Gentlemen,
The first set of choices will need to be the overall goals for
the system to meet a 10+ year life expectancy in anticipation of changing
conditions. After the overall goals are elaborated, argued and voted on, the
detailed design proposals can be examined against that criteria.
Bob
From: upamd@xxxxxxxx
[mailto:upamd@xxxxxxxx] On Behalf Of LEI / Rene Koch
Sent: Thursday, July 08, 2010 7:17 PM
To: Edgar Brown; Per Hassel Sørensen
Cc: upamd@xxxxxxxx
Subject: Re: SV: Potential Goals of the group for discussion
Dear Edgar and
Per,
Very good, I
think we're getting somewhere.
I see a problem
though with kelvin sensing, when it will be based on the load's feedback
setting. It will be very hard to get a stable feedback loop if the sensing is
in the active feedback loop.
Therefore I
think we should have an active feedback loop (1st loop) that satisfies
stability needs and a second loop that could be driven by the load.
The first loop
should be based on the contacts of the power supply, which creates a stable output
and then the second loop, by the kelvin sensing or communication as proposed.
This way we establish a very simple high/low signal on that sensing that just
requests more or less voltage/power from the power supply, regardless how high
that is; the response to that signal however will have to be slow (<1kHz) in
order not to interfere with the 1st feedback loop.
Edgar raised
another important point, I think, and that is single fault conditions.
I think the
connector should be designed in such a way that the communications/feedback
link makes contact before the actual power. This practically means that it
would be almost impossible to have a feedback signal, requesting power while
there is a short between any two connections. The feedback will have a reasonably
high impedance, compared to that of the power lines, which looks like a short
initially due to the presence of a discharged large electrolytic capacitance.
Finally I think
we are actually moving away from the possibility of having communication over
the DC power lines. So we would need at least a 3 wire connection.
Best regards,
Rene Koch
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Edgar
Brown <edgar.brown@xxxxxxxxxxxx>
Sent by:
upamd@xxxxxxxx
07/09/2010
08:06 AM
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To
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Per
Hassel Sørensen <phs@xxxxxxxxxxxx>
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cc
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"upamd@xxxxxxxx"
<upamd@xxxxxxxx>
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Subject
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Re:
SV: Potential Goals of the group for discussion
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Per Hassel,
I think we are _mostly_ in violent agreement. I now think that an analog
modality would be feasible and cost-effective, as long as it is a
simple/feature-less implementation. A good example is kelvin-sensing. As long
as there is trickle power, the adapter can sense the presence of a load and
slowly increase the voltage until the sensing lead reaches a specific voltage
range. That way the adapter does not need any further information from the
load. The adapter only has to track the feedback signal adjusting its output to
remain in the acceptable range. Alternatively, the current or impedance on the
'kelvin' lead could indicate the "power-class" of the load.
Note that any analog DC alternative (that I can think of) has the problem of
guaranteeing that the adapter does not become a hazard when two or more random
terminals in the connector are shorted together.
Regarding power, I agree on the approach of making the marking presence and
location a mandatory part of the standard. This can be complemented with LED
colors and patterns. A user could easily become accustomed to an adapter's fast
blinking red LED, just beside the power sticker, indicating that it cannot
provide enough power for the connected device. (Or a steady yellow indicating
that the user could be better served by a higher-power adapter.)
I do see another conflict that has been brewing here:
- two wire adapters/plugs, vs. three or four wire plugs.
Edgar
On Jul 8, 2010, at 7:10 PM, Per Hassel Sørensen wrote:
Edgar,
I agree that it
is detrimental if we have some various adapter classes, but:
I believe it is
almost impossible to not have incompatible combinations of adapters and devices
due to power requirements. The biggest cost factor for a mains powered adapter
is the power rating. It is also a weight and size factor affecting portability
and usage. I don't think people will accept cost, size or weight of a 130W
UPADM adapter to power a device like a portable radio or charge a micro RC
model helicopter. I think this is not a big issue if handled properly.
With a good
UPADM standard, it should be the possible to use any UPADM adapter as long as
it supplies the minimum power needed for the device. Everybody (Almost)
will understand that adapters need to come in different sizes. This is not
difficult as long as we keep adapter power rating the only variable the user
has to think of. It could be part of the standard that power rating of adapter
and consumer is easy to locate, is concise and has a common labeling. And
imagine a sales situation where someone walks into a store in need for an
adapter: The 130W 'brick' will always work, (un)fortunately (for the store), it
is the most expensive one.
To save cost on
the consumer side the UPAMD could support a basic analog mode. Imagine having
two separate communication wires in the UPAMD cable. When in analog mode they
are used for sensing a simple analog network in the consumer. Certain
properties (resistance, zener diode voltage etc.) is detected by the adapter to
select correct output voltage, current limits etc. Further, as a
transition solution, a UPAMD adapter cable with built-in analog network could
be built for a very low cost to be used with legacy equipment lacking built-in
UPAMD support. This way existing equipment can use the new adapter.
For more
advanced consumers the UPAMD would use the two communication wires for duplex
communication overlayed (or time multiplexed) on analog voltage feedback (aka
'Kelvin clips') for reduced cable cost, better regulation and other benefits as
stated in my previous mail.
This way a full
digital communication is present in every UPAMD adapter from the beginning,
without requiring a major revision for purely analog devices. And every UPAMD
adapter will work with all devices, as long as the power requirements are met
as described above.
Per Hassel
Fra: upamd@xxxxxxxx på vegne av Edgar
Brown
Sendt: to 08.07.2010 17:43
Til: LEI / Rene Koch
Kopi: upamd@xxxxxxxx
Emne:
Re: Potential Goals of the group for discussion
Rene,
I see two conflicting goals in removing communications from the requirements:
(1) universality (one adapter fits all) and (2) low-cost (a.k.a. analog)
simplicity. Although a properly designed analog solution can nearly always be
the lowest _manufacturing_ cost one. It would probably be the most complicated
in terms of flexibility. As an analog and digital designer, I am always
confronted on where each technology fits best. I can clearly remember the cases
in which, after a grueling analog design has been put together, I have wished
to have gone digital instead. While the converse is rarely true.
These are the issues as I see them:
- A single plug fits all: If a UPAMD plug is present in an adapter and a
device, we want the consumer to correctly assume that the two can be plugged
together. Having a class of adapters that would not power some subset of
devices would be very detrimental to this goal (this also applies to power
levels, B.T.W.). This is also one of the strongest arguments against the highly
non-standard and irritating family of barrel connectors.
- Providing enough flexibility through analog means, although possible, would
_probably_ complicate the circuit enough that a comparable digital solution
would end up being cheaper in the short (and long) term. (And clearly cheaper
from a design stand point.)
- A properly designed (and adopted) standard would create industry demand for
the right low-cost semiconductor solutions. As a sample, take a look at the
prevalence of ARM cores in TI's family of PMBus PWM power controllers. An ARM
core would be overkill for our intended application, but it is not out of the
question in the mid-term. A power supply that has to satisfy multiple
requirements, such as power-factor correction, low-power consumption, stand-by
modes, etc., presents enough functionality that an all-encompassing integrated
digital solution would probably be preferable.
And while writing this I thought of a way to accomplish some of the conflicting
analog requirements. A simple feedback mechanism, in which the device requests
power from the UPAMD through a simple lower/higher analog signal (essentially a
slow remote regulation loop) could satisfy some of these conflicting
requirements. An AC signal (e.g., AM-modulated voltage feedback) can close the
device-adapter loop. Only requiring simple diode/resistor/capacitor circuitry
to extract the return feedback signal. And this would not even require extra
wires in the connector. This choice would somewhat complicate any
communications between adapter and device, but it still can be done with
decades-old modem technology.
Regarding 'greening' technologies. Although it is true that large equipment is
the easiest target for conservation efforts, do not underestimate the amount of
power being wasted on tens of unused but plugged adapters in each home and
thousands in each office building. Also don't underestimate that any progress
towards these types of standard would also ease the development of equivalent
standards in directly-plugged AC devices. Any progress to be made in removing
power through greener adapters I believe to be worthwhile. Especially in a
standard that we hope would be still useful a few decades into the future.
Edgar Brown
On Jul 7, 2010, at 4:51 AM, LEI / Rene Koch wrote:
I think I sense that extended communication is wishful; I agree that would be a
nice addition for the future.
However, I still have cost concerns to this when we absolutely need this
communication in order to get some power from the supply.
Therefore I would vote for a solution that would not restrain communication in
any way, but that we also find a way for simple and low-cost power adapters to
be used, without communication ability.
Adding smart-grid integration would make sense, although this, at this time, is
more focussed on big power users like aircons, water heaters and other luxury
type of products. When the device is smart enough and goes to a power down or
standby mode whenever possible, there is no need for smart-grid to intervene, I
do not think that EISA 2007 will go so far that even laptop computers printers
and networks will have to go down when actually being used; I think it will
remain at aircons, heaters, waterheaters, (dish)washing machines and
(public)lighting; most of this type of equipment consumes a lot more than what
the adapter in question can provide.
It is not difficult anymore to get below 100mW in stand-by, it is just a matter
of price at this time, in a couple of years I foresee most adapters to be able
to draw less than 50mW in no-load.
This is a great achievement from most power supply manufacturers and power/PWM
IC design houses. Destroying that by adding another 100mW or more, just to
listen or communicate in order to go down to an overall power down for a period
in time does not make sense to me.
Would the overall energy usage really bring us below 50mW? If so, is this
enough to justify the extra waste that we add? (controller, manufacturing of
that controller, distribution of that controller, extra wires for the communication
needs).
Ecodesign in Europe already announced to be looking at the total picture,
including design, manufacturing, testing and distribution involved in putting
any product to market. (total green concept or cradle-to-grave)
As I mentioned in one of my earlier comments, having a power supply that could
also perform as a bridge to Power Line Communication or Smart-grid could be a
great addition and would make sense in the future when the different types of
network communication will get more and more integrated into each other to
increase and secure the total available bandwidth.
Best regards,
Rene Koch
Some additional suggestions regarding "green" capabilities.
A) Support for Load Shedding / Demand Response / Dynamic Demand
functionality.
The power adapter-to-device communications should support primitives
for demand shaping, incorporating mains-side interface/definitions to
support the applicable protocols and standards. To reduce cost, and
avoid restrictions over the multiple mains standards, the specific
load-shedding support should remain optional.
Use cases:
(1) The utility generates a load-shedding request that gets coupled
into the home network. Compatible UPAMDs (the ones implementing a load-
shedding protocol mains-side) send the request across to the connected
device. The connected device responds by modifying its power
requirements or removing them altogether. (The user could set the
power-saving settings similarly to existing battery-conservation
settings in laptops).
(2) The user requests device charging only during off-peak (e.g., low-
cost) utility periods. A home-based controller instructs compatible
UPAMDs to provide power only during those periods (note that this
might not require intervention from the device side, i.e., forced
power-shedding.)
(3) The user connects an specific UPAMD (to be used with a different
device) to a computer and configures its power-saving capabilities
through a local program or web page. A real-time clock inside the
UPAMD indicates at what times it will provide power to the attached
device.
Possible applicable standards: IEEE P2030, IEEE P1547.8, ISO/IEC
14543-3 (KNX), IEEE 1815, IEEE P1901, IEC 61334, ITU G.9972.
The most relevant standards seem to be the ones from the KNX
association.
Industry standards: HomePlug Command & Control, HomePlug GreenPhy, http://www.prime-alliance.org/
Related technologies:
load shedding lighting ballasts: http://www.lrc.rpi.edu/researchAreas/pdf/LoadShedBrochureNYS.pdf
,
home control: http://www.Insteonsmartgrid.com/about-us.html )
B) Sleep capability requirements.
To reduce power consumption, the mains-side of the UPAMD should
disconnect itself from mains power for pre-defined periods of time
(e.g., 5 sec, 10 sec or even longer). When not in use, the excess
capacitive power reserve should be able to power the UPAMD electronics
for a considerable period of time. The mains-side switcher can be
turned-off (for several seconds) in those conditions providing near-
zero power consumption. (A slow-blinking LED, for power reasons, can
indicate this condition.) This would make it much easier to satisfy a
<100mW standby mode.
Alternative 1: If trickle power is provided to the powered device, the
UPAMD only powers-up to keep trickle-power regulation.
Alternative 2: The UPAMD only provides trickle-power to the connected
device for a brief period every n seconds.
Alternative 3: The sleep period becomes longer if the device has not
been used for an extended period of time (a reserve super cap can
provide sleep power under such conditions).
Note that EMC issues can arise due to this start/stop condition, and
additional restrictions (e.g., a soft start-up envelope) might be
required to avoid these.
Cost considerations: given that some intelligence is to be required to
provide the communications layer, the additional controls required to
implement this capability would be minimal. Alternative
implementations (e.g., timers, or voltage comparators) can allow for
further cost reductions.
EB