hvdc power supply system implementation in ntt group … · c reduce construction achieve both...

1 Copyright © NTT

NTT Confidential

2015.2.3

Toru Tanaka NTT Energy and Environment Systems Laboratories, Nippon Telegraph and Telephone Corporation, Tokyo Japan

HVDC power supply system

implementation in NTT Group and

next generation power supply

The Second International Symposium on Open Energy Systems

2 Copyright(c) 2015 Nippon Telegraph and Telephone Corporation

Outline


1. Introduction

2. Advantages of HVDC

3. NTT group’s strategy and technical requirement

4. Application of HVDC

Next generation power supply system

1. System topology

2. Study of voltage levels

Summary


Musashino R&D center Tsukuba R&D center

Introduction of

NTT energy and environment systems lab. We, NTT Group, is changing from only being telecom company to that which

promotes global cloud business. Our lab promotes environmental load

reduction of NTT group.

We aim to achieve sustainable and low-carbon society.

NTT groups

Keihanna

building

Yokosuka

R&D center

Atsugi R&D center

Information Network Laboratory Group

Access Network Service System Lab.

Network Technology Lab.

Network Service System Lab.

Energy and Environment Systems Lab.

Science and Core Technology Laboratory Group

Service Innovation Laboratory Group

Consulting, design,

and maintenance for

building and power

supply system

Power supply ⇒DC power supply

Air conditioning ⇒ DEMS

EMC ⇒ Thunder and noise

Materials ⇒ Recycling and prolonging

environmental impact assessment

Our lab’s fields and technology


DC power supply system for telecom buildings

Battery

48 V DC power supply system

DC 48 V 1 2

Conversion STGs=2→simple

Rectifier ICT equip.

Telecom facilities

6600 V Tr

Battery Battery

RF PDF ICT ICT

RF PDF ICT ICT

DC Line AC Line

Tr: Transformer

RF: Rectifier

PDF: Power Distribution Frame

NTT has been introducing DC power supply system for many years because

DC system is highly reliable and efficient. Conventionally, DC -48 V is used as

power bus.

Rectifier Power Distribution Frame

AC

DC

DC

DCCPU

Generator

DC 48 V


5

Increasing power consumption

Power consumption per rack Increase in data-center market and

power consumption

Alaxala AX6708S Cisco CRS-1

Exhibition: Fact-finding 2012 version of a datacenter market and power consumption

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000Market [Milionn Dollar]

Power consumption [Gkwh]

Sever

(1U, blade,

custom)

Rooter

(Core, Edge)

Sever

(2U, Lo-end)

Storage

Work station

Tape storage

Po

wer

co

nsu

mp

tio

n

per

rack [K

w/r

ack]

Power consumption per rack of ICT equipment is increasing due to capacity enlargement of ICT equipment. Also, scale of data centers is increasing. Therefore, reducing power consumption is important.

HP Blade System c7000


Energy Consumption of NTT Group

- NTT Group’s business activities consume electricity of about 8.5 billion

kWh per year.

- Since 2008, energy consumption of each year is almost same. However,

electrical fee has been increasing.

- Energy saving is important issue because “CLOUD” and “IP” services are

spreading widely and they consume large amount of electricity.

0

20

40

60

80

100

1990 2000 2003 2009 2010 2011 2012 2013 2014

Ene

rgy

con

sum

pti

on

[

bill

ion

kW

h] ?

8.52 billion

kWh

¥

This is equivalent to 1% of total power

consumption in Japan

10

8

6

4

2

0


Battery

AC power supply

Battery

DC power supply (-48 V)

Battery

HVDC power supply

Building cost

can be reduced

-- Lower installation cost

(small diameter cables

are available)

-- Flexible installation

AC 100

~200 V DC 48 V

DC 380 V

-- Higher efficiency

(fewer conversion stages)

-- Higher reliability

(battery direct connecting

Total losses

can be reduced

Conversion STGs=4 Complicated Conversion STGs=2 simple

UPS ICT equip. Rectifier ICT equip.


Conversion STGs=2

1 2

DC

AC

AC

DC3 4

MB AC

DC

DC

DC

1

AC

DC2

DC

DCMB

1 2

AC

DCDC

DCMB

HVDC power supply systems supply DC 380 V to ICT equipment

-- HVDC systems have fewer conversion steps than AC systems.

⇒higher efficiency and higher reliability

-- HVDC systems can reduce current compared to 48-V systems.

⇒use of thinner power cables, which reduces construction costs

HVDC (DC 380 V) power supply system


Advantages of HVDC system

-- Higher efficiency

(fewer conversion stage)

-- Higher reliability

(battery direct connecting)

-- Space saving -- Low cost

Energy consumption: 10% savings Reliability: 10 times higher

Space: 30% savings Cost: 50％ savings

１ 2

3 4


High efficiency １

■Total efficiency from battery to ICT unit

Efficiency

difference:

12.8％

② HVDC power supply system

Total efficiency:

92.12％

(DC 260 ~ 400 V)

98%※1 （ Load ratio 80% ）

94% Battery

Rectifier DC 380 V

PDF

86

88

90

92

94

96

0 20 40 60 80 100

▲

▲

▲ ▲ ▲ ▲ ▲ ▲

Load [%]

Eff

icie

ncy [%

]

HVDC RF system AC UPS system

Operating point of

HVDC RF

Operating point

of AC UPS

① AC power supply system with redundancy (double)

Total efficiency:

79.34％ 88% （Load ratio 40%）

98%

（With transformer）

(AC 200 V, AC 100 V)

AC

92%

UPS PDF

88% ( Load ratio 40% )

UPS PDF

98%

（With transformer）

PSU Mother-

board

PSU Mother-

board

HVDC system include high-efficiency components (RF, PSU) and it

has simple configuration.

Total efficiency of HVDC system is improved to 92% or more .

※2NEDO Green IT data ※1 Latest RF

※2


High Reliability ２

<reference> H. Ikebe, N. Yamashita, R. Nishii; GREEN ENERGY FOR TELECOMMUNICATIONS; Intelec2007

AC power

supply with

UPS

DC power

supply

Field data

UPS: about 10,000 units, DC power supply about 23,000 units

No

n-o

pe

rati

ng

rati

o

DC: No failure DC: No failure

We have operated many power supply systems for many years.

■ From design reliability calculation, DC systems are 10 times more reliable

than AC power systems.

■ High reliability has been verified by evaluating data in field.

Battery

DC

AC

AC

DC

SW

AC power supply

Battery

DC power supply

AC

DC


Space saving ３

Transformer

UPS

Battery

PDF

1800 m

m

1800 m

m

1000 m

m

900

mm

98.6 m2

11

Space saving

▲31% (▲ 30.2 m2)

Battery

PDF

RF

Transformer

6000 mm

6400 mm

5600 mm

180

0 m

m

900

mm

645 m

m

68.4 m2

500-kW system

Back up time: 10 min

5600 mm

6800 mm

4800 mm

7200 mm

When we introduce HVDC system, we can achieve about 30%

reduction in space.


Reducing construction costs（thin cable）４

DC 48 V 325 mm2 X 20 cables

DC 400 V 200 mm2 X 2 cables

Number of cables between battery and rectifier for

100-kW system

Cross-sectional area of cables is one-tenth compared to DC -48 V

system. Thus, HVDC system can reduce construction costs by –

ensuring air-flow space under floor – reducing costs of cable, and

improving its distribution.

BATT

BATT

ICT eq.

ICT eq.

DC 48 V rectifier

HVDC rectifier

DC -48 V

HVDC

DC -48 V DC -48 V

HVDC HVDC

DC 48 V

DC 400 V

Air flow

Air conditioning efficiency

PDF

PDF


Battery

AC power feeding

AC 100

~200 V

UPS ICT equip.

DC

AC

AC

DCMB

AC

DC

DC

DC

When voltage is higher, we can reduce power loss but safety measure costs

increase. Also, we have been using DC 380 V in UPS and PSU, so we can use those

components for DC 380 V. Furthermore, 380 V is created by piling up 168 battery

cells.

Why 380 V？

About DC 380 V

DC 12 V,

48 V etc

Battery


AC

DCMB

DC

DCDC 380 V

DC 12 V,

48 V etc

HVDC power feeding

AC 200 V

AC 200 V

× × BATT: 168 cells

(24 cells × 7)

Nominal Voltage

168 cells × 2.0 V

= 336 V

Working Voltage

168 cells × 2.23

～2.25 V

=374.6～378 V

DC 380 V


Issues of HVDC system

Safety

Electrical stability Line-up of power

equipment

Line-up of ICT

equipment Standardization

Technical issues

Promotion issues


Earthing with electrical safety

1

5

To ensure human safety, we adopted earthed high-ohmic mid-point.

This system limits human touch current in case of human error.

System with earthed negative line System with earthed high-ohmic mid-point

0V

+380 V

ICT equipment

-190 V

+190 V

ICT equipment

Current flow Current flow

Human touch current: about 270 mA Human touch current: about 10 mA

270 mA corresponds to Level IV in IEC

60479

It indicates High risk to human body

10 mA corresponds to Level I in IEC

60479-1

It indicates Low risk to human body This system is defined by ETSI EN 301 605


Human touch current (IEC standard)

Reference：IEC/TS 60479-1 figure20,22

IEC: International Electrotechnical Commis

10

100

1000

10000

0.1 1 10 100 1000 10000

0.1 1 10 100 1000 10000

100

1000

10000

10

［ｍＡ］

［ｍｓ］

Ⅰ Ⅱ Ⅲ Ⅳ

ＡＣ

ＤＣ

Body current

Dura

tion o

f curr

ent

flow

10

100

1000

10000

0.1 1 10 100 1000 10000

0.1 1 10 100 1000 10000

100

1000

10000

10

［ｍＡ］

［ｍｓ］

Ⅰ Ⅱ Ⅲ Ⅳ

ＤＣ

Body current

Dura

tion o

f curr

ent

flow

ＡＣ

10 mA 270 mA

Safety level

I: Electrification that humans cannot feel

II: Humans feel pain but there are no problems physiologically

III: Muscle cramps and breathing difficulty occurs: dangerous.

IV: Ventricular fibrillation occurs: very dangerous.


Socket and outlet

Plug: unlock Plug: lock

Switch: ON Switch: OFF

Mechanical interlock

(Combination of permanent magnet and mechanical contacts)

NTT Facilities collaborates with

Fujitsu component, Ltd.


Suppressing voltage fluctuation

New fuse for HVDC

Fuse for 48 V

New fuse and PDF for HVDC

We can evaluate effect of voltage fluctuation at ICT equipment when short

circuit occurs.

We developed fuse and PDF to suppress voltage fluctuation

Capacitor Voltage [V

]

Time [ms]

320

340

360

380

400

420

440

460

480

500

520

-0.1 0 0.1 0.2 0.3 0.4 0.5

他装置入力端電圧（V

)

時間（ｍｓ）

従来品

開発品

Voltage variation of normal operation side

Duration of

over 400 V is

under 50 us.

Conventional

product

Development

product

AC 200 V => DC 380V

Voltage fluctuation

occurs


Lineup of HVDC power supply components

Rectifier:

100 and 500 kW

PDF:

Fuse type and

MCCB type

Outlet:

Bar, plug. and

connector for

HVDC

Converter:

Convert DC 380 V

to DC 48 V or AC

100 V

Grounding:

Mid point

grounding

system

We completed development of power-supply equipment


Worldwide expansion of HVDC

HVDC has been expanded as DC 380 V power supply system worldwide

20 Telecommunication

building Datacenter Micro grid, etc

SAP

DC 380 V

Nextek

DC 380 V

Syracuse

University

DC 380 V

Duke

Energy

DC 380 V

Intel

DC 380 V

Clustered

Systems

DC 380 V

NZ

telecom

DC 340 V

China

telecom DC 240/380 V

IBM 380V DC

China

Mobile

DC 380 V

European

telecom

DC 380 V

Netpower Labs AB (several sites)

DC 350/380 V

UPN AB DC 350/380 V

France

telecom

DC 380 V

Univ. of

California

DC 380 V

The graph is modified based on NTT Facilities inc’s data.

IBM DC 380 V

Korea DC 300/380

V

Some IT

manufactures

DC 380 V

ABB DC 380 V

France

telecom

DC 380 V

Steel

Ocra

DC 380 V

UCSD

DC 380 V

Stanford

Univ.

DC 380 V

North America Cn

Telecom

DC 380 V

NTT Group

NTT R&D

Atsugi and

Musashino

locations

NTT Facilities

Observation

system

NTT

communications

Large-scale DC

380 V system


HVDC standardization progress

AC power DC power

AC main

AC/DCConverter

ICT equipment

Interface XBatterysystem

Power feeding system

Rectifier

Definitions such as DC voltage range is defined at this interface point

Step 2: Power system architecture

⇒Complete, ITU-T 2014 published (L.1201)

Step 1: Interface specifications at input of ICT equipment

⇒Complete, ITU-T 2012 published (L.1200)

NTT Group worked on international standardization

500

400

300

200

100

0 50 u 10 m 60

Time [s]

Vo

ltag

e [

V]

Recover voltage

to 260 V until 10

ms

Recover voltage to

400 V until 50 us

Capable

voltage range

• Voltage range 260-400 V

•Voltage variation

(dip, interruption etc)

• Serge test, inrush current

ITU-T: International Telecommunication Union

Telecommunication Standardization Sector

L.1200 L.1201


Lineup of ICT equipment for HVDC

HVDC-supported products have been released (e.g. NEC, IBM and Hewlett-

Packard)

HVDC-supported products are expected to become more widespread

IBM:

zEnterprise 196

IBM:

zEnterpirse 114

HP: DL380

NEC: Express5800/

SIGMABLADE-M

1U

2U

3U

Blade

Main

Frame

HP ProLiant SL6500 scalable system

4U

Atworks: Stingray ZE UNICOM: D-1000

UNICOM: D-2000

Plathome:

TrusSPS series

（2U, 3U, 4U）

（storage ）

NEC: iStorage

Ｍ series

M300/M100/

M10e

（storage）

HP: C7000 Cisco:

UCS 5108


Dilemma of promoting new system

Situation of ICT

equipment venders

Situation of carrier and

operator

If carrier and operator say

that they will buy many types

of ICT equipment, we can

sell ICT equipment for HVDC.

If ICT vender will sell many

types of ICT equipment for

HVDC, we can introduce

HVDC system.

NTT will break this cycle and introduce HVDC

system.


NTT Group Strategy for Deploying HVDC system

NTT has focused on promoting HVDC system implementation.

NTT will introduce HVDC system to many NTT Group companies and promote it

in earnest from 2016.

http://www.ntt.co.jp/news2014/1408e/140804a.html

NTT HVDC World’s first search


Unify

pow

er

supply

infr

astr

uctu

re t

o H

VD

C

Achieve both energy

and energy cost reduction

Safe management

1st step HVDC accelerated

by introduction of new system

～2030 ～2030

Additional cost reduction

･Commodities cost

・Construction

・Maintenances

Reduce construction

cost by diverting

migration equipment

Power supply systems costs decrease

～2030 2016 2018 2020 2015 2014 ■Tokyo Olympics &

Paralympics

■Press release,

Technical Requirement

Guideline regarding establishing HVDC

■Increase HVDC-supported

ICT equipment

(2) installation of

HVDC-supported

ICT equipment

Make inexpensive by accelerating deployment

of HVDC-supported ICT equipment

2nd step Expansion by introduction of HVDC-supported ICT

equipment* in Telecom bldgs.

Final step Unified HVDC in Telecom bldgs.

2015

Target:100 bldgs+α

2020

Goal:1,000 bldgs (1 ) Replacement of

48-V rectifiers

based on age of

equipment

100％

100％

Now

Increase lineup of products

Accele

rati

on

of

HV

DC

in

sta

llati

on

Regarding power supply systems

About Network systems

Development of ICT equipment

conversion to HVDC-supported type

Constructio

n with

HVDC +

migration

equipment**

NTT Group accelerates installation of HVDC systems for telecom buildings

Reduction in energy consumption and energy cost is achieved through our strategy

Acceleration of adoption of HVDC-supported ICT

equipment

Roadmap

* ICT equipment, which receives HVDC directly, does not require migration equipment

** voltage conversion

equipment : from HVDC to

DC-48V or AC power line

(1)+(2)

Nu

mb

er

of

dep

loym

en

ts


Specifications of Technical Requirement (TR)

We published technical requirement for HVDC power supply interfaces of ICT

equipment

Items Specifications

Rated voltage 380 V *1

Operating

voltage range

From 260 to 400 V *2

Maximum rated

capacity

7.8 kW *1

Inrush current Limit of current level an

d time

*2

Abnormal

conditions

Voltage variation, voltag

e dips, short interruption

s, voltage surges/transi

ents

*2

Safety Protection against electr

ic shocks

*1

*1: NTT added in the TR.

*2: L.1200

410 V

400 V

260 V

0 V

2 kV

500 V

260 V

420 V

410 V 400V

0 V

Criteria a

Criteria b

Operating

voltage

Abnormal

voltage

Abnormal voltage

Over

abnormal

voltage

DC

AC

BATT

DC 380 V

Rack

～ PSU

Rectifier

Mother

board

ICT equipment

Interface of this TR

TR for ICT equipment based on ITU-T

L.1200.


Example of introduction of large-scale HVDC system

In NTT group, HVDC system has been installed not only at laboratory sites but

also associated companies.

Recently, large-scale HVDC system has been introduced in NTT Group.

Large-scale rectifier: 500-kW system (NTT Facilities)

Total power: 4 MW (500 kW x 8 systems)

Reduce power loss ⇒ Lower power consumption by 20%

Initial cost of this HVDC system was less than that of conventional system


Development of further savings

(Adaptive control)

NEDO: New Energy and Industrial Technology Development Organization

NTT group has been developing adaptive control technique for reducing

power consumption for data centers.

In adaptive control technology, we control number of working power modules

according to ICT load.

NTT Facilities activity in NEDO green IT project

Active

Active

Idle

Idle

Power module

Battery

Active

Active

Standby

Standby

Power module

Control of power module Battery

Active

Active

Heavy

load

Light

load

86

88

90

92

94

96

0 20 40 60 80 100

▲

▲

▲

▲ ▲ ▲ ▲ ▲

Load ratio [%]

Eff

icie

ncy [%

]

Increasing efficiency

using HVDC

With adoptive control

Without adoptive control

Increasing efficiency

using adoptive control

ＡＣ system

ICT eq.

ICT eq.

Light load Heavy load

Adaptive Power Supply Management

Operation

Operating

information

Idle

Halt

Deactivate

Determine control


Ease of controlling DC power supply unit It is easy to control power supply unit of DC system.

⇒We do not have to control synchronous and bypass circuits like AC in

system

Only connect

AC DC DC

Battery

AC DC

AC DC

PDU

PSU

ICT

2 1

Directly use battery power

PSU

ICT

AC DC

Need power conversion

Battery

Must be synchronous

AC system

DC system

PDU

3 4

UPS

CPU

CPU

AC AC DC

Battery

AC AC DC

1 2

Fewer power conversions

PDF RF LiB PDF ICT eq.


Application of HVDC (NTT Facilities)

Energy interchanging between regions

(Yamagata site)

DC-G

AC-G

DC-G

DC power system for office buildings

(Obihiro system)

NTT group has been developing system using HVDC and renewable energy.

Verification tests at two sites for independent distributed-energy society.

These projects were supported by Ministry of Environment, Japan from 2012 to 2015


Obihiro Project

HVDC system was introduced in office-type building at Obihiro site.

DC-EMS control power modules such as rectifier, battery, and PSU of application side.

Left: Li-ion charger

Right: DC power convertor

(Rectifier & DC-PCS)

Flame-retardant Li-ion

Battery

(23 kWh)

Refrigerator TV & Blu-ray player

DC-EMS monitoring image System Configuration


Yamagata Project

HVDC system and renewable energies are introduced at Yamagata site.

HVDC DC bus is connected between building and houses.

DC power is supplied from building to houses.


Outline


1. Introduction

2. Advantage of HVDC

3. NTT group’s strategy and technical requirement

4. Application of HVDC

Next generation power supply system

1. System topology

2. Study of voltage levels

Summary


Outline of power supply system in data centers

6600 V 200 V

Generator

Battery

UPS Mother board PSU

PSU

POL

DC

DCDC

DC

1V

3.3V

DC

DCAC

DC

UPS

Battery

DC

AC

AC

DC

6600 V 200 V

Generator

Efficiency in conventional verification range: 95~98%

Efficiency of power translation to CPU: about 78%

PDU

UPS Generator

ICT equipment Data center Electric power system outline

Mother board PSU

Mother board PSU

There is much power loss when we consider entire power supply system from

input port of building to input port of CPU. To reduce power conversion loss,

we have to particularly consider power topology of ICT rack.

Mother board

Infrastructures side ICT equipment side

Power supply is

defined from

Infrastructures

only

Power rating

Battery

Increase power

supply rate

CPU

Utility grid

PDU

Utility grid

Memory

Chip, etc

Air conditioner Air conditioner

ICT

equipment

Power supply is

defined from

Utility grid to CPU

Review of ICT rack is necessary

Circuit model

Power supply

15% Power supply

50% DC

DC


Considering trend that power consumption of CPU is increasing and

line distance between grid and CPU, optimized voltage cascade is DC

380 and 48 V.

What is optimized voltage cascade from input port of

building to input port of CPU?

AC 6600 V

CPU

AC

DCCPU

AC 6600 V AC

200 V

DC

380 V DC

48 V DC

1 V, etc

DC 1 V

DC

DC

PSU

POL

DC

DCDC

DC

1V

3.3V Memory

DC

DCAC

DC

UPS

Battery

DC

AC

AC

DC

6600 V 200 V

Engine Motherboard

CPU

12 V

Conventional

system

Point 2 Point 1

380V,etc

380 V

DC

DC

Engine

DC

DC

Optimized voltage cascade in telecom buildings

and data centers


Power block system of power supply

When we use AC/DC and DC/DC converters as power blocks, we can

move power blocks according to building conditions.

AC 200~480 V AC

DC

DC 48 V DC 380 V

Motherboard DC

DC

BAT BAT

ICT equipment side Infrastructure side

Grid

AC 200~

480 V DC 380 V DC 48 V

AC

DC

DC

DC

DC

DC

48-V input motherboard

DC 1

or

3.3 V

Point 1


Configuration of power block system Point 1

Power block system can be used to construct various reliable and capacity power supply

systems by adjusting number of batteries and number of converters.

Using this topology, we can construct flexible system.

MB

MB

DCDC

AC

DC

BAT

DCDC

AC

DC

380 V 48 V

BAT

MB 48 V

DCDC

DCDC

DCDC

48 V

48 V

AC 200~480 V

BAT MB DC

DC

AC

DC

DCDC

DCDC

AC

DC

BAT

RF

MB

N parallel connection

DCDC

AC

DC

DCDC

AC

DC

DCDC

AC

DC

48 V

BAT BAT

RF ICT equipment side

AC

DC

AC

DC

AC

DC

N parallel connections

7 serial connections

Infrastructure ICT equipment Power

feeding

system

Applicable

building

Backup

time

Renew

al time

DC 48 V

system

Small-scale

telecommunic

ation buildings

(under 100

kW)

telecommuni

cation

buildings:

About 3 h

Over 5

years

HVDC

system

From mid- to

large-scale

telecommunic

ation buildings

and data

centers

(100 KW and

over)

telecommuni

cation

buildings:

About 3 h

Datacenters:

About 10

min

Over 5

years

AC direct

shipment

system

Data centers

that do not

require

reliability

Several

minutes

About

3 years

DC

DC

DC

DC

DC

DC

DC

DC

DC

DCDC

DC

DC

DC

DC

DCDC

DC


Issues of 12 V on mother board Point 2

DC

DCCPU

memory

HDD 12V

DC

DC

Capacitor

3.3V

1V

Current slew rate of CPU is

increasing with decreasing

Input voltage.

Driving voltage: 5 V ⇒ １V

Current range: 20 A ⇒ 100A

(CPU power consumption is 100 W)

[year] Po

we

r co

nsu

mp

tio

n

of C

PU

[W

]

0

100

200

300

400

2000 2006 2012

Intel AMD

(studied data by qunie Corporation in 2013)

Increasing

Power consumption is increasing

Power consumption and current slew rate of CPU are increasing

Size of line and converters inside motherboard using DC 12 V of input

voltage is increasing.

Thick cable

and pattern

Large

capacitor


Advantages of 48 V compared to 12 V Point 2

Reducing Cross-sectional area of cable

Space saving

Equality of efficiency for converter

Equality of safety


Advantage of 48 V compared to 12 V (①) Point 2

0

100

200

300

400

500

0

500

1000

1500

2000

0 10 20 30 40 50 60

When we use 48 V, we can reduce cable diameter and power component

space (POL and capacitor)

Relationship between cable cross-

sectional area and input voltage

Condition: 30 m (guideline for electric power system)

48-V system can reduce cable

diameter.

⇒48 V is excellent with system

2000

1500

1000

500

0

325 mm2

14 cables

200 mm2

2 cables

0 10 20 30 40 50 60

325 mm2

4 cables

38 mm2

2 cables

400

300

200

100

0

500

Input voltage [V]

Cro

ss-s

ection a

rea [

mm

2]

Copper

weig

ht

[kg]

1.8 kW

6.7 kW

12 V 48 V

DC

DCCPU

memory

HDD 12 V

DC

DC

Capacitor

3.3 V

1 V

DC

DCCPU

memory

SSD

48 V DC

DC

Capacitor

3.3 V

1 V Capacitor

energy

U=1/2・C・V2

Capacitance

of capacitor

can be

reduced to

about 1/502＝

1/2500


Advantage of 48 V compared to 12 V (②) Point 2

Recently, efficiency of 48-V input converter has not been lower than 12-V

input converter.

Safety measure is same level as 12 V because 48 V is SELV (up to 60 V).

50

60

70

80

90

100

0 10 20 30 40 50 60

Eff

icie

ncy

[%

]

Input voltage [V]

isolated

non-isolated

Efficiency of 48-V converter is high

⇒ No longer disadvantage

Relationship between converter efficiency and

input voltage (marketing research)

12 V 48 V

Safety measure is same level as 12 V

because 48 V is SELV (up to 60 V)*.

*IEC60950

SELV: safety extra low voltage

SELV CIRCUITS shall exhibit voltages that are safe to

touch both under normal operating conditions and after

a single fault.

Voltages under normal conditions:

Under 42.4V peak or 60 V DC

IEC 60950

Information technology equipment – Safety –

Part 1: General requirements


48-V trend in other industries Point 2

◆In 2011, German auto makers (Volkswagen, Audi, Porsche, Daimler, BMW) announced

that they will use 48-V power supply units in vehicles.

◆Audi disclosed concept car “iHEV” in 2012, which uses 48-V technology.

◆Standardization of 48 V is proceeding. LV148, which concisely describes 48-V system,

has already been published by VDA.

http://techon.nikkeibp.co.jp/article/HONSHI/20131122/318108/?rt=nocnt


Application area of 48-V system Point 2

Relationship between cable distance and maximum allowed power

19-inch rack:

3 m x 20 kW

= 60 kWm

60 kWm, unit multiplied by power consumption and distance, is application

area of 48-V system. Thus, 48-V system can be applied in not only ICT

industry but also in wide range of industries, such as automotive, and home.

Air plane (control unit):

30 m x 2 kW

= 60 kWm

Home cabling:

20 m x 3 kW

= 60 kWm

Car cabling:

6 m x 10 kW

= 60 kWm


Aggregate of DC voltage (48 and 380 V)

200 V

12 V

～

Mild HV

EV , HV

(power unit)

Control unit

12 V

ICT equipment

Server

HVDC power feeding

Truck

General cars

5 th grade

power unit

AC power feeding (AC)

DC

vo

lta

ge

[V

]

48 V

380 V

Voltages will be aggregated to DC 48 and 380 V in future.

Particularly, ICT industry and automotive industry markets are very large and

are expected to grow significantly. Significant cost reduction in equipment

and parts to use common voltage is expected.

DC 380 V

Infrastructure side or large motor

DC 48 V

Rack side or user side

12 V 12 V 12 V

24 V 24 V 24 V 28 V

48 V 48 V 48 V 48 V 48 V 48 V

200 V 200 V 260 V

380 V 380 V 270 V

power unit (AC)

(power unit)

ICT EV bike

Fork lift

Airline Automotive Space

Industry

Home

Industry Industry Industry

Infrastructure of telecommunication buildings and

data centers

Automotive motors

main home infrastructure (PV, fuel cell, refrigerator, air

conditioning)

Aircraft power systems

On-site power (Smart Community)

380 V


Summary

We designed HVDC system topology and developed

many power components and introduced many HVDC

systems.

Moreover, we have worked on international

standardization ( ITU-T L.1200 and ITU-T L.1201. )

We have established HVDC strategies for introducing

HVDC systems in telecom buildings and data centers of

NTT Group. Against this background, we have

described technical requirement.

We also described new power supply system concept

to further reduce power consumption and cost.

We will promote DC systems worldwide.


【Reference】 Limit of 12-V system in rack

Recently, each component, such as CPU, memory and storage, is put in each

chassis, and power supply is centralized in rack.

Therefore, current is increasing and bus bar become thick using 12-V bus.

■ Power supply topology in rack

PS

U

Storage, Memory, CPU

PS

U

PS

U

PS

U

DC

AC

DC 12 V




board

(a) Conventional configuration

Power chassis

CPU chassis

Memory chassis

Storage chassis DC

AC

DC 12 V chassis

(b) Recent configuration

CPU Storage Memory PSU

ICT

equipment

Power chassis

CPU chassis

Memory chassis

Storage chassis DC

AC

DC 48 V chassis

(c) Future configuration

current increase

⇒thick bus bar

Centralization

of power

supply

Current decrease

⇒thin bus bar

hvdc power supply system implementation in ntt group … · c reduce construction achieve both...

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