Experimental validation of onboard electric vehicle chargers to improve the efficiency of smart charging operation

Electric vehicles (EVs) are at the center of the power and transport sector coupling; however, smart charging is required to not compromise the integrity of the grid. In this work, we propose, test, and validate a method for investigating EV onboard chargers via the OBDII port. We present the charging efficiency and reactive power characteristics of 38 different EV models from the last 11 years. Data show that, due to added losses, smart charging through current modulation can increase global charging energy demand from 1%-10%. In addition, EVs consume a relatively large amount of reactive power at lower currents, and some models violate the power factor limits for the low-voltage grid. Our projections show an efficiency of 88%-95% by 2030 and a saturation between 90%-96% by 2035. Therefore, the newly presented AC-to-DC conversion efficiency values help achieve better results when calculating life cycle assessment, grid integration and energy simulation that consider EVs. Curtailed smart charging can further integrate charging needs by implementing phase balancing and matching with behind-the-meter local generation. Finally, our results urge regulators and automakers to further improve charging technology and legislation based on other technological experiences, e.g. solar inverters.

Automated summary

In this study, the researchers propose, test, and validate a method for investigating EV onboard chargers via the OBDII port. They present the charging efficiency and reactive power characteristics of 38 different EV models and find that smart charging through current modulation can increase global charging energy demand. They also observe that some EV models violate power factor limits for the low-voltage grid. The projections show an improvement in charging efficiency by 2030 and saturation by 2035. The results highlight the importance of improving charging technology and legislation based on other technological experiences.