Impedance Analysis and Compensation Method for IPT System Applying Inverse Coupled Current Doubler Rectifier

Inverse coupled current doubler rectifier (ICCDR) has been employed in inductive power transfer systems because of high current gain and conversion efficiency. Due to the reliable approximations, fundamental harmonic analysis (FHA) can be adopted for studying ICCDR under continuous conduction mode (CCM). However, due to the influence of the transformer windings, ICCDR is more prone to discontinuous conduction mode than diode full-bridge rectifier when cascaded with an LCC topology. In such scenarios, FHA becomes ineffective, as the equivalent impedance calculated by FHA gets inaccurate, leading to compromised overall resonance. This article presents an innovative approach by utilizing the critical state current characteristics of rectifier diode to derive the boundary conditions for CCM, which establishes a parameter criterion to ensure ICCDR operates in CCM. To uncover the root cause of poor constant current effect within a relatively wide load range, an accurate resistive-inductive input impedance model of ICCDR is derived through FHA with the premise of CCM. Furthermore, a novel compensation scheme is introduced to optimize the constant current output effect and achieve zero phase angle, verified on a prototype with 20-A current output and maximum 1.66-kW power output. The proposed LCC–LCC compensated IPT system demonstrates ±2% output current variation across an 8:1 load resistance range.