A 35 kA Disc-Shaped Thyristor DC Switch for Batteries Power Supply of Flat-Top Pulsed Magnetic Field

A 35 kA thyristor DC switch which consists of 8 paralleled high power thyristors installed in a disc-shaped aluminum bus to get a symmetrical structure is developed in order to meet the requirement of the DC power supply using lead-acid batteries in pulsed magnetic field with maximum flat-top current 35 kA, pulse width 1 s. This thyristor DC switch will be turned on at the beginning of experiment, and turned off by forced commutation technology which uses charged capacitors to output inverse current to extinguish the current of thyristor switch at the end. Every branch of 8 thyristors is in series with a stainless steel resistor 1.4 and a fast-fuse to achieve parallel current sharing and overload protection of the thyristors. The detail design of the thyristor switch is described and the validity of this design is proved by simulation using MATLAB R2008a in consideration of the actual parameters of pulsed magnet with crowbar. At present the manufacturing and assembling of the switch has been completed, and primary short pulse test is finished. Finally the DC switch will be used in two-coil or three-coil 40 T/0.5 s flat-top pulsed magnet for some special science experiments by the end of 2012.