Self-Inductance Variation and Harmonic Current Effects on AGV Charging System

This paper focuses on the study of the tightly coupled inductive power transfer technology for charging automatic guided vehicles. It highlights how two factors, high-order harmonic currents and variation in self-inductance, affect the system’s efficiency. Due to the low clearance for the automated guided vehicle and the square-wave input voltage, both factors will exert a considerable influence. The presence of harmonics leads to additional power loss, while variations in self-inductance directly affect link efficiency by disrupting resonance conditions. Both factors contribute to a decrease in overall system efficiency. This paper offers an in-depth theoretical modeling of tightly coupled IPT systems, considering the LCC-LCC compensation circuit. It takes into consideration variations in self-inductance and the influence of harmonic currents while maintaining a constant operational frequency. Additionally, the integration of self-inductance variations into the system demonstrates their simultaneous impact on performance alongside harmonic currents. This paper includes finite element analysis (FEM) of the magnetic coupler to illustrate the design process. Furthermore, a simulation with a circular-shaped magnetic coupler, delivering 1.8 kW, is implemented.