Accurate first-harmonic-approximation-based model of the diode rectifier in series-series compensated inductive wireless power transfer link at load-independent-voltage-output frequency

Abstract

The brief proposes a modification of classical pure resistive first harmonic approximation (FHA) based equivalent of diode rectifier in series-series compensated inductive wireless power transfer link (SS-IWPTL), operating at load-independent-voltage-output (LIVO) frequency. It is shown by means of time-domain analysis that a load-independent inductance should be added in parallel with the typically utilized load-dependent resistance to accurately represent input rectifier impedance at operating frequency. It is also shown that the worst case (minimal) inductance value is obtained when equivalent series resistances (ESRs) are ignored. In practical systems, non-zero ESRs are typically present and are typically desired to be as low as possible to increase the power transfer efficiency. It is shown that increasing the ESRs leads to escalation of equivalent resistance and inductance values (i.e. reducing the influence of the latter), without altering the load-independence characteristics of equivalent inductance. Simulations and experiments based on a 400 V, 1 kW strongly-coupled SS-IWPTL operating at LIVO frequency validate the proposed analysis.