> For the complete documentation index, see [llms.txt](https://libooogo.gitbook.io/esplane/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://libooogo.gitbook.io/esplane/developer-guide/12esp32+-kong-xin-bei-you-shua-dian-ji.md).

# 10 Brushed Motor Driver

## 一、 pwm控制原理

![控制电路](https://img-blog.csdnimg.cn/20191031200744442.png)

* PWM就是Pulse Width Modulation,脉冲宽度调制.
* 一般输出后面加上一个(一阶或两阶)`RC低通滤波电路`,去除纹波,将PWM信号转换成等效的直流信号. 
* 假设一个电源电压为 +5V,使用占空比 50%控制通断,那么它输出的信号就可以看成是一个+2.5V的直流信号.
* `我们使用PWM控制电机转速,正是使用PWM控制电压实现`
* 分辨率越高,波形就越精细
* 频率高可以减少频闪

![低通滤波电路对输出的影响](https://img-blog.csdnimg.cn/20191031194603829.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNTE1NDYx,size_16,color_FFFFFF,t_70)

以上图片来源:[电路/定理PWM波变直流电压](http://bbs.21ic.com/icview-1665776-1-1.html) 其他参考资料:[怎样才能将占空比变化转换成相应的电压信号](http://bbs.eeworld.com.cn/thread-414879-1-1.html)

## 二、MOS芯片参数

[SI2302DS data-sheet](https://assets.nexperia.com/documents/data-sheet/SI2302DS.pdf)

![pin](https://img-blog.csdnimg.cn/20191031201415863.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNTE1NDYx,size_16,color_FFFFFF,t_70)

![动态特性](https://img-blog.csdnimg.cn/20191031201440130.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNTE1NDYx,size_16,color_FFFFFF,t_70)

![动态特性曲线](https://img-blog.csdnimg.cn/20191031201520397.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIwNTE1NDYx,size_16,color_FFFFFF,t_70)

## 三、空心杯电机参数

| 参数项  | 参数值                           |
| ---- | ----------------------------- |
| 直径   | 7mm                           |
| 电机长度 | 16mm                          |
| 输出轴  | 0.8mm                         |
| 重量   | 5g                            |
| 额定电压 | 3.4v                          |
| 启动电压 | 0.5v                          |
| 额定电流 | 800mA                         |
| 转速   | 3V:35000-37000  5V: 50000 RPM |

## 四、esp32 pwm控制实验

实验发现使用ledc(esp32 release/3.3)模块,如果设置频率过高,会出现频率和占空比异常.以下所有图片设置的占空比均为 300 KHz,8bit分辨率,会出现频率的波动,被控制的电机肉眼比较难看出区别,这一点需要注意.要么调低频率,要么调低分辨率.数据手册上有计算公式,有空算一下作出补充

```
计算公式:
```


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