Stray Magnetic Field Analysis of ITER Poloidal Field Converter Unit

Due to the space limitation and safety concerns, the non-same-phase anti-parallel connection structure is applied in the International Thermonuclear Experimental Reactor (ITER) Poloidal Field (PF) converter unit. Consequently, the electromagnetic interference caused by the strong stray magnetic field has been one of the main concerns in its design. And this paper mainly presents the stray magnetic field analysis of ITER PF converter unit. At first, an isolated phase bus (IPB) is designed for the shielding of the alternating magnetic field generated by the ac busbars to avoid overheating on ferromagnetic materials in the fire wall. The stray magnetic field on the fire wall is analyzed to verify the shielding effectiveness of the IPB. Then, the stray magnetic field generated by the converter bridges and dc reactors which is very hard to be shielded is analyzed separately. The results show that the stray magnetic field exceeds the limit value and will be a potential threat for the instrument and control (I&C) system. All the analysis presented in this paper will provide useful inputs for the electromagnetic compatibility design and test of the I&C system.