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.

This paper presents a novel three-phase DC-link multilevel inverter topology with reduced number of input DC power supplies. The proposed inverter consists of series-connected half-bridge modules to generate the multilevel waveform and a simple H-bridge module, acting as a polarity generator. The inverter output voltage is transferred to the load through a three-phase transformer, which facilitates a galvanic isolation between the inverter and the load. The proposed topology features many advantages when compared with the conventional multilevel inverters proposed in the literatures. These features include scalability, simple control, reduced number of DC voltage sources and less devices count. A simple sinusoidal pulse-width modulation technique is employed to control the proposed inverter. The performance of the inverter is evaluated under different loading conditions and a comparison with some existing topologies is also presented. The feasibility and effectiveness of the proposed inverter are confirmed through simulation and experimental studies using a scaled down low-voltage laboratory prototype.

This paper presents a new compact three-phase cascaded multilevel inverter (CMLI) topology with reduced device count and high frequency magnetic link. The proposed topology overcomes the predominant limitation of separate DC power supplies, which CMLI always require. The high frequency magnetic link also provides a galvanic isolation between the input and output sides of the inverter, which is essential for various grid-connected applications. The proposed topology utilizes an asymmetric inverter configuration that consists of cascaded H-bridge cells and a conventional three-phase two-level inverter. A toroidal core is employed for the high frequency magnetic link to ensure compact size and high-power density. Compared with counterpart CMLI topologies available in the literatures, the proposed inverter has the advantage of utilizing the least number of power electronic components without compromising the overall performance, particularly when a high number of output voltage levels is required. The feasibility of the proposed inverter is confirmed through extensive simulation and experimentally validated studies.

This paper presents a new method to measure the voltage across the submodule (SM) capacitors in a modular multilevel converter (MMC). The proposed technique requires only one voltage sensor per arm. This reduces the number of sensors required compared with conventional sensor-based methods. Therefore, the cost and complexity of the system are reduced, which in turn improves the converter's overall reliability. The proposed method employs an exponentially weighted recursive least square algorithm to estimate the SM capacitor voltages through the measured total arm voltage and the switching patterns of each SM. There is thus no need for extra sensors to measure these control signals as they are directly provided from the controller. The robustness of the proposed method is confirmed via introducing deviations for the capacitance values, dynamic load changes, dc voltage change, and startup transient condition. Simulation and experimentally validated results based on a single-phase MMC show the effectiveness of the proposed method in both, steady-state and dynamic operations.