Why do three-phase motors require the use of U, V, and W wires?

A three-phase motor requires the use of U, V, and W wires because it is a motor driven by a three-phase AC power supply. Each phase requires a power cord and a corresponding grounding wire. In a three-phase electrical system, U, V, and W lines are connected to three different phases with a phase difference of 120 degrees, which can generate a rotating magnetic field and drive the motor to rotate. Therefore, three-phase motors require the use of U, V, and W wires to operate properly.

There are three windings on the stator of a three-phase motor. By applying three-phase currents with phase sequence of 0 °, 120 °, and 240 °, a rotating magnetic field can be generated in the stator space to make the motor rotor operate.
The earliest people labeled the ends of three windings with U-x, V-y, and W-z. This annotation is only in alphabetical order and has no further meaning, and has been used to this day. When only U, V, and W are used, it indicates that the three-phase winding of the motor is connected in a Y-shape (the other end x, y, and z of the three windings are connected to a common end, marked as 0 or N).