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motortechnology
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motorCOMPASS
Wondering which type of miniature motor would work best? Learn more about the characteristics and advantages of the different motor technologies. |
Brushless DC Motors
| Brushless DC |
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Details |
Characteristics |
Advantages |
| Permanent Magnet DC Design |
Essentially linear torque/speed curve, with torque proportional to current and speed proportional to voltage |
Ease of speed and position control |
| Brushless Design |
Life is not limited by brush wear but only by wear in ball bearings |
Very long life, high reliability, insensitive to environment. No arcing, dust free. Reduced audible and electrical noise |
| Static winding attached to motor housing |
Improved heat dissipation |
Overload capability
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| Slotless Configuration |
No detent torque |
Excellent velocity smoothness |
| Versions without hall sensor |
Typically used in spindle applications |
Cost effective. Less sensitive to environment. Only three connecting wires. |
| Versions with hall sensors |
Typically used in applications where speed or load variation are needed |
Very simple commutation circuitry |
| Versions with encoder or resolver |
Typically used in incremental motion |
Very precise speed and position control |
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Brush DC Motors
| Brush DC |
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Details |
Characteristics |
Advantages |
| Ironless Rotor |
Low moment of inertia |
High acceleration. Ideal for incremental motion; Linear speed-torque function. Insensitive to shocks |
| No hysteresis and eddy current losses |
High efficiency, low losses from friction only. Ideal for battery operation |
| No magnetic saturation |
High peak torques without the risk of demagnetization |
| Central Stator Magnet |
High power per size and per weight |
Ideal for portable or small equipment or requiring small dimensions |
| Small Sized Bearings |
Low viscous damping |
High peak speeds, very low speed dependent losses, low starting voltage |
| Precious Metal Commutation System |
Low friction, little electrical noise |
Low losses and wear, low electromagnetic interference |
| Copper-graphic commutation |
High current densities may be commutated |
High continuous and peak torques without the risk of demagnetizing to motor. Very long life. Ideal for chopper drivers |
| Rated rotor temperature up to 155 degrees Celsius. |
Continuous torque is exceptionally high for the motor size, reducing the weight, dimensions and the cooling system |
| Very compact commutation system |
Excellence resistance to shocks and vibration |
| High torque to inertia ratio |
High acceleration, short mechanical time constant |
Stepper Disc Magnet Motors
| Stepper Disc Magnet |
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Details |
Characteristics |
Advantages |
| Thin mulitpolar rare earth disc magnet |
Very low rotor inertia |
Very high acceleration |
| Short iron circuit made of SiFe laminations; Coils placed near to the air gap |
Low iron losses |
High start/stop frequencies |
| More torque at high step rates |
High speeds |
| Independent magnetic circuit |
No coupling between phases |
High power/volume ratio |
| Simple magnetic circuit |
Sinusoidal torque function, low detent torque |
Superior angular resolution in microstep mode |
| Optimally designed magnetic circuit |
Torque constant is linear up to 2 to 3 times nominal current |
High peak torques |
| High energy magnet |
High power to weight ratio |
For motors in mobile applications |
Stepper Can Stack Motors
| Stepper Can Stack |
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Details |
Characteristics |
Advantages |
| Radially magnetized permanent magnet rotor |
High torque to size ratio |
Machine size reduction |
| Bobbin wound coil design |
Uniolar/Bipolar windings can be designed for optimum performance |
Tailoring to exact needs of application |
| Sintered bronze bearing design – Ball bearings option |
Long life lubrication |
Increased warranty on machine |
| Step angle variation – 3.6 degree to 20 degree |
Design capability for finer mechanical resolution |
Finger resolution required |
| Simple motor construction |
Simple mechanical construction with proven design characteristics |
Customization to meet application demands |
Stepper Hybrid Motors
Stepper Hybrid |
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Details |
Characteristics |
Advantages |
| Aluminum housing design |
Superior heat dissipation |
Increased duty cycle improves torque |
| Multi-toothed rotor and stator – step angles down to 0.9 degree |
Fine mechanical resolution |
Higher precision in application |
| Captured bearings |
Prevents bearing spinout |
Noise reduced during operation |
| Linear actuator axial play reduced to zero |
Linear axis eliminates slippage during operation |
| Stator enhanced magnets |
nUp to 40% more torque in same package |
Reduced size on each axis |
| Precision radial ball bearing design |
Mechanical and electrical modifications available |
Customization to meet application needs | |
Digital Linear Actuators
| Digital Linear Actuators |
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Details |
Characteristics |
Advantages |
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Can Stack design with threaded rotor and bobbin wound coil |
Windings can be designed for optimum performance |
Optimized per application requirements |
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Stub acme thread design |
Various linear step resolutions - .0005 to .0040 inch |
Fast, powerful and precise positioning |
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Simple motor construction |
Simple mechanical construction with provden design characteristics |
Customization to meet application demands; External components reduced in application |
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Captive and non-captive designs |
nOptions to conform to space requirements |
Machine size reduction |
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Precision radial ball bearing design |
High force to size ratio |
Customization to meet application demands |
Gearheads
| Gearhead |
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Details |
Characteristics |
Advantages |
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Spur gear concept: Only 1 transmission point per train |
Low friction per train. Arrangement of several trains as intended by the designer. Input and output shaft not necessarily in line. Two output shafts possible. |
Good efficiency, about 0.9 per train. Long gearbox of smaller diameter or short gearbox of large diameter. Free choice for placing the motor relative to the output shaft. Mounting of a sensor, a potentiometer etc. |
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Input wheel made of special grade plastics |
Reaction of mechanical noise generated at high motor speeds |
Silent functioning |
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Planetary concept: 3 or 4 transmission points per train |
Reduction ratio per train is higher but so is friction. Can transmit higher torques. Input and output of a train have the same direction of rotation. Less backlash. |
Less trains for a given reduction ratio efficiency about 0.85 per train. Very compact gearbox for its performance. For any number of trains, the load always rotates in the same direction as the motor. Smaller shock in case of a rapid reversal of motor rotation. |
Encoders
| Encoder |
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Details |
Characteristics |
Advantages |
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DC tachometer: V (velocity sensor), ironless rotor, commutation system made of precious metals |
Delivers a continuous signal, adds neglectable inertia, constant signal quality |
Easy control even at very low speeds, little additional load for the motor, Low sensitivity to hostile environements |
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Magnetic encoder: P (position sensor), encoder integrated in the motor, position monitored by hall sensors |
Simple construction, compact design, two output channels |
Insensitive to hostile environments, negligible increase in length of the unit, very low current consumption, high reliability and long life |
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Optical encoder: P+V |
High resolution, two channels, plus home position, signal level very stable, cuts LED supply at stall, no thermal drift |
Very precise positioning, facilitates counting the number of revolutions, no phenomenon of aging, lower consumption and lower temperature rise, insensitive to temperatures, small dimensions |
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