A Novel Transformerless Inverter Topology Without Zero-Crossing Distortion

Tarak Salmi, Mounir Bouzguenda, Adel Gastli, Ahmed Masmoudi


The elimination of the transformer in solar photovoltaic inverters has reduced the size, the weight and the losses in the system.  On the other hand, the galvanic connection between the DC source and the grid generates leakage current through the earth parasitic capacitance. The leakage current depends on both the inverter topology and the control strategy. Among the existing inverters is the Highly Efficient and Reliable Inverter Concept (HERIC) topology that has low leakage current level and high efficiency. However, this topology suffers from low frequency harmonics and current zero crossings distortions. To eliminate these harmonics and distortions, a new transformerless inverter is proposed.   The design is a conventional full bridge inverter with an extra AC bypass.  The bypass branch disconnects the inverter from the grid during the freewheeling period.  Simulation results indicate that the zero crossings distortions are totally eliminated and that the low frequency harmonics are significantly reduced as a result of the appropriate applied control.  Moreover, losses analysis of the proposed design yields an efficiency of up to 94.14% and shows that the topology meets relevant standards.


PV, inverter, transformerless, common mode voltage, leakage current, ripples, harmonics, zero crossings distortions.

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Fritz Schimpf, Lars E. Norum, “Grid Connected Converters for Photovoltaic, State of the Art, Ideas for Improvement of Transformerless Inverters”, NORPIE/2008, Nordic Workshop on Power and Industrial Electronics, June 9-11, 2008, pp.1-5.

T. Kerekes, R. Teodorescu, M. Liserre, “Common Mode Voltage in case of Transformerless PV Inverters Connected to the Grid”, IEEE International Symposium on Industrial Electronics, June 30th- July 2nd 2008, pp. 2390 – 2395.

W.T. Franke, N. Oestreich, F.W. Fuchs, "Comparison of Transformerless Converter Topologies for Photovoltaic Application Concerning Efficiency and Mechanical Volume", IEEE International Symposium on Industrial Electronics, 2010, pp.724-729.

Oscar Lopez, Remus Teodorescu, Francisco Freijedo, Jesus Doval-Gandoy, "Eliminating Ground Current in a Transformerless Photovoltaic Application", IEEE Transactions on Energy Conversion, Vol. 25, No 1, Mar. 2010, pp. 140-147.

W. Bower and J. Wiles, “Investigation of Ground-Fault Protection Devices for Photovoltaic Power System Applications”, Proceedings of the 28th IEEE Conference on Photovoltaic Specialists, 2000, pp. 1378–1383.

Roberto González, Eugenio Gubía, Jesús López, and Luis Marroyo, “Transformerless Single-Phase Multilevel-Based Photovoltaic Inverter”, IEEE Transactions on Industrial Electronics, Vol. 55, No. 7, July 2008, pp.2694-2702.

Lin Ma, Fen Tang, Fei Zhou, Xinmin Jin and Yibin Tong, "Leakage Current Analysis of a Single-Phase Transformer-less PV inverter connected to the grid", Proceedings of the IEEE International Conference on Sustainable Energy Technologies, 24-27 Nov. 2008, pp.285-289.

Roberto Gonzalez, Jesus Lopez, Pablo Sanchis, Eugenio Gubia, Alfredo Ursua and Luis Marroy, “High-Efficiency Transformerless Single-phase Photovoltaic Inverter”, Proceedings of the 12th IEEE Conference on Power Electronics and Motion Control, 30 Sep. 2006, pp.1895-1900.

Valentini, M. Raducu, A. Sera, D. Teodorescu, R., “PV inverter test setup for European efficiency, static and dynamic MPPT efficiency evaluation”, Proceedings of11th International Conference on Optimization of Electrical and Electronic Equipment, OPTIM 2008,Printed on CD.

T. Kerekes, R. Teodorescu, and U. Borup, “Transformerless Photovoltaic Inverters Connected to the Grid”, Proceedings of the APEC 2007, Feb. 25 - March 01, pp. 1733–1737.

Rodríguez, Gerardo Vázquez, Emiliano Aldabas, “A new high-efficiency single-phase transformerless PV inverter topology”, IEEE Transactions on Industrial Electronics, June 2009, pp.1-5.

Huafeng Xiao, Shaojun Xie, “Leakage current analytical model and application in single-phase Transformerless photovoltaic grid-connected inverter”, IEEE Transaction on Electromagnetic Compatibility, Vol.52, No. 4, Nov 2010, pp.902-913.

“IEEE Recommended Practices and Requirements for Harmonic control in Electrical Power Systems”, IEEE Standard 519-1992.

Andrew Kotsopolos, Peter J.M. Heskes, Mark J.Jasen, “Zero-Crossing Distortion In Grid-Connected PV Inverters”, IEEE Transactions on Industrial Electronics, Vol. 52, No.2, April 2005, pp. 558-565.

J. Myrzik, M. Calais, "String and Module Integrated Inverters for Single Phase Grid Connected Photovoltaic Systems- A Review", Proceedings of the IEEE Conference on Power Tech, Bologna, Italy, 23-26 June 2003, Vol.2.

Samuel Vasconcelos, Araujo, Peter Zacharias, Regine Mallwitz, “High Efficient Single-Phase Transformerless Inverter for Grid-Connected Photovoltaic Systems”, IEEE Transactions on Industrial Electronics, Vol. 57, No. 9, Sep. 2010, pp. 3118-3128.

G. Buticchi, G. Franceschini, E. Lorenzani, "Compensation Strategy of Actual Commutations for PV Transformerless Grid-Connected Converters", Proceedings of the XIX International Conference on Electrical Machines, Rome 6-8 Sept.2010, pp. 1-5.

Sushant Kumar Pattnaik, K.K Mahapatra, “Power loss Estimation for PWM and Soft-switching Inverter using RDCLI”, On Proceeding of IMECS, Vol. 2, Mar 17th-19th 2010.

F. Casanellas, “Losses in PWM Inverters Using IGBTs”, Proceedings in IEEE Power Electronics Applications, Vol. 141, No. 5, Sept. 1994, pp. 235-239.

Alberto Guerra, Kohji Andoh, Silvestro Fimiani, “Ultra-Fast Recovery Diodes Meet Today’s Requirements For High Frequency Operation and Power Ratings in SMPS Applications”, International Rectifier, Jul. 14th 2000, pp. 1-9.

H.F Xiao, S.J. Xie, C. Yang, R.H. Huang, "An Optimized Transformerless Photovoltaic Grid-Connected Inverter", IEEE Transactions on Industrial Electronics, Vol.99, June 2010, pp. 1-9.

YUAN Liqiang, ZHAO Zhengming, YANG Zhi, “Power Losses for IGCTs and Diodes in MV Three-level Inverters”, Proceedings of the IEEE International Conference on Electronics and Drives Systems, Nov. 2005, pp. 205-208.

Tanel Jalakas, Dmitri Vinnikov, “Prediction of Semiconductor Losses in a High-Power High-Voltage DC/DC Converter”, Doctoral School of Energy-and Geo-Technology, Jan. 15th-20th 2007, Kuressaare, Estonia, pp. 114-117.


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