Dan-Valentin Nicolae

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.

Brushless direct current motor efficiency characterization

The use of a compact lightweight efficient propulsion system is one of the main technological requirements for a long endurance electric Unmanned Aerial Vehicle (UAV). Currently the most popular trend is to use a permanent magnet brushless direct current (BLDC) model motor. This type of motor is used because of its efficiency which can be greater than 90% when optimally driven. However the majority of manufacturers do not provide adequate performance response profiles throughout the specified motor applied voltage range. This paper presents a methodology to characterize the BLDC efficiency.

Characterization and modeling of an RMS-DC solid-state thermal converter

The Root Mean Square measurements of alternating signal of any waveform are frequently done by means of thermal transfer instruments. The principle of these thermal transfer instruments is to transfer the heating energy of resistive load to a temperature-sensing element. The dc output of the sensor reflects the amount of electrical power (ac or dc) applied to the input. The paper addresses the characterization and modelling of an rms-dc thermal converter of a solid state technology type at various frequencies. The theoretical and simulation analysis is carried out to outline the factors influencing the transfer characteristics of the converter device in the dc and ac input regimes.

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 modelling of planar thermal converter device

The root mean square (rms) measurement of alternating voltage of any waveform is frequently done by means of thermal transfer instruments. The principle of these thermal rms converters is to transfer the heating energy of resistive load to a temperature-sensing element. The dc voltage output of the sensor reflects the amount of electrical power (ac or dc) applied to the input. This paper is addressing the modelling of a thermal converter device in planar technology using finite element platform. The original approach of this study capitalizes on introduction of a resistive thermal sensing element of a planar type to provision the thermal-conversion response to the active power dissipated on the 3D stratified non-reactive heater structure. Through iterative multi-physics simulations, model properties and dimensions have been evaluated and optimized.

An approach to quantify the technical impact of power quality in medium voltage distribution systems

This paper provides a useful guidance in the interpretation and analyses of the technical impact of power factor correction in a power system. It is intended to raise awareness in order to achieve correct measurements, calculations and the key dynamics of the power system when quantifying the impact of power quality (PQ) in a non-linear power system. This paper is therefore targeting the power producing utilities, municipalities and the bulk end users of electricity.

Diagnostic methods of frequency response analysis for power transformer winding a review

Monitoring and diagnosis of power transformers in power systems have been investigated and discussed for the past decades. Earlier detect power transformer winding failures is recommended for both manufacturing process and also for power system operators. One of the most powerful and accurate tool for sufficient winding deformation detection is considered Frequency Response Analysis (FRA) among other diagnostic methods. In this paper a review of diagnostic methods of FRA for power transformer winding are presented. Different methods of transformer winding diagnosis, with their benefits and drawbacks where investigated. Moreover, possible windings failures, diagnostic methods of FRA in Off-line and On-line power transformers, detailed advantages and disadvantages of two major types of FRA are presented. The paper was able to show that some uncertainties have not been eliminated completely.