Powerpoint presentation on Ultrasonic Motor

1. ULTRASONIC
PIEZOELECTRIC
MOTOR
RAKESH R
EEE-S7
46

2. MOTOR
• Device that converts electrical energy to
mechanical energy.
• ELECTROMAGNETIC MOTORS
 Current carrying conductor kept in a magnetic field
experiences a force or torque (Faraday’s law of EMI).
 Electrical energy Magnetic energy Mechanical
energy

3. Drawbacks of Electromagnetic Motors
• Noisy operation.
• Surge currents and spikes.
• Electromagnetic interference.
• Magnetic losses (Eddy currents & Hysteresis).
• High power consumption & high temperature.
• Low power factor.
• Comparatively lesser efficiency.

4. ULTRASONIC MOTOR (USM)
• A pressure applied across a pair of opposite
faces of a crystal, results in a PD developed
across the other pair.
PIEZOELECTRIC EFFECT
+ + + +
+ + + +
_ _ _ _
_ _ _ _
Mechanical
Pressure
Mechanical
Pressure
Potential
Difference

5. • When an AC is applied across a pair of
opposite faces, alternating compressions and
elongations (mechanical vibrations) are
obtained across the other pair of opposite
faces.
• As a result, a surface wave is formed over the
crystal driving force of the USM
Working Principle : CONVERSE PIEZOELECTRIC EFFECT

6. Construction
• ACTUATOR
 A piezoelectric material (Quartz, Barium Titanate,
Tourmaline, Rochelle Salt) is used as actuator.
 Actuator is fixed on the stator using thin metal
sheets and bearings.
 Actuator is directly connected to the supply
mains.
• STATOR
 Stator is made of any malleable material Steel.
 Ring, Cylindrical or Rod shaped.
Contd…

7. • ROTOR
 Same material as that of the stator.
 Same shape as that of the stator(Ring, Cylindrical
or Rod).
 Frictional coupling.
• CASING
 Cylindrical, Disc or Box shaped.
 Non- corrosive alloys or Fiber.
 To provide protection against abrasion & external
interferences.
Contd…

8. Working

9. Linear USM with double stators
Stator
StatorRotor
Actuator
Actuator

10. Coupling of Rotor & Stator
• Surface of contact b/w rotor & stator is made
uneven, so that they never slip off frictional
coupling.
• During motion, rotor is levitated from the
stator in the perpendicular direction less
wear & tear.
• Care is to be taken that friction doesn't cause
the interlocking of rotor & stator.

11. Types of USM
• Travelling Wave type
If the wave produced in the stator causes the particles
to experience both horizontal and vertical movement.
Produced by double actuators.
• Standing Wave type
If the wave produced in the stator causes the particles
to experience only vertical movement.
Single actuator is required.
NB: Both these types of USMs has got the same construction and working
principles, however the Travelling Wave type USMs are found to have better
operating characteristics.

12. Advantages & Disadvantages
Advantages
• High o/p torque & efficiency.
• High power to weight ratio.
• Good positioning accuracy.
• Capable of working in
extreme environmental
conditions.
• No magnetic interference.
• Simple construction.
• Small size, light weight, less
noise.
Disadvantages
• Requires high frequency
power supply(kHz range).
• Piezoelectric material is
expensive.
• Ultrasonic noise occurs.
• Drooping torque-speed
characteristics.

13. Applications
• Auto focusing & optical zooming in digital
cameras & surveillance cameras.
• Wrist watches & Clocks.
• Power steering, Power windows, Tilt steering,
ORVM, Car seat adjustment etc.
• Robotics.
• Aerospace.
• Medicine
• Hardware positioning (Hard disks, Floppy & CD
Drives) etc.

14. Conclusion
The above mentioned advantages and
applications, concludes the scope of
USMs in the day-to-day life.
However the disadvantages brings up the
need for further researches in the field.

15. Additional Info
• Piezoelectric effect was discovered by Jacques
Curie & Pierre Curie [France-1880].
• 1st Ultrasonic Motor was developed by V V
Lavrinenko [Russia-1965].

16. THE END