EMI Analysis On TCU Controller

With the application and development of electronic technology, especially power electronics, EMI (Electromagnetic Interference) issues of electric circuits become more and more serious, especially application of fast semiconduct switching devices such as IGBT, MOSFET etc, which would produce HF pulses, then followed by large dv/dt and di/dt, and they are the essencial EMI sources. And may produce large EMI from several kilo to several million hertz frequency and the electromagnetic compatibility (EMC) standard is not submitted.HF characteristics of passive components are analysed in this thesis. Based on the analysis on HFcharacteristics of such passive components as resisters, inductors and capacitors, we may see that, practical resisters have stray inductances; inductors couldn't filter HF noises efficiently because of distributing capacitor between circles or layers; there are many kinds of capacitors, they are used in different situations according to their HF characteristics: electrolytical capacitors are fit for minishing ripples in rectify-circuits as a result of their large capacity, while HF ones are suitable for filtering HF noises due to their nice HF characteristics. What's more, in order to reduce HF parasitical parameters, we should make sure down-leads of capacitors are as short as possible while in practical circuits. Besides, leads have some HF parasitical inductance and capacitance. Consequently, we must choose passive components carefully.The mechanism of EMI is explained, based on analysis about working procedure of power electric circuits, especially about characteristics of power switching devices, different methods should be taken out to restrain or decrease EMI. And the following are primary solutions to restrain EMI, such as grounding, shielding, filtering, and PCB design etc. One or combination of them may be applied on the basis of different situations.EMI issues on driving parts and powers sections of TCU (Transmission Control Unit) controller are analyzed in detail. Interference waveforms were collected by means of experiments, then some solutions on rejecting electromagnetic interference are proposed, Evenmore, experiments had done to verify their correctness and rationality on aspects of both time-domain and frequency-domain.