end of clarke group
Inverse Clarke transform converts the two-coordinate time invariant vector into instantaneous stator phases.
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.
- 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.
- 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 |
- Returns
- none
__STATIC_FORCEINLINE void arm_inv_clarke_q31 |
( |
q31_t |
Ialpha, |
|
|
q31_t |
Ibeta, |
|
|
q31_t * |
pIa, |
|
|
q31_t * |
pIb |
|
) |
| |
- 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 |
- 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 subtraction, hence there is no risk of overflow.