Inductive power transfer (IPT) for electric vehicles (EVs) is an emerging technology that can transfer power wirelessly over certain distances, thus offering some remarkable characteristics in terms of flexibility, position, and movability. The output power of an IPT system depends on the coupling factor of the magnetic couplers, which can deviate from the nominal operating conditions due to the occurrence of misalignment. Nevertheless, misalignment of the magnetic couplers in inductive charging is inevitable, and it usually results in the variation of the mutual inductance and output power of the system with a corresponding decrease in the system’s overall efficiency. So far, the literature has reported various techniques for achieving designs with higher misalignment tolerance. The reported techniques can be mainly classified into three categories, as viewed from the following aspects: magnetic couplers layouts, compensation networks, and control strategy. Each of these techniques has its pros and cons in terms of implementation cost, system layout, efficiency, power density, and reliability depending on the application. With the increased investigation of more applications of IPT, new modified techniques for improving the misalignment tolerance in the IPT system are continuously being proposed based on permutations and combinations of the existing ones; thus causing some confusion and difficulties for researchers and system vendors to follow. This article, therefore, aims to provide a comprehensive review of the existing methods for IPT systems that address the misalignment issue in EVs’ wireless charging. The background of the inductive charging systems for EVs is presented and an investigation of the numerous factors affecting the output power and other performances is conducted. In addition, the advantages and disadvantages of each technique on the IPT system’s performance are analyzed in detail.

Wireless Dynamic Charging (WDC) of Electric Vehicles (EV) is a new initiative aimed to increase EV uptake. However, pulsating output power along the driving direction is a major problem with this technology. Moreover, in order to deliver enough driving power for EVs, WDC systems must operate at high power. This paper proposes a WDC system that has the capability of providing a low pulsating and high output power to EVs. The proposed WDC utilizes multiple primary windings that guarantees a homogeneous mutual magnetic flux for the receiver along the driving direction. This results in a constant induced voltage across the receiver and hence constant output power to charge the EV battery. High output power is realized by using multiple transmitter windings which have been arranged in a novel winding method. The structure layout of the proposed WDC, including ferrite cores, windings and resonant tanks is presented. Furthermore, a theoretical analysis is conducted to determine conditions of each winding’s current phase and amplitude for achieving constant output power. The crossing mutual inductances between the different transmitter’s phases are compensated by adding small capacitors in series with each transmitter winding. An optimization analysis using Maxwell 3D simulation for both, transmitter and receiver is carried out to achieve the highest coupling factor by using minimum ferrite material. The effectiveness of the proposed system is analytically demonstrated and experimentally verified using a 3-kW laboratory prototype. Finally, the performance of the proposed method is compared with similar systems presented in the literature. The comparison shows that the proposed system has the advantages of using simple control, it also eliminates communications between the primary and secondary side and delivers a normalized power of 2.25 which is 125% higher compared to conventional single-phase systems.

Power modules are the most common components to fail in power converters that are employed in mass transportation systems, thus leading to high unscheduled maintenance cost. While operating, high junction temperature swings occur that result in high thermomechanical stress within the structure of the power module, reducing the lifetime of the module. Liquid metals as a cooling medium received so far little attention in the area of power semiconductor cooling, despite being able to remove high heat fluxes. This paper shows for the first time how liquid metal is used to reduce actively the junction temperature swing. A magnetohydrodynamic (MHD) pump has been designed for this purpose allowing active control of the flow rate of the liquid metal that impinges against the baseplate of the module. The pump has been 3-D printed and is attached directly to the power module. A closed-loop temperature control system is implemented, able to estimate the insulated-gate bipolar transistor's junction temperature, and thus, controls the MHD power. This paper presents simulation and experimental results showing reductions in the temperature swing over the full load cycle with 12 °C as the highest observed reduction rate. This paper also shows detailed designs of the MHD pump and the controller hardware.

Temperature Sensitive Electrical Parameters (TSEPs) are promising for measurement of the IGBT chip temperature, Tchip. Many TSEPs have been proposed in the literature and most require current sensors, and convoluted hardware and data processing, which are associated with increased complexity and cost. In this letter, a new TSEP is proposed called pre-threshold TSEP, V$_{GE(pre-th)}$. V$_{GE(pre-th)}$ requires only a voltage sensor and a counter. Besides less hardware requirement, V$_{GE(pre-th)}$ does not suffer from self-heating – a problem that most TSEPs encounter. This letter presents the operation of V$_{GE(pre-th)}$ with the help of simulation. Experimental tests on a 3.3kV, 800A IGBT were conducted to characterize V$_{GE(pre-th)}$. It is shown that the new TSEP proposed has a sensitivity of -2.2mV/°C.