EMC Design Techniques For The Digital Controller In Power Converters

As an important development trend in power electronics, electromagnetic compatibility (EMC) has received more and more attention recent years and much works have been done on the conducted EMI in the power converter. However, less attention has been focused on the EMC design techniques for the digital controller which is widely used in the power electronic systems. Therefore, both the conducted and the radiated EMC design techniques for the digital controller in the power electronic systems are investigated in this dissertation based on the advanced techniques developed in the EMC research area and the research achievements from our research group. The EMC trouble-shooting techniques based on the near field probes are presented at the last part of the dissertation.Some digital control controller related EMC Compliance tests are reviewed firstly. Then, the conducted EMI sources in the power converter and their characteristics are presented, the spread paths are analyzed, and the suppressed methods are derived. The methods to improve the conducted immunity level of the digital-controller are such as filtering, decoupling and isolating. Especially, the decoupling means of the power supply bus in the digital controller are examined and the effects on the EMC performance improvement are studied.The existing radiation interference models are not always verified by our experimental results. Therefore, both the low-frequency and the high-frequency radiated model are deduced and verified by our experiments. Based on those models, some methods such as address-signal-frequency-reduction and common mode (CM) signal reduction techniques are derived. Their effects are examined by the experiments.The radiated electromagnetic susceptibility (EMS) and the near field coupling problems in the power converter are the most difficult problems for the EMC engineers. Based on the EMS models of the digital controller, the near field coupling model in the digital controller and the modeling method with the help of numerical calculation are proposed in this dissertation. The validity is verified by the experimental results. The methods to improve the radiated EMS level of the digital controller in the power converter are then summarized.As a remedy for the EMC engineer, the EMC trouble-shooting techniques based on the near field probes are proposed in the last part of the dissertation. They can help us to orientate and characterize the EMI sources in the power converter. They are very helpful for the EMC engineer to solve some potential EMC problem.