Conceptual design of the power supply system for the in-vessel saddle coils for MHD control in ASDEX Upgrade

In the frame of an ASDEX Upgrade enhancement, a system of active in-vessel coils (of two types, dubbed "A" and "B") and conducting wall for MagnetoHydroDynamic (MHD) stabilization is being designed and implemented. The conceptual design of the power supply (PS) system has been worked out and extensive analyses have been performed to verify that the identified basic modules, based on a cascade topology with two IGBT (Isolated Gate Bipolar Transistor) H-bridges in series for the A units and one H-bridge for the B ones, were able to fulfil all the requirements, well within semiconductors safety operating limits. The paper summarizes the work which led to the definition of the PS requirements, describes the topologies of the selected basic units and of the overall scheme, discusses the design choices and reports the results of the numerical simulations carried out to check the overall performance.