SENSORLESS FIELD ORIENTED CONTROL OF BRUSHLESS ...

stator’s perspective and at R
from the rotor’s perspective. The SV in the stator frame is
S R
r
ahead of the rotor frame, so if the SV in the stator frame is rotated by the negative
of this angle, it is exactly the SV we would see from the rotor frame perspective. That is, if we
rotate the SV by r
we will see from the stator the exact SV the rotor sees (a SV at position
R
). This is the vector rotation perspective and is illustrated in Figure 3.36, where the “grabbing
hand” symbol indicates vector rotation.
Figure 3.36 – Park transform: vector rotation perspective.
In coordinate rotation perspective the position of the SV is thought of as remaining fixed and the
coordinate system is rotated by r
instead of r
. This is shown in Figure 3.37, where the
“grabbing hand” symbol indicates coordinate rotation.
Figure 3.37 – Park transform: coordinate rotation perspective.
Coordinate rotation is the better perspective because we are seeking to describe a SV from a
different coordinate system, not control the position of the SV. In contrast, a vector controlled
drive seeks to control the position of a SV (such as the stator current SV). An interpretation that is
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