Core-loss analysis in ac inductors for a single-phase pulse-width modulated solar power conditioner

This paper presents theoretical analysis and experimental verification of the core loss in ac inductors for a three-phase solar power conditioner. The solar power conditioner is characterized by the control method based on single-phase PWM control method, which turns on or off only one of the three phase legs in each PWM-carrier period. Since the average switching frequency is reduced by a factor of three, the single-phase PWM control method enables the inverter to decrease not only switching losses in the switching devices but also core losses in the ac inductors, compared with a conventional three-phase PWM method. The theoretical analysis clarify that the eddy-current power loss can be reduced to 60% of that in a conventional three-phase PWM control method. Experimental results obtained by a 3-kW, 200-V setup is shown to verify the validity of the analysis and to demonstrates a good efficiency as high as 99.2%.