A 2-D Magnetic-Field-Orientated WPT System With Enhanced Misalignment Tolerance and Reduced EMF Emission

Lateral misalignment tolerance is a crucial figure of merit for wireless power transfer (WPT) applications. In this paper, a WPT system with an exciter-tripolar-repeaters (ETR) transmitter pad is proposed for enhanced two-dimensional (2-D) misalignment tolerance and reduced magnetic flux leakage. The transmitter pad consists of a centrally placed exciter coil and three larger quadrature repeater coils arranged as a planar rotation-symmetric structure. The current distribution in the transmitter is regulated to orient the transmitter magnetic field towards the receiver pad within a 2-D misalignment range. The magnetic field orientation is based on the discrepancy in the coupling coefficient between the different repeater coils and the receiver coil, which is obtained by detecting the current in the exciter coil when the repeater coils are connected alternately. Hence, no additional communication devices or detection coils are required. A nonlinear programming model for maximizing the overall coil-to-coil efficiency is formulated to determine the compensation parameters of the system, with the zero phase angle input and the constant current output conditions involved in the model. According to the experimental results, in the 60 mm 2-D misalignment case (50% of the receiver coil diameter), the proposed system achieves 88.2% coil-to-coil efficiency, which is 2.9 percentage points higher than a two-coil WPT system. Meanwhile, it at most reduces the magnetic flux leakage by 30.4% compared to the latter.