An Accurate Online Parameter Estimation Technique for Inductive Electric Vehicle Charging Systems

Abstract

An accurate online parameter estimation method for inductive power transfer (IPT) systems is introduced. Using the proposed parameter estimation method both magnetic coupling factor and battery charging current can be estimated simultaneously. This method is specifically suitable for inductive electric vehicle (EV) charging systems in which the battery charging load dynamically varies during the charging process. The proposed method only requires measurements from the primary side and thereby eliminates the need for data communication between the transmitter and receiver. The technique is based on the use of resonance frequency tracking controllers that continuously match the switching frequency the resonance frequency of the IPT system. Detailed analytical formulations for the derivation of magnetic coupling factor and battery charging current and voltage are presented. Theoretical analysis, simulation models and experimental validations of the proposed parameter estimation method are presented. The results show that the proposed method can accurately estimate the magnetic coupling factor and battery charging current in real-time. The experimental results confirm that the proposed method can be easily implemented in any IPT system.