Battery Parameter Identification Based on Wireless Power Transfer System With Rectifier Load

This article presents battery parameter identification methods considering a rectifier and battery load in wireless power transfer (WPT) systems. In order to reduce the cost and complexity brought by the wireless communication, the load parameters are usually identified through WPT primary side measurement to control the system. Compared with the conventional methods, battery state estimation and load parameter identification are achieved in this article based on only one measured WPT primary side variable. First, the WPT equivalent load is quantitatively expressed, which contains both resistance and inductance components. Then, identification methods for the battery voltage and equivalent resistance are proposed. Meanwhile, selection criteria for the primary side variables are studied to achieve a simple process and high accuracy. Furthermore, a WPT prototype is developed, and the experimental results prove the effectiveness of the equivalent load analysis and the proposed identification methods under the conditions of both battery voltage change and phase shift angle variation. Additionally, the robustness of the proposed methods is studied, considering compensation parameter changes and coil misalignment. Finally, the proposed methods are applied to battery state-of-charge estimation, and the results suggest that the battery power shortage and full charge states can be estimated with high accuracy.