scholarly journals Flat-topped beam forming experiment for microwave power transfer system to a vehicle roof

2015 ◽  
Vol 2 (1) ◽  
pp. 15-21 ◽  
Author(s):  
Takaki Ishikawa ◽  
Naoki Shinohara
Keyword(s):  
Conversion Efficiency ◽  
Microwave Power ◽  
Power Level ◽  
Input Power ◽  
Beam Pattern ◽  
Antenna Element ◽  
Transfer System ◽  
Power Transfer ◽  
Phased Array Antenna ◽  
Transmitting Antenna

We proposed and examined a microwave power transfer system for electric vehicles (EVs). In this system, electricity is transmitted from a transmitting antenna over an EV to a receiving antenna on the roof of the EV. We used a rectenna to convert the received microwave power to direct current power. The conversion efficiency of a rectenna array is affected by the input power level distribution, and we have to form a flat-topped beam pattern to increase the conversion efficiency. We conducted an experiment to form a flat-topped beam pattern by using a phased array antenna. In this experiment, the output power of each antenna element is uniform and cannot be controlled independently. Hence, we controlled only the output phases of each antenna element and formed a flat-topped beam pattern. The distance between the transmitting antenna and the receiving area is 6.45 m, and the receiving area corresponds to a space in which the azimuth and elevation are in the range of −5°–5°.

scholarly journals A Converter with Automatic Stage Transition Control for Inductive Power Transfer

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5268
Author(s):  
Lin Chen ◽  
Jianfeng Hong ◽  
Zaifa Lin ◽  
Daqing Luo ◽  
Mingjie Guan ◽  
...  
Keyword(s):  
Input Power ◽  
Effective Control ◽  
Transfer System ◽  
Injection Time ◽  
Power Transfer ◽  
Soft Switch ◽  
Inductive Power Transfer ◽  
Transition Control ◽  
Stage Transition ◽  
Inductive Power

An automatic stage transition converter for an inductive power transfer system is presented in this paper. An effective control strategy with two working stages of independent energy injection stage and free resonance stage is employed in the proposed converter. With the automatic stage transition strategy, when the frequency of the resonance network changes, the ending time of the free resonance stage is automatically determined. At the same time, the phase angle of the free resonance stage is automatically set as half a resonant cycle. As the stage transition is not triggered by the switches, the switch motion can be executed in advance of the transition moments. Time margins are offered for every switch in the converter, which make the switching moments of the switches flexible and the control simple. Another feature of this converter is that during the energy injection stage, the energy is injected into the inductor independently. Therefore, the input power can be easily regulated by adjusting the energy injection time. A prototype for the converter and the inductive power transfer system was implemented experimentally. From the experimental results, the automatic stage transition and power regulation capability of the proposed converter are verified. The switches all operated at the soft switch condition. When the energy injection time was adjusted from 10 μs to 25 μs, the output power changed from 143 W to 740 W.

scholarly journals A Wideband Rectenna Using High Gain Fractal Planar Monopole Antenna Array for RF Energy Scavenging

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Mohammad M. Fakharian
Keyword(s):  
Antenna Array ◽  
Conversion Efficiency ◽  
Power Level ◽  
Impedance Matching ◽  
High Gain ◽  
Input Power ◽  
Monopole Antenna ◽  
Energy Scavenging ◽  
Wireless Power ◽  
Circuit Performance

This paper introduces a wideband rectenna that can scavenge ambient wireless power to a range of frequency band from 0.91 GHz to 2.55 GHz efficiently. The proposed rectenna is based on a wideband 2 × 2 fractal monopole antenna array with omnidirectional radiation patterns and high gains of 5 to 8.3 dBi at the desired bands. An improved two-branch impedance matching technique is presented which is designed to enhance the rectifier circuit performance with a relatively low input power ranging from −25 dBm to 10 dBm. Also, a full-wave wideband rectifier that can suitably improve the RF-to-DC power conversion efficiency is designed for the rectenna. A peak efficiency of 76%, 71%, 61%, and 62% is obtained at 950, 1850, 2100, and 2450 MHz, respectively. Measurement results show that a conversion efficiency of 68% has been achieved over an optimal 4.7 kΩ resistor when the simultaneous four-band input power level is −10 dBm. Moreover, an output DC voltage of around 243 mV with voltage varying within 160–250 mV can be achieved by gathering the low ambient wireless power inside laboratory. This study proves that the proposed rectenna can be applied to a range of many low-power electronic applications.

scholarly journals Wireless Power Transfer to a Microaerial Vehicle with a Microwave Active Phased Array

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Shotaro Nako ◽  
Kenta Okuda ◽  
Kengo Miyashiro ◽  
Kimiya Komurasaki ◽  
Hiroyuki Koizumi
Keyword(s):  
Phased Array ◽  
Wireless Power Transfer ◽  
Axial Ratio ◽  
Input Power ◽  
Power Transfer ◽  
Wireless Power ◽  
Phased Array Antenna ◽  
Power Fluctuation ◽  
Microwave Beam ◽  
Yaw Angle

A wireless power transfer system using a microwave active phased array was developed. In the system, power is transferred to a circling microaerial vehicle (MAV) by a microwave beam of 5.8 GHz, which is formed and directed to the MAV using an active phased array antenna. The MAV is expected to support observation of areas that humans cannot reach. The power beam is formed by the phased array with eight antenna elements. Input power is about 5.6 W. The peak power density at 1,500 mm altitude was 2.63 mW/cm2. The power is sent to a circling MAV. Therefore, the transfer beam should be polarized circularly to achieve a constant power supply independent of its yaw angle. To minimize the polarization loss, a sequentially routed antenna (SRA) was applied to the transmitter antenna. Results show that the axial ratio of 0.440 dB was accomplished and that power fluctuation was kept below 1%.

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