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.