（字数：20003 页数：56）

摘 要
由于以微处理器为核心的数字控制系统硬件电路的标准化程度高，制作成本低，且不受器件温度漂移的影响。其控制软件能够进行逻辑判断和复杂运算。所以微机数字控制系统在各个方面的性能都远远优于模拟控制系统且应用越来越广泛。
本文介绍的是用一台1.1kW的直流电动机，8051单片机构成的数字化直流调速系统。特点是用单片机取代模拟触发器、电流调节器、速度调节器及逻辑切换等硬件设备。采用高分辨率数字触发器代替了模拟的“线形锯齿波”移相触发器，由数字逻辑切换单元控制的电子开关自动选择触发正桥还是反桥的晶闸管工作桥，实现对三相全控桥电路的准确触发。本数字化直流调速系统实现了电流和转速双闭环的恒速调节，并具有结构简单，控制精度高，成本低，易推广等特点，而且各项性能指标优于模拟直流调速系统，从而能够实际的应用到生产生活中，满足现代化生产的需要。

关键词：单片机,双闭环,直流调速系统,数字方式

ABSTRACT
Since the hardware circuit of digital control system centered by microprocessor possesses the advantages that it has higher standardization and lower cost, and it doesn’t be influenced by temperature drift of devices. In every aspects the function of digital control system has exceeded analog control system and is being used widely.
Here is a digital DC speed control system composed by 1.1kW DC motor and 8051 single-chip computer, which has the characteristic that the analog trigger, current regulator, rotation regulator, logical handoff and other devices were replaced by single-chip computer. The result of real time control indicates that the digital DC speed control system realized the constant speed adjustability of the double closed-loop of electric current and rotate speed. This system also has the specialties such as simple structure, high control accuracy, low cost and easiness to be spread. In addition, its entire performance index is better than analog DC speed control system. As a result, the digital DC speed control system could be applied into production and ordinary life to satisfy the needs of modern manufacture.

Keywords: Single-chip computer；Double closed-loop ；DC speed control system；Digital model