the controller 640 controls the DCDC power conversion circuit 610 to stop power conversion of the DC power output by the photovoltaic array 200, and controls the pass-through circuit 660 to be in a pass-through state. Thus, after the surge at the output end of the DCDC power conversion circuit 610 ends, the controller 640 can timely control the pass-through circuit 660 in the optimizer 600 to resume the working state, and when the DCDC power conversion circuit 610 is not required to perform power conversion on the DC power output by the photovoltaic array 200 and the output current of the photovoltaic array 200 is reduced, for example, when the photovoltaic array 200 is not blocked, the optimizer 600 can directly transmit the DC power output by the photovoltaic array 200 to the inverter 420.

[0106] Based on this, Figure 3As shown, the embodiment of the present application also provides a photovoltaic power generation system 400, which includes optimizers 411 to 41m and an inverter 420, where m is a positive integer, and the circuit topology of any optimizer in the optimizer 411 to 41m can be as described above. Figures 4 to 6 The circuit topology of the optimizer 600 is shown in FIG. Figure 3 Each optimizer can be used to connect to a photovoltaic array, for example, optimizer 411 is used to connect to photovoltaic array 511, and optimizer 41m is used to connect to photovoltaic array 51n, where n is a positive integer. The output ends of the m optimizers from optimizer 411 to optimizer 41m are connected in series and then connected to the input end of inverter 420, and the output end of inverter 420 is used to connect to the power grid or load 300.

[0107] Photovoltaic arrays 511 to 51n are used to convert solar energy into direct current. After power conversion by correspondingly connected optimizers 411 to 41m, the direct current output by the m optimizers is connected in series to the input end of the inverter 420. The inverter 420 is used to convert direct current into alternating current and transmit it to the power grid or load 300.

[0108] The above detailed description of the optimizer 600 and the analysis of the beneficial effects can be correspondingly referred to the control method of the optimizer and the photovoltaic power generation system 400, and the embodiments of the present application will not be repeated here.

[0109] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An optimizer, characterized in that: The optimizer includes a DCDC power conversion circuit, a surge protection circuit, an auxiliary power supply and a controller; The input end of the DCDC power conversion circuit is used to connect to the photovoltaic array, the output end of the DCDC power conversion circuit and the first end of the surge protection circuit are used to connect to the inverter, the second end of the surge protection circuit is connected to the output end of the auxiliary power supply, and the auxiliary power supply is used to power the surge protection circuit; The controller is used to control the DCDC power conversion circuit to stop power conversion of the direct current output by the photovoltaic array when the voltage at the output end of the DCDC power conversion circuit is greater than or equal to the surge voltage threshold, and control the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit; The controller is further used to control the surge protection circuit to stop discharging the energy at the output end of the DCDC power conversion circuit, and control the DCDC power conversion circuit to perform power conversion on the direct current output by the photovoltaic array when the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold after controlling the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit, and the surge end voltage threshold is less than the surge voltage threshold.

2. The optimizer according to claim 1, characterized in that The surge protection circuit includes a first resistor, a switch tube, a second resistor and a voltage regulating circuit; One end of the first resistor is connected to the first end of the surge protection circuit, the other end of the first resistor is connected to the first end of the switch tube, the second end of the switch tube is connected to the first end of the voltage regulation circuit, the second end of the voltage regulation circuit is connected to the second end of the surge protection circuit, the control end of the switch tube is connected to one end of the second resistor, the other end of the second resistor is connected to the controller, and the voltage regulation circuit is used to adjust the voltage output by the auxiliary power supply so that the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold.

3. The optimizer according to claim 2, characterized in that The voltage regulating circuit includes a voltage dividing resistor, a low voltage drop linear regulator or a BUCK circuit.

4. The optimizer according to any one of claims 1 to 3, characterized in that: The optimizer also includes a pass-through circuit connected in parallel with the DCDC power conversion circuit; The controller is further configured to control the pass-through circuit to be in an off state when the voltage at the output end of the DCDC power conversion circuit is greater than or equal to a surge voltage threshold.

5. The optimizer according to claim 4, characterized in that The controller is further used to control the DCDC power conversion circuit to stop power conversion of the direct current output by the photovoltaic array and control the pass-through circuit to be in a pass-through state when the input current of the DCDC power conversion circuit is greater than or equal to the current threshold and the voltage at the output end of the DCDC power conversion circuit is less than the surge voltage threshold.

6. The optimizer according to claim 5, characterized in that The controller is further configured to control the DCDC power conversion circuit to stop power conversion of the direct current output by the photovoltaic array, and control the pass-through circuit to be in a pass-through state, when the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold and the input current of the DCDC power conversion circuit is greater than or equal to the current threshold, after controlling the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit.

7. The optimizer according to any one of claims 4 to 6, characterized in that: The through circuit includes a third resistor, a fourth resistor, a fifth resistor, a PMOS and an NMOS; One end of the third resistor and the source end of the PMOS are connected to the input end of the pass-through circuit, the drain end of the PMOS is connected to the output end of the pass-through circuit, the gate end of the PMOS is connected to one end of the fourth resistor, the other end of the third resistor and the other end of the fourth resistor are connected to the drain end of the NMOS, the source end of the NMOS is connected to the ground end, the gate end of the NMOS is connected to the first end of the fifth resistor, and the other end of the fifth resistor is connected to the controller.

8. The optimizer according to any one of claims 1 to 7, characterized in that: The DCDC power conversion circuit is used to perform maximum power point tracking (MPPT) on the connected photovoltaic array.

9. A control method for an optimizer, characterized in that: Applied to the optimizer, the method comprises: When the voltage at the output end of the DCDC power conversion circuit is greater than or equal to the surge voltage threshold, the DCDC power conversion circuit is controlled to stop power conversion of the direct current output by the photovoltaic array, and the surge protection circuit is controlled to discharge the energy at the output end of the DCDC power conversion circuit; After controlling the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit, when the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold, controlling the surge protection circuit to stop discharging the energy at the output end of the DCDC power conversion circuit, and controlling the DCDC power conversion circuit to perform power conversion on the direct current output by the photovoltaic array, and the surge end voltage threshold is less than the surge voltage threshold; The input end of the DCDC power conversion circuit is used to connect the photovoltaic array, the output end of the DCDC power conversion circuit and the first end of the surge protection circuit are used to connect the inverter, the second end of the surge protection circuit is connected to the output end of the auxiliary power supply, and the auxiliary power supply is used to power the surge protection circuit.

10. The control method of the optimizer according to claim 9, characterized in that: The optimizer further includes a pass-through circuit connected in parallel with the DCDC power conversion circuit, and the method further includes: When the voltage at the output end of the DCDC power conversion circuit is greater than or equal to the surge voltage threshold, the pass circuit is controlled to be in an off state.

11. The control method of the optimizer according to claim 10, characterized in that: The method further comprises: When the input current of the DCDC power conversion circuit is greater than or equal to the current threshold, and the voltage at the output end of the DCDC power conversion circuit is less than the surge voltage threshold, the DCDC power conversion circuit is controlled to stop power conversion of the direct current output by the photovoltaic array, and the pass-through circuit is controlled to be in a pass-through state.

12. The control method of the optimizer according to claim 11, characterized in that: The method further comprises: After controlling the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit, when the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold, and the input current of the DCDC power conversion circuit is greater than or equal to the current threshold, the DCDC power conversion circuit is controlled to stop power conversion of the direct current output by the photovoltaic array, and the pass-through circuit is controlled to be in a pass-through state.

13. A photovoltaic power generation system, characterized in that: The photovoltaic power generation system includes an optimizer and an inverter connected to the optimizer, wherein the input end of the optimizer is used to connect to a photovoltaic array, the output end of the inverter is used to connect to a power grid or a load, the optimizer is used to perform power conversion on the direct current output by the photovoltaic array, and the inverter is used to convert the direct current after power conversion into alternating current and transmit it to the power grid or the load; wherein the optimizer includes a DCDC power conversion circuit, a surge protection circuit, an auxiliary power supply and a controller; The input end of the DCDC power conversion circuit is used to connect to the photovoltaic array, the output end of the DCDC power conversion circuit and the first end of the surge protection circuit are used to connect to the inverter, the second end of the surge protection circuit is connected to the output end of the auxiliary power supply, and the auxiliary power supply is used to power the surge protection circuit; The controller is used to control the DCDC power conversion circuit to stop power conversion of the direct current output by the photovoltaic array when the voltage at the output end of the DCDC power conversion circuit is greater than or equal to the surge voltage threshold, and control the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit; The controller is further used to control the surge protection circuit to stop discharging the energy at the output end of the DCDC power conversion circuit, and control the DCDC power conversion circuit to perform power conversion on the direct current output by the photovoltaic array when the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold after controlling the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit, and the surge end voltage threshold is less than the surge voltage threshold.

14. The photovoltaic power generation system according to claim 13, characterized in that: The optimizer also includes a pass-through circuit connected in parallel with the DCDC power conversion circuit; The controller is further configured to control the pass-through circuit to be in an off state when the voltage at the output end of the DCDC power conversion circuit is greater than or equal to a surge voltage threshold.

15. The photovoltaic power generation system according to claim 14, characterized in that: The controller is further used to control the DCDC power conversion circuit to stop power conversion of the direct current output by the photovoltaic array and control the pass-through circuit to be in a pass-through state when the input current of the DCDC power conversion circuit is greater than or equal to the current threshold and the voltage at the output end of the DCDC power conversion circuit is less than the surge voltage threshold.

16. The photovoltaic power generation system according to claim 15, characterized in that: The controller is further configured to control the DCDC power conversion circuit to stop power conversion of the direct current output by the photovoltaic array, and control the pass-through circuit to be in a pass-through state, when the voltage at the output end of the DCDC power conversion circuit is equal to the surge end voltage threshold and the input current of the DCDC power conversion circuit is greater than or equal to the current threshold, after controlling the surge protection circuit to discharge the energy at the output end of the DCDC power conversion circuit.

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