Analyzing phase imbalance in smart charging of multiple EVs: an experimental approach

The increasing penetration of electric vehicles (EVs) is causing uneven loading in low voltage distribution networks, primarily due to variations in smart charging rates and simultaneous charging of single-phase and three-phase EVs. This study experimentally analyzes three mainstream EVs (Renault Zoe R90, Peugeot e-2008, Nissan Leaf e+) charging concurrently, with the Zoe and e-2008 using three-phase power and the Leaf using single-phase power. Smart charging capabilities are used to gradually increase charging current from minimum to maximum power for each vehicle. Harmonic, current, and voltage measurements were taken at the point of common coupling using a power quality harmonic analyzer. The results reveal significant harmonic imbalances in three-phase networks, particularly when different types of EVs are charged simultaneously. This highlights the necessity for active load management to ensure EV charging adheres to industry standards and recommendations, such as IEC 61000-3-12 for harmonic emissions and CIGRE C4.07. Such active management strategies can mitigate the negative impacts of uneven loading and ensure the stability and reliability of power distribution networks as EV adoption continues to grow.