Contact Resistance Estimation of Electric Vehicle Charging Connector

The paper proposes a method to estimate the contact resistance inside the outlet between a charging cable and an electric vehicle. First, an electro-thermal model of some components close to the contact area inside the vehicle outlet (in the female part of the outlet) and of the harness inside the vehicle is proposed. The charging cable and the associated components are the male parts of the outlet. They are not modeled as these components can differ from a charging to another. They also depend on the mode and the charging infrastructure used. It is only supposed that the charging cable evacuates an unknown heat rate. A linear approximation of the electro-thermal model is then obtained and used to design a closed loop estimator of the total heat rate at the contact area. Using this information, a least square method is used to estimate the contact resistance that can be deduced from the first values of the total heat rate after a step variation of the current in the charging cable.