electro hydrostatic actuators for control of undersea · pdf fileelectro hydrostatic actuators...

NDIA-6240 - 2006 Stephen Smith

Slide 1

Joint Undersea Warfare Technology Fall ConferenceSeptember 11-14, 2006 US Naval Submarine Base New London

Joint Undersea Warfare Technology Fall ConferenceUS Naval Submarine Base New London

Groton, ConnecticutSeptember 14, 2006

Electro Hydrostatic ActuatorsFor Control of Undersea Vehicles

Presented by: Jerry IrvingWritten by: Stephen Smith, P.E.


Slide 2


Introduction

• This presentation will cover– Principals of Electro Hydrostatic Actuator (EHA)

operation– History of EHA’s– EHA Advantages– EHA Disadvantages– Two Fault Tolerant EHA System– Conclusions– Recommendations for Future Studies


Slide 3


Introduction

• The Navy desires to convert from hydraulic actuation to electric actuation

• Submarines are in the early stages of converting the ship’s hydraulic actuators to electric

• Full benefits of the conversion can only be realized when the hydraulic plant is eliminated.

• Some applications may not lend themselves to conversion due to envelope, force or other operating restrictions

• In these cases, electro-hydrostatic actuation (EHA) could provide a “more electric” approach.


Slide 4


Typical Hydraulic System

Reservior

Motion Controller

Motor Starter

ServovalvesCheck valves

Hydraulic Motor

Linear Actuator

Manifold

ChillerRetrun Filter

High Pressure Filter

Pump motor & pump

Generic Hydraulic System

Reservior vent


Slide 5


Electro Hydraulic Features

•Mature technology with skilled technicians

•Low to high pressure systems

–Allows matching of pressure/flow to address envelop and output force

•“Battle”/emergency conditions

–Allows operation of critical functions

–Moves to safe position on power loss


Slide 6


Electro-Mechanical Actuation System

• Actuator– Brushless DC Motor

– Gear Set

– Ball or Roller-Screw Output– LVDT Position Feedback

• Controller– Servo Control Board

• Closed Loop Control

• Command and Telemetry Interface

• Signal conditioning

– Gate Drive Board• Output Stage to drive electric motor

– Power Supply Board• Low voltage power supply• EMI Power Filter

• Electrical Cables


Slide 7


Electro-Hydrostatic Actuation System

• Actuator– Brushless DC Motor– Fixed Displacement Hydraulic Pump– Hydraulic Piston-Cylinder Assembly– LVDT Position Feedback

• Controller– Servo Control Board

• Closed Loop Control• Command and Telemetry Interface • Signal conditioning

– Gate Drive Board• Output Stage to drive electric motor

– Power Supply Board• Low voltage power supply• EMI Power Filter

• Electrical Cables


Slide 8


Actuation System Heritage

1951 Moog FoundedHydraulic Servovalve

• Minuteman• Polaris• Atlas• Saturn• Terrier Tartar• Pershing• Titan II, III

• Space Shuttle

SRB & Orbiter

• Trident C4

• Peacekeeper

• Titan

• Jupiter

• Atlas

1982 Entered Electro-mechanical Actuation Market

• Ariane 4

• Ariane 5 (EM)

• Trident D5

• SM2 (EM)

• SRAM II (EM)

• Titan IV• Atlas III/V (EM)• Delta 4 (EM)• Delta IV SRB• Pegasus (EM)• Kistler K-1 (EM)• GMD (EM)• X-38 CRV (2FT EM)

1999 – Developed Two-Fault Tolerant Electro-mechanical Actuation.

2000 – Developed Electro-hydrostatic Actuation

2002 – Develop Two-Fault Tolerant Electro-hydrostatic Actuation

1950’s 1960’s 1970’s 1980’s 1990’s

• NGLT

• 2GRLV (2FT EHA)

• X-43A (EM)

• Next Gen ICBM

2000’s

1951 Moog FoundedHydraulic Servovalve

• Minuteman• Polaris• Atlas• Saturn• Terrier Tartar• Pershing• Titan II, III

• Space Shuttle

SRB & Orbiter

• Trident C4

• Peacekeeper

• Titan

• Jupiter

• Atlas

1982 Entered Electro-mechanical Actuation Market

• Ariane 4

• Ariane 5 (EM)

• Trident D5

• SM2 (EM)

• SRAM II (EM)

• Titan IV• Atlas III/V (EM)• Delta 4 (EM)• Delta IV SRB• Pegasus (EM)• Kistler K-1 (EM)• GMD (EM)• X-38 CRV (2FT EM)

1999 – Developed Two-Fault Tolerant Electro-mechanical Actuation.

2000 – Developed Electro-hydrostatic Actuation

2002 – Develop Two-Fault Tolerant Electro-hydrostatic Actuation

1950’s 1960’s 1970’s 1980’s 1990’s

• NGLT

• 2GRLV (2FT EHA)

• X-43A (EM)

• Next Gen ICBM

2000’s


Slide 9


F18 Stabilator EHA

• 30,000 lbs nominal stall force

• 400 in/sec2 maximum no-load acceleration

• 8.5 in/sec maximum no-load velocity

• 7.12 in total stroke (34.0 in pin-to-pin mid-stroke)

• 23 hp maximum output power (39 hp corner)

• Easily met 5 Hz response requirement (capable of much higher)

• >225,000 lbs/in infinite-frequency stiffness (one actuator piston bypassed)


Slide 10


EHA Advantages

• Power on Demand – No power required when unit is not in use. Improves

system level efficiency. – Pressure is only developed in response to static loads

or accelerations

• Independent of the ships hydraulic system.– Self-contained hydraulic supply & return porting– Limited fluid contamination & leakage concerns– Capable of operating at higher internal pressures

• No backlash, lost motion as with geared systems

• Heritage hydraulic piston cylinder assembly


Slide 11


EHA Advantages

• “Gear reduction” is obtained by reducing the size of the

pump, facilitating the use of small, low-torque servomotors.

• Snubbing is easily handled with relief valves.

• Mechanical packaging is more flexible.

– Facilitates a distributed control surface arrangement

• Can be made to be Fault Tolerant

– Allows depth control to be triple redundant


Slide 12


EHA Advantages

• Redundancy and fail-safe features have minimal impact on

cost, weight, envelope, and reliability.

– Float and Lock of control surface

• PM Motor allows variable speed operation of fixed

displacement pump.

• Lower maintenance

• Improved reliability

– Greater control authority under fault conditions

• Lower cost of ownership


Slide 13


EHA Disadvantages

• Lower efficiency due to multiple power conversions

• Pump sizing may result in undesirable weight and envelope.

• Reservoir sizing critical.• Hydraulic fluid is not completely removed from

the ship. • Varying pump/motor operating conditions (i.e.

varying speed and pressure).


Slide 14


Two-Fault Tolerant EHA System

Thrust Vector Control


Slide 15



• Quad Bi-Directional Electric Motor-Hydraulic Pump Control– Flow summed from fixed displacement

hydraulic pumps– Full performance produced after two faults

(two active channels)

• Quad Channel LVDT for Actuator Position

Control Electronics UnitMotor Control Unit

Quadruplex EH Actuator


Slide 16



Controller Architecture• 4 Independent Motor Control Units (one per channel)• 4 Independent Control Electronics Units (one per

channel)• Independent Channel Pressure Transducers

– Load resonance damping

• Independent Resolver Commutation– Closed loop motor velocity control

• Quad LVDT Provides Independent Position Loop Closure• Cross-Port Load Relief Valves for Transient Motor Start• Blocking Valves Isolate Failed Channels

– Eliminating potential drag torque from failed channel– Can be used to maintain the last commanded position


Slide 17



RESERVOIRRESERVOIR RESERVOIR RESERVOIR

MANIFOLD

MCU

CEUChannel 1

3

BLOCKING VALVE

PUMP MOTOR R

PCASEDRAIN

1553

DISCRETESHUTDOWN

BC

RT

1553FCC

MCU

CEUChannel 2

3

BLOCKING VALVE

PUMP MOTOR R

PCASEDRAIN

1553

DISCRETESHUTDOWN

BC

RT

MCU

CEUChannel 3

3

BLOCKING VALVE

PUMP MOTOR R

PCASEDRAIN

1553

DISCRETESHUTDOWN

BC

RT

MCU

CEUChannel 4

3

BLOCKING VALVE

P

PUMP MOTOR R

PCASEDRAIN

1553

DISCRETESHUTDOWN

BC

RT

QUADLVDT

270 Va

28 Vd28 Vc28 Vb28 Va

EMIFilter

270 Vb

EMIFilter

270 Vc

EMIFilter

270 Vd

EMIFilter

RT RTRTRT

BC

CCDL CCDL

CCDLCCDLCCDL

P

TELEMETRY

CYLINDERPRESSURE

CYLINDERPRESSURE

LEVELSENSE

LEVELSENSE

LEVELSENSE

LEVELSENSE

CCDL

RTD RTD RTD RTD

RTD RTD RTD RTD

IVHM IVHM IVHM IVHM

PPPPPPP

P

TELEMETRY


Slide 18


Two-Fault Tolerant EHA System• Flow output summed

equally over active channel quantity

• FDIR Step Response (4 to 3 to 2 Channel)– Motor-Pump Assembly

rotor speed as channel faults are detected and isolated

– Motor Current Draw also due to higher winding losses

– Position command maintained

– Actuator output load maintained

Actuator Step Position Command

0-Fault, 4-Channel Motor-Pump Velocity Feedback



2ndC

hann

el F

ailu

re

1stC

hann

el F

ailu

re

Actuator Step Position Command




2ndC

hann

el F

ailu

re

1stC

hann

el F

ailu

re


Slide 19





2ndC

hann

el D

ropp

ed

Cross-Channel Velocity Mis-Match Identified



2ndC

hann

el D

ropp

ed

Cross-Channel Velocity Mis-Match Identified


Slide 20


Two-Fault Tolerant EHA SystemParameter TVC System Capability

Actuator Null Length 51.37 in Total Stroke >10 in Stall Force 75,000 lbf Power Point Slew Rate 5 in/sec Power Point Force Output 66,000 lbf Peak Power Output 50 HP Impulse Load (for 50 msec) 160,000 lbf Supply Voltage <270 VDC TVC Duty Cycle Duration per Mission ( > 100 Flight Missions)

500 sec

Frequency Response (@ p-p cmd) 0.42 in Frequency Response (-3db amplitude) 6 Hz Hydraulic Piston Area 24.6 in² Hydraulic Pump Displacement (per unit) 0.410 in3/rev Hydraulic Pump Mechanical Efficiency 0.85 @ power point Hydraulic Pump Volumetric Efficiency 0.88 @ power point Motor Current Limit 140 Amps rms (200 Amps peak) Electrical Interface Mil-Std 1553 Serial


Slide 21



Parameter NormalOperation 2-Failure Operation Power Point Operation

• Slew Rate • Force Output • Pressure Differential @ Pump • Motor Shaft Torque • Motor Speed • Motor Peak Current

• 5.0 in/sec • 66,000 lbf • 2798 psid • 205 in-lbf • 5343 rpm • 148 Amps peak

• 5.0 in/sec • 66,000 lbf • 3098 psid • 236 in-lbf • 10229 rpm • 178 Amps peak


Slide 22


Conclusions

• “More” Electric Actuation is a viable alternative to mechanical feedback and servo-valve commanded hydraulic actuation.

• Aerospace industry has moved to “more” electric actuation systems– Simplify integration and support– Reduce life cycle cost

• Technology development efforts have demonstrated capability to Technology Readiness Level (TRL) of 6

• Decision to implement “more” electric actuation will be a system-level trade including power systems


Slide 23


Future Studies

• Noise Evaluation– Pump Configurations– Motors– Controllers


Slide 24


Future Studies

• Pump Configurations– Slower Speeds– Piston Pump

• Tend to be noisy

– Screw Pump • Typically unidirectional

– Gear Pump – Vane Pump

• Inherently quiet and bi-directional


Slide 25


Motor Design

• High Torque Density

• Slow Speed– Six step Trapezoidal BEMF – relatively noisy– Sinusoidal BEMF – smooth commutation

-1.5

-1

-0 .5

0

0 .5

1

1.5

Classical Sine WaveSix Step Sine Wave


Slide 26


Controller Design

• Sine Motor Drive• Compliant to Mil-Std-1399 Class 1 Power

– Harmonic Requirements– Mil-Std-461 Compliance

• High Fidelity Output Current Control– Designed to meet harmonic, distortion, offset, and imbalance

requirements that are required to provide submarine level acoustic requirements

• Small Size and Weight– Allows for remote or integral packaging approach

• Rugged Design Suitable for Shipboard– Shock, Environments (MIL-S-901D) – Designed with Naval requirements in mind rather than upgraded

from an industrial design


Slide 27


Electro Hydrostatic Actuators

Thank You

Questions

electro hydrostatic actuators for control of undersea · pdf fileelectro hydrostatic actuators...

Documents