以下代码是在HC32F460初始化定时器A生成三路PWM的代码，TMRA_IN3PWM_CH不能输出PWM，分析一下为什么

#include "HC32F460.h"
#include "hc32f4a0_utility.h"

void PWM_Init(void)
{
    stc_tmra_init_t stcTmraInit;
    stc_tmra_pwm_init_t stcTmraPwmInit;

    DDL_ZERO_STRUCT(stcTmraInit);
    DDL_ZERO_STRUCT(stcTmraPwmInit);

    Sysctrl_SetPeripheralGate(SysctrlPeripheralTmrA, TRUE);

    stcTmraInit.u16ClockDiv = TMRA_CLKDIV_DIV1;
    stcTmraInit.u16CountMode = TMRA_MD_SAWTOOTH;
    stcTmraInit.u16CountDir = TMRA_DIR_UP;
    stcTmraInit.u16PeriodValue = 20000U;
    TMRA_Init(TMRA_UNIT, &stcTmraInit);

    stcTmraPwmInit.u32PwmCh = TMRA_PWM_U | TMRA_PWM_V | TMRA_PWM_W;
    stcTmraPwmInit.u16PwmMode = TMRA_PWM_MD_1;
    stcTmraPwmInit.u32PwmState = TMRA_PWM_STATE_ENABLE;
    stcTmraPwmInit.u16PwmDtEn = TMRA_PWM_DT_EN_INVALID;
    stcTmraPwmInit.u16PwmDeadTime = 0U;
    stcTmraPwmInit.u32PwmPortOutputMask = TMRA_PWM_OUT_MASK_CH345;
    stcTmraPwmInit.u16PwmIrqMask = TMRA_PWM_IRQ_MASK_CH345;
    TMRA_PWM_Init(TMRA_UNIT, TMRA_PWM_CH_UVW, &stcTmraPwmInit);

    TMRA_PWM_StructInit(&stcTmraPwmInit);
    stcTmraPwmInit.u32PwmCh = TMRA_PWM_U | TMRA_PWM_V | TMRA_PWM_W;
    stcTmraPwmInit.u16PwmMode = TMRA_PWM_MD_1;
    stcTmraPwmInit.u32PwmState = TMRA_PWM_STATE_ENABLE;
    stcTmraPwmInit.u16PwmDtEn = TMRA_PWM_DT_EN_INVALID;
    stcTmraPwmInit.u16PwmDeadTime = 0U;
    stcTmraPwmInit.u32PwmPortOutputMask = TMRA_PWM_OUT_MASK_CH345;
    stcTmraPwmInit.u16PwmIrqMask = TMRA_PWM_IRQ_MASK_CH345;
    TMRA_PWM_Init(TMRA_UNIT, TMRA_PWM_CH_UVW, &stcTmraPwmInit);

    TMRA_PWM_StructInit(&stcTmraPwmInit);
    stcTmraPwmInit.u32PwmCh = TMRA_PWM_U | TMRA_PWM_V | TMRA_PWM_W;
    stcTmraPwmInit.u16PwmMode = TMRA_PWM_MD_1;
    stcTmraPwmInit.u32PwmState = TMRA_PWM_STATE_ENABLE;
    stcTmraPwmInit.u16PwmDtEn = TMRA_PWM_DT_EN_INVALID;
    stcTmraPwmInit.u16PwmDeadTime = 0U;
    stcTmraPwmInit.u32PwmPortOutputMask = TMRA_PWM_OUT_MASK_CH345;
    stcTmraPwmInit.u16PwmIrqMask = TMRA_PWM_IRQ_MASK_CH345;
    TMRA_PWM_Init(TMRA_UNIT, TMRA_PWM_CH_UVW, &stcTmraPwmInit);
}

根据代码中的注释，这段代码初始化了定时器A，并使其生成三路PWM信号。但是，其中包括的 `TMRA_IN3PWM_CH` 实际上并不是一个 PWM 通道，它只是一个输入捕获通道。因此，这个通道不能用于生成 PWM 信号。

如果需要使用三路 PWM 信号，可以将 `TMRA_IN3PWM_CH` 改为 `TMRA_PWM_CH_V`，并在后面的函数调用中对应修改。