overview of wireless charging - ul · the mobile industry is transitioning to wireless charging...
TRANSCRIPT
© 2015 Underwriters Laboratories Inc.
OVERVIEW OF WIRELESS CHARGING
Wearables TechCon
March 11, 2015
Naomi Lee
Wireless Charging Program Manager
The mobile industry is transitioning to wireless charging solutions
giving users more convenience to no longer need to carry chargers
or wired power adapters while traveling.
There are three wireless alliances striving to be “The Wireless
Charging Standard” in the industry.
Wireless Power Transfer
2
WPC was established in December 2008 and Qi
low power specification was published in August
2009 based on Inductive power transfer.
PMA was established in March 2012 and PMA’s
Receiver specification was published in 2014
based on Inductive power transfer.
A4WP was established in March 2012 and
Rezence Baseline Specification was published in
2013 based on Resonance power transfer.
Wireless Power Transfer
3
Frequency of
Operation
100 – 205 kHz 200 – 350 kHz 6.78 MHz
Alignment Close
*Introducing Loose
Alignment, Q1/Q2
2015
Close Loose
Communication
Channel
In-Band with
Frequency of
Operation
In-Band with
Frequency of
Operation
Out-of-Band using
Bluetooth
NOTE: PMA and A4WP announced they will merge to
become one alliance by June 2015
Summary of differences in the three alliances.
Tightly coupled versus Loosely coupled
Tighter the coupling, higher the power transfer
efficiency, lower power loss and less heat produced.
Tight coupling is more advantageous for devices with
limited thermal budgets as smartphones or tablets.
4
Tightly coupled transmitter
and receivers have the same
size coils and smaller Z
distance than the coil
diameter. Both transmitter
and receiver coils have ferrite
shielding therefore less
EMI/EMF emissions
Tightly coupled versus Loosely coupled
Loosely coupled systems trade-off lower efficiency
power transfer with greater distance separation.
Loosely coupled systems have less power transfer
therefore a resonance circuit is needed to improve the
power transfer across distances.
In loosely coupled systems, a fraction of the power is
transferred to the receiver therefore there are higher
EMI/EMF emissions than tightly coupled systems.
5
Tightly coupled versus Loosely coupled
Loosely coupled coils operate at a larger distance or
operate with significantly different coil sizes.
6
Qi was the first of the three alliances for Wireless Power
Transfer. Qi‘s Wireless Power Transfer is based on
Magnetic Inductance with close alignment. UL Japan is
an accredited test lab for conformance tests. All
Interoperability tests conducted by a third party lab.
Wireless Power Consortium (Qi)
7
Mobile Conformance Tests (Receiver):
8
Wireless Power Consortium (Qi)
Test No. Mobile Testing Test Description
1 Conformance to Communications Interface Requirements - Load Modulation
2 Conformance to System Control Requirements - Digital Ping: Packet Timing
3 Conformance to System Control Requirements - Digital Ping: Packet Content
4 Conformance to System Control Requirements - Digital Ping: Signal Strength
5 Conformance to System Control Requirements - Digital Ping: Packet Timing
6 Conformance to System Control Requirements - Identification & Configuration: Packet Sequence
7 Conformance to System Control Requirements - Identification & Configuration: Packet Timing
8 Conformance to System Control Requirements - Identification & Configuration: Packet Content
9 Conformance to System Control Requirements - Power Transfer: Packet Timing
10 Conformance to System Control Requirements - Power Transfer: Packet Content
11 Conformance to System Control Requirements - Power Receiver: Reset
12 Conformance to System Performance Requirements - Guaranteed Power
Base Station Conformance Tests (Transmitter):
9
Wireless Power Consortium (Qi)
Test No. Base Station Testing Test Description
1 Conformance to Communication Interface Requirements - Load Modulation
2 Conformance to System Control Requirements - Selection phase
3 Conformance to System Control Requirements - Digital Ping: Power Signal Characteristics
4 Conformance to System Control Requirements - Digital Ping: No Response
5 Conformance to System Control Requirements - Digital Ping: Signal Strength
6 Conformance to System Control Requirements - Digital Ping: Termination
7 Conformance to System Control Requirements - Identification & Configuration: Packet Sequence
8 Conformance to System Control Requirements - Identification & Configuration: Packet Timing
9 Conformance to System Control Requirements - Identification & Configuration: Communication Error
10 Conformance to System Control Requirements - Identification & Configuration: Packet Content
11 Conformance to System Control Requirements - Power Transfer: Packet Sequence
12 Conformance to System Control Requirements - Power Transfer: Packet Timing
13 Conformance to System Control Requirements - Power Transfer: Packet Content
14 Conformance to System Control Requirements - Power Transfer: Packet Control
15 Conformance to System Control Requirements - Power Transfer: Termination
16 Conformance to System Performance Requirements - Guaranteed Power
17 Conformance to System Performance Requirements - Thermal Performance
18 Conformance to System Performance Requirements - Foreign Object Detection
19 Conformance to System Performance Requirements - User Interface: Object Placed
20 Conformance to System Performance Requirements - User Interface: Transfer in Progress
21 Conformance to System Performance Requirements - User Interface: Transfer Complete
22 Conformance to System Performance Requirements - User Interface: Fault
23 Conformance to System Performance Requirements - User Interface: Multiple Devices
24 Conformance to System Performance Requirements - User Interface: Limited Power
The PMA is another alliance striving to standardize the
wireless charging technology in the industry. PMA is also
based on magnetic inductance with close alignment.
Certification is based on conformance and interoperability
tests.
Power Matters Alliance (PMA)
10
UL Fremont is the Lead Lab
for PMA.
UL Taiwan is also an
accredited test lab.
Receiver Testing and Certification of PMA
• Receiver devices are tested to verify the device meets
the requirements of the PMA specifications on a
a customized Test Equipment which was
validated by UL.
• Measurements are conducted such as
coupling coefficient, efficiency, output
voltage and notification that charge is complete.
• Devices are also tested for interoperability functionality
with available transmitter devices to ensure the wireless
charging does not interferes with the device
performance.
Power Matters Alliance (PMA)
11
Receiver Conformance Tests:
12
Power Matters Alliance (PMA)
Test No. RX Testing Test Description
1 Detection - DC Magnetic Field Results
2 Detection - Alignment
3 Detection - Coupling Coefficient
4 Digital Ping - Engagement with Charging Surface
5 Digital Ping - Digital Ping Operation
6 Digital Ping - Output Voltage
7 Digital Ping - UCD Charging Notification
8 Identification - Stabilization Period
9 Identification - Message Correctness
10 Communication - Modulation
11 Charging Performance - Long Cycle Test
12 Charging Performance - Switch Load
13 Charging Performance - Efficiency
14 Power Termination - Regular End of Charge
15 Safety and Protection - Over Current Protection
16 Safety and Protection - Over Temperature Protection
Receiver Interoperability Tests:
More test cases will be added once validated by PMA.
13
Power Matters Alliance (PMA)
Test No. Interoperability Test Description
1 Scenario 1A - Engagement with Charging Surface - Basic Charging
2 Scenario 1A - Engagement with Charging Surface - Wired charging connected before placement
3 Scenario 1A - Engagement with Charging Surface - Wired charging connected after placement
4 Scenario 1A - Engagement with Charging Surface - Charging depleted battery
5 Scenario 1A - Engagement with Charging Surface - Low battery in misalignment condition
6 Scenario 1A – Engagement with Charging Surface - IUT temperature
7 Scenario 1A – Range of Motion Within Tx Operational Range
8 Scenario 1A – Range of Motion In and Out of Tx Operational Range
9 Scenario 1B – Touch Screen Performance
Transmitter Testing and Certification of PMA
• Transmitter compliance specifications are still in
development. Compliance test specifications to be
defined by end of Q1 2015.
• Conditional certification can be provided with
conducting transmitter interoperability tests with
available receiver devices. Once the compliance
specifications are finalized the transmitter must be
resubmitted for conformance testing for final
certification.
Power Matters Alliance (PMA)
14
Power Matters Alliance (PMA)
15
The A4WP or Rezence is another of the three alliances.
Rezence provides wireless charging with spatial freedom
and based on Magnetic Resonance with loose alignment.
This allows for flexible device placement and charging
through surfaces.
Alliance For Wireless Power (A4WP)
16
UL is working closely
with A4WP to become a
lab by Q2 2015. UL
Fremont will host the
next PlugFest at the end
of March.
Alliance For Wireless Power (A4WP)
Rezence Certification Program currently test both receiver
and transmitters manually. Rezence is working on an
automated testbed solution.
Certification has both Conformance and Interoperability
functionality tests.
17
Alliance For Wireless Power (A4WP)
18
Questions
19
Backup
20
Wireless Power Consortium (Qi)
21
Base Stations = Transmitter type difference summary
Base Station Description
Type A Based on a single Primary Coil
Type B Based on an array of Primary Coils
Mobile Devices = Receiver
Low power specifications transfers around 5W of power.
Power Matters Alliance (PMA)
22
Transmitter type difference summary
Tx Type Description
Power Class
0 (5W) 1 (10W) 2 (15W) 3 (20W) 4 (30W) 5 (40W) 6 (50W) 7 (70W)
PMA-1
Basic single coil design. Used
as a reference for testing.
Transmitter type installed in
Averna testers.
X
PMA-3 Enhanced performance single
coil design. Design to be rolled
out to all Starbucks globally. X
PMA-4 Enhanced performance single
coil design to support up to
Class 2. X X X
PMA-5 Enhanced performace multi-coil
design to support up to Class 2. X X X
Alliance for Wireless Power (A4WP)
23
PTU – Power Transfer Unit for BSS* 1.3
Class Type PowerTX_IN_MAX
(Maximum Input power to the resonator)
Min Category Support Min Value for Max # of device support
Class 1 2W 1 x Category 1 1 x Category 1
Class 2 10W 1 x Category 3 2 x Category 2
Class 3 16W 1 x Category 4 2 x Category 3
Class 4 33W 1 x Category 5 3 x Category 3
Class 5 50W 1 x Category 6 4 x Category 3
Class 6 70W 1 x Category 7 5 x Category 3
* BSS = Baseline System Specification
Alliance for Wireless Power (A4WP)
24
PRU – Power Receiver Unit for BSS 1.3
Category Type PowerRX_OUT_MAX
(Maximum output power of the PRU resonator)
Examples
Category 1 TBD BT headset
Category 2 3.5W Feature phone
Category 3 6.5W Smart phone
Category 4 13W Tablet, Phablet
Category 5 25W Small Form Factor Laptop
Category 6 37.5W Regular Laptop
Category 7 50W