Post on 07-Nov-2014
description
Dr. Adel Gastli
Electromechanical Systems & Actuators
LINEAR MOTORS
CONTENTIntroduction Types of Linear Motors Applications
Dr. Adel Gastli
Linear Motors
2
INTRODUCTION Linear Motors are old motors which date from the 1970s. Were not intensively used because of their difficult
control and low performance. Advancements in Power Electronics and Microprocessors have overcome the control difficulties and have revived the use of the linear motors. Linear motors are nowadays emerging as new technologies.
Dr. Adel Gastli
Linear Motors
3
Main Types of Linear Motors Linear Synchronous Motor Permanent Magnet Wound Secondary Type Linear Induction Motor Single-Sided: Long-primary & Short Secondary Short-primary & Long-Secondary Double-Sided or Sandwich Linear Stepper Motor
Dr. Adel Gastli
Linear Motors
4
Linear Synchronous Motor (LSM)Field Yoke Field winding
I
Passive rail truck
Armature winding
Dr. Adel Gastli
Linear Motors
5
LSM (Contd)For an LSM to operate properly the control system must accurately track the position of the moving element in order to properly synchronize the moving field current in the stationary frame (stator). If synchronization is lost or interrupted the motor slips and loss of propulsion can occur. This situation is likely to be encountered by an LSM when external sensors are relied upon to handle motor synchronization. If a sensor becomes dirty or mis-aligned or if fog, smoke or other airborne obstructions are present, the system will experience problems.Dr. Adel Gastli Linear Motors 6
LINEAR INDUCTION MOTOR (LIM)Linear Induction Motors (LIMs) are significantly different than Linear Synchronous Motors (LSMs) in the way that they produce electro-motive forces or motion. In a LIM, the motor stator creates an Alternating Current (AC) field that induces currents into the reaction plate, which is typically an aluminum fin. This creates eddy currents in the moving element which react with the moving field in the stator to produce thrust. The induced currents in the aluminum plate manifest themselves in the form of heat. In cases of high duty cycles or in locked rotor conditions (where the moving element is not permitted to move) overheating can occur. In several reported cases at amusement parks, LIM fins have cracked and parts have melted.
Dr. Adel Gastli
Linear Motors
7
LIM (Contd)Cut along xy and enrollx Stator 3 winding Secondary y Primary Rotor Aluminum sheet (conductor)Traveling mmf (or Flux Density) Wave
v vs
Dr. Adel Gastli
Linear Motors
8
Traveling mmf waveLINEAR INDUCTION MOTOR
FNi/2/20
Fundamental F1
/2
-Ni/2
zg
Fundamental H1
HNi/20 0
Ni/2g
Fundamental F1 F
F: mmf H: Field
/2
-Ni/2
/2
-Ni/2g
z
Dr. Adel Gastli
Linear Motors
9
Traveling mmf waveLINEAR INDUCTION MOTOR
Same Analogy as that of Rotary Machines
2z 3 ib = I m cos(t 120 ) F ( z , t ) = Fmax cos t 2 ib = I m cos(t + 120 ) ia = I m cos t Fmax =v=Dr. Adel Gastli
4
kw
N ph I m 2m
Nph : Number of turns distributed over a length m . kw : winding factor.
dz dz d = = = 2Tp f dt d dt 2Linear Motors
Tp : Pole pitch f : Exciting frequency.
10
LIM PerformanceLINEAR INDUCTION MOTOR Slip
s=
vs v vs
v s = 2 Tp f [m / sec]
Thrust
3 I'22 R '2 / s F= = [N] synchronous velocity, v s vs air gap power, PgR1 l1 M l2 R2/s
Thrust, F
vsDr. Adel Gastli Linear Motors
Speed, v 11
Different Types of LIMLINEAR INDUCTION MOTOR
DOUBLE-SIDED LIM (DLIM)Secondary Primary
SINGLE-SIDED LIM (SLIM)Short Primary Long Primary
Long Secondary
Short Secondary
Dr. Adel Gastli
Linear Motors
12
End EffectLINEAR INDUCTION MOTOR
There is secondary current and secondary loss which is not
associated with a corresponding amount of useful thrust. There are reactive volt-amperes drawn from the supply which cannot be accounted for either as being due to magnetization or leakage reactance. The physical nature of this phenomena is thought to be due to the continual removal of magnetic energy at the exit edge of a machine. The exit edge produces a backward thrust on the secondary which subtracts from the thrust performance in the region of a speed-thrust curve.Dr. Adel Gastli Linear Motors 13
End Effect on Speed-Thrust CurveLINEAR INDUCTION MOTOR
The LIM cannot run lightThrust, F
at the synchronous speed vs=2pf. Generally, the running light
Short-Primary LIM Equivalent Rotary IMvs
speed is lower than vs.
Speed, v
Effect of the exit edge loss on the speed-thrust curve of a LIM.
Dr. Adel Gastli
Linear Motors
14
APPLICATIONS Transportation (Trains) Robotics & Material Handling Elevators Compressors & Pumps Catapults and Launchers Sliding Doors Closer Cartain pullers etc...
Dr. Adel Gastli
Linear Motors
15
Transportation (Trains)
Japan: Linear Chuo ShinkansenDr. Adel Gastli Linear Motors 16
Superconducting Magnetically Levitated Linear Motor Car The superconducting Magnetically-levitated
Linear Motor Car is a most promising high speed transportation system in the 21st century. It is a vehicle befitting the requirements of the
high speed and massive transportation age, as it operates at a stunning 500 Kmph, and has the transportation capacity equivalent to the existing shinkansen. It is a most advanced traffic system, which has
less noise and vibration and promises a safe and comfortable ride.
Dr. Adel Gastli
Linear Motors
17
Train Depot
Tunnel
Control Center Turnout switches Test platform
Vehicle Via duct
Information cables
Feeding section switchgears Feeder Guideway Power conversion substation Dr. Adel Gastli Linear Motors Power converter 18
Panel-type Side wall
LCX (Leaky coaxial cable)
Levitation and guidance coils
Feeding cable
Propulsion coils
Cross-inductive cable
Power/ communication cables
Dr. Adel Gastli
Linear Motors
19
What is Superconductivity? When certain metals are cooled below a specific temperature, their
electric resistance vanishes. This phenomenon is known as "superconductivity". Once current is applied to a coil made of superconductive metal, it
continues to flow permanently and without loss. This coil can generate dozens of times stronger magnetic field than that of permanent magnets. For the Maglev, a bundle of extremely fine niobium-titanium alloy
(superconductive metal) wire is embedded in a copper matrix in order to improve the stability of superconductivity. This wire is cooled with liquid helium (ca-269C) to be in a superconductive state.
Dr. Adel Gastli
Linear Motors
20
How does it advance forwards? (Propulsion System) By passing current through propulsion coils on the ground,
a magnetic field (north and south poles) is produced, thus the train is propelled forward by the force of attraction between opposite poles and the repulsive force of same poles acting between the ground coils and the superconducting magnets built into the vehicles.
Dr. Adel Gastli
Linear Motors
21
How is it levitated ? (Levitation System) When the superconducting magnets on the vehicles pass
through at high speed current flows through levitation and guidance coils on the ground producing electrodynamic levitating force to the vehicles.
Dr. Adel Gastli
Linear Motors
22
Why doesn't it collide with the wall? (Guidance System) The levitation and guidance coils on either side are
connected with electric power cables. They keep the vehicles in the center of the guideway at all times by exerting an attractive force on the further side of the vehicle and a repulsive force on the nearer side should the train move off center to either side.
Dr. Adel Gastli
Linear Motors
23
Other Types of Levitation Systems
Dr. Adel Gastli
Linear Motors
24
One-shaft Multicar Ropeless ElevatorsMoving part of linear Synchronous motor Stationary armature coil of motor
Elevator car Elevator path
Elevator Car
Elevator Hall
Dr. Adel Gastli
Linear Motors
25
Decentralized Elevator Cars Group Control Means maximum operating time. Each elevator controller can act as the
group controller. If one controller is taken out of service
temporarily, the remaining controllers continue to operate efficiently.
Dr. Adel Gastli
Linear Motors
26
Permanent magnets Yoke Armature coils Suspension bar
Rollers
Magnet holder
Elevator car
Dr. Adel Gastli
Linear Motors
27
38-story tower of terror in Australia
38-story tower of terror in Australia
Ramp
A state-of-the-art linear motor system propels the ride to reach unprecedented speeds of up to 160 km/hour, making it the most technologically-advanced ride in the world. To generate these intense speeds, an incredible 2,200,000 watts (2.2 megawatts) of power, enough to power a small town, is applied for six or seven Linear Motors Dr. seconds. Adel Gastli 28
Linear CompressorA linear compressor is a positive displacement, piston-type compressor in which the piston is driven directly by a linear motor, rather than by a rotary motor coupled to a mechanical mechanism as in a conventional reciprocating compressor.
Dr. Adel Gastli
Linear Motors
29
Air Compressor and Vacuum Pumps Linear-motor-driven Free Piston SystemThis design makes these pumps especially appropriate as air sources or vacuum units for various pneumatically operated equipment and apparatus in advanced industries.
Dr. Adel Gastli
Linear Motors
30
Linear motor outperforms steam-piston catapults Replacement for naval-aircraft launch system offers host of
tactical and operational benefits. In the rural Massachusetts town, engineers are developing the world's highest-thrust linear motor. For Naval aviation, it may mean the end of the age of steam. By 2005, naval architects may begin replacing the enormous steam catapults on aircraft carriers with EMALS--The Electromagnetic Aircraft Launch System.
Dr. Adel Gastli
Linear Motors
31
Linear motor outperforms steam-piston catapults (Contd)EMALS would bring a host of improvements to ship design and Naval aviation. With a maximum design thrust of 132,000 kgf, EMALS offers 28% more thrust than steam catapults. Proposed EMALS could accelerate 45,000-kg aircraft to 60 m/s2 in 100m.
Dr. Adel Gastli
Linear Motors
32
The Launch Loop: a low cost Earth-to-high orbit launch systemLinear motor and deflecting magnet 80 km Loop
Maglev train riding on the loopA closed loop made of laminated iron ribbon is continuously launched to space by an asynchronous linear motor. The motor consists of high-frequency electromagnets producing an undulating magnetic field. The field moves at 14 km/s -- only slightly faster than the loop. A 2600 km away from the motor, the loop returns to the Earth, to be accelerated by another motor and deflected by a magnet back to space. Cargo is transported by Maglev trains riding on the loop.Dr. Adel Gastli Linear Motors 33
Small Power Linear MotorsExamples of applications textile machinery packaging machines handling machinery robot applications laboratory automation and others...
Dr. Adel Gastli
Linear Motors
34
Linear Stepper Motors Applied in RoboticsMEGAmation has over 350 Linear XY stepper motor robot heads in use throughout the world.
Pharmaceutical Automation
Automotive drive train assembly
Electronic PCB Maker
Mechanical Pick & Place Assembly
Dr. Adel Gastli
Linear Motors
35
A Wafer Linear Stepper MotorA wafer stepper is a highprecision chip manufacturing system. Modern wafer steppers are confronted with more severe demands on their performance, due to the ongoing increase of chip capacity, where performance can be defined in terms of speed and accuracy of the positioning mechanism of the stepper.
Dr. Adel Gastli
Linear Motors
36
Linear Motor Drive Men's shaver Triple Blade shaving System 1 Hour Charge Universal Voltage 12,000 Blade strokes a minute
Dr. Adel Gastli
Linear Motors
37