To scale up the capacity of a SMES for a practical application, it should be necessary to adopt a high voltage system, a large current system or a module type system. The first system is difficult because of the very low withstanding voltage of a superconducting coil and second one also leads difficulties such as multiple connections of many units of convertors at dc side and large current conductors of superconducting coil. The third system which is composed of some numbers of modules with small scale convertor units and element coils might be a solution of above difficulties. In this module type system, module coils have magnetic linkage one another.
In this paper, the influence of magnetic linkage between coils of a module type SMES are investigated by computer simulation. The magnetic linkage is different with numbers of modules and connection method of coils. By the effect of this magnetic linkage, each module coil current is different at same power of each module convertor. The transfer characteristcs of current and energy are shown for discharge from one or some modules of 6 modules consisted of 18 coils. Discussions are made on the situation of existing an unused module at the quench. And the transfer with same current of each module is shown by control of convertor power of the current feedback.