Ziwei Xu

This article proposes a novel wireless power transfer (WPT) system, which achieves high misalignment tolerance in all directions by using antiparallel windings. The transmitter coil is composed of two parts of wires wound in opposite directions; thus, the magnetic flux with different directions would counteract partly. With the properly designed parameters, the mutual inductance between transmitter and receiver coils could remain constant when misalignment occurs. Therefore, the output power and the efficiency of the system can remain unchanged. Moreover, this article proposes a novel analytical calculation method for mutual inductance based on the truncated region eigenfunction expansion method, which greatly promotes and simplifies the design process of a magnetic coupler. This method solves the problem of mutual inductance calculation with a finite ferrite substrate. Factors that influence the mutual inductance of circular coils are systematically studied based on the method. Finally, an experimental prototype is built to verify the validity of the system. The mutual inductance can remain 97% of the well-aligned value within a 0.1-m misalignment, and the overall efficiency is consistently higher than 90.2%, while the fluctuation of the output power is within 3%.

The wireless power transfer (WPT) system has been widely researched due to its inherent advantages compared with the traditional plug‐in charging system over security, flexibility, convenience and so on. Compared with the two‐coil WPT system, the three‐coil WPT system has been proven to have higher efficiency over a relatively long transmission distance. In many applications, WPT systems are required to have the load‐independent constant current output (CCO) characteristic and zero phase angle (ZPA) operation. This study proposes a three‐coil WPT system that can achieve the CCO and ZPA operation through flexible parameter design. First, the detailed mathematical deduction for the CCO and ZPA operation is given. Then, a comprehensive analysis of the three‐coil WPT system is conducted in term of parameter design, the sensitivity of the CCO to changes in compensation parameters, implementation of zero voltage switching operation and efficiency analysis. Furthermore, a detailed efficiency comparison with the SS WPT system is performed to reflect the high efficiency of the proposed three‐coil system, and the additional performance of the proposed three‐coil system is compared with previous related works to verify its advantages further. Finally, the correctness of the theoretical analysis is verified by simulation and experiment.

In this paper, a novel long-distance wireless power transfer (WPT) system which achieves excellent constant current (CC) output based on Domino-Resonator is proposed. A thorough mathematical model of n-coil domino WPT system is established and the methodology of calculating and choosing the operating frequency in CC mode is put forward to achieve high efficiency and the best stability. Zero phase angle (ZPA) condition is proved to be realized in the meantime by theoretical derivation. The phenomenon that operating frequency slightly shifts away from the resonant frequency in CC mode due to the magnetic coupling between nonadjacent coils is studied. And the efficiency of the system is evaluated. Moreover, system efficiency can be further improved by optimizing number of the coils and layers when the transfer distance is fixed. An experimental setup with the output current of 0.6 A has been built to demonstrate the validity of the proposed system. The experimental results show that the maximum system efficiency of the experimental setup in CC mode can achieve 70% at the transfer distance of 0.7 m when the number of the coils is 8 and the radius of the coil is 100 mm.

The wireless power transfer (WPT) system has been extensively studied for its safety, convenience and aesthetics, and has gradually been introduced into our life applications. In order to maintain battery performance, constant current (CC) and constant voltage (CV) charging outputs are generally regarded as the dominant charging modes. However, battery equivalent resistance changes significantly during the charging, so it is difficult to simultaneously achieve load-independent CC and CV charging outputs and zero phase angle (ZPA) condition. This paper proposes a new LCCC/S topology and its corresponding parameter tuning method to obtain CC and CV charging modes at two different ZPA operating frequency points, respectively. In addition, it is worth mentioning that the receiver has only one compensation capacitor, which follows the principle that the receiver of the WPT system should remain compact and portable. Furthermore, a simple frequency modulation controller is designed to solve the problem of inaccuracies of the charging outputs due to parasitic losses of components and fluctuations of DC input voltage. Finally, a verification setup with 3A output current in CC mode and 48V output voltage in CV mode was built to validate the feasibility and rationality of the proposed LCCC/S compensated WPT system and the corresponding control method.