The wireless power transfer (WPT) method for electric vehicles (EVs) is becoming more popular, and to ensure the interoperability of WPT systems, the Society of Automotive Engineers (SAE) established the J2954 recommended practice (RP). It includes powering frequency, electrical parameters, specifications, testing procedures, and other contents for EV WPT. Specifically, it describes the ranges of self-inductances of the transmitting coil, the receiving coil, and coupling coefficient (k), as well as the impedance matching values of the WPT system. Following the electrical parameters listed in SAE J2954 RP is crucial to ensure the EV wireless charging system is interoperable. This paper introduces a method for adjusting the effective permeability of the ferrite blocks in the standard model, to tune the self-inductance of the coils as well as the coupling coefficient. To guarantee the given values of the self-inductance of the coil and coupling coefficient matched those in the standard, we slightly modified the air-gap between the ferrite tiles in a specific region. Based on this method, it was possible to successfully tune the self-inductance of the transmitting coil and receiving coil as well as the coupling coefficient. The proposed method was verified by simulation and experimental measurements.

Silicon carbide (SiC) devices can significantly increase power efficiency, temperature reliability, power capacity, and power density because of their outstanding characteristics. Nevertheless, in the bridge-leg configuration of a power converter, the high-speed switching capability of SiC mosfets is often restricted by the coupling noise between high-side mosfet and low-side mosfet. The coupling noise caused by high ${dv/dt}$ and ${di/dt}$ in switching transient will increase the switching loss and the risk of mosfet breakdown. In order to completely take advantage of the superior feature of SiC mosfets, a novel multilevel gate driver is proposed in this article to mitigate the coupling noise effectively. Compared to the conventional gate drivers, the proposed gate driver adds a capacitor, an auxiliary mosfet, a Zener diode, and two resistors to regulate the turn-off voltage bias felicitously. In this article, the operation principle of the proposed gate driver is first introduced, to the best of our knowledge. Moreover, to obtain the circuit parameters accurately, a series of formulas have also been derived by equivalent circuit models. A 230-V/4.6-A synchronous buck converter based on SiC mosfets is successfully experimented to verify this proposed gate driver.

With the increasing switching frequencies and power densities in modern power converters, the prediction and mitigation of common-mode (CM) noise are becoming increasingly essential. Even though powerful, simulation methods are hindered by the difficulties in modeling power semiconductors and the long simulation time. As an alternative, the measurement-based substitution model is demonstrated in the paper, which simplifies the non-linear converter with a linear circuit network with multiple independent sources. Transfer functions are then defined and characterized to evaluate the conversion ratio from different sources to the CM noise produced on the attached cables. Good agreements are observed between the predicted and measured CM noise under several test conditions. Additionally, the proposed method facilitates dominant noise source identification and the corresponding noise suppression. The proposed method offers advantages over the existing approach, including simplicity in the characterization of transfer functions and the least disturbance to the test setup.

Magnetic shielding sheets in wireless power transfer (WPT) systems exert a critical influence on both energy transfer efficiency and electromagnetic compatibility (EMC) performance. Commonly used high-performance layered nanocrystalline shielding sheets exhibit notable discrepancies between the effective permeability of their layered structures and the intrinsic permeability of the nanocrystalline flake ribbon materials. The design of their stacking critically determine the equivalent permeability of these shielding sheets. The precise characterization of permeability in layered nanocrystalline shielding sheets presents a challenge, which limits the accuracy of performance simulations in WPT systems. In addition, in recent widely used magnetic snap-on WPT applications, inadequate permanent magnet design can lead to the saturation of permeability in layered nanocrystalline shielding sheets, severely hindering power transfer efficiency. This study proposes an efficient method for rapid permeability characterization of layered nanocrystalline shielding sheets, solving the permanent magnet-influenced WPT challenge and preventing nanocrystalline saturation from bad permanent magnet design of magnetic snap-on WPT application.