F28035 输出三相 SPWM脉冲程序

以下是基于F28035的三相SPWM脉冲程序示例：

首先，需要定义SPWM参数，例如谐波数量、采样频率等。这些参数可以根据具体应用进行调整。

#define PWM_FREQUENCY 20000
#define DEAD_BAND 0
#define MAX_DUTY_CYCLE 0.95
#define MIN_DUTY_CYCLE 0.05
#define PWM_COUNTS ((float)CPUFREQ/PWM_FREQUENCY)
#define DEAD_BAND_COUNTS ((float)CPUFREQ*DEAD_BAND/1000)
#define PWM_PERIOD_COUNTS (PWM_COUNTS-2*DEAD_BAND_COUNTS)
#define ONE_CYCLE_COUNTS (6*PWM_PERIOD_COUNTS)
#define HALF_CYCLE_COUNTS (ONE_CYCLE_COUNTS/2)
#define SAMPLE_FREQUENCY (PWM_FREQUENCY*20)
#define SAMPLE_COUNTS ((float)CPUFREQ/SAMPLE_FREQUENCY)
#define HARMONIC_COUNT 25
#define PI 3.14159265358979323846
#define TWO_PI 6.28318530717958647692

接着，需要定义SPWM函数，用于生成三相SPWM波形。该函数的实现过程如下：

void SPWM(float phase_shift, float amplitude, float frequency, float *sine_table, float *sine_table_index, float *duty_cycle)
{
    float count = 0;
    float sine_value = 0;
    float sine_table_step = (float)SAMPLE_FREQUENCY/frequency;
    float sine_table_index_step = sine_table_step/SAMPLE_COUNTS;
    float phase_shift_counts = phase_shift/360*ONE_CYCLE_COUNTS;
    float sine_table_index_offset = phase_shift_counts/sine_table_index_step;
    float amplitude_counts = amplitude*PWM_PERIOD_COUNTS/3.3;
    float harmonic_amplitude[HARMONIC_COUNT+1] = {0, 0.6667, 0.2, 0.1333, 0.1, 0.08, 0.0667, 0.0571, 0.05, 0.0444, 0.04, 0.0364, 0.0333, 0.0308, 0.0286, 0.0267, 0.025, 0.0235, 0.0222, 0.0211, 0.02, 0.019, 0.0182, 0.0174, 0.0167};

    for(int i = 0; i < PWM_PERIOD_COUNTS; i++)
    {
        count++;

        if(count > sine_table_step)
        {
            count = 1;
            *sine_table_index += sine_table_index_step;

            if(*sine_table_index >= SAMPLE_COUNTS)
            {
                *sine_table_index = 0;
            }
        }

        sine_value = sine_table[(int)(*sine_table_index+sine_table_index_offset)];
        *duty_cycle = 0.5*(amplitude_counts*sine_value/PWM_PERIOD_COUNTS);

        for(int j = 1; j <= HARMONIC_COUNT; j++)
        {
            sine_value = sine_table[(int)(*sine_table_index+sine_table_index_offset)*j];
            *duty_cycle += harmonic_amplitude[j]*(amplitude_counts*sine_value/PWM_PERIOD_COUNTS);
        }

        if(*duty_cycle < MIN_DUTY_CYCLE)
        {
            *duty_cycle = MIN_DUTY_CYCLE;
        }
        else if(*duty_cycle > MAX_DUTY_CYCLE)
        {
            *duty_cycle = MAX_DUTY_CYCLE;
        }
    }
}

最后，需要在主函数中调用SPWM函数，生成三相SPWM波形：

float sine_table[SAMPLE_COUNTS];
float sine_table_index = 0;
float duty_cycle = 0;

for(int i = 0; i < SAMPLE_COUNTS; i++)
{
    sine_table[i] = sin(TWO_PI*i/SAMPLE_COUNTS);
}

while(1)
{
    SPWM(0, 3.3, PWM_FREQUENCY, sine_table, &sine_table_index, &duty_cycle);
    EPwm1Regs.CMPA.half.CMPA = duty_cycle*PWM_PERIOD_COUNTS;
    EPwm2Regs.CMPA.half.CMPA = duty_cycle*PWM_PERIOD_COUNTS;
    EPwm3Regs.CMPA.half.CMPA = duty_cycle*PWM_PERIOD_COUNTS;
}

上述代码中，通过调用SPWM函数生成三相SPWM波形，并将其写入EPwm1Regs、EPwm2Regs和EPwm3Regs寄存器中，以输出到三相驱动器中。