Benefits
Lower speed and torque ripple
Smoother operation
Operation at higher speeds through field weakening
These benefits come at the cost of implementing a more complex control algorithm than the 6-step commutation.
We know that when the rotor and stator field are aligned perfectly, no torque is produced. However, as the angle between them increases, we start generating torque. When the rotor and stator fields are perpendicular, we get maximum torque. The goal is to keep them perpendicular at all times.
FOC Algorithm
Measure rotor angular position
Compute the desired stator field vector based on measured rotor angular position
Control 3-phase currents to achieve the desired stator field vector
