Q: What is Field Oriented Control (FOC) and how to implement it on STM32?
Answer
FOC (Field Oriented Control) for PMSM/BLDC achieves DC motor-like performance with AC motor efficiency. Principle: transform 3-phase currents into rotating DQ reference frame aligned with rotor flux. Transforms: Clarke (3-phase -> 2-phase) then Park (2-phase -> DQ rotating). DQ control: D-axis current controls flux (keep at zero for MTPA) Q-axis current controls torque. Use SVPWM to convert voltage vectors back to 3-phase PWM. Implementation on STM32: (1) Read 3-phase currents via ADC (shunt resistor + OpAmps). (2) Get rotor angle from encoder/Hall/sensorless observer. (3) Run Clarke+Park transform. (4) PI controllers for Id and Iq. (5) Inverse Park transform. (6) SVPWM generation via timer. Run at 10-20 kHz PWM. STM32F3/F7/H7 have hardware cordic accelerator for sin/cos. Use the X-Cube-MCSDK (Motor Control SDK) which provides complete FOC software with sensorless observer (SMO or PLL).
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