Single-phase inverter circuit and single-phase inverter

Abstract

The application discloses a single-phase inverter circuit and a single-phase inverter, a direct-current source, an inverter bridge comprising a first bridge arm and a second bridge arm, wherein the first bridge arm is connected to the positive and negative poles of the direct-current source respectively, and the second bridge arm is connected to the positive and negative poles of the direct-current source respectively, a bus capacitor connected to the positive and negative poles of the direct-current source respectively, and a filter module, wherein a first input end of the filter module is connected to the midpoint of the bus capacitor, a second input end of the filter module is connected to the midpoint of the first bridge arm, a third input end of the filter module is connected to the midpoint of the second bridge arm, and the filter module is used for filtering the voltage between the midpoint of the bus capacitor, the midpoint of the first bridge arm and the midpoint of the first bridge arm, so as to output target alternating voltages of different voltage levels. The technical scheme of the application meets the power supply demand of different voltage levels and improves the power density of multi-stage power supply equipment.

Description

Technical Field

[0001] This application relates to the field of inverter technology, and in particular to a single-phase inverter circuit and a single-phase inverter. Background Technology

[0002] Electrical equipment often requires power supply at different voltage levels, such as 380V and 220V. Currently, multi-stage power supply is commonly used to meet the power supply requirements of different voltage levels, such as a power supply form with a single-phase inverter and transformer or a power supply form with a three-phase inverter. However, the overall size of the power supply equipment using multi-stage power supply is relatively large, resulting in a lower power density. Summary of the Invention

[0003] The main objective of this application is to provide a single-phase inverter circuit that aims to meet the power supply requirements of different voltage levels while improving the power density of multi-stage power supply equipment.

[0004] To achieve the above objectives, this application proposes a single-phase inverter circuit, which includes:

[0005] DC source;

[0006] An inverter bridge includes a first bridge arm and a second bridge arm, wherein the first bridge arm is connected to the positive and negative terminals of the DC source, respectively, and the second bridge arm is connected to the positive and negative terminals of the DC source, respectively.

[0007] Bus capacitors, which are respectively connected to the positive and negative terminals of the DC source;

[0008] The filtering module has a first input terminal connected to the midpoint of the bus capacitor, a second input terminal connected to the midpoint of the first bridge arm, and a third input terminal connected to the midpoint of the second bridge arm. The filtering module is used to filter the voltage between the midpoint of the bus capacitor, the midpoint of the first bridge arm, and the midpoint of the second bridge arm to output target AC voltages of different voltage levels.

[0009] Optionally, the bus capacitor includes a first capacitor and a second capacitor connected in series. The first capacitor is connected to the positive terminal of the DC source and the second capacitor, respectively, and one end of the second capacitor relative to the first capacitor is connected to the negative terminal of the DC source.

[0010] Optionally, the capacitance value of the first capacitor is equal to the capacitance value of the second capacitor.

[0011] Optionally, the single-phase inverter circuit further includes a modulation module. The first output terminal of the modulation module is connected to the first bridge arm and is used to input a first control signal generated according to a first preset modulation wave to the first bridge arm to control the switching action of the switching element group in the first bridge arm. The second output terminal of the modulation module is connected to the second bridge arm and is used to input a second control signal generated according to a second preset modulation wave to the second bridge arm to control the switching action of the switching element group in the second bridge arm.

[0012] Optionally, the phase of the first preset modulation wave is different from the phase of the second preset modulation wave.

[0013] Optionally, the target AC voltages at different voltage levels include a first target AC voltage, a second target AC voltage, and a third target AC voltage. The modulation ratio of the first preset modulation wave and the modulation ratio of the second preset modulation wave are used together to control the voltage levels of the first target AC voltage and the second target AC voltage. The phase difference between the first preset modulation wave and the second preset modulation wave is used to control the voltage level of the third target AC voltage obtained by superimposing the first target AC voltage and the second target AC voltage.

[0014] Optionally, the filtering module is any of the following filtering circuits: L-filter circuit, LC-filter circuit, and LCL-filter circuit.

[0015] Optionally, the LC filter circuit includes a first inductor, a second inductor, a third inductor, a third capacitor, and a fourth capacitor. One end of the first inductor serves as the first input terminal of the filter module, one end of the second inductor serves as the second input terminal of the filter module, and one end of the third inductor serves as the third input terminal of the filter module. The third capacitor connects the other ends of the first inductor and the second inductor, and the fourth capacitor connects the other ends of the second inductor and the third inductor. Target AC voltages of different voltage levels are formed between the three terminals of the first inductor, the second inductor, and the third inductor.

[0016] Optionally, the first bridge arm is formed by connecting a first group of switching elements and a second group of switching elements in series, and the second bridge arm is formed by connecting a third group of switching elements and a fourth group of switching elements in series.

[0017] To achieve the above objectives, this application also provides a control method for a single-phase inverter circuit. The single-phase inverter circuit includes an inverter bridge, a filter module, and a DC source. The inverter bridge includes a first arm and a second arm. The first arm is connected to the positive and negative terminals of the DC source, respectively, and the second arm is also connected to the positive and negative terminals of the DC source. The single-phase inverter circuit further includes a bus capacitor, which is connected to the positive and negative terminals of the DC source. The first input terminal of the filter module is connected to the midpoint of the bus capacitor, the second input terminal of the filter module is connected to the midpoint of the first arm, and the third input terminal of the filter module is connected to the midpoint of the second arm. The control method for the single-phase inverter circuit includes:

[0018] Acquire a first control signal and a second control signal, wherein the first control signal is generated by the modulation module according to a first preset modulation wave, and the second control signal is generated by the modulation module according to a second preset modulation wave;

[0019] The switching action of the switching element group of the first bridge arm is controlled according to the first control signal, and the switching action of the switching element group of the second bridge arm is controlled according to the second control signal, so as to generate initial AC voltages of different voltage levels among the midpoint of the bus capacitor, the midpoint of the first bridge arm and the midpoint of the second bridge arm.

[0020] The filtering module filters the initial AC voltages of different voltage levels to obtain target AC voltages of different voltage levels.

[0021] To achieve the above objectives, this application also proposes a single-phase inverter, which includes the single-phase inverter circuit described above, and will not be repeated here.

[0022] The technical solution of this application constructs a single-phase inverter circuit by setting up a DC source, an inverter bridge, a bus capacitor, and a filter module. In this single-phase inverter circuit, the first input terminal of the filter module is connected to the midpoint of the bus capacitor, the second input terminal of the filter module is connected to the midpoint of the first bridge arm, and the third input terminal of the filter module is connected to the midpoint of the second bridge arm. This creates a circuit structure similar to a three-phase structure within the single-phase inverter circuit. Furthermore, the filter module filters the voltage between the midpoint of the bus capacitor, the midpoint of the first bridge arm, and the midpoint of the second bridge arm. After filtering, target AC voltages with different voltage levels can be output. Compared with the current power supply form of single-phase inverter plus transformer, it can provide target AC voltages with different voltage levels without setting up a transformer. Compared with the current power supply form of three-phase inverter, it reduces the number of bridge arms in the inverter bridge and can provide target AC voltages with different voltage levels without setting up a three-phase inverter bridge. Therefore, it reduces the overall size of the multi-stage power supply equipment. So while meeting the power supply requirements of different voltage levels, it improves the power density of the multi-stage power supply equipment. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0024] Figure 1 This is a circuit functional block diagram of a single-phase inverter circuit when the filtering module in this application is an LC filter circuit;

[0025] Figure 2 This is a circuit functional block diagram of a single-phase inverter circuit when the filtering module in this application is an L-filter circuit;

[0026] Figure 3 A schematic diagram of the circuit structure of a multi-stage power supply device corresponding to the current power supply form of a single-phase inverter plus a transformer;

[0027] Figure 4 A schematic diagram of the circuit structure of a multi-stage power supply device corresponding to the current power supply form of a three-phase inverter;

[0028] Figure 5 This is a schematic diagram of the circuit structure of a single-phase inverter circuit that includes a modulation module in this application.

[0029] Figure 6 This is a flowchart illustrating an embodiment of the control method for a single-phase inverter circuit in this application.

[0030] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0031] Explanation of icon numbers:

[0032] Detailed Implementation

[0033] 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 a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0034] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0035] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0036] To address the issue of large overall size and low power density in current multi-stage power supply systems, this application proposes a single-phase inverter circuit, referring to... Figure 1 In one embodiment of this application, the single-phase inverter circuit includes a main power module and a filter module. The main power module includes a DC source U. dc Inverter bridge and bus capacitors.

[0037] In this embodiment, the inverter bridge has a first bridge arm 100 and a second bridge arm 200, which are connected in parallel. The first bridge arm 100 is connected to a DC source U. dc The positive and negative terminals are connected to the DC source U on the second bridge arm 200. dc The positive and negative terminals; the bus capacitors are respectively connected to the DC source U. dcThe filter module has a positive and a negative terminal; the filter module has a first input terminal N, a second input terminal R and a third input terminal S. The first input terminal N of the filter module is connected to the midpoint N' of the bus capacitor, the second input terminal of the filter module is connected to the midpoint R' of the first bridge arm 100, and the third input terminal S of the filter module is connected to the midpoint S' of the second bridge arm 200.

[0038] In this embodiment, the filtering module is any of the following filtering circuits: L-filter circuit, LC-filter circuit, and LCL-filter circuit.

[0039] As an example, refer to Figure 1 The LC filter circuit includes a first inductor L1, a second inductor L2, a third inductor L3, a third capacitor C4, and a fourth capacitor C5. One end of the first inductor L1 serves as the first input terminal of the filter module, one end of the second inductor L2 serves as the second input terminal of the filter module, and one end of the third inductor L3 serves as the third input terminal of the filter module. The third capacitor C3 is connected to the other end of the first inductor and the other end of the second inductor, and the fourth capacitor C4 is connected to the other end of the second inductor and the other end of the third inductor. Target AC voltages of different voltage levels are formed between the other ends of the first inductor L1, the second inductor L2, and the third inductor L3.

[0040] As an example, refer to Figure 2 The L-filter circuit includes a first inductor L1, a second inductor L2, and a third inductor L3. One end of the first inductor L1 serves as the first input terminal of the filter module, one end of the second inductor L2 serves as the second input terminal of the filter module, and one end of the third inductor L3 serves as the third input terminal of the filter module. The other ends of the first inductor L1, the second inductor L2, and the third inductor L3 form target AC voltages of different voltage levels.

[0041] In this embodiment, the bus capacitor includes a first capacitor C1 and a second capacitor C2 connected in series. The first capacitor C1 is connected to the DC source U. dc The positive terminal of capacitor C1 is connected to the second capacitor C2, and one end of the second capacitor C2 relative to the first capacitor C1 is connected to the DC source U. dc For example, the negative terminal connection can be configured such that the capacitance value of the first capacitor C1 is equal to the capacitance value of the second capacitor C2.

[0042] In this embodiment, the first bridge arm 100 is formed by connecting the first switch element group S1 and the third switch element group S3 in series, and the second bridge arm 200 is formed by connecting the second switch element group S2 and the fourth switch element group S4 in series. By controlling the switching actions of the first switch element group S1, the second switch element group S2, the third switch element group S3, and the fourth switch element group S4, the DC source U can be switched. dc The output DC power is converted to AC power. When the first switching element group S1 and the second switching element group S2 are turned on, while the third switching element group S3 and the fourth switching element group S4 are turned off, the voltage V between the midpoint R' of the first bridge arm 100 and the midpoint N' of the bus capacitor is... R’N’ For Udc / 2, the voltage V between the midpoint S' of the second bridge arm 200 and the midpoint N' of the bus capacitor is... S’N’ Udc / 2; When the first switching element group S1 and the second switching element group S2 are open, and the third switching element group S3 and the fourth switching element group S4 are closed, the voltage V between the midpoint R' of the first bridge arm 100 and the midpoint N' of the bus capacitor is... R’N’ The voltage V between the midpoint S' of the second bridge arm 200 and the midpoint N' of the bus capacitor is -Udc / 2. S’N’ It is -Udc / 2.

[0043] As an example, an SPWM wave can be constructed by controlling the switching actions of the first switching element group S1, the second switching element group S2, the third switching element group S3, and the fourth switching element group S4 through a preset modulation method. After filtering by the filtering module, the target AC voltage of the required voltage level is output.

[0044] In this embodiment, the filtering module also has a first output terminal N, a second output terminal R, and a third output terminal S. The filtering module filters the voltage V between the midpoint R' of the first bridge arm 100 and the midpoint N' of the bus capacitor. R’N’ After filtering, the target AC output voltage V with the first voltage level is obtained. RN This refers to the voltage between the second output terminal R and the first output terminal N of the filter module; the voltage V between the midpoint S' of the second bridge arm 200 and the midpoint N' of the bus capacitor is also measured by the filter module. S’N’ After filtering, the target AC output voltage V with the first voltage level is obtained. SN This is the voltage between the third output terminal S and the first output terminal N of the filter module; further, the output voltage V... RN and output voltage V SN By superimposing these values, we can obtain the target AC output voltage with the second voltage level, which is also the voltage V between the second output terminal R and the third output terminal S of the filter module. RSThis enables the use of a single-phase inverter circuit to output a target AC voltage at different voltage levels.

[0045] This embodiment constructs a three-phase voltage by drawing out the bus midpoint from a single-phase full-bridge inverter and combining it with a filter module. Compared to... Figure 3 The single-phase inverter plus transformer power supply shown in the diagram can provide three-phase power supply of different voltage levels without the need for a transformer, compared to... Figure 4 The power supply configuration of the three-phase inverter shown in the figure is different from that of the single-phase inverter circuit in this embodiment. The inverter bridge has fewer arms, which can realize three-phase power supply of different voltage levels. Therefore, while ensuring three-phase power supply of different voltage levels, the overall size of the power supply equipment of the multi-stage power supply method is reduced, thereby improving the power density of the multi-stage power supply equipment and reducing the cost of the multi-stage power supply equipment.

[0046] Furthermore, referring to Figure 5 The single-phase inverter circuit also includes a modulation module.

[0047] In this embodiment, the modulation module includes a first operational amplifier and a second operational amplifier. The output terminal of the first operational amplifier is connected to the first switching element group S1 and the third switching element group S3 of the first bridge arm 100, respectively. The output terminal of the second operational amplifier is connected to the second switching element group S2 and the fourth switching element group S4 of the second bridge arm 200, respectively.

[0048] In this embodiment, a first preset modulation wave and a triangular wave are input to the first operational amplifier via the input terminal of the first operational amplifier. The first operational amplifier compares the first preset modulation wave and the triangular wave to generate a first control signal. The first control signal flows through the output terminal of the first operational amplifier to the first switching element group S1 and the third switching element group S3 of the first bridge arm 100, thereby controlling the switching action of the first switching element group S1 and the third switching element group S3 of the first bridge arm 100. A second preset modulation wave and a triangular wave are input to the second operational amplifier via the input terminal of the second operational amplifier. The second operational amplifier compares the second preset modulation wave and the triangular wave to generate a second control signal. The second control signal flows through the output terminal of the second operational amplifier to the second switching element group S2 and the fourth switching element group S4 of the second bridge arm 200, thereby controlling the switching action of the second switching element group S2 and the fourth switching element group S4 of the second bridge arm 200.

[0049] In this embodiment, the first preset modulation wave and the triangular wave have a first modulation ratio, and the second preset modulation wave and the triangular wave have a second modulation ratio. The first modulation ratio and the second modulation ratio can be set to be the same. By controlling the magnitude of the first modulation ratio and the magnitude of the second modulation ratio, the output voltage V can be controlled. SNand output voltage V RN The voltage level can be set; the phase difference between the first preset modulation wave and the second preset modulation wave can be set, and the output voltage V can be controlled by controlling the phase difference between the first preset modulation wave and the second preset modulation wave. SN and output voltage V RN The output voltage V obtained after superposition RS Size.

[0050] As an example, suppose a DC source U dc =700V, first preset modulation wave Second preset modulation wave The phase difference between the first preset modulation wave and the second preset modulation wave The first modulation ratio and the second modulation ratio are both Thus, the output voltage V SN The peak voltage is 311V, the effective voltage is 220V, and the output voltage is V. RN The peak voltage is 311V, the effective voltage is 220V, and the output voltage is... Therefore, the output voltage V RS The peak voltage is 539V, and the effective voltage is 380V. Therefore, in this embodiment, with the DC source voltage and modulation ratio remaining constant, the output voltage V can be adjusted by adjusting the phase difference between the first preset modulation wave and the second preset modulation wave. RS The magnitude of the voltage level can be adjusted to obtain the desired output target AC voltage. Therefore, in this embodiment, the single-phase inverter can provide multiple output voltage levels. When the output voltage of the DC source remains unchanged, the magnitude of the output voltage level can be controlled by adjusting the modulation ratio corresponding to the first preset modulation wave, the modulation ratio corresponding to the second preset modulation wave, and the phase difference between the first preset modulation wave and the second preset modulation wave.

[0051] Based on the above-described single-phase inverter circuit, this application also provides a control method for the single-phase inverter circuit.

[0052] Reference Figure 6 , and combined Figures 1 to 5 In one embodiment, the control method for the single-phase inverter circuit includes:

[0053] Step S10: Obtain a first control signal and a second control signal, wherein the first control signal is generated by the modulation module according to a first preset modulation wave, and the second control signal is generated by the modulation module according to a second preset modulation wave;

[0054] Step S20: Control the switching action of the switching element group of the first bridge arm according to the first control signal, and control the switching action of the switching element group of the second bridge arm according to the second control signal, so as to generate initial AC voltages of different voltage levels among the midpoint of the bus capacitor, the midpoint of the first bridge arm and the midpoint of the second bridge arm.

[0055] Step S30: The initial AC voltages of different voltage levels are filtered by the filtering module to obtain the target AC voltages of different voltage levels.

[0056] As an example, steps S10 to S30 include: generating a first control signal by inputting a first preset modulation wave and a triangular wave into the first operational amplifier of the modulation module, and generating a second control signal by inputting a second preset modulation wave and a triangular wave into the second operational amplifier of the modulation module; controlling the switching action of the first switching element group S1 and the third switching element group S3 in the first bridge arm 100 by transmitting the first control signal to the first bridge arm 100, and controlling the switching action of the second switching element group S2 and the fourth switching element group S4 in the second bridge arm 200 by transmitting the second control signal to the second bridge arm 200, so as to control the inverter bridge to convert the DC power output from the DC source into AC power, thereby generating initial AC voltages of different voltage levels between the midpoint of the bus capacitor, the midpoint of the first bridge arm 100 and the midpoint of the second bridge arm 200; filtering the initial AC voltages of different voltage levels by the filtering module, and generating target AC voltages of different voltage levels between the first output terminal N, the second output terminal R and the third output terminal S of the filtering module. The first modulation ratio corresponding to the first preset modulation wave and the second modulation ratio corresponding to the second preset modulation wave are used together to control the voltage V between the first output terminal N and the second output terminal R of the filter module. RN The voltage level and the voltage V between the first output terminal N and the third output terminal S of the control filter module. SN The voltage level, and because the voltage between the second output terminal R and the third output terminal S of the filter module is determined by V RN and V SN Therefore, the first modulation ratio corresponding to the first preset modulation wave, the second modulation ratio corresponding to the second preset modulation wave, and the phase difference between the first preset modulation wave and the second preset modulation wave are used to jointly control the voltage V between the second output terminal R and the third output terminal S of the filter module. RSThe voltage level can be adjusted by changing the size of the first modulation ratio, the size of the second modulation ratio, and the phase difference between the first preset modulation wave and the second preset modulation wave. The output of the single-phase inverter circuit can be controlled to produce target AC voltages of different voltage levels. The single-phase inverter circuit has a smaller overall size and therefore a higher power density. Therefore, the embodiments of this application improve the power density of multi-stage power supply equipment while meeting the power supply requirements of different voltage levels.

[0057] In addition, this application also provides a single-phase inverter, which includes the single-phase inverter circuit described above. It is understood that since the single-phase inverter circuit described above is used in the single-phase inverter, the embodiments of the single-phase inverter include all the technical solutions of all embodiments of the single-phase inverter circuit described above, and the technical effects achieved are exactly the same, so they will not be repeated here.

[0058] The above description is merely a preferred embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the content of this application's specification and drawings under the concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A single phase inverter circuit, characterized by, The single-phase inverter circuit comprises: a direct current source; an inverter bridge comprising a first bridge arm and a second bridge arm, the first bridge arm being connected to a positive pole and a negative pole of the direct current source respectively, and the second bridge arm being connected to the positive pole and the negative pole of the direct current source respectively; a bus capacitor connected to the positive pole and the negative pole of the direct current source respectively; a filter module, a first input end of the filter module being connected to a midpoint of the bus capacitor, a second input end of the filter module being connected to a midpoint of the first bridge arm, a third input end of the filter module being connected to a midpoint of the second bridge arm, the filter module being configured to filter a voltage between the midpoint of the bus capacitor, the midpoint of the first bridge arm and the midpoint of the second bridge arm, so as to output target alternating voltages of different voltage levels, wherein the single-phase inverter circuit further comprises a modulation module, a first output end of the modulation module being connected to the first bridge arm, and configured to input a first control signal generated according to a first preset modulation wave to the first bridge arm, so as to control switching actions of a group of switching elements in the first bridge arm; a second output end of the modulation module being connected to the second bridge arm, and configured to input a second control signal generated according to a second preset modulation wave to the second bridge arm, so as to control switching actions of a group of switching elements in the second bridge arm, wherein a modulation ratio corresponding to the first preset modulation wave, a modulation ratio corresponding to the second preset modulation wave and a phase difference between the first preset modulation wave and the second preset modulation wave are adjusted, so as to control the target alternating voltages of different voltage levels to be output.

2. The single-phase inverter circuit of claim 1, wherein The bus capacitor comprises a first capacitor and a second capacitor connected in series, the first capacitor being connected to the positive pole and the second capacitor of the direct current source respectively, and the second capacitor being connected to the negative pole of the direct current source relative to one end of the first capacitor.

3. The single-phase inverter circuit of claim 2, wherein, The capacitance value of the first capacitor is equal to the capacitance value of the second capacitor.

4. The single-phase inverter circuit of claim 1, wherein, The phase of the first preset modulation wave is different from the phase of the second preset modulation wave.

5. The single-phase inverter circuit of claim 4, wherein, The target alternating voltages of different voltage levels comprise a first target alternating voltage, a second target alternating voltage and a third target alternating voltage, the modulation ratio of the first preset modulation wave and the modulation ratio of the second preset modulation wave being used together to control voltage levels of the first target alternating voltage and the second target alternating voltage, and the phase difference between the first preset modulation wave and the second preset modulation wave being used to control a voltage level of the third target alternating voltage obtained by superimposing the first target alternating voltage and the second target alternating voltage.

6. The single-phase inverter circuit of claim 1, wherein, The filter module is any one of the following filter circuits: an L filter circuit, an LC filter circuit and an LCL filter circuit.

7. The single-phase inverter circuit of claim 6, wherein The LC filter circuit comprises a first inductor, a second inductor, a third inductor, a third capacitor and a fourth capacitor, one end of the first inductor is the first input end of the filter module, one end of the second inductor is the second input end of the filter module, one end of the third inductor is the third input end of the filter module, the third capacitor connects the other end of the first inductor and the other end of the second inductor, the fourth capacitor connects the other end of the second inductor and the other end of the third inductor, and the other end of the first inductor, the other end of the second inductor and the other end of the third inductor form target alternating voltages of different voltage levels.

8. A control method of a single-phase inverter circuit, the single-phase inverter circuit comprising an inverter bridge, a filter module, and a direct current source, the inverter bridge comprising a first bridge arm and a second bridge arm, the first bridge arm being connected to a positive pole and a negative pole of the direct current source, respectively, the second bridge arm being connected to the positive pole and the negative pole of the direct current source, respectively, characterized in that, The single-phase inverter circuit further comprises a bus capacitor, the bus capacitor is connected to the positive and negative poles of the DC power supply respectively, the first input end of the filter module is connected to the midpoint of the bus capacitor, the second input end of the filter module is connected to the midpoint of the first bridge arm, the third input end of the filter module is connected to the midpoint of the second bridge arm, the single-phase inverter circuit further comprises a modulation module, the first output end of the modulation module is connected to the first bridge arm; The second output end of the modulation module is connected to the second bridge arm, and the control method of the single-phase inverter circuit comprises: obtaining a first control signal and a second control signal, wherein the first control signal is generated by the modulation module according to a first preset modulation wave, and the second control signal is generated by the modulation module according to a second preset modulation wave; controlling the switching action of the switching element group of the first bridge arm according to the first control signal, and controlling the switching action of the switching element group of the second bridge arm according to the second control signal, so as to generate initial alternating voltages of different voltage levels among the midpoint of the bus capacitor, the midpoint of the first bridge arm and the midpoint of the second bridge arm; filtering the initial alternating voltages of different voltage levels through the filter module to obtain target alternating voltages of different voltage levels, wherein the modulation ratio corresponding to the first preset modulation wave, the modulation ratio corresponding to the second preset modulation wave and the phase difference between the first preset modulation wave and the second preset modulation wave are adjusted to control the output of target alternating voltages of different voltage levels.

9. A single-phase inverter, characterized by The single-phase inverter comprises the single-phase inverter circuit according to any one of claims 1 to 7. The single-phase inverter comprises the single-phase inverter circuit according to any one of claims 1 to 7.

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