Loss Distribution on Solid Pole Plates of Wound-Rotor Synchronous Motors Fed From Inverters Using Direct Torque Control

The use of VSD (variable speed drives) is becoming prominent in industry as it has the benefit of being more energy efficient than conventional process-control mechanisms (such as throttling). VSD usually rely on the use of inverters to produce the required frequency output, which contains time harmonics that eventually induce excess losses in the machine. These losses are the subject of analysis in this study. The results show that it is possible to influence the induced current magnitude (due to the space and time harmonics) through proper design modifications, as to reduce the consequent losses. The paper focuses specifically on DTC (direct torque control) VSD application on solid pole plate synchronous machines. One of the observed effects is that the time and space harmonics are distributed differently on the pole plates.