The power coming into a home is single phase. Thus, at any given point in time, you have constant high voltage. When one supply crosses zero, one of the other supplies is always at the highest point of its arc. By offsetting the power supplies you are able to compensate for zero crossing. If the positive end of the wave is the beginning, the zero crossing is the middle, and the negative end of the wave is the end. You have 3 power supplies and each power supply is offset. Thus, one group is always at the beginning of the song, one at the middle, and one at the end. A third group waits until the second group reaches the agreed upon point and then starts in. The second group waits until the first group reaches an agreed upon point in the song and then starts singing. Have you ever sung a round? When you sing a round, you usually divide your group of singers into thirds. This zero crossing creates the need for 3 phase electricity and, by extension, the need for a 3 phase converter. Thus every time the electrons pass zero, there is no voltage present. When they pass the zero, they have no charge, so they are not c If we graphed this polarity change with negative below the zero point on the graph and the positive above the zero, then as you chart the path of the electrons as they move toward the positive and then back to the negative, you would see that they cross the zero line of the graph again and again. Instead, the electricity is constantly in flux, changing polarity from positive to negative. The electricity in an AC current is not uniformly positive or negative.

3 phase power converter