基于单片机的直流电机闭环调速系统的设计.doc

毕业设计说明书
基于单片机的直流电机闭环调速
系统的设计
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2012 年 6 月
基于单片机的直流电机闭环调速系统的设计
摘要:在运动控制系统中,电机转速控制占有至关重要的作用,其控制算法和手段有很多,模拟PID控制是最早发展起来的控制策略之一,长期以来形成了典型的结构,并且参数整定方便,能够满足一般控制的要求,但由于在模拟PID控制系统中,参数一旦整定好后,在整个控制过程中都是固定不变的,而在实际中,由于现场的系统参数、温度等条件发生变化,使系统很难达到最佳的控制效果,因此采用模拟PID控制器难以获得满意的控制效果。随着计算机技术与智能控制理论的发展,数字PID技术渐渐发展起来,它不仅能够实现模拟PID所完成的控制任务,而且具备控制算法灵活、可靠性高等优点,应用面越来越广。
本设计以上面提到的数字PID为基本控制算法,以AT89S51单片机为控制核心,产生占空比受数字PID算法控制的PWM脉冲实现对直流电机转速的控制。同时利用霍尔传感器将电机速度转换成脉冲频率反馈到单片机中,实现转速闭环控制,达到转速检测目的。在系统中采用LCD1602显示器作为显示部件,通过5个按键来实现正反转和加减速控制,启动后可以通过显示部件了解电机当前的转速。电机驱动部分采用的是专门的驱动芯片来实现正反转控制。
关键词:数字PID,PWM脉冲,直流电机
DC motor closed-loop speed control system based on single-chip design
Abstract:In the motion control system, the control of electro motor's rotate speed is of great importance, there are a lot of speed control arithmetics and methods , the analog PID control is one of the earliest developed control policies which has formed typical structure, its parametric setting is convenient and it's easy to meet normal control's demand, but as the whole control process is fixed once the parameter has been set while practically the changes of those conditions like the system parameters and temperature of the environment prohibit the system from reaching its best control effect, so the analog PID controller barely has satisfied effect. With the development puter technology and intelligent control theory , the digital PID technology is thriving which can achieve the analog PID's control tasks and consists of many advantages like flexible control arithmetics and high reliability, it is widely used now.
This design is based on the digital PID mentioned above as basic control arithmetic and AT89S51 SCM as control core, the system produces PWM impulse whose duty ratio is controlled by digital PID arithmetic to make sure the running of direct current machine's rotate speed. At the same time using Holzer sensors will be converted into pulse frequency motor speed feedback to th