Edm E Drive Orlando Conf Mar2009 V14b

EDM Resources Inc.EDM Resources Inc.Harmonic Drive Motor-Generator TechnologyHarmonic Drive Motor-Generator Technology

E. Davison PhD. PEng. Orlando March, 2009

A New Approach To: A New Approach To: High Torque, Variable, Low SpeedHigh Torque, Variable, Low Speed

Motor Generator TechnologyMotor Generator Technology

2Harmonic Drive Motor-Generator Harmonic Drive Motor-Generator TechnologyTechnology

EDM Resources Inc.EDM Resources Inc.

WARP, high torque, High Efficiency High Torque Motor, Navy, electrification, aircraft flap actuator, replace hydraulics, wheel motor, nose motor, harmonic drive motor, harmonic motor, davison, patent

1. Introduction2. Harmonic Motor Technology Primer3. EDM Resources Harmonic Drive Motor4. Applications & Benefits5. Summary6. Q&A

Overview / Outline

Overview / Outline

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1. Introduction

• EDM Resources Inc. Background Based in Moffat Ontario Canada since June 1998 Sole assignee of related patents Contact: [email protected]

• E. Davison PhD, PEng

President and founder of EDM Resources Sole inventor of related patents Developer of innovative high torque density motor-generator

technology since 1965

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mailto:[email protected]




2. Harmonic Motor Technology Primer

• Harmonic Drive Motor-Generator Technology Combination of harmonic gear and reluctance motor technologies Major claimed benefits of HDMG technology:

High torque & power density Lower cost - reduced parts count Rugged construction, high reliability (stationary rotor) Independent control of: torque, speed & position Tolerant of repeated impact torque High torque2 / low rotational inertia ratio Four quadrant operation, plus regenerative braking (without relays)

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• Harmonic Gears Developed by C.W. Musser in 1950’s Harmonic Gears provide unique advantages such as:

Compact & light weight High Reduction Ratio in a Single Stage (30:1 to 300:1) High Torque Capability (up to 50% of teeth in mesh) High resistance to repeated impact torque Low tooth contact pressure & wear Tooth contact is surface as opposed to line contact (no Hertzian stress) Zero Backlash

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• Harmonic Gear vs Other Gear Types

Ref “Gear Design and Application by N. Chironis, ISBN 0070107874 ”

Characteristic Harmonic

GearEpi-

cyclicHerring

boneSingle Worm

Helical Worm

1 Speed Ratio 100 97 96 108 1002 Efficiency (%) 82 85 85 40 783 # of Gears 2 13 4 2 44 # of Bearings 2 17 6 6 65 Pitch line velocity (ft/min) 18 1,500 1,500 1,500 1,5006 Tooth sliding velocity (ft/min) 28 2,500 2,500 1,500 2,5007 Tooth contact pressure (psi) 605 50,000 50,000 5,000 50,0008 Teeth in contact (%) 50 7 5 2 39 Safety factor 36 3 2 2 210 Height (in) 6 13 14 23 1611 Length (in) 6 15 20 19 1712 Width (in) 6 13 10 14 1013 Cubic volume (in3) 216 2,500 2,800 6,100 2,70014 Weight (lb) 30 246 280 230 20515 Tooth contact Surface Line Line Line Line16 Quiet operation Yes No Yes Yes Yes17 Balanced forces Yes Yes No No No




(# flex spline teeth - # circular spline teeth)# flex spline teeth


• Harmonic Gears Principle of Operation 2 closely spaced concentric splined interfacing gears with the

number of teeth on the inner gear being fewer in number than the outer gear

An elliptical cam wave generator causes a fraction of the teeth to mesh at 2 opposite poles with up to half of the teeth being in contact

Reduction ratio =

Image courtesy of Harmonic Drive LLC

Reduction Ratio = (200 – 202) = 100:1 200

(Variable Between 30:1 to 300:1)

Motor Shaft Input

Circular Spline Gear

Flexispline Gear

Elliptical Cam Wave Generator

Image courtesy of wikipedia.org

http://en.wikipedia.org/wiki/Harmonic_drive

http://www.harmonicdrive.net/reference/operatingprinciples/





•Switched Reluctance Motor Principle of Operation SRM invented by Davidson (Scotland, 1838) Rotation & torque achieved by energizing the stator coils sequentially Rotor position determines which coils are

energized (commutation is critical) Field & rotor rotate in opposite directions # of rotor poles must be different from

# of stator poles to avoid starting problems # of working strokes/rev = 24

(for 8 stator poles & 6 rotor poles)

8/6 4 phase SRMImage courtesy of Switched Reluctance

Motor Drives By Ramu Krishnan

Controller&

Commutator





•Switched Reluctance Motor Principle of Operation Benefits

Good stall endurance Fault tolerant & reliable High torque to inertia ratio (acceleration) Lower cost due to robust construction

& ease of manufacture High torque density Ability to withstand higher

temperature environment

Speed

Torq

ue

Typical SRM Torque-Speed Curve(Harmonic Drive Motor-Generator Similar)

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3. EDM Resources Harmonic Drive Motor

• EDM Resources Harmonic Drive Motor Covered by US (7,453,176) and WPO (WO/2004/025815) patents Sometimes referred to as “High Efficiency High Torque WARP Motor” Fundamental difference between EDM HDMG and other

electrical motors: Only motor technology exploiting the large radial

force which is 20+ times that of the tangential torque force

“For example, an 8/6 SRM with a ratio of radius to air gap equaling 100, the ratio between the radial and tangential forces is found to be 26.19; therefore, the radial force is always multiple times that of the tangential force in the SRM and the same can be said for other electrical machines.”(ref Krishnan: Switched Reluctance Motor Drives: Modeling, Simulation, Analysis, Design, and Applications ISBN 0-8493-0838-0, CRC Press 2001, p356 section 7.2.1.1 )

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http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.htm&r=1&p=1&f=G&l=50&d=PTXT&S1=(davison.INNM.+AND+moffat.INCI.)&OS=in/davison+and+ic/moffat&RS=(IN/davison+AND+IC/moffat)

http://www.wipo.int/pctdb/en/wo.jsp?wo=2004025815





• EDM Resources Harmonic Drive Motor Major differences between EDM HDMG and other electric motors

High torque density Traditional rotor is replaced by a stationary (non rotating) element Stator windings occupy space normally occupied by traditional rotor No rotor = no rotor inertia or windage Unipolar DC pulse excitation – minimal flux reversal and iron losses Independent concurrent control of: torque, speed and position

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Fr = 20 x Ft

+Ft

Very Large Radial Force Fr(replaces elliptic cam wave generator)

Harmonic Gearing (100:1)

= Very High Torque Density





• Motor Construction (experimental prototype)

Flexispline (Rotatively Fixed with internal teeth)

Stator Windings (replaces elliptical cam wave generator)

Output spline gear/flange (with external teeth)Bearings (2)

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• Motor Construction – Single Output (two alternatives)Flexispline- Teeth on insideOutput gear rotation direction - opposite to field rotation

Output gear (rotates)

Bearings (2)Windings

Flexispline- Teeth on outsideOutput gear rotation direction - same as field rotation

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• Motor Construction - Continuous Through Shaft Applications: ship propulsion, aircraft wing flap actuators, electric

power assist steering

Continuous through shaft construction or linear screwMotors coupled in series for minimized packaging with high torque density or distributed high torque

Output gear (rotates)

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• Motor Forces Force is generated by rotating electromagnetic field Rotational sequence: A B C

Flexispline Gear Fixed (teeth on inside)

Circular Spline Gear Rotates (teeth on outside)

A

B

C

Field Rotation

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• Principle of Operation – Switched Reluctance Version (4 phase – 2 pole) Two energized coils in series

(but of opposite polarity) 8 stator coils in total Flux flow does not rotate

but is switched to next coilin sequence

Flux return path throughflexispline

# of equivalent rotor poles = # of stator poles,therefore # of working strokes / output rev = 16 x N(N = harmonic gear ratio)

Flexispline

Stator Core

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• Principle of Operation Simulation of flux flow

distribution No outside back up iron

ring or laminations Thick flexispline cup Magnetic flux is confined

mainly to local flexisplinequadrant (lower iron losses)

Excitation unipolar DC pulses (no flux reversal – reduced ironlosses)

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Radial force Fr =

A = Air Gap (4 x ½ = 2in2)

Bg = Air Gap Flux Density

μo = 4 x10-7 (permeability)

Fr = 250 lbs/in2 x A (for Bg 2.1Tesla)

Total Radial Force Ftr = 3/2 Fr x 2 x A = 3 Fr x A = 3 x 250 x 2 1500 lbs

Torque Translation ModelFtr = Total Radial ForceTo = Output TorqueR = Torque Radius (4”)

α = Gear Tooth Angle

N = Harmonic Gear Ratio 100:1

Ki = Mitigating Factors (K1...Kn)

A Bg2

2 μo

Example Core Lamination Stack

To

Ftr

To = Ki x N x Ftr x R = Ki x 100 x 1500 x 4 = 600,000 x Ki (lbs-in)

MeshingGear Teeth

8”

4”

½”

Fr

Fr

Fr4

Fr4

Fr4

Fr4

• Harmonic Motor – Potential For Torque Production

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• S.R. Motor Controls Adaptable To Harmonic Motors





• Experimental Prototype Motor

Windings stationary Flexispline

(rotatively fixed & electromagnetically distorted to engage

rotor output gear)

Output gear rotates

Internal gear teeth

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• EDM Resources Harmonic Drive Motor Experimental Prototype Motor gear teeth

Rotor teeth not engaged – rotor free wheeling

Rotor teeth engaged – rotor locked

(Can be clutched & de-clutched)

(Very high locking torque)

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• EDM Resources Harmonic Drive Motor Video

3. EDM Resources Harmonic Drive Motor 2009©

Click on icon to play motor video




4. Applications

• EDM Resources Harmonic Drive Motor Applications Navy electrification – ship propulsion & electrical energy generation

system Multi-screw propulsion

(with continuous through shaft motors) Benefits:

– Load diversification» Some units produce torque, some generate electrical energy,

or all units produce propulsion torque,or all units generate electrical energy

» Avoids peak load design for separate generator and propulsion systems » Redundant system with high reliability

– Ability to use super conducting stator windings for increased efficiency– Reduces transmission gear requirements– Reduced cost, simplified maintenance & reduction in highly trained personnel

Replace hydraulic & pneumatic actuators

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4. Applications

•EDM Resources Harmonic Drive Motor Applications Military applications

Actuators (turret, fire control) Traction (wheel motors) Winches Power Steering

Benefits High torque density High controllability Replaces hydraulics High reliability (robust) Lower weight Low maintenance Resistant to impact Facilitates liquid cooling

Traction System Actuation




4. Applications• EDM Resources Harmonic Drive Motor Applications

Aerospace applications Actuators

– Wing flaps, landing gear Aircraft

– In nose wheel tow motor (for reducing fuel consumption during taxiing) Robotics Satellites

Benefits High torque density High distributed torque Lower weight & inertia High precision (30:1 to 300:1) Replace hydraulics Redundant system High reliability Low maintenance Fail safe operation Resistant to impact Facilitates liquid cooling

Conceptual design for applying harmonic drive motors to aircraft leading flap actuator to replace hydraulic actuatorsSingle output HDMG Multiple through-shaft

HDMG motors in series




4. Applications

• EDM Resources Harmonic Drive Motor Applications Wind turbines

Low weight integral gear generator Low speed propulsion drives

Air ship propulsion Benefits

High reliability High torque at low speeds Low weight / reduced mounting

column requirements Low maintenance Compact Reduces transmission

gear requirements Rotor can free-wheel

or be locked




•EDM Resources Harmonic Drive Motor Applications Automotive Applications - Continuous through shaft HDMG motor

Electric power assist steering (pinion, column, rack mounting) Sliding door & lift gate actuators

Benefits High torque density – enabler for heavy truck EPAS Programmable “feel”, speed sensitive variable assist High reliability & fail safe operation Low cost Minimal package space Replaces hydraulics Low weight Low maintenance

4. Applications

Continuous through shaft HDMG motorIntegrated into steering system

Column Mount

Rack Mount




• Summary EDM Resources harmonic drive motor generator:

U.S. & WPO patents Only known motor technology that exploits the large radial force which is 20+ times

that of the tangential torque force and an integral harmonic gear Working prototype – proof of concept

Benefits: High torque density Lower cost construction (SRM, fewer components count) Multi configuration (single output shaft or continuous through shaft) Integral harmonic gearing with high single stage reduction (30:1 to 300:1) Independent concurrent control of: torque, speed and position High reliability (fewer moving parts, up to 50% of gear teeth in mesh)

Enabler for: Electrification for: military, aerospace, robotics, automotive, machine tools Replacing hydraulic or pneumatic actuators Cost & weight reduction vs hydraulics & other motor-gear systems

5. Summary2009©




6. Questions

Questions?

Edm E Drive Orlando Conf Mar2009 V14b

Entertainment & Humor

Transcript of Edm E Drive Orlando Conf Mar2009 V14b