Z-source-converter-based energy-recycling zero-voltage electronic loads

This paper proposes two high-efficiency energyrecycling zero-voltage electronic loads (ELs) based on a Z-source converter. ELs are a family of power converters which are used as variable impedance loads in several applications. Such applications include testing of photovoltaic (PV) cells, power converters, and power supplies or frequency control of stand-alone microgeneration. In PV-cell performance tests, the zero-voltage operation, near the short-circuit point of the PV cell's I-V curve, creates a challenge for EL design. The converter that is suitable for this application must have the ideal current source behavior because the challenge is to draw a specific constant current from the source under test even during the zero-voltage condition. The energy recycling principle increases the efficiency and allows the construction of high-power ELs. The proposed topologies are based on the Z-source converter and achieve the ideal current source behavior of draining an adjustable current even when the source voltage is zero. These topologies also provide power recycling for energy saving and for developing high-power ELs. The first configuration is based on the traditional Z-source converter, and the second one is based on the recently proposed quasi Z-source converter. Two prototypes were analyzed and built. Experimental results are provided to verify the principle of operation.