power adapter design for 400 v dc power distribution in electronic systems
DESCRIPTION
This white paper describes the design of power adaptors for systems that distribute power using 400 V DC. The paper particularly considers telecom and data center equipment.TRANSCRIPT
Power adapter design for seamless interface of low voltage DC
equipment to 400V DC distribution
Maurizio Salato, VICORBJ Sonnenberg, Dustin J Becker, EMERSON Network Power
David E. Geary, UNIVERSAL Electric Corporation / StarLine DC Solutions
Table of content
• Power Adapter Characteristics of Interest• Telco site evolution options• Existing sites transition to 400V DC• Implications of power conversion location• Power Components for 380V Adapter and the Equalizer concept
• Architectural Matrixes• System safety and Harmonics considerations• Conclusions
Power Adapter Characteristics of Interest
• Location in the power stream: – The power drop box (busway or cable)– The rack power strip– 1U space “power shelf” within the rack– Plug‐in unit at “blade” level
• Electrical function and power conversion topologies
• Battery backup “equalization”
• Safety and protections
• Harmonics
Telco site evolution options
Many Transition Paths Possible
Today Next Step
-48VDC
Utility
Gen
-48V DC Power System
AC UPS
Facility AC Loads
Critical AC Loads
Critical 48V DC Loads
DCAC
Batt
Batt
380V DCUtility
Gen
Critical -48V DC Loads
DCDC
.Facility
DC Loads
ACDC
Batt400V DC Power
System
Facility AC Loads
Critical AC Loads
Critical 400V DC Loads
Local Generation
Source
● Paths forward with 400V DC for larger core sites:1. Greenfield with 400V loads (bulk or distributed 400V)2. Retrofit/expand -48V loads with 400V main plant (bulk)3. Greenfield with bulk 400V to distributed 400V/-48V
Existing sites transition to 400V DC 48V DC bulk equipment
380VDCSystem
48VDCEquipment
Rack
380VDCEquipment
Rack
380/48VDCConversion
+Secondary Distribution
380VDC cabling or bus way
48VDC cabling
The main power distribution from a 400V DC system is built with 400V DC bus way or cabling, directly to 400V DC enabled loads.
For loads requiring 48V DC inputs, a bulk 400V‐48V DC conversion replaces the “secondary distribution bay” and is located close to the loads to eliminate long 48V DC cable runs.
Existing sites transition to 400V DC 48V DC rack mounted equipment
The 400V DC distribution is extended close to the powered rack .
The options for location of the 400V‐48V DC conversion depend on the type of feeder used (bus‐way or cabling) and distribution inside the
rack.
Due to the relatively low power density of 48V DC powered racks, the conversion section is compact and can be located in a bus way plug‐in box, a
junction box on top of rack, inside the power strip itself or in a rack mounted shelf
Implications of power conversion location
LocationAdapter output supplies
Rack units management
System availability / redundancy
Busway or wire drop‐box Entire rack
Un‐qualified operator(SELV)
Fair(rack to rack)
Rack power shelf
Groups of units
Un‐qualified operator(SELV)
Medium(group to group)
Individual unit adapter Single unit
Qualified operator
(AC, 400V DC)Maximum
(unit to unit)
380V busway
Rack
Power Components for 380V Adapter
SAC
K=1/32
V V/32
I 32·ISAC
K=1/8
V V/8
I 8·I
ZVS BUZVS BO ZVS BB
BC K=1/32: high voltage bus converter, 260‐400V input, 32:1 ratio, 8‐12.5V output
BC K=1/8: high voltage bus converter, 260‐400V input, 8:1 ratio, 32‐50V output
ZVS BO: Zero Voltage Switching Boost regulator, 8V min. input, 55V max. output
ZVS BU: Zero Voltage Switching Buck regulator, 55V max. input, 8V min. output
ZVS BB: Zero Voltage Switching Buck‐Boost regulator, 32‐55V input, 20‐55V output
The Equalizer Concept
• Compliance to ETSI EN 300 132‐3‐1
• Regulate ONLY if voltage falls below normal operating range (365 V ± 15 V)
• 96%98% efficiency under normal operating conditions
• SELV Output
380V to 12V power components matrix
Load 12V Backplane HDD VRMsSource Range VOUT 12V ± 2% 12V ± 4% 12V ± 35%
VIN [V] 11.75‐12.25 11.5‐12.5 8‐16
Regulated 384V ± 1% 380‐388
Semi‐regulated 380V ‐8% +3% 350‐390
ETSI EN 300 132‐3‐1EMERGE >3ms
380V nom 260‐400
12V LoadsPower distribution
BC K=1/32
BC K=1/8 & BU regulator BC K=1/32 & BO equalizer
380V to 48V power components matrix
Load 48V Backplane ETSI 48V FPASource Range VOUT 48V ± 2% 48V nom 45V nom
VIN [V] 47‐49 36‐60 32‐60
Regulated 384V ± 1% 380‐388
Semi‐regulated 380V ‐8% +3% 350‐390
BC K=1/8 & BO equalizer
ETSI EN 300 132‐3‐1EMERGE >3ms
380V nom 260‐400
BC K=1/8 & BB regulator BC K=1/8 & BO equalizer
48V LoadsPower distribution
BC K=1/8
Adapter power architecture, peak efficiency and density vs. Distribution Ratio (DR)
94%
98%
0.8 3 5
+ +EqualizerBus Conv. Bus Conv. RegulatorBus Conv.
Power conversion peak efficiency
Power components
97%
96%
95%
400 (25)
1200 (73)
2000 (122)
Power component density(components only)[W/inch3 – (W/cm3)]
+
Equalizer
Bus Conv.
Regulator
OR
Non‐equalized output
Equalized outputRegulated output
Safety and Operators protections
Isolated, floating supply, 200V max withrespect to hearth.
Mid‐point resistive grounding early‐detectionsystem for isolation faults.
Safely sustains up to 500V operatinginput to output voltage differential.
Low voltage secondary in UL/CSA 60950 qualified SELV range.
The SAC converter galvanically isolates the 400V DC and the low voltage distribution systems
Harmonics• AC distribution systems are affected by higher order harmonics
generated by the interaction of AC‐DC converters. – the impact of high THD on AC distribution systems can affect up to
59% of the installed wiring capacity, leading to significant higher operating costs or even hazards.
• Bulk power systems and DC‐DC converters generate harmonics that typically start at the switching frequency of the considered converter, therefore a much higher frequency than AC‐DC converters.– Passive filtering for this type of spectrum is usually effective, small and
avoids low frequency beats that may result from the interaction of asynchronous DC‐DC converters. Moreover, filter size allows effective integration within the adapter enclosure.
Conclusions• 400V DC distribution systems offer quantifiable advantages not only for new telecom
and/or datacenter facilities, but also for upgrades of existing ones. • Power component‐based architectures for power adapters have been discussed and
analyzed.• The proposed locations leverage the space available within equipment racks or within
racks’ rows, making maximum use of available space and enabling maximum racks density as far as equipment loads.
• Best location of power adapter for use with legacy loads depends on user preference based on the following criteria :
– Safety– Availability– Efficiency– Ease of harmonics content elimination– Cabling size
• For high density loads, the best system architecture from efficiency , reliability and space savings standpoint is a direct 380VDC connection to the motherboard with on‐board 380VDC‐48VDC bus converter and direct 48V to processor/memory factorized power system.