A Comparison of Half Bridge & Full Bridge Isolated DC-DC Converters for Electrolysis Application

ABSTRACT:

This paper presents a comparison of half bridge and full bridge isolated, soft-switched, DC-DC converters for Electrolysis application. An electrolyser is a part of renewable energy system which generates hydrogen from water electrolysis that used in fuel cells. A DC-DC converter is required to couple electrolyser to system DC bus. The proposed DC-DC converter is realized in both full-bridge and half-bridge topology in order to achieve zero voltage switching for the power switches and to regulate the output voltage. Switching losses are reduced by zero voltage switching. Switching stresses are reduced by using resonant inductor and capacitor. The proposed DC-DC converter has advantages like high power density, low EMI, reduced switching stresses, high circuit efficiency and stable output voltage. The MATLAB simulation results show that the output of converter is free from the ripples and regulated output voltage and this type of converter can be used for electrolyser application. Experimental results are obtained from a MOSFET based DC-DC Converter with LC filter. The simulation results are verified with the experimental results.

KEYWORDS:

  1. DC-DC converter
  2. Electrolyser
  3. Renewable energy sources
  4. Resonant converter
  5. TDR

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

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Fig 1. Half Bridge DC-DC Converter.

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Fig 2. Full Bridge DC-DC Converter.

 EXPECTED SIMULATION RESULTS:

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Fig 3 (b) Driving Pulses

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Fig 4 (c) Inverter output voltage with LC filter

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Fig 5 (d) Transformer secondary voltages

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Fig 6 (e) Output voltage and current

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Fig 7 (b) Driving Pulses

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Fig 8 (c) Inverter output voltage with LC filter

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Fig 9 (d) Transformer secondary voltage

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Fig 10 (e) Output voltage and current

 CONCLUSION:

 A comparison of half bridge and full bridge isolated DC-DC converters for Electrolysis application are presented. DC-DC converters for electrolyser system is simulated and tested with LC filter at the output. The electrical performances of the converter have been analyzed. The simulation and experimental results indicate that the output of the inverter is nearly sinusoidal. The output of rectifier is pure DC due to the presence of LC filter at the output. Switching losses are reduced by zero voltage switching. Switching stresses are reduced by using resonant inductor and capacitor The advantages of resonant converter are reduced (di/dt), low switching losses and high efficiency. Switching losses are reduced by zero voltage switching. Switching stresses are reduced by using resonant inductor and capacitor The converter maximizes the efficiency through the zero voltage switching and the use of super-junction MOSFET as switching devices with high dynamic characteristics and low direct voltage drop. Half bridge converter is found to be better than that of full bridge converter.

REFERENCES:

[1] E.J.Miller, “Resonant switching power conversion,”in Power Electronics Specialists Conf.Rec., 1976, pp. 206-211.

[2] V. Volperian and S. Cuk , “A complete DC analysis of the series resonant converter”, in IEEE power electronics specialists conf. Rec. 1982, pp. 85-100.

[3] R.L. Steigerwald, “High-Frequency Resonant Transistor DC-DC Converters”, IEEE Trans. On Industrial Electronics, vol.31, no.2, May1984, pp. 181-191.

[4] D.J. Shortt, W.T. Michael, R.L. Avert, and R.E. Palma, “A 600 W four stage phase-shifted parallel DC-DC converter,”, IEEE Power Electronics Specialists Conf., 1985, pp. 136-143.

[5] V. Nguyen, J. Dhayanchand, and P. Thollot, “A multiphase topology series-resonant DC-DC converter,” in Proceedings of Power Conversion International, 1985, pp. 45-53.