Simple and efficient low power photovoltaic emulator for evaluation of power conditioning systems

Low power conditioning systems are required for photovoltaic (PV) applications in portable devices, small satellites, solar vehicles, etc. The research and development of the power conditioning unit for this application such as MPPT requires of controllable environment conditions, which are difficult to obtain due to weather variability. Thus, a photovoltaic emulator is developed to obtain a power source that presents the same current-voltage (I-V) relationship of PV cells according to the connected-load, irradiance and temperature. This paper presents the design of a PV system based on a synchronous buck converter, current and voltage sensors, and a microcontroller to control the PWM duty cycle to adjust the output voltage and current according to the I-V characteristic. The results show a good agreement between the output current of the emulator and the expected characteristic curve of the PV module; the achieved efficiency was between 80 % and 95 % over the entire operating range.