2.1.1 Clarke Transformation

The Clarke Transformation transforms the electrical signals from the three-axis reference frame (abc) to the two-axis orthogonal reference frame (αβ) as shown in the following figure.

Figure 2-2. Clarke Transformation

The transform is expressed by the following equations:

i a + i b + i c = 0
i α = i a
i β = 1 3 ( i b i c )

Where:

iα, ib and ic are the three-phase currents in abc reference frame, iα and iβ are the two-phase orthogonal currents in the αβ reference frame.