Additional SVM variations

motor/foc_math.c

@@ -196,6 +196,10 @@ void foc_pll_run(float phase, float dt, float *phase_var,
 /**
  * @brief svm Space vector modulation. Magnitude must not be larger than sqrt(3)/2, or 0.866 to avoid overmodulation.
  * See https://github.com/vedderb/bldc/pull/372#issuecomment-962499623 for a full description.
+ * Null=V0 variation (reduces switching losses by up to 33%)
+ * See the follwoing links for a full description: 
+ * https://youtu.be/5eQyoVMz1dY
+ * https://go.gale.com/ps/i.do?id=GALE%7CA18320578&sid=sitemap&v=2.1&it=r&p=AONE&sw=w&userGroupName=anon%7E469317a7
  * @param alpha voltage
  * @param beta Park transformed and normalized voltage
  * @param PWMFullDutyCycle is the peak value of the PWM counter.
@@ -205,128 +209,87 @@ void foc_pll_run(float phase, float dt, float *phase_var,
  */
 void foc_svm(float alpha, float beta, uint32_t PWMFullDutyCycle,
  uint32_t* tAout, uint32_t* tBout, uint32_t* tCout, uint32_t *svm_sector) {
- uint32_t sector;
-
- if (beta >= 0.0f) {
- if (alpha >= 0.0f) {
- //quadrant I
- if (ONE_BY_SQRT3 * beta > alpha) {
- sector = 2;
- } else {
- sector = 1;
- }
- } else {
- //quadrant II
- if (-ONE_BY_SQRT3 * beta > alpha) {
- sector = 3;
- } else {
- sector = 2;
- }
- }
- } else {
- if (alpha >= 0.0f) {
- //quadrant IV5
- if (-ONE_BY_SQRT3 * beta > alpha) {
- sector = 5;
- } else {
- sector = 6;
- }
- } else {
- //quadrant III
- if (ONE_BY_SQRT3 * beta > alpha) {
- sector = 4;
- } else {
- sector = 5;
- }
- }
- }
-
- // PWM timings
- uint32_t tA, tB, tC;
-
- switch (sector) {
 
- // sector 1-2
+ uint32_t sector;
+ float angle, T1, T2, magnitude, temp;
+ uint32_t tA, tB, tC; // PWM timings
+
+ // get angle
+#ifdef USE_MATH_H
+ angle = atan2f(beta, alpha);
+#else
+ // using onboard dsp (requires at least v1.10.0 of the cmsis lib)
+ // https://github.com/ARM-software/CMSIS-DSP/releases
+ // 
+ (void)arm_atan2_f32(beta, alpha, &angle);
+#endif
+
+ // convert from (-pi, pi) to (0, 2*pi) via branchless programming
+ angle = angle + (angle < 0.0f)*SIX_PI_OVER_3;
+ sector = ((uint32_t)(angle / PI_OVER_3) % 6u) + 1u;
+ angle = fmodf(angle, PI_OVER_3); // from math.h
+
+ // determine magnitude
+#ifdef USE_MATH_H
+ magnitude = hypotf(alpha, beta);
+#else
+ // using onboard dsp
+ (void)arm_sqrt_f32(SQ(alpha)+SQ(beta), &magnitude);
+#endif
+
+ // temporary variable for intermediate math
+ temp = (float)PWMFullDutyCycle * magnitude * TWO_BY_SQRT3;
+
+#ifdef USE_MATH_H
+ T1 = temp * sinf(PI_OVER_3 - angle);
+ T2 = temp * sinf(angle);
+#else
+ // using onboard dsp
+ T1 = temp * arm_sin_f32(PI_OVER_3 - angle);
+ T2 = temp * arm_sin_f32(angle);
+#endif
+
+
+ switch(sector) {
  case 1: {
- // Vector on-times
- uint32_t t1 = (alpha - ONE_BY_SQRT3 * beta) * PWMFullDutyCycle;
- uint32_t t2 = (TWO_BY_SQRT3 * beta) * PWMFullDutyCycle;
-
- // PWM timings
- tA = (PWMFullDutyCycle + t1 + t2) / 2;
- tB = tA - t1;
- tC = tB - t2;
-
+ tA = (uint32_t)(T1+T2);
+ tB = (uint32_t)(T2);
+ tC = (uint32_t)(0);
  break;
  }
-
- // sector 2-3
+
  case 2: {
- // Vector on-times
- uint32_t t2 = (alpha + ONE_BY_SQRT3 * beta) * PWMFullDutyCycle;
- uint32_t t3 = (-alpha + ONE_BY_SQRT3 * beta) * PWMFullDutyCycle;
-
- // PWM timings
- tB = (PWMFullDutyCycle + t2 + t3) / 2;
- tA = tB - t3;
- tC = tA - t2;
-
+ tA = (uint32_t)(T1);
+ tB = (uint32_t)(T1+T2);
+ tC = (uint32_t)(0);
  break;
  }
-
- // sector 3-4
+
  case 3: {
- // Vector on-times
- uint32_t t3 = (TWO_BY_SQRT3 * beta) * PWMFullDutyCycle;
- uint32_t t4 = (-alpha - ONE_BY_SQRT3 * beta) * PWMFullDutyCycle;
-
- // PWM timings
- tB = (PWMFullDutyCycle + t3 + t4) / 2;
- tC = tB - t3;
- tA = tC - t4;
-
+ tA = (uint32_t)(0);
+ tB = (uint32_t)(T1+T2);
+ tC = (uint32_t)(T2);
  break;
  }
-
- // sector 4-5
+
  case 4: {
- // Vector on-times
- uint32_t t4 = (-alpha + ONE_BY_SQRT3 * beta) * PWMFullDutyCycle;
- uint32_t t5 = (-TWO_BY_SQRT3 * beta) * PWMFullDutyCycle;
-
- // PWM timings
- tC = (PWMFullDutyCycle + t4 + t5) / 2;
- tB = tC - t5;
- tA = tB - t4;
-
+ tA = (uint32_t)(0);
+ tB = (uint32_t)(T1);
+ tC = (uint32_t)(T1+T2);
  break;
  }
-
- // sector 5-6
+
  case 5: {
- // Vector on-times
- uint32_t t5 = (-alpha - ONE_BY_SQRT3 * beta) * PWMFullDutyCycle;
- uint32_t t6 = (alpha - ONE_BY_SQRT3 * beta) * PWMFullDutyCycle;
-
- // PWM timings
- tC = (PWMFullDutyCycle + t5 + t6) / 2;
- tA = tC - t5;
- tB = tA - t6;
-
+ tA = (uint32_t)(T2);
+ tB = (uint32_t)(0);
+ tC = (uint32_t)(T1+T2);
  break;
  }
-
- // sector 6-1
+
  case 6: {
- // Vector on-times
- uint32_t t6 = (-TWO_BY_SQRT3 * beta) * PWMFullDutyCycle;
- uint32_t t1 = (alpha + ONE_BY_SQRT3 * beta) * PWMFullDutyCycle;
-
- // PWM timings
- tA = (PWMFullDutyCycle + t6 + t1) / 2;
- tC = tA - t1;
- tB = tC - t6;
-
+ tA = (uint32_t)(T1+T2);
+ tB = (uint32_t)(0);
+ tC = (uint32_t)(T1);
  break;
  }
  }

motor/foc_math.h

@@ -20,6 +20,13 @@
 #ifndef FOC_MATH_H_
 #define FOC_MATH_H_
 
+// comment this to enable usage of the onboard dsp
+#define USE_MATH_H
+
+#ifndef USE_MATH_H
+#include <arm_math.h>
+#endif
+
 #include "datatypes.h"
 
 // Types

util/utils_math.h

@@ -119,6 +119,8 @@ void utils_rotate_vector3(float *input, float *rotation, float *output, bool rev
 #define COS_MINUS_30_DEG (0.86602540378)
 #define SIN_MINUS_30_DEG (-0.5)
 #define ONE_BY_SQRT2 (0.7071067811865475)
+#define PI_OVER_3 (1.0471975511965977f) // 60 degrees
+#define SIX_PI_OVER_3 (6.0f*PI_OVER_3) // 360 degrees
 
 // Tables
 extern const float utils_tab_sin_32_1[];