Power Dissipation Optimization Process in Aircraft Secondary Power Distribution Systems

Neno Novakovic

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November 1, 2014 ◊ Future of Flight Aviation Center ◊ Paine Field Everett, Washington

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• Introduction, Aircraft Electrical Power History and Concepts

• Power Distribution Units, Configurations and Characteristics

• Problems, Challenges and Constrains

• Solution, Tools and Methods

PROPOSED AGENDA

• During the WWI era, radio communication was introduced and 12 volt lead acid battery and air or engine driven DC generators were used.

• 28 V dc aircraft system voltage was established during WW II era (then sometimes called a 24 volt , or 27 volt or 30 volt system).

• In the early 1940s the decision was made to adopt 400 Hz, 3-phase, 115/200 volt system as future aircraft electrical power system.

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AIRCRAFT ELECTRICAL POWER SYSTEM HISTORY

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0

200

400

600

800

1000

1200

1400

1600

1960 1970 1980 1990 2000 2010 2020

PO

WE

R R

AT

ING

[K

VA

]

AIRCRAFT AC POWER GENERATION

AIRCRAFT ELECTRICAL POWER GENERATION HISTORY

DC-9

B757

B747 A340

A380

B787

ELECTRIC POWER DISTRIBUTION CONCEPTS

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EPDS EPDS

PDU-1

PDU-2

PDU-3

PDU-N

CENTRALIZED DECENTRALIZED

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SECONDARY POWER DISTRIBUTION WITH COCKPIT CIRCUIT BREAKERS CONCEPT

AC

115 V AC BUS

28 V DC BUS

TRU

AC ELECTRICAL LOADS

DC ELECTRICAL LOADS

COCKPIT CIRCIUT BREAKER PANEL

THERMAL CIRCUIT BREAKER

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SECONDARY POWER DISTRIBUTION CONCEPT WITH INTEGRATED PDUs

AVIONICS AND

INTERFACE CONTROL

PDU PDU PDU

PDU PDU PDU

28 V DC

28 V DC

115 V AC

115 V AC

COCKPIT MULTY FUNCTIONAL DISPLAYS

PDU HARDWARE CONFIGURATION

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• Each PDU contains up to n AC and/or DC power modules with Solid State Power Controllers (SSPCs) designed to switch power ON and OFF to aircraft electrical loads in response to commands from dedicated system controllers.

DC POWER MODULE ARCHITECTURE

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SSPC 1

SSPC 2

SSPC 3

SSPC K

INPUTFILTER

INTERFACE

BOARDCONTROLLER

POWER FEED

DATA AND CONFIGURATIONCONTROL BUS

LOAD #1

LOAD #2

LOAD #3

LOAD #K

POWER RETURN

POWER MODULE

+28 V DC

AC POWER MODULE ARCHITECTURE

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SSPC 1

SSPC 2

SSPC 3

SSPC L

INPUTFILTER

INTERFACE

BOARDCONTROLLER

POWER FEED

DATA AND CONFIGURATIONCONTROL BUS

LOAD #1

LOAD #2

LOAD #3

LOAD #L

POWER RETURN

POWER MODULE

115 V AC PHASE A

INPUTFILTER

INPUTFILTER

115 V AC PHASE B

115 V AC PHASE C

POWER FEED

POWER FEED

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CHALLENGES AND CONSTRAINS

• Total system equipment weight.

• Architecture driven by minimal distance between power source and electrical load.

• Bus power and load segregation.

• Load shed pattern.

• System hardware limitations.

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PHISICS OF HARDWARE AND SYSTEM LIMITATIONS

1. Limit on AC and DC input feed current.

2. Limit on power dissipation on SSPC components .

3. Limit on internal control power dissipation.

1

3

2

POWER DISSIPATION DEFINITION

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• For each Power Module at position X, total power dissipation can be defined as a sum of all individual SSPC channel power dissipations:

were

I is a continuous load current through SSPC channel, which depends on aircraft configuration ε,

and Ron is SSPC channel ON resistance, as a function of ambient operating temperature Temp,

PD_MX = RON [W]

I=I(ε) [A]

Ron=Ron(Temp) [Ω]

AIRCRAFT DESIGNATED FLIGHT PHASES

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• Load currents of the electrical and electronic equipment are dependant on aircraft configuration.

• For the purpose of this analysis, the aircraft configuration parameter ε, can be tied to a different aircraft designated flight phases, listed in the following order:

- Ground Loading

- Engine Start

- Taxi

- Takeoff

- Climb ε - Cruise

- Descent

- Landing

SSPC CHANNELS CONFIGURATION

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• SSPC channel ON resistance Ron includes MOSFET ON drain-source resistance, current sensing resistance, and some other elements relevant to specific hardware configuration.

PDU TOTAL POWER CONSUMPTION

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• PDU total power consumption can be calculated as a sum of Power Supply power consumption, and all n Power Modules power dissipations:

were

Power Supply power consumption includes:

- Processor power

- Power Supply efficiency, and

- Control Switching power losses.

PDU_TPC = PS_Power_Concumption + [W]

POWER ANALYSIS NUMERIC ALGORITHM

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DC AC

MODULE 1

MODULE 2

CONFIG

M1 1,

M2 1,

Mn 1,

M1 2,

M2 2,

Mn 2,

:=

MODULE n

SSPC1 SSPC2 SSPCK

MODULE 1

MODULE 2

TDCM ε( )

TDCM_1ε 1,

TDCM_2ε 1,

TDCM_nε 1,

TDCM_1ε 2,

TDCM_2ε 2,

TDCM_nε 2,

TDCM_1ε k,

TDCM_2ε k,

TDCM_nε k,

:=

MODULE n

n

K

ε

PDU CONFIGURATION LOAD DATABASE

THREE DIMENSIONAL CURRENT MATRIX

POWER ANALYSIS BLOCK DIAGRAM

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PDU POWER ANALYSIS RESULTS

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40− 30− 20− 10− 0 10 20 30 40 50 60 70 8050

70

90

110

130

150

Ambeint Temperature [C]

Tota

l Pow

er C

onsu

mpt

ion

[W]

PDU_TPC Temp ε, ( )

Temp

40− 30− 20− 10− 0 10 20 30 40 50 60 70 800

2

4

6

8

10

12

14

16

18

20

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Ambeint Temperature [C]

Pow

er D

issi

patio

n [W

] PD_M1 Temp ε, ( )

PD_M2 Temp ε, ( )

PD_M3 Temp ε, ( )

PD_M5 Temp ε, ( )

Dissipation_Limit

Temp

Phase_Of_Flight ε( ) "CLIMB"= Phase_Of_Flight ε( ) "CLIMB"=

POWER DISTRIBUTION OPTIMIZATION PROCESS

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REFERENCES

• “Overcoming Power Challenges With Power Distribution Units”, Dave Proli, Power Electronics Technology, May 31 2012, www.powerelectronics.com.

• “MOSFET Power Losses Calculation Using the Data-Sheet Parameters” by Dr. Dusan Graovac, Marco Pϋrschel, Andreas Kiep, Application Note, V 1.1 July 2006, INFINEON.

• “Electrical Power Distribution Architecture for All Electric Aircraft” D. Izquierdo, R. Azcona, F. J López del Cerro, C. Fernández, J. Insenser, 27th International Congress of the Aeronautical Science ICAS 2010.

• 787 Program, Electrical System and Batteries, Sinnet-TOS-Deck.pdf

• “Power Dissipation Optimization Process in Aircraft Secondary Power Distribution Systems”, N. Novakovic, M. Manojlovic, SAE Aerospace 2013-01-2275.

AIRCRAFT ELECTRIC POWER DISTRIBUTION

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