A common ground type dual output switched capacitor type multi-level inverter

Abstract

The present invention discloses a common ground dual-output switched capacitor type multi-level inverter, comprising a power input terminal, a switched capacitor module A, a switched capacitor module B, an H-bridge unit and two AC output terminals V o1 、V o2 , where the H-bridge structure includes a switch tube S 1 , S 2 , S 3 , S 4 , which are the upper bridge arm switch tube of the first bridge arm, the lower bridge arm switch tube of the first bridge arm, the upper bridge arm switch tube of the second bridge arm, and the lower bridge arm switch tube of the second bridge arm respectively; the negative electrodes of the output ends of the switch capacitor modules A and B are connected to the common ground, and are connected to the common ground of the AC output loads z1 and z2 to form a common ground end; the positive electrode of the output end of the switch capacitor module A is connected to the switch tube S 1 , S 3 The positive electrode of the output end of the switch capacitor module B is connected to the switch tube S 2 , S 4 The present invention has the advantages of common ground for input and output voltage, continuous input current and high gain. The system has two output ports, and the number of devices used in each output port is less than that of similar topologies, and the total harmonic distortion rate of the output waveform is low.

Description

Technical Field

[0001] The present invention belongs to the field of multi-level inverters and new energy distributed grid-connected power generation, and in particular relates to a common ground dual-output switch capacitor type multi-level inverter and a modulation method thereof. Background Art

[0002] The current photovoltaic inverter has the following problems: 1. There is leakage current when connected to the power grid; 2. There is no boost effect. The existence of leakage current will lead to safety hazards, and the reason for this is that the input and output are not grounded. For this problem, some people have proposed a common ground inverter. The lack of boost characteristics will lead to a large output voltage THD, so the required filter is very large, resulting in low efficiency. The switched capacitor inverter has a good boost effect and is easy to adjust. It is often used in multi-level topology structures. Therefore, the present invention proposes a common ground dual-output switched capacitor multi-level inverter and a modulation method thereof. Summary of the invention

[0003] The object of the present invention is to provide a common ground dual-output switched capacitor type multi-level inverter and a modulation method thereof.

[0004] The technical solution to achieve the purpose of the present invention is: a common ground dual-output switched capacitor type multi-level inverter, including a power input terminal, a switched capacitor module A, a switched capacitor module B, an H-bridge unit and two AC output terminals V o1 、V o2 The H-bridge structure includes switch tube S1, switch tube S2, switch tube S3, and switch tube S4. The upper bridge arm switch tube of the first bridge arm is S1, the lower bridge arm switch tube of the first bridge arm is S2, the upper bridge arm switch tube of the second bridge arm is S3, and the lower bridge arm switch tube of the second bridge arm is S4; the midpoint of the first bridge arm is the AC output terminal V o1 The midpoint of the second bridge arm is the AC output terminal V o2 The non-common ground ends of

[0005] The power input terminal is connected to the positive electrode of the input power Vin, and the negative electrode of the input power Vin is connected to the common ground;

[0006] The input ends of the switch capacitor module A and the switch capacitor module B are connected to the power input end, and the negative electrodes of the output ends of the switch capacitor module A and the switch capacitor module B are connected to a common ground point, and are connected to the common ground points of the AC output loads z1 and z2 to form a common ground end; the positive electrode of the output end of the switch capacitor module A is connected to the cathode of the switch tube S1 and the cathode of the switch tube S3; the positive electrode of the output end of the switch capacitor module B is connected to the anode of the switch tube S2 and the anode of the switch tube S4;

[0007] The cathode of the switch tube S1 is connected to the cathode of the switch tube S3 and the positive output terminal of the switch capacitor module A, and the anode of the switch tube S1 is connected to the cathode of the switch tube S2 and the non-common ground terminal of the AC output load z1; the anode of the switch tube S2 is connected to the anode of the switch tube S4 and the positive output terminal of the switch capacitor module B; the anode of the switch tube S3 is connected to the cathode of the switch tube S4 and the non-common ground terminal of the AC output load z2;

[0008] The two AC output terminals V o1 、V o2 Load z1 and load z2 are connected respectively, and the other ends of AC load z1 and AC load z2 are grounded in common.

[0009] Furthermore, the switch tube S1 , the switch tube S2 , the switch tube S3 and the switch tube S4 are MOSFET or IGBT.

[0010] Furthermore, the switch capacitor module A and the switch capacitor module B use the same type of switch capacitor topology or different types of switch capacitor topologies.

[0011] Furthermore, the switch capacitor module A and the switch capacitor module B adopt a series-parallel, cascade, ladder or Fibonacci switch capacitor topology.

[0012] Furthermore, the switching devices used in the switch capacitor module A and the switch capacitor module B are MOSFET or IGBT.

[0013] Furthermore, the working mode of the inverter H-bridge unit is as follows:

[0014] Working mode 1: control the switch devices S1 and S4 to be turned on, and control the switch tubes S2 and S3 to be turned off;

[0015] Working mode 2: control the switch devices S1 and S3 to be turned on, and control the switch tubes S2 and S4 to be turned off;

[0016] Working mode 3: control the switch devices S2 and S3 to be turned on, and control the switch tubes S1 and S4 to be turned off;

[0017] Working mode 4: control the switch devices S2 and S4 to be turned on, and control the switch tubes S1 and S3 to be turned off.

[0018] Furthermore, the switch capacitor module A and the switch capacitor module B respectively generate a DC step-shaped sinusoidal half-wave, and the AC output terminal V o1 、V o2 The positive half-wave is generated by the switched capacitor module B, and the AC output terminal V o1 、V o2 The negative half-wave is generated by the switched capacitor module A.

[0019] Furthermore, the output voltage V A and the output voltage V of the switched capacitor module B B The same, the output voltage frequency f of the switched capacitor module A A and the output voltage frequency f of the switched capacitor module B B The same; the AC output terminal V o1 、V o2 The voltage effective values ​​are the same and the phase difference is 180 degrees.

[0020] A control method for a common ground dual-output switched capacitor type multi-level inverter is provided, and based on the common ground dual-output switched capacitor type multi-level inverter, multi-level inverter control is realized.

[0021] Furthermore, LS-SPWM, SHE or NLC is used to implement multi-level inverter control.

[0022] Compared with the prior art, the present invention has the following significant advantages: 1) the input and load share the same ground, which is beneficial to suppressing system leakage current; 2) permanent non-zero input current; 3) compared with the same type of common-ground SC inverter, it has a higher boost multiple with the same number of components; 4) two independently controllable output AC voltage sources (same amplitude, opposite phase) are provided, and the two loads do not need to be symmetrical and do not affect each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a circuit diagram of an inverter in an embodiment of the present invention;

[0024] Figure 2 is a circuit diagram of an inverter using a series-parallel topology structure in an embodiment of the present invention;

[0025] Figure 3 is a schematic diagram of a working current path of an inverter working mode 1 in an embodiment of the present invention;

[0026] Figure 4 is a schematic diagram of a working current path of an inverter working mode 2 in an embodiment of the present invention;

[0027] Figure 5 is a schematic diagram of a working current path of an inverter working mode 3 in an embodiment of the present invention;

[0028] Figure 6 is a schematic diagram of a working current path of an inverter working mode 4 in an embodiment of the present invention;

[0029] Figure 7 is a schematic diagram of a working current path of an inverter working mode 5 in an embodiment of the present invention;

[0030] Figure 8is a schematic diagram of a working current path of an inverter working mode 6 in an embodiment of the present invention;

[0031] Fig. 9 is a schematic diagram of a working current path of an inverter working mode 7 in an embodiment of the present invention;

[0032] Fig.10 is a schematic diagram of a working current path of an inverter working mode 8 in an embodiment of the present invention;

[0033] Fig.11 is a schematic diagram of a working current path of an inverter working mode 9 in an embodiment of the present invention;

[0034] Fig.12 is a waveform diagram between input and output grounds in an embodiment of the present invention;

[0035] Fig.13 is an output voltage waveform diagram of the inverter in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0037] like Figure 1 As shown, a common ground dual-output switched capacitor type multi-level inverter includes a power input terminal, a switched capacitor module A, a switched capacitor module B, an H-bridge unit, and two AC output terminals V o1 、V o2 .

[0038] The H-bridge unit includes switch tubes S1, S2, S3, and S4. The switch devices used may be, but are not limited to, controllable switch devices such as MOSFET and IGBT, and are defined as follows: the side where current flows into the device is the anode, and the side where current flows out of the device is the cathode.

[0039] The upper bridge arm switch of the first bridge arm is S1, the lower bridge arm switch of the first bridge arm is S2, the upper bridge arm switch of the second bridge arm is S3, and the lower bridge arm switch of the second bridge arm is S4. The midpoint of the first bridge arm is the AC output V o1 The non-common ground end of the second bridge arm is the midpoint of the AC output V o2The cathode of the switch tube S1 is connected to the cathode of the switch tube S3 and the positive output terminal of the switch capacitor module A, the anode of the switch tube S1 is connected to the cathode of the switch tube S2 and the non-common ground terminal of the AC output load z1, the anode of the switch tube S2 is connected to the anode of the switch tube S4 and the positive output terminal of the switch capacitor module B, and the anode of the switch tube S3 is connected to the cathode of the switch tube S4 and the non-common ground terminal of the AC output load z2.

[0040] The switch capacitor module A and the switch capacitor module B may use the same type of switch capacitor topology or different types of switch capacitor topologies, and their structures may be, but are not limited to, series-parallel, cascade, ladder, Fibonacci, and other switch capacitor topologies. The switch devices used in the switch capacitor module A and the switch capacitor module B may be, but are not limited to, MOSFET or IGBT.

[0041] The input end of the switch capacitor module A is connected to the power input end, and the power input end is connected to the input power supply V in The positive electrode of the output end of the switch capacitor module A is connected to the cathode of the switch tube S1 and the cathode of the switch tube S3, and the negative electrode of the output end of the switch capacitor module A is connected to the common ground end of the load z1 and the load z2. The input end of the switch capacitor module B is connected to the power input end, the positive electrode of the output end of the switch capacitor module B is connected to the anode of the switch tube S2 and the anode of the switch tube S4, and the negative electrode of the output end of the switch capacitor module B is connected to the common ground end of the load z1 and the load z2.

[0042] The two AC output terminals V o1 、V o2 Connect load z1 and load z2 respectively. The other ends of AC load z1 and AC load z2 are connected to the same ground and connected to the input power supply V in of the negative electrode.

[0043] The following explains the working principle and modulation process of the common ground dual-output switched capacitor type multi-level inverter through the analysis of the H-bridge unit and the switched capacitor module.

[0044] In the above-mentioned common ground dual-output switched capacitor multi-level inverter, the H-bridge unit has four working modes:

[0045] Working mode 1: control the switch devices S1 and S4 to be turned on, and control the switch tubes S2 and S3 to be turned off;

[0046] Working mode 2: control the switch devices S1 and S3 to be turned on, and control the switch tubes S2 and S4 to be turned off;

[0047] Working mode 3: control the switch devices S2 and S3 to be turned on, and control the switch tubes S1 and S4 to be turned off;

[0048] Working mode 4: control the switch devices S2 and S4 to be turned on, and control the switch tubes S1 and S3 to be turned off.

[0049] Through the above four working modes, two sets of AC outputs can be achieved.

[0050] In the above-mentioned common ground dual-output switched capacitor multi-level inverter, the switched capacitor module A and the switched capacitor module B respectively generate a DC step-shaped sinusoidal half-wave, wherein the waveform generated by the switched capacitor module A is used as the AC output terminal V o1 、V o2 The negative half-wave of the switched capacitor module B is used as the waveform at the AC output terminal V o1 、V o2 The output voltage V of the switched capacitor module A is A and the output voltage V of the switched capacitor module B B The same, the output voltage frequency f of the switched capacitor module A A and the output voltage frequency f of the switched capacitor module B B The output voltage V o1 and V o2 The effective value is the same and the phase difference is 180 degrees. The output voltage frequency f O It is half of the output voltage frequency of the switched capacitor module A and the switched capacitor module B.

[0051] The modulation method used may be, but is not limited to, LS-SPWM, SHE, NLC and other multi-level inverter control methods.

[0052] In summary, the present invention has the characteristics of multi-level output, high gain, common ground structure, and multi-channel output, eliminates the leakage current of the output and input, and achieves lower voltage harmonics and better power quality on the AC side. The present invention can be used in DC-AC converters of electric vehicles, photovoltaic grid-connected power generation, and distributed power generation systems, which have been hotly studied in recent years.

[0053] Example

[0054] In order to verify the effectiveness of the solution of the present invention, the following simulation experiment is carried out.

[0055] In this embodiment, the input voltage is 40V, the two loads are both 60Ω, the output frequency is 60HZ, and the output power is 400W. L1 =C L2 =C L3 =C L4 =4700μF, capacitor C R1 =C R2 =C R3 =4700μF. The switching devices used are all MOSFETs.

[0056] like Figure 2 As shown, the switch capacitor module A and the switch capacitor module B are connected in series and parallel, and the positive electrode of the DC input power supply Vin is connected to S L12 , S L22 , S L32 , S L42 The drain and S R13 , S R23 , S R33 Source; DC input voltage source V in The negative terminal is connected to S L13 , S L23 , S L33 , S L43 The drain, S R12 , S R22 , S R32 The source and S L11 The source of capacitor C L1 , C L2 , C L3 , C L4 The positive electrode is connected to S L12 , S L22 , S L32 , S L42 The source and S L11 , S L21 , S L31 , S L41 The drain of capacitor C L1 , C L2 , C L3 , C L4 The negative terminal is connected to S L11 , S L21 , S L31 , S L41 The source and S L13 , S L23 , S L33 , S L43 The source of capacitor C R1 , C R2 , C R3 The positive electrode is connected to S R11 , S R21 , S R31 The drain and S R13 , S R23 , S R33 The drain of capacitor C R1 , C R2 , C R3 The negative terminal is connected to S R11 , S R21 , S R31 The source and S L12 , S L22 , S L32 , SL42 of the drain.

[0057] The H-bridge unit includes a switch tube S1, a switch tube S2, a switch tube S3, and a switch tube S4. The source of the switch tube S1 is connected to the source of the switch tube S3 and the positive output terminal of the switch capacitor module A. The drain of the switch tube S1 is connected to the source of the switch tube S2 and the non-common ground terminal of the AC output load z1. The drain of the switch tube S2 is connected to the drain of the switch tube S4 and the positive output terminal of the switch capacitor module B. The drain of the switch tube S3 is connected to the source of the switch tube S4 and the non-common ground terminal of the AC output load z2.

[0058] The inverter output end includes two AC output ends, which are respectively connected to load z1 and load z2. The AC load z1 and the AC load z2 are grounded in common. The common ground end of load z1 and load z2 is connected to the negative end of the switch capacitor module A and the switch capacitor module B. The non-common ground end of load z1 is connected to the drain of the switch tube S1 and the source of the switch tube S2. The non-common ground end of load z2 is connected to the drain of the switch tube S3 and the source of the switch tube S4.

[0059] Based on the series-parallel structure used, through the series-parallel conversion of power supply and capacitor, the inverter can make the two loads obtain the following levels while using a small number of devices:

[0060] V o1 :0, ±V in , ±2V in , ±3V in , ±4V in ;

[0061] V o2 :0, ±V in , ±2V in , ±3V in , ±4V in ;

[0062] Figure 3 to Figure 11 They are the working current paths of the nine working modes of the inverter. The charging circuit in the figure is analyzed in the working mode. The two different dotted lines represent the discharge circuits of the switch capacitor module A and the switch capacitor module B respectively. The dotted device means that the device is not working. The working modes of the inverter are as follows:

[0063] Working mode 1: Control switch device S L11 , S L21 , S L31 , S L41 , S R11 , S R21 , S R31 , S1, S4 are turned on, and the remaining switch devices are turned off. Capacitor C L1 , CL2 , C L3 , C L4 Discharge in series to load z1, power supply V in and capacitor C R1 , C R2 , C R3 Discharged in series to load z2, the output of the inverter is: V o1 =-4V in , V o2 =4V in , the working current path is as follows Figure 3 shown.

[0064] Working mode 2: Control switch device S L12 , S L13 , S L21 , S L31 , S L41 , S R12 , S R13 , S R21 , S R31 , S1, S4 are turned on, and the remaining switch devices are turned off. Power supply V in is the capacitance C L1 , C R1 Charge, capacitor C L2 , C L3 , C L4 Discharge in series to load z1, power supply V in and capacitor C R2 , C R3 Discharged in series to load z2, the output of the inverter is: V o1 =-3V in , V o2 =3V in , the working current path is as follows Figure 4 shown.

[0065] Working mode 3: Control switch device S L12 , S L13 , S L22 , S L23 , S L31 , S L41 , S R12 , S R13 , S R22 , S R23 , S R31 , S1, S4 are turned on, and the remaining switch devices are turned off. Power supply V in is the capacitance C L1 , C L2 , C R1 , C R2 Charge, capacitor C L3 , C L4Discharge in series to load z1, power supply V in and capacitor C R3 Discharged in series to load z2, the output of the inverter is: V o1 =-2V in , V o2 =2V in , the working current path is as follows Figure 5 shown.

[0066] Working mode 4: Control switch device S L12 , S L13 , S L22 , S L23 , S L32 , S L33 , S L41 , S R12 , S R13 , S R22 , S R23 , S R32 , S R33 , S1, S4 are turned on, and the remaining switch devices are turned off. Power supply V in is the capacitance C L1 , C L2 , C L3 , C R1 , C R2 , C R3 Charge, capacitor C L4 Discharge to load z1, power supply V in Discharging to load z2, the output of the inverter is: V o1 =-V in , V o2 =V in , the working current path is as follows Figure 6 shown.

[0067] Working mode 5: Control switch device S L12 , S L13 , S L22 , S L23 , S L32 , S L33 , S L42 , S L43 , S R12 , S R13 , S R22 , S R23 , S R32 , S R33 , S1, S3 are turned on, and the remaining switch devices are turned off. Power supply V in is the capacitance C L1 , C L2 , C L3 , C L4 , CR1 , C R2 , C R3 Charge, the inverter output is: V o1 =0, V o2 =0, the working current path is as follows Figure 7 shown.

[0068] Working mode 6: Control switch device S L12 , S L13 , S L22 , S L23 , S L32 , S L33 , S L41 , S R12 , S R13 , S R22 , S R23 , S R32 , S R33 , S2, S3 are turned on, and the remaining switch devices are turned off. Power supply V in is the capacitance C L1 , C L2 , C L3 , C R1 , C R2 , C R3 Charge, capacitor C L4 Discharge to load z2, power supply V in Discharging to load z1, the output of the inverter is: V o1 =V in , V o2 =-V in , the working current path is as follows Figure 8 shown.

[0069] Working mode 7: Control switch device S L12 , S L13 , S L22 , S L23 , S L31 , S L41 , S R12 , S R13 , S R22 , S R23 , S R31 , S2, S3 are turned on, and the remaining switch devices are turned off. Power supply V in is the capacitance C L1 , C L2 , C R1 , C R2 Charge, capacitor C L3 , C L4 Discharge in series to load z2, power supply V in and capacitor C R3Discharged in series to load z1, the output of the inverter is: V o1 =2V in , V o2 =-2V in , the working current path is as follows Fig. 9 shown.

[0070] Working mode 8: Control switch device S L12 , S L13 , S L21 , S L31 , S L41 , S R12 , S R13 , S R21 , S R31 , S2, S3 are turned on, and the remaining switch devices are turned off. Power supply V in is the capacitance C L1 , C R1 Charge, capacitor C L2 , C L3 , C L4 Discharge in series to load z2, power supply V in and capacitor C R2 , C R3 Discharged in series to load z1, the output of the inverter is: V o1 =3V in , V o2 =-3V in , the working current path is as follows Fig.10 shown.

[0071] Working mode 9: Control switch device S L11 , S L21 , S L31 , S L41 , S R11 , S R21 , S R31 , S2, S3 are turned on, and the remaining switch devices are turned off. Capacitor C L1 , C L2 , C L3 , C L4 Discharge in series to load z2, power supply V in and capacitor C R1 , C R2 , C R3 Discharged in series to load z1, the output of the inverter is: V o1 =4V in , V o2 =-4V in , the working current path is as follows Fig.11 shown.

[0072] The following results were obtained using PSIM simulation. Fig.12 This is the waveform between the input voltage ground and the output voltage ground. The voltage is shown as zero, which verifies the common ground characteristic of this topology. Fig.13 The output voltage waveform shows that the two output phases differ by 180 degrees and have the same RMS value, which is consistent with the theoretical analysis. The structure has a certain voltage boost capability, which verifies the feasibility of the structure.

[0073] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A common ground dual-output switched capacitor multi-level inverter, characterized in that: It includes a power input terminal, a switch capacitor module A, a switch capacitor module B, an H-bridge unit, and two AC output terminals V o1 、V o2 The H-bridge structure includes switch tube S1, switch tube S2, switch tube S3, and switch tube S4. The upper bridge arm switch tube of the first bridge arm is S1, the lower bridge arm switch tube of the first bridge arm is S2, the upper bridge arm switch tube of the second bridge arm is S3, and the lower bridge arm switch tube of the second bridge arm is S4; the midpoint of the first bridge arm is the AC output terminal V o1 The midpoint of the second bridge arm is the AC output terminal V o2 The non-common ground ends of The power input terminal is connected to the positive electrode of the input power Vin, and the negative electrode of the input power Vin is connected to the common ground; The input ends of the switch capacitor module A and the switch capacitor module B are connected to the power input end, and the negative electrodes of the output ends of the switch capacitor module A and the switch capacitor module B are connected to a common ground point, and are connected to the common ground points of the AC output loads z1 and z2 to form a common ground end; the positive electrode of the output end of the switch capacitor module A is connected to the cathode of the switch tube S1 and the cathode of the switch tube S3; the positive electrode of the output end of the switch capacitor module B is connected to the anode of the switch tube S2 and the anode of the switch tube S4; The cathode of the switch tube S1 is connected to the cathode of the switch tube S3 and the positive output terminal of the switch capacitor module A, and the anode of the switch tube S1 is connected to the cathode of the switch tube S2 and the non-common ground terminal of the AC output load z1; the anode of the switch tube S2 is connected to the anode of the switch tube S4 and the positive output terminal of the switch capacitor module B; the anode of the switch tube S3 is connected to the cathode of the switch tube S4 and the non-common ground terminal of the AC output load z2; The two AC output terminals V o1 、V o2 Load z1 and load z2 are connected respectively, and the other ends of AC load z1 and AC load z2 are grounded in common.

2. The common ground dual-output switched capacitor multi-level inverter according to claim 1, characterized in that: The switch tubes S1 , S2 , S3 and S4 are MOSFET or IGBT.

3. The common ground dual-output switched capacitor multi-level inverter according to claim 1, characterized in that: The switch capacitor module A and the switch capacitor module B use the same type of switch capacitor topology or different types of switch capacitor topologies.

4. The common ground dual-output switched capacitor multi-level inverter according to claim 1, characterized in that: The switch capacitor module A and the switch capacitor module B adopt a series-parallel, cascade, ladder or Fibonacci switch capacitor topology.

5. The common ground dual-output switched capacitor multi-level inverter according to claim 1, characterized in that: The switching devices used in the switch capacitor module A and the switch capacitor module B are MOSFET or IGBT.

6. The common ground dual-output switched capacitor multi-level inverter according to claim 1, characterized in that: The working mode of the inverter H-bridge unit is as follows: Working mode 1: control the switch devices S1 and S4 to be turned on, and control the switch tubes S2 and S3 to be turned off; Working mode 2: control the switch devices S1 and S3 to be turned on, and control the switch tubes S2 and S4 to be turned off; Working mode 3: control the switch devices S2 and S3 to be turned on, and control the switch tubes S1 and S4 to be turned off; Working mode 4: control the switch devices S2 and S4 to be turned on, and control the switch tubes S1 and S3 to be turned off.

7. The common ground dual-output switched capacitor multi-level inverter according to claim 1, characterized in that: The switch capacitor module A and the switch capacitor module B respectively generate a DC step-shaped sinusoidal half-wave, and the AC output terminal V o1 、V o2 The positive half-wave is generated by the switched capacitor module B, and the AC output terminal V o1 、V o2 The negative half-wave is generated by the switched capacitor module A.

8. The common ground dual-output switched capacitor multi-level inverter according to claim 7, characterized in that: The output voltage V of the switched capacitor module A A and the output voltage V of the switched capacitor module B B The same, the output voltage frequency f of the switched capacitor module A A and the output voltage frequency f of the switched capacitor module B B The same; the AC output terminal V o1 、V o2 The voltage effective values ​​are the same and the phase difference is 180 degrees.

9. A control method for a common ground dual-output switched capacitor type multi-level inverter, characterized in that: Based on the common ground dual-output switched capacitor multi-level inverter according to any one of claims 1 to 8, multi-level inverter control is implemented.

10. The control method of the common ground dual-output switched capacitor type multi-level inverter according to claim 9, characterized in that: Implement multi-level inverter control using LS-SPWM, SHE or NLC.

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