Trends in controlling variable-speed drives

摘要

Three-phase ac motors are becoming the popular choice for new designs, replacing electronically controlled drives in a wide range of applications. In the past, the dominant motors for variable speed drives (VSD) were universal brushed motors and single-phase ac induction motors (ACIMs). For these drives, motor speed is controlled through a triac, by adjusting the conduction angle. Such a control technique is very simple and does not place any special demands on a microcontroller. They typically use an 8-bit microcontroller.