Research of a single-stage buck-boost inverter under dual mode modulation

The output voltage range of photovoltaic (PV) cell is widely influenced by the light, temperature and so on. The inverter used in PV system must achieve inversion with a wide range of DC input voltage. A single-stage buck-boost inverter with fewer inductors and capacitors is proposed in this paper based on the topology of full bridge+Boost AC/AC, which is just suitable for PV system, achieving inversion and boosting with a wide range of input. Two modulation methods are compared: constant step-up ratio modulation and dual mode modulation. Along with the relationship of the input DC voltage and the reference AC voltage, the converter complete buck or boost inversion with different equivalent circuits and there are fewer switches working at high frequency in dual mode modulation, which is in favor of the system with high efficiency. Simulation and experimental results are presented to verify the proposed topology can achieve dual mode operation with wide range of input voltage in single-stage power conversion.