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Inverter and application circuit in three-phase system

An inverter and bridge circuit technology, applied in the field of transformerless photovoltaic grid-connected inverter and its application circuit in three-phase system, can solve the problems of complex control method, difficulty in midpoint balance control, etc.

Active Publication Date: 2012-08-01
SUNGROW POWER SUPPLY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The inverter actually works at three levels, and if it is to ensure that the freewheeling circuit potential described in the patent is half of the battery voltage, the midpoint potential between the two capacitors must be guaranteed to be half One of the battery voltages, this kind of neutral point balance control is difficult in actual operation and requires complex control methods

Method used

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  • Inverter and application circuit in three-phase system

Examples

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no. 1 example

[0117] see Figure 4 , The embodiment of the present invention provides an inverter, including a DC / DC converter, capacitors C1, C2, three power switch tubes T1, T2, T7 connected in series, and an H-bridge circuit.

[0118] The input end and the ground end of the DC / DC converter are respectively connected to two ends of the DC power supply.

[0119] The capacitor C2 is connected between the positive and negative output terminals of the DC power supply, and the capacitor C1 is connected between the positive output terminal of the DC / DC converter and the negative output terminal of the DC power supply.

[0120] A diode D1, D2, D7 is respectively anti-parallel connected to the power switch tubes T1, T2, T7, the collector of the power switch tube T1 is connected to the positive output terminal of the DC power supply, and the collector of the power switch tube T7 is connected to the DC / DC converter The positive output terminal of the power switch tube T1 is connected to the collec...

no. 2 example

[0160] Figure 12 It is the main circuit of the second embodiment of the present invention, which has the same components as the above-mentioned first embodiment. Dual topology of an embodiment. Its specific structure is as follows.

[0161] Both the input terminal and the ground terminal of the DC / DC converter are connected to the positive output terminal of the DC power supply.

[0162] The capacitor C2 is connected between the positive and negative output terminals of the DC power supply, and the capacitor C1 is connected between the negative output terminal of the DC / DC converter and the positive output terminal of the DC power supply.

[0163] The power switch tubes T1, T2, and T7 are respectively anti-parallel connected with a diode D1, D2, D7, the emitter of the power switch tube T7 is connected to the negative output terminal of the DC / DC converter, and the emitter of the power switch tube T2 is connected to the DC power supply The negative output terminal of the po...

no. 3 example

[0193] see Figure 19 , the difference between this embodiment and the first embodiment is that one power switch tube T2 is missing, and the structures of other parts are the same.

[0194] see Figure 20a to Figure 20h , the working mode analysis of the inverter in this embodiment is as follows:

[0195] Mode H1: The switching tubes T3, T6, and T7 are turned on, and the rest are turned off. Current through: DC+→T7→D2→T3→L1→Vgrid→L2→T6→PV-, bridge arm output voltage Vab=V1.

[0196] Mode H3: Switch tubes T4, T5, and T7 are turned on, and the rest are turned off. Current through: DC+→T7→D2→T5→L2→Vgrid→L1→T4→PV-, bridge arm output voltage Vab=-V1.

[0197] Mode H5: The switch tubes T1, T3, and T6 are turned on, and the rest are turned off. The current passes through: PV+→T1→T3→L1→Vgrid→L2→T6→PV-, the bridge arm output voltage Vab=V2.

[0198] Mode H6: The switch tubes T1, T3, and T6 are turned on, and the rest are turned off. The current passes through: PV-→D6→L2→Vgrid→L1...

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Abstract

The embodiment of the invention discloses an inverter. The collector of a power switching tube T1 is connected to the positive output terminal of a DC power supply; the emitter of the T1 and the collector of a power switching tube T2 are connected to one input terminal of an H bridge circuit, the other input terminal of the H bridge circuit is connected with the negative output terminal of the DC power supply, and the two output terminals of the H bridge circuit are respectively connected to a power grid; each power switching tube is inversely connected in parallel with a diode; a DC / DC converter is connected with two ends of the DC power supply; a capacitor C2 is connected between the positive and the negative output terminals of the DC power supply; a capacitor C1 is connected between the positive output terminal of the DC / DC converter and the negative output terminal of the DC power supply; the T2 is connected with the emitter of a power switching tube T7; and the collector of the T7 is connected with the positive output terminal of the DC / DC converter. The embodiment of the invention also discloses a dual topology of the inverter and other two inverters developed from the dual topology, and provides an application circuit of the four inverters, which is in the three-phase system. The embodiment of the invention has the advantages that high efficiency of the inverters are ensured, current leakage is reduced, and the problem of midpoint balance control to multiple levels is avoided.

Description

technical field [0001] Embodiments of the present invention relate to an inverter and its application circuit, specifically a transformerless photovoltaic grid-connected inverter and its application circuit in a three-phase system. Background technique [0002] According to the different application occasions and control methods of the inverter, it can be divided into off-grid inverter and grid-connected inverter. In the grid-connected inverter, it can be divided into transformer-isolated inverter according to whether it has a transformer or not. inverters and transformerless inverters. Due to the advantages of simple system structure, high efficiency, small size and low cost, the transformerless inverter has been developed rapidly. It has become the mainstream of photovoltaic medium and small power. [0003] The existing commonly used transformerless inverter is H4 topology, which is an H-bridge circuit composed of 4 switching devices, such as figure 1 As shown, the phot...

Claims

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Application Information

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IPC IPC(8): H02M7/483
CPCH02M7/5388H02M1/007H02M1/123
Inventor 汪洪亮
Owner SUNGROW POWER SUPPLY CO LTD
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