The document describes a new motor-generator technology called the Harmonic Drive Motor-Generator (HDMG) developed by EDM Resources Inc. The HDMG combines harmonic gear and switched reluctance motor technologies. It has several potential advantages over traditional electric motors including higher torque density, independent control of torque, speed and position, and higher torque to inertia ratio. The motor replaces the traditional rotating rotor with a stationary flexspline and uses the large radial forces in switched reluctance motors to turn an output gear through a harmonic gearing mechanism.
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Edm E Drive Orlando Conf Mar2009 V14b
1. EDM Resources Inc.
Harmonic Drive Motor-Generator Technology
A New Approach To:
High Torque, Variable, Low Speed
Motor Generator Technology
E. Davison PhD. PEng.
Orlando March, 2009
6. EDM Resources Inc.
2. Harmonic Motor Technology Primer
• Harmonic Gear vs Other Gear Types
Harmonic Epi- Herring Single Helical
Characteristic Gear cyclic bone Worm Worm
1 Speed Ratio 100 97 96 108 100
2 Efficiency (%) 82 85 85 40 78
3 # of Gears 2 13 4 2 4
4 # of Bearings 2 17 6 6 6
5 Pitch line velocity (ft/min) 18 1,500 1,500 1,500 1,500
6 Tooth sliding velocity (ft/min) 28 2,500 2,500 1,500 2,500
7 Tooth contact pressure (psi) 605 50,000 50,000 5,000 50,000
8 Teeth in contact (%) 50 7 5 2 3
9 Safety factor 36 3 2 2 2
10 Height (in) 6 13 14 23 16
11 Length (in) 6 15 20 19 17
12 Width (in) 6 13 10 14 10
3
13 Cubic volume (in ) 216 2,500 2,800 6,100 2,700
14 Weight (lb) 30 246 280 230 205
15 Tooth contact Surface Line Line Line Line
16 Quiet operation Yes No Yes Yes Yes
WARP, high torque, High Efficiency High Torque Motor, Navy, electrification, aircraft flap actuator, replace hydraulics, wheel motor, nose motor,
17 Balanced forces
harmonic drive motor, harmonic motor, davison, patent Yes Yes No No No
Ref “Gear Design and Application by N. Chironis, ISBN 0070107874 ”
Harmonic Drive Motor-Generator Technology 6
7. EDM Resources Inc.
2. Harmonic Motor Technology Primer
• 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 = (# flex spline teeth - # circular spline teeth)
# flex spline teeth
Reduction Ratio = (200 – 202) = 100:1 Circular Spline Gear
200 Flexispline Gear
(Variable Between 30:1 to 300:1) Elliptical Cam
Wave Generator
Motor Shaft
Input
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
Image courtesy of wikipedia.org Image courtesy of Harmonic Drive LLC
Harmonic Drive Motor-Generator Technology 7
8. EDM Resources Inc.
2. Harmonic Motor Technology Primer
• 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 Controller
&
(for 8 stator poles & 6 rotor poles) Commutator
8/6 4 phase SRM
Image courtesy of Switched Reluctance
Motor Drives By Ramu Krishnan
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
Harmonic Drive Motor-Generator Technology 8