Copyright (c) 2010 All rights reserved. http://works.bepress.com/mukhtar_ahmad Recent documents in Mukhtar Ahmad en-us Tue, 07 Sep 2010 01:30:21 PDT 3600 http://works.bepress.com/mukhtar_ahmad/22 http://works.bepress.com/mukhtar_ahmad/22 Sun, 05 Sep 2010 08:27:39 PDT Mukhtar Ahmad http://works.bepress.com/mukhtar_ahmad/21 http://works.bepress.com/mukhtar_ahmad/21 Sun, 05 Sep 2010 08:21:57 PDT Mukhtar Ahmad Books http://works.bepress.com/mukhtar_ahmad/20 http://works.bepress.com/mukhtar_ahmad/20 Tue, 12 Feb 2008 21:26:24 PST Permanent magnet synchronous machines are becoming attractive in many industrial applications due to their high torque to inertia ratio, higher efficiency , and power density . Interest in Multi-phase motor drives has considerably increased during last few years. The main applications of multi-phase machines are in electric traction, electric vehicles, and hybrid vehicles. Multi-phase motor drives have many advantages including higher reliability and power density, and lower torque pulsations at higher frequencies Mukhtar Ahmad Published Papers in Journals http://works.bepress.com/mukhtar_ahmad/19 http://works.bepress.com/mukhtar_ahmad/19 Thu, 07 Feb 2008 05:43:36 PST Abstract Multi-phase ac motor drives are nowadays considered for various applications, due to numerous advantages that they offer when compared to their three-phase counterparts. In principle, control methods for multi-phase machines are the same as for three-phase machines. Variable speed induction motor drives without mechanical speed sensors at the motor shaft have the attractions of low cost and high reliability. To replace the sensor, information of the rotor speed is extracted from measured stator currents and voltages at motor terminals. Vector controlled drives require estimating the magnitude and spatial orientation of the fundamental magnetic flux waves in the stator or in the rotor. Open-loop estimators and closed-loop observers are used for this purpose. They differ with respect to accuracy, robustness, and sensitivity against model parameter variations. This paper analyses operation of an open-loop and model reference adaptive system (MRAS)-based sensorless control of vector controlled five-phase induction machine with current control in the stationary reference frame. The MRAS-based sensorless operation of a three-phase induction machine is well established and the same principle is extended in this paper for an IRFOC five-phase induction machine. Performance, obtainable with hysteresis current control, is illustrated for a number of operating conditions on the basis of simulation results. Full decoupling of rotor flux control and torque control is realised. Dynamics, achievable with a five-phase vector controlled induction machine, are shown to be essentially identical to those obtainable with a three-phase induction machine. Experimental verification is also provided. Mohammad Rizzwan Khan Article in Press http://works.bepress.com/mukhtar_ahmad/18 http://works.bepress.com/mukhtar_ahmad/18 Fri, 14 Dec 2007 07:44:11 PST The principle of operation of reluctance machines are known for a long time. In 1838 a locomotive was driven by such a motor in Scotland. The stepper motor which also works on the principle of variable reluctance was patented by CL Walker in 1920.The basic concepts of switched reluctance motors in present form were first introduced by SA Nasar in his paper in Proceedings of IEE in 1969. During late 70’s and 80’s, as fast switching devices became available, the applications of SRM have increased manifold. Due to their simple and rugged topology these motors are finding applications in consumer appliances, auto industries, and defence. Presently Ford motor company is using SRM in power assisted steering system. The slow development in commercialization of these motors was mainly due to the need to have specialized design, and requirement of a sensor to control the speed. The other disadvantages are the torque ripple and acoustic noise Now these disadvantages have been minimized by improving the design, sensorless drives have been developed, and many manufacturers are producing the SRM, making it easily available motor. The switched reluctance motors have many advantages, e.g. high efficiency, can be designed for ratings from few watts to M watts and can be employed in harsh working environments. Mukhtar Ahmad Lecture http://works.bepress.com/mukhtar_ahmad/17 http://works.bepress.com/mukhtar_ahmad/17 Mon, 09 Jul 2007 06:08:05 PDT Kartik Basu Published Papers in Journals http://works.bepress.com/mukhtar_ahmad/16 http://works.bepress.com/mukhtar_ahmad/16 Fri, 29 Jun 2007 08:42:08 PDT Mukhtar Ahmad Popular Science Articles http://works.bepress.com/mukhtar_ahmad/15 http://works.bepress.com/mukhtar_ahmad/15 Fri, 29 Jun 2007 08:35:49 PDT Mukhtar Ahmad Articles Published Papers in Journals http://works.bepress.com/mukhtar_ahmad/14 http://works.bepress.com/mukhtar_ahmad/14 Fri, 29 Jun 2007 08:31:00 PDT Mukhtar Ahmad Conference Papers http://works.bepress.com/mukhtar_ahmad/13 http://works.bepress.com/mukhtar_ahmad/13 Fri, 29 Jun 2007 08:16:01 PDT Mukhtar Ahmad Articles Published Papers in Journals http://works.bepress.com/mukhtar_ahmad/12 http://works.bepress.com/mukhtar_ahmad/12 Mon, 25 Jun 2007 22:52:24 PDT Mukhtar Ahmad Articles Published Papers in Journals http://works.bepress.com/mukhtar_ahmad/11 http://works.bepress.com/mukhtar_ahmad/11 Mon, 25 Jun 2007 22:48:55 PDT Mukhtar Ahmad Conference Papers http://works.bepress.com/mukhtar_ahmad/10 http://works.bepress.com/mukhtar_ahmad/10 Mon, 25 Jun 2007 22:46:45 PDT Mukhtar Ahmad Conference Papers http://works.bepress.com/mukhtar_ahmad/9 http://works.bepress.com/mukhtar_ahmad/9 Mon, 25 Jun 2007 00:33:52 PDT Mukhtar Ahmad Conference Papers http://works.bepress.com/mukhtar_ahmad/8 http://works.bepress.com/mukhtar_ahmad/8 Mon, 25 Jun 2007 00:31:00 PDT Mukhtar Ahmad Popular Science Articles http://works.bepress.com/mukhtar_ahmad/7 http://works.bepress.com/mukhtar_ahmad/7 Sun, 24 Jun 2007 01:00:25 PDT Mukhtar Ahmad Popular Science Articles http://works.bepress.com/mukhtar_ahmad/6 http://works.bepress.com/mukhtar_ahmad/6 Sun, 24 Jun 2007 00:55:14 PDT Wasim Ahmad Articles Published Papers in Journals http://works.bepress.com/mukhtar_ahmad/5 http://works.bepress.com/mukhtar_ahmad/5 Sat, 23 Jun 2007 21:40:04 PDT Mukhtar Ahmad Articles Published Papers in Journals http://works.bepress.com/mukhtar_ahmad/4 http://works.bepress.com/mukhtar_ahmad/4 Sat, 23 Jun 2007 21:16:06 PDT Mukhtar Ahmad Articles Published Papers in Journals http://works.bepress.com/mukhtar_ahmad/3 http://works.bepress.com/mukhtar_ahmad/3 Sat, 23 Jun 2007 09:19:56 PDT Mukhtar Ahmad Articles Published Papers in Journals