Stepper Motors: Inside and Out

This webinar will be available afterwards at designworldonline.com & email

Q&A at the end of the presentation

Hashtag for this webinar: #DWwebinar

Before We Start

Moderator

Miles BudimirDesign World

Presenters

Jim NimitzLin Engineering

Tom LeLin Engineering

Stepper Motors: Inside and OutCommon Applications, Issues and Solutions

Presented by: Tom Le & Jim NimitzLin Engineering

Lin Engineering

• Started in 1987 as a consulting firm

• Founded by Ted Lin• Provides innovative

solutions to motion applications

• Manufacturing in Morgan Hill, CA and Nanjing, China

Industries & Applications

What We Will Discuss:1. Automation2. Medical 3. Aerospace and

Defense

Automation

What We Will Discuss:1. Common

Applications2. Insufficient Torque3. Optimizing Torque

Automation• As the Automation Industry expands, it

becomes more dependent on stepper motors

• Optimizing Torque and Smooth Motion from stepper motors is critical

• Common Applications Include:o Semiconductor Linear Stageso X – Y Table (2 Axis Movement)o 3D Printerso Cutting Machinery

AutomationSemiconductor Linear Stages:

AutomationCutting Machinery:

Automation – Linear Stages

• Used to give loads linear motion• Can be used in a horizontal or

vertical axis• Stepper motors must provide

smooth motion and high positional accuracy

• Higher operating speeds require steppers to maintain torque output

Insufficient Torque

• Magnetic Interaction between Coils and the Rotor

• Dynamic Torque decreases as Speed increases

Torque- Rotational Force

Insufficient Torque

• Larger motors generate more torque

• Greater Rotor Inertia and magnetic interaction

• Many applications are limited to a size constraint

Torque Case Study

Could Not Generate Enough Dynamic Torque at Desired Operating Speed

Customer’s Problem:

Optimizing Torque

Customized Motor Windings• Customized Windings for

Optimized Performance• Can Change Wire Gauge

and Turns per Coil to Tailor Motor Performance

Optimizing Torque

• Higher Inductance Lowers Dynamic Torque at Higher RPM

• Higher Inductance at Higher Speed Doesn’t Allow Current to Reach Rated Value

Optimizing Torque

Power In vs. Power Out• Can Optimize the

Winding for the Highest Motor Efficiency

Solution : Torque Case Study

By Optimizing the Winding, the Motor can Generate the Required Torque at the Desired Operating Speed

Proposed Solution:

Optimizing Torque

Gearbox and Pulley Assembly• Gearboxes and Pulleys

can be used to Produce more Torque

Medical

What We Will Discuss:1. Common

Applications2. Resonance3. Reducing Resonance

• Medical Devices require smooth motion and reliability from steppers.

• Therefore the motors must run accurately without interference.

• Common Applications Include:o Respiratorso Prescription Dispenserso Blood Analysis Machinery

Medical Industry

Medical IndustryPrescription Dispensers:

Medical IndustryAnalysis Machinery:

Medical – Respiratory Machinery

• Medical Device used to Remove Mucus from patient airways

• Requires high holding torque, accurate positioning, and position feedback

• Cannot overstep or miss steps

Resonance

When the frequency of a system’s oscillations matches the natural frequency

of the system.

Electrical Resonance

Stepper Motor Resonance:- At certain frequencies, the energy is

transferred to the motor body.- Natural step response is oscillatory

Resonance

• Every stepper system has unique resonance points

• Resonance can cause the system to: jitter, skip steps, lose accuracy, and even stall out.

• The system resonance leads to a loss of motor torque at defined motor frequencies; see the torque v. speed curve

Reducing Resonance

• Microstepping – Oscillations per step decrease greatly as steps become finer.

• Current: The motor can be overpowering. Many low speed applications will run smoother with reduced current (i.e. Lower the dT/dθ, torque stiffness)

Reducing Resonance

R-Winding• Created to reduce noise

and vibration for lower-torque applications

• Designed to eliminate the one-phase on position

Reducing Resonance

Mechanical Damping• Inertia Damping • Friction Damping,

Flange-mount damper

Electrical Damping• Driver Settings,

Microstepping• Special Windings

Reducing Resonance

Inertia Damper• Contains an inertia

body and elastomeric material

• Counters the effects of inertia

• Suppresses vibration

Aerospace and Defense

What We Will Discuss:1. Common Applications2. Environmental

Contamination3. High and Low

Temperatures

• Require rugged, long lasting and high performance motors that can withstand harsh environments

• Lin Engineering provided motors used in the B-2 Stealth Bomber

• Exampleso Satelliteso Ground Vehicleso Targeting Systemo Aircraft Ventilation

Aerospace and Defense

Heat Generation

Copper Loss:• Interaction between

current and resistance of the winding creates heat

Iron Loss:• Related to the

magnetic field interactions

High & Low Temperature

• Standard Motors (Class B)

• Temperature Classes

°C °FA 105 221B 130 266F 155 311H 180 356

Temperature Tolerance Class

Maximum Operation Temperature Allowed

High & Low Temperature

High Temperature• Bearing Grease, Teflon Leads,

Class H/F Insulator and Magnet Wires, Special Magnets

Low Temperature• Bearing Grease• Teflon Leads

Environmental Protection

IP Rating ( IP XX) • Protects Motor

Against Solid Objects and Liquids

Environmental Contamination

• Motors subject to rain need protection from liquid or solid ingress

• Moisture in between the rotor and stator can lead to rust

• Particles within the air gap can cause the motor to lock up

Wash Down Applications

Environmental Protection

IP 65• Protected Against Dust,

Low Pressure Jets of Water 

• Better Protection from Environmental Elements 

Environmental Protection

IP X7•  Protected Against Dust;

Submersible in Depths of 15cm to 1m 

• Better Protection from Damaging Environmental Elements

Aerospace and Defense – Aircraft

Ventilation

• Steppers require protection from the environment (i.e. rain, moisture, pressure)

• Must operate in extreme temperatures; high and low

Environmental Protection•  

Thank You!

Tom Le: Applications Engineertle@linengineering.com

Jim Nimitz: Sales Engineer jnimitz@linengineering.com

Tech Support: 408-919-0200

Questions?

Design WorldMiles Budimirmbudimir@wtwhmedia.comPhone: 440.234.4531Twitter: @DW_Motion

Lin EngineeringTom Letle@linengineering.comPhone: 408.919.0200 ext. 457

Lin EngineeringJim Nimitzjnimitz@linengineering.comPhone: 408.919.0200 ext. 233

Thank You This webinar will be available at designworldonline.com

& email

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