A control method and control device for current sharing of inductors of an interleaved parallel inverter

Abstract

The present application relates to the field of interleaved parallel inverter, and discloses a control method and a control device for inductance current equalization of an interleaved parallel inverter.The control method for inductance current equalization of the interleaved parallel inverter comprises: collecting inductance currents of a first branch and a second branch of the interleaved parallel inverter respectively, and determining inductance current deviations of the first branch and the second branch; determining a droop modulation wave according to the inductance current deviations and a droop control algorithm of the modulation wave; and adjusting the modulation wave of the first branch or the second branch in real time according to the droop modulation wave and the inductance current deviations, so as to realize inductance current equalization of the first branch and the second branch of the interleaved parallel inverter.Thus, the inductance current equalization of the two branches is realized by optimizing the modulation wave of the first branch and the second branch of the interleaved parallel inverter, and the problem of uneven inductance current of the existing interleaved parallel inverter is solved.

Description

Technical Field

[0001] This invention relates to the field of interleaved parallel inverters, and more particularly to a control method and control device for controlling the inductor current sharing in an interleaved parallel inverter. Background Technology

[0002] In the field of interleaved parallel inverters, inverters expand their capacity by connecting multiple transistors in parallel. Simultaneously, the application of interleaved parallel technology effectively reduces output current ripple and current stress on switching devices, decreases the capacity of individual output filter inductors, reduces bus ripple and the number of bus capacitors, and decreases filter size, thereby improving the output waveform quality of the inverter circuit. Interleaved parallel technology uses the same modulation wave, achieving alternating conduction of switching devices in parallel branches through a 180° carrier wave interleaving. This results in a 180° interleaving of output inductor currents, which are the superposition of inductor currents, thus reducing output ripple. However, differences in switching devices, circuit design, and inductance can lead to uneven current distribution between the two interleaved parallel branches. The branch with the larger current not only generates more heat but also increases the stress on the switching devices, thus affecting the inverter's stability and lifespan.

[0003] In industrial applications, the current distribution of inductors is usually ensured as much as possible by screening the inductance and selecting switching devices, but this method will greatly increase production costs. Summary of the Invention

[0004] The present invention aims to provide a control method and control device for controlling the current sharing of inductor current in an interleaved parallel inverter, which can solve the problem of uneven current sharing of inductor current in existing interleaved parallel inverters.

[0005] To address the aforementioned technical problems, the first aspect of this invention provides a control method for current sharing inductor current in an interleaved parallel inverter, applied to an interleaved parallel inverter, wherein the interleaved parallel inverter includes a first branch and a second branch; the control method includes:

[0006] The inductor currents of the first branch and the second branch of the interleaved parallel inverter are collected respectively to determine the inductor current deviation between the first branch and the second branch.

[0007] The drooping modulation wave is determined based on the inductor current deviation and the modulation wave droop control algorithm.

[0008] Based on the drooping modulation wave and the inductor current deviation, the modulation wave of the first branch or the second branch is adjusted in real time to achieve current sharing of the inductor current in the first branch and the second branch.

[0009] Optionally, the step of separately collecting the inductor currents of the first branch and the second branch of the interleaved parallel inverter, and determining the inductor current deviation between the first branch and the second branch, includes:

[0010] The inductor currents of the first branch and the second branch of the interleaved parallel inverter are collected respectively to determine the effective values ​​of the inductor currents of the first branch and the second branch.

[0011] The inductor current deviation is determined based on the effective value and sign function of the inductor current.

[0012] Optionally, determining the inductor current deviation based on the effective value and sign function of the inductor current includes: determining the sign function based on the product of the output port voltage and current, and then multiplying the sign function by the difference between the effective values ​​of the inductor currents of the first branch and the second branch to obtain the inductor current deviation. .

[0013] Optionally, determining the droop modulation wave based on the inductor current deviation and the modulation wave droop control algorithm includes:

[0014] The modulation wave adjustment amount is determined based on the inductor current deviation and the modulation wave droop control algorithm.

[0015] The drooping modulation wave is determined based on the modulation wave adjustment amount.

[0016] Optionally, determining the modulation wave adjustment amount based on the inductor current deviation and the modulation wave droop control algorithm includes: determining the modulation wave adjustment amount using the following formula:

[0017]

[0018] In the formula, This is the drooping ratio coefficient. The droop integral coefficient is... This is the modulation wave adjustment amount.

[0019] Optionally, determining the droop modulation wave based on the modulation wave adjustment amount includes: determining the droop modulation wave using the following formula:

[0020]

[0021] In the formula, It is a droop-modulated wave. The modulation wave for real-time control of interleaved parallel inverters. i Branch numbering for interleaved parallel inverters This is the modulation wave adjustment amount.

[0022] Optionally, adjusting the modulation wave of the first branch or the second branch in real time based on the drooping modulation wave and the inductor current deviation includes:

[0023] When the inductor current deviation is greater than 0, the first branch activates droop control, and the modulation wave of the first branch is... The second branch remains unchanged, and the modulated wave of the second branch is ;

[0024] When the inductor current deviation is less than 0, the second branch activates droop control, and the modulation wave of the second branch is... The first branch remains unchanged, and the modulated wave of the first branch is ;

[0025] in, The modulation wave for real-time control of interleaved parallel inverters. This is the modulation wave adjustment amount.

[0026] Accordingly, a second aspect of the present invention also provides a control device for the current sharing of inductor current in an interleaved parallel inverter, the interleaved parallel inverter including a first branch and a second branch, the control device including a memory, a controller and a computer program stored in the memory and executable on the controller, the computer program being executed by the controller to implement the steps of the control method for the current sharing of inductor current in an interleaved parallel inverter as described in the first aspect.

[0027] Compared with existing technologies, this invention provides a control method and device for controlling inductor current sharing in interleaved parallel inverters. This inductor current sharing control method for interleaved parallel inverters collects the inductor currents of the first and second branches of the interleaved parallel inverter, determines the inductor current deviation between the first and second branches, and then determines the droop modulation wave based on the inductor current deviation and a modulation wave droop control algorithm. Based on the droop modulation wave and the inductor current deviation, the modulation wave of the first or second branch is adjusted in real time. This optimizes the modulation waves of the first and second branches of the interleaved parallel inverter to achieve inductor current sharing between the two branches, solving the problem of uneven inductor current in existing interleaved parallel inverters. Attached Figure Description

[0028] 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.

[0029] Figure 1 This is a flowchart illustrating a control method for current sharing in an interleaved parallel inverter provided by the present invention.

[0030] Figure 2 This is a schematic diagram of the structure of a control device for sharing the inductor current of an interleaved parallel inverter provided by the present invention;

[0031] Figure 3 This is a schematic diagram of the topology of an interleaved parallel single-phase T-type three-level inverter provided by the present invention;

[0032] Figure 4 This is a schematic diagram of the operating voltage and current of an interleaved parallel single-phase T-type three-level inverter provided by the present invention;

[0033] Figure 5 This is a schematic diagram of the inverter current sharing modulation principle provided by the present invention, which is a control method for current sharing of inductor current in an interleaved parallel inverter. Detailed Implementation

[0034] To facilitate understanding of the present invention, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as being "connected" to another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "upper," "lower," "inner," "outer," "bottom," etc., used in this specification indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0036] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] In one embodiment, such as Figure 1As shown, this invention provides a control method for inductor current sharing in an interleaved parallel inverter, applicable to an interleaved parallel inverter including a first branch and a second branch. The control method includes:

[0038] S1. Collect the inductor current of the first branch and the second branch of the interleaved parallel inverter respectively, and determine the inductor current deviation between the first branch and the second branch.

[0039] S2. Determine the droop modulation wave based on the inductor current deviation and the modulation wave droop control algorithm;

[0040] S3. Based on the droop modulation wave and the inductor current deviation, adjust the modulation wave of the first or second branch in real time to achieve current sharing of the inductor current in the first and second branches of the interleaved parallel inverter.

[0041] In practical applications, the modulation waves of the two sets of inverters in an interleaved parallel inverter are the same, with carrier waves interleaved by 180°. Therefore, the drive pulse widths generated by the drive waves have the same duty cycle but a phase difference of 180°. For an interleaved parallel inverter, when the output current is constant, controlling the increase or decrease of the inductor current in one branch will inevitably lead to a decrease or increase in the inductor current in the other branch. Therefore, this embodiment provides a control method for current sharing of inductor current in an interleaved parallel inverter. By separately collecting the inductor currents of the first and second branches of the interleaved parallel inverter, the inductor current deviation between the first and second branches is determined. Then, a drooping modulation wave is determined based on the inductor current deviation and the modulation wave droop control algorithm. Based on the drooping modulation wave and the inductor current deviation, the modulation wave of the first or second branch is adjusted in real time. Thus, by optimizing the modulation waves of the first and second branches of the interleaved parallel inverter, current sharing of the inductor current in the two branches is achieved, solving the problem of uneven current sharing of inductor current in existing interleaved parallel inverters.

[0042] In one embodiment, in step S1, the inductor currents of the first branch and the second branch of the interleaved parallel inverter are collected respectively, and the inductor current deviation between the first branch and the second branch is determined, specifically including:

[0043] S11. Collect the inductor current of the first branch and the second branch of the interleaved parallel inverter respectively, and determine the effective value of the inductor current of the first branch and the second branch.

[0044] Specifically, the interleaved parallel inverter includes a first branch and a second branch.

[0045] For example, such as Figure 3The interleaved parallel single-phase T-type three-level inverter shown includes a first branch and a second branch, with identical topologies. The first branch consists of a first capacitor C1, a first switching device S11, a second switching device S12, a third switching device S13, a fourth switching device S14, a second capacitor C2, and a first inductor L1. The output terminal of the first switching device S11 is connected to the first inductor L1 and serves as the output terminal of the first branch. The second branch consists of a first capacitor C1, a fifth switching device S21, a sixth switching device S22, a seventh switching device S23, an eighth switching device S24, a second capacitor C2, and a second inductor L2. The output terminal of the fifth switching device S21 is connected to the second inductor L2 and serves as the output terminal of the second branch.

[0046] Collect the inductor current of the first branch of the interleaved parallel inverter. Inductor current of the second branch Optionally, current sensors are used to collect the inductor current of the first branch of the interleaved inverter. Inductor current of the second branch Alternatively, other methods may be used for current acquisition. This embodiment does not limit the specific current acquisition method.

[0047] In practical applications, the modulation waves of the two inverters in an interleaved parallel inverter are the same, with the carrier waves interleaved by 180°. Therefore, the drive pulse widths generated by the drive waves have the same duty cycle but a 180° phase difference. For an interleaved parallel inverter, when the output current is constant, increasing or decreasing the inductor current of one branch will inevitably lead to a decrease or increase in the inductor current of the other branch. Therefore, it is necessary to separately collect the inductor currents of the two branches of the interleaved parallel inverter. and This is to determine the magnitude of the inductor current in the two branches.

[0048] Based on the inductor currents of the two branches and inductor current Determine the effective values ​​of the inductor currents in the two branches. and Specifically, it includes:

[0049] Based on the inductor currents of the two branches and inductor current Since the inductor current waveform is a periodic function, let the inductor current waveform function be f(t). The controller uses the following definite integral formula (1) to calculate the effective value of the inductor current in one cycle, and then the effective values ​​of the inductor current in both branches can be calculated. and :

[0050] (1)

[0051] Where T is the period of the inductor current waveform. i The branch numbers (1,2) are for the interleaved parallel inverters.

[0052] In this embodiment, by separately collecting the inductor currents of the two branches of the interleaved parallel inverter, and combining the inductor current waveform function and definite integral formula, the effective value of the inductor current of the two branches is determined, thereby obtaining a more accurate inductor current value for the two branches.

[0053] S12. Determine the inductor current deviation based on the effective value and sign function of the inductor current in the first branch and the second branch.

[0054] Specifically, the sign function is determined based on the product of the output port voltage and current, and then the sign function is multiplied by the difference between the effective values ​​of the inductor currents of the first branch and the second branch to obtain the inductor current deviation. More specifically, in obtaining the effective values ​​of the inductor currents of the two branches... and Subsequently, the controller uses a sign function to further determine the inductor current deviation. As shown in the following formula (2):

[0055] (2)

[0056] In formula (2), Define the output current as a sign function. With output port voltage Positive directions are those in the same direction, and negative directions are those in opposite directions.

[0057] In this embodiment, by using the sign function and the effective value of the inductor current of the two branches, a more accurate inductor current deviation can be obtained. This means that the current deviation can be obtained when the output voltage and current are in the same direction, and the inductor current deviation can be obtained when the output voltage and current are in opposite directions.

[0058] In one embodiment, in step S2, the drooping modulation wave is determined based on the inductor current deviation and the modulation wave droop control algorithm; specifically, this includes:

[0059] S21. Determine the modulation wave adjustment amount based on the inductor current deviation and the modulation wave droop control algorithm.

[0060] Specifically, in obtaining the inductor current deviation Subsequently, the controller uses a modulation wave droop control algorithm to further determine the modulation wave adjustment amount. As shown in the following formula (3):

[0061] (3)

[0062] In formula (3), This is the drooping ratio coefficient. The droop integral coefficient is... This is the adjustment amount of the modulated wave after the droop coefficient has been adjusted.

[0063] By processing the inductor current deviation using a modulation wave droop control algorithm, an accurate modulation wave adjustment amount can be obtained, providing a more accurate modulation wave adjustment amount for subsequent determination of the droop modulation wave.

[0064] S22. Determine the drooping modulation wave based on the modulation wave adjustment amount.

[0065] Specifically, in determining the modulation wave adjustment amount Subsequently, the controller further determines the drooping modulation wave. As shown in the following formula (4):

[0066] (4)

[0067] The modulation wave for real-time control of interleaved parallel inverters. i The branch numbers are for the interleaved parallel inverters (the first branch is numbered 1, and the second branch is numbered 2).

[0068] In one embodiment, in step S3, the modulation wave of the first branch or the second branch is adjusted in real time according to the droop modulation wave and the inductor current deviation, so as to achieve equal current of the inductor current of the first branch and the second branch of the interleaved parallel inverter.

[0069] Specifically, the controller adjusts the modulation wave of the first or second branch in real time based on the droop modulation wave and the inductor current deviation, including:

[0070] When the inductor current deviates At that time, droop control is activated in the first branch, and the modulation waveform of the first branch is... The second branch remains unchanged, and the modulated wave of the second branch is ;

[0071] When the inductor current deviates At that time, the second branch activates droop control, and the modulation waveform of the second branch is... The first branch remains unchanged, and the modulated wave of the first branch is .

[0072] Therefore, based on the magnitude of the inductor current in the two branches of the interleaved parallel inverter, the modulation waves of the first and second branches can be adjusted in real time using a modulation wave droop control algorithm to ensure that the inductor current in the two branches of the interleaved parallel inverter is equalized.

[0073] Based on the same concept, in one embodiment, such as Figure 2 As shown, the present invention also provides a control device 100 for inductor current sharing in an interleaved parallel inverter. The interleaved parallel inverter includes a first branch and a second branch. The control device 100 includes a memory 10, a controller 20, and a computer program stored in the memory 10 and executable on the controller 20. When the computer program is executed by the controller 20, it implements the steps of the control method for inductor current sharing in an interleaved parallel inverter as described in any of the above embodiments.

[0074] This embodiment provides a control device for equalizing inductor current in an interleaved parallel inverter. It collects the inductor currents of the first and second branches of the interleaved parallel inverter, determines the inductor current deviation between the two branches, and then determines a drooping modulation wave based on the inductor current deviation and a modulation wave droop control algorithm. Based on the drooping modulation wave and the inductor current deviation, it adjusts the modulation wave of either the first or second branch in real time. This optimizes the modulation waves of the first and second branches of the interleaved parallel inverter to achieve equalization of inductor current in the two branches, thus solving the problem of uneven inductor current in existing interleaved parallel inverters.

[0075] It should be noted that the above-described control device embodiment for the current sharing of interleaved parallel inverter inductors and the control method embodiment for the current sharing of interleaved parallel inverter inductors belong to the same concept. For details of the specific implementation process, please refer to the control method embodiment for the current sharing of interleaved parallel inverter inductors. Furthermore, the technical features of the control method embodiment for the current sharing of interleaved parallel inverter inductors are all applicable to the above-described control device embodiment for the current sharing of interleaved parallel inverter inductors, and will not be repeated here.

[0076] To facilitate understanding of the above-mentioned inventive concept of the present invention, the above-mentioned inventive concept of the present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments.

[0077] Taking an interleaved parallel single-phase T-type three-level inverter as an example, the present invention will provide a more detailed description of a control method for inductor current sharing in an interleaved parallel inverter.

[0078] like Figure 3 The diagram shows the structure of an interleaved parallel single-phase T-type three-level inverter.

[0079] exist Figure 3 In this circuit, an interleaved parallel single-phase T-type three-level inverter is used to convert DC power (VDC) into grid-connected single-phase AC power. Its output port voltage is... .in:

[0080] The DC power supply VDC provides DC power to the entire inverter. The DC side is divided into two equal voltage sections by the first capacitor C1 and the second capacitor C2. Point N is the connection point of the first capacitor C1 and the second capacitor C2, which is also the "middle potential point" of the three-level output, realizing the three-level output.

[0081] Eight switching devices (first switching device S11, second switching device S12, third switching device S13, fourth switching device S14, fifth switching device S21, sixth switching device S22, seventh switching device S23, and eighth switching device S24) form an inverter bridge. Among them, the first switching device S11, second switching device S12, third switching device S13, and fourth switching device S14 are the first bridge arms, and the fifth switching device S21, sixth switching device S22, seventh switching device S23, and eighth switching device S24 are the second bridge arms. The output terminals of the first and second bridge arms are connected in parallel, so that the inverter constitutes an interleaved parallel inverter.

[0082] The first capacitor C1, the first switching device S11, the second switching device S12, the third switching device S13, the fourth switching device S14, the second capacitor C2, and the first inductor L1 constitute the first branch. The output terminal of the first switching device S11 is connected to the first inductor L1 and serves as the output terminal of the first branch.

[0083] The first capacitor C1, the fifth switch S21, the sixth switch S22, the seventh switch S23, the eighth switch S24, the second capacitor C2, and the second inductor L2 constitute the second branch. The output terminal of the fifth switch S21 is connected to the second inductor L2 and serves as the output terminal of the second branch.

[0084] The first inductor L1 and the second inductor L2 are AC filter inductors on the output side of the inverter, used to filter out high-frequency harmonics in the inverter output, making the output current closer to a sine wave, and further reducing current ripple by interleaving them in parallel.

[0085] The grid-side inductor Lf is located on the grid side and is used to suppress high-frequency circulating current between the inverter and the grid, ensuring the stability of the grid-connected current and power quality, while also playing a certain filtering role.

[0086] The AC filter capacitor Cf is located on the grid side, forming an LC filter network with the grid-side inductor Lf to further filter out high-order harmonics, while also playing a role in stabilizing the voltage.

[0087] Output port voltage on the grid side It is a sinusoidal AC voltage source, indicating that the inverter's output will eventually be connected to this power grid.

[0088] The interleaved parallel single-phase T-type three-level inverter of this invention can be applied to the field of power quality improvement, such as harmonic compensators (APF) and static var generators (SVG), or in the field of energy storage, such as energy storage converters (PCS). While pursuing high efficiency, low harmonics, and high power, the advantages of the T-type three-level inverter can be utilized to reduce switching losses and device stress, and the interleaved parallel connection further improves current capacity and power quality.

[0089] like Figure 4 The diagram shows the working voltage and current of an interleaved parallel single-phase T-type three-level inverter operating in four quadrants. Figure 4 In the diagram, Mode 1 indicates the output current. With output port voltage Same direction, Mode 2 indicates output current With output port voltage Reverse. Collect the inductor current of the first branch of the interleaved parallel inverter. The inductor current in the second branch .

[0090] The current sharing control adjustment methods for interleaved parallel single-phase T-type three-level inverters operating in different operating regions are as follows:

[0091] In operating region 1, the second switch S12 and the sixth switch S22 are normally closed, the fourth switch S14 and the eighth switch S24 are normally open, the first switch S11 and the third switch S13 are alternately conducting, and the fifth switch S21 and the seventh switch S23 are alternately conducting. Current flows from the grid to the inverter, and the inverter operates in mode 2. Therefore, the inductor current deviation... Due to inductor current deviation The first branch activates droop control, and the modulated wave is... The second branch remains unchanged, modulated wave ,like Figure 5 As shown. In the first branch, because the modulation amplitude decreases, the pulse width of the first switching device S11 decreases; correspondingly, the pulse width of the third switching device S13 increases, as shown. Figure 5 As shown, the dashed box represents the drive signal before adjustment by the third switching device S13, and the solid box represents the drive signal after adjustment. It can be seen that the increased pulse width of the third switching device S13 increases the inductor current of the first branch in this region. The charging time increases, which in turn increases the inductor current in the first branch. As the modulation wave increases, it will adjust in real time according to the output current. Further control based on the droop of the modulation wave will eventually make the inductor currents of the first and second branches tend to be equal.

[0092] In operating region 2, the second switch S12 and the sixth switch S22 are normally closed, the fourth switch S14 and the eighth switch S24 are normally open, the first switch S11 and the third switch S13 are alternately conducting, and the fifth switch S21 and the seventh switch S23 are alternately conducting. Current flows from the inverter to the grid. The inverter is operating in mode 1, so the inductor current deviation... Due to inductor current deviation The second branch activates droop control, and the modulated wave is... The first branch remains unchanged, modulated wave ,like Figure 4 As shown. Because the modulation amplitude decreases in the second branch, the pulse width of the fifth switching device S21 decreases, while the pulse width of the seventh switching device S23 increases. The decrease in the pulse width of the fifth switching device S21 reduces the inductor current in the second branch within this region. The charging time is reduced, which in turn reduces the inductor current in the second branch. The modulation wave is adjusted in real time according to the output current, and further controlled by the droop of the modulation wave, the inductor current of the first branch is reduced. It will increase, eventually causing the inductor currents in the first and second branches to tend to be equal.

[0093] In operating region 3, the third switch S13 and the seventh switch S23 are normally closed, the first switch S11 and the fifth switch S21 are normally open, the second switch S12 and the fourth switch S14 are alternately turned on, and the sixth switch S22 and the eighth switch S24 are alternately turned on. Current flows from the inverter to the grid. The inverter is operating in mode 2, so the inductor current deviation... Due to inductor current deviation The first branch activates droop control, and the modulated wave is... The second branch remains unchanged, modulated wave ,like Figure 4 As shown, in the first branch, due to the decrease in modulation amplitude, the pulse width of the fourth switching device S14 decreases, while the pulse width of the second switching device S12 increases. This increase in the pulse width of the second switching device S12 leads to a decrease in the inductor current of the first branch in that region. The charging time increases, which in turn increases the inductor current in the first branch. The inductor current in the second branch increases because the modulation wave adjusts in real time according to the output current. Further droop control based on the modulation wave further increases the inductor current. This will decrease, eventually causing the inductor currents in the first and second branches to tend to be equal.

[0094] In operating region 4, the third switch S13 and the seventh switch S23 are normally closed, the first switch S11 and the fifth switch S21 are normally open, the second switch S12 and the fourth switch S14 are alternately conducting, and the sixth switch S22 and the eighth switch S24 are alternately conducting. Current flows from the grid to the inverter. The inverter is operating in mode 1, so the inductor current deviation... Due to inductor current deviation The second branch activates droop control, and the modulated wave is... ,like Figure 4 As shown. The first branch remains unchanged, modulated wave Because the modulation amplitude decreases in the second branch, the pulse width of the eighth switching device S24 decreases, while the pulse width of the sixth switching device S22 increases. The decrease in the pulse width of the eighth switching device S24 reduces the inductor current in the second branch within this region. The charging time is reduced, which in turn reduces the inductor current in the second branch. The inductor current in the first branch is reduced because the modulation wave is adjusted in real time according to the output current. Further droop control based on the modulation wave reduces this effect. It will increase, eventually causing the inductor currents in the first and second branches to tend to be equal.

[0095] In summary, this invention achieves current sharing between the inductor currents of the first and second branches of an interleaved parallel inverter by adjusting the inductor current difference between the first and second branches and determining the branch requiring adjustment based on both the output voltage and current direction. This optimization of the modulation waveforms of the first and second branches of the interleaved parallel inverter, along with the coverage of all operating modes of the inverter, solves the problem of uneven inductor current in existing interleaved parallel inverters.

[0096] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0097] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Under the concept of the present invention, 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 the present invention as described above. For the sake of brevity, they are not provided in detail. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. 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 the present invention.

Claims

1. A control method for current sharing of inductor current in an interleaved parallel inverter, characterized in that, The method is applied to an interleaved parallel inverter, which includes a first branch and a second branch; the control method includes: The inductor currents of the first branch and the second branch of the interleaved parallel inverter are collected respectively to determine the inductor current deviation between the first branch and the second branch. The drooping modulation wave is determined based on the inductor current deviation and the modulation wave droop control algorithm. Based on the drooping modulation wave and the inductor current deviation, the modulation wave of the first branch or the second branch is adjusted in real time to achieve current sharing of the inductor current in the first branch and the second branch. The step of separately collecting the inductor currents of the first branch and the second branch of the interleaved parallel inverter, and determining the inductor current deviation between the first branch and the second branch, includes: The inductor currents of the first branch and the second branch of the interleaved parallel inverter are collected respectively to determine the effective values ​​of the inductor currents of the first branch and the second branch. The inductor current deviation is determined based on the effective value and sign function of the inductor current; The step of determining the inductor current deviation based on the effective value and sign function of the inductor current includes: The sign function is determined based on the product of the output port voltage and current. The output current is defined as positive if its direction is the same as the output port voltage, and negative if their directions are opposite. The sign function is then multiplied by the difference between the effective values ​​of the inductor currents in the first and second branches to obtain the inductor current deviation. .

2. The control method according to claim 1, characterized in that, The step of determining the droop modulation wave based on the inductor current deviation and the modulation wave droop control algorithm includes: The modulation wave adjustment amount is determined based on the inductor current deviation and the modulation wave droop control algorithm. The drooping modulation wave is determined based on the modulation wave adjustment amount.

3. The control method according to claim 2, characterized in that, The step of determining the modulation wave adjustment amount based on the inductor current deviation and the modulation wave droop control algorithm includes: determining the modulation wave adjustment amount using the following formula: ； In the formula, This is the drooping ratio coefficient. The droop integral coefficient is... This is the modulation wave adjustment amount.

4. The control method according to claim 3, characterized in that, The step of determining the droop modulation wave based on the modulation wave adjustment amount includes: determining the droop modulation wave using the following formula: ； In the formula, It is a droop-modulated wave. The modulation wave for real-time control of interleaved parallel inverters. Branch numbering for interleaved parallel inverters This is the modulation wave adjustment amount.

5. The control method according to claim 4, characterized in that, The step of adjusting the modulation wave of the first branch or the second branch in real time based on the drooping modulation wave and the inductor current deviation includes: When the inductor current deviation is greater than 0, the first branch activates droop control, and the modulation wave of the first branch is... The second branch remains unchanged, and the modulated wave of the second branch is ; When the inductor current deviation is less than 0, the second branch activates droop control, and the modulation wave of the second branch is... The first branch remains unchanged, and the modulated wave of the first branch is ; in, The modulation wave for real-time control of interleaved parallel inverters. This is the modulation wave adjustment amount.

6. A control device for current sharing of inductor current in an interleaved parallel inverter, characterized in that, The interleaved parallel inverter includes a first branch and a second branch. The control device includes a memory, a controller, and a computer program stored in the memory and executable on the controller. When the computer program is executed by the controller, it implements the steps of the control method for sharing inductor current as described in any one of claims 1 to 5.

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