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Photovoltaic grid-connected inverter of Boost and Buck cascade and control method thereof

An inverter and photovoltaic technology, which is used in photovoltaic power generation, irreversible DC power input conversion to AC power output, single-grid parallel feeding arrangement, etc., can solve the complex control logic and compensation of the front-stage DC/DC converter. circuit and other problems, to achieve the effect of smooth switching and high conversion efficiency

Inactive Publication Date: 2009-12-23
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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  • Application Information

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Problems solved by technology

This makes the switching process of the previous DC / DC converter require complex control logic and compensation circuits to complete

Method used

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  • Photovoltaic grid-connected inverter of Boost and Buck cascade and control method thereof
  • Photovoltaic grid-connected inverter of Boost and Buck cascade and control method thereof
  • Photovoltaic grid-connected inverter of Boost and Buck cascade and control method thereof

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specific example

[0034] A specific example of the present invention is as follows: battery panel voltage U pv =200~550V, grid voltage U grid =220VRMS, grid frequency f grid =50Hz, rated power P N = 3kW; inductance L 1 =0.2mH,L 2 =8mH; intermediate capacitance C=5μF; switching frequency f=50kHZ. attached Figure 5 , 6 It is the specific simulation waveform diagram of this example, in which, the attached Figure 5 It is the grid current waveform diagram when the present invention works at full load under different input voltages; Figure 6 It is the grid current waveform diagram when the present invention works under light load under different input voltages.

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Abstract

The invention discloses a photovoltaic grid-connected inverter of Boost and Buck cascade and a control method thereof; the inverter comprises a main circuit composed of four branch circuits and a switch control circuit composed of four branch circuits. The pre-stage DC / DC converter in the method works in an SPWM way and provides sine half-wave current for the post stage, the post-stage DC / AC converter switches at power frequency, and the conversion efficiency of the whole machine is high; a control strategy adopts a uniform compensation circuit at a Boost-Buck mode; and the duty cycle of a Boost switch tube is formed by subtracting a fixed amount on the basis of the duty cycle of a Buck switch tube. In the converter, only one switch tube works at high frequency at any time and the efficiency of the converter is high; the work mode of the pre-stage DC / DC converter achieves smooth switch; and the converter needs no electrolytic capacitor and has long life.

Description

technical field [0001] The present invention relates to a Boost and Buck cascaded photovoltaic grid-connected inverter and a control method thereof, which belong to a grid-connected inverter and a control method of grid-connected current. Background technique [0002] Grid-connected inverters used in new energy generation such as photovoltaics and wind power have a relatively large input side voltage variation range. In order to achieve grid connection, the grid-connected inverter needs to implement a buck-boost function to cope with a wide range of voltage changes. The traditional two-stage grid-connected inverter is generally composed of a front-stage DC / DC converter and a rear-stage DC / AC inverter. The front-stage DC / DC converter generally uses a Boost converter to boost the input voltage. When the input voltage When it is higher, the Boost converter stops working, and the DC / AC converter of the subsequent stage realizes step-down, which is not conducive to the optimal de...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/48H02M7/537H02J3/38
CPCY02E10/563Y02E10/56
Inventor 谢少军许津铭肖华锋
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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