A Passive Current Sharing Method for Multitransmitter Inductive Power Transfer Systems

A multitransmitter (multi-TX) inductive power transfer system would not only offer better spatial freedom but also improve the overall output capability. Under heavy-load condition, it is desirable to fully utilize the output power capability, and the overall input power needs to be balanced among the multiple TXs. This article proposes a simple and low-cost current sharing method to balance the input power. The current distribution is analytically studied for an example two-TX system, and the sharing path is proposed to balance the power under coupling variation and coil inductance mismatch. It also explores the influence of sharing path on the efficiency and zero-phase operation. Besides, the proposed method is valid for other compensations and can be extended for
N
-TX (
N
$>$
2) systems. Finally, a two-TX system is implemented to verify the sharing effect. The current imbalance factor is effectively reduced from 37% to 2.7% under the worst coupling cases.