Comparison of Tripolar and Circular Pads for IPT Charging Systems

Recently, a magnetic pad called the tripolar pad (TPP) has been introduced for inductive power transfer (IPT) systems. This paper evaluates the effective coupling factor and leakage magnetic field of a 20-kW IPT system that uses a combination of TPP and circular pad (CP) topologies over a range of lateral displacements. The results show that the effective coupling factor and the leakage magnetic field of the TPP-TPP system are substantially better when the secondary is displaced away from ideal alignment. Leakage magnetic field is reduced up to 43% compared to the CP-CP system at the worst-case misalignment, which is due to the ability of the TPP-TPP system to generate and capture different types of magnetic field shapes. Simulation methods for both the TPP and CP are validated in the laboratory using a 2-kW system operating at 85 kHz.