High-frequency LCL filter circuit

Abstract

The utility model provides a high-frequency LCL filter circuit, which is characterized in that a first end of a first inductor is electrically connected with an A-phase line of a three-phase inverter, a second end of the first inductor is electrically connected with a second inductor, a first end of a third inductor is electrically connected with a B-phase line of the three-phase inverter, and a second end of the third inductor is electrically connected with a fourth inductor; the first end of the fifth inductor is electrically connected with a C-phase line of the three-phase inverter, the second end of the fifth inductor is electrically connected with the sixth inductor, the first end of the first capacitor and the first end of the fourth capacitor are electrically connected with the second end of the first inductor, the first end of the second capacitor and the first end of the fifth capacitor are electrically connected with the second end of the third inductor, and the second end of the third inductor is electrically connected with the fourth inductor. The first end of the third capacitor and the first end of the sixth capacitor are electrically connected with the second end of the fifth inductor, the first end of the first electronic switch is electrically connected with the second end of the first capacitor, the second end of the first electronic switch is electrically connected with the N line of the three-phase inverter and the second electronic switch, and the second inductor, the fourth inductor and the sixth inductor are connected into a power grid.

Description

Technical Field

[0001] The utility model relates to the technical field of filter circuits, in particular to a high-frequency LCL filter circuit. Background Art

[0002] The traditional three-phase three-wire filter circuit uses LCL circuit to filter high-frequency current by phase-to-phase commutation; the traditional three-phase four-wire filter circuit uses midpoint extraction to filter high-frequency current on the neutral line. For energy storage inverters, it is necessary to realize the three-phase three-wire working mode of grid connection when the grid is powered, and to realize the three-phase four-wire working mode of off-grid after the grid loses power. The existing traditional three-phase three-wire filter circuit using LCL circuit cannot meet the above two working modes at the same time.

[0003] In view of this, it is necessary to provide a new high-frequency LCL filter circuit to overcome the above-mentioned defects. Utility Model Content

[0004] The utility model aims to provide a high-frequency LCL filter circuit, which can realize a three-phase three-wire working mode connected to the grid when the grid is powered, and can also realize a three-phase four-wire working mode off the grid after the grid loses power.

[0005] In order to achieve the above object, the utility model provides a high-frequency LCL filter circuit, including: a three-phase inverter and a high-frequency LCL filter, wherein the high-frequency LCL filter includes a first inductor L1, a second inductor L2, a third inductor L3, a fourth inductor L4, a fifth inductor L5, a sixth inductor L6, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a first electronic switch SCR1 and a second electronic switch SCR2;

[0006] The three-phase inverter is connected to a DC power supply, a first end of the first inductor L1 is electrically connected to a phase A line of the three-phase inverter, a second end of the first inductor L1 is electrically connected to a second inductor L2, a first end of the third inductor L3 is electrically connected to a phase B line of the three-phase inverter, a second end of the third inductor L3 is electrically connected to a fourth inductor L4, a first end of the fifth inductor L5 is electrically connected to a phase C line of the three-phase inverter, and a second end of the fifth inductor L5 is electrically connected to a sixth inductor L6,

[0007] The first end of the first capacitor C1 and the first end of the fourth capacitor C4 are electrically connected to the second end of the first inductor L1, the first end of the second capacitor C2 and the first end of the fifth capacitor C5 are electrically connected to the second end of the third inductor L3, the first end of the third capacitor C3 and the first end of the sixth capacitor C6 are electrically connected to the second end of the fifth inductor L5, the first end of the first electronic switch SCR1 is electrically connected to the second end of the first capacitor C1, the second end of the first electronic switch SCR1 is electrically connected to the N line of the three-phase inverter and the second electronic switch SCR2, and the second inductor L2, the fourth inductor L4 and the sixth inductor L6 are respectively connected to the A phase line, the B phase line and the C phase line of the power grid.

[0008] Preferably, the three-phase inverter includes capacitor C7, capacitor C8 and a bridge three-phase inverter circuit unit, the bridge three-phase inverter circuit unit is composed of switch S1, switch S2, switch S3, switch S4, switch S5 and switch S6, the first end of the capacitor C7 is electrically connected to the positive electrode of the DC power supply and the bridge three-phase inverter circuit unit, the second end of the capacitor C7 is electrically connected to the first end of the capacitor C8, and the second end of the capacitor C8 is electrically connected to the negative electrode of the DC power supply and the bridge three-phase inverter circuit unit.

[0009] Compared with the prior art, the beneficial effect is that when the grid is powered, the first electronic switch SCR1 and the second electronic switch SCR2 are cut off, and the high-frequency LCL filter circuit works in a three-phase three-wire mode without a neutral line channel. The high-frequency LCL filter circuit adopts an SVPWM modulation mode to realize a grid-connected current source control mode;

[0010] When the power grid loses power, the first electronic switch SCR1 and the second electronic switch SCR2 are closed, and the high-frequency LCL filter circuit works in a three-phase four-wire mode. The high-frequency LCL filter circuit adopts an SPWM modulation mode. The high-frequency LCL filter can filter out the high-frequency current of the N line, thereby realizing the DC power supply to the user and realizing the off-grid voltage source control mode.

[0011] Other features and advantages of the utility model will be stated in the following description, and some will be apparent from the description, or can be understood through the implementation of the utility model. The features and advantages of the utility model can be realized and obtained by the elements and combinations specifically pointed out in the attached application scope. These and other features of the utility model will become more clearly understood according to the following description and the attached claims, or can be understood through the implementation of the embodiments described in the utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 The utility model provides a circuit diagram of a high-frequency LCL filter circuit. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution and beneficial technical effect of the utility model clearer, the utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific implementation methods described in this specification are only for explaining the utility model, and are not intended to limit the utility model.

[0015] It should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0016] It should also be noted that, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this utility model can be determined according to the specific circumstances.

[0017] In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first", "second", and "third" may explicitly or implicitly include one or more of the features. In addition, the meaning of "multiple" and "several" refers to two or more, unless otherwise clearly and specifically defined.

[0018] See also Figure 1The utility model provides a high-frequency LCL filter circuit, including: a three-phase inverter and a high-frequency LCL filter, wherein the high-frequency LCL filter includes a first inductor L1, a second inductor L2, a third inductor L3, a fourth inductor L4, a fifth inductor L5, a sixth inductor L6, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a first electronic switch SCR1 and a second electronic switch SCR2;

[0019] The three-phase inverter is connected to a DC power supply, a first end of the first inductor L1 is electrically connected to a phase A line of the three-phase inverter, a second end of the first inductor L1 is electrically connected to a second inductor L2, a first end of the third inductor L3 is electrically connected to a phase B line of the three-phase inverter, a second end of the third inductor L3 is electrically connected to a fourth inductor L4, a first end of the fifth inductor L5 is electrically connected to a phase C line of the three-phase inverter, and a second end of the fifth inductor L5 is electrically connected to a sixth inductor L6,

[0020] The first end of the first capacitor C1 and the first end of the fourth capacitor C4 are electrically connected to the second end of the first inductor L1, the first end of the second capacitor C2 and the first end of the fifth capacitor C5 are electrically connected to the second end of the third inductor L3, the first end of the third capacitor C3 and the first end of the sixth capacitor C6 are electrically connected to the second end of the fifth inductor L5, the first end of the first electronic switch SCR1 is electrically connected to the second end of the first capacitor C1, the second end of the first electronic switch SCR1 is electrically connected to the N line of the three-phase inverter and the second electronic switch SCR2, and the second inductor L2, the fourth inductor L4 and the sixth inductor L6 are respectively connected to the A phase line, the B phase line and the C phase line of the power grid.

[0021] When the grid is powered, the first electronic switch SCR1 and the second electronic switch SCR2 are cut off. At this time, the high-frequency LCL filter circuit works in a three-phase three-wire mode without a neutral line channel. The high-frequency LCL filter circuit adopts an SVPWM modulation mode to realize a grid-connected current source control mode.

[0022] When the power grid loses power, the first electronic switch SCR1 and the second electronic switch SCR2 are closed, and the high-frequency LCL filter circuit works in a three-phase four-wire mode. The high-frequency LCL filter circuit adopts an SPWM modulation mode. The high-frequency LCL filter can filter out the high-frequency current of the N line, thereby realizing the DC power supply to the user and realizing the off-grid voltage source control mode.

[0023] In a preferred embodiment, the three-phase inverter includes a capacitor C7, a capacitor C8 and a bridge three-phase inverter circuit. The bridge three-phase inverter circuit unit is composed of a switch S1, a switch S2, a switch S3, a switch S4, a switch S5 and a switch S6. The first end of the capacitor C7 is electrically connected to the positive electrode of the DC power supply and the bridge three-phase inverter circuit unit, the second end of the capacitor C7 is electrically connected to the first end of the capacitor C8, and the second end of the capacitor C8 is electrically connected to the negative electrode of the DC power supply and the bridge three-phase inverter circuit unit.

[0024] In this way, the three-phase inverter converts the DC power supply into three three-phase AC power supplies with the same frequency, equal amplitude and 120° phase difference. The main function of the capacitor C7 and the capacitor C8 is to filter the voltage ripple of the input circuit and stabilize the current and voltage when the load changes.

[0025] The present invention is not limited to what is described in the specification and implementation modes, and therefore, additional advantages and modifications can be easily realized by those familiar with the art. Therefore, without departing from the spirit and scope of the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details, representative devices, and illustrative examples shown and described herein.

Claims

1. A high frequency LCL filter circuit, characterized in that: include: A three-phase inverter and a high-frequency LCL filter, wherein the high-frequency LCL filter comprises a first inductor L1, a second inductor L2, a third inductor L3, a fourth inductor L4, a fifth inductor L5, a sixth inductor L6, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a first electronic switch SCR1 and a second electronic switch SCR2; The three-phase inverter is connected to a DC power supply, a first end of the first inductor L1 is electrically connected to a phase A line of the three-phase inverter, a second end of the first inductor L1 is electrically connected to a second inductor L2, a first end of the third inductor L3 is electrically connected to a phase B line of the three-phase inverter, a second end of the third inductor L3 is electrically connected to a fourth inductor L4, a first end of the fifth inductor L5 is electrically connected to a phase C line of the three-phase inverter, and a second end of the fifth inductor L5 is electrically connected to a sixth inductor L6, The first end of the first capacitor C1 and the first end of the fourth capacitor C4 are electrically connected to the second end of the first inductor L1, the first end of the second capacitor C2 and the first end of the fifth capacitor C5 are electrically connected to the second end of the third inductor L3, the first end of the third capacitor C3 and the first end of the sixth capacitor C6 are electrically connected to the second end of the fifth inductor L5, the first end of the first electronic switch SCR1 is electrically connected to the second end of the first capacitor C1, the second end of the first electronic switch SCR1 is electrically connected to the N line of the three-phase inverter and the second electronic switch SCR2, and the second inductor L2, the fourth inductor L4 and the sixth inductor L6 are respectively connected to the A phase line, the B phase line and the C phase line of the power grid.

2. The high-frequency LCL filter circuit according to claim 1, characterized in that: The three-phase inverter includes a capacitor C7, a capacitor C8 and a bridge three-phase inverter circuit. The bridge three-phase inverter circuit unit is composed of a switch S1, a switch S2, a switch S3, a switch S4, a switch S5 and a switch S6. The first end of the capacitor C7 is electrically connected to the positive electrode of the DC power supply and the bridge three-phase inverter circuit unit, the second end of the capacitor C7 is electrically connected to the first end of the capacitor C8, and the second end of the capacitor C8 is electrically connected to the negative electrode of the DC power supply and the bridge three-phase inverter circuit unit.

Images