Staff publications (SoE)

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Browsing Staff publications (SoE) by Author "Aldhaher, Samer"

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    Electronic tuning of misaligned coils in wireless power transfer systems
    (IEEE Institute of Electrical and Electronics, 2014-11-01T00:00:00Z) Aldhaher, Samer; Luk, Patrick Chi-Kwong; Whidborne, James F.
    The misalignment and displacement of inductively coupled coils in a wireless power transfer system (WPT) can degrade the power efficiency and limit the amount of power that can be transferred. Coil misalignment leads the primary coil driver to operate in an untuned state which causes non-optimum switching operation and results in an increase in switching losses. This paper presents a novel method to electronically tune a Class E inverter used as a primary coil driver in an inductive WPT system to minimize the detrimental effects of misalignment between the inductively coupled coils which may occur during operation. The tuning method uses current controlled inductors (saturable reactors) and a variable switching frequency to achieve optimum switching conditions regardless of the misalignment. Mathematical analysis is performed on a Class E inverter based on an improved model of a resonant inductive link. Experimental results are presented to confirm the analysis approach and the suitability of the proposed tuning method.
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    Tuning Class E Inverters Applied In Inductive Links Using Saturable Reactors
    (IEEE Institute of Electrical and Electronics, 2014-06-01T00:00:00Z) Aldhaher, Samer; Luk, Patrick Chi-Kwong; Whidborne, James F.
    This paper investigates the performance of Class E inverters used in wireless power transfer applications based on resonant inductive coupling. The variations in the load and the distance between the coils cause Class E inverters to operate in non-optimal switching conditions, which result in inefficient operation and can lead to permanent damage to its switching transistor. Therefore, a novel approach to tune Class E inverters electronically is proposed. The tuning method relies on saturable reactors to ensure that the inverter operates at optimal switching conditions regardless of variations in the load and the distance between the coils. In addition, a more accurate model of inductive links is presented in order to provide a better understanding of the major power losses in resonant inductive links. Experimental results are presented to confirm the improved accuracy of the inductive link model and the validity of the tuning method.
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    Wireless Power Transfer Using Class E Inverter With Saturable DC-Feed Inductor
    (IEEE Institute of Electrical and Electronics, 2014-07-31T00:00:00Z) Aldhaher, Samer; Luk, Patrick Chi-Kwong; Bati, Akram F.
    Resonant converters used as coil drivers in inductive links generally operate efficiently at optimum switching conditions for constant load values and ranges. Changes in load and range can shift the operation of the coil driver to a non-optimum switching state which results in higher switching losses and reduced output power levels. This paper presents a method to adapt to variations in range for a Class E inverter used as a coil driver in a wireless power transfer (WPT) system based on inductive coupling. It is shown that by controlling the duty cycle of the inverter’s switch and the value of its DC-feed inductance, the Class E inverter can be tuned to operate at optimum switching conditions as the distance between the coils of the WPT system changes. Mathematical analysis is presented based on a linear piecewise state-space representation of the inverter and the inductive link. Extensive experimental results are presented to verify the performed analysis and validity of the proposed tuning procedure.