Vector Inverse Park transform

Functions
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. More...
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. More...

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

arm_inv_park_f32()

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

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

Returns

none

arm_inv_park_q31()

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

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

Returns

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 addition, hence there is no risk of overflow.