STM32高级定时器产生带死区的PWM波形，需要注意几点。
1. 同一通道的两路相反PWM波需要分别使能，如
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;
2. 除了时钟使能就PWM输出也需单独使能
TIM_Cmd（TIM1, ENABLE);
TIM_CtrlPWMOutputs(TIM1,ENABLE);