PWM信号如何正确调制为正弦波形。

发表于 2024-8-16 13:37

将PWM信号正确调制为正弦波形需要使用正弦脉宽调制（SPWM）技术。SPWM通过调整PWM信号的占空比，使其在一个周期内近似为正弦波形。以下是详细的步骤和示例代码，展示如何在STM32上实现SPWM。

1. 正弦查找表
首先，创建一个正弦波查找表，用于生成SPWM信号。查找表中的值表示正弦波在一个周期内的不同时刻对应的幅值。

c
#define SINE_TABLE_SIZE 256  // 查找表大小

// 正弦查找表
const uint16_t sineTable[SINE_TABLE_SIZE] = {
2048, 2098, 2148, 2198, 2248, 2298, 2348, 2397, 2447, 2496, 2545, 2594, 2642, 2691, 2738, 2786,
2833, 2880, 2926, 2972, 3018, 3063, 3108, 3152, 3195, 3238, 3281, 3323, 3364, 3405, 3445, 3484,
3523, 3561, 3598, 3635, 3671, 3706, 3740, 3773, 3806, 3837, 3868, 3898, 3927, 3955, 3982, 4008,
4033, 4057, 4080, 4102, 4123, 4143, 4161, 4179, 4195, 4210, 4224, 4237, 4249, 4259, 4269, 4277,
4283, 4289, 4293, 4296, 4298, 4299, 4299, 4298, 4296, 4293, 4289, 4283, 4277, 4269, 4259, 4249,
4237, 4224, 4210, 4195, 4179, 4161, 4143, 4123, 4102, 4080, 4057, 4033, 4008, 3982, 3955, 3927,
3898, 3868, 3837, 3806, 3773, 3740, 3706, 3671, 3635, 3598, 3561, 3523, 3484, 3445, 3405, 3364,
3323, 3281, 3238, 3195, 3152, 3108, 3063, 3018, 2972, 2926, 2880, 2833, 2786, 2738, 2691, 2642,
2594, 2545, 2496, 2447, 2397, 2348, 2298, 2248, 2198, 2148, 2098, 2048, 1998, 1948, 1898, 1848,
1798, 1749, 1700, 1651, 1602, 1553, 1505, 1456, 1408, 1361, 1313, 1266, 1219, 1173, 1127, 1082,
1037,  992,  948,  905,  862,  819,  777,  736,  695,  654,  614,  575,  536,  498,  461,  424,
   388,  353,  319,  285,  252,  219,  188,  157,  127, 98, 70, 43, 16, 1, 0, 0,
   0, 0, 0, 1, 16, 43, 70, 98,  127,  157,  188,  219,  252,  285,  319,  353,
   388,  424,  461,  498,  536,  575,  614,  654,  695,  736,  777,  819,  862,  905,  948,  992,
1037, 1082, 1127, 1173, 1219, 1266, 1313, 1361, 1408, 1456, 1505, 1553, 1602, 1651, 1700, 1749,
1798, 1848, 1898, 1948, 1998, 2048
};

发表于 2024-8-16 13:38

定时器配置
使用STM32的定时器模块生成PWM信号。

c
复制代码
void PWM_Init(void)
{
TIM_HandleTypeDef htim1;
TIM_OC_InitTypeDef sConfigOC;

__HAL_RCC_TIM1_CLK_ENABLE();

htim1.Instance = TIM1;
htim1.Init.Prescaler = 0;
htim1.Init.CounterMode = TIM_COUNTERMODE_UP;
htim1.Init.Period = 4095; // 对应12位精度的PWM
htim1.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim1.Init.RepetitionCounter = 0;
HAL_TIM_PWM_Init(&htim1);

sConfigOC.OCMode = TIM_OCMODE_PWM1;
sConfigOC.Pulse = 0;
sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
sConfigOC.OCNPolarity = TIM_OCNPOLARITY_HIGH;
sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
sConfigOC.OCIdleState = TIM_OCIDLESTATE_RESET;
sConfigOC.OCNIdleState = TIM_OCNIDLESTATE_RESET;
HAL_TIM_PWM_ConfigChannel(&htim1, &sConfigOC, TIM_CHANNEL_1);

HAL_TIM_PWM_Start(&htim1, TIM_CHANNEL_1);
}

发表于 2024-8-16 13:39

更新PWM占空比
使用查找表更新PWM占空比，实现SPWM调制。

c
void UpdatePWM(void)
{
static uint16_t step = 0;

// 更新PWM占空比
__HAL_TIM_SET_COMPARE(&htim1, TIM_CHANNEL_1, sineTable[step]);

// 更新步进
step++;
if (step >= SINE_TABLE_SIZE) {
step = 0;
}
}

// 主循环中定时调用UpdatePWM函数
while (1)
{
UpdatePWM();
HAL_Delay(1); // 根据需要调整延时，控制频率
}

发表于 2024-8-16 13:40

完整代码
将以上各部分组合起来，形成完整的PWM生成和正弦波调制代码。

c
#include "stm32f4xx_hal.h"

#define SINE_TABLE_SIZE 256

const uint16_t sineTable[SINE_TABLE_SIZE] = {
// 正弦查找表值
2048, 2098, 2148, 2198, 2248, 2298, 2348, 2397, 2447, 2496, 2545, 2594, 2642, 2691, 2738, 2786,
2833, 2880, 2926, 2972, 3018, 3063, 3108, 3152, 3195, 3238, 3281, 3323, 3364, 3405, 3445, 3484,
3523, 3561, 3598, 3635, 3671, 3706, 3740, 3773, 3806, 3837, 3868, 3898, 3927, 3955, 3982, 4008,
4033, 4057, 4080, 4102, 4123, 4143, 4161, 4179, 4195, 4210, 4224, 4237, 4249, 4259, 4269, 4277,
4283, 4289, 4293, 4296, 4298, 4299, 4299, 4298, 4296, 4293, 4289, 4283, 4277, 4269, 4259, 4249,
4237, 4224, 4210, 4195, 4179, 4161, 4143, 4123, 4102, 4080, 4057,

发表于 2024-8-17 23:06

查表法吗

发表于 2024-8-28 12:07

为了实现SPWM，首先需要生成一个正弦波查找表。这个查找表存储正弦波在一个周期内的不同时刻的幅值，用于调整PWM信号的占空比。

[STM32F4] PWM信号如何正确调制为正弦波形。

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