介绍了交流调速及其相关技术的发展现状和发展趋势，以及交流调速系统的主要控制策略。选用工业变频器用异步电机作为研究对象，利用坐标变换理论，分析了异步电机在三相静止坐标系、两相静止与旋转坐标下的电机基本数学模型及其矢量控制原理。-The present situation and development trend of AC speed control and its related technology are introduced, and the main control strategies of AC speed control system are introduced. The basic mathematical model of the motor and its vector control principle are analyzed by using the coordinate transformation theory, which is based on the three-phase stationary coordinate system, two-phase stationary and rotating coordinates.