Grid-connected photovoltaic inverter device and control method for improving conversion efficiency thereof

An inverter, photovoltaic technology, applied in the direction of irreversible DC power input conversion to AC power output, AC power input conversion to DC power output, photovoltaic power generation, etc., to achieve reasonable power distribution, easy expansion and maintenance, The effect of improving overall efficiency

Inactive Publication Date: 2011-02-23
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, this method only optimizes the efficiency of the system at light load, ignoring the fact that the DC / AC converter generally has the highest conversion efficiency when it operates at 50% to 60% load.

Method used

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  • Grid-connected photovoltaic inverter device and control method for improving conversion efficiency thereof
  • Grid-connected photovoltaic inverter device and control method for improving conversion efficiency thereof
  • Grid-connected photovoltaic inverter device and control method for improving conversion efficiency thereof

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Embodiment Construction

[0036] The principle diagram of a control method for improving the conversion efficiency of the grid-connected inverter device involved in the present invention is as follows figure 1 As shown, it includes a power generation unit, a DC bus 1, a DC-AC conversion circuit 2, a voltage outer loop control circuit 3, and a current inner loop control and modulation circuit 4; wherein the power generation unit includes a photovoltaic array connected in sequence, a DC-DC conversion device; the current inner loop control and modulation circuit 4 includes a current inner loop control circuit and a PWM generation circuit connected in sequence; wherein, the output end of the power generation unit is connected to the input end of the DC bus, and the output end of the DC bus 1 is connected to the DC in turn. - The AC conversion circuit 2 is connected to the AC power grid, and the voltage outer loop control circuit 3 is respectively connected to the DC bus 1 and the current inner loop control ...

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Abstract

The invention discloses a grid-connected photovoltaic inverter device and a control method for improving conversion efficiency thereof and belongs to the field of inverter control. The device comprises N grid-connected photovoltaic inverters, wherein a voltage outer loop control circuit (3) of each grid-connected photovoltaic inverter comprises a bus voltage sampling circuit (301), first and second bus voltage regulators (302 and 303), first and second amplitude limiting circuits (304 and 305) and three voltage loops. The control method comprises that: given voltage in different grades is respectively set for the bus voltage regulators of the plurality of grid-connected inverters; along with the increase of the input power, the inverters work in turn according to the given voltage, and the light load efficiency is improved by reducing the number of the operating inverters under the condition of light load; and different set values and output amplitude limiting values are applied to a linear bus voltage regulator of a single grid-connected inverter so as to ensure that the inverters can operate at the highest efficiency preferentially under different power grades, and the overall efficiency of the system is improved.

Description

technical field [0001] The invention relates to an inverter control method, in particular to a photovoltaic grid-connected inverter device and a control method for improving its conversion efficiency, belonging to the field of inverter control. Background technique [0002] With the shortage of traditional fuel energy, renewable energy sources such as solar energy and wind energy have gradually received extensive attention and research because of their environmental protection and many advantages such as no energy consumption. [0003] At present, in the grid-connected system of string photovoltaic power generation, the distributed parallel connection is mainly realized at the DC / DC converter, that is, a photovoltaic array is connected to a DC / DC converter respectively to realize maximum power tracking and avoid centralized photovoltaic arrays. The resulting interaction improves the efficiency of MPPT. After the output of the DC / DC converter is connected in parallel, a larg...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/48H02M7/5387H02J3/38
CPCY02E10/563Y02E10/56
Inventor 张犁胡海兵冯兰兰邢岩
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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