Aviation Systems Design
Frederic ABADIE
[email protected]
General Principles Basic functions, Electrical Sources Electrical Power Line architecture
Electrical Generation Engine driven generators
Ram Air Turbine External Ground Cart
Electrical Distribution Power Distribution Centre Components : ▪ Circuit Breakers : C/B, RCCB, SSPC ▪ Transformers
More Electric Aircraft 2012-2013
Aviation Systems Design
2
General Principles Basic functions, Electrical Sources Electrical Power Line architecture
Electrical Generation Engine driven generators
Ram Air Turbine External Ground Cart
Electrical Distribution Power Distribution Centre Components : ▪ Circuit Breakers : C/B, RCCB, SSPC ▪ Transformers
More Electric Aircraft 2012-2013
Aviation Systems Design
3
Basic functions of Electrical System : Generate electrical power required by Aircraft electrical loads, insuring
power quality in all aircraft configurations Distribute electrical power to the consumers Provide information to the crew (status & alerts, maintenance info...)
Aircraft electrical sources
AC : Alternative Current DC : Direct Current
Flight / Ground Engine electrical generator Flight / Ground Flight
Auxiliary Power Unit electrical generator
Alternative (AC)
Ram Air Turbine
Alternative (AC)
Flight / Ground Batteries Ground 2012-2013
Alternative (AC)
External Ground Cart Aviation Systems Design
Continuous (DC) Alternative (AC) 4
Architecture : Electrical Power Line
DC busbar 28 VDC
AC Generator
DC Power Contactor
AC Power Contactor
AC Circuit Breaker
Transformer Rectifier Unit
AC busbar 115 or 230 VAC 400 Hz or VF
AC Network can be: 115VAC or 230 VAC Fixed Frequency (400 Hz ) or Variable Freq 2012-2013
Aviation Systems Design
5
2012-2013
Aviation Systems Design
6
Segregated Power lines Normal Circuit - Feeding all consumers - Powered from : Engines APU
Essential Circuit - Feeding essential A/C functions Flight Controls Main pumps : Fuel, Hydraulics Cabin pressurisation...
- Powered from : Engines APU RAT Batteries 2012-2013
Aviation Systems Design
7
General Principles Basic functions, Electrical Sources Electrical Power Line architecture
Electrical Generation Engine driven generators
Ram Air Turbine External Ground Cart
Electrical Distribution Power Distribution Centre Components : ▪ Circuit Breakers : C/B, RCCB, SSPC ▪ Transformers
More Electric Aircraft 2012-2013
Aviation Systems Design
8
1st Generation : Integrated Drive Generator (IDG) AC generator driven by the engine through the gearbox (variable speed ~ 4 500 / 9 000 rpm) Equipped with Constant Speed Drive (CSD) to regulate rotation speed to constant value Usual rating : 70 kVA to 150 kVA Characteristics : 115 VAC , 400Hz ; 3-phases
2012-2013
Aviation Systems Design
9
New generation : Variable Frequency Generator (VFG) AC generator driven by the engine through the gearbox (variable speed ~ 4 500 / 9 000 rpm) Frequency : 400Hz < f < 800 Hz Usual rating : 90 kVA to 250 kVA Characteristics : 115 VAC to 230 VAC ; 3-phases
2012-2013
Aviation Systems Design
10
Electrical Regulation Point Of Regulation (P.O.R.) : Quality of electrical generation must be measured at consumer busbar Power Contactor P.O.R. towards Generator Control Unit
Feeders
2012-2013
Aviation Systems Design
11
APU Generator AC generator driven by the APU (running at constant speed) Constant Frequency : 400Hz Usual rating : 90 kVA to 250 kVA 115 VAC to 230 VAC ; 3-phases
2012-2013
Aviation Systems Design
12
Ram Air Turbine Emergency power source, automatically deployed when all others Electrical Generators are lost
Operative above a given air speed (~100 knots) Provides Electric and/or Hydraulic power Typical rating : 50 to 150 kVA Constant Frequency (~ constant speed) 115 VAC to 230 VAC ; 3-phases 2012-2013
Aviation Systems Design
13
External Ground Cart (Ground Power Unit) AC generator : 115 VAC , 400Hz +/- 5Hz , 3-phases Typical power : 90 kVA per A/C plug
2012-2013
Aviation Systems Design
14
General Principles Basic functions, Electrical Sources Electrical Power Line architecture
Electrical Generation Engine driven generators
Ram Air Turbine External Ground Cart
Electrical Distribution Power Distribution Centre Components : ▪ Circuit Breakers : C/B, RCCB, SSPC ▪ Transformers
More Electric Aircraft 2012-2013
Aviation Systems Design
15
Power Distribution Centre Cabinet including : ▪ Energy distribution busbars : Low impedance copper or aluminium bars for consumers connection ▪ Power source switching devices (contactors, relays) ▪ Aircraft harness protections (Circuit Breakers)
Power Distribution Centre
AC busbar 115 or 230 VAC 400 Hz or VF
2012-2013
Aviation Systems Design
DC busbar 28 VDC
16
Circuit Breakers (C/B) Protective devices for electrical harnesses and equipments 3-phase C/B 50 A
Single phase C/B 3A
C/B characteristics : 3-phase (115/230VAC) or single phase (115VAC / 28VDC)
Max current rating Tripping time (~10’s ms) Monitored or not FCOM (Flight Crew Operating Manual) extract : “In flight, Airbus does not authorise a pilot to reengage a C/B which tripped by itself, unless the Captain, using his/her emergency authority, judges it necessary for safe continuation of the flight. In this emergency case, only one reengagement should be attempted. C/B panel 2012-2013
On the ground, the pilot may reengage the C/B provided the action is coordinated with the maintenance team and the cause of the C/B tripping is identified” Aviation Systems Design 17
Remote Controlled Circuit Breakers (RCCB) Same tripping principle as classic C/B (thermal) Remotely piloted in Open / Closed position
through low power relay
RCCB allow to : Monitor CBs in remote areas (out of the cockpit) Centrally drive CB position through dedicated HMI in the cockpit 2012-2013
Aviation Systems Design
18
Circuit Breakers Monitoring Manual C/B (if monitored) and Remote Controlled C/B position can be displayed to cockpit crew through Engine & Warning Display
2012-2013
Aviation Systems Design
19
Solid State Power Controllers (SSPC) SSPC modules are semiconductor-based devices (FETs), integrated in
Power Distribution Centre electronic cards. They are both : Protection devices for aircraft wiring against overload (=Circuit Breaker)
Power supply switches for technical operation and load management (=Relay)
Main advantages: ~3 times lighter than C/B technology at equivalent switching power Faster switching (~1 ms) Programmable trip threshold I(t) Enhanced monitoring (status, voltages, currents, temperatures)
No mechanical noise 2012-2013
Aviation Systems Design
20
Transformer / Rectifiers Units (TRUs) Transformers allow to convert Alternative electrical power (Alternative
Current) into Continuous electrical power (Direct Current = DC) TR efficiency typically between 80% and 90% Basic principle :
Specific TRUs can be “reversible” and usable as static inverters 2012-2013
Aviation Systems Design
21
General Principles Basic functions, Electrical Sources Electrical Power Line architecture
Electrical Generation Engine driven generators
Ram Air Turbine External Ground Cart
Electrical Distribution Power Distribution Centre Components : ▪ Circuit Breakers : C/B, RCCB, SSPC ▪ Transformers
More Electric Aircraft 2012-2013
Aviation Systems Design
22
Electrical vs Hydraulics ? Weight reduction Enhanced maintenance capability and lower maintenance cost Low emissions, low noise
A trend for the whole aviation industry... Fly-by-wire is a standard since 30 years, but progress keeps on : Affected Systems : brakes, engine starter, thrust reversers, movable actuators, pumps
AIRBUS A380 and A350 from 3H / 2E to 2H / 2E BOEING B787 3H / 2E but no Bleed
And others companies ... 2012-2013
Aviation Systems Design
23
New trends towards More Electric Aircraft : Italy, 2010
Fuel cells : ▪ Flight tested since end of the 1960’s (NASA) ▪ Power rating ~100’s kW per stack ▪ Pros :
Emission-free
▪ Cons :
H is highly flammable Production uneasy Storage uneasy
ENFICA FC Rapid 200 Airbus
BOEING 2008
Harvesting technology Usable for low power devices Not industrial-level yet
2012-2013
Aviation Systems Design
24
Questions ?
