nuttx/libs/libdsp/lib_transform.c

150 lines
4.7 KiB
C

/****************************************************************************
* libs/libdsp/lib_transform.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <dsp.h>
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: clarke_transform
*
* Description:
* Clarke transform (abc frame -> ab frame).
* Transform the abc frame to the alpha-beta frame.
*
* i_alpha = k*(i_a - 0.5*i_b - 0.5*i_c)
* i_beta = k*sqrt(3)*0.5*(i_b - i_c)
*
* We assume that:
* 1) k = 2/3 for the non-power-invariant transformation
* 2) balanced system: a + b + c = 0
*
* Input Parameters:
* abc - (in) pointer to the abc frame
* ab - (out) pointer to the alpha-beta frame
*
* Returned Value:
* None
*
****************************************************************************/
void clarke_transform(FAR abc_frame_f32_t *abc,
FAR ab_frame_f32_t *ab)
{
LIBDSP_DEBUGASSERT(abc != NULL);
LIBDSP_DEBUGASSERT(ab != NULL);
ab->a = abc->a;
ab->b = ONE_BY_SQRT3_F*abc->a + TWO_BY_SQRT3_F*abc->b;
}
/****************************************************************************
* Name: inv_clarke_transform
*
* Description:
* Inverse Clarke transform (ab frame -> abc frame).
* Transform the alpha-beta frame to the abc frame.
*
* Input Parameters:
* ab - (in) pointer to the alpha-beta frame
* abc - (out) pointer to the abc frame
*
* Returned Value:
* None
*
****************************************************************************/
void inv_clarke_transform(FAR ab_frame_f32_t *ab,
FAR abc_frame_f32_t *abc)
{
LIBDSP_DEBUGASSERT(ab != NULL);
LIBDSP_DEBUGASSERT(abc != NULL);
/* Assume non-power-invariant transform and balanced system */
abc->a = ab->a;
abc->b = -0.5f*ab->a + SQRT3_BY_TWO_F*ab->b;
abc->c = -abc->a - abc->b;
}
/****************************************************************************
* Name: park_transform
*
* Description:
* Park transform (ab frame -> dq frame).
* Transform the alpha-beta frame to the direct-quadrature frame.
*
* Input Parameters:
* angle - (in) pointer to the phase angle data
* ab - (in) pointer to the alpha-beta frame
* dq - (out) pointer to the direct-quadrature frame
*
* Returned Value:
* None
*
****************************************************************************/
void park_transform(FAR phase_angle_f32_t *angle,
FAR ab_frame_f32_t *ab,
FAR dq_frame_f32_t *dq)
{
LIBDSP_DEBUGASSERT(angle != NULL);
LIBDSP_DEBUGASSERT(ab != NULL);
LIBDSP_DEBUGASSERT(dq != NULL);
dq->d = angle->cos * ab->a + angle->sin * ab->b;
dq->q = angle->cos * ab->b - angle->sin * ab->a;
}
/****************************************************************************
* Name: inv_park_transform
*
* Description:
* Inverse Park transform (dq frame -> ab frame).
* Transform direct-quadrature frame to alpha-beta frame.
*
* Input Parameters:
* angle - (in) pointer to the phase angle data
* dq - (in) pointer to the direct-quadrature frame
* ab - (out) pointer to the alpha-beta frame
*
* Returned Value:
* None
*
****************************************************************************/
void inv_park_transform(FAR phase_angle_f32_t *angle,
FAR dq_frame_f32_t *dq,
FAR ab_frame_f32_t *ab)
{
LIBDSP_DEBUGASSERT(angle != NULL);
LIBDSP_DEBUGASSERT(dq != NULL);
LIBDSP_DEBUGASSERT(ab != NULL);
ab->a = angle->cos * dq->d - angle->sin * dq->q;
ab->b = angle->cos * dq->q + angle->sin * dq->d;
}