Sammendrag
The characteristics of inductive power transfer (IPT)
systems are sensitive to the variation of the coupling coefficient
caused by misalignment conditions or different gaps. This results
in a reduction in transferred power and efficiency. The output
characteristics considering frequency modulation applied in SS,
LCC-S, and LCC-LCC compensated IPT systems have been
explored, revealing that high order compensation topologies hold
limited power regulation ability if coupling varies significantly.
The parameter sensitivity of LCC-LCC compensated topology is
investigated through the Singular Values (SVs) analysis. It is found
that the variation of the parallel compensated capacitors have the
greatest impact on the output power. Aiming at alleviating the
power drop caused by the coupling variation, a parameter offline
tuning method realized by switching the parallel compensated
capacitance for a detuned LCC-LCC resonant converter is
proposed for EV wireless charging. Analytical expressions have
been derived in aiding the design of modified value of capacitance
ensuring primary Zero Voltage Switching (ZVS) operation. Thus,
the detuned parameter combinations, which deliver rated power
even with the worst coupling, are obtained. Finally, a 6.6 kw
prototype has been built to verify the validity of the proposed
topology, which can deliver 6.1 kW with an efficiency of 94% even
when the coupling drops from 0.3 to 0.15.
Index Terms—anti-misalignment, detuned resonant tank, LCC-LCC compensation, Electric Vehicle (EV), frequency tuning
method.
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