Characteristics of AC grounding in an automotive ECU

This paper investigates alternating current (AC) grounding as a cost-effective technique for reducing radiated emissions from an automotive electronic component or system. AC grounding is a technique that provides an electronic control unit (ECU) in the vehicle with a good ground path for radio frequencies (RF), while preventing the power current from returning through the chassis. This paper provides a technique for determining the optimum configuration of an AC ground network, including component values. The experience here is focused around the analysis and reduction of electromagnetic interference (EMI) created by a pulse-width modulation (PWM) operated automotive power device.