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A digital control method for a two-stage three-phase three-level photovoltaic grid-connected inverter

A three-level inverter, digital control technology, applied in photovoltaic power generation, electrical components, circuit devices, etc., can solve the problems of bus voltage drop, reduce bus capacitance, overshoot, etc., achieve rapid dynamic response, reduce Input impedance, the effect of enhanced disturbance rejection capability

Inactive Publication Date: 2016-10-26
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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Problems solved by technology

[0005] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a digital control method for a two-stage three-phase three-level photovoltaic grid-connected inverter that reduces the bus capacitance, by reducing the input impedance of the inverter , to solve the bus voltage drop and overshoot caused by the sudden increase or decrease of photovoltaic cell power, thereby reducing the bus capacitance

Method used

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  • A digital control method for a two-stage three-phase three-level photovoltaic grid-connected inverter
  • A digital control method for a two-stage three-phase three-level photovoltaic grid-connected inverter
  • A digital control method for a two-stage three-phase three-level photovoltaic grid-connected inverter

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Embodiment approach

[0033] Such as figure 1 As shown in (b), in the two-stage photovoltaic grid-connected inverter, the front stage is a BOOST converter, and the rear stage uses a mid-point clamped three-level inverter, and the bus capacitance is 200μF; TMS320F2812DSP is used as the digital control device. Control methods such as figure 2 As shown, the implementation method of its specific control strategy is as follows:

[0034]The AD converter of the DSP samples the three-phase inductor current, the three-phase grid voltage, the inductor current of the BOOST converter, and the bus voltage, and multiplies the proportional coefficient inside the DSP to obtain the actual value corresponding to each sampled value. The phase angle of the three-phase grid voltage is obtained through the phase-locked loop, and the current value in the ABC coordinate system is converted into the current vector in the synchronous d-q coordinate system according to the Park transformation and the Clark transformation....

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Abstract

The invention discloses a digital control method of a two-stage three-phase three-level photovoltaic grid-connected inverter. According to the method, a bus voltage outer ring, a d-axis capacitance current inner ring and a q-axis grid current inner ring are combined to control a three-level inverter. To solve the problem that a bus voltage control dynamic condition is slow in an exiting control mode, inverter grid-connected current and a modulation ratio are used for calculating equivalent bus capacitance current, a bus capacitance current loop is used for controlling SVPWM reference vectors of the inverter, input impedance of the inverter is reduced, inhibiting ability of bus voltage on disturbance caused by changes of power of photovoltaic cells is improved, and the capacitance value of a bus capacitor is lowered. By means of the method, a thin-film capacitor with small capacitance value and high reliability can be adopted in the inverter, and reliability of the inverter is improved.

Description

technical field [0001] The invention relates to a digital control method of a two-stage three-phase three-level photovoltaic grid-connected inverter that reduces bus capacitance, and belongs to the control technology of photovoltaic inverters. Background technique [0002] With the depletion of fossil energy, photovoltaic power generation, as a new energy source, has become a promising one due to its direct generation of electric energy, no mechanical rotating parts, no noise pollution, easy installation, easy transfer, and long service life. Power generation technology with developmental significance. [0003] The non-isolated grid-connected inverter has simple structure, low cost, and high efficiency because it does not require heavy power frequency transformers or high-frequency transformers for loads. Compared with the single-stage structure, the front stage of the two-stage grid-connected inverter is a boost converter, which can reduce the number of photovoltaic cells ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/487H02M7/5387
CPCH02J3/383H02M7/487Y02E10/56
Inventor 金科沈志远张艺文
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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