Switched Reluctance Motor (SRM) is known for its robust. simple. and reliable structure. It is a doubly salient motor. and the rotor has neither winding nor magnet. which leads to a simple structure and low maintenance cost. High startup torque and high-power density are other worth-mentioning benefits for SRM. Based on the points that are mentioned. SRM is a suitable choice for electric vehicles. high-speed applications and a wide range of speed variation. SRM has nonlinear magnetic characteristics; therefore. the linkage flux. magnetic inductance. and electromagnetic torque are nonlinear functions of the stator current and rotor position. As a consequence of the non-linear features. SRM demands a front-end converter to establish accurate Switching algorithm. The non-linear nature of SRM control dictates that the phase currents have pulsating waveform. Having considered these points. SRM suffers from torque ripple. vibration and acoustic noise.The presence of rectifier and semiconductors in SRM drive makes the grid side current extremely distorted and non-sinusoidal. Problems arising from current harmonics includes increasing losses and overheating and isolating problems iequipment.In order to improve input current quality and motor performance in terms of torque and vibration. the three-level Vienna rectifier is utilized as front-end converter in the proposed drive system. Vienna rectifier is capable of providing power factor correction. output voltage regulation. low number of elements and dual-output terminal. This converter offers the dual-output terminals in order to separate magnetizing and demagnetizing paths in SRM. Therefore. by applying a boosted negative voltage. fast demagnetization is performed. implementing this technique result in not only reduction of the vibration amplitude at the point of commutation. but also prevents the rotor from entering the negative slope of the inductance and generating negative torque.In the proposed drive system. a switching algorithm with linear and cosine function for switches’ duty cycle is designed to apply a modulated negative voltage to motor phase as demagnetizing voltage. It should be noted that the average of demagnetizing voltage is directly related to the motor speed and its amplitude is between the half and total voltage of the DC link. In addition, fast demagnetization allows the average torque and output power to be increased by selecting the appropriate turn-off angle. The results obtained from theimulations and implementation of the laboratory model of the proposed drive system confirm the accuracy of the proposed method. 1-Switched reluctance motor, 2-PFC, 3-Vienna rectifier, 4-Fast demagnetization.,5-Vibration and acoustic noise.
