Industry application of zero-speed sensorless control techniques for PM synchronous motors

This paper presents the state of the art in the area of industrial applicat ions of sensorless control for permanent-magnet synchronous motor (PMSM) dr ives. A new emerging technology is becoming mature to come to the market, b ased on high-frequency signal injection, that makes it possible to achieve zero-speed operation without increasing the complexity acid the cost of the system. After an overview of major theoretical principles of sensorless co ntrol of PMSMs, the paper focuses on the practical implementation of one of the previously described high-frequency injection techniques in both salie nt and nonsalient PM machines. Experimental results are presented, includin g useful hints for practical implementation.