Enhancement of Permanent-Magnet Synchronous Machines Torque Estimation Using Pulsating High-Frequency Current Injection

Torque estimation in permanent-magnet synchronous machines is highly desirable in many applications. Torque produced by a permanent-magnet synchronous machine depends on the permanent-magnets' flux and dq-axes inductances. Consequently, precise knowledge of these parameters is required for proper torque estimation. This article proposes the use of a high-frequency signal for both PM flux and dq-axes inductances estimation. The high-frequency signals will be injected in the stator via an inverter superposed on top of the fundamental excitation. The proposed method can be used without interfering with the normal operation of the machine, the results being highly insensitive from machine's working condition.