基于单片机的交流电机保护器的设计.docVIP

摘 要 电动机因具有结构简单、价格低廉、使用维护方便等优点，在国民经济各方面被广泛采用。然而，由于供电状态和机械负荷的多变性，使得电动机的故障率较高，不仅会损坏电动机本身，而且会影响整个生产，造成较大的经济损失。因此，电动机的安全运行对保证厂矿企业的正常生产是非常重要的。 本文首先分析了异步电动机的常见故障，以对称分量法为依据，采用检测过流幅值、负序电流、零序电流的方法，得出了电动机故障的准确判据，确定了各种故障的保护措施，对电动机实现了短路、堵转、过热、负序电流、零序电流、低电压、过电压、启动时间过长、频繁启动、漏电闭锁等保护功能。 本文以8位单片机AT89C51做微处理器，AT89C51单片机内置128字的RAM和4K字的ROM，可以进行外部扩展数据存储器和程序存储器，具有性能较好的I/O、运算等功能，有合适的指令系统，能够实现电机智能保护，电路简单，功能齐全。 为了实现电机分布检测和控制的要求，控制系统具有便于集中管理和信息共享的特点。 关键词：电动机，智能保护，单片机AT89C51 Abstract Motor has many advantages，such as simple structure, being cheap，maintaining and using conveniently and so on, so it is adopted extensively in the different fields of national economy. However, because of supply power state and mechanical load ge七ting changeable, it makes the malfunction rate of the motor very high.The malfunction will damage the motor, but also influence the whole production,cause the enormous economic losses. So, in order to guarantee the normalproduction of the industrial enterprise, the safe operation of the motor is very important. This text has analyzed the common malfunction of the asynchronous motor at first. And then it, which is based on symmetrical weight theory, has drawn accurate criterion of the trouble of the motor, confirmed the protective measures of different troubles. Finally, it has realized kinds of protection functions, such as short-circuit protection, rotate-stop protection, over-hea rotection,negative current protection, zero current protection, low-voltage protection,over-voltage protection, overlong start-up time protection, frequent start-up protection, lock protection of electric leakage and so on. This text has selected 8-bit computer AT89C51 as micro-controller. The single-chip computer has built-in RAM and ROM, and can need to expand the RAM and ROM. Having strong function and high-efficient ins ruction system, it has realized intelligence protection of the motor.Its circuit is simple and its function is comprehensive. In order to realize the