Front-end single-stage boost / buck three-level inverter

Abstract

A multilevel t-type inverter for connecting a DC power source to an AC grid, the multilevel t-type inverter comprising: a high frequency power inductor; a positive terminal for connecting to a positive DC voltage source; a negative terminal for connecting to a negative DC voltage source; a grid terminal for connecting to the AC grid; a neutral terminal for connecting to a neutral connection of the AC grid; three bidirectional switches; and an output pair filter, wherein the three bidirectional switches can provide different current paths for charging or discharging the high frequency power inductor, respectively.

Description

[Technical Field]

[0001] Related Applications This application claims the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63 / 398,914, filed August 18, 2022, the contents of which are incorporated by reference herein in their entirety. [Background technology]

[0002] The present invention relates to a front-end single-stage boost three-level inverter, and more particularly, but not exclusively, to using such an inverter to connect a DC power source to an AC grid, or to an electric motor, or any load requiring AC power.

[0003] Direct current (DC) photovoltaic (PV) power sources and battery energy storage systems (BESS) are widespread in modern power grids. To utilize DC battery energy on an alternating current (AC) power grid, an inverter is required. One of the most common inverters is the multilevel inverter (MLI). Most non-isolated MLIs are based on a step-down (buck) converter, which assumes that the supply voltage is higher than the amplitude of a sine wave. However, because a basic battery cell voltage is approximately 4 V, a BESS requires approximately 200 cells connected in series. This task is not easy in many designs, so an additional bidirectional power converter is used to connect the BESS to the inverter's DC link. This results in impacts on the cost, efficiency, reliability, and volume of the overall system. A buck-boost converter can vary the output voltage above or below the input voltage. However, the indirect current characteristic of a buck-boost converter increases the peak current in the inductor, and the converter inverts the output voltage, limiting the range of applicable applications.

[0004] The neutral-point clamped (NPC) inverter is a type of multilevel power converter characterized by the use of clamping diodes to ensure proper voltage sharing between the power switches. The three-level NPC inverter provides superior waveform quality compared to two-level inverters, making it a widely used multilevel converter topology that achieves very attractive performance with limited complexity. Each NPC inverter leg contains four transistors and two diodes. The three-level T-type inverter (T 2 I) offers improved harmonic performance, similar to a 3-level NPC inverter. 2 I requires two standard transistors connected in series across the DC link voltage from positive (P) to negative (N) and a bidirectional switch (implemented by two transistors in a common-source configuration) between the midpoint of the transistors and the neutral point, for a total of four transistors per leg. In the NPC topology, two elements are always connected in series when the output is connected to P or N, whereas the 3LT 2 In I, only one element is connected. 2 The performance of I is the highest among the two-level and three-level inverters, reaching 99% at 10 kW. However, it is not as good as the transformerless two-level inverter, the NPC inverter, and the T 2 requires positive (P) and negative (N) voltage supplies that are higher than the sinusoidal amplitude voltage. Summary of the Invention [Problem to be solved by the invention]

[0005] This embodiment can provide a topology for a three-level T-type universal inverter (T2UI), which can accommodate applications where the sinusoidal amplitude is higher or lower than the positive P and negative N supply voltages.

[0006] A multilevel t-type inverter according to a first embodiment of the present invention is a multilevel t-type inverter for connecting a DC power source to an AC grid, and the multilevel t-type inverter comprises: a high frequency power inductor; a positive terminal for connection to a positive DC voltage source; a negative terminal for connection to a negative DC voltage source; a grid terminal for connecting to the AC grid; a neutral terminal for connection to the neutral connection of the AC grid; a plurality of bidirectional switches, each of the plurality of bidirectional switches defining a different current path through the inverter, each path comprising a high frequency power inductor; and an output LC filter.

[0007] The inverter may include a cascaded dual-loop controller. The cascaded dual-loop controller may include an inner high-speed inductor current loop, a pulse-width modulator (PWM) module, and an outer voltage control loop. The inner high-speed inductor current loop may initiate operation of the pulse-width modulator (PWM) module and the outer voltage control loop. The cascaded dual-loop controller may charge and discharge a high-frequency power inductor. The cascaded dual-loop controller may charge and discharge the high-frequency power inductor via a first charging path and a first discharging path in the case of a positive half-sine wave, and via a second charging path and a second discharging path in the case of a negative half-sine wave. The first charging path may extend from the neutral terminal to the negative DC terminal via the high-frequency power inductor and a first bidirectional switch, and the second charging path may extend from the positive DC terminal to the neutral terminal via the high-frequency power inductor and a second bidirectional switch. Meanwhile, the first discharge path may extend from the neutral terminal back to the neutral terminal via the high-frequency power inductor, the output pair filter, and the third bidirectional switch. The second discharge path may extend from the neutral terminal back to the neutral terminal via the third bidirectional switch and the high-frequency power inductor. Another alternative is a three-loop cascade control, where the innermost loop is an inductor current loop, the middle loop is output sinusoidal voltage or current amplitude, and the outermost loop is a loop for maximum power point tracking (MPPT) of the solar power source. The third outermost loop can also be a standard power loop, a minimum fuel consumption (MFC) point, or any other target function to minimize for optimizing system operation. The multilevel T-type inverter may be a three-level inverter, and the number of bidirectional switches may be three.

[0008] In an embodiment, a first bidirectional switch of the plurality of bidirectional switches is located between the power inductor and the positive AC input; a second bidirectional switch of the plurality of bidirectional switches located between the power inductor and the negative AC input; A third bidirectional switch of the plurality of bidirectional switches is located between the power inductor and the output LC filter. The control unit may control the bidirectional switch. The control unit a first charging path is formed by opening the first and third bidirectional switches and closing the second bidirectional switch; a second charging path is formed by opening the second and third bidirectional switches and opening the first bidirectional switch; The first and second discharge paths are configured to be formed by opening the first and second bidirectional switches and closing the third bidirectional switch.

[0009] In an embodiment, the third bidirectional switch comprises first and second pulse width modulation (PWM) switches; The control unit The first PWM switch is operated according to the following equation (8): The second PWM switch is operated according to the following equation (9): It is configured to generate a positive half sine wave by charging a power inductor.

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[0010] In an embodiment, the first bidirectional switch comprises first and second pulse width modulated (PWM) switches; The control unit The first PWM switch of the first bidirectional switch is operated according to the following equation (10): The second PWM switch of the first bidirectional switch is operated according to the following equation (11): The power inductor is configured to generate a negative half sine wave by supplying power to the power inductor.

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[0011] In an embodiment, the control unit is configured such that the control logic signal for driving the switch is based on a basic modulation command expressed by the following equation (1):

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[0012] In an embodiment, the controller is configured to charge the power inductor by operating the first and second PWM switches of the second bidirectional switch according to equation (3) below:

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[0013] In an embodiment, the controller is configured to discharge the power inductor and transfer energy to the grid via the third bidirectional switch; The third bidirectional switch is connected to the first and second bidirectional switches Q 3a and Q 3b Equipped with First bidirectional switch Q 3b is idle, Second bidirectional switch Q 3a operates according to the following equation (4):

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[0014] In an embodiment, the first bidirectional switch is a first Q 1a Switch and second Q 1b a switch; the control unit is configured such that during the negative half sine wave, the inductor is powered from the positive AC terminal via the first bidirectional switch; The first and second PWM switches of the first bidirectional switch operate according to the following equation (6).

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[0015] In an embodiment, the controller is configured to discharge the power inductor and transfer energy to the grid via the third bidirectional switch; The third bidirectional switch is connected to the first and second bidirectional switches Q 3a and Q 3b Equipped with First bidirectional switch Q 3b is idle, Second bidirectional switch Q 3a operates according to the following equation (7):

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[0016] In another embodiment of the method, the controller is configured to perform the operation over an entire sinusoidal period, and the operation is performed by sequentially closing the second bidirectional switch, the third bidirectional switch, the first bidirectional switch, and the third bidirectional switch every quarter of each period.

[0017] Another embodiment of a method is for manufacturing a multilevel t-type inverter for connecting a DC power source to an AC grid, the method comprising: providing a high frequency power inductor; providing a positive terminal for connection to a positive DC voltage source; providing a negative terminal for connection to a negative DC voltage source; providing a grid terminal for connection to an AC grid; providing a neutral terminal for connection to a neutral connection of the AC grid; providing a plurality of bidirectional switches; providing an output LC filter; Each of the plurality of bidirectional switches defines a different current path through the inverter, each path including a high frequency power inductor.

[0018] Another embodiment of a method for connecting a DC power source to an AC grid includes: connecting a high frequency power inductor between the neutral terminal and the common terminal; connecting a first bidirectional switch between a positive terminal and a common terminal of a DC power source; connecting a second bidirectional switch between the negative terminal and the common terminal of the DC power source; connecting a third bidirectional switch between the common terminal and the AC output terminal; generating a positive half sine wave by sequentially closing the first and third bidirectional switches; and generating a negative half-sine wave by sequentially closing the second and third bidirectional switches.

[0019] A method of connecting a DC power source to an AC grid may include using the inverter described above.

[0020] Unless otherwise defined, all technical and / or scientific terms used herein have the meaning commonly understood by those skilled in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, exemplary methods and / or materials are described below. In the event of any discrepancy with the contents of this patent specification, including definitions, the contents of this patent specification shall prevail. Furthermore, the materials, methods, and examples described herein are merely illustrative and are not necessarily intended to limit the present invention. [Brief explanation of the drawings]

[0021] Several embodiments of the present invention will now be described with reference to the accompanying drawings. In particular, when referring to the drawings in detail, it should be noted that the details shown are by way of example only and are presented for the purpose of explaining embodiments of the present invention. In this regard, from a consideration of the description herein in conjunction with the drawings, it will become apparent to one skilled in the art how to practice embodiments of the present invention. [Figure 1A] FIG. 1A is a schematic circuit diagram showing a front-end single-stage boost / buck three-level inverter according to a first embodiment of the present invention. [Figure 1B] FIG. 1B is a schematic circuit diagram showing a front-end single-stage boost / buck three-level inverter according to a first embodiment of the present invention. [Figure 1C] FIG. 1C is a schematic diagram showing a control for operating the inverter of FIG. 1A via the inputs to each of the bidirectional gates. [Figure 2A] FIG. 2A shows the circuit of FIG. 1A switched on for the positive portion of a sine wave input. [Figure 2B] FIG. 2B shows the circuit of FIG. 1A switched on for the positive portion of the sinusoidal input. [Figure 2C] FIG. 2C shows the circuit of FIG. 1A switched on for the positive portion of the sinusoidal input. [Figure 3A]FIG. 3A shows the circuit of FIG. 1A switched on for the negative portion of the sine wave input. [Figure 3B] FIG. 3B shows the circuit of FIG. 1A switched on for the negative portion of the sinusoidal input. [Figure 3C] FIG. 3C shows the circuit of FIG. 1A switched on for the negative portion of the sinusoidal input. [Figure 4] FIG. 4 is a graph showing an outline of the relationship between a DC signal and an AC signal in the inverter of this embodiment. [Figure 5] 1 is a graph showing an outline of the relationship between magnetization and applied magnetic field in the inverter of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention relates to a front-end single-stage buck-boost three-level inverter, and more particularly to using such an inverter to connect a DC power source to an AC grid or directly to a load, such as an electric motor, that requires AC power. This embodiment may provide a multilevel T-type inverter for connecting a DC power source to an AC grid. The inverter includes a high-frequency power inductor, a positive terminal for connecting to a positive DC voltage source, a negative terminal for connecting to a negative DC voltage source, a grid terminal for connecting to an AC grid, a neutral terminal for connecting to a neutral connection of the AC grid, and typically three bidirectional switches, each of which can form a different current path through the high-frequency power inductor. An output LC filter may also be included.

[0023] Before describing at least one embodiment of the present invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction, the arrangement of components and / or methods set forth in the following description and / or drawings and / or examples. The invention may have other embodiments and may be practiced or applied in various ways.

[0024] The operating principle and circuit analysis are explained below. 2 We model and simulate the UI circuit to demonstrate the performance of the proposed circuit in open loop. Finally, we show the T 2 The experimental results of the UI circuit are shown.

[0025] Circuit Topology and Analysis 1A and 1B, which show a first embodiment of the present invention, which is a single-phase three-level T-type universal inverter T 2 The UI 10 is based on a high frequency power inductor 12, a positive voltage DC power supply 14 and a negative voltage DC power supply 16, three bidirectional switches 18, 20, 22, and an output LC filter 24 that is connected to the AC grid. 2 The UI can operate as a single-phase or three-phase inverter in both continuous conduction mode (CCM) and discontinuous conduction mode (DCM).

[0026] High frequency power inductors are capable of operating in the range extending from tens of kilohertz to megahertz, and as used herein the term "high frequency" is intended to include this range.

[0027] A high frequency power inductor 12 has a first end connected to the neutral terminal and a second end connected to a common terminal 19 of three bidirectional switches 18, 20, and 22. The first bidirectional switch 18 is connected between the positive DC power supply input and the common terminal 19. The second bidirectional switch 20 is connected between the negative DC power supply input and the common terminal 19, and the third bidirectional switch 22 is connected between the common terminal 19 and an output filter 24. The output filter 24 is a DC filter consisting of an inductor 25 and a capacitor 27, and is connected between the third bidirectional switch and the AC output to remove DC components in the output.

[0028] The circuits of Figures 1A and 1B are controlled by a controller 21 shown in Figure 1C. This controller has two outputs for each bidirectional gate, controlling the first bidirectional gate via pulse width modulation (PWM) units PWM1a and PWM1b. The second bidirectional gate is controlled via PWM2a and PWM2b. The third bidirectional gate is controlled by the controller via PWM3a and PWM3b.

[0029] The control unit 21 may be a cascade loop control unit that controls the inverter using multiple loops, for example, two loops, three loops, or four loops.

[0030] Reference is now made to Figures 2A-2C, which show different current paths corresponding to a positive half sine wave in the circuit of Figures 1A and 1B. These current paths are established by opening and closing different bidirectional gates using control unit 21, as described below. Each gate corresponds to a specific current path within the inverter, and the current path may take different directions depending on whether it is a positive or negative half cycle.

[0031] T 2 The control circuit of the UI includes a cascaded dual-loop controller 21. The inner high-speed inductor current loop operates a pulse-width modulation (PWM) module, driving the bidirectional switch as described above, while the controller also operates an outer voltage control loop. The operating principle of the positive half-sine wave is T 2 It consists of two parts: charging and discharging the UI high frequency power inductor. The charging path 26 starts from the neutral (N) DC link 28, passes through the power inductor 12, and then passes through the bidirectional switch 20 (Q 2a , Q 2b ) and back to the NDC link 28. To create this charging path, switch 20 is closed and switches 18 and 22 are open (see FIG. 2A). The discharging path 30 maintains the same inductor current direction (clockwise) as the charging path, discharging inductor 12. Discharging is achieved by switching the output bidirectional switch (Q 3a , Q 3b) 22 to output filter 24 and finally back to neutral (see FIG. 2B). To create this discharge path, switch 22 is closed and switches 18 and 20 are open (see FIG. 2B).

[0032] 3A-3C show the charging and discharging paths of a negative half sine wave. Similar to the positive half sine wave shown in FIGS. 2A-2C above, the negative half sine wave 2 The UI power inductor has two paths, one for the charging process and one for the discharging process. The charging path, designated by reference numeral 40 in FIG. 3C, starts from the positive terminal 14 of V1 and is connected to the bidirectional switch 18 (Q 1a , Q 1b ), through high frequency power inductor 12, and back to neutral 28. To create this charge path, switch 18 is closed and switches 20 and 22 are open (see FIG. 3A). The discharge path, designated 42 in FIG. 3C, continues in the direction of the inductor current (clockwise), discharging inductor 12 through neutral 28, through output pair LC filter 24, and back to bidirectional switch (Q 3a , Q 3a ) 22 and back to inductor 12. To create this discharge path, switch 22 is closed and switches 18 and 20 are open (see FIG. 3B).

[0033] Standard NPCs and T 2 Unlike I, T 2 The UI can correspond to a sine wave amplitude that is higher or lower than the voltage of the DC bus.

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[0034] The positive half sine wave begins by charging power inductor 12 to the right. At switch 20, Q 2a and Q 2b It operates according to the following commands:

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[0035] For a negative half sine wave, T 2 The UI works as follows: When charging, the inductor is Q 1a and Q 1b and is powered from the positive terminal of V1 through switch 18, according to the following logic:

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[0036] Discharge of the high frequency power inductor 12 occurs through switch 22 and Q3, where Q 3a is in the idle state (operating as a diode), and Q 3b The control signal is given by the following equation:

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[0037] T 2The UI analysis is performed for two operating modes: continuous mode of operation (CCM) and discontinuous mode of operation (DCM).

[0038] Even under the same algorithm, a more efficient switching method can be used to 1b and Q 2b The switching frequency of the MOSFET is reduced so that both switches operate at the line frequency. A more efficient control logic is as follows:

[0039] For a positive half-cycle sine wave, the Q in switch 20 2a is activated by the following control signal, and the power inductor 12 starts charging to the right.

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[0040] Simulation results Figure 4 shows the results for boost and buck operation. Based on the above analysis, the T 2The UI circuit parameters can be designed under open-loop conditions. The circuit is simulated using the PSIM simulation tool, and the results confirm the analytical results. Figure 5 shows the magnetization versus the applied magnetic field, T 2 This demonstrates the UI's ability to provide harmonic-free voltage and current sine waves. Referring again to Figure 4, a positive supply voltage 52 and a negative supply voltage 54 are shown. Output 50 during boost operation is compared to output 56 during buck operation. The sine wave amplitude can be lower or higher than the DC supply voltage, with boost line 50 exceeding supply voltages 52 and 54. In contrast, buck line 56 is completely within the range of supply voltages 52 and 54.

[0041] It is expected that many related multilevel inverters will be developed during the life of the patent resulting from this application. The scope of the present invention and other technical terms herein is intended to encompass all such innovations. The terms "comprises," "comprising," "includes," "including," "having," and their conjugations mean "including but not limited to." The term "consisting of" means "including and limited to." The term "consisting essentially of" means that a composition, method, or structure may include additional components, steps, and / or parts, provided that the additional components, steps, and / or parts do not materially alter the basic and novel characteristics of the claimed composition, method, or structure.

[0042] As used herein, the singular forms "a," "an," and "the" include plural referents as well, unless the context clearly indicates otherwise.

[0043] It should be understood that certain features of the invention, which are for clarity described in the context of separate embodiments, may also be provided in any combination of those features in a single embodiment, and that the description herein should be construed as if such embodiments were explicitly described herein. Conversely, multiple features of the invention, which are for brevity described in the context of a single embodiment, may also be provided separately or in any suitable subcombination, or with respect to other described embodiments as appropriate. The description herein should be construed as if such separate embodiments, subcombinations, and modified embodiments were explicitly described herein. Certain features described in the context of various embodiments should not be construed as essential to that embodiment, unless the particular embodiment is inoperable without that element.

[0044] While the present invention has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the spirit and broad scope of the appended claims.

[0045] It is the applicant's intention that all publications, patents, and patent applications mentioned in this specification be incorporated herein by reference in their entirety to the same extent as if each individual publication, patent, and patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application should not be construed as an admission that such reference is available as prior art to the present invention, nor should it necessarily be construed as limiting, to the extent that section headings are used. In addition, the priority document of this application, if any, is incorporated herein by reference in its entirety.

Claims

1. A multi-level t-type inverter for connecting a DC power supply to an AC grid, wherein the multi-level t-type inverter is High-frequency power inductor and A positive terminal for connecting to a positive DC voltage source, A negative terminal for connecting to a negative DC voltage source, A grid terminal for connecting to the AC grid, A neutral terminal for connecting to the neutral connection section of the AC grid, A plurality of bidirectional switches, each of which defines a different current path through the inverter, and each path is equipped with the high-frequency power inductor, It includes an output LC filter, Multi-level T-type inverter.

2. Equipped with a cascade loop control unit, or The first bidirectional switch among the plurality of bidirectional switches is located between the high-frequency power inductor and the positive AC input, the second bidirectional switch among the plurality of bidirectional switches is located between the high-frequency power inductor and the negative AC input, and the third bidirectional switch among the plurality of bidirectional switches is located between the high-frequency power inductor and the output LC filter. The multi-level t-type inverter according to claim 1.

3. The cascade loop control unit is Internal high-speed inductor current loop, A pulse width modulator (PWM) module, A voltage control loop, The multi-level t-type inverter according to claim 2.

4. The cascade loop control unit is a three-loop control unit, and further comprises loops, or The internal high-speed inductor current loop is configured to initiate the operation of the pulse-width modulator (PWM) module and the voltage control loop in a further loop, wherein the further loop is one of the following: a power loop, a maximum power point tracking (MPPT), a minimum fuel consumption point (MFC), and a minimize target function, or The cascade loop control unit is configured to charge and discharge the high-frequency power inductor. The multi-level t-type inverter according to claim 3.

5. The further loop is one of the group consisting of a power loop, a maximum power point tracking (MPPT), a minimum fuel consumption point (MFC), and a minimization target function, or The cascade loop control unit is configured to charge and discharge the high-frequency power inductor via the first charging path and the first discharging path in the case of a positive half-sine wave, and to charge and discharge the second charging path and the second discharging path in the case of a negative half-sine wave, or The first charging path extends from the neutral terminal to the negative AC terminal via the high-frequency power inductor and the second bidirectional switch among the plurality of bidirectional switches, or The second charging path extends from the neutral AC terminal to the negative AC terminal via the high-frequency power inductor and the second bidirectional switch among the plurality of bidirectional switches, or The first discharge path extends from the neutral AC terminal, through the high-frequency power inductor, the output LC filter, and the third bidirectional switch among the plurality of bidirectional switches, and returns to the neutral AC terminal. The second discharge path extends from the neutral AC terminal back to the neutral AC terminal via the third bidirectional switch among the plurality of bidirectional switches and the high-frequency power inductor. The multi-level t-type inverter according to claim 4.

6. The first bidirectional switch among the plurality of bidirectional switches is located between the high-frequency power inductor and the positive AC input, The second bidirectional switch among the plurality of bidirectional switches is located between the high-frequency power inductor and the negative AC input. The third bidirectional switch among the plurality of bidirectional switches is located between the high-frequency power inductor and the output LC filter. The multi-level t-type inverter includes a control unit for the bidirectional switch, The control unit, The first charging path is formed by opening the first and third bidirectional switches and closing the second bidirectional switch. A second charging path is formed by opening the second and third bidirectional switches and then opening the first bidirectional switch. The first and second discharge paths are formed by opening the first and second bidirectional switches and closing the third bidirectional switch. It is configured in such a way. The multi-level t-type inverter according to claim 1.

7. The third bidirectional switch comprises first and second pulse-width modulation (PWM) switches, and the control unit is configured to generate a positive half-sine wave by operating the first PWM switch according to the following equation (8) and the second PWM switch according to the following equation (9) to charge the high-frequency power inductor, or, The control unit is configured such that the control logic signal for driving the bidirectional switch is based on a basic modulation command represented by the following formula (1): The multi-level t-type inverter according to claim 6. [Math 1] 【Number 2】 [Math 3] Here, α(t) is [Math 4]

8. The first bidirectional switch comprises first and second pulse width modulation (PWM) switches, The control unit, The first PWM switch of the first bidirectional switch is operated according to the following equation (10): The second PWM switch of the first bidirectional switch is operated according to the following equation (11): The high-frequency power inductor is configured to generate a negative half-sinusoidal wave by supplying power to it. The multi-level t-type inverter according to claim 6. [Math 5] [Math 6]

9. The multi-level t-type inverter comprises a control unit, The control unit is configured to charge the high-frequency power inductor by operating the first and second PWM switches of the second bidirectional switch among the plurality of bidirectional switches according to the following equation (3): The multi-level t-type inverter according to claim 1. [Number 7]

10. The control unit is configured to discharge the high-frequency power inductor and transmit energy to the AC grid via the third bidirectional switch among the plurality of bidirectional switches. The third bidirectional switch comprises a first PWM switch Q3a and a second PWM switch Q3b. The second PWM switch Q3b is in an idle state. The first PWM switch Q3a operates according to the following equation (4): The multi-level t-type inverter according to claim 9. [Number 8] Here, [Number 9] and, [Number 10]

11. The first bidirectional switch among the plurality of bidirectional switches comprises a first PWM switch Q1a and a second PWM switch Q1b. The control unit is configured such that, during a negative half-sinusoidal wave, the high-frequency power inductor is supplied with power from the positive AC terminal via the first bidirectional switch. The first and second PWM switches of the first bidirectional switch operate according to the following equation (6): The multi-level t-type inverter according to claim 10. [Math 11]

12. The control unit is configured to discharge the high-frequency power inductor and transmit energy to the AC grid via the third bidirectional switch. The third bidirectional switch comprises a first PWM switch Q3a and a second PWM switch Q3b. The second PWM switch Q3b is in an idle state. The first PWM switch Q3a operates according to the following equation (7): The multi-level t-type inverter according to claim 11. [Number 12]

13. The control unit is configured to operate throughout the entire sinusoidal period, The operation described above is performed by a sequence of closing the second bidirectional switch, the third bidirectional switch, the first bidirectional switch, and the third bidirectional switch in that order, every quarter of each cycle. The multi-level t-type inverter according to claim 6.

14. A method for manufacturing a multi-level t-type inverter for connecting a DC power supply to an AC grid, wherein the method is: By providing a high-frequency power inductor, A positive terminal is provided for connection to a positive DC voltage source, A negative terminal is provided for connection to a negative DC voltage source, To provide a grid terminal for connecting to the AC grid, A neutral terminal is provided for connecting to the neutral connection section of the AC grid, By providing multiple bidirectional switches, This includes providing an output LC filter, Each of the plurality of bidirectional switches defines a different current path through the inverter, and each path includes the high-frequency power inductor. method.

15. A method for connecting a DC power supply to an AC grid, wherein the method is Connecting a high-frequency power inductor between the neutral terminal and the common terminal, The first bidirectional switch is connected between the positive terminal of the DC power supply and the common terminal, The second bidirectional switch is connected between the negative terminal of the DC power supply and the common terminal, A third bidirectional switch is connected between the common terminal and the AC output terminal, By sequentially closing the first and third bidirectional switches, a positive half-sine wave is generated, The method includes generating a negative half-sine wave by sequentially closing the second and third bidirectional switches, method.

16. This includes controlling switching using an internal high-speed inductor current loop, a pulse-width modulator (PWM) module, and a voltage control loop. The method according to claim 15.

17. This includes using a further loop, the further loop being one of a group consisting of a power loop, a maximum power point tracking (MPPT), a minimum fuel consumption point (MFC), and a minimization target function. The method according to claim 16.

18. The internal high-speed inductor current loop is configured to initiate the operation of the pulse width modulator (PWM) module and the voltage control loop together with the further loop. The method according to claim 17.

19. The third bidirectional switch comprises first and second pulse-width modulation (PWM) switches, and the method includes generating a positive half-sine wave by charging the high-frequency power inductor by operating the first PWM switch according to the following equation (8) and the second PWM switch according to the following equation (9), or The first bidirectional switch comprises first and second pulse-width modulation (PWM) switches, and the method includes generating a positive half-sine wave by supplying power to the high-frequency power inductor by operating the first PWM switch of the first bidirectional switch according to the following equation (10) and operating the second PWM switch of the first bidirectional switch according to the following equation (11), or The method includes providing control logic signals for driving the first, second and third bidirectional switches, the control logic signals being based on a basic modulation command represented by the following formula (1): The method according to claim 16. [Number 13] [Number 14] [Number 15] [Number 16] [Number 17] Here, α(t) is [Number 18]

20. The first and second PWM switches of the second bidirectional switch are operated according to the following formula (3) to charge the high-frequency power inductor, The method according to claim 19. [Number 19]

21. Discharging the high-frequency power inductor to transmit energy to the AC grid via the third bidirectional switch, The third bidirectional switch comprises a first PWM switch Q3a and a second PWM switch Q3b. The second PWM switch Q3b is in an idle state. The first PWM switch Q3a operates according to the following equation (4): The method according to claim 20. [Number 20] Here, [Number 21] and, [Number 22]

22. The first bidirectional switch comprises a first PWM switch Q1a and a second PWM switch Q1b. The method includes supplying power from the positive AC terminal to the high-frequency power inductor via the first bidirectional switch during a negative half-sinusoidal wave. The first and second PWM switches of the first bidirectional switch operate according to the following equation (6): The method according to claim 21. [Number 23]

23. comprising discharging the high-frequency power inductor and transmitting energy to the AC grid via the third bidirectional switch, The third bidirectional switch comprises a first PWM switch Q3a and a second PWM switch Q3b. The second PWM switch Q3b is in an idle state. The first PWM switch Q3a operates according to the following equation (7): The method according to claim 22. [Number 24]

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