TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
        TIM_OCInitTypeDef  TIM_OCInitStructure;
    TIM_BDTRInitTypeDef TIM_BDTRInitStructure ;
   
        /* PWM信号电平跳变值 */
        u16 CCR1_Val = hBuffCH1[3];   
        u16 CCR4_Val = hBuffCH4[3];

  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);  

  
  /* Time base configuration */                 
  TIM_TimeBaseStructure.TIM_Period = 999;       //当定时器从0计数到9999，即为1000次，为一个定时周期
  TIM_TimeBaseStructure.TIM_Prescaler = 71;            //设置预分频：不预分频，即为72MHz
  TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1 ;        //设置时钟分频系数：不分频
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_CenterAligned3;  //上顶点与下低点  触发比较中断标志位
  TIM_TimeBaseStructure.TIM_RepetitionCounter = 1 ;
  
  TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);

  /* PWM1 Mode configuration: Channel1 */
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;            
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable ;
  TIM_OCInitStructure.TIM_Pulse = CCR1_Val;           //设置跳变值，当计数器计数到这个值时，电平发生跳变
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;  
  TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_Low ;
  TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset ;
  TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;
  TIM_OC1Init(TIM1, &TIM_OCInitStructure);         //使能通道1
  
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;            //配置为PWM模式1
  TIM_OCInitStructure.TIM_Pulse = 400;        //设置通道4的电平跳变值，输出另外一个占空比的PWM
  TIM_OC2Init(TIM1, &TIM_OCInitStructure);        //使能通道4

  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;            //配置为PWM模式1
  TIM_OCInitStructure.TIM_Pulse = 200;        //设置通道4的电平跳变值，输出另外一个占空比的PWM
  TIM_OC3Init(TIM1, &TIM_OCInitStructure);        //使能通道4
  
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;            //配置为PWM模式1
  TIM_OCInitStructure.TIM_Pulse = CCR4_Val;        //设置通道4的电平跳变值，输出另外一个占空比的PWM
  TIM_OC4Init(TIM1, &TIM_OCInitStructure);        //使能通道4

  TIM_OC1PreloadConfig(TIM1, TIM_OCPreload_Disable);
  TIM_OC4PreloadConfig(TIM1, TIM_OCPreload_Disable);

  /* Automatic Output enable, Break, dead time and lock configuration*/
  TIM_BDTRInitStructure.TIM_OSSRState = TIM_OSSRState_Disable;
  TIM_BDTRInitStructure.TIM_OSSIState = TIM_OSSIState_Disable;
  TIM_BDTRInitStructure.TIM_LOCKLevel = TIM_LOCKLevel_OFF;
  TIM_BDTRInitStructure.TIM_DeadTime = 20;
  TIM_BDTRInitStructure.TIM_Break = TIM_Break_Disable;
  TIM_BDTRInitStructure.TIM_BreakPolarity = TIM_BreakPolarity_High;
  TIM_BDTRInitStructure.TIM_AutomaticOutput = TIM_AutomaticOutput_Enable;
  TIM_BDTRConfig(TIM1, &TIM_BDTRInitStructure);

  TIM_ITConfig(TIM1,TIM_IT_Update,ENABLE);
     PWMNVIC_Init();     
}

void PWMNVIC_Init(void)
{
    NVIC_InitTypeDef    NVIC_InitStructure ;
    NVIC_InitStructure.NVIC_IRQChannel= TIM1_UP_IRQn;                //更新中断
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority= 1;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority= 2;
    NVIC_InitStructure.NVIC_IRQChannelCmd= ENABLE;
    NVIC_Init( &NVIC_InitStructure );
}

it.c函数
void TIM1_UP_IRQHandler(void)
{
    if(TIM_GetFlagStatus(TIM1, TIM_FLAG_Update) == SET)
    {               
        TIM_ClearFlag(TIM1,TIM_FLAG_Update);
    }
}

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我想实现的是PWM计数器在底部的时候触发一中断，实际是顶部触发一次中断，底部触发一次中断，即更新就触发一次中断。我设置了TIM_TimeBaseStructure.TIM_RepetitionCounter = 1，可能不只是这个问题，所以不懂，请教下