CMSIS-DSP: Vector Inverse Park transform

| CMSIS-DSP Version 1.4.7 CMSIS DSP Software Library

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Vector Inverse Park transform
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## Functions
static __INLINE void | arm_inv_park_f32 (float32_t Id, float32_t Iq, float32_t *pIalpha, float32_t *pIbeta, float32_t sinVal, float32_t cosVal)
| Floating-point Inverse Park transform.
static __INLINE void | arm_inv_park_q31 (q31_t Id, q31_t Iq, q31_t *pIalpha, q31_t *pIbeta, q31_t sinVal, q31_t cosVal)
| Inverse Park transform for Q31 version.

## Description

Inverse Park transform converts the input flux and torque components to two-coordinate vector.

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 `pIalpha` and `pIbeta` are the stator vector components, `Id` and `Iq` are rotor vector components and `cosVal` and `sinVal` are the cosine and sine values of theta (rotor flux position).

Fixed-Point Behavior
  Care must be taken when using the Q31 version of the Park 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.

## Function Documentation

static __INLINE void arm_inv_park_f32 | ( | float32_t | Id,
|  | float32_t | Iq,
|  | float32_t * | pIalpha,
|  | float32_t * | pIbeta,
|  | float32_t | sinVal,
|  | float32_t | cosVal
| ) |  |
| static

Parameters

  [in] | Id | input coordinate of rotor reference frame d
  [in] | Iq | input coordinate of rotor reference frame q
  [out] | pIalpha | points to output two-phase orthogonal vector axis alpha
  [out] | pIbeta | points to output two-phase orthogonal vector axis beta
  [in] | sinVal | sine value of rotation angle theta
  [in] | cosVal | cosine value of rotation angle theta

static __INLINE void arm_inv_park_q31 | ( | q31_t | Id,
|  | q31_t | Iq,
|  | q31_t * | pIalpha,
|  | q31_t * | pIbeta,
|  | q31_t | sinVal,
|  | q31_t | cosVal
| ) |  |
| static

Parameters

  [in] | Id | input coordinate of rotor reference frame d
  [in] | Iq | input coordinate of rotor reference frame q
  [out] | pIalpha | points to output two-phase orthogonal vector axis alpha
  [out] | pIbeta | points to output two-phase orthogonal vector axis beta
  [in] | sinVal | sine value of rotation angle theta
  [in] | cosVal | cosine value of rotation angle theta

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 addition, hence there is no risk of overflow.