Power Line Impedance Characterization of Automotive Loads at the Power Line Communication Frequency Range

A complete system able to measure complex impedance, both in magnitude and phase, of an automotive electrical load is designed. The development of such system emerged from the need of measure the impedance of these loads in a wide range of frequencies (100 kHz to 30 MHz) while being connected to power supply and in operation. This powered up condition introduces several problems when the impedance is measured by means of traditional instruments such as Vector Network Analyzers (VNA), which could be damaged by transients. Understanding the behaviour of electrical cars loads in the frequency domain is of primary importance not only for in-vehicle Power Line Communication (PLC) channels response, but also to understand electromagnetic emissions (EMI) problems related with this type of communications.