To develop an efficient variable speed compressor motor system

This research presents a proposed new method of improving the energy efficiency of a Variable Speed Drive (VSD) for induction motors. The principles of VSD are reviewed with emphasis on the efficiency and power losses associated with the operation of the variable speed compressor motor drive, particularly at low speed operation.The efficiency of induction motor when operated at rated speed and load torque is high. However at low load operation, application of the induction motor at rated flux will cause the iron losses to increase excessively, hence its efficiency will reduce dramatically. To improve this efficiency, it is essential to obtain the flux level that minimizes the total motor losses. This technique is known as an efficiency or energy optimization control method. In practice, typical of the compressor load does not require high dynamic response, therefore improvement of the efficiency optimization control that is proposed in this research is based on scalar control model.In this research, development of a new neural network controller for efficiency optimization control is proposed. The controller is designed to generate both voltage and frequency reference signals imultaneously. To achieve a robust controller from variation of motor parameters, a real-time or on-line learning algorithm based on a second order optimization Levenberg-Marquardt is employed. The simulation of the proposed controller for variable speed compressor is presented. The results obtained clearly show that the efficiency at low speed is significant increased. Besides that the speed of the motor can be maintained. Furthermore, the controller is also robust to the motor parameters variation. The simulation results are also verified by experiment

Pulsed magnetic flux compression power supplies for hypervelocity powder deposition

After reviewing the process of hypervelocity plasma deposition using augmented railgun technology, the paper presents several new concepts of pulsed rotating electric generators designed to power, on an almost continuous basis, the laboratory system designed and built at The University of Texas Center for Electromechanics (UT-CEM), which successfully validated the method and conducted proof-of-principle experiments. The two different rotating, repetitive pulsed power supplies described in the paper are: (1) an actively compensated flux compressor-alternator (actively compensated compulsator) and (2) a dc machine with series excitation, which so far did not have any application as a generator but proves, due to its self-excitation particularities, to be an almost ideal power source for the railgun. It needs to be emphasized that the augmented railgun and the actively and passively compensated compulsators represent almost mature technologies due to the continuous development of electromagnetic launch technology by the U.S. Department of Defense and especially by the U.S. Army – ready to be applied to many advanced civilian applications as it is the case with the hypervelocity powder railgun accelerators for surface conversion.Center for Electromechanic

US Navy program in small cryocoolers

A Navy program to develop fractional-watt cryocoolers capable of operating below 10 K is discussed. Several varieties of Stirling coolers were built and are under evaluation. In addition, helium gas compressors designed for use with small, closed cycle Joule-Thomson coolers are under development. An overview of the technical aspects of the program are presented

MHD performance calculations with oxygen enrichment

The impact of oxygen enrichment of the combustion air on the generator and overall plant performance was studied for the ECAS-scale MHD/steam plants. A channel optimization technique is described and the results of generator performance calculations using this technique are presented. Performance maps were generated to assess the impact of various generator parameters. Directly and separately preheated plant performance with varying O2 enrichment was calculated. The optimal level of enrichment was a function of plant type and preheat temperature. The sensitivity of overall plant performance to critical channel assumptions and oxygen plant performance characteristics was also examined

Fully superconducting rectifiers and fluxpumps Part 1: Realized methods for pumping flux

The magnetic and electrical properties of superconductors were a challenge for many inventors and designers to use superconducting materials in the construction of fully superconducting voltage and current sources commonly called fluxpumps. In the past twenty years a large variety of mechanically or electrically driven devices have been proposed and successfully operated.\ud \ud In this review the basic principle of operation of each class of devices is shown and specific material problems and limitations are reported. The review will be published in two parts.\ud \ud Part 1 deals with mechanical devices such as flux compressors and dynamos. Although those devices must have been of great importance for technical application, their construction and operation offered great experience with regard to the properties of superconducting materials, their joint techniques switching and mechanical and magnetic stability under ac and dc conditions.\ud \ud In this part also a start is made with the more promising class of electrically driven rectifier fluxpumps. With these rectifiers, current levels over 10 kA can be obtained with high efficiency

Methods of reducing energy consumption of the oxidant supply system for MHD/steam power plants

An in-depth study was conducted to identify possible improvements to the oxidant supply system for combined cycle MHD power plants which would lead to higher thermal efficiency and reduction in the cost of electricity, COE. Results showed that the oxidant system energy consumption could be minimized when the process was designed to deliver a product O2 concentration of 70 mole percent. The study also led to the development of a new air separation process, referred to as liquid pumping and internal compression. MHD system performance calculations show that the new process would permit an increase in plant thermal efficiency of 0.6 percent while allowing more favorable tradeoffs between magnetic energy and oxidant system capacity requirements