Post on 13-Feb-2021
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Electromagnetic design of Qi in system
Liu,Xun(Ken)
ConvenientPower
16-June-2016
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Base station-Mobile device (BM) system
Base station
Transmitter
Mobile device
Receiver
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Electromagnetic design of Rx in a BM system
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Ifixit.com
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Rx circuit model in a BM system
Ls’=Ls+ΔLs1+ΔLs2
Rs’
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Inductance
-5
0
5
10
15
20
1 2 3 4 5
Ind
uct
ance
(μH
)
Coil module example #
Ls ΔLs1 ΔLs2
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Secondary resonance
Other mobile device components (like battery, other metal parts inside the device…)
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Resistance
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
1 2 3 4 5
Res
ista
nce
(o
hm
)
Coil module example #
Rs ΔRs1 ΔRs2
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Why?
Ferrite shielding Metal
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FOD, Friendly metal
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Electromagnetic design of Rx in a BM system -Summary
• Ls’– Secondary resonance in BM system
– Secondary resonance in BM in power transfer
• WPC specification Part1&2 Annex C.1
• Rs’– FOD, received power,
– Procedure for Registration of Substantial Similar Products
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Electromagnetic design of Tx in a BM system
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High and controlled Electromagnetic Power Density enabled by localized charging
Example of a five devices charging plate generating simultaneously five high power density spots in a large coil array. One or several overlapping coils will be activated based on the position of the receivers ‘Rx’ on the pad.
Localized charging is important
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Coil size is important
• Coil(s) needs to have similar size with reference transmitters (e.g. Test Power Transmitter #1)
• Because….– Rx (or Mobile-device) was mostly designed for TPT#1
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Uniform Flux Distribution is importantSimulation Data comparing coil array solutions
each time only a single coil excited‘A’ type transmitter
every time one or more than one coil excited‘B’ type transmitter
Rx Receiver Tx Transmitter
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Coupling coefficient between Rx and ‘A’ type Tx
Coupling coefficient between Rx and ‘B’ type Tx
Rx Receiver Tx Transmitter
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Coil 2 excited Coil 3 excited Coil 3 excited Both Coil 2 & 3 excited
Flux distribution of ‘A’ type Tx Flux distribution of ‘B’ type Tx
Rx Receiver Tx Transmitter
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Increased Z
Interface
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Conclusions
• When electromagnetic design is to be done for transmitter or receiver, whole BM system needs to be taken into consideration.