Electrical Machines And Drives A Space Vector Theory Approach Monographs In Electrical And Electronic Engineering Exclusive • Plus

For PMSM drives, specifically Interior Permanent Magnet (IPM) machines, Space Vector Theory is vital for maximizing torque per ampere (MTPA). The interaction between the magnetic flux of the permanent magnets and the reluctance torque (due to the saliency of the rotor) creates a complex control surface. Only through $d-q$ axis vector control can these torques be optimized simultaneously, a feat impossible with scalar V/f control.

Electrical Machines and Drives: A space-vector theory approach There is one text that answers this question

Traditional scalar control (V/f control) treats voltage, current, and flux as sinusoidal quantities varying in time. It works for fans and pumps but fails spectacularly under high dynamic loads. Space vector theory, however, reimagines three-phase quantities as a single rotating complex vector in a stationary or rotating reference frame (d-q axes). Oxford University Press).

There is one text that answers this question definitively: (Part of the Monographs in Electrical and Electronic Engineering series, Oxford University Press). For PMSM drives