Measurement-based Harmonic Analysis of Electric Vehicle Smart Charging

Smart charging of electric vehicles (EVs) is becoming a standard application for managing peak demand, deferring network reinforcements, and minimizing charging costs. While the existing literature primarily focuses on scheduling algorithms and strategies to improve voltage profiles, it has largely overlooked the investigation of harmonic emissions. This paper presents, for the first time, high-quality data on harmonic emission profiling of smart charging applied to three different mainstream EVs using both three- and single-phase AC charging. In each case, the charging current was decreased from the maximum allowed charging rate (32 or 16 A) to the minimum charging rate (6 A) in 1 A decrements. The collected data were subsequently analyzed and both total harmonic distortion (THD) and individual harmonic orders were compared against industry standards. The results indicate a significant increase in harmonic content as the charging current decreases for all vehicles and charging types. Case studies involving multiple EV charging scenarios are conducted, revealing that harmonic content could serve as a limiting factor in multiple EV charging situations, in addition to existing limitations such as line capacity and transformer headroom.