Design and Analysis of Highly Efficient and Reliable Single-Phase Transformerless Inverter for PV Systems

Authors: L. Ashok Kumar, N. Sujith Kumar

Abstract:

Most of the PV systems are designed with transformer for safety purpose with galvanic isolation. However, the transformer is big, heavy and expensive. Also, it reduces the overall frequency of the conversion stage. Generally PV inverter with transformer is having efficiency around 92%–94% only. To overcome these problems, transformerless PV system is introduced. It is smaller, lighter, cheaper and higher in efficiency. However, dangerous leakage current will flow between PV array and the grid due to the stray capacitance. There are different types of configurations available for transformerless inverters like H5, H6, HERIC, oH5, and Dual paralleled buck inverter. But each configuration is suffering from its own disadvantages like high conduction losses, shoot-through issues of switches, dead-time requirements at zero crossing instants of grid voltage to avoid grid shoot-through faults and MOSFET reverse recovery issues. The main objective of the proposed transformerless inverter is to address two key issues: One key issue for a transformerless inverter is that it is necessary to achieve high efficiency compared to other existing inverter topologies. Another key issue is that the inverter configuration should not have any shoot-through issues for higher reliability.

Keywords: Leakage current, common mode (CM), photovoltaic (PV) systems, pulse width modulation (PWM).

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1094633

References:

[1] M. Calais, J. Myrzik, T. Spooner, V. G. AgeJidis, "Inverters for single phase grid-connected photovoltaic system-an overview," Power Electronics Specialists Conference, Vol. 4, pp. 1995-2000, June 2002.
[2] M. Calais and V. Agelidis, "Multilevel converters for single phase grid-connected photovoltaic systems, an overview” in IEEE International Symposium on Industrial Electronics, 7-10, pp. 224-229, Jul. 1998.
[3] N. Jenkins "Photovoltaic systems for small scale remote power supplies” Power Engineering Journal, vol. 9, no. 2, pp. 89-96, Apr. 1995.
[4] M. Svrzek and G. Sterzinger, "Solar PV Development: Location of Economic Activity” Renewable Energy Policy Report 2005.
[5] M.J. de Wild-Scholten, E.A. Alsema, E.W. ter Horst, M. Bächler, and V.M. Fthenakis, "A Cost and Environmental Impact Comparison Of Grid-connected Rooftop and Ground Based PV Systems” in 21th European PV Solar Energy Conference, 4-8, pp.1-7, Sep. 2006.
[6] S. Kjær, J. Pedersen, and F. Blaabjerg, "A review of single phase grid-connected inverters for photovoltaic modules” IEEE Transactions on Industry Applications, vol. 41, no. 5, pp. 1292- 1306, Sep. 2005.
[7] H. Häberlin "Evolution of inverters for grid-connected PV systems from 1989 to 2000” in 17th European Photovoltaic Solar Energy Conference, 22-26, Oct. 2002.
[8] M Meinhardt and G. Cramer, "Past, Present and Future of grid-connected Photovoltaic and Hybrid Power Systems" in IEEE Power Engineering Society Summer Meeting,, pp. 1283-1288, Jul. 2000.
[9] M. Calais, J. Myrzik, T. Spooner, and V.G. Agelidis, "Inverters for single phase grid-connected photovoltaic systems an overview" in IEEE 33rd Annual Power Electronics Conference, pp. 1995 – 2000, Jun 2002.
[10] M. Abella and F. Chenlo, "Choosing the right inverter for grid-connected PV systems” Renewable Energy World, vol. 7, no. 2, pp. 132-147, Mar-Apr. 2004.
[11] J.M. Carrasco et al. "Power Electronic Systems for the Grid Integration of Renewable Energy Sources: A Survey” IEEE Transactions on Industrial Electronics, vol. 53, no. 4, pp. 1002-1016, Aug. 2006.
[12] Bo Yang, WuhuaLi,YunjieGu, Wenfeng Cui, and Xiangning He, Improved Transformerless Inverter With Common-Mode Leakage Current Elimination for a Photovoltaic Grid-connected Power System, IEEE transactions on power electronics, vol.27, February 2012.
[13] Rekioua D., Matagne E. Optimization of photovoltaic power systems: Modelization, Simulation and Control (2012) Green Energy and Technology, 102.