Patent RU-2325732-C1 (RU)
Title: Method and system of superconducting magnet powering to frozen-in field mode
Inventor: RICHNJAK ALEKSANDR MIKHAJLOVIC
IPC: H01L39/16
Filed: 2007-04-17
Granted: 2008-05-27
Abstract: FIELD: transportation. 
     SUBSTANCE: invention is mainly related to transport electric power engineering and designed for powering superconducting magnet (SM) to frozen-in flux mode, mainly in order to create magnetic levitation and driving and stabilizing forces of high speed transport together with electric magnets of rail trucks. It is also designed to power SMs in geomagnetic torque motor to orientate and stabilize space crafts and electrophysical instrumentation. SM powering system includes: energized SM with winding from high-temperature superconductor (HTSC) inserted into cryostat; superconducting bypass with primary two-circuit winding from HPSC and thermal control winding of superconducting bypass are also inserted into cryostat; cryo refrigerator (CR); SM feed current meter; SM powering subsystem itself including adjustable frequency inverter with transformer output. Transformer input is linked with power supply buses. Three transformer outputs form the beginning, end and lead-out from the middle point of secondary transformer winding. SM powering subsystem also includes single-cycle two-phase rectifier based on two diode gates. Gates anodes are connected to the beginning and end of secondary transformer winding. Their cathodes are attached to the one of SM winding leads; the other lead is coupled with lead-out from the middle point of secondary transformer winding. Both SM winding leads are linked with primary winding of superconducting bypass by means of HPSC wires enclosed into heat-insulated connecting pipes with wire cooling channels. Power subsystem of thermal control superconducting bypass winding with outputs connected to thermal control winding leads via controllable turn-off switch is also available in the subsystem as well as threshold detector, current meter in primary superconducting bypass winding and powering system control unit. According to the invented method, each SM with superconducting bypass cool cryo refrigerator until stable superconducting state and supply current to thermal control winding. Primary winding of superconducting bypass is then transferred to resistive state by heating to the temperature higher than critical HPSC temperature. Adjustable frequency inverter is switched to maximum invariable frequency and transformer is switched to output voltage for the period until SM powering with invariable nominal power will start. From this moment frequency is decreased which means that output transformer voltage will be also decreased based on analytical dependences on powering time which are specified in invention description and formulas. Analytical dependencies correspond to SM powering mode with invariable nominal power. When SM powering current will achieve the required maximum value I sm , superconducting bypass of thermal control winding is de-energized and cryo refrigerator is switched on to operate in augmented rating mode. Output transformer voltage and frequency are abruptly decreased to their nominal values to be maintained constant during cooling time of primary superconducting bypass winding to the temperature below critical HPSC temperature. At the moment of primary superconducting bypass re-transition to superconducting state, current I sm  is short-circuited via superconducting bypass; adjustable frequency inverter is switched off while cryo refrigerator is transferred to the nominal mode of operation. 
     EFFECT: decrease of weight; decrease of power supply cost and power in superconducting magnets powering system in frozen-in flux mode. 
     2 cl, 4 dwg, 1 tbl