Variable Speed Control of Wound Rotor Synchronous Motor with MTPA Technique

In today’s world, electrical machines are essential in various industries and our daily lives. The popular choice is the permanent magnet synchronous machine (PMSM), however it has some drawbacks. Since PMSMs require rare-earth elements (or other special alloys), a magnet-free alternative motor called wound rotor synchronous machine (WRSM) used to reduce reliance on foreign industries. The field current of a WRSM passing through the rotor windings generates the magnetic field which offers flexibility in flux linkage. The WRSMs have also some disadvantages compared to PMSMs such as increased rotor losses because of the field winding, and larger size. This study presents a modeling and control methods of WRSMs, highlighting the differences in the control algorithm. The control methods for WRSMs are similar to PMSMs like zero d-axis current (ZDC) control and maximum torque per ampere (MTPA) control. But the independent control of the field current allows for more flexible field-oriented control in high-speed applications of a WRSM.