Method of suppressing a double frequency ripple in an inverter input current and inverter

Abstract

This application relates to the field of microgrid technology, and in particular to a method, inverter, and storage medium for suppressing second-harmonic ripple in the input current of an inverter. The method includes: acquiring the output voltage and output current of the inverter and calculating the instantaneous output power; extracting the second-harmonic pulsating power component from the instantaneous output power; determining a calculation model for the current compensation term to perform feedforward compensation on the input current of the preceding DC-DC converter based on the circuit model of the preceding DC-DC converter; synthesizing the output signal of the voltage control outer loop of the preceding DC-DC converter and the current compensation signal calculated based on the calculation model of the current compensation term to obtain a total input current reference value; and performing current inner loop control on the preceding DC-DC converter based on the total input current reference value. The method of this application directly addresses the disturbance source through feedforward compensation, exhibiting fast dynamic response and significant suppression effect on second-harmonic ripple.

Description

Technical Field

[0001] This application relates to the field of microgrid technology, and in particular to a method for suppressing second harmonic ripple in inverter input current, an inverter, and a storage medium. Background Technology

[0002] Two-stage single-phase inverters are widely used in photovoltaic energy storage, uninterruptible power supplies (UPS), and microgrids. Their typical architecture consists of a front-stage DC-DC converter and a rear-stage single-phase DC-AC inverter cascaded together. The front-stage DC-DC converter performs voltage matching and initial voltage regulation, boosting or converting the DC voltage from the input source (such as batteries or photovoltaic panels) to a stable DC bus voltage. The rear-stage single-phase DC-AC inverter then uses pulse width modulation (PWM) technology to invert the DC bus voltage into single-phase AC power of the required frequency and amplitude.

[0003] However, the instantaneous output power of a single-phase inverter is not constant. According to the principles of AC circuits, its instantaneous output power contains a DC component and an AC component that pulsates at twice the frequency of the output voltage, i.e., a second-harmonic pulsating power component. In an ideal lossless system, according to the principle of power conservation, this second-harmonic pulsating power component will inevitably be transmitted from the downstream single-phase DC-AC inverter to the upstream stage, causing a ripple current of the corresponding frequency in the input current of the upstream DC-DC converter, i.e., an input current second-harmonic ripple.

[0004] The ripple current has significant harmful effects on the system: 1) For input sources, such as batteries, low-frequency high-current ripple will accelerate the internal chemical reaction, cause additional heat generation, and significantly shorten the cycle life; 2) For the front-end converter, it increases the current stress and conduction loss of power devices such as switching transistors and inductors, reducing the overall system efficiency; 3) It may cause electromagnetic compatibility problems.

[0005] Traditional solutions are mainly divided into two categories: hardware decoupling and software suppression. Hardware solutions, such as adding passive filter capacitors or active power decoupling circuits, are effective but increase system size, cost, and complexity. Software solutions focus more on optimizing the control loop of the front-end DC-DC converter, such as by improving the parameters of the voltage or current controller to enhance the suppression of low-frequency disturbances. However, such methods usually have limited response speed and may affect the dynamic performance of the system.

[0006] Therefore, there is an urgent need for a control method that can accurately and quickly counteract second harmonic power disturbances without increasing hardware costs. Summary of the Invention

[0007] The embodiments of this application aim to provide a method, inverter, and storage medium for suppressing second harmonic ripple in the input current of an inverter, thereby solving the technical problems of poor suppression effect and high cost of second harmonic ripple in the input current of two-stage single-phase inverters in the prior art.

[0008] To address the aforementioned technical problems, this application provides the following technical solutions:

[0009] According to a first aspect of this application, a method for suppressing second-harmonic ripple in the input current of an inverter is provided, the inverter comprising a front-stage DC-DC converter and a rear-stage single-phase DC-AC inverter, the method comprising:

[0010] The output voltage and output current of the inverter are collected, and the instantaneous output power is calculated.

[0011] Extract the second harmonic pulsating power component from the instantaneous output power;

[0012] Based on the circuit model of the preceding DC-DC converter, a calculation model for the current compensation term that performs feedforward compensation on the input current of the preceding DC-DC converter is determined. The current compensation term is used to offset the disturbance effect of the second harmonic pulsating power component on the input current.

[0013] The output signal of the voltage control outer loop of the front-end DC-DC converter and the current compensation signal calculated based on the calculation model of the current compensation term are combined to obtain the total input current reference value.

[0014] The upstream DC-DC converter is subjected to current inner-loop control based on the total input current reference value.

[0015] Optionally, extracting the second harmonic pulsating power component from the instantaneous output power includes:

[0016] A second-order generalized integrator is used to extract the second harmonic pulsating power component from the instantaneous output power.

[0017] Optionally, the transfer function of the second-order generalized integrator is:

[0018]

[0019] in, s Let Laplace be the complex frequency variable. The characteristic frequency is The transfer function of the second-order generalized integrator. This is the SOGI gain coefficient. The fundamental frequency of the inverter's output voltage. ω The characteristic angular frequency, .

[0020] Optionally, the front-stage DC-DC converter is a Boost converter, which includes a DC voltage input source, a switching transistor, an input inductor, a diode, and a bus capacitor. Based on the circuit model of the front-stage DC-DC converter, the calculation model for the current compensation term of the input current of the front-stage DC-DC converter includes:

[0021] Based on the first assumption model that the second harmonic pulsating power component is completely absorbed or completely released by the bus capacitor, the first relationship between the second harmonic pulsating voltage component and the second harmonic pulsating power component in the bus capacitor voltage is determined.

[0022] Based on the second assumption model that the second harmonic pulsating power component is completely absorbed or completely released by the input inductor and the first relational expression, the second relational expression between the second harmonic pulsating current component and the second harmonic pulsating power component in the input current is determined;

[0023] The second harmonic pulsating current component in the input current is used as the current compensation term to obtain the calculation model of the current compensation term.

[0024] Optionally, the first relation is:

[0025]

[0026] in, This refers to the second harmonic pulsating voltage component in the bus capacitor voltage. This refers to the second harmonic pulsating power component. The fundamental angular frequency, , The fundamental frequency of the inverter's output voltage. The capacitance value of the bus capacitor. This is a reference value for the bus voltage. s Let Laplace be the complex frequency variable. , This is the 90-degree right shift operator for the second harmonic pulsating power component.

[0027] Optionally, the calculation model for the current compensation term is as follows:

[0028]

[0029] in, For the current compensation term, The inductance value of the input inductor.

[0030] Optionally, the step of synthesizing the output signal of the voltage control outer loop of the preceding DC-DC converter and the current compensation signal calculated based on the calculation model of the current compensation term to obtain the total input current reference value is specifically as follows:

[0031] The total input current reference value is obtained by subtracting the current compensation signal calculated based on the calculation model of the current compensation term from the output signal of the voltage control outer loop of the front-stage DC-DC converter.

[0032] According to a second aspect of this application, a two-stage single-phase inverter is provided, the two-stage single-phase inverter comprising a front-stage DC-DC converter, a rear-stage single-phase DC-AC inverter, and a controller, the controller comprising: at least one processor and a memory communicatively connected to the at least one processor, the memory storing instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform any of the methods described above, where the front-stage DC-DC converter is not limited to a Boost converter.

[0033] According to a third aspect of this application, a two-stage single-phase inverter is provided, the two-stage single-phase inverter comprising a front-stage DC-DC converter, a rear-stage single-phase DC-AC inverter, and a controller, wherein the front-stage DC-DC converter is a Boost converter, the Boost converter comprising a DC voltage input source, a switching transistor, an input inductor, a diode, and a bus capacitor, and the controller comprising: at least one processor and a memory communicatively connected to the at least one processor, the memory storing instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform any of the methods described above in which the front-stage DC-DC converter is limited to a Boost converter.

[0034] According to a fourth aspect of this application, a computer-readable storage medium is provided, the computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of any of the methods described above.

[0035] The beneficial effects of this application's embodiments are as follows: Unlike existing technologies, this application provides a method for suppressing second-harmonic ripple in the inverter input current. This involves real-time acquisition of the inverter's output voltage and current to calculate the instantaneous output power; extracting the second-harmonic pulsating power component from the instantaneous output power; crucially, designing and calculating a current compensation term for feedforward compensation of the input current of the preceding DC-DC converter based on its specific circuit model; finally, synthesizing this current compensation term with the output signal of the preceding converter's voltage control outer loop to generate a total input current reference value for inner loop control. This proactively and accurately cancels second-harmonic disturbances at the control source, achieving smooth input current. The method of this application directly addresses the disturbance source through feedforward compensation, exhibiting fast dynamic response and significant suppression of second-harmonic ripple; moreover, it is entirely implemented through a control algorithm, requiring no additional power devices or decoupling circuits, thus saving cost and size. Attached Figure Description

[0036] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0037] Figure 1 This is a schematic diagram of the structure of the two-stage inverter provided in the embodiments of this application;

[0038] Figure 2 This is a topology diagram of a two-stage single-phase inverter with a Boost converter as the front-end, provided in an embodiment of this application.

[0039] Figure 3 This is a schematic diagram of the controller provided in an embodiment of this application;

[0040] Figure 4 This is a schematic diagram of the dual closed-loop control strategy of the Boost converter provided in the embodiments of this application;

[0041] Figure 5 This is a flowchart of a method for suppressing second harmonic ripple in the input current of an inverter, provided in an embodiment of this application.

[0042] Figure 6 This is a schematic diagram of a control strategy using a method to suppress second-harmonic ripple in the inverter input current, provided in an embodiment of this application.

[0043] Figure 7 This is a comparison diagram of the control effects before and after inhibition provided in the embodiments of this application. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0045] Furthermore, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0046] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0047] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a two-stage inverter provided in an embodiment of this application. Figure 1 As shown, the two-stage inverter includes a DC voltage input source composed of battery modules. Front-end DC-DC converter, bus capacitor The preceding stage consists of a DC-AC inverter and a controller. The preceding stage DC-DC converter is used to convert the DC voltage input source... The DC voltage is boosted or transformed to a stable DC bus voltage. The subsequent DC-AC inverter uses pulse width modulation technology to adjust the DC bus voltage. It is inverted into single-phase alternating current with the required frequency and amplitude.

[0048] The controller is connected to each switching transistor in both the front-end DC-DC converter and the rear-end DC-AC inverter, and controls the on and off of each switching transistor based on a built-in control program. In some embodiments, the controller may be a microcontroller unit (MCU) or a digital signal processing (DSP) controller, etc.

[0049] In some embodiments, the two-stage inverter may further include an output voltage sampling unit and an output current sampling unit, which are used to collect the output voltage and output current of the two-stage inverter in real time, respectively.

[0050] Please refer to Figure 2 , Figure 2This is a topology diagram of a two-stage single-phase inverter with a Boost converter as the front-end, as provided in an embodiment of this application. Figure 2 As shown, the front-stage DC-DC converter is a Boost converter, and the rear-stage DC-AC inverter is an H4 full-bridge topology. This Boost converter includes a DC voltage input source. Switching transistor Input inductance ,diode and bus capacitor The subsequent DC-AC inverter includes a first switching transistor. Second switching transistor Third switching transistor Fourth switching transistor Filter inductor and filter capacitor The two-stage inverter is connected to the load. .

[0051] Please refer to Figure 3 , Figure 3 An example of a controller structure is shown. Figure 3 As shown, the controller 20 includes at least one processor 21 and a memory 22. The memory 22 can be built into the controller 20 or external to the controller 20. The memory 22 can also be a remotely configured memory connected to the controller 20 via a network.

[0052] Memory 22, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules. Memory 22 may include a program storage area and a data storage area, wherein the program storage area may store the operating system and application programs required for at least one function; the data storage area may store data created based on the use of the terminal, etc. Furthermore, memory 22 may include high-speed random access memory and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, memory 22 may optionally include memory remotely located relative to processor 21, and these remote memories can be connected to the terminal via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0053] The processor 21 performs various functions of the terminal and processes data by running or executing software programs and / or modules stored in the memory 22 and calling data stored in the memory 22, thereby performing overall monitoring of the terminal, such as implementing the method for suppressing second harmonic ripple in the inverter input current as described in any embodiment of this application.

[0054] Processor 21 can be one or more. Figure 2 The example provided is a processor 21. Processor 21 and memory 22 can be connected via a bus or other means. Processor 21 may include a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a controller, a field-programmable gate array (FPGA) device, etc. Processor 21 can also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0055] Please refer to Figure 4 , Figure 4 This is a schematic diagram of the dual closed-loop control strategy of the Boost converter provided in the embodiments of this application. Figure 4 As shown, the bus voltage reference value bus voltage sampling value The difference is then fed into the voltage loop controller. The input current reference value is obtained. Input current reference value With input current sampling value The difference is then fed into the current loop controller. To obtain the duty cycle Generate switching transistor The drive signal. Duty cycle. By transfer function Get the input current Input current By transfer function Obtain the bus voltage .

[0056] Please refer to Figure 5 , Figure 5 This is a flowchart illustrating a method for suppressing second-harmonic ripple in the input current of an inverter, provided in an embodiment of this application. This method is applied to a two-stage single-phase inverter. The two-stage single-phase inverter includes a front-stage DC-DC converter, a rear-stage single-phase DC-AC inverter, and a controller. In some embodiments, the two-stage single-phase inverter can... Figures 1-3 The implementation of the structure is described in detail in the above embodiments and will not be repeated here.

[0057] like Figure 5 As shown, the method for suppressing second-harmonic ripple in the inverter input current includes:

[0058] Step S501: Collect the output voltage and output current of the inverter and calculate the instantaneous output power.

[0059] based on Figure 1 and Figure 2 The two-stage inverter shown can be represented by the following: The output voltage and output current of this inverter can be expressed as follows:

[0060] (1)

[0061] (2)

[0062] in, , , and These are the inverter's output voltage amplitude, output current amplitude, fundamental angular frequency, and load impedance angle, respectively. According to equations (1) and (2), the instantaneous output power of the inverter for:

[0063] (3)

[0064] Furthermore, instantaneous output power It can be written as:

[0065] (4)

[0066] Instantaneous output power Rewritten in the form of superposition of AC and DC components, equation (4) can be written as:

[0067] (5)

[0068] (6)

[0069] (7)

[0070] in, Instantaneous output power DC component in Instantaneous output power The second harmonic pulsating power component in the middle.

[0071] Step S502: Extract the second harmonic pulsating power component from the instantaneous output power.

[0072] As can be seen from equation (4), the instantaneous output power can be calculated based on the output voltage amplitude, output current amplitude, fundamental angular frequency, and load impedance angle. However, obtaining an accurate, fast, and delay-free load impedance angle is quite difficult. One possible approach is to accurately extract the second harmonic pulsating power component from the instantaneous output power using a high-performance filter. For example, the second-order generalized integrator (SOGI) can be used to extract the second harmonic pulsating power component from the instantaneous output power as follows:

[0073] (8)

[0074] (9)

[0075] (10)

[0076] in, The characteristic frequency is The transfer function of the second-order generalized integrator. s Let Laplace be the complex frequency variable. This is the SOGI gain coefficient. This is the fundamental frequency of the output voltage of a two-stage single-phase inverter. ω The characteristic angular frequency is denoted as ω.

[0077] Step S503: Based on the circuit model of the preceding DC-DC converter, determine the calculation model of the current compensation term for feedforward compensation of the input current of the preceding DC-DC converter.

[0078] This current compensation term is used to counteract the disturbance effect of the second harmonic pulsating power component on the input current. The following is an example... Figure 2 The following example of a two-stage inverter will be used to explain in detail the method for determining the calculation model of the current compensation term.

[0079] According to the law of conservation of power, the second-harmonic pulsating power component contained in the instantaneous output power of the downstream DC-AC inverter will inevitably be transmitted to the upstream DC-DC converter. When this second-harmonic pulsating power component is not processed in any way, it is essentially absorbed or released by the bus capacitor. For simplicity, assuming a first model where the second-harmonic pulsating power component is completely absorbed or completely released by the bus capacitor, we have:

[0080] (11)

[0081] in, This is the capacitance value of the bus capacitor. This represents the DC component of the bus capacitor voltage. This refers to the second harmonic pulsating voltage component in the bus capacitor voltage. ω is the fundamental angular frequency.

[0082] Furthermore, integrating both sides of equation (11), we can obtain the first relationship between the second harmonic pulsating voltage component and the second harmonic pulsating power component in the bus capacitor voltage:

[0083] (12)

[0084] (13)

[0085] in, It is a 90-degree right shift operator for the second harmonic pulsating power component.

[0086] In the first assumed model, based on the effect of the outer loop of the Boost converter bus voltage control, the bus voltage is equal to the reference value of the bus voltage:

[0087] (14)

[0088] in, This is the reference value for the bus voltage. Therefore, equation (12) can be rewritten as:

[0089] (15)

[0090] Absorbing or releasing the second-harmonic pulsating power component through the bus capacitor will generate second-harmonic ripple in the input current of the preceding DC-DC converter. Therefore, this application introduces a current compensation term for the input current of the preceding DC-DC converter to counteract the disturbance effect of this second-harmonic pulsating power component on the input current. For example, a second assumption model is presupposed that the second-harmonic pulsating power component is completely absorbed or completely released by the input inductor in the Boost converter. In this second assumption model, based on the conservation of second-harmonic pulsating energy of the input inductor and bus capacitor, we have:

[0091] (16)

[0092] in, The inductance value of the input inductor. Let be the second harmonic pulsating current component in the input current. Substituting equation (15) into equation (16), we can obtain the second relationship between the second harmonic pulsating current component and the second harmonic pulsating power component in the input current:

[0093] (17)

[0094] Furthermore, substituting equation (8) into equation (17), we obtain:

[0095] (18)

[0096] In one embodiment, the second harmonic pulsating current component in the input current is used as the current compensation term of the input current. The calculation model of the current compensation term is shown in equation (18). For a 90-degree right shift operator, The conversion term for bus voltage and input current is obtained by shifting the second harmonic pulsating power component 90 degrees to the right using a right shift operator and dividing it by the conversion term for bus voltage and input current.

[0097] Step S504: Combine the output signal of the voltage control outer loop of the front-end DC-DC converter with the current compensation signal calculated by the calculation model based on the current compensation term to obtain the total input current reference value.

[0098] In one embodiment, the total input current reference value is obtained by subtracting the current compensation signal calculated based on the calculation model of the current compensation term from the output signal of the voltage control outer loop of the preceding DC-DC converter.

[0099] (19)

[0100] in, This is the output signal of the voltage control outer loop of the preceding DC-DC converter. This is the reference value for the total input current.

[0101] Step S505: Perform current inner loop control on the front-end DC-DC converter based on the total input current reference value.

[0102] For example, the difference between the total input current reference value and the input current sample value is sent to the current loop controller for control to obtain the optimized duty cycle. Based on the optimized duty cycle, the switching transistor is driven, which can achieve the suppression of the second harmonic ripple in the input current.

[0103] Please refer to Figure 6 , Figure 6 This is a schematic diagram of a control strategy using a method to suppress second-harmonic ripple in the inverter input current, as provided in an embodiment of this application. Figure 6 As shown, the instantaneous voltage output of the inverter is collected. and instantaneous current And multiply them to obtain the instantaneous output power. Instantaneous output power Through the characteristic frequency is SOGI extracts the second harmonic pulsating power component. ; the second harmonic pulsating power component After shifting 90 degrees to the right by the right shift operator, the current compensation term for the input current is obtained by dividing by the conversion terms of the bus voltage and the input current. ; Current compensation term for input current Output signal of the outer loop of the Boost converter voltage control Synthesize to generate a total input current reference value Implementing inner-loop current control can effectively counteract the impact of second-harmonic power ripple on the input side and suppress second-harmonic ripple in the input current.

[0104] It is understood that the method of this application is also applicable to other DC-DC converters besides Boost converters (such as Buck, Buck-Boost, and various isolated converters). Steps S501, S502, S504, and S505 remain unchanged; the only step that needs adjustment is S503. For different topologies, those skilled in the art can determine the calculation model of the current compensation term corresponding to the circuit model based on its specific circuit structure. When synthesizing the output signal of the voltage control outer loop of the preceding DC-DC converter and the current compensation signal calculated based on the calculation model of the current compensation term, the synthesis method (usually addition or subtraction) needs to be determined according to the specific definition of the current compensation term.

[0105] Please refer to Figure 7 , Figure 7 This is a comparison diagram of the control effects before and after inhibition provided in the embodiments of this application. Figure 7 It is known that without the suppression strategy, the amplitude of the second harmonic ripple current in the input current is about 1.5A~19.6A. However, after adopting the suppression strategy provided in this application, the amplitude of the second harmonic ripple component in the input current becomes 5.8A~15.4A, which is about 53% lower than that without the suppression strategy. The second harmonic current component in the DC side input current is effectively suppressed.

[0106] The method for suppressing second-harmonic ripple in inverter input current provided in this application involves real-time acquisition of the inverter's output voltage and current to calculate the instantaneous output power; extracting the second-harmonic pulsating power component from the instantaneous output power; crucially, designing and calculating a current compensation term for feedforward compensation of the input current of the preceding DC-DC converter based on the specific circuit model of the preceding DC-DC converter; finally, synthesizing this current compensation term with the output signal of the preceding converter's voltage control outer loop to generate a total input current reference value for inner loop control, thereby actively and accurately canceling the second-harmonic disturbance at the control source and achieving smooth input current. This method directly addresses the disturbance source through feedforward compensation, exhibiting fast dynamic response and significant suppression of second-harmonic ripple; moreover, it is entirely implemented through a control algorithm, requiring no additional power devices or decoupling circuits, thus saving cost and size.

[0107] This application also provides a non-volatile computer-readable storage medium storing computer-executable instructions that are executed by one or more processors, for example, to perform the method steps described above.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this application as described above, which are not provided in detail for the sake of brevity; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for suppressing the second harmonic ripple in the input current of an inverter, the inverter comprising a front stage DC-DC converter and a back stage single phase DC-AC inverter, the front stage DC-DC converter being a Boost converter, the Boost converter comprising a DC voltage input source, a switch tube, an input inductor, a diode and a bus capacitor, characterized in that, The method includes: The output voltage and output current of the inverter are collected, and the instantaneous output power is calculated. Extract the second harmonic pulsating power component from the instantaneous output power; Based on the circuit model of the preceding DC-DC converter, a calculation model for the current compensation term that performs feedforward compensation on the input current of the preceding DC-DC converter is determined. The current compensation term is used to offset the disturbance effect of the second harmonic pulsating power component on the input current. The output signal of the voltage control outer loop of the front-end DC-DC converter and the current compensation signal calculated based on the calculation model of the current compensation term are combined to obtain the total input current reference value. The front-end DC-DC converter is subjected to current inner-loop control based on the total input current reference value; The calculation model for the current compensation term is as follows: in, For the current compensation term, The inductance value of the input inductor. This refers to the second harmonic pulsating power component. The fundamental angular frequency, , The fundamental frequency of the inverter's output voltage. The capacitance value of the bus capacitor. This is a reference value for the bus voltage. s Let Laplace be the complex frequency variable. , This is the 90-degree right shift operator for the second harmonic pulsating power component.

2. The method according to claim 1, characterized in that, Extracting the second harmonic pulsating power component from the instantaneous output power includes: A second-order generalized integrator is used to extract the second harmonic pulsating power component from the instantaneous output power.

3. The method according to claim 2, characterized in that, The transfer function of the second-order generalized integrator is: in, The characteristic frequency is The transfer function of the second-order generalized integrator. The gain coefficient of the second-order generalized integrator. ω The characteristic angular frequency, .

4. The method according to any one of claims 1 to 3, characterized in that, The calculation model for determining the current compensation term for feedforward compensation of the input current of the front-stage DC-DC converter, based on the circuit model of the front-stage DC-DC converter, includes: Based on the first assumption model that the second harmonic pulsating power component is completely absorbed or completely released by the bus capacitor, the first relationship between the second harmonic pulsating voltage component and the second harmonic pulsating power component in the bus capacitor voltage is determined. Based on the second assumption model that the second harmonic pulsating power component is completely absorbed or completely released by the input inductor and the first relational expression, the second relational expression between the second harmonic pulsating current component and the second harmonic pulsating power component in the input current is determined; The second harmonic pulsating current component in the input current is used as the current compensation term to obtain the calculation model of the current compensation term.

5. The method according to claim 4, characterized in that, The first relation is: in, This refers to the second harmonic pulsating voltage component in the bus capacitor voltage.

6. The method according to claim 5, characterized in that, The specific steps for synthesizing the output signal of the voltage control outer loop of the front-stage DC-DC converter and the current compensation signal calculated based on the calculation model of the current compensation term to obtain the total input current reference value are as follows: The total input current reference value is obtained by subtracting the current compensation signal calculated based on the calculation model of the current compensation term from the output signal of the voltage control outer loop of the front-stage DC-DC converter.

7. A two-stage single-phase inverter, characterized in that, The two-stage single-phase inverter includes a front-stage DC-DC converter, a rear-stage single-phase DC-AC inverter, and a controller. The front-stage DC-DC converter is a Boost converter, which includes a DC voltage input source, a switching transistor, an input inductor, a diode, and a bus capacitor. The controller includes at least one processor and a memory communicatively connected to the at least one processor. The memory stores instructions executable by the at least one processor, which are executed by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 6.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, performs the steps of the method as described in any one of claims 1-6.

Images