F28377D EPWM中断周期计算与实测差了一倍

以下是epwm的设置，按主频200M来计算，EPWM3B输出频率应该是50K，可是实际测出来是25K，是我设置问题还是理解出了问题，希望工程师能帮忙解决下
void InitEPwm3Example(void)
[
// Setup TBCLK
EPwm3Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP; // Count up
EPwm3Regs.TBPRD = EPWM3_tiMER_TBPRD; // Set timer period
EPwm3Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Disable phase loading
EPwm3Regs.TBPHS.bit.TBPHS = 0x0000; // Phase is 0
EPwm3Regs.TBCTR = 0x0000; // Clear counter
EPwm3Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1; // Clock ratio to SYSCLKOUT，0x00
EPwm3Regs.TBCTL.bit.CLKDIV = TB_DIV1;
// Setup shadow register load on ZERO
EPwm3Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm3Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm3Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
EPwm3Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
// Set Compare values
EPwm3Regs.CMPA.bit.CMPA = EPWM3_MIN_CMPA; // Set compare A value
EPwm3Regs.CMPB.bit.CMPB = EPWM3_MAX_CMPB; // Set Compare B value
// Set Actions
EPwm3Regs.AQCTLA.bit.CAU = AQ_SET; // Set PWM3A on event B, up count
EPwm3Regs.AQCTLA.bit.CBU = AQ_CLEAR; // Clear PWM3A on event B, up count
EPwm3Regs.AQCTLB.bit.ZRO = AQ_TOGGLE; // Toggle EPWM3B on Zero
// Interrupt where we will change the Compare Values
EPwm3Regs.ETSEL.bit.INTSEL = ET_CTR_ZERO; // Select INT on Zero event
EPwm3Regs.ETSEL.bit.INTEN = 1; // Enable INT
EPwm3Regs.ETPS.bit.INTPRD = ET_3RD; // Generate INT on 3rd event
]