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 [email protected]
Jim Nimitz: Sales Engineer [email protected]
Tech Support: 408-919-0200
Questions?
Design WorldMiles [email protected]: 440.234.4531Twitter: @DW_Motion
Lin EngineeringTom [email protected]: 408.919.0200 ext. 457
Lin EngineeringJim [email protected]: 408.919.0200 ext. 233
Thank You This webinar will be available at designworldonline.com
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