throbber
Power for a Wireless World
`
`Measuring Wireless
`Charging Efficiency
`In the Real World
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`Or…
`Why a Wireless Charging Spec
`needs to Support Close &
`Loosely-Coupled Approaches
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`
`
`Power for a Wireless WorldPower for a Wireless World
`
`Industry-Wide Problem:
`
`There is no Standardized test
`methodology for specifying power
`efficiency of a wireless charging system
`
`Battery Charger
`
`Buck Regulator
`
`Synchronous DC-DC
`
`WPT Transmitter
`
`WPT Receiver
`
`Bridge Driver
`
`DC
`Input
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`Efficiency
`Matters
`
`• Who cares about efficiency?
`• IKEA
`• McDonald’s
`• EPA/China/EU/ Gov’t agencies
`• Auto makers
`• Consumers
`• Who doesn’t care?
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`No Measurement
`Standard
`
`1. DC out A: Not a valid representation of real-world application
`2. DC out B: A good proxy, if the right load range is selected
`3. DC out C: The real-world view, also allows complete energy
`analysis
`
`DC Out
`A
`
`DC Out
`B
`
`DC Out
`C
`
`Battery Charger
`
`Buck Regulator
`
`Synchronous DC-DC
`
`WPT Transmitter
`
`WPT Receiver
`
`½ Bridge Driver
`
`DC
`Input
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`2 Architectures
`
`Resonant
`
`Inductive
`
`Rezence perimeter coil
`
`Qi planar coil
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`Architecture
`Comparison
`
`Architecture
`
`Representative
`Standards
`
`Operating
`Frequency
`
`Antenna
`Structure
`
`Benefits1
`
`Resonant
`AKA: Loosely
`Coupled
`
`• Rezence
`
`• 6.78 MHz
`
`Perimeter
`
`• Extended Z-distance
`• Multi-device
`
`Inductive
`AKA: Closely
`Coupled
`
`• Qi
`• PMA
`
`• 110 ~ 205 kHz
`• 200 ~ 300 kHz
`
`Planar
`
`• Highly efficient
`Low cost
`•
`
`Question: Why not use resonant architecture for all applications?
`Answer: Efficiency and cost tradeoffs make it inappropriate to do so.
`
`1. There are no Rezence products in the market, so benefits are as per the
`promotional materials from the A4WP
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`Use-Case
`Examples
`
`Inductive:
`Charging Stand
`
`Resonant: Under-surface mount
`
`Inductive: Automotive
`
`Inductive: Charging Plate
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`Ideal Definition of
`Efficiency
`
`Efficiency should be calculated as spatial average:
`
`“Total joules into the battery divided by total joules into the
`transmitter averaged over the charge area/volume for a charge
`cycle”
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`Where is Efficiency
`Measured?
`
`Efficiency Measurement
`
`Taken at the optimal spatial position and load power (5W, 4.2V @ 1.2A)
`
`h
`
`Li+
`
`Battery Charger
`
`Buck Regulator
`
`Synchronous DC-DC
`
`Wireless Receiver
`
`DC out
`
`Wireless Transmitter
`
`AC
`
`DC
`
`AC Adapter
`
`DC In
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`Efficiency
`Experiment
`
`1. Loosely-coupled, high-frequency wireless charger
`– EPC-9112
`
`– Similar to A4WP/Rezence Class 3
`
`– 6.78 MHz operation
`
`2. Closely-coupled, low-frequency wireless charger
`– BQ500212
`
`– Qi spec 1.1.2, Type A11
`
`– 110 ~ 210 kHz
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`Battery Model:
`2100 mA hr.
`
`Model determines load resistance,
`voltage and current test conditions
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`Total Energy
`27 kJ
`
`Energy required for typical (90%) charge-cycle of a
`2100 mA hr. battery
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`High-Frequency Wireless Charger
`Efficiency Experiment
`
`Power for a Wireless World
`
`Efficient Power Conversion
`Evaluation Kit EPC9112
`• 6.78 MHz operation
`• GaN switches
`• ZVS, Class D amplifier
`• NuCurrent antenna system
`compliant to Rezence class-3
`
`VDD
`8V – 36V
`
`Synchronous buck
`pre-regulator
`
`GaN
`
`Driver
`GaN
`
`Gate Drive
`& Control
`7.5V
`
`LDO
`
`5Vout
`
`6.78 MHz
`
`Zero Voltage Switching Class D Amplifier
`
`Rload
`
`EPC Device Board
`(Receiver)
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`Spatial Position
`Matters
`
`Efficiency vs. position for 10 ohm load
`“Open-Loop”
`
`Rload
`
`EPC Device Board
`(Receiver)
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`2 Configurations
`
`Resistive Load
`Configuration
`
`Battery Charging
`Configuration
`
`0V - >40V
`
`5.0V
`
`0V - 28V
`
`Rload
`
`EPC Device Board
`(Receiver)
`
`Rload
`
`Battery Charger
`
`Buck Regulator
`
`Synchronous DC-DC
`
`EPC Device Board
`(Receiver)
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Low-Frequency Wireless Charger
`Efficiency Experiment
`
`Power for a Wireless World
`
`Texas Instruments
`Evaluation Kit bq500212
`• 100 ~200 kHz operation
`• CMOS switches
`• Würth antenna compliant to
`Qi A11
`
`WPT Transmitter
`
`½ Bridge Driver
`
`Battery Charger
`
`Buck Regulator
`
`Synchronous DC-DC
`
`WPT Receiver
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`Spatial Position
`Matters
`
`Efficiency vs. position for 5 ohm load
`Full System
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`Efficiency Test
`Results
`
`• Qi is the most efficient
`system by design
`• Efficiency is impacted by:
`• Switching frequency
`• Antenna design
`• Spatial position / Coil-
`coupling coefficient
`• Maximum Power-
`Point Transfer
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`Battery Model:
`2100 mA hr.
`
`Total energy over 5% to 95% charge
`cycle: 27 k Joules
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World Real-World Efficiency
`
`65.7 kJ
`h= 39.6%
`
`43.8 kJ
`h= 59.4%
`
`27 kJ
`h= 100%
`
`Total Energy Efficiency
`Qi = 59.4%
`Rezence = 39.6%
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`Power for a Wireless World
`
`Conclusions
`
`• Real-world conditions must be used
`• Efficiency should be defined as a spatial average based on
`real-world use
`– “Total joules into the battery divided by total joules into the
`transmitter over one charge cycle”
`• Qi (low-frequency system) total charge efficiency ~60%
`• High-frequency total charge efficiency ~40%
`• A wireless charging standard that meets all market needs and
`use-cases must be dual-mode (resonant & inductive)
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

`

`
`
`Power for a Wireless WorldPower for a Wireless World
`
`Thank You
`
`Apple v. GUI Global Products
`IPR2021-00471, 472, 473
`GUI Ex. 2034
`
`

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