17-10-2016, 11:56 AM
i am really interested in this topic
i want to study this topic in more depth
i am doing electrical engineering
i may have a seminar on it too
Posts: 6,843
Threads: 4
Joined: Mar 2015
Superconducting electric machines are electromechanical systems that rely on the use of one or more superconducting elements. Since superconductors have no DC resistance, they typically have greater efficiency. The most important parameter that is of utmost interest in superconducting machine is the generation of a very high magnetic field that is not possible in a conventional machine. This leads to a substantial decrease in the motor volume; which means a great increase in the power density. However, since superconductors only have zero resistance under a certain superconducting transition temperature, Tc that is hundreds of degrees lower than room temperature, cryogenics are required.
Now there is more interest in superconducting AC synchronous electric machines (alternators and synchronous motors). The direct current electromagnet field winding on the rotor (rotating member) use superconductors but the alternating current multiphase winding set on the stator (stationary members), which have no practical support by superconductors, uses conventional, normal conduction copper conductors. Often the stator conductors are cooled to reduce, but not eliminate, their resistive losses.
Abstract
With respect to the electric power industry, the superconducting AC generator has the greatest potential for large-scale commercial application of superconductivity. Such a machine should be able to convert mechanical energy to electric energy more efficiently and with greater economy of weight and volume than any other method. These advantages can be accrued at a scale of 1200 MVA output, with the added potential of operation at transmission line voltage and greater system stability. In the past, a great deal of R&D was done in this area, but the present industry trend to smaller machines has decreased this effort. Though the advantages diminish at the much smaller scale of 250 MVA, such machines still offer interesting possibilities. Superconducting synchronous generators with a superconducting adjustable field rotor keep power losses to a minimum since the field in the stator is phase-locked in synchronism with the rotating rotor field. The high magnetic flux density produced by a superconducting rotor field winding permits a great reduction in the amount of iron required in both the rotor and stator. This reduction introduces degrees of freedom not previously possible in generator or motor design. This article is written to help better perceive the technological potential of new developments
Superconducting elements are the most important part of electromechanical systems because of their functioning and these systems form the superconducting electric machines. Lack of DC resistance in super conductors contributes much to its greater efficiency.
In a super conducting machine very high magnetic field is produced otherwise impossible in a conventional machine and is the main characteristic of super conductors. High magnetic field results in lesser motor volume and ultimately more power density.
Cryogenics are highly used in super conductors to maintain a specific temperature which is less than the room temperature upto hundred degrees, super conducting transition temperature (Tc), at which the superconductors reach the zero resistance.
Super Conducting Generators 1
Superconducting AC synchronous electric machines which include alternators and synchronous motors have become more common nowadays than before.
The rotor or the rotating member of the machines has an electromagnetic field winding on itself for direct current which employs superconductors.
The stationary member or stator of the machines however utilizes the same old conductors constituting of copper conductors which undergo normal conduction.
An attempt to reduce the resistive loss of the stator conductors they are cooled but the loss is not permanently removed.