Aircraft Electric Power SystemA Power Conversion Perspective

Waleed Said

September 29th 2011

Based on an article published in the August 2011 issue of the IEEE Power and Energy Magazine by the speaker. Photographs of hardware are provided by and are used with permission from Hamilton Sundstrand

Export permitted under EAR 9E991 (Re-export is not authorized without first obtaining required authorization from Hamilton Sundstrand. Diversion contrary to U.S. law is prohibited. NLR No License Required

Outline Two Thrusts

Overview of Aircraft Electric Systems Power Sources Types

Conversion in Power Sources

Subsystems

Build Notional Electrical System

Identify Power Conversions within the System Identify Power Conversions within the System

Power Electronics in Aerospace Power Electronics Progression on Aircraft

What Introduced Power Electronics to Aerospace

Power Electronics Current State

Challenges of Power Electronics in Aerospace

Future Trends

Primary Power Sources

Engine Driven Supplies

Integrated Drive Generator (IDG) Three Phase 400Hz 115V L-N

Hydro-mechanical Conversion (@ the Source)

Constant Speed Drive (CSD)

Variable Speed Constant Frequency (VSCF)

CSDVariable Speed

Engine Shaft

ConstantSpeed

3115V400 Hz

IDG

VariableFrequency Variable Speed Constant Frequency (VSCF)

Three Phase 400Hz 115V L-N

Electrical Conversion @ Generator Output (@Source)

Power Electronics Converter

Variable Frequency Generator Three Phase 360-800 Hz 115V or 230 V L-N

Electrical Conversion @ Load (@ Point of Use)

Power Converter3115V400 Hz

Variable SpeedEngine Shaft

Frequency

3115V400 - 800Hz

Variable SpeedEngine Shaft

Primary Power Sources (Continued) Auxiliary Power Unit (APU) Driven

No Thrust Gas Turbine Engine

Constant Speed Generator

Three Phase 400Hz 115V L-N

No Electrical Conversion Needed

Emergency Power Source

Ram Air Turbine (RAT) Driven

Constant Speed Generator

Three Phase 400 Hz 115 L-N

No Electrical Conversion Needed

Primary Power System

Gen + GCU

APU

~

RAT

Gen + GCU

Gen + GCU

Gen + GCU

AGen + AGCU

Gen + RAT GCU

Engine Engine

ExternalPower Primary Power Bus & BPCU Emergency Bus

Secondary Power System

ATU TRU TRUEP

Secondary AC Bus 28V DC Bus

AC & DC SSPCsAC & DC SSPCs DC SSPCsAC SSPCs

HVDC System

ATRU ATRU

HVDC Bus

Motor Controllers

HVDC Bus

Motor Controllers

The Electrical System

Engine APU

External

RAT

Primary Power Bus & BPCU Emergency Bus

Gen + GCU

AGen + AGCU ~

Gen + RAT GCU

Engine

Gen + GCU

Gen + GCU

Gen + GCU

ExternalPower

HVDC Bus

ATRU ATU

Secondary AC Bus 28V DC Bus

Primary Power Bus & BPCU Emergency Bus

TRU TRUEP

AC & DC SSPCsAC & DC SSPCs DC SSPCsAC SSPCs

AC & DC Loads DC LoadsAC LoadsPrimary AC

LoadsMotor Loads

Motor Controllers

AC Feeders

Generators

Power Panels115 VAC / 28VDC

External Power

Generation & Distribution Architectures

ASGs

Power panels & HVDCExternal Power -

SSPC Centers

SSPC Loads

Electromagnetic ConversionPreserving Power Quality Thru Multi 6 Pulse Transformers

ExternalPower

ATRU ATU

Primary Power Bus & BPCU Emergency Bus

TRU TRU

Gen + GCU

AGen + AGCU ~

Gen + RAT GCU

Gen + GCU

Gen + GCU

Gen + GCU

EM

HVDC Bus

ATRU ATU

Secondary AC Bus

TRU TRUEP

AC & DC SSPCsAC & DC SSPCs DC SSPCsAC SSPCs

AC & DC Loads DC LoadsAC LoadsPrimary AC

LoadsMotor Loads

Motor Controllers

EMConversion

Layer

28V DC Bus

Reduces Harmonic Distortion in Line Current Due to Rectification

Multi-Six-Pulse Transformer-Rectifiers

12 Pulse Isolation

Mainly TRUs

Minimize 5th & 7th Harmonics

Utilized for the Secondary Power Distribution System

Electromagnetic Conversion

3 DC

18 Pulse Auto

Minimize 5th, 7th, 11th & 13th Harmonics

Utilized for the HVDC and in some Motor Controllers

3 DC

Power Electronics ConversionBetween Sources and the Loads

ExternalPower

ATRU ATU

Primary Power Bus & BPCU Emergency Bus

TRU TRU

Gen + GCU

AGen + AGCU ~

Gen + RAT GCU

Gen + GCU

Gen + GCU

Gen + GCU

HVDC Bus

ATRU ATU

Secondary AC Bus

TRU TRUEP

AC & DC SSPCsAC & DC SSPCs DC SSPCsAC SSPCs

AC & DC Loads DC LoadsAC LoadsPrimary AC

LoadsMotor Loads

Motor ControllersPowerElectronics

28V DC Bus

Power Conversion Motor Controllers

HVDC to Variable Voltage and Frequency Converters

Some AC to AC Converters Active Rectifiers

ATRU Based

The Power Electronics Layer

Solid State Switching SSPCs

MOSFETs

On/Off Operation

Programmable Trip Curves

Diagnostics & Health Monitoring

Power Electronics in Aerospace

Historic Perspective

The Early Days

No Power Electronics on Airplanes

Breakers & Contactors AC/DC Converters

Early Power Electronics Devices

Large & Heavy

Some Will Turn On but Cant be Turned Off !?! SCR

Bi-Polar Transistors Difficult to Use

Low Reliability

Wide Variability Range

Manual Assembly Performance Not Consistance

Expensive Characterization & Grouping

Limited Use in Aerospace to TRU Products

Unregulated Transformer + AC/DC Converter

115 Vac 28 Vdc

The IGBT is Born

Enabled High Power Electronics TechnologyAdvance Aerospace Industry

Aircraft Went VF!

Variable frequency systems Variable frequency systems Generator directly mounted to engine shaft variable speed

Variable frequency distribution to loads

Main enabler for motor drives in aerospace Advent of More Electric Airplane

The Dreamliner

Effects & Challenges

Electrification of Loads Impacts System Certification

Electrifying Flight Critical Loads Imposes Flight Critical Requirements on Electric System & Power Electronics Equipment

Higher Reliability Requirements Under Higher Threat Levels

Significant Cost & Schedule Impact Due to Elevated Type Certification

EMI and Power Quality EMI and Power Quality

Motor Controllers Distort Power Quality and Generate EMI Noise!

Mitigating One Normally Exacerbate the Other

Heavy and Expensive Filter Solutions

Components Availability

Aerospace Low Volume

Harsh Environment Drives Cost

Exotic Components, Alloys and Compounds

Suppliers Need to Listen to Aerospace

Active Rectification Emphasis on Power Quality & EMI

Smaller Lighter & More Efficient that TRUs

Future Trends Power Quality

Boeing Harmonic Limits

0.4

0.45

0.5

Boeing Limits

Simulation

THD = 1.179%

21

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62

Harmonic Order

C

u

r

r

e

n

t

H

a

r

m

o

n

i

c

s

(

A

r

m

s

)

Future Trends Advanced Topologies

+

Vdc

IPT

L1

C1

L2

Filter

Smaller, Lighter, More Efficient Inverters

Future Trends Components

High Temp Capacitors High Temp SiC FETsHigh Temp SiC FETs

Wide Bandgap Devices GaN

BN Powder particles (Polartherm) BN Powder particles coated with epoxy

Magnetics Thermal Management

The Journey has Just Started

Where We Were Yesterday Where We Are Today