Electromagnetic compatibility in power inverter design

Power inverter systems generate significant electromagnetic emissions. Methods were studied to model these systems and to reduce their emissions. Three topics are presented in this dissertation. Methods were developed to obtain simple SPICE models for complex systems which relate circuit components to physical geometry within the system. These models were derived using measurements or using partial element equivalent circuit (PEEC) and model size reduction techniques developed in this dissertation. Methods were proposed for developing a measurement-based model and were applied to a real power inverter/motor system. The model was used to identify system geometries responsible for critical resonances and to guide development of emission reduction strategies. A method was also proposed for developing a simple SPICE circuit by collapsing the many elements in a PEEC model into a reasonable number of elements which can still be related directly to the physical geometry responsible for the parasitics. This method was validated on realistic interconnects used in power electronics based on the frequency-dependent behavior of port impedances. Methods were also developed to predict the effects of ferrite chokes on the common-mode impedance and common-mode current of an active power systems when the ferrite is placed on the power cables. A high frequency analytical ferrite choke model was developed. Active common-mode loop impedance is found using the dual current clamp technique. The effectiveness of the approach was demonstrated on a real, active power/inverter system. --Abstract, page iv