Explain Field-Oriented Control (FOC) and its implementation in EV motor drives.

FOC (vector control) transforms AC motor control into a DC-like problem by decomposing stator current into flux-producing (Id) and torque-producing (Iq) components using Park/Clarke transforms. For PMSM, Id is typically zero (maximum torque per ampere), while Iq is controlled for torque demand. At high speeds, field weakening (negative Id) extends speed range beyond base speed. Implementation requires accurate rotor position sensing (resolver/encoder) or sensorless estimation, high-bandwidth current loops (10+ kHz), and precise PWM generation. Advanced techniques include MTPA (Maximum Torque Per Ampere) and MTPV (Maximum Torque Per Volt) strategies.