SENSORLESS FIELD ORIENTED CONTROL OF BRUSHLESS ...

Figure 5.30 – Top-level model of rotor-oriented FOC.
In FOC the synchronous regulator operates in the rotor frame, thus the motor should be modeled
in the same. From Chapter 3, the dq simulation diagram of the motor is given as Figure 5.31. The
figure would normally also show the inverter gain but it is assumed to be unity here; the entire
figure corresponds to the block in Figure 5.30.
Figure 5.31 – Simulation diagram for BPMS motor in synchronous frame.
At this time the ability of FOC to separately control the dq components (as discussed in this
chapter) should be contrasted with the coupling discussed in Chapter 3 and shown in Figure 5.31.
The FOC topology is able to separately control the dq current components (because control is
exercised in the rotor frame) and this allows direct torque control. However, the dynamics of the
component currents are coupled inside the motor, thus it is not true that FOC offers “completely
decoupled” control of the stator current components, as some references will insinuate.
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