Wireless Energy Harvesting from Hz to GHz

Transcription

1 Wireless Energy Harvesting from Hz to GHz Prof Yi HUANG ( 黄漪 ) Y. Shen, C. Song, J. Zhou and P. Carte Department of Electrical Engineering and Electronics

2 Prof Yi Huang Yi Huang received BSc in Physics (Wuhan University, China) in 1984, MSc (Eng) in Microwave Engineering (NRIET, Nanjing, China) in 1987, and DPhil in Communications from the Universityof Oxford, UK in He has been conducting research in the areas of wireless communications, applied electromagnetics, radar and antennas since His experience includes 3 years spent with NRIET (China) as a Radar Engineer and various periods with the Universities of Birmingham, Oxford, and Essex at the UK as a member of research staff. He worked as a Research Fellow at British Telecom Labs in 1994, and then joined the Department of Electrical Engineering & Electronics, the University of Liverpool, UK as a Faculty in 1995, where he is now a full Professor in Wireless Engineering, the Head of High Frequency Engineering Group and Deputy Head of Department. Prof Huang has published over 300 refereed papers in leading international journals and conference proceedings, and authored Antennas: from Theory to Practice (John Wiley, 2008) and Reverberation Chambers: Theory and Applications to EMC and Antenna Measurements (John Wiley, 2016). He has received many research grants from research councils, government agencies, charity, EU and industry, acted as a consultant to various companies, and served on a number of national and international technical committees and been an Editor, Associate Editor or Guest Editor of four of international journals. He has been a keynote/invited speaker and organiser of many conferences and workshops (e.g. WiCom 2006, 2010, IEEE iwat2010, and LAPC2012). He is at present the Editor-in-Chief of Wireless Engineering and Technology, Associate Editor of IEEE Antennas and Wireless Propagation Letters, UK and Ireland Rep to European Association of Antenna and Propagation (EurAAP), a Senior Member of IEEE, a Fellow of IET, and Senior Fellow of HEA. Yi Huang, 2

3 Happy 80th Birthday!

4 Outline Introduction What is wireless energy? Classification of wireless energy Wireless Energy Harvesting at Lower Freq. The approaches Results and discussions Wireless Energy Harvesting at Higher Freq. The approaches Results and discussions Summary Yi Huang, 4

5 Introduction What is wireless energy? We mean electromagnetic energy Yi Huang, 5

6 The wireless energy we are interested in this talk: Low frequency (Hz to khz) energy from such as a power line. High frequency (MHz to GHz) energy from such as WiFi and mobile signals The energy can be harvested using a rectenna Yi Huang, 6

7 What is a rectenna? It is a combination of rectifier and antenna, and an impedance matching network and DC pass filter may be required depending on the specific design. The main advantage is high efficiency over 80% which has been achieved at microwave frequencies. Yi Huang, 7

8 Outline Introduction What is wireless energy? Classification of wireless energy Wireless Energy Harvesting at Lower Freq. Our designs/approaches Results and discussions Wireless Energy Harvesting at Higher Freq. The approaches Results and discussions Summary Yi Huang, 8

9 Wireless Energy Harvesting at Lower Freq. Weather station Lightning detector Temperature Partial discharge Line sag Main Problem: How to power these wireless sensors in remote areas? Yi Huang, 9

10 Cable-clamped energy harvesters Limitations of conventional designs: De-energized to allow installation and maintenance Impossible to install a sensor with a large volume such as a weather station Further increase line sags Yi Huang, 10

11 We want a wireless one! Benefits: Easy to install and maintain Able to power the sensors with large volume Challenge: How to design and optimize this energy harvesting system to collect sufficient energy? Yi Huang, 11

12 Antenna Operation Principle Faraday s Law: When a coil is subjected into a time-varying magnetic field, voltage can be generated. VV cccccccc = ωωnnbb eeee μμ eeeeee AA 12

13 How to make it? Design 1 (bow-tie) N N N N N N μμ eeeeee = μμ rr 1 + DD MM (μμ r 1) S S S S S S Advantages: μμ eeeeee = 130 μμ eeeeee = North poles and south poles are separated further and the demagnetizing field is reduced 2. The large end surface allows more magnetic flux passingthroughthe core 3. Require shorter wire winding on the core and reducethe copperloss Yi Huang, 13

14 Comparison of different designs Benchmark 5 times The power density of the bow-tie coil can be 5 times larger than the solenoids Yi Huang, 14

15 How to make it: Design 2 (helical) The winding (enameled wire) The circular plate (ferromagnetic) The circular plate (ferromagnetic) The helical core (ferromagnetic material) 7 turns Effective length = 105 cm Yi Huang, 15

16 Coil Design 2: Helical Core More turns on the core, Better the performance. 12 turns 9 turns Bow-tie core 7 turns 5 turns 16

17 Helical Core Optimization When the inner radius D in equals to the supporting length L s, the winding area inside the helical core is fully utilized, which gives a max power density The change of helical width 17

18 Measured Results of Helical Coil When 2000 turns of wire can be wound, the predicted power density is around 9.8 µw/cm 3 The Coil Type Solenoid [7] Bow-tie Coil [9] Helical Coil Physical Length 50 cm 15 cm 15 cm Applied Flux Density The Number of Turns Power Density 0.85 µw/cm µt rms 18.5 µt rms 18.5 µt rms 40,000 40, times µw/cm µw/cm 3 5 times

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20 Results Comparisons Coil Design Testing Environment Physical Dimensions Power at Matched Load About 18 µt 50 cm long 3.923X10-3 m µw About 18 µt 15 cm long 1.885X10-3 m mw 20

21 21 More information 1. S. Yuan, Y. Huang, Q. Xu, J. Zhou, C. Song and G. Yuan, A highly efficient helical core for magnetic field energy harvesting, IEEE Transactions on Power Electronics, Vol. 32, July, S. Yuan, Y. Huang, Q. Xu, J. Zhou, C. Song and P. Thompson, Magnetic Field Energy Harvesting Under Overhead Power lines, IEEE Transactions on Power Electronics, Vol. 30, Issue 11, May, 2015.

22 Outline Introduction What is wireless energy? Classification of wireless energy Wireless Energy Harvesting at Lower Freq. The approaches Results and discussions Wireless Energy Harvesting at Higher Freq. The approaches Results and discussions Summary Yi Huang, 22

23 23 03/02/ :41 The idea Receive Convert Utilize Broadband Rectenna Broadba nd Antenna Matching Network RF-to-DC Rectifier Yi Huang, 23

24 Challenges Difficulties in broadband or multiband designs Low conversion ambient power level Strong nonlinear effects (e.g., load variation) Complex structure for the design etc. Yi Huang, 24

25 Our solutions No 1. High efficiency low power broadband rectenna C. Song, Y. Huang et al., A high-efficiency broadband rectenna for ambient wireless energy harvesting, IEEE Trans. Antennas Propag, May Yi Huang, 25

26 26 03/02/ :41 Results 2G, 4G mobile 3G mobile WiFi 0.3 V (6 uw) DC output power for -35 dbm ambient power level Significantly improved ambient power levels Yi Huang, 26

27 27 CHALLENGES Difficulties in broadband or multiband designs Low conversion ambient power level Strong nonlinear effects (e.g., load variation) Complex structure of the design etc.

28 28 No 2. Six-band CP rectenna with reduced load effects THE DESIGN A special section for reducing the impedance mismatch vs. load impedance

29 29 03/02/ :41 Results Covers the entire DTV, mobile, WiFi, and ISM bands Consistent efficiency, reduced nonlinear effect Yi Huang, 29

30 30 03/02/ :41 Antenna design Ultra wideband CP antenna for wireless energy harvesting High frequency mode (1 3 GHz) Low frequency mode ( MHz) Yi Huang, 30

31 31 03/02/ :41 Results Indoor (8 uw harvested power) Outdoor (24 uw harvested power) C. Song, Y. Huang et al., A novel six-band dual CP rectenna using improved impedance matching technique for ambient RF energy harvesting, IEEE Trans. Antennas Propag, July Yi Huang, 31

32 32 No 3. Improved wideband rectennas using hybrid resistance compression THE DESIGN

33 33 03/02/ :41 Results Consistent efficiency, reduced nonlinear effect Yi Huang, 33

34 34 CHALLENGES Difficulties in broadband or multiband designs Low conversion ambient power level Strong nonlinear effects (e.g., load variation) Complex structure of the design 03/02/ :41

35 35 No 4. Matching network elimination for broadband rectennas THE DESIGN

36 36 Off-centre-fed dipole Long arm (mm) Short arm (mm) Real part at f 0 (Ω)

37 37 Broadband high impedance antenna

38 38 03/02/ :41 Results Well matched with different types of diodes Yi Huang, 38

39 39 03/02/ :41 Results Reduced nonlinear effect vs. load variations Yi Huang, 39

40 40 03/02/ :41 APPLICATION Energy harvesting wireless sensors Broadba nd Rectenn Harvesting a Power Managem ent Circuit Tempera ture & Humidity Sensor Displ ay Self-powered Data Receiv er PC Yi Huang, 40

41 41 03/02/ :41 APPLICATION Back view Front view Yi Huang, 41

42 03/02/ :41 Yi Huang, 42

43 43 03/02/ :41 Impact Self-sustainable Wireless Sensors Yi Huang, 43

44 03/02/ :41 Be aware Yi Huang, 44

45 Summary We have used rectenna technology to harvest wireless energy at lower and higher frequencies. At lower frequencies, two special antenna designs have been produced. At higher frequencies, four special rectenna designs have been presented. They all have been validated by experiments and potential applications have been identified. Yi Huang, 45