Wheel System, Traction411Service Manual – CS7000Drive MotorThe drive controller supplies current to the drive motor stator windings on the three large U, V and W wires.When stationary, the controller pulses a current to all the motor stator windings in “unison”. This holds themotor in a fixed position. To make the motor rotate, the controller shifts the timing, duration, and currentof each of the windings. This continuously changes the location and strength of the magnetic field polescreated by the stator windings, which causes torque to be applied to the rotor.Below is an oscilloscope waveform that shows the 3 phases of the motor (U, V and W) when the motor isstationary. You can see how all 3 phases are being pulsed in unison. The vertical position of each trace wasadjusted to separate them for better clarity. Other wise all three would blend together as a single trace.Below is an oscilloscope waveform that shows the 3 phases of the motor (U, V and W) when the motor ismoving forward. You can see how each phase is now unique and no longer in unison. Again, the verticalposition of each trace was adjusted to separate them for better clarity.WaveStar : NotesSheet(11) Page: 1Drive Motor U,V and W - StationaryWaveStar : NotesSheet(12) Page: 1Drive Motor U,V and W - Moving Forward
