IEEE Power Electronics Magazine - March 2017 - 23

^W h, P LONG IDLE is measured power consumption in long
The EC Ecodesign Directive for computers also specifies an 80 PLUS standard minimum in its requirements
idle mode ^W h, P SHORT IDLE is measured power consumption
(617/2013) [9]. But new programs are specifying higher
in short idle mode ^W h, and T OFF, T SLEEP, T LONG IDLE, and
levels; the latest version 3 draft of
TSHORT IDLE are mode weightings as
the ENERGY STAR computer server
specified in [8, Table 3].
program specification proposes 80
To be compliant, a computer's calPLUS Platinum efficiency, and the
culated TEC must be lower than the
What is certain is that
CEC is requiring 80 PLUS Gold IPS
energy allowed in the California stanthe efficiency regulaefficiency for workstations in 2018.
dard [11]. Early attempts to meet the
proposed standard were hampered
tions landscape will
by IPSs with poor efficiency at veryRegulations Indirectly Impacting
continue
to
change
as
low-power mode levels. A demonstraPower Supply Efficiency
tion of a compliant computer using an
Whereas the programs and standards
components and design
IPS designed specifically to provide
mentioned previously specifically tarimprovements deliver
high efficiency at the required power
get power supply efficiency, other prolevels was demonstrated at an April
grams indirectly affect power supply
higher levels of power
2016 CEC stakeholder workshop [12].
efficiency by addressing consumption
conversion efficiency.
The custom-designed 300-W IPS conin an application's standby or off
sisted of a highly efficient high-power
modes. A prime example is the EC
switching power supply coupled with
Ecodesign Directive requirements for
a highly efficient low-power switchstandby- and off-mode electric power
ing power supply. The computer used cost-effective, offconsumption of electrical and electronic household and
the-shelf components. The IPS automatically switched
office equipment (1275/2008, with amendment 801/2013) [10].
outputs from one supply to the other, depending on load
A horizontal standard, this program limits off- and standbyrequirements. The demonstration reinforced the fact that
mode power consumption for a wide range of unrelated
in addition to improved computer design, conformance
office and home products. Meeting the current maximum
was unlikely without improved power supply design.
standby power consumption limit of 0.5 W would be impossible with a power supply that was inefficient at very low
loads [i.e., the linear-based EPS in Figure 1(a)].
What's Next?
In recent years, the energy-consumption-limiting TEC
What is certain is that the efficiency regulations landscape
approach, mentioned previously, has found its way into
will continue to change as components and design
efficiency regulations. Although TEC specifications do
improvements deliver higher levels of power conversion
not specifically address power supplies, they demand
efficiency. Keeping up with revisions to current programs
high-power-supply efficiency for a wide operating range,
as well as new product program requirements can be
limiting an application's energy consumption in very-lowpower operating modes (i.e., off, standby, and idle). The
focus on these lower-power modes places performance
Maximum No-Load Power Consumption
pressure on the power supply to maintain high efficiency
0.6
from a 100% load down into the single-digit load area. Efficiency programs and standards that currently use TEC
0.5
metrics include ENERGY STAR (set-top box, computer,
and displays), Ecodesign Directive (computer), and soon,
0.4
CEC Appliance Efficiency Regulations (computer). The
CEC recently approved mandatory computer regulation
0.3
harmonizes with the voluntary ENERGY STAR computer
0.21
0.2
program version 6.1 metrics but with tighter limits. Both
0.15
requirements focus on energy consumed during nonactive
0.1
computing modes.
A computer's annual energy consumption (E TEC) is
0
calculated using the following:
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70
-

No Load (W)

E TEC = (8760 ' 1000) # (P OFF # T OFF + P SLEEP # T SLEEP
+ P LONG IDLE # T LONG IDLE + P SHORT IDLE # T SHORT IDLE),
-

where P OFF is measured power consumption in off mode
^W h, P SLEEP is measured power consumption in sleep mode

Nominal Power (Watts)
CoC v5 (Tier 2)
Ecodesign Dir. (Lev. V)

U.S. DOE 2016 (Lev. VI)
Previous U.S. DOE (Lev. IV)

FIG 4 The ac-dc single-output no-load power consumption
requirements curves.

March 2017

z IEEE PowEr ElEctronIcs MagazInE

Table of Contents for the Digital Edition of IEEE Power Electronics Magazine - March 2017