In this paper a full soft-switching high step-up DC-DC converter is brought in as an other approach to module integrated converters for photovoltaic use. The given operation principle and key equations can be used as design guidelines for component and parameter decision in practical use.
The prepared DC-DC converter was verified by help of simulations and test. Power loss analysis based on the semiconductor datasheet values showed that the converter tends to produce an ability of 92. 8% at the maximum power point.
- DC-DC power conversion
- Photovoltaic power systems
- MOSFET switches
Fig. 1: Generalised topology of the proposed DC-DC converter.
EXPECTED SIMULATION RESULTS:
Fig. 2: Simulated voltage and current waveforms of MOSFET SI (a), MOSFET Tl (b), transformer primary (c) as well as the input and output voltage and current waveforms (d).
Fig. 3: Converter regulation characteristics at different irradiation levels (a) and cell temperatures (b).
Fig. 4: Experimental voltage and current waveforms of Tl MOSFET (a), SI MOSFET (b) and S2 MOSFET (c).
Fig. 5: Experimental waveforms of the input (a) and output (b) voltage and current.
The planned high step-up DC-DC converter allows ZVS of the inverter switches and ZCS of the rectifier switches. The operation principle given and the mathematical analysis of the converter can be used as design direction for component and parameter decision in practical use.
The operation of the converter was verified with the 300 W experimental prototype and the experimental waveforms were found to agree to the evaluation ones. The major limitation of the converter lies in the diodes connected in series to the inverter transistors.
The static losses in these diodes will provide a major portion of the total converter losses.In the future these diodes will be replaced by MOSFETs, external snubber capacitors for rectifier switches will be introduced and the implementation potential of wide-bandgap semiconductors will be also addressed.
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