three phase transformerless AC to DC power converter

hello everybody!! I am working on a digital circuit that will be used to measure a three phase AC voltage. The circuit will measure Line1 to neutral AC voltage, Line2 to neutral AC voltage, Line3 to neutral AC voltage. I intend to do this by rectifying and converting the signal into a dc voltage (without the use of a transformer) after which I will feed these signals into an ADC and then input these the digital signals to an 89C51 microcontroller and display the readings into an LCD.

Could anyone give me tips or better suggestion on how could I convert/rectify a three phase AC voltage into a dc voltage....

I really need all the help I could get....

thanks in advance!!!