Analytical evaluation of the peak-to-peak ripple current in the filter inductor for a space vector modulated grid-tied VSI

Two level voltage source inverters are extensively employed to integrate renewable energy sources and storage with the grid. The output voltage of the inverter, modulated with conventional space vector PWM, contains switching frequency components along with the desired grid frequency component. Usually a filter inductor or an LCL filter is used to remove these high frequency components resulting in low THD in the grid current. Either all, or a majority of the higher frequency components of the inverter output voltage appear across the inverter-side filter inductance, resulting in ripple current through it. This paper presents an analytical estimation of the peak-to-peak ripple current as a function of the modulation index, essential for the design of the filter. Simulation results confirm the analytical prediction of the ripple current.