Transcript Document

From the 380V DC Bus to sub-1V Processors:
Efficient Power Conversion Solutions
Stephen Oliver, V•I Chip Inc.
[email protected], +1 978 749 3256
SC’07, 11-14-07
SC’07, Reno NV, 11-14-07
Abstract
•
•
Without a major architectural review, data centers may consume 100 Billion kWhr by 2011. i
Additionally, inefficient power and cooling techniques may be the downfall of Moore’s law. ii
One efficiency improvement proposal iii is for the adoption of high voltage DC distribution to
enable the AC – 384V stage to be bypassed and the downstream sub-systems (or blades)
to be fed directly from the data center distribution busses. This paper represents a follow-on
step and proposes high efficiency, high power density power conversion solutions from the
HV bus down to processor and low-/medium- and high-power loads.
A baseline sub-system is established with a total load of 1320W:
–
–
–
•
6x processors (1V, 120A)
6x memory (1.5V, 50A)
Miscellaneous loads (12V, 12.5A)
•
Potential conversion steps considered are 380V-12V-1V and 380-48-1V with bus converter,
synchronous buck converters and factorized power regulators with sine amplitude
converters.
Efficiency, power density and annual electrical running cost comparisons are presented.
i.
ii.
iii.
“Report to Congress on Server and Data Center Energy Efficiency” (p56), U.S. EPA ENERGY STAR Program, Andrew Fanara, August 2, 2007
“The Invisible Crisis in the Data Center: The Economic meltdown of Moore’s Law”. Kenneth Brill, Uptime Institute, 2007
“DC Power for Improved Datacenter Efficiency”, Ton (Ecos), Fortenbery (EPRI) & Tschudi (Lawrence Berkeley National Labs), January 2007.
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•
2
‘Original’ Traditional High Power System (IBA)
AC
Rect., EMI
& Inrush
PFC
380VDC
AC-DC ‘Silver Box’
Regulated
HV DC-DC
48V
DC-DC
‘Brick’
12V
VRx
1.xV
VRx
1.xV Memory
CPU
Backplane
Motherboard
• AC-48VDC ‘Silver Box’ + 48-12V DC-DC ‘Brick’ + VRM/VRDs to loads
• As designed:
– ‘High’ efficiency (~65%), ‘small’ size, ‘cost effective’
– Powered 1.5-2.5V processors, few concerns over energy costs
– AC-12VDC SMPS & VRM efficiencies / densities improved
– IBA bus converters considered expensive and unnecessary
• As a result, use of a 12V-only bus increased
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• Over time:
3
‘Later’ Traditional High Power System (12V)
AC
Rect., EMI
& Inrush
PFC
380VDC
Regulated
HV DC-DC
12V
VRx
1.xV
VRx
1.xV Memory
AC-DC ‘Silver Box’
CPU
Motherboard / Blade
1.xV
VRx
1.xV Memory
Motherboard / Blade
CPU
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• AC to 12V ‘silver box’
• 12V distribution
• Synch Buck POLs to load voltages
VRx
4
12V Bus Concerns
• 12V bus is
– Established
– Proven
– Multi-sourced
• 12V Bus is also…
– Inefficient
• Distribution / connector losses
• Low efficiency synch buck POLs (especially for sub-1V loads)
due to duty-cycle limitations
– Expensive
• Large connectors, heavy bus bars, lots of copper, high electricity bills
• Only used in new systems due to incumbency and for legacy loads
(e.g. 12V disk drives)
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– Out of date
5
Efficiency Improvements
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• Higher voltage bus (380VDC* and / or 48VDC)
• Direct 48V-sub 1V conversion
• Provide 12V for legacy / low power loads
* “DC Power for Improved Datacenter Efficiency”, Ton (Ecos), Fortenbery (EPRI) & Tschudi
(Lawrence Berkeley National Labs), January 2007.
6
Revision #1: 380V to the Blade / Motherboard
AC
Rect., EMI
& Inrush
PFC
380VDC
HV
BCM
12V
VRx
1.xV
VRx
1.xV Memory
AC-HVDC ‘Silver Box’
CPU
Motherboard / Blade
• Silver Box  AC-“post-PFC” 380VDC
HV
BCM
12V
VRx
1.xV
VRx
1.xV Memory
CPU
– Reduces silver box size by >50%
– Eliminates distribution loss in system
(I2R loss at 380V is 0.1% of 12V loss)
– Minimize connector size and cost
• 380-12V conversion on the blade
– Minimize 12V distribution distance
Motherboard / Blade
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• 380V distribution direct to blade
7
HV DC-DC Conversion
• Bus Converter Module (BCM)
– Isolated, Unregulated
– Voltage transformer /
current multiplier
D
D
+IN
D
SAC
Control
D
+OUT
P
P
P
Cres
-OUT
D
-IN
D
D
P=Power Transformer
D=Drive Transformer
• Sine Amplitude Converter Topology
U.S. and Foreign Patents and Patents Pending
– ZVS, ZCS, >1Mhz switching frequency
300W @ 95.5%
330W @ 96.5%
• 1.1 in2 package (>1000W / in3)
– 1.28 x 0.87 x 0.26in
– 0.5 oz / 15 g each
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• 384:12V =
• 384:48V =
8
Revision #2: Direct 48V-to-load conversion
AC
Rect., EMI
& Inrush
PFC
380VDC
HV
BCM
AC-HVDC ‘Silver Box’
PRM
VTM 1.xV
PRM
VTM 1.xV Memory
48V
CPU
Motherboard / Blade
PRM
VTM 1.xV
PRM
VTM 1.xV Memory
48V
• Same 380V direct to blade
Motherboard / Blade
• 380-48V conversion on the blade
• 48-1.xV highest efficiency, smallest converter at the load
– Minimize 12V on-blade distribution loss
CPU
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HV
BCM
9
Direct 48V-to-Load Conversion
Pre-Regulator Module (PRM)
Voltage Transformation Module (VTM)
•
•
•
•
Non–isolated, regulator
ZVS Buck – Boost Topology
•
–
Performance
–
–
–
•
•
ZVS, >1MHz switching
•
320W in 1.1in2 package
Power Density >1,100W/in3
Efficiency
= >97% at 320W out
Input
Output
+IN
Performance
–
–
: Unregulated 48V
: Regulated (26-55V) VTM
•
•
ZVS, ZCS, >1Mhz switching frequency
Up to 100A in 1.1in2
>96% Efficient at 300W out
Input
Outputs
: Regulated 26-55V from PRM
: 0.8 - 55V, up to 100A (13 models)
+OUT
IL
D
D
+IN
D
SAC
Control
D
Cres
-OUT
D
-IN
ZVS B-B
Control
+OUT
P
P
P
D
D
P=Power Transformer
D=Drive Transformer
GND
•
GND
PRM + VTM = Isolated, regulated, voltage transformation direct to load
US and Foreign Patents and Patents Pending
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–
Isolated, voltage transformer
Sine Amplitude Converter Topology
10
Space-saving Powertrain – and no ‘Bulk’
• Direct 48V-to-load conversion with 2 V•I Chips
• PRM can be located remotely
– Increased space on motherboard / near load
– Reduced power dissipation at load
• Move POL Capacitance to input of VTM
– Reduce capacitance by 1/k^2
– Additional space and cost savings
Load
1uF
here
1,000uF
here
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Source
11
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Transient Response
12
Powertrain & Distribution Efficiency
•
•
High conversion efficiency and smallest footprint from 380V-load
Convert 380V to 1.5V, 200A
– Total “380V-to-load” Efficiency = 85.2%
• 96.5% x 97% x 91%
– Total PCB power component footprint = 4.4 in2 ( 4 chip solution )
• With fewer caps, smaller filters, smaller heatsinks
380V
PRM
48V
VTM
1.5V
200A
VF (48V)
VTM
•
Co-locate HV BCM & PRM, place only the VTM at the load
= highest distribution efficiency (I2R) and least space taken at the load
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HV BCM
13
Legacy, Low Power Loads
AC
Rect., EMI
& Inrush
PFC
HV
BCM
PRM
VTM 1.xV
PRM
VTM 1.xV Memory
48V
BCM
AC-HVDC ‘Silver Box’
380VDC
12V
VRx
xV
CPU
Low
Power
Loads
Motherboard / Blade
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• Step down from 48V to create 12V for legacy / low power loads.
• Simple unregulated DC-DC converter
Motherboard / Blade
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Systems Comparison
•
“System”
– Blade / Motherboard Content:
• 6 processors (1.0V, 120A ea.)
• 6 memory (1.5V, 50A ea.)
• Miscellaneous rails (12V, 150W total)
– Infrastructure:
• 30 blades / Motherboards
• Board impedance 1.5mΩ
• Rack distribution impedance 2.0mΩ
– Operation:
• Duty cycle = 65%
• Air conditioning = 50% efficient
• Electricity = $0.1028 per kWhr*
Systems:
–
–
–
–
[AC
[AC-384V]
[AC-384V] 48V
[AC 48V]
12V]
12V
1.xV
1.xV
1.xV
1.xV
(baseline)
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•
[…] = silver box
* Nevada industrial electricity price July ’07 ( http://www.eia.doe.gov/cneaf/electricity/epm/table5_6_a.html )
15
86
84
82
+8.7% pts
80
78
76
74
72
70
[AC - 12V] - 1.xV
[AC-384V] - 12V - 1.xV [AC-384V] - 48V - 1.xV
[AC - 48V] - 1.xV
• In all cases, adoption of higher voltage improves efficiency
• 380V in rack and 48V on blade / motherboard has highest efficiency
– +8.7% pts over baseline
• Improved efficiency 380V-Load means smaller PFC / EMI section.
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AC-Load Efficiency (%)
Efficiency Comparison: AC-Loads
16
450
400
173 W
350
300
250
200
150
[AC - 12V] - 1.xV
[AC-384V] - 12V - 1.xV [AC-384V] - 48V - 1.xV
[AC - 48V] - 1.xV
• Reduction of 173W per blade / motherboard vs. baseline
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Power Loss per Blade (W)
Power Loss (per Blade / Motherboard)
17
225
200
175
150
125
100
75
50
25
0
$202
[AC - 12V] - 1.xV
[AC-384V] - 12V - 1.xV [AC-384V] - 48V - 1.xV
[AC - 48V] - 1.xV
• 380V in rack and 48V on blade / motherboard has highest
saving ($202 per year, per blade / motherboard)
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Electricity Savings
per Year per Blade ($)
Utility Savings ( per Year per Blade / Motherboard )
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Conclusion
• 12V-only distribution systems have limitations in high
power computing applications
– Lower load voltages and larger load domain power
– Duty cycle limitation of synchronous buck conversion
– Increased I2R distribution loss
– Direct 48-to-load conversion offers high efficiency and small size
– Enable up to 8.7% pts efficiency improvement over 12V baseline
– Significant running cost savings
SC’07, 11-14-07
• Higher voltage (380V and / or 48V) distribution greatly
reduces distribution loss
19
References
•
•
•
“Report to Congress on Server and Data Center Energy Efficiency” (p56), U.S.
EPA ENERGY STAR Program, Andrew Fanara, August 2, 2007
“The Invisible Crisis in the Data Center: The Economic meltdown of Moore’s
Law”. Kenneth Brill, Uptime Institute, 2007
“DC Power for Improved Datacenter Efficiency”, Ton (Ecos), Fortenbery
(EPRI) & Tschudi (Lawrence Berkeley National Labs), January 2007
“Datacenter Power Delivery Architectures : Efficiency and Annual Operating
Costs”, Yeaman (V.I Chip), Digital Power Forum, September 2007
SC’07, 11-14-07
•
20
Thank you
Questions & comments?
SC’07, 11-14-07
Visit the V•I Chip booth (#832) for a live 380V-0.8V demo