双极性SPWM调制

UPS电压稳压控制原理框图（以A相为例）如下：

慢环稳压算法采用增量式PI控制器，一周期计算控制量一次，三相独立控制。

误差计算error=（参考-输出有效值）；

注：输出有效值一周期更新一次，采样频率为9K。

PI算法：

A_Uk=A_Uk+(P+I)*error(k)-P*error（k-1）；0

B_Uk=B_Uk+(P+I)*error(k)-P*error（k-1）；0

C_Uk=C_Uk+(P+I)*error(k)-P*error（k-1）；0

采用双极性调制：

SPWM波形生成算法：查正弦表法（其它有对称规则采样法、不对称规则采样法、等效面积采样法，计算量相对大些）。

在程序中要保证：

比较值 = 周期/2 + (_IQ14mpy(Sin60HzTAB[当前点],A_UK<<2)*周期/2) >> 14；

因为 _IQ14(-1)< Sin60HzTAB[当前点] <_IQ14(1)；

可求得：0 < AUk_Max = BUk_Max = CUk_Max = Mk_Max < 4096。

逆变输出控制量限幅选择公式：Mk_Max*0.9=A_UK稳定值；“A_UK稳定值”是在保证UPS空载输出电压稳定在期望值后对应的A_UK值；当前有六种电压期望值:220V/230V/240V/50Hz和220V/230V/240V/60Hz；“A_UK稳定值”需要在线调试得到，最终计算出六种Mk_Max值。

本项目采用固定点数输出SPWM，逆变开关频率9kHz（实际驱动开关频率3kHz），即50Hz对应180个采样点，60Hz对应150个采样点，Sin60HzTAB[k]= _IQ14(sin(2*π*k/150))，k∈[0,149]；Sin50HzTAB[k]=_IQ14(sin(2*π*k/180))，k∈[0,179]。

正弦表：

/****************sin Table IQ14(-0.999~0.999)******************/

int32 const Sin50HzTAB[] = {

 286,  857, 1428, 1997, 2563, 3126, 3686, 4240, 4790, 5334,5872, 6402, 6924, 7438, 7943, 8438, 8923, 9397, 9860,10311,10749,11174,11585,11982,12365,12733,13085,13421,13741,14044,14330,14598,14849,15082,15296,15491,15668,15826,15964,16083,16182,16262,16322,16362,16382,16382,16362,16322,16262,16182,16083,15964,15826,15668,15491,15296,15082,14849,14598,14330,14044,13741,13421,13085,12733,12365,11982,11585,11174,10749,10311, 9860, 9397, 8923, 8438, 7943, 7438, 6924, 6402, 5872,5334, 4790, 4240, 3686, 3126, 2563, 1997, 1428,  857,  286,-286,  -857, -1428, -1997, -2563, -3126,-3686,-4240,-4790,-5334,-5871,-6402-6924-7438,-7943,-8438,-8923,-9397,-9860,-10311,-10749,-11174,-11585,-11982,-12365,-12733,-13085,-13421,-13741,-14044,-14330,-14598,-14849,-15082,-15296,-15491,-15668,-15826,-15964,-16083,-16182,-16262,-16322,-16362,-16382,-16382,-16362,-16322,-16262,-16182,-16083,-15964,-15826,-15668,-15491,-15296,-15082,-14849,-14598,-14330,-14044,-13741,-13421,-13085,-12733,-12365,-11983,-11585,-11174,-10749,-10311, -9860, -9397, -8923, -8438, -7943, -7438, -6924, -6402, -5872,-5334, -4790, -4240, -3686, -3126, -2563, -1997, -1428,  -857, -286};

PI调节：

if (2 == Sin_Counter )

{

    A_Vout_Ek = (VAref_Period - A_Vout_Aver);

    if (A_Vout_Ek > 50 ) A_Vout_Ek = 50;

    if (A_Vout_Ek < -50 ) A_Vout_Ek = -50;

    A_Uk_Temp = (Urms_Kp + Urms_Ki) * A_Vout_Ek  - Urms_Kp *  A_Vout_EK_1;

    A_Uk_Temp = A_Uk_Temp >> 16;

    A_UK = A_UK + A_Uk_Temp;

    if (A_UK < 0 )A_UK = 0;

    if (A_UK > AUk_Max )

    {

        A_UK = AUk_Max;

    }

    A_Vout_EK_1 = A_Vout_Ek;

}

计算比较值：

{

    AM = Sin_Counter;                                // AM=sin_counter

    SPWM_Temp2 = EPwm1Regs.TBPRD >> 1;           // 逆变输出波形周期计算

    SPWM_Temp1 = Sin50HzTAB[AM];                 // 查表

    SPWM_Temp3 = (_IQ14mpy( SPWM_Temp1, A_UK<<2) * SPWM_Temp2 ) >> 14;

    AM =(int)( SPWM_Temp2 + SPWM_Temp3 );

    EPwm1Regs.CMPA.half.CMPA = AM;                // EPWM1比较值更新

    EPwm2Regs.CMPA.half.CMPA = BM;                // EPWM2比较值更新

    EPwm3Regs.CMPA.half.CMPA = CM;                // EPWM3比较值更新

}