1. UPS Topologies and Multi-Module Configurations
IEEE IAS Section
Atlanta GA
November 17, 2008

2. Agenda Line Interactive UPS UPS Topologies UPS Design Market Drivers
Delta Conversion UPS
Double Conversion UPS
Rotary UPS
UPS Design Market Drivers
UPS Components
Multi-Module UPS Configurations

3. Critical Power System Critical Load Generation Power Quality
Distribution
TVSS
UPS
PDU
Servers
Static Switch
ATS
Paralleling
Switchgear

4. Line Interactive UPS

5. UPS Topologies – 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. Delta Conversion

7. Delta Conversion
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.

8. Double Conversion UPS

9. UPS Topologies – Double Conversion
Rectifies 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. Rotary UPS

11. UPS Design Key Market Drivers
Reliability –
The 5 “9’s” % up time
Efficiency
EPA Influence
Green Grid
Server Technology
Voltage
Outage Ride Through

12. Efficiency Line Interactive UPS ~98% efficient
Double Conversion ~ 92% to 94% efficient
Methods to improve UPS efficiency
Eliminate Input and Output Transformers
“ECO” mode -Line interactive mode of operation
Data Center Efficiency Trends
Eliminate PDU transformers
Electrical Distribution Voltages

13. ECO Mode Overview

14. Server Technology Server Voltages Today –120VAC - 240VAC
600V or 480V distribution with PDU transformers
400V distribution without PDU transformers
Future – 277 VAC? ; 480VAC?
Server Power Outage Ride Through
CEMBA Curve – Now the “ITIC” Curve
Key Factor for “ECO” mode.

15. CBEMA-ITIC Curve for Double Conversion UPS

16. UPS Components Rectifiers SCR or IGBT Inverters IGBT with PWM
SCR – 6 Pulse and 12 Pulse
Inverters
IGBT with PWM
Static Switch Module
Transformers
Input Transformer
Output Transformer
Filters
Input Harmonic Filters

17. Rectifiers IGBT Rectifier – Clean Input SCR Rectifiers
High 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 transformer
Lower efficiency than 6 Pulse
Rectifiers can be programmed to sequentially ramp up

18. 6 Pulse Current Input
THD without filter
THD with filter

19. 12 Pulse Rectifiers

20. 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%
93.2 %
100%
93.6 %
92.4 %
Efficiency
Difference
1.0 %
0.9 %
1.2 %

21. Inverters Converts DC power into AC using IGBTs and PWM
Several different methods to implement PWM

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

24. UPS Output Transformer
Isolates load from inverter
Provides greater protection to load during inverter failure
Transformer MTBF > IGBT MTBF

25. Input Filters 5th Harmonic Cancellation Power Factor Correction
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. Multi-Module UPS Configurations
Paralleling UPS Modules
Capacity or Redundancy
Centralized Bypass
Distributed Bypass
Typical Parallel UPS Configurations
Isolated Redundant
Parallel Redundant
Distributed Redundant
System plus System

27. Parallel for Capacity Parallel for capacity reduces MTBF value
Multiple units = N
Not recommended for a N System (single system)
Frequently used for System + System (N+N)
MTBF impact
Parallel for capacity reduces MTBF value
Approximately half the MTBF of a single unit

28. Centralized Bypass

29. Distributed Bypass 29

30. Centralized Bypass Cabinet
Distributed Bypass Configuration does not need this gear lineup

31. Parallel UPS Configurations
Isolated Redundant
Parallel Redundant
Distributed Redundant
System plus System

32. Isolated Redundant

33. Parallel Redundant

34. Distributed Redundant

35. System + System

36. Questions?

37. Contact Information:
Harry Handlin
GE Power Quality
Systems Engineer P E