Cascaded Bidirectional Converter Topology for 700 W Transformerless High Frequency Inverter

Home inverter is an important system which provides uninterrupted power supply for domestic requirements. Most of the existing systems use line frequency transformers to generate the desired sinusoidal voltage and exhibit poor load regulation and efficiency. Under spurious conditions, reliable and stable operation of the inverter is a primary requirement. In this paper, 3-stage bidirectional (boost and buck) cascaded converter topology is proposed to boost an input battery voltage from 12 to 375 V and vice-versa. DC link is connected to H-bridge converter to obtain a desired sinusoidal output voltage. In the topology, first and third stages are non-isolated boost converters and second stage is a buck derived push–pull converter. Push–pull configuration of the 2nd stage provides electrical isolation to source from high voltage DC bus. Cascaded DC–DC converter outputs are regulated by designing an average current mode control and instantaneous voltage control is designed for H-bridge inverter. Hardware is designed and developed using digital signal controllers to supply 700 W domestic load. Experiments are conducted for different linear, nonlinear and dynamic load variations.