1.4 Coordinate Transforms

Through a series of coordinate transforms, the user can indirectly determine and control the time invariant values of torque and flux with classic PI control loops.

The process begins by measuring the three-phase motor currents. In practice, the instantaneous sum of the three current values is zero. Therefore, by measuring only two of the three currents, one can determine the third. Due to this fact, hardware cost can be reduced by the expense of the third current sensor.