Principle of Torque Compensation Machines. Examples of Three-Windings Machines.

With equal capacities, the electric machines are the smaller, the higher is the induction, so that the leading manufacturers study the use of superconductors allowing very high inductions. Machine designs operating at 3 T and even at 6 T are known but in the present state of technology, wire remains superconducting only in the presence of continuous or slowly variable magnetic fields which leads to separate the superconducting winding which generates the induction flux from the other windings which transmit mechanical torques and electromagnetic energy exchange currents. Structures of the machines developed by Renard and Mailfert fully isolate the field winding from torque or current interferences and, furthermore, considerably improve the thermal balance. A detailed description of the operation of the three-winding-type cryogenic motors and generators is given as well as that of the linear motors and transformers operating along the same principles.