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.
