Primary-Side Linear Control for Constant Current/Voltage Charging of the Wireless Power Transfer System Based on the LCC-N Compensation Topology

This article proposes a primary-side linear control strategy to realize the constant current (CC)/voltage (CV) charging for the wireless power transfer system, based on the
LCC-N
magnetic integration and non-compensation circuit. Different from the conventional compensation topology used in control strategies, this article combines magnetic integration structure on the primary side and noncompensation topology on the secondary side, which reduces the size of the additional compensation inductor and makes the secondary side more compact. Moreover, the primary-side linear control strategy is studied by using the improved load parameters identification method, based on the
LCC-N
topology. First, the
LCC-N
magnetic integration and noncompensation topology is introduced. An improved load parameters identification method considering the non-pure resistive input impedance characteristics of the rectifier is proposed to identify the current, voltage and equivalent resistance of the load, based on the
LCC-N
topology. In the process of identification, the complicated relationship between the input impedance of the rectifier and the load is needless. Then, according to the
LCC-N
output characteristics and identified load parameters, the relationship between the input voltage and load current and voltage is simplified to linear through the linear superposition of fundamental wave and third harmonic. And a linear control strategy on the primary side is proposed to achieve CC/CV output. Finally, a 1 kW WPT prototype is built to verify the effectiveness of the proposed control strategy. The experimental results show that the maximum error of the output current is 1.8% during the CC charging, and the maximum error of the output voltage is 1.2% during the CV charging.