Correlative angles switching technique for switched reluctance motor drive systems

Switched reluctance machines with its uncomplicated structure, low cost, high reliability and fault tolerance, is struggling to gain higher market share almost in all electric machinery utilities. Its simplicity encouraged researchers to apply a wide variety of classic and intelligent control techniques. These techniques are used to control the speed and torque via appropriate determination of switching-on and switching-off angles, usually associated with applying chopping in between. However, the nonlinear nature of the machine forced the utilization of sophisticated models to assist speed and torque controllers to select proper switching angles. Especially at high speeds, the uncontrolled current during freewheeling may produce negative torque and consequently torque ripples. Considerable research efforts have been performed to reduce such ripples. In this paper, a new switching technique is proposed. The technique aims to deal with the current waveform during excitation and freewheeling as a whole via correlating the switching-on, switching-off and current-end angles using simple calculations. The restrictions and limitations imposed on each switching angle to mollify operation conditions are investigated. An extensive simulated study is carried out to validate the reliability of the proposed technique. The results show the effectiveness of the proposed control method for practical high-speed applications.