Vector Inverse Clarke TransformΒΆ

__STATIC_FORCEINLINE void riscv_inv_clarke_f32(float32_t Ialpha, float32_t Ibeta, float32_t * pIa, float32_t * pIb)
__STATIC_FORCEINLINE void riscv_inv_clarke_q31(q31_t Ialpha, q31_t Ibeta, q31_t * pIa, q31_t * pIb)
group inv_clarke

Inverse Clarke transform converts the two-coordinate time invariant vector into instantaneous stator phases.

end of clarke group The function operates on a single sample of data and each call to the function returns the processed output. The library provides separate functions for Q31 and floating-point data types.

Algorithm

where

pIa and pIb are the instantaneous stator phases and Ialpha and Ibeta are the two coordinates of time invariant vector. ../../../_images/clarkeInvFormula.png

Fixed-Point Behavior

Care must be taken when using the Q31 version of the Clarke transform. In particular, the overflow and saturation behavior of the accumulator used must be considered. Refer to the function specific documentation below for usage guidelines.

Functions

__STATIC_FORCEINLINE void riscv_inv_clarke_f32(float32_t Ialpha, float32_t Ibeta, float32_t * pIa, float32_t * pIb)

Floating-point Inverse Clarke transform.

Return

none

Parameters
  • [in] Ialpha: input two-phase orthogonal vector axis alpha

  • [in] Ibeta: input two-phase orthogonal vector axis beta

  • [out] pIa: points to output three-phase coordinate a

  • [out] pIb: points to output three-phase coordinate b

__STATIC_FORCEINLINE void riscv_inv_clarke_q31(q31_t Ialpha, q31_t Ibeta, q31_t * pIa, q31_t * pIb)

Inverse Clarke transform for Q31 version.

Return

none

Scaling and Overflow Behavior

The function is implemented using an internal 32-bit accumulator. The accumulator maintains 1.31 format by truncating lower 31 bits of the intermediate multiplication in 2.62 format. There is saturation on the subtraction, hence there is no risk of overflow.

Parameters
  • [in] Ialpha: input two-phase orthogonal vector axis alpha

  • [in] Ibeta: input two-phase orthogonal vector axis beta

  • [out] pIa: points to output three-phase coordinate a

  • [out] pIb: points to output three-phase coordinate b