A new method to control EMI noises generated in power converters

The structure of power converters with a rectifier and an inverter is studied through simulations using the TLM (transmission-line modeling) method. The structure has the ability to prevent EMI noises from diffusing in noise sources. First, analyses regarding frequencies with EMI noises occurring by switching operations are performed using circuit parameters of an intelligent power module (IPM) composed of the power converters, which were previously measured, and then obtained results are verified by experiments. Processes in which the noise with the verified frequency diffuses into power transmission lines formed by power converters are analyzed by the EMI noise analyzing software (micro-strips) used the TLM method. On the basis of the analyzed results, structures of the power transmission lines suitable for attenuating EMI noises are proposed and these are applied to power converters formed using a multi-layer power printed board. One structure was chosen and compared with the conventional molded type one. The damping rate of the near magnetic fields was improved as much as 30 dB. Moreover, when the proposed power converter was equipped on electric vehicles (EVs), influence which the near-magnetic fields has on an approaching car was investigated in comparison with radiated EMI noises between electric vehicles (EVs) with the proposed and conventional power converters. As a result, it was proved through simulations that EVs with little electromagnetic interference would be realizable by applying the proposed structure.