A RESONANT CONVERTER FOR PHOTOVOLTAIC SYSTEMS

ALL PHOTOVOLTAIC (PV) SYSTEMS REQUIRE POWER ELECTRONICS TO CONVERT VARIABLE VOLTAGE DC FROM THE PV PANELS TO USABLE, REGULATED POWER WITH HIGH QUALITY. AT HIGH RATINGS, AC IS GENERALLY REQUIRED. CONVENTIONAL CONVERTERS HAVE SEVERAL PROBLEMS, INCLUDING HIGH COST, EXCESSIVE HARMONICS, EXCESSIVE LOSSES, SAFETY ISSUES, POOR POWER FACTOR, VULNERABILITY OF THE POWER SWITCHES, AUDIBLE NOISE, AND ELECTROMAGNETIC INTERFERENCE (EMI) IN VIOLATION OF FCC STANDARDS. AN INNOVATIVE RESONANT CONVERTER KNOWN AS THE UNIPOLAR SERIES RESONANT CONVERTER (USRC) WILL MAKE SIGNIFICANT IMPROVEMENT IN EACH AREA. THE USRC USES THYRISTORS WITH ZERO VOLTAGE AND CURRENT SWITCHING, MINIMIZING LOSSES AND COST. IT PRODUCES SINUSOIDAL VOLTAGE WITHIN 1EEE 519 STANDARDS, ELIMINATING FILTERS AND ASSOCIATED ENERGY LOSSES AND COST. THE USRC CAN STEP UP VOLTAGE WITHOUT A TRANSFORMER. VERSIONS OF THE USRC ARE OPERATING, BUT ADAPTATION TO PV APPLICATIONS IS REQUIRED. THIS PROCJECT WILL DEVELOP A FOUR-WIRE VERSION WITH A GROUNDED NEUTRAL LEG THAT PERMITS THE GROUNDING OF BOTH THE PB SYSTEM AND LOAD WITHOUT ISOLATION TRANSFORMERS. IN PHASE I, A 3 KW VERSION WILL BE ASSEMBLED AND TESTED IN THE LABORATORY. IN ADDITION, THE COST AND PERFORMANCE OF A 100 KW MODULE WILL BE PROJECTED. IN PHASE II, THE 100 KW MODULE COULD BE DEMONSTRATED IN THE FIELD. THE 100 KW MODULE COULD BE INSTALLED IN PARALLEL WITH OTHER SIMILAR MODULES IN BOTH GRID-CONNECTED AND STANDALONE PV SYSTEMS. THE WIDE CONVERSION FUNCTIONALITY OF THE USRC TECHNOLOGY MAKES IT A LIKELY CANDIDATE FOR HYBRID ENERGY SYSTEMS. A COST OF LESS THAN $100/KW IS ATTAINABLE FOR THE SYSTEM.