If a single phase AC circuit is directed through a bridge rectifier, then DC ripple is created. If a 3 phase transformer is directed through a series of bridge rectifiers, then the DC ripple created becomes much smoother and the RMS voltage becomes much higher has the ripple no longer falls to zero but more to around 80%. If a star and delta transformer is connected through a series of rectifiers, the star and delta power is 90% out of phase. This there by allows more ripples to be generated and the DC ripple only falls to about 95%. I have set this scenario up. The top represents the delta 3 phase transformer and the lower represents the star. I've set the top 3 supplies 120 degrees apart starting at 0 degrees and the bottom is also 130 degrees apart , however, starting at 90 degrees. You can switch the supplies on and off to see the individual phases effect on the DC ripple. This is the basic theory behind how we generate a DC supply to our mine hoisting motors.
