DSP Builder for Intel® FPGAs (Advanced Blockset): Handbook

ID 683337
Date 12/12/2022

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7.6.3. About FOC

FOC involves controlling the motor's sinusoidal 3-phase currents in real time, to create a smoothly rotating magnetic flux pattern, where the frequency of rotation corresponds to the frequency of the sine waves. FOC controls the amplitude of the current vector that is at 90 degrees with respect to the rotor magnet flux axis (quadrature current) to control torque.

The direct current component (0 degrees) is set to zero. The algorithm involves the following steps:

  • Converting the 3-phase feedback current inputs and the rotor position from the encoder into quadrature and direct current components with the Clarke and Park transforms.
  • Using these current components as the inputs to two proportional and integral (PI) controllers running in parallel to control the direct current to zero and the quadrature current to the desired torque.
  • Converting the direct and quadrature current outputs from the PI controllers back to 3-phase currents with inverse Clarke and Park transforms.