NEWS

EVENTS AGENDA

45BLW18

BLDC flat motors are the ideal solution for many applications due to their compact, flat design (45mm diameter; length <30 mm). In the new 45BLW motors (16 poles design), the permanent magnets are located on the external rotor which rotate around the internal stator with the windings. In addition to the shorter design, the advantage of this construction compared to internal rotor motors comes from having the same output with lower torque ripple due to the rotor‘s higher moment of inertia.

The Assembly Show 2018

The Assembly Show 2018

Booth 1509

Donald E. Stephens Convention Center

Rosemont, Illinois

October 23-25, 2018

45BLW21

glossary

Acceleration

The time rate of change in velocity. Torque developed between the rotor and stator will cause the rotor to accelerate. The inertia of the rotor, and load, if any, will resist the applied torque and thus control the rate of acceleration.

Back EMF

The voltage produced across a winding due to its interaction with the rotating magnetic field generated by the motion of the rotor. Back EMF is proportional to the velocity of the rotor and in opposition to the voltage applied to the winding by the motor drive.

Bifilar Winding

A set of electrically connected coils in which two wires are simultaneously wound together around the stator.

Bipolar Driver

A driver capable of generating current flow through a winding in both directions.

Center Tap / Common Wire

The lead wire that connects the two wires in a bifilar winding. When a motor is operated in the unipolar winding configuration current enters each winding through the center tap, generally designated as A com or B com.

Closed Loop Control

A system of control in which the output or some result of the output is measured. This information is compared to the input to verify
command execution and make adjustments, if necessary.

Constant Current Driver / Chopper Driver / PWM Driver

A driver capable of adjusting the applied voltage across a winding to force and maintain rated current. A voltage is applied until the winding current reaches a pre-determined value. The supply is then switched off and it remains off until the current decays to a second lower pre-determined value. At that time the voltage is re-applied.

Constant Voltage Driver / L/R Driver / Resistance Limited (RL) Driver

A driver which maintains a constant applied voltage across each energized winding. The flow of current is limited only by the resistance/impedance of each winding.

Controller / Indexer / Pulse Generator

A device or circuit that generates a DC pulse train which is sent to the step motor drive. The number and rate of pulses generated determine the number and rate of steps the motor will ultimately execute.

Damping

The suppression of oscillations at the end of motion or during motion.

Detent Torque

The torque required to rotate a non-energized step motor.

Driver / Drive

An electrical device that drives a step motor based on pulses from a controller / indexer / pulse generator. A driver translates the pulse train and energizes the appropriate step motor windings.

Efficiency

The ratio of power output to power input.

Electrical Time Constant

The time required for a motor’s windings to charge to 63% of their rated current value.

Electromotive Force / EMF

A synonym for voltage, generally used to describe generated voltage.

Electronic Damping

The suppression of vibration by altering the flow of current to or the step rate
of a motor.

Encoder

A feedback device which can be used to derive positional and velocity information.

End Play

The axial shaft displacement due to an axial force.

End Taps

The lead wires that terminate (end) a phase/winding.

Energize / Excite

To send current through a phase or phases of a step motor

Feedback

The output or result of the output that is measured and sent back to the controller for comparison with the input during closed loop control.

Full Step Angle

The size of an incremental move made by a step motor determined solely by the motor’s construction.

Full Stepping

A method of driving a step motor in which each incremental movement is equal to the motor’s full step angle.

Half Stepping

A method of driving a step motor in which its full step angle is electrically halved by alternating between energizing one or two of the motor’s phases.

Half Stepping (Modified)

A method of half stepping in which the amount of current delivered to each phase is varied, depending on the number of phases
energized, to generate uniform torque throughout the entire step sequence.

Holding Torque / Static Torque

The maximum external torque that can be applied to an energized step motor at 0 pps without causing rotation.

Hybrid Step Motor

A step motor constructed using a permanent magnet rotor and whose rotor and stator assemblies are both made with tooth-like projections.

Inductance

The property of a winding that resists changes in current flow. Inductance is proportional to the square of the number of coil turns in each winding. The effects of inductance are especially noticeable at higher speeds.

Inertia

A physical property of matter that resists changes in speed or direction. Inertia of load affects the amount of torque required to accelerate and decelerate.

Inertia (Reflected)

The apparent inertia value transmitted to a step motor through a gear train.
The apparent value is the actual inertial value divided by the square of the gear ratio.

Mechanical Damper

A vibration reducing
device which is physically attached to a step motor.

Microstepping

A method of driving a step motor in which the full step angle of a motor is reduced electrically by separately controlling the amount of current to each motor phase.

Non-Cumulative Error

Error that does not add or accumulate over multiple steps or incremental movements.

Open Loop Control

A system of control in which the motor operates without feedback.

Overshoot

Rotation of a motor beyond its commanded position.

Permanent Magnet Step Motor

a.k.a. “PM” or
“Tin Can,” a step motor constructed using a permanent magnet rotor and whose rotor and stator assemblies
are both smooth.

Phase / Winding

A group of electrically connected coils.

Pole Pitch

The angle between adjacent poles of the same polarity on the rotor of a PM motor. The pole pitch determines the full step angle of a PM motor.

Poles

Areas of a motor where a magnetic pole is generated either by a permanent magnet or by passing current through the coils of a winding.

Pull-in Torque Curve

A graph showing the maximum torque, for a given speed, where a load can be accelerated into synchronism from a standstill.

Pull-out Torque Curve

A graph showing the maximum torque that can be applied to a step motor operating at a given speed without losing synchronism.

Pulse

An electrical signal or voltage of short duration.

Pulse Rate

Rate that successive pulses are sent or steps are initiated.

Radial Play

Displacement perpendicular to the shaft due to a force applied perpendicularly to the shaft axis.

Ramping

Increasing (or decreasing) the step rate of a motor gradually to prevent loss of synchronism.

Rated Current

The maximum allowable continuous current the motor can handle without exceeding its temperature rating at ambient temperature (usually
25ºC). It is the current at which rated holding torque has been determined.

Rated Voltage (Volts)

The voltage at which rated torque is generated with the motor at ambient temperature. Its value is the product of rated current and winding resistance.

Repeatability

The ability to return to a previously held position.

Resolution

The amount of rotation or linear motion produced when a motor executes a single step.

Resonance

A phenomena where excessive vibration occurs due to the motor operating at a frequency at or near the natural frequency of the entire system.

Resonant Range

The range where a motor’s step rate is near the natural frequency of the motor. A motor operating in this range may experience excessive vibration.

Rotor

The rotating part of the motor
(including magnets).

Slew Range

The region between the pull-in and pull-out torque curves. A motor may operate in this range, but cannot start, stop or reverse without ramping.

Stator

The stationary part of the motor, (including windings).

Step

The movement of the rotor from one energized position to the next.

Step (Stepping, Stepper) Motor

An actuator that translates discrete input pulses into motion composed of discrete incremental movements.

Step Accuracy

A measure of a step motor’s maxi- mum deviation from its desired or indicated position, calculated as a percentage of the step angle. This deviation is non-cumulative, meaning that the deviation found in any number of steps is no greater than the maximum deviation found in a single step.

Step Angle

The nominal angle through which the shaft of a step motor turns between adjacent step posi- tions. It is dependent upon the motor and driver sequence (full, half or microstepping).

Step Rate

The rate in steps per second at which a step motor is commanded to operate.

Step Sequence

The pattern in which a step motor’s phases are energized to generate motion.

Switching

Turning on and off voltage/current to a motors winding.

Synchronism

The condition in which a rotor’s rotation matches the rotation of the magnetic field created by the stator’s windings. In synchronism the motor’s step rate equals the controller’s input pulse rate. When synchronism is lost, the motor will stall or misstep.

HYBRID STEPPER

BRUSHLESS MOTOR

PM STEPPING MOTOR

AC SERVO MOTOR

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