Design and construction of a new SRM sensorless driver

A new sensorless circuit for Switched Reluctance Motor (SRM) is designed, constructed and tested in this paper. The circuit uses three steps to control the SRM. One of them is used in motor starting. The other one controls the motor in low speed and the third one is used in high speed. These steps are implemented by an inexpensive AVR microcontroller chip. An asymmetric bridge converter is used to excite the winding of the motor phases. The presented sensorless board is then constructed and tested on two SRMs which are three-phase 12 by 8 and three-phase 6 by 4 SRMs. The parameters of these motors which are required in sensorless techniques are obtained by Finite Element Method (FEM) analysis. The operational waveforms and results that are obtained in laboratory are illustrated in different figures.