Sizing DC Link Filter Capacitors in Complex Electric Powertrains∗

Power electronic devices in electric vehicles can cause significant voltage harmonics on the drive train's DC-link. Filtering of such harmonics is most essential in order to guarantee sufficient quality of the main supply voltage and thus proper operation of all components. However, appropriate sizing of filters requires a detailed model of the powertrain which is especially challenging for complex high voltage architectures with two or more power sources. In this work, dynamic powertrain models are derived with a focus on low frequency harmonics up to several kHz. The impact of simplified models as well as control of the DC-DC converter on the filter requirements is discussed in detail by the example of a hybrid fuel cell vehicle.