关于EPWM配置的问题：
在对PWM的相位进行同步时，要基于同步信号来进行同步，但我实在是不理解通过设置TBCTL.bit.SYNCOSEL这一位是如何影响PWM的相位的。
下面是我目前正在看的例程，可不可以通过波形的方式解释一下下面例程中标红代码的具体应用。
非常感谢。
例：
(*ePWM[n]).TBCTL.bit.PRDLD = TB_IMMEDIATE; // Set Immediate load
(*ePWM[n]).TBPRD = period;
(*ePWM[n]).TBPHS.half.TBPHS = 0;
(*ePWM[n]).TBCTR = 0; //时基寄存器清零
(*ePWM[n]).TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN;
(*ePWM[n]).TBCTL.bit.PHSEN = TB_DISABLE;
(*ePWM[n]).TBCTL.bit.SYNCOSEL = TB_CTR_CMPB; // Used to sync EPWM(n+1) "down-stream"
(*ePWM[n]).TBCTL.bit.HSPCLKDIV = TB_DIV1;
(*ePWM[n]).TBCTL.bit.CLKDIV = TB_DIV1;
// Counter compare submodule registers
(*ePWM[n]).CMPCTL.bit.SHDWAMODE = CC_IMMEDIATE;
(*ePWM[n]).CMPCTL.bit.SHDWBMODE = CC_IMMEDIATE;
(*ePWM[n]).CMPA.half.CMPA = period-68;
(*ePWM[n]).CMPB = period;
// Action Qualifier SubModule Registers
(*ePWM[n]).AQCTLA.bit.ZRO = AQ_SET;
(*ePWM[n]).AQCTLA.bit.PRD = AQ_CLEAR;
// DeadBand Control Register
(*ePWM[n]).DBCTL.bit.OUT_MODE = DB_FULL_ENABLE;
(*ePWM[n]).DBCTL.bit.POLSEL = DB_ACTV_HIC; // Active Hi Complimentary
(*ePWM[n]).DBRED = 20; // Initial value
(*ePWM[n]).DBFED = 20; // Initial value
// ePWM(n+1) init. EPWM(n+1) is a slave
//Time Base SubModule Register
(*ePWM[n+1]).TBCTL.bit.PRDLD = TB_SHADOW;
(*ePWM[n+1]).TBPRD = period-1;
(*ePWM[n+1]).TBPHS.half.TBPHS = 0;
(*ePWM[n+1]).TBCTR = 0;
(*ePWM[n+1]).TBCTL.bit.CTRMODE = TB_COUNT_UP;
(*ePWM[n+1]).TBCTL.bit.PHSEN = TB_ENABLE;
(*ePWM[n+1]).TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // Sync "flow through" mode
(*ePWM[n+1]).TBCTL.bit.HSPCLKDIV = TB_DIV1;
(*ePWM[n+1]).TBCTL.bit.CLKDIV = TB_DIV1;
// Counter compare submodule registers
(*ePWM[n+1]).CMPA.half.CMPA = period + 10; // Initial value
(*ePWM[n+1]).CMPB = 20; // Initial value
(*ePWM[n+1]).CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
(*ePWM[n+1]).CMPCTL.bit.SHDWAMODE = CC_SHADOW;
(*ePWM[n+1]).CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
(*ePWM[n+1]).CMPCTL.bit.SHDWBMODE = CC_SHADOW;
// Action Qualifier SubModule Registers
(*ePWM[n+1]).AQCTLA.bit.CAU = AQ_SET;
(*ePWM[n+1]).AQCTLA.bit.CBU = AQ_CLEAR;
(*ePWM[n+1]).AQCTLA.bit.ZRO = AQ_CLEAR;
(*ePWM[n+1]).AQCTLA.bit.PRD = AQ_CLEAR;
(*ePWM[n+1]).AQCTLB.bit.CBU = AQ_SET;
(*ePWM[n+1]).AQCTLB.bit.CAU = AQ_CLEAR;
(*ePWM[n+1]).AQCTLB.bit.ZRO = AQ_CLEAR;
(*ePWM[n+1]).AQCTLB.bit.PRD = AQ_CLEAR;
