Design and optimization of I-shape anti-offset coils structure for
dynamic wireless power transfer systems in smart rail train
Abstract
In dynamic wireless power transfer systems for smart rail
trains, a high fluctuation rate of mutual inductance leads to reduced
efficiency when an offset occurs between the transmitting and receiving
coils. This paper explores the mutual inductance characteristics and the
variation rule of magnetic induction strength between the transmitting
coil and the receiving coil at offset. And proposes an I-shape coil
structure. The I-shape coil structure has good anti-offset performance
in the direction of motion, and the maximum offset distance is up to 1.2
times the outer length of the transmitting coil. First, the mutual
inductance characteristics of this I-shape coil structure are
investigated based on the coupling mechanism of the I-coil. Meanwhile, a
mutual inductance optimization method is proposed, which is used to
obtain the values of each coil parameter that satisfy the requirements.
Secondly, the magnetic core optimization of the I-coil structure has
been carried out to achieve higher mutual inductance and better
transmission efficiency. Finally, a wireless power transfer system is
constructed based on the obtained coil and magnetic core parameters.
Simulation and experimental tests are carried out for this coil
structure and the coil structure with magnetic core, respectively. The
experimental results verify the rationality and correctness of the
structure. The results show that the maximum mutual inductance
fluctuation rate is only 4.97% in the coil structure without magnetic
cores with the offset distance between the transmitting and receiving
coils at 120% of the outer edge length of the transmitting coil. With
the addition of the magnetic core, the maximum mutual inductance
fluctuation is only 5.02% with an efficiency of 97.61% at an offset
distance between the transmitting and receiving coils of 120% (50.8 cm)
of the outer edge length of the transmitting coil.
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