Photovoltaic high-frequency chain grid-connected inverter capable of restraining input low-frequency current ripples

A ripple suppression and low-frequency current technology, which is applied in the field of photovoltaic high-frequency chain grid-connected inverters, can solve problems such as digital implementation difficulties and controller design, and achieve the effects of easy digital control, simplicity, and low-frequency current ripple suppression

Inactive Publication Date: 2015-04-01
YANCHENG INST OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Usually, the two-stage circuit suppresses LFCR on the input side by using a high-performance controller, but

Method used

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  • Photovoltaic high-frequency chain grid-connected inverter capable of restraining input low-frequency current ripples
  • Photovoltaic high-frequency chain grid-connected inverter capable of restraining input low-frequency current ripples
  • Photovoltaic high-frequency chain grid-connected inverter capable of restraining input low-frequency current ripples

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Example Embodiment

[0093] Design example: 4 photovoltaic cells are connected in series, the maximum power point voltage and current of a single cell are 36V and 5.56A respectively. It is stipulated that the low-frequency ripple of the converter input current is not allowed to exceed 5% of its average current; grid parameters: 110VAC / 50Hz. The design steps are as follows:

[0094] ①Determine the working frequency of the circuit resonant DC / DC converter at 50kHz. In order to reduce the switching loss, the switching frequency of the fixed power frequency inverter is 10kHz;

[0095] ②According to the grid voltage and considering the volatility of the output voltage of the resonant DC / DC converter, determine that the output voltage of the DC / DC converter is equal to 200V;

[0096] ③According to the photovoltaic cell parameters, the maximum power point voltage is 144V; according to formula (24), the transformation ratio of the transformer should be less than 0.26, and n=0.25;

[0097] ④According to the maximu...

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Abstract

The invention discloses a photovoltaic high-frequency chain grid-connected inverter capable of restraining input low-frequency current ripples. The inverter comprises a first inverter, an LCL-T resonance network, a high-frequency transformer, a rectifier circuit, a direct-current filter circuit, a second inverter and an LCL filter. The input end of the first inverter is connected with a photovoltaic array, and the output end of the first inverter is connected with the LCL-T resonance network. The LCL-T resonance network comprises a T circuit which is composed of an inductor Lr, a capacitor Cr and an inductor Lk. The inductor Lr is connected to the output end of the first inverter in series, and the inductor Lk is connected with the primary side of the high-frequency transformer in series and then connected with the capacitor Cr in parallel. The secondary side of the high-frequency transformer is connected with the rectifier circuit, the direct-current filter circuit and the second inverter in sequence. The LCL filter is connected to the output end of the second inverter, and the output end the LCL filter is electrically connected with a grid. By applying the LCL-T resonance network to the photovoltaic high-frequency chain grid-connected inverter, the low-frequency current ripples in output current of a photovoltaic module can be effectively restrained.

Description

technical field [0001] The invention relates to a photovoltaic high-frequency chain grid-connected inverter with the function of suppressing input low-frequency current ripple. Background technique [0002] With the continuous decline in the price of photovoltaic modules and the promulgation of relevant national policies and regulations, photovoltaic power generation will surely become an important part of the utilization of renewable energy. In the photovoltaic system, the power converter plays a very important role, including the maximum power point tracking (MPPT) of the photovoltaic cell, and the form of electric energy required by the high-quality output load. The decline in the price of photovoltaic cells has led to an increasing proportion of the cost of power converters in photovoltaic power generation systems; in addition, the efficiency of converters directly determines the utilization of photovoltaic modules. Therefore, low cost and high efficiency are the goals ...

Claims

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Application Information

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IPC IPC(8): H02M7/537H02M1/12
CPCY02E10/56H02M7/537H02M1/12H02M1/126
Inventor 吴冬春吴云亚阚加荣陆广平顾春雷胡国文
Owner YANCHENG INST OF TECH
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