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ROBUST SPEED SENSORLESS INDUCTION MOTOR DRIVES
Geetha E.K,T.Thyagarajan,Vedam Subrahmanyam 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-
Induction motors are widely used in industry due to the fact that they are relatively cheap, rugged and maintenance free. As a consequence, much attention has been given to the motor torque and speed control. The control schemes available today require information regarding speed of the motor, which can either be obtained by using speed sensors or without speed sensors. Speed sensors have several disadvantages from the standpoint of drive cost, reliability, inertia and noise immunity. Advantages of eliminating speed sensors thus have been a strong motivation to develop speed sensor less induction motor drives for industrial drives. Several control strategies of sensor less control are available in literature. This paper is an attempt to explore the possibility of estimation of rotor speed with the help of extended Kalman filter trained recurrent Neural Network. The speed estimation is made robust by simultaneously adapting the rotor resistance and rotor flux which are also done by the same Neural Network. The training is very fast as it requires only one iteration. The proposed scheme is studied on an induction motor and it gives better performance as compared to the already existing algorithms in the literature.
Analysis and simulation of Matrix Converter Using PSIM
Ashwin Kumar Sahoo,J. Meenakshi,S. S Dash,T. Thyagarajan 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-
Matrix Converter, a direct AC/AC Converter replaces the multiple conversion stages and the intermediate energy storage element of the indirect converters by a single power conversion stage, thus being a single stage converter. Matrix Converters employ an array of controlled bidirectional switches as the main power elements to create a variable output voltage system with unrestricted frequency. This paper attempts to give an overview of Matrix Converters and examines the types, features, merits and limitations of such Converters. It presents the basic operating principle of a Single Phase Matrix Converter, Two Phase to Single Phase Matrix Converter, Three Phase to Single Phase Matrix Converter and Three Phase to Three Phase Matrix Converter. The paper also introduces a topology of a Single Phase Matrix Converter , Two Phase to Single Phase Matrix Converter, Three Phase to Single Phase Matrix Converter and Three Phase to Three Phase Matrix Converter in PSIM software environment and analyses the output of the converter for different frequencies. Further, it examines the output voltage of a Single Phase Matrix Converter synthesized using the Sinusoidal Pulse Width Modulation (SPWM) technique. All simulations have been carried out in POWERSIM.
Durable keratin-based bilayered electrospun mats for wound closure
Singaravelu, Sivakumar,Ramanathan, Giriprasath,Muthukumar, Thangavelu,Raja, M. D.,Nagiah, Naveen,Thyagarajan, Sitalakshmi,Aravinthan, Adithan,P., Gunasekaran,Natarajan, T. S.,V. N. Geetha Selva, Ganga The Royal Society of Chemistry 2016 Journal of Materials Chemistry B Vol.4 No.22
<P>A bilayered nanofibrous scaffold with rapid wound healing properties is found to be suitable for tissue regeneration applications. The objective of this study is to reveal the fabrication of a poly(3-hydroxybutyric acid) (P)-gelatin (G) nanofibrous mat through electrospinning, with a horn keratin-chitosan-based biosheet (KC) as a bilayered nanofibrous scaffold. The mupirocin (D)-loaded horn KC biosheet (KCD) acts as the primary layer over which PG nanofibers were electrospun to act as the secondary layer. It is shown that this engineered bilayered nanofibrous scaffold material (KC-PG) should fulfill the functions of the extracellular matrix (ECM) by elucidating its function<I>in vitro</I>and<I>in vivo</I>. The bilayered nanofibrous scaffold was designed to exhibit improved physiochemical, biological and mechanical properties, with better swelling and porosity for enhanced oxygen permeability, and it also exhibits an acceptable antibacterial property to prevent infection at the wound site. The bilayered nanofibrous scaffold assists in better biocompatibility towards fibroblast and keratinocyte cell lines. The morphology of the nanofibrous scaffold aids increased cell adhesion and proliferation with cell material interactions. This was elucidated with the help of<I>in vitro</I>fluorescence staining against both cell lines. The bilayered KCD-PG nanofibrous scaffold material gives accelerated wound healing efficiency during<I>in vivo</I>wound healing. The results showed the regulation of growth factors with enhanced collagen synthesis, thereby helping in faster wound healing.</P>