Electric vehicles (EVs) are becoming increasingly popular as a mean of mitigating issues associated with fossil fuel consumption in transportation systems. A wireless inductive power transfer (IPT) interface between EV and the utility grid has several key advantages, such as safety, convenience, and isolation. However, physical misalignments between the pads of IPT charging systems used in EVs are unavoidable and cause variations in key system parameters, significantly increasing losses and affecting power throughput. This paper presents a novel series-hybrid topology in which the series inductors of the primary and pick-up LCL networks are integrated into polarized magnetic couplers to improve the system performance under pad misalignment. A mathematical model is developed to investigate the behavior of the proposed system under misalignment. To demonstrate the viability of the proposed method, the results of a 3.3 kW prototype series-hybrid IPT system are presented, benched marked against a conventional IPT system. Experimental results clearly indicate that the proposed system maintains the output power within μ5% of its rated power despite the pad misalignment. The proposed system is efficient, reliable and cost-effective in comparison to conventional LCL and CL compensated IPT systems.systems.

Wireless power transfer (WPT) is a promising technology for supplying power to various applications with no physical contacts. Recently, bidirectional wireless power transfer (BD-WPT) systems are gaining popularity for grid-to-vehicle and vehicle-to-grid applications which essentially require power transfer in both directions. However, BD-WPT systems are complex in nature, and require sophisticated control strategies to provide synchronization as well as to regulate the power flow between two sides. This paper proposes a new controller that uses measured active power (P) and reactive power (Q) at the resonant network of BD-WPT systems to regulate the power flow in both directions while providing synchronization between two sides without a dedicated communication interface for controlling power transfer. The controller, located on the pickup side, is applicable to BD-WPT systems with either single or multiple loads and ensures that the volt-ampere rating of the pickup converter is at lowest for battery charging, by keeping the reactive power at the resonant tank intake by the load side minimum. Experimental results obtained from a 1-kW prototype system show good agreement with simulated results, validating that the proposed controller can be used to regulate the power flow in BD-WPT systems.

Misalignment between charging coils is an unavoidable problem in all electric vehicle (EV) charging systems that are based on wireless power transfer (WPT) technology. This is because variations in both self- and mutual inductances of charging coils due to coil misalignments, significantly affect the charging rate and efficiency of the EV charger. As a solution, this paper proposes a new control technique that maintains the rated charging power level at optimum efficiency in spite of large coil misalignments. To compensate for the variations in inductances, the technique uses the information extracted from input impedance to operate the system essentially at unique converter voltages with zero-phase-angle (ZPA), ensuring that charging will take place at rated power with optimal efficiency despite any pad misalignments. The paper presents a comprehensive mathematical model, describing the theoretical basis of the proposed control philosophy. To demonstrate the validity of the proposed control concept, a 1 kW bi-directional WPT EV charging system is built and results are presented under misaligned coil conditions. Results convincingly indicate that the proposed controller is efficient and capable of maintaining the rated charging rate despite large coil misalignments and without any dedicated wireless communication.

Efficiency of wireless power transfer systems, based on inductive power transfer (IPT) technology, suffers significantly due to coil misalignment and load variations. Although numerous control strategies have been proposed in the past to improve the efficiency under these conditions, a technique that utilizes all freedoms of control simultaneously to maximize efficiency is yet to be reported. This paper therefore proposes a multi-variable control strategy that uses the optimal combination of all control variables to maximize the efficiency of IPT systems when regulating power and even under large coil misalignments and load variations. The paper presents a comprehensive mathematical model, describing the underlying theory of the proposed optimal control philosophy, and investigates the performance and limitations of the proposed technique under wide range of operating conditions. To demonstrate the improvement in performance, theoretical results are presented in comparison to those obtained from a 1 kW prototype bi-directional IPT system, and also benchmarking against conventional control techniques. Results convincingly indicate that the proposed optimal control strategy regulates power at maximum efficiency despite large coil misalignments and load variations.

Expandable and flexible wireless power transfer (WPT) systems have been in demand in numerous industry applications, especially for dynamic chargers in electric vehicles. Those systems, however, brings about certain technical issues such as modulation technique and topology of the transmitter-side, and transferred power profile of the transmitters. In this paper, a new converter topology to drive closely spaced segmented Dynamic Wireless Power Transfer (DWPT) systems is proposed. The proposed converter can be expanded to cater for different number of transmitters, and it can provide a uniform transferred power profile throughout the path of transmitter coils, known as track. Furthermore, this study focuses on analyzing the operation of the converter and the effect of closely spaced transmitters over its operation. To show the effectiveness of the proposed topology and its modulation technique, the converter is simulated and experimentally tested using a laboratory prototype. The results are compared and analyzed, and their close agreement shows the validity of the proposed technique.

This letter proposes a novel primary-side parameter estimation method for bi-directional inductive power transfer (BD-IPT) systems. This method can estimate mutual inductance at startup and monitor secondary-side phasor information continuously during operation. The proposed method can be used to simplify existing optimal control methods in BD-IPT systems by providing necessary feedback information without a wireless communication link. Besides, it helps to implement new control methods to further improve system performance. A current decoupling concept is utilized to estimate both the mutual inductance and secondary phasor information. A circuit model based on the superposition principle is presented to describe the current decoupling concept. The validity and accuracy of the proposed estimation method are demonstrated using the measured results of a 1kW prototype BD-IPT system.