Simple Technique Reducing Leakage Current for H-Bridge Converter in Transformerless Photovoltaic Generation

Kot, Radoslaw;Stynski, Sebastian;Stepien, Krzysztof;Zaleski, Jaroslaw;Malinowski, Mariusz

  • 투고 : 2015.05.04
  • 심사 : 2015.06.30
  • 발행 : 2016.01.20


Given their structural arrangement, photovoltaic (PV) modules exhibit parasitic capacitance, which creates a path for high-frequency current during zero-state switching of the converter in transformerless systems. This current has to be limited to ensure safety and electromagnetic compatibility. Many solutions that can minimize or completely avoid this phenomenon, are available. However, most of these solutions are patented because they rely on specific and often complex converter topologies. This study aims to solve this problem by introducing a solution based on a classic converter topology with an appropriate modulation technique and passive filtering. A 5.5 kW single-phase residential PV system that consists of DC-DC boost stage and DC-AC H-bridge converter is considered. Control schemes for both converter stages are presented. An overview of existing modulation techniques for H-bridge converter is provided, and a modification of hybrid modulation is proposed. A system prototype is built for the experimental verification. As shown in the study, with simple filtering and proper selection of switching states, achieving low leakage current level is possible while maintaining high converter efficiency and required energy quality.


Leakage currents;Pulse width modulation (PWM);Renewable energy


  1. O. Lopez, R. Teodorescu, F. Freijedo, and J. D. Gandoy, "Leakage current evaluation of a single phase transformerless PV inverter connected to the grid," Applied Power Electronics Conference, APEC 2007-Twenty Second Annual IEEE, pp. 907-912, 2007.
  2. T. K. S. Freddy, N. A. Rahim, W.-P. Hew, and H. S. Che, “Comparison and analysis of single-phase transformerless grid-connected PV inverters,” IEEE Trans. Power Electron., Vol. 29, No. 10, pp. 5358-5369, Oct. 2014
  3. D. Meneses, F. Blaabjerg, O. García, and J. A. Cobos, “Review and comparison of step-up transformerless topologies for photovoltaic AC-module application,” IEEE Trans. Power Electron., Vol. 28, No. 6, pp. 2649-2663, Jun. 2013.
  4. R. Teodorescu, M. Liserre, and P. Rodrguez, Grid Converters for Photovoltaic and Wind Power Systems, Wiley-IEEE Press, 2011.
  5. T. Kerekes., "Analysis and modeling of transformerless photovoltaic inverter systems," PhD Thesis, Aalborg University, Aalborg, Denmark, 2009.
  6. X. Huafeng, S. Xie, Y. Chen, and R. Huang, “An optimized transformerless photovoltaic grid-connected inverter,” IEEE Trans. Ind. Electron., Vol. 58, No. 5, pp. 1887-1895, May 2011.
  7. G. Buticchi, D. Barater, E. Lorenzani, and G. Franceschini, “Digital control of actual grid-connected converters for ground leakage current reduction in PV transformerless systems,” IEEE Trans. Ind. Informat., Vol. 8, No. 3, pp. 563-572, Aug. 2012.
  8. T. Esram and P. L. Chapman, “Comparison of photovoltaic array maximum power point tracking techniques,” IEEE Trans. Energy Convers., Vol. 22, No. 2, pp. 439-449, Jun. 2007.
  9. Y. Yongheng, F. Blaabjerg, and H. Wang, “Low-voltage ride-through of single-phase transformerless photovoltaic inverters,” IEEE Trans. Ind. Appl., Vol. 50, No. 3, pp. 1942-1952, May/Jun. 2014.
  10. T. Friedli, M. Hartmann, and J. W. Kolar, “The essence of three-phase PFC rectifier systems — Part II,” IEEE Trans. Power Electron., Vol. 29, No. 2, pp. 543-560, Feb. 2014.
  11. D. Dong; L. Fang D. Boroyevich, and P. Mattavelli, “Leakage current reduction in a single-phase bidirectional AC–DC full-bridge inverter,” IEEE Trans. Power Electron.., Vol. 27, No. 10, pp. 4281-4291, Oct. 2012.
  12. M. A. G de Brito, L. Galotto, L. P. Sampaio, G. de Azevedo e Melo, and C. A. Canesin, “Evaluation of the main MPPT techniques for photovoltaic applications,” IEEE Trans. Ind. Electron., Vol. 60, No. 3, pp. 1156-1167, Mar. 2013.
  13. D. Sera, L. Mathe, and T. Kerekes, S.V Spataru, and R. Teodorescu, “On the perturb-and-observe and incremental conductance MPPT methods for PV systems,” IEEE J. Photovolt., Vol. 3, No. 3, pp. 1070-1078, Jul. 2013.
  14. A. K. Abdelsalam, A. M. Massoud, S. Ahmed, and P. Enjeti, “High-performance adaptive perturb and observe MPPT technique for photovoltaic-based microgrids,” IEEE Trans. Power Electron., Vol. 26, No. 4, pp. 1010-1021, April 2011
  15. F. Scarpetta, M. Liserre, and R.A Mastromauro, “Adaptive distributed MPPT algorithm for photovoltaic systems,” IECON 2012 - 38th Annual Conference on IEEE Industrial Electronics Society, pp. 5708-5713, 2012.
  16. R. Teodorescu, F. Blaabjerg, M. Liserre, and P.C Loh, “Proportional-resonant controllers and filters for grid-connected voltage-source converters,” IEE Proc. Electric Power Applications, Vol. 153, No. 5, pp. 750-762, 2006.
  17. L. Hadjidemetriou, E. Kyriakides, and F. Blaabjerg, “A new hybrid PLL for interconnecting renewable energy systems to the grid,”IEEE Trans. Ind. Appl., Vol. 49, No. 6, pp. 2709-2719, Nov./Dec. 2013.
  18. F. Blaabjerg, R. Teodorescu, M. Liserre, and A.V. Timbus, “Overview of control and grid synchronization for distributed power generation systems,” IEEE Trans. Ind. Electron., Vol. 53, No. 5, pp. 1398-1409, Oct. 2006
  19. S. Stynski, "Analisys and control of muitilevel AC-DC-AC flying capacitor converter fed trom single-phase grid," PhD Thesis, Warsaw University of Technology, Warsaw, Poland, 2012.