TMS320F28335: 关于死区时间设置

ke Lan

Part Number: TMS320F28335

您好，在设置EPWM死区模块时，用示波器观察输出EPWM波形，发现如下现象。EPWM1A经过死区模块，但是不翻转，示波器观察的是正常波形。但其他条件不变，EPWM1经过死区模块，经过翻转，即配置DBCTL[POLSEL]模块，用示波器观察输出波形，发现EPWM1已经翻转，但翻转前有个短波，且为高电平，请问这一现象怎么解释。

1 年多前

0 Yale Li 李耀先 1 年多前

TI__Guru 65745 points

方便发一下配置代码和波形吗？

0 ke Lan 1 年多前回复 Yale Li 李耀先

Prodigy 140 points

好的，EPWM代码如下：死区时间为0，频率为100khz.EPWM1和EPWM2配置一样，波形如链接所示，以EPWM1A的上升沿为触发，EPWM1B和EPWM2B在程序中设置了翻转，可以看到出发前有两个短波，而且EPWM1B比EPWM2B短波时间要长。

void Init_epwm1(void)
{

    EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Count up-down
    EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1; 
    EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1; 
    EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Enable phase loading
    EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW; // TBPRD is loaded from its shadow register
    
    EPwm1Regs.TBPRD = EPWM_PRD; // Set timer period (100kHz)
    EPwm1Regs.TBPHS.half.TBPHS = 0x0000; // Phase is 0
    EPwm1Regs.TBCTR = 0x0000; // Clear counter
    EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_CTR_ZERO; // 同步信号输出选择TBCTR=0
    EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; // CMPA Shadow mode
    EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // Load on CTR = 0
    EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; // CMPA Shadow mode
    EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // Load on CTR = 0
    
    EPwm1Regs.CMPA.half.CMPA = 2*D* EPWM_PRD; // Initial duty
    
    EPwm1Regs.AQCTLA.bit.CAU = AQ_CLEAR; // TBCTR = CMPA on Down Count：Clear
    EPwm1Regs.AQCTLA.bit.CAD = AQ_NO_ACTION; // TBCTR = CMPA on Up Count：NO ACTION
    EPwm1Regs.AQCTLA.bit.ZRO = AQ_SET; // TBCTR = 0 on Up Count：Set
    
    EPwm1Regs.AQCTLB.bit.CAU = AQ_NO_ACTION;
    EPwm1Regs.AQCTLB.bit.CAD = AQ_CLEAR;
    EPwm1Regs.AQCTLB.bit.ZRO = AQ_SET;
    
    EPwm1Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE; //0x3 MODE2 AHC high level delay (AHC)死区双边使能
    EPwm1Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC; //0x2 A不反转，B反转
    EPwm1Regs.DBCTL.bit.IN_MODE = DBA_RED_DBB_FED;
    
    EPwm1Regs.DBRED = EPWM1_DBRED; 
    EPwm1Regs.DBFED = EPWM1_DBFED; 
}

void Init_epwm2(void)
{


    EPwm2Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Count up-down
    EPwm2Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1; 
    EPwm2Regs.TBCTL.bit.CLKDIV = TB_DIV1; 
    EPwm2Regs.TBCTL.bit.PHSEN = TB_ENABLE; // Enable phase loading
    EPwm2Regs.TBCTL.bit.PRDLD = TB_SHADOW; // TBPRD is loaded from its shadow register
    
    EPwm2Regs.TBPRD = EPWM_PRD;
    
    EPwm2Regs.TBPHS.half.TBPHS = 0;
    EPwm2Regs.TBCTR = 0x0000; // Clear counter
    EPwm2Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; 
    
    EPwm2Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW; // CMPA Shadow mode
    EPwm2Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // Load on CTR = 0
    EPwm2Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW; // CMPA Shadow mode
    EPwm2Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // Load on CTR = 0
    
    
    EPwm2Regs.CMPA.half.CMPA = 2*D* EPWM_PRD; // Initial duty
    EPwm2Regs.AQCTLA.bit.CAU = AQ_CLEAR; // TBCTR = CMPA on Down Count：Clear
    EPwm2Regs.AQCTLA.bit.CAD = AQ_NO_ACTION; // TBCTR = CMPA on Up Count：NO ACTION
    EPwm2Regs.AQCTLA.bit.ZRO = AQ_SET; // TBCTR = 0 on Up Count：Set
    
    EPwm2Regs.AQCTLB.bit.CAU = AQ_NO_ACTION;
    EPwm2Regs.AQCTLB.bit.CAD = AQ_CLEAR;
    EPwm2Regs.AQCTLB.bit.ZRO = AQ_SET;
    
    EPwm2Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE; //0x3 MODE2 AHC high level delay (AHC)死区双边使能
    EPwm2Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC; //0x2 A不反转，B反转
    EPwm2Regs.DBCTL.bit.IN_MODE = DBA_RED_DBB_FED;
    
    EPwm2Regs.DBRED = EPWM2_DBRED; 
    EPwm2Regs.DBFED = EPWM2_DBFED; 

}