why not a wire?...current ti wireless power evm system ac-dc 60%-80% efficiency1 110vac/ 240vac 1....
TRANSCRIPT
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Kalyan Siddabattula System Architect bqTESLA Wireless Power Solutions TEXAS INSTRUMENTS
1
Why Not A Wire? The case for wireless power
http://dailyreporter.com/files/2009/07/powertheft-070709.jpg
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Wireless Power – Replaces A Wire • Wireless Power is a convenient method of transferring energy from one
physical device to a second physical device without contacts
• This allows devices to be powered or batteries to be charged
• It is mostly a convenience issue for consumers and offers
• Different methods or wireless power transfer are available based upon power level requirement and use case – Inductive resonant charging – Capacitive – Solar/Light – Vibratory – Audio
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Wireless Energy Transfer – Overview
Wireless Energy Transfer
Electromagnetic Induction
Electromagnetic Radiation
Electrodynamic Induction
Electrostatic Induction
Microwave/ RF Power
Light/ Laser Power
Inductive coupling Magnetic Resonant Induction
Near Field Far Field
Magnetic field Electric field
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Why Do Wireless Charging
• Convenience
• Convenience
• Convenience
• Connector fatigue and failure can be avoided
• Hermetically sealed devices are possible
• Ability to “graze” energy rather than “gorge” means users will have well charged devices when they pick up a device and go
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But It’s Not As Efficient As A Wire?!
• Isn’t a wire inherently more efficient than wireless? • Isn’t a wire 100% efficient? • What’s the maximum efficiency of wireless power transfer
anyway?
http://gomadic.us/imgs-prod/charger/sony-bloggie-touch-rapid-wall-ac-charger.jpg
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• Power transmitted through shared magnetic field – Transmit coil creates magnetic field – Receive coil in proximity converts field into voltage – Shielding material on each side directs field
• Power transferred only when needed – Transmitter waits until its field has been perturbed – Transmitter sends seek energy and waits for a digital response – If response is valid, power transfer begins
• Power transferred only at level needed – Receiver constantly monitors power received and delivered – Transmitter adjusts power sent based on receiver feedback – If feedback is lost, power transfer stops
I z < D
D
AC to DC Voltage Conditioning
Communication and Control
Rectification Drivers Li Ion Battery
Controller V/I Sense
Power
Transmitter Receiver
Communication
Wireless Power System Overview
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Current Wired charger
Typically Flyback
Losses
Transformer Electronics
Diode Rectification Regulation
Losses Rectifier
Regulation
110VAC/ 240VAC
DC voltage
From wall
Primary 80%-90% Efficiency
Secondary 80% - 90% Efficiency
Filter/Rectifier 95% Efficiency
Total System efficiency is ~ 50% to 64% TO BATTERY
When efficiency of wire (~95%) is included, System efficiency can be ~72% TO CHARGER or even less than 47% TO BATTERY
Diode Bridge
HF AC
Charger
5V 1.0A
Battery
85% Eff
4.35V 1.0A
Total System efficiency is ~ 60% to 76% TO CHARGER
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Current TI Wireless Power EVM System
AC-DC
60%-80% Efficiency1
110VAC/ 240VAC
1. Assuming 80% Adapter efficiency 2. All numbers are typical of a nominal interface gap of 3.7mm, optimal position 3. Peak efficiency shown is shown at 3.5W output power
Receiver 89% Efficiency
19VDC 5V
1.0A
Peak Electronics Efficiency 93%
HF AC
Transmitter 95% Efficiency
Coil to Coil 89% Efficiency
LV Half Bridge to energize Coil
Synchronous FB Regulator
Charger
DC System efficiency 75% TO CHARGER
Total System efficiency is 60%1 TO CHARGER
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bqTesla System Efficiency Breakdown
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Effic
ienc
y (%
)
Output Power (W)
Tx Eff. Magnetics Eff. Rx Eff. System Efficiency
System Eff
TX Eff Magnetics Eff
RX Eff
Measured from DC input of Transmitter to DC output of Receiver
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- Wireless power in series with existing system - Adapter sense turns off wireless power when adapter is present - Termination disables wireless power once charge is complete
RX Architecture – Main Board Power Supply
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RX Architecture – Main Board Charger
• Wired and wireless charger in parallel • Adapter sense turns off wireless charger when adapter is present • Highest efficiency solution when observing power transferred to the battery
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Direct Charging vs. Discrete Charging
Transmitter Receiver
Charger
System/ Battery
Discrete Charging Solution
Transmitter Receiver Charger
System/ Battery
Direct Charging Solution
Direct charging allows the RX to become the battery charger allowing for elimination of a power stage. This allows highest efficiency path and maximal use of thermal budget
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Efficiency Data Comparison-Direct vs. Discrete Charging Topologies
Over 10% improvement by going to direct charge
Direct charge solution allow you to turn off the “wired” charger and thus allow you to allocate the thermal budget of the “wired” charger to the “wireless” charger.
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RX Architecture – Output Voltage • Output Voltage can have a great impact on the efficiency • Coil and synchronous rectifier I2R losses are current based
50.00%
55.00%
60.00%
65.00%
70.00%
75.00%
80.00%
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Efficiency And Output Voltage
7V Vo Efficiency
5V Vo Efficiency
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WP Transformer
Voltage Regulation Architecture
TX
RX Sync Rect
DC Adapter
Buck Reg
Flyback One FET
H-Bridge Four FETS
H-Bridge Four FETS
Two FETS Inductor
Transformer
Buck Charger
Two FETS Inductor
TX
RX Sync Rect
DC Adapter
Dynamic LDO Reg
Flyback One FET
H-Bridge Four FETS
H-Bridge Four FETS
One FET NO Inductor
Transformer
Buck Charger
Two FETS Inductor
WP Transformer
Acts like a Buck
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Architecture Comparison
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Buck Architecture
TI -- Dynamic LDO
Architecture Comparison
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Next Gen TI Wireless Power EVM System
Charger
AC-DC 60%-80% Efficiency1
110VAC/ 240VAC
1. Assuming 80% Adapter efficiency 2. All numbers are typical of a nominal interface gap of 3.7mm, optimal position 3. Peak efficiency shown is shown at 3.5W output power
Receiver 95% Efficiency
19VDC
DC System efficiency 80% TO CHARGER
Peak Electronics Efficiency 96%
Total System efficiency is 65%1 TO CHARGER
HF AC
Transmitter 95% Efficiency
Coil to Coil 89% Efficiency
LV Half Bridge to energize Coil
Synchronous FB Regulator
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What Architecture Works Best?
Battery
110VAC/ 240VAC
1. All numbers are typical of a nominal interface gap of 3.7mm, optimal position 2. Peak efficiency shown is shown at 3.5W output power
Receiver 93% Efficiency
DC 4.35V 1.0A
Peak System efficiency 75% TO BATTERY
Total System efficiency is > 70% TO BATTERY
HF AC
Transmitter 88% Efficiency
Coil to Coil 89% Efficiency
Diode Bridge
Rectifier 95% Efficiency
HV Half Bridge to energize Coil
Synchronous FB Charger
Direct AC TX1 Direct Charge RX
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Potential Wireless Charging Implementations Compared
Wall Adapter Transmitter Receiver Expect Eff . AC to Battery
Comments
Current Wired Charger
N/A N/A ~ 50 - 65% As low as 47% when cable eff is included
19V DC Out Single Coil No Magnet
7V into Charger 52 % Best available Wireless Solution
Today
5V DC Out Single Coil No Magnet
7V into Charger 45 % 5V Adapter Design important
19V DC Out Single Coil No Magnet
Next Gen Direct charge 62% Direct charge offers higher
efficiency
None Direct AC TX Next Gen Direct charge 65 - 70% As good as wired?
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