Research Projects

Emissions from fossil fuel vehicles contribute to 24% of global CO₂ emissions, for which electric vehicles (EVs) are being promoted globally to reduce environmental damage. In India, the National Institute of Transforming India (NITI) initiated the Faster Adoption and Manufacture of EVs (FAME) scheme to promote eco-friendly mobility, allocating $135 million under FAME II for setting up 2,900 EV charging stations across 25 Indian states. In this context, DC fast charging of EVs can recharge up to 80% of battery capacity in just 20–30 minutes. The DC-DC converters used in fast charging systems serve to precisely step up or step down the high-voltage DC supply to match the battery’s voltage range, ensuring safe and efficient charging. The voltage levels used for EV charging are either 400V or 800V DC, with the latter facilitating faster charging. However, one potential concern is that the silicone rubber (SiR) insulation used in EV charging cables has a tendency to develop space charge under DC stress, which may jeopardize the life of the insulation. Space charge accumulation in EV charging cable insulation primarily originates from electron injection from the cathode and hole injection from the anode, as well as from the field-assisted ionization of impurities within the material. The presence of space charges distorts the electric field distribution, leading to partial discharges, which can trigger premature insulation breakdown. The homo-charges intensify internal bulk fields, while the hetero-charges increase the field near the electrodes, both potentially compromising the microstructure of the polymeric insulation and posing serious reliability threats to cable insulation. Besides, the addition of nanoparticles like hexagonal boron nitride (h-BN) composites has been found to improve the thermal as well as electrical properties of SiR cable insulation for application in EVs. However, to date, limited research work has been done to detect the space charge in EV charging cables due to transient (on and off) DC stress. Considering the aforesaid facts, the main aim of this research project is to investigate the space charge development in SiR insulation and its nanocomposites under DC stress using the pulsed electro-acoustic (PEA) method under altering electric fields and at different temperatures. To this end, SiR-based insulation with different h-BN nanofiller percentages will be prepared. Following this, PEA method-based space charge measurement will be performed at different temperatures and different electric fields to investigate the space charge development due to cyclic on-and-off DC stress. Further, an automated space charge detection software model for accurate identification of the type of space charge accumulation will be developed. Finally, using the data available, a machine learning model will be trained for prediction of space charge development in SiR nanocomposite insulation for EV charging cables.

Charging cable, electric vehicle, silicone rubber, space charge, machine learning, and insulation