Capacitive Power Transfer with Advanced Compensation and Power Flow Control

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dc.contributor.advisor Hu, AP en Huang, Liang en 2016-10-31T20:43:53Z en 2016 en
dc.identifier.uri en
dc.description.abstract In the past few decades, wireless/contactless power transfer technologies have become increasingly popular owing to their capability to deliver power to movable loads without direct electrical contacts between the primary transmitter and secondary pickups. Inductive Power Transfer (IPT) technology has been the most successful wireless power transfer solution, which has been commercialized in many domestic, industrial, and biomedical applications. However, because IPT is based on magnetic field coupling, it is unable to transfer power through metal barriers. In addition, the ferrite materials commonly used in IPT systems increase the system cost and size. Recently, Capacitive Power Transfer (CPT) has been proposed as an alternative wireless power transfer technology based on electric field coupling, which has the potential to transfer power through metal barriers, as well as other advantageous features such as low EMI and small volume. Some fundamental research on the CPT system has been conducted for understanding its working principle and improving its performance, but more advanced compensation and control methods are necessary to enhance its power transfer performance. In this thesis, a general circuit model is developed to characterize the capacitive coupling interface of CPT with cross coupling. The model consists of an input capacitor, an output capacitor, and an ideal transformer with a turns ratio, which can be used to significantly simplify the design process of CPT systems. Furthermore, based on the charge balance principle, a new term named capacitive coupling coefficient has been defined to quantify the mutual coupling between the primary and secondary coupling plates. The proposed model and the defined term are based on rigorous mathematical derivation and also validated by experimental results. Another significant contribution of this research is a development of a Z-impedance compensation network to cancel out the capacitive reactance of the capacitive coupling interface. The new compensation network can eliminate high voltage spikes suffered by conventional CPT systems with series inductor compensation when the secondary side plates are suddenly moved away. It also brings advantages such as short-circuit immunity and voltage boost capability. Based on thorough comparative study on three typical soft switching converters, a half bridge resonant converter is selected to drive a practical CPT system with the proposed Z impedance compensation network. Simulations and practical results have demonstrated the Z-impedance network can effectively compensate for the effective reactance of the capacitive coupling interface with short-circuit and open-circuit immunity. To achieve a controllable output power, a new power flow control method by switching the shunt capacitors of a CPT system is proposed. The system is designed to operate in a new sub-optimum mode of Class E converter, which is able to maintain soft-switching condition while controlling the output power according to the load requirements. Simulations and experimental results have indicated that the proposed control method can control the output power of CPT system with zero-voltage switching (ZVS) condition guaranteed. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof PhD Thesis - University of Auckland en
dc.relation.isreferencedby UoA99264895784002091 en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights.uri en
dc.rights.uri en
dc.title Capacitive Power Transfer with Advanced Compensation and Power Flow Control en
dc.type Thesis en Electrical and Computer Engineering en The University of Auckland en Doctoral en PhD en
dc.rights.holder Copyright: The author en
dc.rights.accessrights en
pubs.elements-id 544310 en
pubs.record-created-at-source-date 2016-11-01 en

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