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本帖最后由 zddvszw 于 2014-7-16 11:20 编辑
最近在研究SVPWM，不明白T0为什么要除以2 ，以下是代码，有做过的朋友帮我解释下咯，小弟在此感谢了。
#include <p30f6010.h>
#include "svm.h"
//---------------------------------------------------------------------
// These are the definitions for various angles used in the SVM
// routine. A 16-bit unsigned value is used as the angle variable.
// The SVM algorithm determines the 60 degree sector
#define VECTOR1 0 // 0 degrees
#define VECTOR2 0x2aaa // 60 degrees
#define VECTOR3 0x5555 // 120 degrees
#define VECTOR4 0x8000 // 180 degrees
#define VECTOR5 0xaaaa // 240 degrees
#define VECTOR6 0xd555 // 300 degrees
#define SIXTY_DEG 0x2aaa
//---------------------------------------------------------------------
// This is the maximum value that may be passed to the SVM
// function without overmodulation. This limit is equivalent
// to 0.866, which is sqrt(3)/2.
#define VOLTS_LIMIT 28300
// This sinewave lookup table has 171 entries. (1024 points per
// electrical cycle -- 1024*(60/360) = 171)
// The table covers 60 degrees of the sine function.
int sinetable[] = {0,201,401,602,803,1003,1204,1404,1605,1805,
2005,2206,2406,2606,2806,3006,3205,3405,3605,3804,4003,4202,4401,4600,
4799,4997,5195,5393,5591,5789,5986,6183,6380,6577,6773,6970,7166,7361,
7557,7752,7947,8141,8335,8529,8723,8916,9109,9302,9494,9686,9877,10068,
10259,10449,10639,10829,11018,11207,11395,11583,11771,11958,12144,
12331,12516,12701,12886,13070,13254,13437,13620,13802,13984,14165,
14346,14526,14706,14885,15063,15241,15419,15595,15772,15947,16122,
16297,16470,16643,16816,16988,17159,17330,17500,17669,17838,18006,
18173,18340,18506,18671,18835,18999,19162,19325,19487,19647,19808,
19967,20126,20284,20441,20598,20753,20908,21062,21216,21368,21520,
21671,21821,21970,22119,22266,22413,22559,22704,22848,22992,23134,
23276,23417,23557,23696,23834,23971,24107,24243,24377,24511,24644,
24776,24906,25036,25165,25293,25420,25547,25672,25796,25919,26042,
26163,26283,26403,26521,26638,26755,26870,26984,27098,27210,27321,
27431,27541,27649,27756,27862,27967,28071,28174,28276,28377};
//---------------------------------------------------------------------
// The function SVM() determines which sector the input angle is
// located in. Then, the modulation angle is normalized to the current
// 60 degree sector. Two angles are calculated from the normalized
// angle. These two angles determine the times for the T1 and T2
// vectors. The T1 and T2 vectors are then scaled by the modulation
// amplitude and the duty cycle range. Finally, the T0 vector time
// is the time left over in the PWM counting period.
// The SVM() function then calculates three duty cycle values based
// on the T0, T1, and T2 times. The duty cycle calculation depends
// on the
// appropriate duty cycle values depending on the type of SVM to be
// generated.
//---------------------------------------------------------------------
void SVM(int volts, unsigned int angle)
{
// These variables hold the normalized sector angles used to find
// t1, t2.
unsigned int angle1, angle2;
// These variables hold the space vector times.
unsigned int half_t0,t1,t2,tpwm;
// Calculate the total PWM count period, which is twice the value
// in the PTPER register.
tpwm = PTPER << 1;
// Limit volts input to avoid overmodulation.
if(volts > VOLTS_LIMIT) volts = VOLTS_LIMIT;
if(angle < VECTOR2)
{
angle2 = angle - VECTOR1; // Reference SVM angle to the current sector
angle1 = SIXTY_DEG - angle2; // Calculate second angle referenced to sector
t1 = sinetable[(unsigned char)(angle1 >> 6)]; // Look up values from table.
t2 = sinetable[(unsigned char)(angle2 >> 6)];
// Scale t1 to by the volts variable.
t1 = ((long)t1*(long)volts) >> 15;
// Scale t1 for the duty cycle range.
t1 = ((long)t1*(long)tpwm) >> 15;
// Scale t2 time
t2 = ((long)t2*(long)volts) >> 15;
t2 = ((long)t2*(long)tpwm) >> 15;
half_t0 = (tpwm - t1 - t2) >> 1; // Calculate half_t0 null time from period and t1,t2
// Calculate duty cycles for Sector 1 (0 - 59 degrees)
PDC1 = t1 + t2 + half_t0;
PDC2 = t2 + half_t0;
PDC3 = half_t0;
}
else if(angle < VECTOR3)
{
angle2 = angle - VECTOR2; // Reference SVM angle to the current sector
angle1 = SIXTY_DEG - angle2; // Calculate second angle referenced to sector
t1 = sinetable[(unsigned char)(angle1 >> 6)]; // Look up values from table.
t2 = sinetable[(unsigned char)(angle2 >> 6)];
// Scale t1 to by the volts variable.
t1 = ((long)t1*(long)volts) >> 15;
// Scale t1 for the duty cycle range.
t1 = ((long)t1*(long)tpwm) >> 15;
// Scale t2 time
t2 = ((long)t2*(long)volts) >> 15;
t2 = ((long)t2*(long)tpwm) >> 15;
half_t0 = (tpwm - t1 - t2) >> 1; // Calculate half_t0 null time from period and t1,t2
// Calculate duty cycles for Sector 2 (60 - 119 degrees)
PDC1 = t1 + half_t0;
PDC2 = t1 + t2 + half_t0;
PDC3 = half_t0;
}
else if(angle < VECTOR4)
{
angle2 = angle - VECTOR3; // Reference SVM angle to the current sector
angle1 = SIXTY_DEG - angle2; // Calculate second angle referenced to sector
t1 = sinetable[(unsigned char)(angle1 >> 6)]; // Look up values from table.
t2 = sinetable[(unsigned char)(angle2 >> 6)];
// Scale t1 to by the volts variable.
t1 = ((long)t1*(long)volts) >> 15;
// Scale t1 for the duty cycle range.
t1 = ((long)t1*(long)tpwm) >> 15;
// Scale t2 time
t2 = ((long)t2*(long)volts) >> 15;
t2 = ((long)t2*(long)tpwm) >> 15;
half_t0 = (tpwm - t1 - t2) >> 1; // Calculate half_t0 null time from period and t1,t2
// Calculate duty cycles for Sector 3 (120 - 179 degrees)
PDC1 = half_t0;
PDC2 = t1 + t2 + half_t0;
PDC3 = t2 + half_t0;
}
else if(angle < VECTOR5)
{
angle2 = angle - VECTOR4; // Reference SVM angle to the current sector
angle1 = SIXTY_DEG - angle2; // Calculate second angle referenced to sector
t1 = sinetable[(unsigned char)(angle1 >> 6)]; // Look up values from table.
t2 = sinetable[(unsigned char)(angle2 >> 6)];
// Scale t1 to by the volts variable.
t1 = ((long)t1*(long)volts) >> 15;
// Scale t1 for the duty cycle range.
t1 = ((long)t1*(long)tpwm) >> 15;
// Scale t2 time
t2 = ((long)t2*(long)volts) >> 15;
t2 = ((long)t2*(long)tpwm) >> 15;
half_t0 = (tpwm - t1 - t2) >> 1; // Calculate half_t0 null time from period and t1,t2
// Calculate duty cycles for Sector 4 (180 - 239 degrees)
PDC1 = half_t0;
PDC2 = t1 + half_t0;
PDC3 = t1 + t2 + half_t0;
}
else if(angle < VECTOR6)
{
angle2 = angle - VECTOR5; // Reference SVM angle to the current sector
angle1 = SIXTY_DEG - angle2; // Calculate second angle referenced to sector
t1 = sinetable[(unsigned char)(angle1 >> 6)]; // Look up values from table.
t2 = sinetable[(unsigned char)(angle2 >> 6)];
// Scale t1 to by the volts variable.
t1 = ((long)t1*(long)volts) >> 15;
// Scale t1 for the duty cycle range.
t1 = ((long)t1*(long)tpwm) >> 15;
// Scale t2 time
t2 = ((long)t2*(long)volts) >> 15;
t2 = ((long)t2*(long)tpwm) >> 15;
half_t0 = (tpwm - t1 - t2) >> 1; // Calculate half_t0 null time from period and t1,t2
// Calculate duty cycles for Sector 5 (240 - 299 degrees)
PDC1 = t2 + half_t0;
PDC2 = half_t0;
PDC3 = t1 + t2 + half_t0;
}
else
{
angle2 = angle - VECTOR6; // Reference SVM angle to the current sector
angle1 = SIXTY_DEG - angle2; // Calculate second angle referenced to sector
t1 = sinetable[(unsigned char)(angle1 >> 6)]; // Look up values from table.
t2 = sinetable[(unsigned char)(angle2 >> 6)];
// Scale t1 to by the volts variable.
t1 = ((long)t1*(long)volts) >> 15;
// Scale t1 for the duty cycle range.
t1 = ((long)t1*(long)tpwm) >> 15;
// Scale t2 time
t2 = ((long)t2*(long)volts) >> 15;
t2 = ((long)t2*(long)tpwm) >> 15;
half_t0 = (tpwm - t1 - t2) >> 1; // Calculate half_t0 null time from period and t1,t2
// Calculate duty cycles for Sector 6 ( 300 - 359 degrees )
PDC1 = t1 + t2 + half_t0;
PDC2 = half_t0;
PDC3 = t1 + half_t0;
}
} // end SVM()
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发表于 2014-7-16 10:13:10
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