Switched Capacitor Based 13-Level Boosting Grid Connected Inverter with LCL Filter

In this paper, a Switched Capacitor (SC) based thirteen level boosting Grid Connected Inverter ( GCI) with LCL filter has been elucidated vividly. Particularly, the inverter topology comprises one dc source, twelve unidirectional switches, three SCs and four discrete diodes. Based on parallel-series technique, the SCs are self-balanced without need of sensors or separate auxiliary circuits. Before going to grid connection, firstly the proposed Universal Rounding Control Scheme (URCS-Low switching frequency technique) has been applied to the inverter topology with RL load case. This control scheme is also called as non-carrier method and it is basically suitable for large number of level inverter topologies. Using this method, basically the switching losses are greatly reduces as compared with high switching frequency carrier methods. Secondly, in grid connection, an LCL filter has been integrated in between inverter and grid thereby higher ripple attenuation capability along with active damping method has been achieved easily. A separate dq frame current control strategy with Unipolar Phase Disposition (UPD) Pulse Width Modulation (PWM) technique has been applied to the GCI topology. In this, d-axis current reference is used to inject active power into the grid and at a time with zero q-axis current reference, the Unity Power Factor (UPF) operation of the grid has been achieved. Finally, the operation and respective control strategies have been corroborated through MATLAB platform.