说明：  使用V/F原理的交流电机控制和简单的PWM算法 交流电机在连接到电源时只能以其额定速度运转，所以要改变转速必须改变电源频率。本篇应用文档展示了这些技术如何在AT90PWM3上简单的被实现，也说明了AVR RISC微处理器在电源控制方面的应用。
(Induction motors can only run at their rated speed when they are connected to the main power supply. This is the reason why variable frequency drives are needed to vary the rotor speed of an induction motor. The aim of this application note is to show how these techniques can be easily implemented on a AT90PWM3, an AVR RISC based microcontroller dedicated to power control applications. )