文档介绍：摘 要
在电力传动系统中，交流电动机具有一些直流电动机无法比拟的优点，如单机容量、电枢电压、额定转速、价格等方面。但由于交流电机的调速一直比较困难，所以，长期以来,交流电机只能作恒速运行,而在要求精确、灵活、连续调速的传动系统中,直流电机调速传动一直占主要地位。然而，近年来，一方面随着大功率可控电力电子元件和变频技术的迅速发展,用交流电机的调速传动系统代替直流电机调速传动系统已成为可能，另一方面，从节能的观点要求把原来作恒速运行的交流电机传动系统改为调速传动。因而，在电力传动领域里正在日益重视发展交流电机的调速传动,成为电动机调速新的发展方向。
交流调压调速系统设计思想是用改变异步电动机定子电压来实现调节电动机转速的控制系统称为调压调速系统，而电机定子电压是通过晶闸管元件组成的调压器进行控制。通过控制晶闸管的触发角，就可以对输出交流基波电压有效值进行控制,来达到调压调速的目的。
系统的总体结构主要由主回路,驱动电路,光电隔离电路，触发器,电压电流检测保护电路,STC89C51RC单片机,测速发电机等组成.
调压调速的电路简单，成本低廉、操作简单、方便，多用于对调速性能要求不高的中、小容量拖动装置中.
关键字:晶闸管；调压调速；单片机
ABSTRACT
In the power transmission system， AC motor has some DC motor can not match the advantages, such as stand—alone capacity, armature voltage， rated speed and price。 But due to the AC motor speed control has been more difficult， so for a long time, the AC motor can only for constant speed operation， and requires accurate, flexible and continuous speed control of the drive system, DC motor drive has accounted for a major position. However, in recent years, on the one hand， with the rapid development of high power controllable power electronic components and frequency conversion technology， AC motor variable speed drive system to replace the DC motor drive system has become possible， on the other hand, from the viewpoint of saving asked to original constant speed AC motor drive system change is an adjustable speed drive. So in the field of power transmission is being paid increasing attention development of AC motor variable speed drive， become the new development direction of the m
otor speed.
AC adjustable speed system design pressure is by changing the stator voltage to realize adjustment of motor speed control system for pressure regulating and speed control system， and motor stator voltage is through the thyristor tube element is composed of a pressure control device. Through control thyristor trigger angle， the AC output fundamental voltage effective value of control to achieve pressure and speed adjustme