杨金花

[摘    要]在电力拖动系统中，电动机的运行状态是机电专业学习的重要内容之一。然而，现行教材对此部分内容进行了大幅度删减，特别是对制动的讲解，片面地只关注制动停车，删除了对制动运行状态的分析，容易导致学生对所学知识形成零散片段。另外，对于动态转化过程，由于实训条件、知识结构及教学进度所限，进行定量分析收效甚微。基于上述原因，文章转变传统教学思路，依据电磁转矩与转子转速之间的函数关系，把抽象的工作原理转化为坐标系中形象的运行特性曲线，帮助学生掌握不同状态下的运行过程;补充了教材中相关理论的不足，使学生对相关知识得以系统性学习。

[关键词]教学实践;工作原理;定性分析;运行状态

[中图分类号]TM343 [文献标志码]A [文章编号]2095–6487（2021）10–0–03

From Abstraction to Image——qualitative Analysis and Teaching Practice

of Three-phase Asynchronous Motor Running State

Yang Jin-hua

[Abstract]In the electric drive system， the running state of the motor is one of the important contents of the electromechanical professional study. However， the current textbooks have greatly deleted this part of the content， especially the explanation of braking. It only focuses on braking and stopping， and deletes the analysis of the braking operation state， which may easily lead to scattered knowledge of the students. Fragment. In addition， for the dynamic transformation process， due to the limitations of training conditions， knowledge structure and teaching progress， quantitative analysis has little effect. Based on the above reasons， the article changes the traditional teaching thinking， based on the functional relationship between the electromagnetic torque and the rotor speed， transforms the abstract working principle into the vivid operating characteristic curve in the coordinate system， to help students master the operating process under different conditions; Supplement Insufficiency of related theories in the textbooks， so that students can learn related knowledge systematically.

[Keywords]teaching practice; working principle; qualitative analysis; operating status

文章创新地提出了一套通俗易懂的讲授方法，将抽象的工作原理依据电磁转矩M与转子转速n的函数关系，转变为M-n坐标系中的运行特性曲线，使复杂的动态变化过程得以直观形象地呈现出来，从而更好地帮助学生掌握所学知識。文章以三相绕线式异步电动机为例进行详细阐述。

1 三相异步电机运行状态的机械特性

式（1）为M、n的函数关系表达式[1]M=f（n），以此为依据绘制出图1中的各种曲线。这些曲线即为不同运行状态下的机械特性，可以直观形象地表述二者之间的变化关系。M=f（n）的数学表达式如下所示：

                   （1）

式（1）中，M为电磁转矩，单位N/m;U1是电源电压，单位V;p是磁极对数;s是转差率;f1为电源频率;R1、X1为定子绕组的电阻、电抗;R'2、X'2是转子绕组的折算电阻、电抗。……