The inductor smoothes to some degree, and the capacitor does the same.
Choose the inductor value so it starts the rolloff curve, at your load Amperage, about 1.5 to 2x your fundamental frequency.
The inductor causes a phase shift of current in the PWM source. This creates a power factor error. Therefore you need the capacitor to cause a phase shift in the opposite direction. Together they provide power factor correction.
If the inductor is too small, you get insufficient smoothing of the output waveform. If the inductor is too large, it starts to act as a choke which attenuates the output amplitude.