（1）原理介绍

        F280049C的PWM模块功能强大，可以比较容易的实现移相控制。 本节主要向大家讲述用DSP如何编程实现移相控制，如下图所示为移相全桥变换器的移相控制示意图，其中EPWM1A和EPWM1B为占空比50%的互补信号，EPWM2A和EPWM2B也为占空比50%的互补信号。通过控制EPWM1A和EPWM2B的移相角来实现移相控制。          如上图标注所示，控制上以PWM1的计数时基为基准信号，在PWM1的计数器为零（宏：EPWM_SYNC_OUT_PULSE_ON_COUNTER_ZERO）时PWM1发出同步脉冲SyncOut，同时配置PWM2的同步信号来源为Syncln（宏：EPWM_SYNC_OUT_PULSE_ON_EPWMxSYNCIN）。相关的宏定义如下所示： typedef enum { //! sync pulse is generated by software EPWM_SYNC_OUT_PULSE_ON_SOFTWARE = 0, //! sync pulse is passed from EPWMxSYNCIN EPWM_SYNC_OUT_PULSE_ON_EPWMxSYNCIN = 0, //! sync pulse is generated when time base counter equals zero EPWM_SYNC_OUT_PULSE_ON_COUNTER_ZERO = 1, //! sync pulse is generated when time base counter equals compare B value. EPWM_SYNC_OUT_PULSE_ON_COUNTER_COMPARE_B = 2, //! sync pulse is disabled EPWM_SYNC_OUT_PULSE_DISABLED = 4, //! sync pulse is generated when time base counter equals compare D value. EPWM_SYNC_OUT_PULSE_ON_COUNTER_COMPARE_C = 5, //! sync pulse is disabled. EPWM_SYNC_OUT_PULSE_ON_COUNTER_COMPARE_D = 6 }EPWM_SyncOutPulseMode;           当PWM1的时基计数到零数发出同步脉冲，此时，PWM2接收到同步脉冲后将相位寄存器TBPHS中的值加载到时基计数器TBCTR中。也就是说，当PWM1从零开始计数时，PWM2此时从TBPHS寄存器中的值开始计数。因此，PWM1和PWM2实现了移相，改变TBPHS寄存器中的值可以改变移相控制的移相角。

（2）相关寄存器配置

如上图所示，PWM1只需要配置其何时发出同步脉冲即可，相关配置如下所示： EPWM_setSyncOutPulseMode(EPWM1_BASE,EPWM_SYNC_OUT_PULSE_ON_COUNTER_ZERO); //计数到零时发出同步脉冲 PWM2需要配置其同步脉冲输入源和相位寄存器TBPHS的值，同时还需要使能相位寄存器的加载（图中的En，寄存器TBCTL中的PHSEN位），相关配置代码如下： EPWM_enablePhaseShiftLoad(EPWM2_BASE); //使能相位寄存器 EPWM_setSyncOutPulseMode(EPWM2_BASE,EPWM_SYNC_OUT_PULSE_ON_EPWMxSYNCIN); //计数到零时发出同步脉冲 EPWM_setPhaseShift(EPWM2_BASE,250); //设置初始移相值

（3）PWM1和PWM2的配置 

        PWM1和PWM2的完整配置程序如下所示，其中包含了基本PWM输出的配置、死区时间的配置和移相控制的配置，每句程序后边都有详细的注释，方便大家阅读理解。要想实现PWM的输出，还需要配置与PWM相关的GPIO引脚，限于篇幅，在此不再列出，需要的话大家可以下载完整的实验工程（下载链接见文章末尾）。 void ePWM1_Configuration(void) { EPWM_setClockPrescaler(EPWM1_BASE, EPWM_CLOCK_DIVIDER_1, EPWM_HSCLOCK_DIVIDER_1); //ePWM 时钟为100MHZ EPWM_setTimeBaseCounterMode(EPWM1_BASE,EPWM_COUNTER_MODE_UP); //设置计数模式（增计数） EPWM_setTimeBaseCounter(EPWM1_BASE,0); //计数初始值设置 EPWM_setTimeBasePeriod(EPWM1_BASE,1000); //计数周期 fs=100kHz EPWM_setPeriodLoadMode(EPWM1_BASE,EPWM_PERIOD_SHADOW_LOAD); //周期加载模式 EPWM_setCounterCompareShadowLoadMode(EPWM1_BASE, EPWM_COUNTER_COMPARE_A, EPWM_COMP_LOAD_ON_CNTR_ZERO_PERIOD);//比较值加载模式 EPWM_setCounterCompareValue(EPWM1_BASE,EPWM_COUNTER_COMPARE_A,500); //设定比较值 EPWM_setCounterCompareValue(EPWM1_BASE,EPWM_COUNTER_COMPARE_B,500); EPWM_setActionQualifierAction(EPWM1_BASE, EPWM_AQ_OUTPUT_A, EPWM_AQ_OUTPUT_LOW, EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPA); //ePWMA的 EPWM_setActionQualifierAction(EPWM1_BASE, EPWM_AQ_OUTPUT_A, EPWM_AQ_OUTPUT_HIGH, EPWM_AQ_OUTPUT_ON_TIMEBASE_PERIOD); EPWM_setSyncOutPulseMode(EPWM1_BASE,EPWM_SYNC_OUT_PULSE_ON_COUNTER_ZERO); //计数到零时发出同步脉冲 EPWM_setRisingEdgeDeadBandDelayInput(EPWM1_BASE,EPWM_DB_INPUT_EPWMA); EPWM_setFallingEdgeDeadBandDelayInput(EPWM1_BASE,EPWM_DB_INPUT_EPWMA); //配置死区输入模式 EPWM_setDeadBandDelayPolarity(EPWM1_BASE,EPWM_DB_RED,EPWM_DB_POLARITY_ACTIVE_HIGH); EPWM_setDeadBandDelayPolarity(EPWM1_BASE,EPWM_DB_FED,EPWM_DB_POLARITY_ACTIVE_LOW);//配置极性 EPWM_setDeadBandDelayMode(EPWM1_BASE,EPWM_DB_RED,true); EPWM_setDeadBandDelayMode(EPWM1_BASE,EPWM_DB_FED,true); //配置输出模式 EPWM_setDeadBandOutputSwapMode(EPWM1_BASE,EPWM_DB_OUTPUT_A,false); EPWM_setDeadBandOutputSwapMode(EPWM1_BASE,EPWM_DB_OUTPUT_B,false); //输出不交换 EPWM_setRisingEdgeDelayCount(EPWM1_BASE,0); //上升沿延时0nS EPWM_setFallingEdgeDelayCount(EPWM1_BASE,0); //下降沿延时0nS EPWM_enableADCTrigger(EPWM1_BASE,EPWM_SOC_A); EPWM_setADCTriggerSource(EPWM1_BASE,EPWM_SOC_A,EPWM_SOC_TBCTR_ZERO); EPWM_setADCTriggerEventPrescale(EPWM1_BASE,EPWM_SOC_A,1); } void ePWM2_Configuration(void) { EPWM_setClockPrescaler(EPWM2_BASE, EPWM_CLOCK_DIVIDER_1, EPWM_HSCLOCK_DIVIDER_1); //ePWM 时钟为100MHZ EPWM_setTimeBaseCounterMode(EPWM2_BASE,EPWM_COUNTER_MODE_UP); //设置计数模式（增计数） EPWM_setTimeBaseCounter(EPWM2_BASE,0); //计数初始值设置 EPWM_setTimeBasePeriod(EPWM2_BASE,1000); //计数周期 fs=100kHz EPWM_setPeriodLoadMode(EPWM2_BASE,EPWM_PERIOD_SHADOW_LOAD); //周期加载模式 EPWM_setCounterCompareShadowLoadMode(EPWM2_BASE, EPWM_COUNTER_COMPARE_A, EPWM_COMP_LOAD_ON_CNTR_ZERO_PERIOD);//比较值加载模式 EPWM_setCounterCompareValue(EPWM2_BASE,EPWM_COUNTER_COMPARE_A,500); //设定比较值 EPWM_setCounterCompareValue(EPWM2_BASE,EPWM_COUNTER_COMPARE_B,500); EPWM_setActionQualifierAction(EPWM2_BASE, EPWM_AQ_OUTPUT_A, EPWM_AQ_OUTPUT_LOW, EPWM_AQ_OUTPUT_ON_TIMEBASE_UP_CMPA); //ePWMA的 EPWM_setActionQualifierAction(EPWM2_BASE, EPWM_AQ_OUTPUT_A, EPWM_AQ_OUTPUT_HIGH, EPWM_AQ_OUTPUT_ON_TIMEBASE_PERIOD); EPWM_enablePhaseShiftLoad(EPWM2_BASE); //使能相位寄存器 EPWM_setSyncOutPulseMode(EPWM2_BASE,EPWM_SYNC_OUT_PULSE_ON_EPWMxSYNCIN); //计数到零时发出同步脉冲 EPWM_setPhaseShift(EPWM2_BASE,250); //设置初始移相值 EPWM_setRisingEdgeDeadBandDelayInput(EPWM2_BASE,EPWM_DB_INPUT_EPWMA); EPWM_setFallingEdgeDeadBandDelayInput(EPWM2_BASE,EPWM_DB_INPUT_EPWMA); //配置死区输入模式 EPWM_setDeadBandDelayPolarity(EPWM2_BASE,EPWM_DB_RED,EPWM_DB_POLARITY_ACTIVE_HIGH); EPWM_setDeadBandDelayPolarity(EPWM2_BASE,EPWM_DB_FED,EPWM_DB_POLARITY_ACTIVE_LOW);//配置极性 EPWM_setDeadBandDelayMode(EPWM2_BASE,EPWM_DB_RED,true); EPWM_setDeadBandDelayMode(EPWM2_BASE,EPWM_DB_FED,true); //配置输出模式 EPWM_setDeadBandOutputSwapMode(EPWM2_BASE,EPWM_DB_OUTPUT_A,false); EPWM_setDeadBandOutputSwapMode(EPWM2_BASE,EPWM_DB_OUTPUT_B,false); //输出不交换 EPWM_setRisingEdgeDelayCount(EPWM2_BASE,0); //上升沿延时0nS EPWM_setFallingEdgeDelayCount(EPWM2_BASE,0); //下降沿延时0nS }

（4）实验波形

设定移相角为90度，开关频率为100kHZ，占空比为50%。输出PWM1A和PWM2A的波形如下所示： F280049移相控制完整的CCS工程我已经上传到了CSDN上，需要的可自行下载哈，程序中有不懂得地方都可以给我留言哈。下载链接如下： https://download.csdn.net/download/fanxianyan1993/11110315