Wireless Power Transmission – WPT - PowerPoint Presentation

1. Wireless Power Transmission – WPTA status reportDon Beattie, G3BJ

2. TopicsWhat is happening? What is WPT?What are the plans for WPT?What are the technical characteristics of WPT?What problems could this create?What action is needed?

3. ITU – what is happening (1)?Question 210-3 (January 2013):1 Under what category of spectrum use should administrations consider WPT: ISM, or other?2 What radio frequency bands are most suitable for WPT?3 What steps are required to ensure that radiocommunication services, including the radio astronomy service, are protected from WPT operations?

4. ITU – what is happening (2)?WRC19 agenda Item 9.1.6:Studies concerning Wireless Power Transmission (WPT) for electric vehicles: to assess the impact of WPT for electric vehicles on radiocommunication services; to study suitable harmonized frequency ranges which would minimize the impact on radiocommunication services from WPT for electrical vehicles.

5. What is WPT?Is it a “Short Range Device” ?Is it ISM (Industrial, Scientific and Medical)Different spurious emission “rules” for each. SRD -> defined by CEPT and ITU emission limitsISM -> defined by CISPR limitsBoth are similar, and inadequateThis uncertainty is making the issue of spurious emissions a complex process and manufacturers are likely to argue for the route which demands the least strict limits

6. What’s happened?Intensive work in CISPR, CEPT and ITU. Some work in other RTOsCEPT Report 289Various draft recommendations in ITUArguments in CISPR about calculation of emission limitsAlthough there are differing views on how to treat WPT: SRD or ISM, in both cases no change felt necessary in Radio RegulationsBUT…….this only concerns the operating frequency of WPTThe real problem is the spurious emission level from WPT

7. Signal-to-noise ratios in the amateur serviceBased on 528,000 data points over a 2 x 24 hour periodbetween 1.8-30 MHzThe amateur service is thereforehighly susceptible to any increasein the background noise level.

8. What is WPT?Wireless charging of a range of devices at varying power levelsFrequencies being planned:19-21 kHz for high power55-65 kHz for medium power (but some concerns)79-90 kHz for medium power100-148.5 kHz for lower power (but still up to 2.4 kW!)Currently all subject to spurious limits at ERC Rec 74-01/SM.329/CISPR11 levels

9. What is WPT(EV)?

10. WPT(EV) in the home environment Charges the car through induction via a pad under the vehicle, rather than “plug-in”Power levels from 3.3 to 22 kWLikely to operate around 85 kHz. The harmonics could cause severe interference to local radio reception – both amateur and broadcast. Charge times of 3-12 hours64 installations per km2 (=never more than 88m from one)Frequency stability and phase noise uncertainCEPT intends to classify as a “Short Range Device” (SRD)SRDs & ISM are not permitted to cause interference to radio services! But what is “interference”?

11. What is WPT (Generic)?In-home devices for charging a range of devices:Mobile phones and accessories, cameras, AV equipmentPower tools, laptops, lighting, household devices, furniture, television, robots (both domestic and industrial), healthcare, e-bikes, drones, garden equipmentKitchen appliances (blender, rice-cooker, fryer, mixer), lighting, kitchen countertopsMainly long-duration chargingHigh density of deployment (6,500/km2) Generally 100-148.5 kHz

12. Projected MINIMUM spurious emissions - EV Frequency-Adjustment -> 30m (dB)Level at 62.5m cf 10m (dB)Level at 88m cf 10m (dB)Absolute level @ 88m with emissions at 10m @ ITU-R SM.329dBµA/mdB above background noise @ 88m (residential/rural)dB above background noise @ 30m(residential/rural)900 kHz-27.5-46.6-49.6-40.67.2/3.129.3/25.21.6 MHz-26.0-32.4-35.4-28.88.4/14.427.8/33.81.8 MHz-25.5-32.4-35.4-29.48.8/13.818.7/23.75 MHz-18.2-24.4-27.4-25.815.5/21.524.7/30.710 MHz-10-16.3-19.3-20.324/2933.3/38.3

13. Projected MINIMUM spurious emissions - genericGeneric WPTInstalled density projected means maximum distance from a WPT installation is 10m in urban areas. So minimum spurious emission is at ERC 74-01 level – about 40 dB above background noise if equipment “just” meets the 74-01 specification. In 78% of cases the emissions will be 9 dB above ERC 74-01 levelsHowever, data from Apple suggests emissions from tested devices may be as good as – 30 dB ref ERC 74-01 - closer to the IARU requested levels

14. SRD In the past, Short Range Devices in the home environment have been:Low power, and/orShort duration transmissionWPT is neitherSome have suggested that existing spurious emission limits for inductive SRDs are appropriate. CISPR limits assume intermittency and distance spacing, which do not apply to WPT. WPT is generally high duty cycle, located in residential areas and its harmonics are likely to be spread across a band of frequencies in comes cases the whole of the HF spectrum

15. The CEPT / ITU limits and the noise levelNote limits are some 40-60dB above noise level at 10m distance. CISPR 11 is similar (not shown). This is also the generic WPT MINIMUM impact levelRecent measurements in UK on noise levels and other reports submitted to ITU suggest that, with the exception of a few “hot spots”, the ITU-R P372 levels are still a reasonable assessment of the real worldWPT EV MINIMUM impact of spurious emissions (@88m)

16. Modelled harmonic field strength WPT-EV

17. Modelled harmonic field strength WPT-EV

18. WPT at these limits will severely impact radio receptionEC Decision 2006/771/EC states: Member States shall designate and make available, on a non- exclusive, non-interference and non-protected basis, the frequency bands for the categories of short-range devices. ‘Non-interference and non-protected basis’ means that no harmful interference may be caused to any radio communications serviceITU RR 15.13 states Administrations shall take all practicable and necessary steps to ensure that radiation from equipment used for industrial, scientific and medical applications is minimal and that, outside the bands designated for use by this equipment, radiation from such equipment is at a level that does not cause harmful interference to a radiocommunication service and, in particular, to a radionavigation or any other safety service operating in accordance with the provisions of these Regulations A very significant improvement is needed in emission limits to prevent extensive harmful interference to radio services

19. MitigationThe impact of WPT harmonics can be reduced if:All WPT installations adopt a single highly accurate fundamental frequency – meaning all harmonics are on “spot frequencies” rather than spread across the spectrumAll WPT systems have a very good phase and sideband noise performanceFor generic WPT this is simply not possible

20. What has IARU done?IARU historically slow to respond ! “Monitoring but not initiating or intervening”Now have deep involvement in CEPT SE24, WGSE, WGFM, SRD/MG, CISPR and ITU SG1 Not active in ETSI yet. Resource limitations.Active in ITU SG1/WP1B considering fundamental frequency choice and unwanted emissions CEPT Report 289 now published. Makes clear the adverse impact on broadcasting, amateur and land fixed/mobile servicesArguing in CISPR for new probability factors in the application of CISPR11 to WPTBriefing to NATO in Brussels in October 2017Working with BBC, EBU and the military where we have common agendaBriefs released to all Regions and via WRC ReflectorBut we need more people and more activity in MS with their administrations/NSOs. How do we get this?