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Two-stage non-isolation photovoltaic grid-connected inverter and control method thereof

A non-isolated, inverter technology, applied in photovoltaic power generation, control/regulation systems, instruments, etc.

Active Publication Date: 2016-01-20
HOHAI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method requires two bus capacitor branches, and the withstand voltage of the second bus capacitor must be greater than the peak value of the grid voltage
On the other hand, the topology of the grid-connected inverter in this scheme is a traditional bridge inverter, so when using unipolar SPWM modulation, there is a problem of leakage current

Method used

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  • Two-stage non-isolation photovoltaic grid-connected inverter and control method thereof
  • Two-stage non-isolation photovoltaic grid-connected inverter and control method thereof
  • Two-stage non-isolation photovoltaic grid-connected inverter and control method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0093] The two-stage non-isolated photovoltaic grid-connected inverter described in Embodiment 1 adopts the low-voltage power transmission branch 22 of the first structure, and the full-bridge power conversion circuit 2 includes six working modes:

[0094] Mode 1: the first power switch tube of the full-bridge power conversion circuit 2 S 1 , the fourth power switch tube S 4 and the fifth power switch tube S 5 turn on, the other power switch tubes in the full-bridge power conversion circuit 2 are turned off, and the incoming current flows through the first power switch tubes in sequence S 1 , the first filter inductor L f1 , power grid u g , the fourth power switch tube S 4 ; The bridge arm voltage of the full-bridge power conversion circuit 2 is the first DC bus capacitor C dc1 and the second DC link capacitor C dc2 sum of voltages.

[0095] Mode 2: the fifth power switch tube of the full-bridge power conversion circuit 2 S 5 and the fourth power switch tube...

Embodiment 2

[0131] The two-stage non-isolated photovoltaic grid-connected inverter described in Embodiment 2 adopts the low-voltage power transmission branch 22 of the first structure, and the full-bridge power conversion circuit 2 includes six working modes:

[0132] Mode 1: the first power switch tube of the full-bridge power conversion circuit 2 S 1 , the fourth power switch tube S 4 and the fifth power switch tube S 5 turn on, the other power switch tubes in the full-bridge power conversion circuit 2 are turned off, and the incoming current flows through the fourth power switch tube in sequence S 4 , power grid u g , the first filter inductor L f1 , the first power switch tube S 1 ; The bridge arm voltage of the full-bridge power conversion circuit 2 is the first DC bus capacitor C dc1 and the second DC link capacitor C dc2 sum of voltages.

[0133] Mode 2: the fifth power switch tube of the full-bridge power conversion circuit 2 S 5 and the fourth power switch tube ...

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Abstract

The invention discloses a two-stage non-isolation photovoltaic grid-connected inverter. The two-stage non-isolation photovoltaic grid-connected inverter comprises a first direct current bus capacitor, a second direct current bus capacitor, a direct current power conversion circuit, and a full bridge power conversion circuit, the first direct current bus capacitor is connected with a photovoltaic assembly string and an input terminal of the direct current power conversion circuit in sequence, the second direct current bus capacitor is connected with an output terminal of the direct current power conversion circuit, the first direct current bus capacitor and the second direct current bus capacitor are connected in series and then connected with an input terminal of the full bridge power conversion circuit, and an output terminal of the full bridge power conversion circuit is externally connected with a power grid. The invention also discloses a control method thereof. According to the two-stage non-isolation photovoltaic grid-connected inverter and the control method thereof, the voltage stress of the direct current bus capacitors is reduced, only a part of power passes through the direct current power conversion circuit, the power conversion stage number is small, and the power loss is small; double-buck topology is employed, hidden risks of gating of bridge arms can be prevented, and the reliability is high; freewheeling is realized via an independent diode, a power switch tube can employ an MOSFET, and the conversion efficiency of the grid-connected inverter can be improved.

Description

technical field [0001] The invention relates to a two-stage non-isolated photovoltaic grid-connected inverter and a control method thereof, belonging to the technical field of power electronic converters. Background technique [0002] With the increasingly severe energy crisis and environmental pollution, new energy power generation technologies such as solar energy, wind energy, and fuel cells have become the focus of attention and research around the world. According to whether the new energy power generation system is connected to the public grid, it can be divided into two modes: grid-connected operation and independent operation. Among them, grid-connected operation is the most common way of new energy power generation application, and grid-connected inverter is a key component in the new energy grid-connected system, and it is of great significance to improve its conversion efficiency. [0003] In the traditional two-stage photovoltaic grid-connected inverter, the out...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/5387H02M3/155
CPCY02E10/56
Inventor 张犁吴红飞赵晋泉
Owner HOHAI UNIV
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