A low voltage sensorless Switched Reluctance Motor drive using flux linkage method

The inherent vulnerability to mechanical failures, extra cost, and size associated with external position sensors such as optical encoders and Hall sensors has motivated many researchers to develop sensorless control techniques for SRM drives. In this paper a flux linkage method and dual layer controller is developed to estimate rotor position and speed of a low-voltage Switched Reluctance Motor (SRM) drive. The basic concept of this application is that of a sensorless speed closed loop with an inner current loop using flux linkage position estimation. The voltage drop on the power devices is more significant in case of low voltage then in case of the high voltage drive. This voltage drop needs to be considered in the algorithm. Simulations and real-time experimental results given in this paper shows that the proposed position estimation method can provide accurate and continuous position information over a wide range of speeds, even in low speed applications. To ensure a sure operation, a start up algorithm is also included. The proposed method was implemented and tested by using a digital signal processor 56F807EVM from Freescale Semiconductor Company and an 8/6 switched reluctance motor coupled with a brushless DC motor as load. The software has been developed in C language.