Coil misalignment compensation algorithm for single-stage inductive wireless power transfer system using model-based approach

Abstract

This paper presents a coil misalignment compensation algorithm based on a model-based approach for single-stage inductive wireless power transfer (IWPT) system. The single-stage IWPT system is low cost and highly efficient for small power applications, but it has a voltage envelope aligned with the line frequency. Therefore, the control period is also aligned to the line frequency (50–60 Hz), so the control dynamic is very slow. A linear voltage gain model is proposed to compensate the misalignment fast and efficiently based on a relationship between the coupling coefficient and the output voltage. Using the proposed model, the coil misalignment can be compensated within a single line voltage period. The proposed compensation algorithm is fast and straightforward, and it needs only a few additional devices compared with other methods. Also, the error of the proposed linear model occurred by the model approximation will be discussed quantitively. The proposed algorithm is analyzed including the model derivation and verified by experimental results using a 500 W IWPT prototype system.