High-Performance Harmonic Filter Design for Electric Vehicle Charging Stations to Enhance Power Quality

The growing EV charging infrastructure introduces significant power quality issues due to harmonics from nonlinear loads like diode rectifiers and switching converters. These harmonics increase current/voltage THD, degrade power factor, voltage regulation, and system efficiency, often violating the IEEE 519 standard. This paper presents a comprehensive design and critical analysis of four passive harmonic filter topologies, namely, single-tuned filter (STF), double-tuned filter (DTF), high-pass filter (HPF), and C-type high-pass filter (CHPF), to mitigate harmonics and improve power quality in grid-tied EV charging stations. A generalized model is developed and simulated in MATLAB/Simulink R2021a for an EV charging load, with all filters evaluated under identical conditions based on current THD (I-THD), voltage THD (V-THD), input power factor (PF), voltage regulation (VR), and efficiency. The results indicate that the STF achieves an I-THD of 8.3%, V-THD of 4.6%, PF of 0.92, VR of 6.2%, and an efficiency of 91.3%. The DTF performs slightly better, with an I-THD of 6.1%, V-THD of 3.9%, PF of 0.95, VR of 5.4%, and efficiency of 93.5%. The HPF further improves these metrics, showing an I-THD of 5.6%, V-THD of 3.5%, PF of 0.96, VR of 5.0%, and efficiency of 94.2%. In comparison, the proposed CHPF outperforms all traditional filters, achieving the lowest I-THD and V-THD values of 3.7% and 2.1%, respectively, the highest PF of 0.987, improved VR of 3.8%, and superior efficiency of 96.2%. The results confirm that CHPF offers superior harmonic mitigation, voltage stability, power factor, and efficiency, thereby ensuring better vehicle-grid compatibility.