Automotive power electronic future - from an EMC perspective

One way to lower the fuel consumption in future vehicles is to replace mechanically driven systems by electrical. The drawback with this solution is the increasing number of electrical loads, which creates more electromagnetic emissions that could disturb the surrounding environment. Many of the electrically driven loads are controlled by pulse width modulation, which could be a source of electromagnetic interference. In this paper, different solutions are tested with the intention to decrease the disturbances from a pulse width modulated system. The proposed methods do not require any extra components or costs, and implies altering the switching frequency and the frequency content of the voltage pulses from the system. It is shown that both a randomly varying switching frequency and an increase in rise and fall times for the voltage pulses are feasible ways to decrease the conducted emissions from a pulse width modulated system