Design of a self-tuning wireless power transfer system for low power application using capacitive approach

• Main Author: Hasan, Khairul Kamarudin
• Format: Thesis
• Language: English; English
• Published: 2021
• Subjects: T Technology (General); TK Electrical engineering. Electronics Nuclear engineering
• Online Access: http://eprints.utem.edu.my/id/eprint/26095/1/Design%20of%20a%20self-tuning%20wireless%20power%20transfer%20system%20for%20low%20power%20application%20using%20capacitive%20approach.pdf; http://eprints.utem.edu.my/id/eprint/26095/2/Design%20of%20a%20self-tuning%20wireless%20power%20transfer%20system%20for%20low%20power%20application%20using%20capacitive%20approach.pdf; http://eprints.utem.edu.my/id/eprint/26095/; https://plh.utem.edu.my/cgi-bin/koha/opac-detail.pl?biblionumber=121350

Since a decade ago, the Wireless Power Transfer Techonology has gain significant attention from researchers around the world. The popularity mainly due to the ability of tranferring power without physical connection especially in short distance power transfer applications. This short distance power transfer is normally from a few milimetre (mm) to a few metre (m) and this is commonly known as near field application. The main research interest is in the area of Capacitive Power Transfer (CPT) as a potential contactless power transfer option. The use of an electric field as an energy transfer medium provides CPT the advantages of confining the electric field between coupling plates, therein allowing power transfer through metal barriers. CPT also reduces eddy current power losses from metal surroundings including the potential to minimize circuit size and cost. Certain studies selected a maximum transfer distance of other applications at about 1 mm with similar impedance at both transfer unit and receiver unit in order to attain maximum efficiency. However tha main issue of CPT system is the variation in the plate transfer distance, its affects most of the applications in terms of their system efficiency and power of receiving at load. To overcome the mentioned problem, this thesis proposes a self-tuning frequency resonant technique for Class E-LCCL CPT system with impedance matching circuit topology to improve efficiency to address varying distances between capacitive coupling plates. The thesis begins by analysing the Class-E resonant inverter performance to generate a high frequency AC power source to drive the CPT system. Second, by utilizing a compensation network as an impedance converter to enable power transfer efficiently between two stages with a Class-E combined with LCCL compensation network topology for both transmitter and receiver is proposed as a method to provide impedance matching and hence, keeping the Zero Voltage Switching (ZVS) in good condition for wider distance range. Finally, the optimum efficiency of the Class-E LCCL CPT system was determined by employing the frequency tuning method during changes in the capacitive plates distance. Specifically, simulation and experimental works were done to analyse the developed Class-E LCCL CPT system with a 24 V DC supply voltage and 1 MHz operating frequency. With an air gap distance of 0.1 cm, the designed CPT system prototype successfully achieved a power output of 10 W and 95.45% efficiency. When the distance of the coupling plates was changed in the range of 1mm to 10mm, the original efficiency decreased from 95.45% to 72.06%. To overcome this efficiency-drop, the frequency tuning approach is proposed as a method to maintain the output efficiency despite the change in distance. In this study, an Arduino Uno pulse-width modulation (PWM) controller was used to tune the resonant frequency accordingly. By using this method, the original efficiency decreased only from 95.45% to 80.08% with varied frequency. These findings could be beneficial for household apparatus, medical implants, and charging consumer electronics.