BLDC motor and drive conducted RFI simulation for automotive applications

In considering automotive conducted radio-frequency-interference (RFI) specifications applicable to motors and their associated drives, simulation of conducted RF emissions in the range from 150 kHz to 30 MHz is an area of interest from the product design perspective for several reasons. Traditionally, suppression of conducted noise in this frequency range of interest has been achieved through the use of bulk suppression elements such as capacitors and inductors. These elements consume valuable space within the motor, as well as add cost. The selection of bulk noise suppression elements, has, in the past, been predominately made through trial and error "brute force" methods. A method is presented whereby conducted RFI emissions can be simulated through the use of a high-fidelity virtual motor and drive model, as well as a virtual spectrum analyzer. Experimental validation of the model shows that accurate predictions can be made in the low-frequency range, below 10 MHz. Suggestions are made on how to improve the model at higher frequencies.