Investigation of inverterless control of interior permanent-magnet alternators

Copyright © 2006 IEEEThis paper investigates the performance and control of a low-cost 6-kW concept demonstrator of an "inverterless" automotive alternator. This is based on a switched-mode rectifier (SMR) combined with a high-flux interior permanent-magnet (PM) machine. Duty cycle control of the SMR is described and the theoretical predictions are compared with open-loop experimental results. The efficiency of the concept demonstrator is examined as a function of speed and load. Control issues regarding automotive operation are discussed.Chong-Zhi Liaw, David M. Whaley, Wen L. Soong and Nesimi Ertugru

Analysis and design of energy storage for current-source 1-ph Grid-connected PV inverters

Copyright © 2008 IEEEThis paper examines the analysis and design of a DC link inductor for a current source 1-ph grid-connected photovoltaic (PV) inverter. Firstly the effect of voltage or current ripple on the PV array average output power is examined using a normalized PV output characteristic. Secondly the design of the inductor and in particular the trade-off between the PV array output power loss and the inductor copper loss are discussed. An inductor was built and a comparison of the calculated and measured loss breakdown is presented.G. Ertasgin, D.M. Whaley, N. Ertugrul and W.L. Soon

Fault tolerant motor drive system with redundancy for critical applications

Some of the recent research activities in the area of electric motor drives for critical applications (such as aerospace and nuclear power plants) are focused on looking at various motor and drive topologies. This paper presents a motor drive system, which provides an inverter topology for three-phase motors, and also proposes an increased redundancy. The paper develops a simulation model for the complete drive system including synthetic faults. In addition, the hardware details including the implementation of DSP based motor controller, inverter module, and brushless PM motor system are provided and some experimental results are presented.N. Ertugrul, W. Soong, G. Dostal and D. Saxo

Analysis and performance evaluation of an axial-field brushless PM machine utilising soft magnetic composites

Copyright © 2007 IEEEOne of the major research activities in electric machines involves the use of alternative magnetic materials. Soft magnetic composites (SMC) offer the advantages of 3D magnetic flux paths and low-cost manufacturing. This paper examines the analysis and modelling of a prototype axial-field permanent magnet machine which uses SMC. Measured parameters and performance with an inverter is compared to 3D finite-element simulations. © 2007 IEEE

Investigation of static eccentricity fault frequencies using multiple sensors in induction motors and effects of loading

A significant number of studies have been reported in the literature on the detection of eccentricity faults in induction machines; however these have generally used one type of sensor such as current or vibration, and not studied in detail the effect of loading. This paper examines the use of fault frequency components in the current, flux and vibration sensor signals with the aim of both detecting and estimating the severity of static eccentricity faults in the presence of load variations. The research is based on an extensive series of sensor measurements taken using a specially modified 2.2kW induction machine under varying conditions of static eccentricity and loading.R. Supangat, J. Grieger, N. Ertugrul, W.L. Soong, D.A. Gray, C. Hanse

Detection of broken rotor bar faults and effects of loading in induction motors during rundown

© Copyright 2007 IEEEThe detection of broken rotor bar faults based on the common steady-state Fourier transform technique is known to be dependent on the loading condition and the quality of the supply. This paper attempts to minimise these issues by utilising the induced voltage in the stator windings after supply disconnection. When the supply is disconnected, the stator current rapidly drops to zero and the only source of the stator induced voltage an instant after the supply disconnection is due to currents in the rotor. The rotor currents are sensitive to broken rotor bar faults and directly affect the rundown induced voltage in the stator windings. The performance of two different broken rotor bar detection techniques, based on the Fourier transform and the wavelet transform, are investigated over a wide range of loading conditions

Analysis of a segmented brushless PM machine utilising soft magnetic composites

© Copyright 2007 IEEESoft magnetic composites (SMC) is a magnetic material which offers the potential for innovative machine geometries and lower cost manufacturing. This paper examines the finite-element analysis and performance prediction of a segmented brushless permanent magnet machine based on SMC. Experimental results including the back-EMF waveform, iron loss and performance characteristics are used to validate the simulation results

Percutaneous septal ablation for left mid-ventricular obstructive hypertrophic cardiomyopathy: a case report

BACKGROUND: Mid-ventricular obstructive hypertrophic cardiomyopathy (MVOHC) is a rare type of cardiomyopathy. The diagnosis is based on the hourglass appearance on the left ventriculogram and the presence of pressure gradient between apical and basal chamber of the ventriculum on the hemodynamic assessment. CASE PRESENTATION: The present case represents successful percutaneous treatment with septal ablation to patient with MVOHC associated with systolic anterior motion of the mitral valve and obstruction at both the mid-ventricular and outflow levels. CONCLUSION: Alcohol septal ablation has been proposed as less invasive alternatives to surgery in patients with MVOHC