To the list of demands placed on motion technology in the current environment
can be added power density and efficiency. Servomotors based on ThinGap
technology give motion engineers new tools to significantly advance the
performance of the plant floor in every industry. The ThinGap® Brushless
DC Motor exhibits extraordinary power output in a small package.
Stator Coil
With the innovative ThinGap Servo Stator Coil design, the stator is
constructed entirely of non-magnetic, high-temperature-capable materials.
No magnet wire or iron laminations are associated with the stator. The
freestanding structure of the stator coil has no supporting substrate
or iron laminations and is virtually invisible to the magnetic field.
Any heat generated in the stator is readily dissipated with air moving
over both the inside and outside of the thin, freestanding coil.
With over 90% electrical efficiency, the ThinGap Stator Coil converts
most of the input power to shaft power. Since there is no iron in the
stator system, iron losses are eliminated, and less total heat generated.
Cogging is also eliminated, not just reduced. There are no magnetic materials
in the stator to become distorted, demagnetized or saturated with high
peak currents. The Stator Coil's thin wall allows a very narrow magnetic
gap, but with high copper packing density in the magnetic field. The coil
has very low phase-to-phase resistance, giving the system design engineer
new tools to create motors capable of continuous high torque levels.
Servo Rotor
The ThinGap servomotor rotor is constructed to contain the entire magnetic
circuit as it rotates. This design feature eliminates eddy currents or
hysteresis losses in the magnetic materials. With no magnetic hysteresis,
cogging found in old technology servomotors is eliminated. The permanent
magnets and magnetic return structure are fixed on the rotating drive
shaft. The freestanding stator coil is positioned in the very thin air
gap between the magnets and return iron. This design enables the management
of rotating inertia to better match the inertia of the driven load.
ThinGap Servomotor Attributes
- Flat Torque Profile at All Speeds: Torque remains constant
over a wider speed range compared with iron core servomotors, with the
ability to utilize trapezoidal motor drivers that typically do not perform
well with old technology servomotors.
- Wide Speed Control Range: Most servomotors are limited in ability
to operate at both high and low speeds without transmissions. The ThinGap
Servo-Motor achieves 120 in.-oz torque through a speed range of one
revolution per day to 2300 rpm.
- High Rated Power-to-Weight Ratios: High rated power when compared
to any known servomotor's rated power output in watts compared with
the motor weight. Company comparisons show a 2-4 times improvement in
power-to-weight over known servomotors.
- Higher Peak Power: Iron core servomotors have peak power limited
by saturation of the magnetic materials in the rotor and stator coil.
With no magnetic materials in the ThinGap stator coil, there are no
materials to become saturated with high current, which translates to
very high peak power at lower duty cycles. Peak power of the ThinGap
motor can reach more than three times the Rated Power, impractical for
old technology servomotors.
- Smaller Overall Size: Significantly shorter motor length than
any known servomotor with comparably rated power output in watts and
continuous torque in.-oz.
- Ability To Eliminate Gearboxes or Transmissions: The higher
torque capability combined with the high inertia rotor offers the opportunity
to eliminate expensive gearboxes that add weight, cost and gear backlash
to the servo installation. Lower power motors require gearboxes to obtain
the needed torque and lower speed control. ThinGap rotor inertia is
5-10 times higher than competitive servomotors with rotor mass approximately
85% of total motor mass. Eliminating the gearbox also offers the important
feature of both very slow and very high-speed load movements.
- Smoother Operation with Gearboxes: When gearboxes are required,
the extremely smooth incremental movement capability will drive gearboxes
to higher speeds with less gear wear from torque ripple.
- Back EMF Waveform, a Perfect Sine Wave: The more perfect the
EMF sine wave, the lower the harmonics, therefore providing a wider
range of speed without oscillations.
- Simplified Phase Tuning: Servo system engineers must phase
tune servomotors to the electronic driver, which is complicated by physical
differences in the three phase circuits of a brushless motor. The manufacturing
process of wire wound brushless stators typically results in electrical
differences between the three phases. The electronic driver must compensate
for these phase differences. The ThinGap coil design and manufacturing
precision is such that an insignificant 0.3% variation of phase resistance
is achieved. Servomotors are tested for motion overshoot and settling
times by examining the "S" Curve Profile. A finely tuned servomotor
follows the curve in forward and reverse movements. The ThinGap Servo-Motor
smoothly follows the motion curve with minimal overshoot and settling
time.
- Very Rapid Acceleration: A feature of the ThinGap Stator Coil
is the low electrical inductance characteristic. Low inductance means
fast response time and the ability to accelerate rapidly. This is a
definite advantage in high productivity factory automation such as pick-and-place
equipment. The value of quick movement relates directly to production
throughput. Robotic applications benefit from motors that are lightweight,
powerful, with good speed control and rapid acceleration ability.
THINGAP Motor Technologies
Ventura, CA
805-477-9741
www.thingap.com
email: info@thingap.com
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