This presentation discusses the High Voltage Hybrid Electric Propulsion (HVHEP) Activity

Beach, Raymond

NASA Technical Reports Server

ARMD Transformative Aeronautics Concepts Program
Convergent Aeronautics Solutions Execution Project
High Voltage Hybrid Electric Propulsion (HVHEP) 
Activity 
Strathclyde
August 2017
Raymond Beach
NASA Glenn Research Center
https://ntrs.nasa.gov/search.jsp?R=20170009461 2019-08-29T23:30:43+00:00Z
Convergent Technology
SSF 20kHz Power System
Ion Engine PPU 
Fault Clearance
Wind Turbine
Doubly Fed Machine
787 Variable Frequency
Power System
High Voltage
Self Healing Insulation
LeRC Testbed
Cable
GEN
Motor
Motor
Turbine  Engine
Cross-strapped
Power
Cross-strapped
Power
Cross-strapped
Power
Fuel
AES
Modular Power Systems
High Voltage/Variable Frequency 
Propulsion System
Smart RPC
CAS HVHEP Progress
• HVHEP Activity in fourth quarter/year 2 of 2 1
2
year effort
• Successfully exited 6 of 10 gated/milestone events
Event-driven activity Event-driven activity
Initial operation of low power testbed Setting less protection system with zero 
energy fault clearance
Stable control of variable frequency power 
system with DFIM 
Manufacturing approach for MFIS 
Multi-Functional Insulation Material (MFIS) 
concept 
Monitoring concept for detection of insulation 
breakdown events
Minimum power electronic conversion for 
high efficiency and low weight
Validate scaling laws for variable frequency 
ac power system with DFIM
Self-healing insulation material 
characterization
Scaling laws applied to N+3 for use in 
system comparative analysis 
HVHEP Teaming and Partners
NASA Team Members
• ARC – Distributed propulsion impacts on 
vehicle flight control
• LaRC - Self healing insulation materials
• GRC
– Multi-layered functional insulation 
system
– DFIM control development and power 
testbeds
Partners
PCKrause and Associates – Models and 
simulation of DFIM and power testbeds
MIT – Dynamic control using DYMONDS 
software
UT-CEM - High speed brushless DFIM
AFRL/Wright Patterson - INVENT 
aircraft secondary power model library
Hybrid Electric Propulsion Architecture
High Frequency/High Voltage Cable and Wire
Convergent Technologies
• Multi-functional insulation system with 
self-healing materials
• Baseline prototype Space Station 
Freedom 20 kHz flat cable system
• Enable Hybrid Electric Propulsion system
• Development of new materials for AC and DC 
electrical systems for various industries: Space, 
Aeronautics, Terrestrial Vehicles, Electronics
• Development of Modeling Tools
• New Cable Architecture
• Partnership with Industry and Universities
Multilayered Functional Insulation System
Current Status and Key Findings:
• No testing standards for high frequency  HV power 
transmission cables
• Cable design requires a system engineering approach with
integrated multidisciplinary  Model:  EM fields, Mechanical, 
Temperature, Pressure
• High thermal conductive insulator not needed for rectangular 
cable configuration but useful for motor windings
• Achieved breakdown voltage of 43.7 kV in multilayered 
insulator prototype
• Need to design materials with increased performance life to 
reduce likelihood of disruptive discharge events
• Continue development of advanced lightweight conductors, 
and EM shielding materials to keep cable weight low
• Collaboration with industry (Gore, Mersen) to address 
manufacturing
Impact To NASA
Multi-Functional Insulation Material (MFIS) concept 
Future Work:
Self-Healing Insulation Materials
• Current Status
• Proposed Future Work
– Evaluate utility of current self-healing materials in 
motor winding prototypes subject to use 
environment conditions 
– Develop self-healing materials for insulation 
application with service temperatures in the 300°C 
range
– Synthesize various polymer compositions to assess 
thermal, mechanical and electrical self-healing 
under relevant use environments.
Inherently Self-Healing Material
High Dielectric Breakdown 
Strength
Low Permittivity/Dielectric Constant Low Dielectric 
Loss
Survey of self-healing materials to evaluate suitability for insulation application 
Affinity was coated 
onto copper, cut 
through to simulate 
chafing and cuts, then 
tested by running 26A 
of current.  Insulation 
was restored to 
prevent shorting.
Cut through insulation 26A current ran thru damaged 
insulated conductor 
Large cuts & gouges thru insulation
Damage enough to cause shorts
No visible cuts on insulation
Scratches are on copper
Cuts closed to prevent shorts
Self-healing insulation material characterization
Variable Frequency Power System
Convergent Technologies
• Boeing 787 variable frequency power 
system (400 to 800 Hz)
• Wind turbine generators with doubly 
fed electrical machines to enable 
variable speed operation
DFIM
DFIMDFIGPMDC Motor
BatteryDCAC
 Inverter Board
+48VDC Power 
Supply
ENC. 
Incremental 
Encoder
Torque 
Sensor
DFIM PMDC Generator
DC AC
Inverter Board
Torque 
Sensor
Torque 
Sensor
Torque 
Sensor
PMDC 
Generator
PMDC 
Generator
Total DFIG 
Output CTs
Bus 
PTs
Total DFIM #2 
Output CTs
Total DFIM #1 
Output CTs
Total DFIM #3 
Output CTs
Rotor Phase 
A,B Currents
+42Vdc Bus 
Voltage
Phase A,B 
Currents
L
Load 
Resistor
L
L
Load 
Sensing
Load 
Resistor
Load 
Sensing
Load 
Resistor
Load 
Sensing
x2
x2
x2
+42Vdc Bus 
Voltage
TPST, 1 
DI
TPST, 1 
DI
TPST, 1 
DI
TPST, 1 
DI
DC DRIVE
Bus 
PTs
x2
Bus 
PTs
x2
Bus 
PTs
x2
Bus 
PTs
x2
CAS HVH P ow Power Testbed
Battery
DC AC
Inverter Board
+42Vdc Bus 
Voltage
Battery
DC AC
Inverter Board
+42Vdc Bus 
Voltage
Battery
Phase A,B 
Currents
Phase A,B 
Currents
CAS HVHEP System Benefits/Challenges
• Direct coupling of generator and propulsors significantly reduces power processing
• Cyclic Energy delivery provides natural commutation of current with each half cycle
• Transformer enables low voltage/high frequency switch mode power electronics
• AC field excitation eliminates remnant field enabling fast deactivation 
• Switched doubly fed machine enables recovery from large disturbances (bird strike)
• Small disturbance recovery and variable speed operation of distributed propulsors achieved 
via ac field excitation and super/sub-synchronous operation of generators and propulsors
– 60% differential speed for two engine aircraft
• Develop dynamic propulsion control (turbine, generator, protection, propulsor, fan/propeller, 
vehicle attitude)
• Develop integrated vehicle and propulsion model/simulation (turbine, generator, protection, 
propulsor, fan/propeller, vehicle attitude, thermal) 
• Develop high speed, high frequency brushless doubly fed electric machine
AC Electrical System and DFIM Benefits
AC Electrical System and DFIM Challenges
Variable Frequency Power System
Initial Operation of low power 
testbed
Stable control of variable frequency 
power system with DFIM
Minimum power electronic conversion 
for high efficiency and low weight
Settingless Protection
Convergent Technologies
• Advanced Modular Power System 
digital control technology 
• SSF differential protection zones for 
rapid detection and isolation of faults
• Ion engine zero energy fault clearance 
technology
FPGA
Sensors
Driver
Switch
Digital Analog
ADC
DAC
Fr
om
 S
ou
rc
e
To
 Lo
ad
Telemetry & Control
AMPS Digital Switchgear
Differential 
Protection
+ ‒Iin Iout
Trip Trip
Power 
Switch
FPGA
+
IinTrip
‒
Iout
I/F
Power 
Switch
FPGA
+
IoutTrip
‒
Iin
I/F
CAN Power Databus
Digital 
Differential
Protection
Iin Iout
Fault
HVHEP Protection
• Minimize aircraft collateral damage through fast detection and isolation of electrical faults
• Digital technology provides light weight implementation for distributed protection system, with superior noise 
filtering and immunity
• Protection system response time includes sensing, transfer of  local data, data processing, field deactivation for 
generators and propulsors, and switchgear operation
• Protection testbed used AMPS digital switchgear in PDU with CAN data bus interconnection
• 3700 ns. response  shows feasibility of digital differential zones with zero energy fault clearance and headroom 
for data checking and redundancy
Setting less protection system with zero energy fault clearance
Remaining Gates/Milestones
• Collaboration activities with Gore Industries and Mersen provides wire and cable 
manufacturing expertise
• LaRC materials testing provides experimental data for detection and healing of 
breakdown events to enable incorporation into protection system 
• GRC 12MW variable frequency power system with DFIM’s provides high power test 
data for scaling law development
• Rolls Royce RTAPS report used for comparative analysis
Manufacturing approach for MFIS Validate scaling laws for variable frequency 
ac power system with DFIM
Monitoring concept for detection of 
insulation breakdown events
Scaling laws applied to N+3 for use in 
system comparative analysis 
HVHEP Technical Solutions Beyond Feasibility
• Develop brushless high power, high frequency, high voltage 
doubly fed electric machine for propulsor application
– Balcones Technologies/University of Texas-Center for Electro-Mechanics
– Challenge: High specific power machine with large rotor/stator pole ratio and 
step up transformer isolated field excitation power inverter
• Develop distributed turbo-electric propulsion control to provide 
dynamic stability
– New Electricity Transmission Software Solutions/MIT
– Challenge: Integrated control of turbine engine, generator, protection system, 
propulsor, ducted fan/propeller, vehicle attitude
• Develop distributed propulsion model/simulation
– Paul C Krause and Associates
– Challenge: Integrated real time simulation of turbine engine, generator, 
protection system, propulsor, ducted fan/propeller, vehicle attitude, thermal


High Voltage Hybrid Electric Propulsion (HVHEP) Activity

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server