用软起动器实现交流异步电动机的节能运行

通过分析交流异步电机软起动器的工作原理，在Intel 89C51单片机基础上，对软起动器硬件扩展，可实现对电机运行的各参数进行设定和修改。借助功率因数测量电路和软起动器的晶闸管调压电路组成的闭环反馈系统，单片机可以根据负载变化相应地调整软起动器输出电压，使电机始终工作在设定功率因数下，从而实现交流异步电机的恒功率因数控制，达到节能运行的目的。

Energy Efficient Operation of AC Asynchronous Motor by soft Starter

Through the analysis of the working principle of asynchronous motor's soft-starter, a hardware expansion of the soft-starter was made based on single-chip microcomputer Intel-89C51 to realize the set up and alteration of the motor operation parameters. By means of a close-circuit feedback system composed of a power factor measuring circuit and a soft-starter's thyristor voltage modulator, the single-chip microcomputer can make corresponding adjustment of the output voltage of the soft-starter according to the load change, enabling the motor to keep running at the set power factor so as to realize a constant power factor control of AC asynchronous motor and gain the goal of energy-efficient running.