Servo Motors

Servo Motors

Servo Motors

Servo motors are often used as a high-performance alternative to a stepper motor. Stepper motors, by comparison, have an inherent ability to control position as their motion is based on output steps from a step & direction signal. This allows the stepper motor to be used in open-loop position control applications without any feedback device since the signal from their stepper drive specifies the number of steps & direction to rotate per shaft revolution. However, the lack of position feedback limits their performance since the stepper motor can only drive a load that is well within its torque capacity.  Missed steps under load usually lead to positioning errors or a stall condition when no closed-loop feedback is in place. Additionally, load–to-motor inertia matching is absolutely critical when using a stepper motor, but less so when using a servo motor.

Servo Motor Types

Servo motors come in two main types: brush and brushless. Both servo motor types operate in a continuous torque range as well as a peak torque range. Peak torque can be much higher than continuous torque, but can only be achieved for short periods of time. By comparison, continuous torque can be reached throughout the regular operation of a servo motor.

The brush type motor is an older technology that can be run with simple motor controls, such as 2 or 4 quadrant servo drives, but have parts (graphic or precision metal brushes) that require maintenance. Todays preferred servo motor is brushless. The brushless servo motor has no component maintenance but does require a servo drive that can electronically commutate the motor. This is normally done with a primary feedback device like Halls Sensors. A brushless servo motor will normally have an encoder or resolver for accurate position feedback that can be used used to control both position and/or velocity.

Brushless servo motors can be rotary, linear or frameless in construction. They can perform very simple motion or be used in highly dynamic requirements. Applications include: robotics, CNC machinery, laser cutting, packaging, printing, material handling and many other automated manufacturing processes.

DC Motor/Brushed MotorsView More

DC Brushed Motors that have winding in the rotor and permanent magnets on the stator. Carbon brushes and a mechanical commutator provide a current path through the windings to achieve motor torque. A DC motor will continuously rotate if a DC power source is applied across its terminals. DC motors require simpler drives but require higher maintenance, and are larger in size for the same output power.

There are two types of brushed permanent magnet DC motors: iron core and moving coil rotor.

Moving Coil Rotor Motors feature:

  • High acceleration due to a low mass inertia
  • Low electromagnetic interference
  • Low inductance
  • High efficiency
  • Linearity between voltage/load & speed, and load & current
  • Small torque ripple

Iron Core Rotor Motors feature:

  • High torque-to-inertia ratio
  • High starting torque
  • Low thermal resistance
  • Low current consumption
  • High inertia for improved load-to-motor inertia matching
  • Low cost

Brushless Servo MotorsView More

Brushless Servo Motors that have windings in the stator and permanent magnets attached to the rotor. No brushes are used. Motor rotation is achieved by means of electrical commutation performed by the drive. Brushless servo motors provide high acceleration, high torque, and no maintenance. Brushless Servo Motors offer the highest torque-to-weight ratio and are commonly used in the highest throughput, precision and demanding applications.

There are two types of brushless servo motors:

Slotted Motors feature:

  • Better accel/decel capabilities
  • Better load to rotor inertia ratio
  • Lower rotor inertia
  • Lower cost vs. slotless motors

Drawbacks of slotted motors include: cogging, high speed operation and lower efficiency vs. slotless design.

Slotless (coreless) Motors feature:

  • Zero cogging
  • Smooth operation
  • Increased heat dissipation
  • Ability to withstand high peak torque
  • High power density
  • Lowest electrical time constant
  • Low inductance

Drawbacks of slotless motors include: low inductance, low moment of inertia, cost and lower accel/decel capabilities vs. slotted design.

Linear Servo MotorsView More

A linear motor provides direct linear motion (rather than rotary). Electromagnetic force is utilized to produce thrust directly, eliminating the need for rotary to linear conversion. Advantages include: high speeds, high precision, fast response, stiffness, zero backlash and maintenance free operation. Disadvantages include: higher cost, required higher bandwidth, larger footprint and heat. Types: Iron core, air core, and slotless.

Pancake Servo MotorsView More

Available in both Brush and Brushless varieties, these flat disc armature motors feature:

  • Low inertia
  • Low axial profile
  • High-pulse torque capability
  • No cogging even at low operating speeds

Drawbacks of pancake servo motors include: cost, delivery, customization, low inductance and low inertia.

Direct Drive Rotary MotorsView More

Direct Drive Rotary Motors are brushless motors with high resolution encoders or resolvers, plus optional radial bearings that turn the table top or integral coupling which is directly attached to the load. Key benefits include high accuracy and torque in a package that does not have a gear reducer.

The key disadvantages include high system cost, larger size, and the requirement of using a specific motor control system, one designed for that specific rotary motor.

Search our Servo Motor Products by subcategory at the links below:

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  1. C041A (240 VAC) Frameless Motors Kollmorgen
    C041A (240 VAC)

    108mm Frame Size, 4.57 Nm Max Cont. Torque, 1750 RPM Max Speed

  2. C041B (240 VAC) Frameless Motors Kollmorgen
    C041B (240 VAC)

    108mm Frame Size, 4.52 Nm Max Cont. Torque, 2500 RPM Max Speed

  3. C042A (240 VAC) Frameless Motors Kollmorgen
    C042A (240 VAC)

    108mm Frame Size, 8.25 Nm Max Cont. Torque, 1700 RPM Max Speed

  4. C042B (240 VAC) Frameless Motors Kollmorgen
    C042B (240 VAC)

    108mm Frame Size, 8.45 Nm Max Cont. Torque,2500 RPM Max Speed

  5. C043A (240 VAC) Frameless Motors Kollmorgen
    C043A (240 VAC)

    108mm Frame Size, 11.1 Nm Max Cont. Torque, 1250 RPM Max Speed

  6. C043B (240 VAC) Frameless Motors Kollmorgen
    C043B (240 VAC)

    108mm Frame Size, 11.2 Nm Max Cont. Torque, 2500 RPM Max Speed

  7. C044A (240 VAC) Frameless Motors Kollmorgen
    C044A (240 VAC)

    108mm Frame Size, 13.9 Nm Max Cont. Torque, 1050 RPM Max Speed

  8. C044B (240 VAC) Frameless Motors Kollmorgen
    C044B (240 VAC)

    108mm Frame Size, 14.4 Nm Max Cont. Torque, 2150 RPM Max Speed

  9. C051A (240 VAC) Frameless Motors Kollmorgen
    C051A (240 VAC)

    138mm Frame Size, 11.7 Nm Max Cont. Torque, 1200 RPM Max Speed

  10. C051B (240 VAC) Frameless Motors Kollmorgen
    C051B (240 VAC)

    138mm Frame Size, 11.9 Nm Max Cont. Torque, 2450 RPM Max Speed

  11. C052C (240 VAC) Frameless Motors Kollmorgen
    C052C (240 VAC)

    138mm Frame Size, 16.9 Nm Max Cont. Torque, 950 RPM Max Speed

  12. C052D (240 VAC) Frameless Motors Kollmorgen
    C052D (240 VAC)

    138mm Frame Size, 16.5 Nm Max Cont. Torque, 2050 RPM Max Speed

  13. C053A (240 VAC) Frameless Motors Kollmorgen
    C053A (240 VAC)

    138mm Frame Size, 21 Nm Max Cont. Torque, 1350 RPM Max Speed

  14. C053B (240 VAC) Frameless Motors Kollmorgen
    C053B (240 VAC)

    138mm Frame Size, 20.2 Nm Max Cont. Torque, 2500 RPM Max Speed

  15. C054A (240 VAC) Frameless Motors Kollmorgen
    C054A (240 VAC)

    138mm Frame Size, 24.9 Nm Max Cont. Torque, 1200 RPM Max Speed

  16. C054B (240 VAC) Frameless Motors Kollmorgen
    C054B (240 VAC)

    138mm Frame Size, 23.8 Nm Max Cont. Torque, 2350 RPM Max Speed

  17. C061A (240 VAC) Frameless Motors Kollmorgen
    C061A (240 VAC)

    188mm Frame Size, 33.8 Nm Max Cont. Torque, 900 RPM Max Speed

  18. C061B (240 VAC) Frameless Motors Kollmorgen
    C061B (240 VAC)

    188mm Frame Size, 32.6 Nm Max Cont. Torque, 1950 RPM Max Speed

  19. C062B (240 VAC) Frameless Motors Kollmorgen
    C062B (240 VAC)

    188mm Frame Size, 44.6 Nm Max Cont. Torque, 1400 RPM Max Speed

  20. C062C (240 VAC) Frameless Motors Kollmorgen
    C062C (240 VAC)

    188mm Frame Size, 48.4 Nm Max Cont. Torque, 700 RPM Max Speed

  21. C063B (240 VAC) Frameless Motors Kollmorgen
    C063B (240 VAC)

    188mm Frame Size, 59 Nm Max Cont. Torque, 1050 RPM Max Speed

  22. C063C (240 VAC) Frameless Motors Kollmorgen
    C063C (240 VAC)

    188mm Frame Size, 61.8 Nm Max Cont. Torque, 550 RPM Max Speed

  23. C091A (240 VAC) Frameless Motors Kollmorgen
    C091A (240 VAC)

    246mm Frame Size, 50.2 Nm Max Cont. Torque, 600 RPM Max Speed

  24. C092C (240 VAC) Frameless Motors Kollmorgen
    C092C (240 VAC)

    246mm Frame Size, 102 Nm Max Cont. Torque, 450 RPM Max Speed

  25. C093C (240 VAC) Frameless Motors Kollmorgen
    C093C (240 VAC)

    246mm Frame Size, 139 Nm Max Cont. Torque, 350 RPM Max Speed

  26. C131B (240 VAC) Frameless Motors Kollmorgen
    C131B (240 VAC)

    351mm Frame Size, 190 Nm Max Cont. Torque, 450 RPM Max Speed

  27. C131C (240 VAC) Frameless Motors Kollmorgen
    C131C (240 VAC)

    351mm Frame Size, 189 Nm Max Cont. Torque, 250 RPM Max Speed

  28. C132B (240 VAC) Frameless Motors Kollmorgen
    C132B (240 VAC)

    351mm Frame Size, 361 Nm Max Cont. Torque, 225 RPM Max Speed

  29. C132C (240 VAC) Frameless Motors Kollmorgen
    C132C (240 VAC)

    351mm Frame Size, 362 Nm Max Cont. Torque, 120 RPM Max Speed

  30. C133B (240 VAC) Frameless Motors Kollmorgen
    C133B (240 VAC)

    351mm Frame Size, 510 Nm Max Cont. Torque, 175 RPM Max Speed

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