Full Soft-Switching High Step-Up Current-Fed DC-DC Converters with Reduced Conduction Losses



Two variants of the full soft-switching high step-up DC-DC converter are prepared. The main advantage of the converters is the minimized conduction losses by the use of the four-quadrant switches and a specific control algorithm. Simulation was achieve to verify the principle of operation and to decide the losses.


  1. DC-DC power converters
  2. Photovoltaic systems
  3. Soft switching
  4. Step-up
  5. Isolated




Fig. 1. Full soft-switching high step-up DC-DC converter

Fig. 2. Proposed converter topology with four four-quadrant switches.


 Fig. 3. Simulated voltage and current waveforms of S1 (a), S2 (b), S7.1 (c), S5 (d) for the proposed converter topology with a single four-quadrant switch


The planned converters allow soft-switching of the both inverter and rectifier change without any auxiliary passive elements and clamping circuits.As seen from simulation results, the topology with a single four-quadrant switch has higher ability than the topology with four four-quadrant switches


but at the same time, it has few disadvantages that could affect the final choice of topology:- Step-up factor is alittle lower than in the topology with four four-quadrant switches;- The switching interval e (and the symmetrical interval in another half-period) must be of closely right duration, which is equal to the time of current redistribution between switches S4 and S2.


The shorter duration of this interval will result in high switching losses and, in very great cases, can lead to damage of the switch S4. The easily longer duration will result in current increase through the switch S2 and finally may result in the boost inductor saturation.


– The original topology and the topology with four four quadrant switches does not have the problem with the longer duration of this switching interval and so they have lower want to the control system in dynamic mode. This means that planned converter with four four-quadrant switches allows robust soft-switching commutation


which is hard to achieve in galvanically isolated current-fed DC-DC converters.The main disadvantage of the geography is the presence of four switches in series in the inverter stage on the path of the current flow during the energy transfer interval.


This leads to the conduction losses higher than in the conventional phase shifted full-bridge topology. Nevertheless the switching losses are lower due to the introduced soft-switching. It means that switching density could be


increased while maintaining the efficiency at acceptable level.Future work will be dear to the experimental verification of the planned converters and further control algorithm increase.


[1] A. Blinov, D. Vinnikov, and V. Ivakhno, “Full soft-switching high stepup dc-dc converter for photovoltaic applications,” 2014 16th European Conference on Power Electronics and Applications (EPE’14-ECCE Europe), pp. 1–7, Aug 2014.

[2] Y. Sokol, Y. Goncharov, V. Ivakhno, V. Zamaruiev, B. Styslo, M. Mezheritskij, A. Blinov, and D. Vinnikov, “Using the separated commutation in two-stage dc/dc converter in order to reduce of the power semiconductor switches’ dynamic losses,” Energy Saving. Power Engineering. Energy Audit, 2014.

[3] A. Blinov, V. Ivakhno, V. Zamaruev, D. Vinnikov, and O. Husev, “Experimental verification of dc/dc converter with full-bridge active rectifier,” 38th Annual Conference on IEEE Industrial Electronics Society (IECON 2012), pp. 5179–5184 , Oct 2012.

[4] R.-Y. Chen, T.-J. Liang, J.-F. Chen, R.-L. Lin, and K.-C. Tseng, “Study and implementation of a current-fed full-bridge boost dc-dc converter with zero-current switching for high-voltage applications,” IEEE Transactions on Industry Applications, vol. 44, no. 4, pp. 1218–1226, July 2008.

[5] J.-F. Chen, R.-Y. Chen, and T.-J. Liang, “Study and implementation of a single-stage current-fed boost pfc converter with zcs for high voltage applications,” IEEE Transactions on Power Electronics, vol. 23, no. 1, pp. 379–386, Jan 2008.

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