A single-phase PWM inverter is fed from a smooth 400V dc supply. The PWM modulation index is 0.6 and the fundamental output frequency is 40Hz. The most significant harmonic components in the output voltage spectrum are the 18th and 22nd whose amplitudes are 70% and 50% of the fundamental respectively. All other voltage harmonics may be considered to be negligible. The harmonic distortion in the load current is negligible and the fundamental component, which has a value of 20A (rms), lags the voltage by 40^o.

i) Determine the rms fundamental load voltage.

ii) Determine the frequency components present in the dc side current spectrum and determine the rms value of each component. Stating any assumptions that you may make, estimate the contribution to the rms ripple current in the DC link capacitor due to the inverter switching.