20kW three-level photovoltaic grid-connected inverter

An inverter and three-level technology, applied in photovoltaic power generation, adjusting electrical variables, instruments, etc., can solve the problems of small enough device volume, large harmonic components, low conversion efficiency, etc., to achieve reduced volume, harmonic The effect of content reduction and conversion efficiency improvement

Inactive Publication Date: 2018-02-06
由国峰
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  • Abstract
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  • Application Information

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Problems solved by technology

[0003] In order to overcome the problems of low conversion efficiency, large harmonic components, and insufficient device volume, the present invention proposes a 20kW three-level photovoltaic grid-connected inverter

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  • 20kW three-level photovoltaic grid-connected inverter
  • 20kW three-level photovoltaic grid-connected inverter
  • 20kW three-level photovoltaic grid-connected inverter

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Embodiment Construction

[0013] specific implementation plan

[0014] figure 1 Among them, the main circuit topology of the system is mainly composed of Boost, DC link, I-type NPC inverter, grid-connected filter, common-mode filter and grid-connected switch. Among them, the Boost step-up module adopts the Boost three-level DC converter, and the voltage stress of the switch tube is half of that of the ordinary Boost converter; the inverter part adopts the I-type NPC topology, and adds a balance resistor to ensure the reliability of the inner tube. Shutdown and equalization of internal and external tubes; the output filter is divided into LC grid-connected filter and common mode filter. Share the common-mode voltage output by the inverter to reduce the common-mode voltage at the grid-connected end. The latter three-level inverter adopts the current and voltage double closed-loop structure to realize the decoupling control of active power and reactive power. On the one hand, it realizes active current ...

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Abstract

The invention discloses a 20kW three-level photovoltaic grid-connected inverter. The inverter comprises three portions including a 20kW three-level photovoltaic grid-connected inverter main circuit, aBoost control system, and an NPC inverter control system. The system employs a design without a step-up transformer, the Boost portion employs an interleaved parallel structure, the inversion portionemploys an I-type NPC three-level structure, and parameters of a system layer are designed. Aiming at the problem of neutral-point voltage balance of the NPC topology structure, the neutral-point voltage is adjusted through change of the charging and discharging time of upper and lower capacitors in a Boost circuit, a neural-point potential balance control algorithm based on a bus capacitance neural-point charge is combined, and test verification is performed. The control of the inverter employs power grid voltage orientation vector control, and the reliability of the apparatus is verified through the test.

Description

Technical field [0001] The invention relates to a photovoltaic grid-connected inverter, in particular to a 20kW three-level photovoltaic grid-connected inverter. Background technique [0002] In recent years, distributed power generation systems have developed rapidly, and photovoltaic grid-connected power generation systems are the most typical type of them, and have received more and more attention in recent years. Compared with traditional two-level inverters, NPC three-level photovoltaic inverters have obvious advantages such as reduced harmonic components, lower component withstand voltage levels, and smaller device volumes, making them very suitable for applications in distributed energy systems. In order to improve the conversion efficiency, a transformerless three-level inverter is designed, which is mainly composed of a Boost circuit, an I-type NPC inverter circuit and a control circuit. Boost control adopts the control strategy combining MPPT and mid-point voltage...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M3/158H02M7/5387H02M1/12H02J3/38
CPCH02J3/01H02J3/385H02M3/1582H02M7/5387Y02E10/56
Inventor 由国峰
Owner 由国峰
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