STM32· PWM启动不了

#include "STM32f10x_lib.h"
#include "stdio.h"
#include"delay.h"
#include"sys.h"
void RCC_Configuration(void);
void GPIO_Configuration(void);
void TIM_Configuration(void);
void PWM_Enable(void);  //启动PWM
void PWM_DISABLE(void);   //失能PWM
unsigned int Light_level;//调脉宽
vu16 PWM_level[5]={500,25000,35000,45000,55000};//PWM脉宽
int main(void)
{ //初始化
   RCC_Configuration();
   GPIO_Configuration();
   TIM_Configuration();
   Light_level=PWM_level[4];
   PWM_DISABLE();
   PWM_Enable();
   while(1)
    {
   
    }
}
void RCC_Configuration(void)
{  ErrorStatus HSEStartUpStatus;
   RCC_DeInit();
   RCC_HSEConfig(RCC_HSE_ON);
   HSEStartUpStatus=RCC_WaitForHSEStartUp();
   if(HSEStartUpStatus==SUCCESS)
   {
   RCC_HCLKConfig(RCC_SYSCLK_Div1);
   RCC_HCLKConfig(RCC_HCLK_Div1);
   RCC_HCLKConfig(RCC_HCLK_Div2);
   FLASH_SetLatency(FLASH_Latency_2);
   FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
   RCC_PLLConfig(RCC_PLLSource_HSE_Div1,RCC_PLLMul_9);
   RCC_PLLCmd(ENABLE);
   while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY)==RESET);
   RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
   while(RCC_GetSYSCLKSource()!=0x08);
   }
   RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE) ;
   RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB|RCC_APB2Periph_GPIOA|RCC_APB2Periph_GPIOD,ENABLE);
}
void TIM_Configuration(void)//PWM
{
   TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
   TIM_OCInitTypeDef TIM_OCInitStructure;
   TIM_TimeBaseStructure.TIM_Period=60000;
   TIM_TimeBaseStructure.TIM_Prescaler=0;
   TIM_TimeBaseStructure.TIM_ClockDivision=0;
   TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up;
   TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStructure);
   TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1;
   TIM_OCInitStructure.TIM_OutputState=TIM_OutputState_Enable;
   TIM_OCInitStructure.TIM_OCPolarity=TIM_OCPolarity_High;
  TIM_OCInitStructure.TIM_Pulse=Light_level;//设置脉宽
   TIM_OC3Init(TIM3,&TIM_OCInitStructure);
}
void PWM_Enable(void)
{
   TIM_OCInitTypeDef TIM_OCInitStructure;
   TIM_OCInitStructure.TIM_Pulse=Light_level;//设置脉宽
   TIM_OC3Init(TIM3,&TIM_OCInitStructure);
   TIM_OC3PreloadConfig(TIM3,TIM_OCPreload_Enable);
   TIM_ARRPreloadConfig(TIM3,ENABLE);
   TIM_Cmd(TIM3,ENABLE);
}
void PWM_DISABLE(void)
{
   TIM_OC3PreloadConfig(TIM3,TIM_OCPreload_Disable);
   TIM_ARRPreloadConfig(TIM3,DISABLE);
   TIM_Cmd(TIM3,DISABLE);   
}
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
GPIO_InitStructure.GPIO_Pin=GPIO_Pin_0;
    GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_Out_PP;
GPIO_Init(GPIOB,&GPIO_InitStructure);
}
我想用STM32的TIM3CH3（PB0）产生PWM，但是PB0所连接的LED一直没亮，不管怎么调TIM_OCInitStructure.TIM_Pulse和TIM_TimeBaseStructure.TIM_Period，求解答！！