UPS Topologies and Multi-Module Configurations

IEEE IAS SectionAtlanta GA

November 17, 2008

2 / Title or job number /

04/10/23

Agenda

UPS TopologiesLine Interactive UPSDelta Conversion UPSDouble Conversion UPSRotary UPS

UPS Design Market Drivers

UPS Components

Multi-Module UPS Configurations

3 / Title or job number /

04/10/23

Critical Power System

ATS

TVSS

Power Quality Distribution

PDU

Generation

Paralleling Switchgear

Critical Load

UPSServersStatic

Switch

4 / Title or job number /

04/10/23

Line Interactive UPS

5 / Title or job number /

04/10/23

UPS Topologies – Line Interactive

Line Interactive

Runs on AC power from Utility and switches to Inverter if Utility source power quality is not within predetermined tolerance. Provides some surge protection.

Benefits – very efficient due to minimizing inverter run time

Disadvantages – limited surge protection

Application – Single computer or single rack

6 / Title or job number /

04/10/23

Delta Conversion

7 / Title or job number /

04/10/23

This Line Interactive system carries the load by using both the utility line by means of a Line Conditioner (Course Regulation) and two converters (Actually two inverters for Fine Regulation & Battery Charger).

This topology can regulate the load voltage by manipulating the secondary winding of the series t-former using the Series Converter.

Advantages• System does not go on battery for voltage fluctuations.• System efficiency is higher in normal mode.

Disadvantages• The unit needs two inverters, less reliability.• It circulates more ripple current to the batteries.• If the utility frequency goes out of tolerance, the unit must go on batteries.

Delta Conversion

8 / Title or job number /

04/10/23

Double Conversion UPS

9 / Title or job number /

04/10/23

UPS Topologies – Double Conversion

Double ConversionRectifies AC power into DC and then converts the DC back to AC. Provides clean power, completely isolated from the Utility during normal operation.

Benefits – No interruption of Power; Protects load from Utility spikes and Surges

Disadvantages – Greater losses than Line Interactive design

10 / Title or job number /

04/10/23

Rotary UPS

11 / Title or job number /

04/10/23

UPS Design Key Market Drivers

Reliability – The 5 “9’s” - 99.999% up time

EfficiencyEPA InfluenceGreen Grid

Server TechnologyVoltageOutage Ride Through

12 / Title or job number /

04/10/23

Efficiency

Line Interactive UPS ~98% efficient

Double Conversion ~ 92% to 94% efficient

Methods to improve UPS efficiencyEliminate Input and Output Transformers“ECO” mode -Line interactive mode of operation

Data Center Efficiency TrendsEliminate PDU transformersElectrical Distribution Voltages

13 / Title or job number /

04/10/23

ECO Mode Overview

14 / Title or job number /

04/10/23

Server Technology

Server VoltagesToday –120VAC - 240VAC

600V or 480V distribution with PDU transformers400V distribution without PDU transformers

Future – 277 VAC? ; 480VAC?

Server Power Outage Ride ThroughCEMBA Curve – Now the “ITIC” CurveKey Factor for “ECO” mode.

15 / Title or job number /

04/10/23

CBEMA-ITIC Curve for Double Conversion UPS

16 / Title or job number /

04/10/23

UPS Components

RectifiersSCR or IGBTSCR – 6 Pulse and 12 Pulse

InvertersIGBT with PWM

Static Switch Module

TransformersInput TransformerOutput Transformer

FiltersInput Harmonic Filters

17 / Title or job number /

04/10/23

Rectifiers

•Rectifiers can be programmed to sequentially ramp up

IGBT Rectifier – Clean InputHigh power sinusoidal rectification – low harmonics, limited need for filters

SCR Rectifiers 6 Pulse – ~30% THD without filters – 7% with 5th Harmonic Filter<5% with 5th and 11th filter

12 Pulse – reduces harmonics by using parallel rectifiers with a phase shift ahead of one rectifier – requires input transformerLower efficiency than 6 Pulse

18 / Title or job number /

04/10/23

6 Pulse Current Input

THD without

filter

THD with

filter

19 / Title or job number /

04/10/23

12 Pulse Rectifiers

20 / Title or job number /

04/10/23

750 kVA - 6P vs 12P Rectifier – Energy Efficiency

Percentage load

6-Pulse - no Xfrmr

12-Pulse w/xfrmr

25% 92.8 % 91.8 %

50% 94.2 % 93.3 %

75% 94.2 % 93.2 %

100% 93.6 % 92.4 %

Efficiency

Difference

1.0 %

0.9 %

1.0 %

1.2 %

21 / Title or job number /

04/10/23

Inverters

Converts DC power into AC using IGBTs and PWM

Several different methods to implement PWM

22 / Title or job number /

04/10/23

Static Switch Modules

Static Switch Module consists of breaker or contactor in series with back to back SCRs.

Static Switch modules can be continuous duty or momentary rated. Momentary rated Modules have a breaker or contactor in parallel.

Continuous duty is required for ECO mode operation.

23 / Title or job number /

04/10/23

Input Isolation Transformer Input Isolation Transformer – required for 12 Pulse Rectifier

24 / Title or job number /

04/10/23

Output Transformer- Isolates load from inverter

- Provides greater protection to load during inverter failure

- Transformer MTBF > IGBT MTBF

UPS Output Transformer

25 / Title or job number /

04/10/23

Input Filters

5th Harmonic Cancellation

•The filter is designed to cancel the current distortion that is most present on the 5th harmonic.

Power Factor Correction•The input filter also raises the input pf to approximately 0.93 with addition of capacitors. This will allow the generator to operate more efficiently delivering more real power

26 / Title or job number /

04/10/23

Multi-Module UPS Configurations

Paralleling UPS ModulesCapacity or RedundancyCentralized BypassDistributed Bypass

Typical Parallel UPS ConfigurationsIsolated RedundantParallel RedundantDistributed RedundantSystem plus System

27 / Title or job number /

04/10/23

Parallel for Capacity

Multiple units = NNot recommended for a N System (single

system)Frequently used for System + System (N+N)

MTBF impactParallel for capacity reduces MTBF valueApproximately half the MTBF of a single unit

28 / Title or job number /

04/10/23

Centralized Bypass

29 / Title or job number /

04/10/23

Distributed Bypass

29

30 / Title or job number /

04/10/23

Centralized Bypass Cabinet

Distributed Bypass Configuration does not need this gear lineup

31 / Title or job number /

04/10/23

Parallel UPS Configurations

Isolated Redundant

Parallel Redundant

Distributed Redundant

System plus System

32 / Title or job number /

04/10/23

Isolated Redundant

33 / Title or job number /

04/10/23

Parallel Redundant

34 / Title or job number /

04/10/23

Distributed Redundant

35 / Title or job number /

04/10/23

System + System

36 / Title or job number /

04/10/23

Questions?

37 / Title or job number /

04/10/23

Contact Information:

Harry HandlinGE Power QualitySystems EngineerP 205-789-7479E harry.handlin@ge.com