Experimental results on pulse magnetic field coupling into PCB and its suppression with shielding box

Abstract

Due to the periodic switching operation of IGBT, there is a complex and high-intensity electromagnetic environment around the flexible DC converter valve. During this process, strong transit magnetic field caused by the turning on and off of large current can produce induced voltage on the nearby PCBs and even may affect the normal function of the PCBs. In this paper, the induced voltage in the output port on a PCB caused by a pulsed magnetic field is measured in laboratory. The effectiveness of a shielding box on suppressing the induced voltage and the magnetic field is also investigated experimentally. The results show that the induced voltage is about 12mV (in peak to peak value) for a 1.5kA/m, 6.4μs pulse magnetic field, and the shielding box has about 50dB time-domain shielding effectiveness.