Abstract
"Energy transmission usually needs to be achieved through a specific carrier. Currently, the most mainstream energy transmission method is still achieved through the movement of electrons in a continuous conductor. However, the limitations of this transmission method are very obvious, especially when the object is moving. Although there are various methods of wireless energy transmission, most of them are limited to a limited distance. For example, the working distance of the most common coil-based wireless energy transmission can usually only be maintained at the centimeter level. Therefore, finding more efficient ways of long-distance energy transmission has become an extremely important research topic.Electromagnetic waves can maintain high energy transmission efficiency in air and vacuum, and can greatly increase the distance of energy transmission, so they are regarded as one of the best ways to transmit energy over long distances. In this thesis, a highly intelligent long-distance wireless charging system is proposed, which is currently the most intelligent far-field wireless power transmission system with complex integrated functions such as continuous target locking, beamforming and human radiation protection.
The system uses lidar to achieve efficient spatial perception capabilities. With the support of intelligent systems, it can continuously identify multiple objects and track targets. The ultra-low axial ratio circularly polarized transmitting antenna array greatly reduces the sensitivity of target space and azimuth changes with a minimum axial ratio of 0.057 dB and a gain of 26.5 dB, and the high-performance ceramic base material also enhances the energy transmission efficiency. On the transmitter side, the 6-bit 16-way transmission channel is integrated in the chassis to maintain high-precision focusing. On the receiver side, the rectifier with an efficiency of up to 66.8% can operate stably under the condition of 2.4 W output DC power.
The filter is an important component in the RF WPT process, as the allocation of frequency spectrum is becoming increasingly dense. Reconfigurable filters are extensively utilized across various sectors, especially where the RF energy needs to be accurately measured. In this thesis, a dual-band reconfigurable (switchable) microstrip bandpass filter that operates in two sub-6 GHz frequency bands using a controllable grounding topology (CGT) is presented. This filter can achieve an exceptionally fast tuning speed of approximately 2 ns, requires a low bias voltage of around 3.0 V, and exhibits high linearity with a third-order intercept point (IP3) of up to +42.5 dBm. To minimize interference from the bias circuit, a multilayer design is employed. Additionally, a portable signal detector is designed to measure the RF signal strength, highlighting the promising application prospects of the developed switchable bandpass filter.
In the end, the system achieved watt-level energy transmission at a distance of nearly 1 m, and successfully drove a vehicle without a battery at a distance of more than 1.3 m. The UI system was demonstrated to show the high-level intelligence of the RF WPT system. In addition, high-performance reconfigurable filters were also designed for signal strength detection and signal source filtering.
This research is a milestone achievement in the current RF WPT field. It is also one of the very few complete and intelligent RF WPT systems. It also provides a new development direction for the large-scale application of RF WPT in the future.
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| Date of Award | 2025 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Supervisor | Wei XU (Supervisor) & Weijia Wen (Supervisor) |
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- Standard