Precision Sub-Fractional Motor Technologies: - PowerPoint Presentation

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Uploaded On 2018-03-08

Precision Sub-Fractional Motor Technologies: - PPT Presentation

How to Match the Best Technology for Your Application Day 2 DC Brush PM amp Piezo Motors AdvantagesDisadvantages Examining Selected Precision Application Examples for SubFractional Motors ID: 642717

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Slide1

Precision Sub-Fractional Motor Technologies: How to Match the Best Technology for Your Application

Day 2: DC (Brush) PM &

Piezo

Motors, Advantages/Disadvantages, Examining Selected Precision Application Examples for Sub-Fractional MotorsSlide2

Motor Technology in Precision Applications Using Small Motors

Day

Brushless PMDay 2- Brush DC PMDay 3- Stepper (focus on PM)

You are hereSlide3

Brush DC PM Technology Review OutlineIntroduction

History: Concept to Commercialization

Motor Technology Advantages

Motor Technology Disadvantages Expected Enhancements, Changes, etc.Suppliers of Note Application List and/or ExamplesSlide4

History: Concept to CommercializationSlide5

The First DC MotorBuilt by Thomas Davenport in his shop in Vermont in 1837.

He used magnetized railroad track spikes secured to a wooden drum for the rotor.

He purchased an electromagnet for the stator winding.

His wife sacrificed a silk dress for the wire insulation.The electric source was a 3 cell Grove battery.The invention was a technical success but a dismal commercial failure.Slide6

Brush DC motors have evolved into high-performance energy converters with the advent of permanent magnets.Slide7

Evolution of PM Brush DC Motors and Piezo Actuators

1950s – Alnico Torque Motor

Invention of the self-supporting motor coil, without need for an iron core (

slotless) by Dr. Faulhaber1960s – Ceramic Motor and Tachometer1970s – Rare Earth Motor (SaCo)1980s – Rare Earth Motor (NeoFe)1990s – Bonded Rare Earth Motors in Higher Volume Applications2000s- First piezo actuator developed by PiezoMotor

AB, supported by

Faulhaber

and later in the decade introduced to MICROMO customersSlide8

Brush DC PM Basics: Advantages and DisadvantagesSlide9

Brush DC PM AdvantagesSlide10

Getting a motor moving requires the proper timing of current in the motor windings. This function is called “motor commutation.”The simplest commutation system is a mechanical one in the form of a metal ring electrically divided in segments, where each segment is connected to part of the motor windings.

As the commutator ring and windings rotate together, the timing of the current in the windings depends on which “commutator” segments are in contact with the metal brushes.

Brush DC PM AdvantagesSlide11

Brush DC PM Commutation: Simple, Inexpensive

to winding

current

Brush Is

stationary

Commutator

and Windings

Rotate Together

DC Volts

DC VoltsSlide12

Simple linear relationship between voltage and speed. Easy to control.Low cost approach to variable speed drives and positioning.Well down the manufacturing cost curve.

Brush DC PM AdvantagesSlide13

Brush Motor Cross-section

Drive, Control

Circuitry

BrushRotatingWindings

Stationary

MagnetsSlide14

Next two slides show relative simplicity of Brush control compared to Brushless DC motor control<Toggle back and forth to illustrate>Slide15

Brushless DC PM Motor, Drive, Feedback Connections

Rotating

Magnets

Sponsored by:Slide46

Precision Applications Using S

mall

otorsSlide47

Remote Presence Robot

Challenge?

Need expertise located remotely with a patient in immediate need? Need remote control to move about, see, hear, and be seen and be heard? Need to be able to operate on batteries; quiet; reliable?

Motor Need?Highly reliable, efficient, lighter weight, small, higher power per volume.Motion Solution?Coreless brush motor, geared (planetary, low backlash, precise) to translate higher speed to higher torque. Electronics for precision camera positioning; mitigation of EMI/RFI emissions. Innovative feedback combining potentiometers and magnetic encoders to achieve absolute and relative positioning inexpensively. Slide48

Autonomous All Terrain Vehicle

Challenge?

How do you go where it may be unsafe or difficult for humans to assess a problem; rescue miners or earthquake victims; inspect or analyze farm land; inspect nuclear plants; inspect construction in progress or hazardous industrial areas? All in extremely varied and at times difficult terrain?

Motor Need?Operate at very low voltages (battery, solar powered); high torque per weight; easy to control.Motion Solution?Coreless brush motor, geared (planetary, low backlash, precise) with precious metal commutator for minimum size and ability to operate at lower voltages. Small and light weight are also important in mobile applications.Slide49

Rosetta C

omet Exploring Space Probe

Challenge?

Ever land on a comet orbiting the Sun for exploration? No one has! So…you need to be ready for almost any situation with motorized sub-systems for controlled landing, anchoring, orienting the landing probe.Motor Need?Reliability of the highest order; simple controls; space ready. Small, lightweight. High torque per volume.Motion Solution?14 brush DC motors and controls, geared (planetary, low backlash, precise)

to translate higher speed to higher

torque. Motor functions include: precision camera positioning to search for good landing site; act as motors and generators to capture precious power from kinetic motion; draw anchor lines taught; actuating analytical instruments.

Landing Probe

Anchoring

ActuatorSlide50

Piezo Actuators Overview

Piezo

technology, while not electromagnetic in nature, is an interesting and alternative approach to actuation where physical contact (like brushes in a DC PM motor) help convey the energy needed for motion.

Like a DC motor, piezo technology is energized by applying a voltage to the mechanism and that electrical energy is converted to mechanical energy in the form of vibrations.By controlling the application of the energy and the structure of the stationary and moving elements, linear or rotary motion is initiated. Many camera auto-focuses use piezo rotating motors. Metrology applications (small movements) are also an important area of use.Slide51

Piezo Advantages/Disadvantages

Advantages:

Capable of very small moves (

nano motion).Very high holding torque with almost no power consumed.Fast response (micro-seconds) compared to electromagnetic devices (high milli-seconds).Operate in harsh environments such as vacuums, extreme cold, high magnetic fields, high energy radiation where typical electro-magnetic and PM actuators require special designs or materials.Disadvantages (compared to electromagnetic devices)Operate primarily at very slow speeds.Travel is limited.Limited at high temperature levels (200 deg C).Made of brittle material.High hysteresis (does not return to original position) and creep, but both controllable.Slide52

Surgical Robot I

nside

n MRIChallenge?If you can position a surgical probe remotely, while you view an active MRI image you can increase the accuracy of the surgical procedure and reduce surgery time. But the extremely strong magnetic field of the MRI creates significant challenges for standard electric motor-driven robots. Screws, gears,motors become hazards within the MRI unit. Motor Need?Unaffected by the strong magnetic field of the MRI machine. Accurate, micro positioning. Audibly and electrically quiet.

Motion Solution?

Piezo

-electric ceramic actuator. Creates motion

when a voltage is applied. No magnetic/metal parts.

Special design to increase speed. Inherently safe as loss of power brings

the motion to a stop.