Evaluation of DC link capacitor for solar fed dual inverter with zero sequence elimination PWM

Abstract

In an Inverter, the purpose of DC link capacitor is to maintain the stiff DC bus voltage irrespective of the switching disturbance by providing alternative path for the switching ripple current. To design the capacitor for an inverter the expression for the RMS current ripple at DC link need be computed based on the switching algorithm and load connected with the inverter. In this work, the capacitor requirement for the dual two level inverter configuration operated with zero sequence voltage elimination algorithm is evaluated as in this algorithm full DC bus voltage would appear across the AC phase terminals resulting high dv/dt across AC terminals. The current ripple due to dv/dt is computed in this work by considering the AC current flows through load is pure sinusoidal. Based on the computed current ripple, the appropriate DC link capacitor is identified to maintain the stiff DC bus voltage across the dual inverter configuration. The efficacy of the DC link capacitor computed using theoretical expression is validated through MATLAB simulations. Through the MATLAB simulations it is verified that the current ripple RMS value derived from the theoretical expression is closely matches with the simulation result.