Author: Li, Chenchen
Title: Soft switching techniques for driving circuits in wireless power transfer systems
Advisors: Yang, Yun (EEE)
Degree: M.Sc.
Year: 2023
Subject: Wireless power transmission
Electric vehicles -- Power supply
Switching power supplies
Hong Kong Polytechnic University -- Dissertations
Department: Department of Electrical Engineering
Pages: 62 pages : color illustrations
Language: English
Abstract: With the pursuit of green energy, electric vehicles have gradually entered people's lives. At present, electric vehicles are mainly charged by wired means. However, with the development of power electronics technology, wireless power transfer technology has gained people's attention. Compared with wired charging, the wireless power transmission system requires less maintenance and does not need to consider a series of losses caused by the grid's frequency, so it has more potential to improve efficiency. The main losses of the wireless charging system come from the losses between the coils and the losses of the energy conversion circuit. Coil losses can be reduced by replacing with higher-quality coils. The energy conversion circuit's loss is essentially the power device's switching loss, which can be reduced by soft switching technology. In this paper, the soft switching technology that can reduce the switching loss of WPT is taken as the research object, and the method of zero voltage switching (ZVS) is mainly studied. The main work and achievements of this paper are as follows:
First, a better method of adding auxiliary circuits is suggested based on the conduction concept of the conventional phase-shifted full-bridge application. The inductors or capacitors used in the auxiliary circuits are designed. The improved soft-switching of the power circuit is then demonstrated through simulation and experiment and it confirms that the added auxiliary circuit can improve the soft-switching problem without impacting the performance of other components of the system, such as the control circuit.
Finally, experiments are used to validate the load range and coil range corresponding to various auxiliary circuits. To preserve the circuit's maximum working efficiency in real-world applications, the auxiliary circuits of various gears can be automatically changed by keeping track of the position of the charging apparatus and the battery's condition.
Rights: All rights reserved
Access: restricted access

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