SENSORLESS FIELD ORIENTED CONTROL OF BRUSHLESS ...

a a s a a
Figure 3.16 – Single-phase equivalent circuit.
V RI jL I E
(3.23)
The standard electrical phasor diagram for phase-A is shown in Figure 3.17 for an arbitrary
lagging power factor. The current phasor is drawn with a hollow arrow head and the bEMF is
always taken to be the reference phasor.
Figure 3.17 – Time phasor diagram of phase-A.
The other two phases have identical diagrams, except each is displaced by 120° to give the
positive sequence rotation (A-B-C) as shown for the general phasor quantities X in Figure 3.18.
In the SPE analysis the phase designation (here, ‘a’) is not typically used but this report uses the
subscript because it will help illustrate the connection between phasors and space vectors later on.
Figure 3.18 – Positive sequence phasor orientation.
Since there are several definitions of a phasor the definition used in this report is given here for
clarity. The bEMF in Equation (3.24) is shown in its phasor representation in Equation (3.25); the
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