As a control strategy used in variable frequency drives, vector control provides a feasible solution to
torque/speed control of AC machines by controlling the phase currents into the machine even if it gives
rise to a considerable computation burden for the processor where the control algorithms are implemented.
The most noticeable merit of vector control is to get rid of machine speed dependency on power grid frequency
and make it possible to reach the desired machine speed within safety and power limits.
Usually in a vector control system, the phase currents of the machine and the DC-link voltage of the
inverter and sometimes the rotor shaft position and/or the machine speed are taken as the control system
inputs, while the phase voltages to the machine are picked as the outputs. Two important transformations
are involved in the vector control system to transform AC machine into a separately magnetized DC machine,
namely Clarke Transformation and Park Transformation.With these transformations the three-phase
sinusoidal quantities can be transformed into DC quantities in steady state.