Near-Field Electromagnetic Energy Flow Regulation Method for WPT System via Frequency Adjustment

A near-field wireless power transfer (WPT) system may simultaneously contain magnetic field coupled power (MFCP) and electric field coupled power (EFCP), and the comprehensive utilization of the two types of coupled power in space can help improve the power transfer capability and efficiency under misaligned conditions. This would help improve the grid interaction capabilities of electric equipment with near-field WPT systems to tackle the challenges posed by the integration of large-scale WPT systems to the power grid. From the electromagnetic energy flow theory based on the Poynting vector analysis, this article describes the energy flow process of the near-field WPT system under the effect of distributed parameters and obtains a reduced-order evaluation method to assess the transmission levels of the two types of coupled power. Extracting the characteristic parameters related to the coupling characteristics of the near-field WPT system, a method is proposed to regulate the near-field electromagnetic energy flow by adjusting the system’s working frequency. By actively regulating the transmission ratio of the two types of coupled power, the system can achieve optimal output characteristics under coupling misalignment. Simulations and experiments are carried out to verify the effectiveness of the proposed near-field electromagnetic energy flow regulation method. This article provides a new method to realize complementary output and ratio regulation of two types of coupled power using couplers made of simple materials.