Control method of inverter system and electronic device

Abstract

The disclosure provides a control method of an inverter system and an electronic device, and relates to the technical field of power electronics. The inverter system comprises a voltage conversion circuit and an inverter circuit. The control method of the inverter system comprises the following steps: acquiring an electrical parameter of the voltage conversion circuit; determining whether a control mode of the voltage conversion circuit meets a switching condition according to the electrical parameter; in the case where the control mode meets the switching condition, performing mode switching on the control mode, and the mode switching is used to realize mutual switching between a closed-loop control mode and an open-loop control mode; wherein, in the case where the control mode is the open-loop control mode, a switch tube of the voltage conversion circuit is driven at a fixed frequency and a fixed duty cycle, and in the case where the control mode is the closed-loop control mode, the switch tube of the voltage conversion circuit is driven at a variable frequency and a variable duty cycle. The embodiment of the disclosure can reduce the switching loss of the voltage conversion circuit and improve the overall conversion efficiency of the system.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of power electronics, and particularly relates to a control method of an inverter system and an electronic device. BACKGROUND

[0002] A photovoltaic grid-connected inverter is a core component of a photovoltaic grid-connected system. In the photovoltaic grid-connected inverter, a two-stage inverter has advantages of high safety, reduced maintenance cost, and high reliability. The two-stage inverter usually has a corresponding DC / DC conversion circuit and a DC / AC conversion circuit. When the DC / DC conversion circuit adopts a Buck circuit, a closed-loop control mode is usually adopted, and the switching frequency is constant. However, when the Buck circuit is in a large duty cycle working condition, if the Buck circuit still maintains a high fixed switching frequency, unnecessary switching loss will be increased. SUMMARY

[0003] The present disclosure provides a control method of an inverter system and an electronic device, which can reduce the redundant switching loss of the Buck circuit of the inverter system caused by the fixed frequency strategy.

[0004] In a first aspect, the present disclosure provides a control method of an inverter system, the inverter system having a voltage conversion circuit and an inverter circuit, the control method comprising: obtaining an electrical parameter of the voltage conversion circuit; determining whether a control mode of the voltage conversion circuit satisfies a switching condition according to the electrical parameter; performing mode switching on the control mode in a case where the control mode satisfies the switching condition, the mode switching being used to realize mutual switching between a closed-loop control mode and an open-loop control mode; wherein, in a case where the control mode is the open-loop control mode, a switch tube of the voltage conversion circuit is driven at a fixed frequency and a fixed duty cycle, and in a case where the control mode is the closed-loop control mode, the switch tube of the voltage conversion circuit is driven at a variable frequency and a variable duty cycle.

[0005] In an optional implementation manner, before the determining whether the control mode of the voltage conversion circuit satisfies the switching condition according to the electrical parameter, the method further comprises: obtaining a current control mode of the voltage conversion circuit; the electrical parameter comprises a power parameter, and in a case where the current control mode is the open-loop control mode, the determining whether the control mode of the voltage conversion circuit satisfies the switching condition according to the electrical parameter comprises: determining whether the current control mode satisfies a first switching condition of switching from the open-loop control mode to the closed-loop control mode according to the power parameter.

[0006] In an optional implementation, the electrical parameter further includes a voltage parameter or a duty cycle parameter, and in a case where the current control mode is the closed-loop control mode, the determining, according to the electrical parameter, whether the control mode of the voltage conversion circuit satisfies the switching condition includes: determining, according to the voltage parameter, whether the current control mode satisfies a second switching condition of switching from the closed-loop control mode to the open-loop control mode; or determining, according to the duty cycle parameter, whether the current control mode satisfies the second switching condition of switching from the closed-loop control mode to the open-loop control mode.

[0007] In an optional implementation, the voltage parameter includes an input voltage and an output voltage, and the determining, according to the voltage parameter, whether the current control mode satisfies the second switching condition of switching from the closed-loop control mode to the open-loop control mode includes: determining a voltage difference between the input voltage and the output voltage; and comparing the voltage difference with a preset voltage threshold, and in a case where the voltage difference is less than the preset voltage threshold, determining that the current control mode satisfies the second switching condition of switching from the closed-loop control mode to the open-loop control mode.

[0008] In an optional implementation, the determining, according to the duty cycle parameter, whether the current control mode satisfies the second switching condition of switching from the closed-loop control mode to the open-loop control mode includes: in a case where the duty cycle parameter is greater than a preset duty cycle threshold, determining that the current control mode satisfies the second switching condition of switching from the closed-loop control mode to the open-loop control mode.

[0009] In an optional implementation, the power parameter includes an output power, and the determining, according to the power parameter, whether the current control mode satisfies the first switching condition of switching from the open-loop control mode to the closed-loop control mode includes: determining a power variation of the output power of the voltage conversion circuit within a preset time; comparing the power variation with a preset variation threshold, and in a case where the power variation is greater than the preset variation threshold, determining that the current control mode satisfies the first switching condition of switching from the open-loop control mode to the closed-loop control mode.

[0010] In an optional implementation, the driving the switch tube of the voltage conversion circuit at a variable frequency and a variable duty cycle includes: for any time point, determining a switch frequency value corresponding to a duty cycle value of the time point according to the duty cycle value and a preset mapping relationship between the duty cycle and the switch frequency; and driving the switch tube of the voltage conversion circuit according to the duty cycle value and the switch frequency value.

[0011] In an optional implementation, the determining the switching frequency value corresponding to the duty cycle value according to the duty cycle value and a preset mapping relationship between the duty cycle and the switching frequency comprises: in a case where the duty cycle value is in a first interval, determining the switching frequency value as a first frequency value, the first frequency value being a lower limit value of the frequency corresponding to the closed-loop control mode; in a case where the duty cycle value is in a second interval, determining the switching frequency value as a second frequency value, the second frequency value being an upper limit value of the frequency corresponding to the closed-loop control mode; in a case where the duty cycle value is in a third interval, the switching frequency value varies with the duty cycle value, and the switching frequency value is in a frequency interval between the first frequency value and the second frequency value.

[0012] In an optional implementation, the driving the switching tube of the voltage conversion circuit at the fixed frequency and the fixed duty cycle comprises: driving the switching tube of the voltage conversion circuit according to a maximum duty cycle value corresponding to the voltage conversion circuit and a third frequency value; the third frequency value is less than a fourth frequency value corresponding to the voltage conversion circuit, the fourth frequency value being used to represent a preset switching frequency of the voltage conversion circuit; and the first frequency value is greater than or equal to the fourth frequency value.

[0013] In an optional implementation, the voltage conversion circuit is a Buck circuit, and in a case where a plurality of Buck circuits are provided, output ends of the plurality of Buck circuits are connected in series.

[0014] In an optional implementation, the inverter system comprises an inverter, the inverter comprising at least one Buck circuit and the inverter circuit.

[0015] In an optional implementation, the inverter system comprises at least one optimizer and an inverter, the optimizer comprising at least one Buck circuit, and the inverter being the inverter circuit; an input end of the inverter is connected to an output end of the optimizer, and in a case where a plurality of optimizers are provided, output ends of the plurality of optimizers are connected in series.

[0016] In a second aspect, the present disclosure provides an electronic device, comprising: at least one processor; and a memory connected to the at least one processor in communication; wherein the memory stores one or more computer programs executable by the at least one processor, and the one or more computer programs are executed by the at least one processor to enable the at least one processor to perform the control method of the inverter system described above.

[0017] The control method for the inverter system provided in this embodiment first obtains the electrical parameters of the voltage conversion circuit; then, based on the electrical parameters, it determines whether the control mode of the voltage conversion circuit meets the switching conditions; finally, if the control mode meets the switching conditions, the control mode is switched, and the mode switching is used to realize the mutual switching between closed-loop control mode and open-loop control mode; wherein, when the control mode is open-loop control mode, the switching transistor of the voltage conversion circuit is driven with a fixed frequency and a fixed duty cycle, and when the control mode is closed-loop control mode, the switching transistor of the voltage conversion circuit is driven with a variable frequency and a variable duty cycle.

[0018] Therefore, this embodiment of the present disclosure, for the voltage conversion circuit, uses a variable frequency and variable duty cycle to drive the switching transistor in closed-loop control, while using a fixed frequency and duty cycle in open-loop control. Thus, this embodiment of the present disclosure can adjust the closed-loop control mode of the voltage conversion circuit from a fixed-frequency control mode to a variable-frequency control mode. Furthermore, this embodiment of the present disclosure adds an open-loop control mode in addition to the closed-loop control mode, thereby combining the two control modes to reduce the switching losses of the voltage conversion circuit and improve the overall conversion efficiency of the system.

[0019] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the embodiments of the present disclosure to explain the disclosure and do not constitute a limitation thereof. The above and other features and advantages will become more apparent to those skilled in the art from the detailed description of exemplary embodiments with reference to the accompanying drawings, in which:

[0021] Figure 1 A flowchart of a control method for an inverter system provided in this embodiment of the present disclosure;

[0022] Figure 2 This is a schematic diagram of a topology for an inverter system.

[0023] Figure 3 This is another schematic diagram of the topology of the inverter system;

[0024] Figure 4 This is a schematic diagram of another topology of the inverter system;

[0025] Figure 5 This is a flowchart illustrating the control method of the inverter system when the drive timing is the first timing.

[0026] Figure 6 This is a flowchart illustrating the control method of the inverter system when the driving timing is the second timing.

[0027] Figure 7 This is a schematic diagram illustrating the mapping relationship between duty cycle and switching frequency.

[0028] Figure 8 This is a waveform diagram showing the change in switching frequency of the switching transistor in the voltage conversion circuit over time during control mode switching.

[0029] Figure 9 A block diagram of a control device for an inverter system provided in an embodiment of this disclosure;

[0030] Figure 10 This is a block diagram of an electronic device provided in an embodiment of the present disclosure. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of this disclosure, exemplary embodiments of this disclosure are described below with reference to the accompanying drawings, including various details of the embodiments of this disclosure to aid understanding. These should be considered merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this disclosure. Similarly, for clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0032] Where there is no conflict, the various embodiments of this disclosure and the features thereof in the embodiments may be combined with each other.

[0033] As used herein, the term “and / or” includes any and all combinations of one or more related enumerated entries.

[0034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, the singular forms “a” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising” and / or “made of” are used in this specification, the presence of the stated feature, integral, step, operation, element, and / or component is specified, but the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof is not excluded. Words such as “connected” or “linked” are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect.

[0035] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted as having an idealized or overly formal meaning, unless expressly so defined herein.

[0036] Grid-connected photovoltaic (PV) inverters are the core components of PV grid-connected systems, playing a crucial role in converting solar energy into usable grid-connected electricity. Among PV grid-connected inverters, two-stage inverters offer advantages such as high safety, reduced maintenance costs, and high reliability. Two-stage inverters typically have corresponding DC / DC and DC / AC circuits. When the DC / DC circuit uses a Buck circuit, a closed-loop control method is usually employed, maintaining a constant switching frequency. However, when the Buck circuit operates under conditions with a high duty cycle, a lower switching frequency is sufficient to meet the circuit's actual output performance requirements. Maintaining a higher, fixed switching frequency would increase unnecessary switching losses.

[0037] In view of this, the present disclosure provides a control method for an inverter system. First, the electrical parameters of the voltage conversion circuit are obtained; then, based on the electrical parameters, it is determined whether the control mode of the voltage conversion circuit meets the switching conditions; finally, if the control mode meets the switching conditions, the control mode is switched, and the mode switching is used to realize the mutual switching between closed-loop control mode and open-loop control mode; wherein, when the control mode is open-loop control mode, the switching transistor of the voltage conversion circuit is driven with a fixed frequency and a fixed duty cycle, and when the control mode is closed-loop control mode, the switching transistor of the voltage conversion circuit is driven with a variable frequency and a variable duty cycle.

[0038] Therefore, in this embodiment of the voltage conversion circuit, a variable frequency and duty cycle are used to drive the switching transistor in closed-loop control, while a fixed frequency and duty cycle are used in open-loop control. Thus, this embodiment can change the closed-loop control mode of the voltage conversion circuit from a fixed-frequency control mode to a variable-frequency control mode. Furthermore, in addition to the closed-loop control mode, this embodiment also adds an open-loop control mode, thereby combining these two control modes to reduce switching losses in the voltage conversion circuit and improve the overall conversion efficiency of the system.

[0039] In a first aspect, embodiments of this disclosure provide a control method for an inverter system. Figure 1 A flowchart illustrating a control method for an inverter system provided in an embodiment of this disclosure. (Refer to...) Figure 1 The method includes:

[0040] Step S110: Obtain the electrical parameters of the voltage conversion circuit.

[0041] The inverter system includes a voltage conversion circuit and an inverter circuit. The inverter system can be composed of an inverter or a combination of an inverter and an optimizer; this disclosure does not limit this aspect.

[0042] In one alternative implementation, the voltage conversion circuit in the inverter system is a Buck circuit, and if there are multiple Buck circuits, the outputs of the multiple Buck circuits are connected in series.

[0043] In one alternative implementation, the inverter system includes an inverter, which includes at least one of the aforementioned Buck circuits and an inverter circuit.

[0044] For ease of understanding, Figure 2 A schematic diagram of a topology of an inverter system is shown, with reference to... Figure 2 In an inverter system built around an inverter, the inverter includes at least one Buck circuit and an inverter circuit (i.e., Figure 2 (The DC / AC circuit in the inverter). The output of the Buck circuit is connected to the input of the DC / AC circuit. In the case of a single Buck circuit in the inverter, its output is connected to the input of the DC / AC circuit. In the case of multiple Buck circuits in the inverter, their outputs are connected in series to the input of the DC / AC circuit. For each Buck circuit, such as the first Buck circuit, its output can be determined by the input voltage V. in1 Switch S1, freewheeling diode D 1’ Filter inductor L1, capacitor C1, output voltage V o1 and output current I L Composition. Output voltage V o1 This can be the voltage across capacitor C1. For the nth Buck circuit, it can be determined by the input voltage V. inn Switch S n Freewheeling diode D n’ Filter inductor L n Capacitor C n Output voltage V on Composition. Output voltage V on It can be capacitor C n The voltage at both ends.

[0045] Therefore, in Figure 2 In an inverter system topology, the number of voltage conversion circuits included can be one or more. Figure 2Each Buck circuit in the inverter system is a voltage conversion circuit. Correspondingly, Figure 2 The DC / AC circuit in the inverter system is the inverter circuit.

[0046] In addition, it should be noted that, Figure 2 Only the Buck circuit in the inverter system is shown as a first-type structure. In practical applications, the specific structure of the Buck circuit in this disclosure is not limited. For ease of understanding, Figure 3 This shows another schematic diagram of the inverter system topology.

[0047] Reference Figure 3 In an inverter system built around an inverter, each Buck circuit in the system has a second-type structure. Specifically, this Buck circuit is a half-bridge circuit, and each Buck circuit consists of two switching transistors. It should be noted that... Figure 3 In the inverter system, two symmetrical half-bridge circuits (i.e., Buck circuits) can also be used as a group of Buck circuits. Thus, the controller can synchronously output drive signals to the four switches in this group for conduction control, and the switches in the same half-bridge circuit employ a complementary conduction strategy.

[0048] In other words, when an inverter system includes Buck circuits of the second type described above, the number of Buck circuits in the inverter system must be multiple, specifically an even number, with two adjacent symmetrical Buck circuits forming a group. Correspondingly, the inverter system can include multiple groups of Buck circuits, with the outputs of each group connected in series.

[0049] in, Figure 3 Each Buck circuit group includes a first half-bridge circuit (i.e., the first Buck circuit) and a second half-bridge circuit (i.e., the second Buck circuit). The first half-bridge circuit includes a first switching transistor S. 11 The second half-bridge circuit includes a second switch S2, a third switch S3, and a fourth switch S4. The first switch S... 11 The first terminal (e.g., the source) of the second switching transistor S2 is connected to the second terminal (e.g., the drain) of the second switching transistor S2, which is connected to the first input voltage V. ina The first switching transistor S 11 The inductance L connecting the second terminal to the first terminal of the second switch S2 m The first terminal. The second terminal of the third switch S3 is connected to the first terminal of the fourth switch S4, which is connected to the second input voltage V. in2 The inductance L connecting the first terminal of the third switch S3 and the second terminal of the fourth switch m The second end.

[0050] In one alternative implementation, the inverter system includes at least one optimizer and an inverter. The optimizer includes at least one Buck circuit. The inverter is an inverter circuit. The input of the inverter is connected to the output of the optimizer. If there are multiple optimizers, the outputs of the multiple optimizers are connected in series.

[0051] For ease of understanding, Figure 4 Another topology diagram of the inverter system is shown, with reference to... Figure 4 The inverter system is constructed by combining inverters and optimizers. In this inverter system, photovoltaic modules are connected to the input terminals of the optimizers. Furthermore, the n optimizers are connected in series (n≥1), meaning the output terminals of the n optimizers are connected in series. Each optimizer includes at least one Buck circuit; that is, each optimizer consists of a single Buck circuit or multiple Buck circuits connected in series. Accordingly, when an optimizer includes multiple Buck circuits, the output terminals of each Buck circuit within the optimizer are connected in series. The number of optimizers in the inverter system can be single or multiple. When the inverter system contains only a single optimizer, the output terminal of that optimizer is connected to the input terminal of the inverter. When the inverter system contains multiple optimizers, the output terminals of each optimizer are connected in series to the input terminal of the inverter. The inverter can be a single-stage DC / AC circuit or a two-stage DC / DC circuit combined with a DC / AC circuit; this disclosure does not limit this.

[0052] Correspondingly, in Figure 4 In the inverter system topology, the voltage conversion circuit in the inverter system is... Figure 4 The Buck circuit in the optimizer, and the inverter circuit in the inverter system are... Figure 4 The inverter in the system. That is to say, in an inverter system consisting of an optimizer and an inverter, the number of voltage conversion circuits included can be one or more. Figure 4 Each Buck circuit included in the optimizer is a voltage conversion circuit in the inverter system.

[0053] In one alternative implementation, the electrical parameters of the voltage conversion circuit can be obtained by acquiring parameters of the voltage conversion circuit. For example, electrical parameters such as the input voltage, output voltage, and output current of the voltage conversion circuit can be acquired, and this disclosure does not limit this.

[0054] It should be noted that if the inverter system includes multiple voltage conversion circuits, the electrical parameters corresponding to each voltage conversion circuit can be collected separately to obtain the electrical parameters corresponding to each voltage conversion circuit. This disclosure does not limit this.

[0055] Step S120: Determine whether the control mode of the voltage conversion circuit meets the switching conditions based on the electrical parameters.

[0056] The control mode of the voltage conversion circuit can include an open-loop control mode and a closed-loop control mode. Therefore, in this embodiment, the voltage conversion circuit can dynamically switch between open-loop and closed-loop control modes.

[0057] It should be noted that if the inverter system includes multiple voltage conversion circuits, then for each voltage conversion circuit, the control mode of the voltage conversion circuit can be determined according to the corresponding electrical parameters to determine whether the switching conditions are met. This disclosure does not impose any restrictions on this.

[0058] In one alternative implementation, before determining whether the control mode of the voltage conversion circuit meets the switching conditions based on the electrical parameters, the method further includes: obtaining the current control mode of the voltage conversion circuit; the electrical parameters include power parameters, and when the current control mode is an open-loop control mode, the above-mentioned determination of whether the control mode of the voltage conversion circuit meets the switching conditions based on the electrical parameters includes: determining whether the current control mode meets the first switching condition for switching from the open-loop control mode to the closed-loop control mode based on the power parameters.

[0059] In this embodiment, the current operating state of the voltage conversion circuit can be read from a preset register at any given time, thereby obtaining the current control mode of the voltage conversion circuit at that time. Alternatively, the current control mode of the voltage conversion circuit can be determined based on the duty cycle parameter or the input and output voltages of the voltage conversion circuit; this embodiment does not impose any limitations on this. The input and output voltages can be obtained by sampling the voltage conversion circuit, and the duty cycle parameter can be obtained by reading the duty cycle register; this embodiment does not impose any limitations on this.

[0060] In addition, regarding Figure 3 The output voltage of the Buck circuit of the second type can be calculated from the input voltage and the duty cycle parameter, and the embodiments disclosed herein do not limit this.

[0061] Furthermore, for each voltage conversion circuit in the inverter system, its corresponding current control mode can be obtained separately, and this disclosure does not limit this.

[0062] The power parameter can include the output power of the voltage conversion circuit. Accordingly, the output power of each voltage conversion circuit in the inverter system can be obtained separately. Specifically, for each voltage conversion circuit in the inverter system, the output power can be calculated based on the obtained output voltage and output current of that voltage conversion circuit.

[0063] When the current control mode is open-loop control, the first switching condition for switching from open-loop control to closed-loop control can be determined based on the power parameters. For example, for any voltage conversion circuit in an inverter system, the control mode needs to be switched from open-loop control to closed-loop control based on the power change of the output power of the voltage conversion circuit.

[0064] In this embodiment of the disclosure, by obtaining the current control mode of the voltage conversion circuit, and when the current control mode is an open-loop control mode, the accurate switching condition matching for switching the current control mode from the open-loop control mode to the closed-loop control mode is achieved based on the power parameters of the voltage conversion circuit.

[0065] In one optional implementation, the electrical parameters also include voltage parameters or duty cycle parameters. When the current control mode is a closed-loop control mode, the above-mentioned determination of whether the control mode of the voltage conversion circuit meets the switching conditions based on the electrical parameters includes: determining whether the current control mode meets the second switching condition for switching from closed-loop control mode to open-loop control mode based on the voltage parameters; or, determining whether the current control mode meets the second switching condition for switching from closed-loop control mode to open-loop control mode based on the duty cycle parameters.

[0066] The voltage parameters may include the input voltage and output voltage of the voltage conversion circuit. Accordingly, if the inverter system includes multiple voltage conversion circuits, the corresponding input voltage and output voltage can be obtained for each voltage conversion circuit in the inverter system. This disclosure does not impose any limitations on this aspect.

[0067] The duty cycle parameter is the duty cycle of the switching transistor in the voltage conversion circuit.

[0068] For example, when the current control mode is closed-loop control, the second switching condition for switching from closed-loop control to open-loop control can be determined based on the voltage parameters. For instance, for any voltage conversion circuit in an inverter system, the control mode can be determined to switch from closed-loop control to open-loop control based on the voltage difference between the input and output voltages of the voltage conversion circuit.

[0069] For example, when the current control mode is a closed-loop control mode, the second switching condition for switching from closed-loop control mode to open-loop control mode can be determined based on the duty cycle parameter. For instance, for any voltage conversion circuit in an inverter system, the control mode can be determined to switch from closed-loop control mode to open-loop control mode based on the comparison between the duty cycle parameter of the voltage conversion circuit and a preset duty cycle threshold. In this embodiment, by obtaining the current control mode of the voltage conversion circuit, and when the current control mode is a closed-loop control mode, accurate matching of the switching condition for switching from closed-loop control mode to open-loop control mode is achieved based on the voltage parameter or duty cycle parameter of the voltage conversion circuit.

[0070] In addition, it should be noted that in the above Figure 3 In the inverter system architecture, considering that its Buck circuit is a second type structure (i.e., a half-bridge circuit structure), the second switching condition judgment for switching from closed-loop control mode to open-loop control mode can be made based on the duty cycle parameter in the Buck circuit. Alternatively, the output voltage of the Buck circuit can be further calculated based on the duty cycle parameter in the Buck circuit and the input voltage, and then the second switching condition judgment for switching from closed-loop control mode to open-loop control mode can be made based on the output voltage of the Buck circuit. This disclosure embodiment does not limit this approach.

[0071] In one optional implementation, the power parameter includes the output power. Based on the power parameter, it is determined whether the current control mode meets the first switching condition for switching from open-loop control mode to closed-loop control mode. This includes: determining the power change of the output power of the voltage conversion circuit within a preset time period; comparing the power change with a preset change threshold; and determining that the current control mode meets the first switching condition for switching from open-loop control mode to closed-loop control mode if the power change is greater than the preset change threshold.

[0072] The preset time is the time interval between the current output power acquisition time in the open-loop control mode and the previous output power acquisition time.

[0073] For example, the process of acquiring the output power of the voltage conversion circuit in three consecutive steps is as follows: At time T1, the output power of the voltage conversion circuit is acquired once. At this time, the current control mode of the voltage conversion circuit is open-loop control mode. Suppose that the control mode of the voltage conversion circuit is switched from open-loop control mode to closed-loop control mode. Correspondingly, at time T2, the output power of the voltage conversion circuit is acquired again. At this time, the current control mode of the voltage conversion circuit is closed-loop control mode. Suppose that the control mode of the voltage conversion circuit is switched again, switching from closed-loop control mode to open-loop control mode. Correspondingly, at time T3, the output power of the voltage conversion circuit is acquired again. At this time, the current control mode of the voltage conversion circuit is open-loop control mode.

[0074] Therefore, in this case, the power change is determined by the power difference between the output power obtained at time T3 and the output power obtained at time T2.

[0075] It should be noted that, in this embodiment of the present disclosure, the corresponding power change amount can be determined for each voltage conversion circuit in the inverter system, and the second switching condition for the voltage conversion circuit can be matched according to the comparison result of the power change amount and the preset change threshold.

[0076] The preset change threshold is used to measure the magnitude of the power change. For any voltage conversion circuit in the inverter system, if the power change of the voltage conversion circuit is greater than the preset change threshold, it indicates that the output power change of the voltage conversion circuit exceeds the allowable range of the circuit. Therefore, in this case, it is determined that the current control mode of the voltage conversion circuit meets the first switching condition, so that its current control mode can be switched from open-loop control mode to closed-loop control mode in a timely manner.

[0077] In addition, it should be noted that in the above Figure 3 Under the inverter system structure, considering that its Buck circuit is a second-type structure (i.e., a half-bridge circuit structure), it is possible to... Figure 3 Each Buck circuit in the group can be controlled in an independent mode, or the two Buck circuits included in each group of Buck circuits can be controlled in a unified mode. This disclosure does not limit this.

[0078] Accordingly, when determining the first switching condition for switching from open-loop control mode to closed-loop control mode, it is possible to target... Figure 3 Each Buck circuit in the process can be judged independently, or a unified judgment can be made for each group of Buck circuits. This disclosure does not limit this approach.

[0079] When making a unified judgment for each group of Buck circuits, if the power change of the output power of any Buck circuit in the group is greater than a preset change threshold, then the current control mode of the group of Buck circuits is determined to meet the first switching condition for switching from open-loop control mode to closed-loop control mode.

[0080] For example, refer to Figure 3 When the power change of the output power of either half-bridge circuit in the two Buck circuits (i.e., the two half-bridge circuits) in the Buck circuit group is detected to be greater than the preset change threshold, the current control mode of the Buck circuit group can be switched from open-loop control mode to closed-loop control mode.

[0081] In this embodiment of the disclosure, for the voltage conversion circuit, by determining the amount of power change of its output power within a preset time, when the amount of power change is greater than a preset change threshold, it is determined that the first switching condition is met, thereby timely switching the current control mode from the open-loop control mode to the closed-loop control mode.

[0082] In one optional implementation, the voltage parameters include the input voltage and the output voltage. Based on the voltage parameters, it is determined whether the current control mode meets the second switching condition for switching from closed-loop control mode to open-loop control mode. This includes: determining the voltage difference between the input voltage and the output voltage; comparing the voltage difference with a preset voltage threshold; and if the voltage difference is less than the preset voltage threshold, determining that the current control mode meets the second switching condition for switching from closed-loop control mode to open-loop control mode.

[0083] For the first type of Buck circuit, its input and output voltages can be directly measured through the circuit. For the second type of Buck circuit, i.e., for... Figure 3 In the Buck circuit, the input voltage and duty cycle parameters of the Buck circuit can be measured first, and then the output voltage of the circuit can be calculated based on the input voltage and duty cycle parameters.

[0084] The preset voltage threshold is used to measure the difference between the input voltage and the output voltage. The value of the preset voltage threshold can be set according to the actual application needs, and this embodiment does not limit this.

[0085] For any voltage conversion circuit in the inverter system, if the voltage difference between the input voltage and the output voltage of the voltage conversion circuit is less than a preset voltage threshold, it indicates that the input voltage and output voltage are relatively close, i.e., the input voltage is approximately equal to the output voltage. Therefore, in this case, the control mode is determined to meet the second switching condition, and the current control mode is switched from closed-loop control mode to open-loop control mode.

[0086] Furthermore, it should be noted that for each voltage conversion circuit in the inverter system, the second switching condition can be matched based on the comparison result between the voltage difference between its input voltage and output voltage and the preset voltage threshold. This disclosure does not limit this aspect.

[0087] For example, targeting Figure 2 The first Buck circuit in the calculation is based on its input voltage V. in1 With output voltage V o1 The voltage difference between them, so that when the voltage difference is less than a preset voltage threshold, it indicates that V in1 With V o1 If they are approximately equal, switch the current control mode from closed-loop control mode to open-loop control mode.

[0088] In this embodiment of the disclosure, for the voltage conversion circuit, by determining the voltage difference between its input voltage and output voltage, when the voltage difference is less than a preset voltage threshold, it is determined that the second switching condition is met, thereby enabling timely switching of the current control mode from closed-loop control mode to open-loop control mode.

[0089] In one optional implementation, the determination of whether the current control mode meets the second switching condition for switching from closed-loop control mode to open-loop control mode is based on the duty cycle parameter, including: if the duty cycle parameter is greater than a preset duty cycle threshold, the determination that the current control mode meets the second switching condition for switching from closed-loop control mode to open-loop control mode is made.

[0090] The preset duty cycle threshold is used to measure the magnitude of the duty cycle parameter. The value of the preset duty cycle threshold can be adapted to the actual application needs, and this embodiment does not impose any limitations on it.

[0091] For any voltage conversion circuit in an inverter system, its output voltage Vo = duty cycle parameter D × input voltage Vin. If the duty cycle parameter of this voltage conversion circuit is greater than a preset duty cycle threshold, it indicates that the duty cycle value is relatively large, such as approximately 1. Therefore, the input voltage and output voltage of this voltage conversion circuit are quite close, i.e., the input voltage is approximately equal to the output voltage. Accordingly, in this case, the control mode is determined to meet the second switching condition, thus switching the current control mode from closed-loop control mode to open-loop control mode.

[0092] Furthermore, it should be noted that for any voltage conversion circuit in the inverter system, the second switching condition can be matched based on the comparison result between its duty cycle parameter and the preset duty cycle threshold. This disclosure does not limit this.

[0093] For example, targetingFigure 2 The first Buck circuit in the circuit compares its duty cycle parameter with a preset duty cycle threshold. Therefore, when the duty cycle parameter is greater than the preset duty cycle threshold, it indicates that its V... in1 With V o1 If they are approximately equal, switch the current control mode from closed-loop control mode to open-loop control mode.

[0094] For example, targeting Figure 3 , can be Figure 3 Each Buck circuit in the system can be controlled in an independent mode, or the two Buck circuits included in each group of Buck circuits can be controlled in a unified mode; this embodiment does not limit this. Correspondingly, when determining the second switching condition for switching from closed-loop control mode to open-loop control mode, it can be based on... Figure 3 Each Buck circuit in the process can be judged independently, or a unified judgment can be made for each group of Buck circuits. This disclosure does not limit this approach.

[0095] For example, when making an independent judgment for each Buck circuit, if the duty cycle parameter of the target switch in the Buck circuit is greater than the preset duty cycle threshold, then it is determined that its current control mode meets the second switching condition for switching from closed-loop control mode to open-loop control mode.

[0096] When making a unified judgment for each group of Buck circuits, if the duty cycle parameter of the target switch of any Buck circuit in the group is greater than the preset duty cycle threshold, then the current control mode of the group of Buck circuits is determined to meet the second switching condition for switching from closed-loop control mode to open-loop control mode.

[0097] For example, refer to Figure 3 When the target switch S of two Buck circuits (i.e. two half-bridge circuits) in the Buck circuit group is detected 11 When the duty cycle of S3 is 1, both Buck circuits are in a shoot-through state. Alternatively, when the target switch S is detected... 11 When any duty cycle in S3 is 1, one of the two half-bridge circuits is in a shoot-through state. Therefore, under this condition, the current control mode of the two Buck circuits in this group can be switched from closed-loop control mode to open-loop control mode. When it is detected that both half-bridge circuits in the Buck circuit group are in a shoot-through state, such as when the target switch S is detected... 11 When the duty cycle of S3 is approximately 1, the Buck circuit group can switch from closed-loop control mode to open-loop control mode.

[0098] In this embodiment of the disclosure, for the voltage conversion circuit, when the duty cycle parameter is greater than the preset duty cycle threshold, it can be determined that the second switching condition is met, so that the current control mode can be switched from the closed-loop control mode to the open-loop control mode in a timely manner.

[0099] Step S130: When the control mode meets the switching conditions, the control mode is switched. The mode switching is used to switch between closed-loop control mode and open-loop control mode. Specifically, in the open-loop control mode, the switching transistor of the voltage conversion circuit is driven with a fixed frequency and a fixed duty cycle. In the closed-loop control mode, the switching transistor of the voltage conversion circuit is driven with a variable frequency and a variable duty cycle.

[0100] Specifically, for any voltage conversion circuit in the inverter system, if its current control mode is open-loop control mode and the current control mode meets the first switching condition, its current control mode can be switched to closed-loop control mode; if its current control mode is closed-loop control mode and the current control mode meets the second switching condition, its current control mode can be switched to open-loop control mode.

[0101] It should be noted that if the switching conditions for the control mode are not met, the current control mode can be maintained. For example, for any voltage conversion circuit in an inverter system, if its current control mode is open-loop control and the first switching condition is not met, the current control mode will remain open-loop control. If its current control mode is closed-loop control and the second switching condition is not met, the current control mode will remain closed-loop control.

[0102] Correspondingly, for any voltage conversion circuit in an inverter system, if its control mode is open-loop control mode, its switching transistor is always driven by a fixed frequency and a fixed duty cycle, while if its control mode is closed-loop control mode, its switching transistor can be driven by a variable frequency and a variable duty cycle.

[0103] The values ​​of the fixed frequency and fixed duty cycle can be adaptively set according to actual needs, and this embodiment does not limit them. For example, the fixed frequency value can be set to 15kHz, and the fixed duty cycle can be 1 or a value close to 1, such as 0.997.

[0104] Specifically, for any voltage conversion circuit in the inverter system, when its control mode is closed-loop control, it is in the frequency conversion control stage, and the switching frequency can dynamically change within a preset frequency range to meet the dynamic response and stability requirements of the circuit. Correspondingly, the duty cycle also dynamically changes within the range of 0 to 1.

[0105] It should also be noted that steps S110 to S130 can be repeated to obtain dynamic electrical parameters of the voltage conversion circuit and switch the dynamic control mode of the voltage conversion circuit.

[0106] Furthermore, the embodiments of this disclosure do not impose specific limitations on the driving timing of the switching transistor in the voltage conversion circuit. The driving timing can be a first timing, meaning that for the voltage conversion circuit, after obtaining its current control mode, the switching transistor can be driven according to the driving method corresponding to the current control mode. The driving timing can also be a second timing, meaning that after performing a switching condition matching judgment, if the switching condition is met, the switching transistor is driven according to the driving method corresponding to the switched control mode; or if the switching condition is not met, the switching transistor is driven according to the driving method corresponding to the maintained current control mode.

[0107] In one optional implementation, the driving timing of the switching transistor of the voltage conversion circuit is either a first timing or a second timing: when the driving timing is the first timing, after obtaining the current control mode of the voltage conversion circuit and before determining whether the control mode of the voltage conversion circuit meets the switching conditions, the method further includes: driving the switching transistor of the voltage conversion circuit according to the driving method corresponding to the current control mode; when the driving timing is the second timing, after determining whether the control mode of the voltage conversion circuit meets the switching conditions, the method further includes: if the current control mode meets the switching conditions, driving the switching transistor of the voltage conversion circuit according to the driving method corresponding to the switched control mode; if the current control mode does not meet the switching conditions, driving the switching transistor of the voltage conversion circuit according to the driving method corresponding to the current control mode.

[0108] The driving methods for each control mode can be referred to the description above. In open-loop control mode, the corresponding driving method is to drive the switching transistor with a fixed frequency and a fixed duty cycle. In closed-loop control mode, the corresponding driving method is to drive the switching transistor with a variable frequency and a variable duty cycle.

[0109] In other words, when the driving timing is the first timing, after acquiring the current control mode of the voltage conversion circuit but before determining whether the control mode of the voltage conversion circuit meets the switching conditions, the switching transistor can be driven directly according to the driving method corresponding to the acquired current control mode. When the driving timing is the second timing, the switching transistor needs to be driven according to the driving method corresponding to the final obtained control mode after the switching condition matching judgment. The only difference between the two is the timing relationship between the switching condition matching judgment and the switching transistor driving operation.

[0110] For ease of understanding, Figure 5 A flowchart illustrating the control method of the inverter system when the drive timing is the first timing is shown. For each voltage conversion circuit in the inverter system, the control mode switching logic and switching transistor drive logic are the same; therefore, only the following is shown: Figure 2 Any voltage conversion circuit in (such as) Figure 2 The first Buck circuit in the example is used. (Refer to...) Figure 5 The method includes:

[0111] Step S401: Obtain the input voltage, output voltage, and output power of the first Buck circuit.

[0112] It should be noted that this refers to the second type of Buck circuit structure, namely... Figure 3 In the Buck circuit, the input voltage and duty cycle parameters of the Buck circuit can be obtained first, and the output voltage of the Buck circuit can be obtained based on the input voltage and duty cycle parameters.

[0113] Step S402: Obtain the current control mode of the first Buck circuit and determine whether the current control mode is a closed-loop control mode. If the current control mode is an open-loop control mode, execute step S403; if the current control mode is a closed-loop control mode, execute step S406.

[0114] Step S403: When the current control mode is open-loop control mode, drive the switching transistor S1 of the first Buck circuit with a fixed frequency f1 and a fixed duty cycle, and execute step S404.

[0115] Step S404: Compare the power change within a preset time period with a preset change threshold to determine if the power change exceeds the preset change threshold. If the power change exceeds the preset change threshold, proceed to step S405. If the power change does not exceed the preset change threshold, maintain the current control mode and return to step S401.

[0116] Step S405: If the power change is greater than the preset change threshold, determine that the current control mode meets the first switching condition, switch the current control mode from open-loop control mode to closed-loop control mode, and return to execute step S401.

[0117] Step S406: When the current control mode is closed-loop control mode, drive the switch S1 of the first Buck circuit with a variable frequency and a variable duty cycle, and execute step S407.

[0118] Step S407: Compare the voltage difference between the input voltage and the output voltage with a preset voltage threshold to determine whether the voltage difference is less than the preset voltage threshold. If the voltage difference is less than the preset voltage threshold, proceed to step S408; if the voltage difference is not less than the preset voltage threshold, maintain the current control mode and return to step S401.

[0119] Step S408: If the voltage difference is less than the preset change threshold, determine that the current control mode meets the second switching condition, switch the current control mode from closed-loop control mode to open-loop control mode, and return to execute step S401.

[0120] Furthermore, Figure 6 A flowchart illustrating the control method of the inverter system when the driving timing is the second timing is shown. For each voltage conversion circuit in the inverter system, the control mode switching logic and switching transistor driving logic are the same; therefore, only the following is shown: Figure 2 Any voltage conversion circuit (such as Figure 2 The first Buck circuit in the example is used. (Refer to...) Figure 6 The method includes:

[0121] Step S501: Obtain the input voltage, output voltage, and output power of the first Buck circuit.

[0122] It should be noted that this refers to the second type of Buck circuit structure, namely... Figure 3 In the Buck circuit, the input voltage and duty cycle parameters of the Buck circuit can be obtained first, and the output voltage of the Buck circuit can be obtained based on the input voltage and duty cycle parameters.

[0123] Step S502: Obtain the current control mode of the first Buck circuit and determine whether the current control mode is a closed-loop control mode. If the current control mode is an open-loop control mode, execute step S503; if the current control mode is a closed-loop control mode, execute step S507.

[0124] Step S503: Compare the power change within a preset time period with a preset change threshold to determine whether the power change exceeds the preset change threshold. If the power change exceeds the preset change threshold, proceed to step S504. If the power change does not exceed the preset change threshold, proceed to step S506.

[0125] Step S504: If the power change is greater than the preset change threshold, determine that the current control mode meets the first switching condition, switch the current control mode from open-loop control mode to closed-loop control mode, and execute step S505.

[0126] Step S505: Drive the switch S1 of the first Buck circuit with a variable frequency and a variable duty cycle, and return to execute step S501.

[0127] Step S506: If the power change is not greater than the preset change threshold, maintain the current control mode, drive the switch S1 of the first Buck circuit with a fixed frequency f1 and a fixed duty cycle, and return to execute step S501.

[0128] Step S507: Compare the voltage difference between the input voltage and the output voltage with a preset voltage threshold to determine whether the voltage difference is less than the preset voltage threshold. If the voltage difference is less than the preset voltage threshold, proceed to step S508; if the voltage difference is not less than the preset voltage threshold, proceed to step S510.

[0129] Step S508: If the voltage difference is less than the preset change threshold, determine that the current control mode meets the second switching condition, switch the current control mode from closed-loop control mode to open-loop control mode, and execute step S509.

[0130] Step S509: Drive the switching transistor S1 of the first Buck circuit with a fixed frequency f1 and a fixed duty cycle, and return to execute step S501.

[0131] Step S510: If the voltage difference is not less than the preset change threshold, maintain the current control mode, drive the switch S1 of the first Buck circuit with a variable frequency and a variable duty cycle, and return to execute step S501.

[0132] This disclosure provides a control method for an inverter system. First, the electrical parameters of the voltage conversion circuit are obtained. Then, based on the electrical parameters, it is determined whether the control mode of the voltage conversion circuit meets the switching conditions. Finally, if the control mode meets the switching conditions, the control mode is switched. The mode switching is used to realize the mutual switching between closed-loop control mode and open-loop control mode. In the case of open-loop control mode, the switching transistor of the voltage conversion circuit is driven with a fixed frequency and a fixed duty cycle. In the case of closed-loop control mode, the switching transistor of the voltage conversion circuit is driven with a variable frequency and a variable duty cycle.

[0133] Therefore, in this embodiment of the voltage conversion circuit, a variable frequency and duty cycle are used to drive the switching transistor in closed-loop control, while a fixed frequency and duty cycle are used in open-loop control. Thus, this embodiment can change the closed-loop control mode of the voltage conversion circuit from a fixed-frequency control mode to a variable-frequency control mode. Furthermore, in addition to the closed-loop control mode, this embodiment also adds an open-loop control mode, thereby combining these two control modes to reduce switching losses in the voltage conversion circuit and improve the overall conversion efficiency of the system.

[0134] In one alternative implementation, when driving the switching transistor of the voltage conversion circuit based on the changing frequency and the changing duty cycle, the duty cycle value at any given moment can be determined first, and then the switching frequency value corresponding to that duty cycle value can be determined according to the mapping relationship.

[0135] Accordingly, driving the switching transistor of the voltage conversion circuit with a variable frequency and a variable duty cycle includes: for any given moment, determining a switching frequency value corresponding to the duty cycle value based on the duty cycle value at that moment and a preset mapping relationship between the duty cycle and the switching frequency; and driving the switching transistor of the voltage conversion circuit based on the duty cycle value and the switching frequency value.

[0136] The duty cycle value ranges from 0 to 1. For any given duty cycle value, the corresponding switching frequency value can be determined according to a preset mapping relationship. In other words, there is a correlation between the duty cycle value and the switching frequency value.

[0137] Specifically, for any voltage conversion circuit in an inverter system, the output voltage V of the voltage conversion circuit is... o1 With input voltage V in1 The relationship between them is:

[0138] Formula (1)

[0139] Where D is the duty cycle of the switching transistor in the voltage conversion circuit, and T is the switching period of the switching transistor.s for:

[0140] Formula (2)

[0141] Among them, f s Let f be the switching frequency of the switching transistor. Therefore, from the above formulas (1) and (2), we can obtain the switching frequency f. s The relationship with duty cycle D is as follows:

[0142] Formula (3)

[0143] in, This refers to the change in inductor current in a voltage conversion circuit. Let f be the inductance value in the voltage conversion circuit. The switching frequency f can be further obtained from the above formula. s The relationship with duty cycle D is as follows:

[0144] Formula (4)

[0145] Therefore, the numerical mapping relationship between the duty cycle and the switching frequency can be obtained from the above formula (4). In addition, it should be noted that in practical applications, according to hardware and design limitations, an upper limit value can be set for the switching frequency, and according to the preset switching frequency of the voltage conversion circuit, a lower limit value can be set for the switching frequency, so that the switching frequency can dynamically change within the range between the lower limit value and the upper limit value.

[0146] Accordingly, in one optional implementation, the switching frequency value corresponding to the duty cycle is determined based on the duty cycle value at a given time and a preset mapping relationship between the duty cycle and the switching frequency. This includes: when the duty cycle value is in a first interval, the switching frequency value is determined to be a first frequency value, which is the lower limit of the frequency corresponding to the closed-loop control mode; when the duty cycle value is in a second interval, the switching frequency value is determined to be a second frequency value, which is the upper limit of the frequency corresponding to the closed-loop control mode; when the duty cycle value is in a third interval, the switching frequency value changes with the duty cycle value, and the switching frequency value is in the frequency range between the first frequency value and the second frequency value.

[0147] For ease of understanding, regarding the above formula (4), after setting the upper and lower frequency limits corresponding to the closed-loop control mode, Figure 7 A schematic diagram showing the mapping relationship between duty cycle value and switching frequency value is presented.

[0148] Reference Figure 7 Where D1, D2, D3, and D4 are preset duty cycle values. The first interval is... Figure 7The intervals are [0, D1) and [D4, 1]. Within the first interval, regardless of the duty cycle change, the switching frequency value is always the lower limit of the frequency corresponding to the closed-loop control mode (i.e., the first frequency value). Furthermore, to ensure the control stability of the closed-loop mode, this lower limit of the frequency is not less than the fourth frequency value corresponding to the voltage conversion circuit. The fourth frequency value is used to characterize the preset switching frequency of the voltage conversion circuit. For example, if the fourth frequency value is 20kHz, the lower limit of the frequency corresponding to the closed-loop control mode can be 25kHz.

[0149] The second interval is Figure 7 The interval is [D2, D3). Within the second interval, regardless of how the duty cycle changes, the switching frequency value is always the upper limit of the frequency corresponding to the closed-loop control mode (i.e., the second frequency value). For example, the upper limit of the frequency is set to 120kHz.

[0150] The third interval is Figure 7 The switching frequency is defined in the intervals [D1, D2) and [D3, D4). Within the third interval, according to formula (4) above, the switching frequency value changes with the duty cycle. Furthermore, the switching frequency value dynamically varies between the upper and lower frequency limits. Specifically, in the [D1, D2) interval, the switching frequency value increases with the increase of the duty cycle; for example, the switching frequency value dynamically changes between 25kHz and 120kHz, and the larger the duty cycle, the larger the switching frequency value. In the [D3, D4) interval, the switching frequency value decreases with the increase of the duty cycle; for example, the switching frequency value dynamically changes between 25kHz and 120kHz, and the larger the duty cycle, the smaller the switching frequency value.

[0151] In this embodiment of the disclosure, for any voltage conversion circuit in the inverter system, a frequency conversion control method is adopted in the closed-loop control mode. Its switching frequency value will follow the duty cycle value and dynamically change between the frequency range corresponding to the lower limit and upper limit of the frequency in the closed-loop control mode, so as to meet the dynamic response and stability requirements of the circuit.

[0152] In one optional implementation, driving the switching transistor of the voltage conversion circuit with a fixed frequency and a fixed duty cycle includes: driving the switching transistor of the voltage conversion circuit according to the maximum duty cycle value corresponding to the voltage conversion circuit and a third frequency value; wherein the third frequency value is less than the fourth frequency value corresponding to the voltage conversion circuit, the fourth frequency value is used to characterize the preset switching frequency of the voltage conversion circuit; and the first frequency value is greater than or equal to the fourth frequency value.

[0153] Due to hardware circuit limitations, the voltage conversion circuit has a corresponding maximum duty cycle value, such as 0.997. The maximum duty cycle value can be adaptively set according to actual application needs, and this embodiment does not impose any restrictions on it.

[0154] Among them, the switching frequency limit in the open-loop control mode is not restricted by the conditions of closed-loop stability. Therefore, the switching frequency of the open-loop control can be set to be lower than the fourth frequency value, which is used to characterize the preset switching frequency of the voltage conversion circuit, and the first frequency value is greater than or equal to the fourth frequency value. That is, in the embodiments of the present disclosure, the third frequency value needs to be less than the fourth frequency value corresponding to the voltage conversion circuit.

[0155] For example, if the fourth frequency value is 20 kHz, the switching frequency value corresponding to the open-loop control mode, that is, the third frequency value, can be set to 15 kHz.

[0156] In the embodiments of the present disclosure, in the open-loop control mode, the duty cycle of its switching transistor is the maximum duty cycle value, such as 1 or a value approaching 1. Thus, in the open-loop control mode, the switching transistor in the voltage conversion circuit is approximately in a continuously conducting state, which can effectively reduce the number of switching actions, and further reduce the driving loss of the switching transistor.

[0157] The embodiments of the present disclosure can achieve dynamic switching between the open-loop control mode and the closed-loop control mode of the voltage conversion circuit. For any voltage conversion circuit in the inverter system, when the output power in its open-loop control mode exceeds the threshold value allowed for change of this circuit, the control mode can be switched from the open-loop control mode to the closed-loop control mode.

[0158] When the voltage conversion circuit is in the closed-loop control mode, a variable-frequency control method is adopted. Its switching frequency value is higher than the fixed switching frequency value in the open-loop control mode, and moreover, the switching frequency value will dynamically change between the frequency range corresponding to the frequency lower limit value and the frequency upper limit value in the closed-loop control mode to meet the dynamic response and stability requirements of the circuit.

[0159] Correspondingly, when the voltage conversion circuit is in the closed-loop control mode, if its input voltage is approximately equal to the output voltage, its control mode can be switched from the closed-loop control mode to the open-loop control mode. In this mode, the duty cycle of its switching transistor is 1 or approaches 1. Thus, in this mode, the switching transistor in the voltage conversion circuit is approximately in a continuously conducting state, thereby effectively reducing the number of switching actions, and further reducing the driving loss of the switching transistor.

[0160] For the sake of easy understanding, Figure 8 a waveform diagram showing the change of the switching frequency of the switching transistor in the voltage conversion circuit over time during the control mode switching is shown.

[0161] Referring to Figure 8 , for any voltage conversion circuit in the inverter system, in the stage of 0 < t < t1, this voltage conversion circuit is in the closed-loop control mode. At this time, the switching frequency f of its switching transistor sThe frequency range is dynamically adjusted within the range of the lower limit (i.e., the first frequency value, such as 25kHz) to the upper limit (i.e., the second frequency value, such as 120kHz) to meet the dynamic response and stability requirements of the circuit. In the stage after t1, the voltage conversion circuit switches to open-loop control mode. At this time, the switching frequency of its switching transistor is fixed at a third frequency value, such as 15kHz, to reduce switching losses.

[0162] In addition, it should be noted that, regarding Figure 3 The inverter system includes a Buck circuit group. In order to minimize the inductor current ripple when the Buck circuit group is in closed-loop control mode, the switching transistors of the two Buck circuits in the Buck circuit group can also be set to a fixed switching frequency, such as a frequency upper limit of 120kHz. This disclosure does not limit this.

[0163] In other words, targeting Figure 3 In the second type of Buck circuit structure, under closed-loop control mode, the switching frequency of its switching transistor can dynamically vary within a range from the lower to the upper frequency limit, or it can maintain a fixed switching frequency at the upper frequency limit. Furthermore, when the Buck circuit dynamically varies within the range from the lower to the upper frequency limit, it can... Figure 3 All switching transistors in the same Buck circuit group must maintain the same switching frequency.

[0164] And when Figure 3 When the Buck circuit group is in open-loop control mode, the switching frequency of the switching transistors of the two Buck circuits in the group is not constrained by the closed-loop stability requirements. In this case, the switching frequency can be set lower than the preset control frequency, such as fixing the switching frequency at a third frequency value, like 15kHz.

[0165] It is understood that the various method embodiments mentioned above in this disclosure can be combined with each other to form combined embodiments without violating the principle and logic. Due to space limitations, this disclosure will not elaborate further. Those skilled in the art will understand that in the above methods of specific implementation, the specific execution order of each step should be determined by its function and possible internal logic.

[0166] In addition, this disclosure also provides a control device, electronic equipment, and computer-readable storage medium for an inverter, all of which can be used to implement the control method of any inverter system provided in this disclosure. The corresponding technical solutions and descriptions are described in the corresponding section of the method and will not be repeated here.

[0167] Figure 9 This is a block diagram of a control device for an inverter system provided in an embodiment of the present disclosure.

[0168] Reference Figure 9This disclosure provides a control device for an inverter system, which includes a voltage conversion circuit and an inverter circuit. The control device for the inverter system includes:

[0169] Acquisition module 81 is used to acquire the electrical parameters of the voltage conversion circuit;

[0170] The determination module 82 is used to determine whether the control mode of the voltage conversion circuit meets the switching conditions based on the electrical parameters.

[0171] The switching module 83 is used to switch the control mode when the control mode meets the switching conditions. The mode switching is used to realize the mutual switching between closed-loop control mode and open-loop control mode.

[0172] Specifically, in the case of open-loop control mode, the switching transistor of the voltage conversion circuit is driven with a fixed frequency and a fixed duty cycle; in the case of closed-loop control mode, the switching transistor of the voltage conversion circuit is driven with a variable frequency and a variable duty cycle.

[0173] In one alternative implementation, before determining whether the control mode of the voltage conversion circuit meets the switching conditions based on the electrical parameters, the device is further configured to: obtain the current control mode of the voltage conversion circuit;

[0174] The electrical parameters include power parameters. When the current control mode is an open-loop control mode, determining whether the control mode of the voltage conversion circuit meets the switching conditions based on the electrical parameters includes: determining whether the current control mode meets the first switching condition for switching from an open-loop control mode to a closed-loop control mode based on the power parameters.

[0175] In one optional implementation, the electrical parameters further include voltage parameters or duty cycle parameters. When the current control mode is a closed-loop control mode, determining whether the control mode of the voltage conversion circuit meets the switching conditions based on the electrical parameters includes: determining whether the current control mode meets the second switching condition for switching from a closed-loop control mode to an open-loop control mode based on the voltage parameters; or, determining whether the current control mode meets the second switching condition for switching from a closed-loop control mode to an open-loop control mode based on the duty cycle parameters.

[0176] In one optional implementation, the driving timing of the switching transistor of the voltage conversion circuit is a first timing or a second timing: when the driving timing is the first timing, after obtaining the current control mode of the voltage conversion circuit and before determining whether the control mode of the voltage conversion circuit meets the switching conditions, the device is further configured to: drive the switching transistor of the voltage conversion circuit according to the driving method corresponding to the current control mode; when the driving timing is the second timing, after determining whether the control mode of the voltage conversion circuit meets the switching conditions, the device is further configured to: when the current control mode meets the switching conditions, drive the switching transistor of the voltage conversion circuit according to the driving method corresponding to the switched control mode; when the current control mode does not meet the switching conditions, drive the switching transistor of the voltage conversion circuit according to the driving method corresponding to the current control mode.

[0177] In one optional implementation, the voltage parameters include an input voltage and an output voltage. Determining whether the current control mode meets the second switching condition for switching from a closed-loop control mode to an open-loop control mode based on the voltage parameters includes: determining the voltage difference between the input voltage and the output voltage; comparing the voltage difference with a preset voltage threshold; and determining that the current control mode meets the second switching condition for switching from a closed-loop control mode to an open-loop control mode if the voltage difference is less than the preset voltage threshold.

[0178] In one optional implementation, determining whether the current control mode meets the second switching condition for switching from closed-loop control mode to open-loop control mode based on the duty cycle parameter includes: determining that the current control mode meets the second switching condition for switching from closed-loop control mode to open-loop control mode when the duty cycle parameter is greater than a preset duty cycle threshold.

[0179] In one optional implementation, the power parameter includes output power. Determining whether the current control mode meets the first switching condition for switching from open-loop control mode to closed-loop control mode based on the power parameter includes: determining the power change of the output power of the voltage conversion circuit within a preset time period; comparing the power change with a preset change threshold; and determining that the current control mode meets the first switching condition for switching from open-loop control mode to closed-loop control mode if the power change is greater than the preset change threshold.

[0180] In one optional implementation, driving the switching transistor of the voltage conversion circuit with a variable frequency and a variable duty cycle includes: for any given time, determining a switching frequency value corresponding to the duty cycle value based on the duty cycle value at that time and a preset mapping relationship between the duty cycle and the switching frequency; and driving the switching transistor of the voltage conversion circuit based on the duty cycle value and the switching frequency value.

[0181] In one optional implementation, determining the switching frequency value corresponding to the duty cycle value based on the duty cycle value at the specified time and a preset mapping relationship between the duty cycle and the switching frequency includes: when the duty cycle value is in a first interval, determining the switching frequency value as a first frequency value, wherein the first frequency value is the lower frequency limit value corresponding to the closed-loop control mode; when the duty cycle value is in a second interval, determining the switching frequency value as a second frequency value, wherein the second frequency value is the upper frequency limit value corresponding to the closed-loop control mode; and when the duty cycle value is in a third interval, the switching frequency value changes with the duty cycle value, and the switching frequency value is in the frequency range between the first frequency value and the second frequency value.

[0182] In one optional implementation, driving the switching transistor of the voltage conversion circuit with a fixed frequency and a fixed duty cycle includes: driving the switching transistor of the voltage conversion circuit according to the maximum duty cycle value corresponding to the voltage conversion circuit and a third frequency value; wherein the third frequency value is less than a fourth frequency value corresponding to the voltage conversion circuit, and the fourth frequency value is used to characterize a preset switching frequency of the voltage conversion circuit; the first frequency value is greater than or equal to the fourth frequency value.

[0183] In one alternative implementation, the voltage conversion circuit is a Buck circuit, and when there are multiple Buck circuits, the output terminals of the multiple Buck circuits are connected in series.

[0184] In one alternative implementation, the inverter system includes an inverter that includes at least one of the Buck circuits and the inverter circuit.

[0185] In one alternative implementation, the inverter system includes at least one optimizer and an inverter, the optimizer including at least one Buck circuit, and the inverter being the inverter circuit; the input terminal of the inverter is connected to the output terminal of the optimizer, and in the case of multiple optimizers, the output terminals of the multiple optimizers are connected in series.

[0186] The various modules in the control device of the aforementioned inverter system can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0187] Figure 10 This is a block diagram of an electronic device provided in an embodiment of the present disclosure.

[0188] Reference Figure 10 This disclosure provides an electronic device, which includes: at least one processor 901; at least one memory 902; and one or more I / O interfaces 903 connected between the processor 901 and the memory 902; wherein the memory 902 stores one or more computer programs that can be executed by the at least one processor 901, and the one or more computer programs are executed by the at least one processor 901 to enable the at least one processor 901 to execute the control method of the inverter system described above.

[0189] The modules in the aforementioned electronic devices can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0190] This disclosure also provides a computer-readable storage medium storing a computer program thereon, wherein the computer program, when executed by a processor, implements the control method for the inverter system described above. The computer-readable storage medium may be volatile or non-volatile.

[0191] This disclosure also provides a computer program product, including computer-readable code, or a non-volatile computer-readable storage medium carrying computer-readable code. When the computer-readable code is run in the processor of an electronic device, the processor in the electronic device executes the control method of the inverter system described above.

[0192] Those skilled in the art will understand that all or some of the steps, systems, and apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit (ASIC). Such software can be distributed on a computer-readable storage medium, which may include computer storage media (or non-transitory media) and communication media (or transient media).

[0193] As is known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information, such as computer-readable program instructions, data structures, program modules, or other data. Computer storage media includes, but is not limited to, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), static random access memory (SRAM), flash memory or other memory technologies, portable compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, it is known to those skilled in the art that communication media typically contain computer-readable program instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0194] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0195] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0196] The computer program product described herein can be implemented specifically through hardware, software, or a combination thereof. In one alternative embodiment, the computer program product is specifically embodied in a computer storage medium; in another alternative embodiment, the computer program product is specifically embodied in a software product, such as a software development kit (SDK), etc.

[0197] Various aspects of this disclosure are described herein with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer-readable program instructions.

[0198] These computer-readable program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that, when executed by the processor of the computer or other programmable data processing apparatus, they create means for implementing the functions / actions specified in one or more blocks of the flowchart and / or block diagram. These computer-readable program instructions can also be stored in a computer-readable storage medium that causes a computer, programmable data processing apparatus, and / or other device to operate in a particular manner; thus, the computer-readable medium storing the instructions comprises an article of manufacture that includes instructions for implementing aspects of the functions / actions specified in one or more blocks of the flowchart and / or block diagram.

[0199] Computer-readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable data processing apparatus, or other device to produce a computer-implemented process, thereby causing the instructions executed on the computer, other programmable data processing apparatus, or other device to perform the functions / actions specified in one or more boxes of a flowchart and / or block diagram.

[0200] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of an instruction containing one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than those shown in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0201] Example embodiments have been disclosed herein, and while specific terminology has been used, it is for illustrative purposes only and should be construed as such, and is not intended to be limiting. In some instances, it will be apparent to those skilled in the art that features, characteristics, and / or elements described in connection with particular embodiments may be used alone, or in combination with features, characteristics, and / or elements described in connection with other embodiments, unless otherwise expressly indicated. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of this disclosure as set forth by the appended claims.

Claims

1. A control method for an inverter system, characterized in that, The inverter system includes a voltage conversion circuit and an inverter circuit, and the method includes: Obtain the electrical parameters of the voltage conversion circuit; Based on the electrical parameters, determine whether the control mode of the voltage conversion circuit meets the switching conditions; When the control mode meets the switching conditions, the control mode is switched, and the mode switching is used to realize the mutual switching between closed-loop control mode and open-loop control mode. Specifically, in the case of open-loop control mode, the switching transistor of the voltage conversion circuit is driven with a fixed frequency and a fixed duty cycle; in the case of closed-loop control mode, the switching transistor of the voltage conversion circuit is driven with a variable frequency and a variable duty cycle. The switching transistor that drives the voltage conversion circuit with a variable frequency and a variable duty cycle includes: For any given moment, based on the duty cycle value at that moment and the preset mapping relationship between the duty cycle and the switching frequency, the switching frequency value corresponding to the duty cycle value is determined; The switching transistor of the voltage conversion circuit is driven according to the duty cycle value and the switching frequency value. The step of determining the switching frequency value corresponding to the duty cycle value based on the duty cycle value at the specified time and the preset mapping relationship between the duty cycle and the switching frequency includes: When the duty cycle value is in the first interval, the switching frequency value is determined to be a first frequency value, and the first frequency value is the lower limit value of the frequency corresponding to the closed-loop control mode. When the duty cycle value is in the second interval, the switching frequency value is determined to be the second frequency value, and the second frequency value is the upper frequency limit value corresponding to the closed-loop control mode. When the duty cycle value is in the third interval, the switching frequency value changes with the duty cycle value, and the switching frequency value is in the frequency interval between the first frequency value and the second frequency value.

2. The method according to claim 1, characterized in that, Before determining whether the control mode of the voltage conversion circuit meets the switching conditions based on the electrical parameters, the method further includes: obtaining the current control mode of the voltage conversion circuit; The electrical parameters include power parameters. When the current control mode is an open-loop control mode, determining whether the control mode of the voltage conversion circuit meets the switching conditions based on the electrical parameters includes: Based on the power parameters, determine whether the current control mode meets the first switching condition for switching from open-loop control mode to closed-loop control mode.

3. The method according to claim 2, characterized in that, The electrical parameters also include voltage parameters or duty cycle parameters. When the current control mode is a closed-loop control mode, determining whether the control mode of the voltage conversion circuit meets the switching conditions based on the electrical parameters includes: Based on the voltage parameters, determine whether the current control mode meets the second switching condition for switching from closed-loop control mode to open-loop control mode; or... Based on the duty cycle parameter, determine whether the current control mode meets the second switching condition for switching from closed-loop control mode to open-loop control mode.

4. The method according to claim 3, characterized in that, The voltage parameters include input voltage and output voltage. Determining whether the current control mode meets the second switching condition for switching from closed-loop control mode to open-loop control mode based on the voltage parameters includes: Determine the voltage difference between the input voltage and the output voltage; The voltage difference is compared with a preset voltage threshold. If the voltage difference is less than the preset voltage threshold, the current control mode is determined to meet the second switching condition for switching from closed-loop control mode to open-loop control mode.

5. The method according to claim 3, characterized in that, The step of determining whether the current control mode meets the second switching condition for switching from closed-loop control mode to open-loop control mode based on the duty cycle parameter includes: If the duty cycle parameter is greater than the preset duty cycle threshold, the current control mode is determined to meet the second switching condition for switching from closed-loop control mode to open-loop control mode.

6. The method according to claim 2, characterized in that, The power parameters include output power. Determining whether the current control mode meets the first switching condition for switching from open-loop control mode to closed-loop control mode based on the power parameters includes: Determine the change in output power of the voltage conversion circuit within a preset time period; The power change is compared with a preset change threshold. If the power change is greater than the preset change threshold, the current control mode is determined to meet the first switching condition for switching from open-loop control mode to closed-loop control mode.

7. The method according to claim 1, characterized in that, The switching transistor that drives the voltage conversion circuit with a fixed frequency and a fixed duty cycle includes: The switching transistor of the voltage conversion circuit is driven according to the maximum duty cycle value and the third frequency value corresponding to the voltage conversion circuit; wherein the third frequency value is less than the fourth frequency value corresponding to the voltage conversion circuit, and the fourth frequency value is used to characterize the preset switching frequency of the voltage conversion circuit; the first frequency value is greater than or equal to the fourth frequency value.

8. The method according to claim 1, characterized in that, The voltage conversion circuit is a Buck circuit, and when there are multiple Buck circuits, the output terminals of the multiple Buck circuits are connected in series.

9. The method according to claim 8, characterized in that, The inverter system includes an inverter, which includes at least one of the Buck circuits and the inverter circuit.

10. The method according to claim 8, characterized in that, The inverter system includes at least one optimizer and an inverter. The optimizer includes at least one Buck circuit, and the inverter is the inverter circuit. The input terminal of the inverter is connected to the output terminal of the optimizer, and when there are multiple optimizers, the output terminals of the multiple optimizers are connected in series.

11. An electronic device, characterized in that, include: At least one processor; as well as A memory communicatively connected to the at least one processor; wherein, The memory stores one or more computer programs that can be executed by the at least one processor, the one or more computer programs being executed by the at least one processor to enable the at least one processor to perform the control method of the inverter system as described in any one of claims 1-10.

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