© ricardo plc 2007 confidential - internal use only automotive hybrid experience applied to...

© Ricardo plc 2007 CONFIDENTIAL - Internal Use Only

Automotive Hybrid ExperienceApplied to Electric Aircraft Design

byMarc W. Wiseman, Ph.D., Divisional Product Group Director, Advanced Technology

and James C. Paul, P.E., Senior Engineer and Business Development ManagerRicardo, Inc.

Electric Aircraft Symposium

Westin Hotel, Millbrae, California

23 May 2007

http://www.designation-systems.net/dusrm/app2/q-7.html www.cafefoundation.org

NASA PAV Concept

Shadow 200 UAV


NASA PAV Concept

Shadow 200 UAV

The automotive industry has made significant progress in the area of electric vehicle (EV) and hybrid-electric vehicle (HEV) drive systems.

This experience can be leveraged to support development of electric and hybrid-electric PAVs and UAVs.

Energy storage, on-board power generation, vehicle modeling and integration, electric machines, and controls/power electronics will be discussed.

Possible integration of these technologies into future aircraft designs will be explored.

Automotive Hybrid Experience Applied to Electric Aircraft Design

Thesis

The auto industry has evaluated a wide range of hybrid schemes

Electrical Machines

Power Transmission

Energy Storage

www.evworld.com/press/sandia_lithium-ion.jpg


Automotive Hybrid Experience Applied to Electric Aircraft Design

Company Overview

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4CONFIDENTIAL - Internal Use Only

Ricardo has been involved in hybrid vehicle development since 1999: 1. Proprietary programs for OEMs, component suppliers, government agencies, military.

2. Ricardo internal R&D programs

Ford Escape HEV

Battery /ControlsBattery /ControlsBattery /Controls

Mild Hybrid Full Hybrid Optimum EfficiencyMicro Hybrid

HyTrans Efficient-Ci-MoGen

Military/Off-roadHybrid Refuse TruckUS Government Advanced Hybrid Vehicles

Selected ProjectsGVWs have ranged from 3.5 to 25 tons.

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Projects have spanned the full range of hybridization,from “micro” to “full”

Micro Mild Full Commercial

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Powertrain and Vehicle

Controls and Electronics

Electric Machines, Power Electronics and Energy Storage

Program management

Ricardo’s hybrid experience includes over 120 dedicated

development engineers & consultants

– Production design and release– Vehicle engineering & system simulation– Engine and transmission design and development for hybrids– Prototype and pre-production build

– System simulation– Control strategy development– Embedded software development– Software tools– Hardware-in-the-loop application

– Motor development – Electronic hardware (including power electronics) development and

validation – Energy storage modelling, test and validation

– Current technology analysis– Market characteristic assessment– Opportunities assessment– Technical trend assessment– Program planning business case development– Program support & guidance

Capabilities

Ricardo is experienced in developing corporate strategies for hybrid vehicles

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Ricardo has been actively engaged in advanced energy storage systems and integration into hybrids for over 6 years.

Requirements definition and cost/benefit analyses for EVs, HEVs and PHEVs

Mechanical design for vibration, shock and crash

Pack design for cost, assembly and manufacture (DFx)

Thermal design, analysis, development and validation

Simulation and test, validation of battery system

Control algorithm and software development for SOC/SOH

Battery Management System (BMS) hardware design and validation

Safety system integration, FMEA, and Hazard Analysis

Supply chain management of subsystems

Prototype manufacturing, validation and launch support

Ricardo currently studying market potential for establishing a Center of Excellence for Energy Storage development in Michigan

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Status of Automotive Hybrid Technology

Five OEMs have hybrid products on the market. Many offer more than 1 vehicle and most are working on at least their second generation of hybrid technology.

Hybrids vehicles are low volume – key focus is on production quality of hybrid components to avoid warranty costs. Production targets include:

– Design for less than 100 ppm failures in vehicle (i.e zero failure).– Design for 150k miles / 10 year life (equates to over 7500 hrs of operation time)– Robust to significant vibration and shock forces.– Robust to thermal temperature extremes.

NiMH batteries are proving to have good cycle life and good calendar life.

Lithium ion technology is being actively developed for next generation hybrid batteries.

Good understanding is being gained of potential operating failure modes for hybrid systems and mitigation strategies.

Toyota Prius Honda Civic Ford Escape Saturn Vue Nissan Altima

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Ricardo’s Current Aerospace Activities

Aviation Week & Space Technology April 2, 2007

Wide range of applications, 1hp to 1000hp– “Backpack” engine for suit cooling/local power– “Powerpack” handheld genset engine– Several UAV engine concepts, including High

Altitude– UAV heavy fuel engine demonstrator– Helicopter powerplant concept for extended

range

Focus on Unmanned Aerial Vehicles

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Ricardo’s Current Aerospace Activities

UAVs span a wide size range, including sizes appropriate for PAVs

• Military applications are a primary driver for the UAV industry.

• Current goals are:

1. Increased Endurance

2. Reduced Noise

3. Operate on Available Fuels

4. Increased Payload Capacity

5. Reduced Maintenance

6. Improved Durability

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Approach to Electric/Hybrid Aircraft Design

Perform mission requirement/energy requirements trade-off studies using:

Classical analysis (spreadsheets)

Computer simulation

MSC.EASY5

– MSC.EASY5Ricardo Powertrain LibraryRicardo Engine LibraryRicardo Fuel Cell LibraryRicardo Electric Drive Library

Available libraries allow simulation of a wide range of power system designs to facilitate selection and sizing of components.

Full-Throttle Power Available

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From: Dommasch Airplane Aerodynamics, Fourth Edition, Page 302

Speeds for Best Range and Endurance for Propeller-Driven Aircraft

Power Required CurveBest Endurance Speed = Speed at Minimum Power (maximum time in air)

Best Range Speed = Speed at Which the Ratio HP/V is a Minimum (the speed giving the greatest ratio of velocity to horsepower required).

Assumes the thrust specific fuel consumption (lb/THP-hr) is essentially constant over the low HP range.

Backside of power curve: if speed is decreased, power must be added to hold altitude

Design Propulsion System Based on Minimum Energy Mission Approach (takeoff, dash, cruise)

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TOOLS– Matlab Simulink, EASY5

Ricardo Powertrain Library for SimulinkV-SIM (IPT)Ricardo Engine Simulation Libraries

CAPABILITIES Duty Cycle Simulation (fuel consumption and

emissions) Performance Simulation (Climb, Dash, Top Speed) Co-simulation with WAVE, FLOWMASTER, etc.

Drive Cycle Simulation of Mild Hybrid Diesel-Electric Pickup TruckDrive Cycle Simulation of Mild Hybrid Diesel-Electric Pickup Truck

0 100 200 300 400 500-50

0

50

100

150

200

250

Drive Cycle Simulation of Mild Hybrid Diesel-Electric Pickup Truck

0 100 200 300 400 500-1E+4

-5E+3

0

5E+3

1E+4

1.5E+4

2E+4

Model: ParallelHybrid, Runid: simulation, Case: 1, Display: 7. 06-FEB-2003, 10:38:34

Time [s]

Pow

er [W

]

Motor-Generator Mechanical Power

Time [s]

Torq

ue [N

.m]

Engine Torque


0 100 200 300 400 5000

10

20

30


0 100 200 300 400 5000

4

8

12

16

20

24


Time [s]

MP

G

Average Fuel Economy

Time [s]

Spe

ed [m

/s]

Speed Setpoint Vs Actual Speed


0 100 200 300 400 500-1E+4

-5E+3

0

5E+3

1E+4

1.5E+4

2E+4

2.5E+4


0 100 200 300 400 5000

0.2

0.4

0.6

0.8


Time [s]

Sta

te [0

-1]

Battery State of Charge

Time [s]

Pow

er [W

]

Battery Power

Drive Cycle Simulation of a Light commercial Truck

Motor-generator mechanical power

Engine torque

Set point versus actual speed

Average fuel economyBattery state of charge

Battery powerVEMPS(60Mb project code)

CANTRACKVDU

NEW BOSCH ECU

VALEOFMED CU

VALEOBattery Man

VALEODC/DC conv

WABCOBrake Assist

VALEOHVAC

SmartWater Pump

SmartFans

SmartActuators

OPELhE-PAS

present on car

SmartVNT actuator

SmartEGR actuator

SmartThrot’ actuator

SensorDoors

SensorVehicle Speed

SensorClutch Pedal

SensorBrake Pedal

SensorBonnet

SensorVoltages

Sensors(Many)

Sensors(Many)

K-LinePWM

Analogue

SensorsThermal

SensorsV + Amp

SensorVacuum

Laptop withINCA Calibration

Tool(temporary)

CANALISER(temporary)

CAN

i-MoGen Control System• 14 Micro Controllers / Computers added

• 6 smart actuators or ancillaries

• + 2 temporary calibration tools

OPELABS

present on car

SensorsVoltage

VEMPS(60Mb project code)

CANTRACKVDU

NEW BOSCH ECU

VALEOFMED CU

VALEOBattery Man

VALEODC/DC conv

WABCOBrake Assist

VALEOHVAC

SmartWater Pump

SmartFans

SmartActuators

OPELhE-PAS

present on car

SmartVNT actuator

SmartEGR actuator

SmartThrot’ actuator

SensorDoors

SensorVehicle Speed

SensorClutch Pedal

SensorBrake Pedal

SensorBonnet

SensorVoltages

Sensors(Many)

Sensors(Many)

K-LinePWM

Analogue

SensorsThermal

SensorsV + Amp

SensorVacuum

Laptop withINCA Calibration

Tool(temporary)

CANALISER(temporary)

CAN

i-MoGen Control System• 14 Micro Controllers / Computers added

• 6 smart actuators or ancillaries

• + 2 temporary calibration tools

OPELABS

present on car

SensorsVoltage

Vehicle Control System Development

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One challenge for Electric aircraft is the weight of the energy storage system.

Example Operating Characteristics for UAV

Target Weight 300 lbs [136 kg]

Typical cruise power 6 HP [4.5 kW]

Typical take off power 24 HP [18 kW]

Estimated take off energy 3 kWh

Estimated cruise energy 4.5kWh per hour of flight time.

Estimated Automotive Li-ion Battery Characteristics

Li –ion energy density 80 – 120 Wh / kg

Li-ion max power density 1300 – 1600 W / kg

Li-ion cont power density 800 – 1000 W / kg

Current estimated battery life 5000 flights

For the following example, Lithium-Ion Batteries were Selected as Being Representative of the

Best Currently-Available Technologies for Energy and Power Density

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Battery weight remains a challenge which limits flight time

Calculations based on a 300 lb UAV

The battery pack alone would be 300 lbs for a 3 hr flight

time !!

A holistic approach is needed to improve flight time by finding ways to reduce takeoff and cruise power, take weight out of all components.

Effect of Battery Cell Weight on Flight time

0

100

200

300

400

500

600

700

0 1 2 3 4 5 6 7

Flight time (hrs)

Ba

tte

ry w

eig

ht

(lb

s)

UAV weight !!!

Example

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How can performance be improved if energy storage remains a limiting factor? 1. Reduce drag, CD

2. Reduce weight, W

3. Improve efficiency, CL/CD

4. Change mission profile (e.g. HP vs time history, improved take-off profiles)

5. On-board power generation (e.g. solar cells)

6. Improved energy storage systemsTraditional aircraft design approaches have included trade-offs between efficiency and performance with focus on performance.

Electric aircraft will include similar trade-off studies, but the focus will be on minimizing energy use.

AeroVironment Helios Aircraft with Solar Panels on Wings

http://www.pvresources.com/en/helios.php

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To meet goal of 8hr+ flight time, efficiency improvements and alternative power sources are needed.

Solar Energy Benefit to Flight time

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00

Flight Time (hrs)

So

lar

En

erg

y (

kW

)

100 lb Battery Pack

150 lb Battery Pack

100lb Battery Pack - 50% lower cruisepower

Solar cells alone are not optimum solution

Effort is required to reduce cruise power

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Conclusions

Automotive engineering practice is providing high quality, robust and long life electric motors, electronics and battery systems.

Hybrid road vehicle technology is developing at a rapid pace with particular progress being made in the areas of 1) equipment costs (including manufacturing methods and economies of scale), 2) operational failure modes are well understood and mitigation strategies can be deployed, and 3) weight optimization methods.

Current battery technology presents a challenge for achieving weight targets.

Detailed analysis and a holistic approach to UAV/PAV design is required to meet mission requirements. Modeling tools are available to assist in configuration assessment and component sizing.

Note possible technology development opportunity: DARPA-sponsored Vulture Program (5 year-aloft, 1000 lb solar/battery/fuel-cell powered aircraft).

© ricardo plc 2007 confidential - internal use only automotive hybrid experience applied to...

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