Analysis and Experiment of Battery Bank Power Supply System for Long Pulse Helical Magnet in WHMFC

Traditionally, pulse capacitor and pulse generator power supply are frequently used to energize pulse high magnet up to 100 T, but they are not the ideal power supply for long pulse and low ripple high magnetic field so that they cannot meet higher requirement of science research and wider application in industry. In Wuhan National High Magnetic Field Center (WHMFC), a new type power supply system which uses lead-acid batteries has been developed to output more energy and longer pulse than capacitor bank, and also output more steady voltage and smaller current ripple than pulse generator using ac/dc convertor. The battery power supply is a new application that valve-regulated lead-acid battery (VRLA) is used in high-rate discharge with pulse current 2 kA/2 s or peak 2.5 kA/1 s, and it is not unnecessary to analyze the changes of internal resistance and main factors which influence the battery life under the high current discharge. Based on the simulation analysis of the battery bank system, the structure and parameters including charge and discharge circuit of battery bank which can output maximum 35 kA/1 s under 770 V are designed. The tests of battery bank discharge, current sharing among the 15 parallel branches, and experiment of the helical magnet 32 T/1.5 s as battery bank outputs 34.5 kA/0.8 s are presented.