Common-mode voltage suppression method for non-isolated T-shaped tri-level photovoltaic grid-connected inverter

A common-mode voltage, three-level technology, applied in the field of solar photovoltaic power generation, can solve problems such as endangering equipment and personnel safety, conducting and radiating interference, increasing network current harmonics and loss, etc.

Inactive Publication Date: 2015-07-15
XIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Larger-amplitude common-mode currents may cause conduction and radiation interference, increase harmonics and losses of incoming current, and even endanger the safety of equipment and personnel

Method used

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  • Common-mode voltage suppression method for non-isolated T-shaped tri-level photovoltaic grid-connected inverter
  • Common-mode voltage suppression method for non-isolated T-shaped tri-level photovoltaic grid-connected inverter
  • Common-mode voltage suppression method for non-isolated T-shaped tri-level photovoltaic grid-connected inverter

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Embodiment Construction

[0070] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0071] Such as figure 1 As shown, the circuit structure of the non-isolated T-type three-level photovoltaic grid-connected inverter includes the first parasitic capacitance C PV1 , the first parasitic capacitance C PV1 One end is connected to the ground, the first parasitic capacitance C PV1 The other end of the photovoltaic array is connected to the output voltage U dc The positive pole of the DC bus capacitor C 1 positive pole of the first switch tube S a1 The collector of the second switch tube S b1 The collector of the third switch tube S c1 The collector; PV array output voltage U dc The negative poles of are respectively connected with the second parasitic capacitance C PV2 One end of the DC bus capacitor C 2 The negative electrode of the fourth switching tube S a4 The emitter of the fifth switch tube S b4 emitter, the sixth ...

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Abstract

The invention discloses a common-mode voltage suppression method for a non-isolated T-shaped tri-level photovoltaic grid-connected inverter. The method comprises steps as follows: voltage of an upper capacitor C1 of a direct-current bus and voltage of a lower capacitor C2 of the direct-current bus are collected in real time to obtain an absolute value dUdc of voltage difference of the upper capacitor C1 and the lower capacitor C2 of the direct-current bus; whether dUdc is larger than dUref and whether Uc1 is larger than Uc2 are judged, so that a large and medium zero vector synthesis method, a large, medium and small vector synthesis method or a large and large zero vector synthesis method is selected and utilized for modulating the non-isolated T-shaped tri-level photovoltaic grid-connected inverter. The three vector synthesis methods are adopted to modulate the non-isolated T-shaped tri-level photovoltaic grid-connected inverter, so that the midpoint potential of the direct-current side of the tri-level inverter can be balanced, the amplitude and frequency of common-mode voltage change can be suppressed, accordingly, common-mode current of the non-isolated T-shaped tri-level photovoltaic grid-connected inverter is suppressed, and the efficiency, the size, the weight and the cost of a system are optimized.

Description

technical field [0001] The invention belongs to the technical field of solar photovoltaic power generation, and in particular relates to a common-mode voltage suppression method of a non-isolated T-type three-level photovoltaic grid-connected inverter. Background technique [0002] As an inexhaustible clean energy, solar energy has undoubtedly become one of the sustainable green energy sources. Photovoltaic grid-connected inverter is a device used to convert the direct current generated by solar energy into alternating current that meets the grid requirements through DC / AC and then connects to the grid. Its performance not only affects and determines whether the entire photovoltaic grid-connected system is reliable, safe and stable. , efficient operation, but also the main factor determining the life of the entire system. Efficiency and grid-connected current quality are two important indicators for measuring photovoltaic grid-connected inverters. [0003] The output volta...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/483
CPCH02J3/38H02M1/12H02M7/483H02M1/0048H02M1/123Y02B70/10
Inventor 孙向东来璐安少亮任碧莹
Owner XIAN UNIV OF TECH
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