A Single-Stage IPT Converter With Optimal Efficiency Tracking and Constant Voltage Output Against Dynamic Variations of Coupling and Load

Abstract

Multistage design based inductive-power-transfer (IPT) systems have been carried out to cope with power regulation and optimal efficiency tracking against variations of load conditions and coupling coefficients in dynamic scenarios like roadway-powered electric vehicles. However, it is still challenging for a single-stage IPT converter to do so, due to the fixed transfer ratio and narrow optimal load range of the resonant tank. This paper aims to fill the gap by integrating active switches within the IPT converter to extend the modulation range. A new series-series compensated IPT converter is proposed, which, unlike the conventional ones, employs two switched-controlled capacitors (SCCs) and a semi-active rectifier (SAR). The secondary SCC and the SAR cooperate via an inner control loop to emulate a null secondary impedance and an optimal load resistance, while the primary SCC is responsible for the output power regulation via an outer control loop. The operating principle enables a constant voltage output and optimal efficiency tracking against dynamic variations of coupling coefficient and load condition, while fixed operating frequency and soft switching are also permitted. Experimental results validate the performance.