Radiated Emissions of an Electric Drive System Estimated on a Bench Using Disturbance Currents and Transfer Functions

Electric drive systems are going to be the future of the automotive industry. Electromagnetic compatibility (EMC) issues and challenges arise with its growing entry into modern cars. This contribution provides an overview of the field dominating disturbance currents of an automotive high-voltage (HV) power inverter within an electric drive system. In order to minimize the cost and time needed for EMC measurements and engineering, a precompliance measurement method is introduced and applied to the inverter´s setup. The method presented allows the calculation of radiated emissions, according to CISPR 25, needed during the development process without the need for an expensive anechoic chamber. Transfer functions in combination with measured disturbance currents on the attached HV harnesses are used to obtain a cost-efficient estimation of the radiated emissions occurring during a component test. Its theory is discussed and demonstrated using a derived model. The method is verified using a rudimentary test setup, which represents a distributed system, and is later validated by the active electric drive system test setup introduced. Examinations of repeatability and reproducibility of disturbance current measurements as well as applied EMC counter measures complete the contribution.