Review and Comparison of Step-Up Transformerless Topologies for Photovoltaic AC-Module Application

ABSTRACT:

This paper presents a inclusive review of step-up single phase non isolated inverters suitable for ac-module use. In order to measure the most feasible solutions of the reviewed topologies, a benchmark is set.

SEMICONDUCTOR

This benchmark is based on a typical ac-module application considering the want for the solar panels and the grid.The selected solutions are produce and simulated complying with the benchmark get passive and semiconductor components ratings in order to perform a comparison in terms of size and cost.

TOPOLOGIES

A discussion of the analyzed topologies concerning the get ratings as well as ground currents is given. Advice for topological solutions submit with the application benchmark are supply.

KEYWORDS:

  1. AC-module
  2. Photovoltaic(PV)
  3. Step-up Inverter
  4. Transformerless

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

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Fig.1 Block diagram of a two stage topology for an ac module

STEP-UP TRANSFORMERLESS INVERTERS:

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Fig 2 Boost converter and full bridge inverter

Time sharing boost converter with full bridge inverter

Fig 3 Time sharing boost converter with full bridge inverter

Parallel resonant soft switched boost converter and full bridge inverter

Fig 4 Parallel resonant soft switched boost converter and full bridge inverter

Parallel input series-output bipolar dc output converter and full bridge inverter

Fig 5 Parallel input series-output bipolar dc output converter and full bridge inverter

Boost converter and half bridge inverter

Fig 6 Boost converter and half bridge inverter

Boost converter and neutral point clamped inverter

Fig 7 Boost converter and neutral point clamped inverter

Series combined boost and buck boost and half bridge inverter

Fig 8 Series combined boost and buck boost and half bridge inverter

Center-tapped coupled inductor converter with bipolar output and half bridge inverter

Fig  9 Center-tapped coupled inductor converter with bipolar output and half bridge inverter

Single inductor bipolar output buck-boost converter and half bridge inverter

Fig 10 Single inductor bipolar output buck-boost converter and half bridge inverter

 Boost + FB integrated and dual grounded

Fig  11 Boost + FB integrated and dual grounded

Block diagram of a pseudo-dc-link topology for an ac module

Fig 12 Block diagram of a pseudo-dc-link topology for an ac module

Buck-boost DCM converter and unfolding stage

Fig 13 Buck-boost DCM converter and unfolding stage

Noninverting buck-boost DCM converter and unfolding stage

Fig 14 Noninverting buck-boost DCM converter and unfolding stage

Switched inductor buck boost DCM converter and unfolding stage

Fig 15 Switched inductor buck boost DCM converter and unfolding stage

 Boost buck time sharing converter and unfolding stage

Fig 16 Boost buck time sharing converter and unfolding stage

Block diagram of a single stage topology for an ac module

Fig 17 Block diagram of a single stage topology for an ac module

Universal single stage grid connected inverter

Fig 18 Universal single stage grid connected inverter

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Fig 19 Integrated boost converter

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Fig 20 Differential boost converter

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Fig 21 Boost inverter with improved zero crossing.

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Fig 22 Integrated Buck boost inverter

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Fig 23 Buck Boost inverter with extended input voltage range

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Fig 24 Differential buck boost inverter

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Fig 25 Two sourced anti parallel buck boost inverter

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Fig 26 Single stage full bridge buck boost inverter

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Fig 27 Buck boost based single stage inverter

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Fig 28 Switched inductor buck boost based single stage inverter

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Fig 29 Single inductor buck boost based inverter

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Fig 30 Doubly grounded single inductor buck boost based inverter

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Fig 31 Single inductor  buck boost based inverter with dual ground

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Fig 32 Three switch buck boost inverter

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Fig 33 Coupled inductor buck boost inverter

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Fig 34 Impedance-admittance conversion theory based inverter

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Fig 35 Single phase Z source inverter

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Fig 36 Semi quasi Z source inverter with continuous voltage gain

 

CONCLUSION:

In this paper, a inclusive review of single phase non isolated inverters for ac module use is given. Both the grid relation and the solar panel want are analyzed stress the leakage current regulation as it is a main disturb in non isolated PV grid connected inverters.

SEMICONDUCTOR

In order to compare the most suitable solutions of the reviewed topologies under the same requirement, a benchmark of a typical ac module use is set.These solutions have been designed and simulated, get ratings for the passive and the semiconductor components. These ratings are used for the topology comparison in terms of size and cost.

TRANSFORMERLESS

Furthermore, detailed simulations of typical topologies have been achieve using semiconductor and inductor models to estimate the efficiency of the reviewed solutions. As a result of the comparison, the required voltage boost necessary for the connection to the European grid is difficult to achieve with transformerless topologies, but it is able for U.S. want.

DC-DC

Two stage topologies, including the solution with dual grounding efficiency that in theory avoids the ground leakage currents, are the chosen option for the set benchmark in which switching density for the dc-dc stage is set twice than for the dc-ac one.

INVERTER

The two stage combination of a step-up dc-dc converter and a step-up inverter should be thought-out In addition, the consider pseudo-dc-link reach  are an alternative solution in terms of size and cost.

DCM

Moreover, ground currents are normal to be low in these solutions because of the line density interface and weighted ability is the highest due to the flat behavior of the ability with the output power. The consider single stage topologies have higher cost than the other consider solutions and control is normal to be more complex to avoid dc current injection.

RMS

In addition, DCM operation mode allows smaller solutions, including a solution with dual ground efficiency, but ability is lower due to the high RMS currents.

 

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