Mbika Muteba

Torque ripple minimization in synchronous reluctance motor using a sinusoidal rotor lamination shape

A Synchronous Reluctance Motor (SynRM), which has sinusoidal rotor lamination shape in the axial direction, is proposed. The sinusoidal lamination shape is utilized to vary the magnetic flux in the qr-axis direction. Therefore, cancelling some torque harmonics produced by slotting effects. The stator geometry of a 1.5 kW, conventional three-phase squirrel cage induction motor, with distributed double layer winding, chorded by one slot, is used for both basic and proposed models. Due to the axial geometry design of sinusoidal lamination shape for the proposed model, 3-D Finite Element Method (FEM) is used for dynamic analysis. From the FEM results, it evidenced that with current vector angle of 45° electric, the proposed model reduced the torque ripple content by more than 60 % and still maintained the average torque.

Effect of double-triple winding layout on axially-laminated anisotropic rotor synchronous reluctance motors

This paper deals with the effect of the combination of double and triple layer (DTL) winding configurations on axially laminated anisotropic (ALA) rotor synchronous reluctance motors. Three ALA rotor shapes are opted in this paper to evaluate the airgap flux density, torque average and torque ripple contents. The stator geometry of a 4-pole, 1.5 kW, conventional three-phase squirrel cage induction motor, having 36 slots is used. 2-D Finite Element Method (FEM) is utilized to analyse the performance of the machines. From the FEM results, it evidenced that DTL winding configuration reduced the airgap flux density Total Harmonic Distortion (THD), improved torque average and dropped the torque ripple contents in all three ALA rotor synchronous reluctance motors.

Based 3D finite element analysis of a synchronous reluctance motor with sinusoidal rotor shape

This paper deals with the numerical analysis of the Synchronous Reluctance Motor (SynRM) with sinusoidal rotor shape in the axial direction using the 3D Finite Element Method (FEM), and presents the airgap magnetic flux governing equation derived from Kelvin-Stokes theorem. In the Finite Element Analysis (FEA) the airgap flux density, machines performance indexes, the torque and its ripple contents are presented. In this paper three motors having different rotor anisotropies are modelled and analyzed. The SynRM with sinusoidal rotor shape (SynRM3) FEA results are compared with the conventional SynRM without cut-off (SynRM1) and SynRM with cut-off (SynRM2) on the q-axis. The stator geometry of a 5.5 kW, 4-pole, 50-Hz, 8 A, conventional three-phase squirrel cage induction motor, with distributed double layer winding chorded by a single slot is used to model all three SynRMs.

Start-up analysis of synchronous reluctance motors with uniformly distributed cage bars in the rotor structure

This paper deals with the start-up analysis of a synchronous reluctance motors (SynRMs) with uniformly distributed cage bars in the rotor structure. Two SynRMs are modelled using 2D Finite Element Method (FEM). The rotors of both motors are built with stamped conventional steel laminations having flux barriers. The first motor model (SynRM1) has closed rotor slots above each flux barrier separated with magnetic bridges, and the second (SynRM2) is fitted with cage bars in the rotor air-barriers. The motors magnetic conditions are analysed under transients and steady-state operations. The Finite Element Analysis (FEA) results show that the SynRM2 has higher peak-to-peak accelerating torque, but has higher synchronization time. The results also provide that high steady-state average torque (Tave.) and lower torque ripple (Trip.) contents are achieved by the fitted with cage bars in the rotor air-barriers.

Effect of rotor bar shape on the performance of three phase induction motors with broken rotor bars

A slight change in time phase shift between currents in adjacent rotor end ring segments directly affects the characteristics of the airgap torque in a squirrel cage induction machine (SCIM). On the other hand the rotor slot geometrical permeance has a strong impact on the rotor bar leakage inductance. This paper deals with effect of different rotor bar types (geometrical shapes) when a SCIM operates under healthy and broken rotor bars condition. The three phase squirrel cage induction machine is designed and modelled using two dimension (2D) finite Element Model (FEM). Static and dynamic analysis are performed in order to determine the target performance indexes such as transient torque, steady state torque, torque ripple, air-gap flux density, power factor and efficiency. The Finite Element Analysis (FEA) results evidence that the rotor bar shape can be optimized, such that the SCIM is yet to produce good performance when the phase shift between neighbouring bars e.m.f is changed due to rotor bar breakage.

Investigation into effects of a novel rotor cut-off design for synchronous reluctance machines

This paper presents an investigation into the effects of a novel rotor cut-off design on the performance of a synchronous reluctance machine. The rotor design consists of a sinusoidal lamination shape in the axial direction thereby varying the magnetic flux in the g-axis direction and reducing torque harmonics due to slotting effects. The presented study uses single-factor experimental design, with Analysis of Variance (ANOVA), and Finite Element Analysis (FEA) to quantitatively and qualitatively assess the effects of the rotor cut-off on the torque, torque ripple, saliency, power factor and efficiency of the machine. Results of the investigation indicate that although variation in the rotor cut-off design significantly reduces the torque ripple, the effects on the average output torque, saliency, power factor of the machine are relatively insignificant.

Optimal parameter inference method for effective design of synchronous reluctance machines

This paper presents a method for evaluating, both qualitatively and quantitatively, the effects of specific rotor design parameters on the performance of a Synchronous Reluctance Machine (SynRM). The method uses multi-factor experimental design, with Analysis of Variance (ANOVA), and Finite Element Analysis (FEA) to determine the optimal rotor design parameter according to a specific objective. Using this method, two factors — rotor flux barrier pitch angle and barrier width — are selected at simultaneously varied levels for assessment with the aim of analyzing the response variables, which are, the average torque and torque ripple. Results from the investigation show that the influence of the rotor flux barrier pitch angle on the torque ripple is more statistically significant than the influence of the barrier width. However, the effect of the barrier width on the average torque is more significant.

Effect of capacitive auxiliary winding on a three-phase induction motor performance behaviour

This paper investigates the effect of a capacitive three-phase auxiliary winding on the target variables of a three-phase squirrel cage induction motor (SCIM). The three-phase auxiliary winding is only magnetically coupled to the stator main winding. The three-phase SCIM is modelled using 2D Finite Element Method (FEM). The flux density distribution is numerically computed through the magnetostactic solver, and the other target variables of interst such as the efficiency, power factor and torque are obtained through ac magnetic-transient solver. A conventional 4 kW, 50-Hz, and 4-pole three-phase SCIM is modified to accommodate both main and auxiliary windings in the stator slots. The results obtained from Finite Element Analysis (FEA) are compared with results from practical measurement (PM). From both simulation and experimental results, it is noted that the capacitive auxiliary winding has not only enhanced the power factor, but it also has a significant impact on the efficiency, torque and other electromagnetic parameters of the three-phase SCIM.

Transient analysis of a start-up synchronous reluctance motor with symmetrical distributed rotor cage bars

This paper deals with the transient analysis of direct-on-line synchronous reluctance motor (SynRM) with symmetrical distributed rotor cage bars. Finite Element is utilized to analyze the transient behavior in both synchronized and unsynchronized regimes of the direct-on-line SynRM. In this paper two Synchronous reluctance motors are modelled and analyzed. The first motor is referred to as SynRM1. It has cage bars in the rotor iron structure above the flux barrier and placed near the machines airgap. The second is labelled as SynRM2, where the cage bars are inserted in the flux barriers. The characteristic behavior in synchronized and unsynchronized regimes of both SynRMs are obtained on no-load and full-load, through ac magnetic-transient solver. Other performance indexes of interest, such as the efficiency and power factor are also analyzed.

Effect of rotor barrier pitch angle on torque ripple production in synchronous reluctance machines

This paper analyses the effect of rotor barrier pitch angles on torque ripple production in Synchronous Reluctance Machines (SynRMs), with the objective to reduce torque ripple contents in medium size ground Electric Vehicles (EVs). While keeping major-design parameters constant, the barrier pitch angle is varied by a quarter of the stator slot pitch. Three SynRMs having different rotor barrier pitch angles are designed and modeled using 2D Finite Element Method (FEM). The specifications of a traditional 5.5 kW, three-phase, 50 Hz, induction machine are used to design and model the SynRMs. Torque ripple reduction of ± 48 % is achieved for barrier pitch angles of 15 and 17.5 mech, when the machines operate at current space phasor angle of 45 electric.