Power stability analysis of three-phase omnidirectional wireless power transfer system based on tripolar pad

In traditional wireless power transfer (WPT) system, the output power and efficiency of the system decrease sharply when there is an angular misalignment between the transmitter and receiver. To solve this problem, this paper proposes an omnidirectional WPT system based on the tripolar pad to power up electronic devices, which can realize multiple degrees-of-freedom wireless charging. Firstly, the circuit model of the omnidirectional WPT system based on tripolar pad is established with LCC compensation network, the expression of output power is calculated, and the effect of cross-coupling between transmitting coils on the system is analyzed in detail. Through finite element analysis (FEA) simulation with ANSYS Maxwell, the expression of mutual inductance with rotation angle is fitted, which proves that the output power is independent of the rotation angle. Besides, it is found that the tripolar pad can generate a rotating magnetic field, which enables the receiving coil to pick up magnetic energy under an arbitrary angular misalignment. Then, considering the requirements of practical application, the design method of the proposed omnidirectional WPT system is given. Finally, a 100 W experimental prototype is set up to verify the effectiveness of the proposed WPT system. The output power fluctuation is within ± 8.7%, which verifies that the output power is independent of the rotation angle.