Smooth Torque Speed Characteristic of Switched Reluctance Motors

Abstract

The torque ripple of switched reluctance motors (SRMs) is the main disadvantage that limits the industrial application of these motors. Although several methods for smooth-toque operation (STO) have been proposed, STO works well only within a certain torque and speed range because of the constraints of the supply voltage and peak current. Based on previous work that sought to expand the STO range, a scheme is developed in this study to determine the maximum smooth torque range at each speed. The relationship between the maximum smooth torque and speed is defined as the smooth torque speed characteristics (STSC), a concept similar to torque speed characteristics (TSC). STSC can be utilized to evaluate torque utilization by comparing it with TSC. Thus, the concept benefits the special design of SRMs, especially for the generation of smooth torque. Furthermore, the torque sharing function (TSF) derived from the proposed method can be applied to STO, which produces a higher smooth torque over a wider speed range in contrast to four typical TSFs. TSimulation and experimental results verify the proposed method.

Direct instantaneous torque control with wide operating range for switched reluctance motors

“…Within the constraints of the voltage and current, the optimal TSFs at two operating points (1 Nm, 300 r/min) and (2 Nm, 200 r/min) can be calculated by the iteration algorithm shown in Fig. 6 in [17]. The voltage profiles with respect to the optimal TSFs can be obtained by the formula (15) in [17].…”

“…6 in [17]. The voltage profiles with respect to the optimal TSFs can be obtained by the formula (15) in [17]. As explained in [17] the value of the voltage profile at every position should be less than the dc-link voltage, then the reference torque can be tracked completely and the torque ripple is estimated successfully.…”

“…In our previous work [17], the method of calculating the optimal TSF with lowest required voltage was proposed, and the widest operating range of STO was determined, as shown in Fig. 1.T o realise the widest operation, the optimal TSF at each operating point on the torque-speed plane should be optimised offline and be saved in the controller, which is seriously time and memory consuming.…”

Average torque control of switched reluctance machine drives for electric vehicles

“…With the advantages of rugged motor construction, large starting torque, wide speed range, inherent fault-tolerance capability and high operating efficiency, switched reluctance machine (SRM) is a remarkable candidate for electric drive systems of electric vehicles (EVs) and hybrid electric vehicles (HEVs) [1][2][3][4][5]. However, because of double saliency with concentrated stator windings and singly excited structure, SRM has larger torque ripple and noise than conventional motors [6,7].…”

Torque Ripple Minimization Scheme Using Torque Sharing Function Based Fuzzy Logic Control for a Switched Reluctance Motor

“…Therefore, many studies on reducing torque ripples have been carried out extensively [4][5][6][7]. One of the effective approaches to reducing the torque ripple is a torque sharing function (TSF) method [8][9][10][11]. Because each phase of the SRM is controlled independently, expected torque is divided into individual phase torque references.…”