Maglev Report 635y26

Submitted by: ASHOKA KUMAR MISHRA Regd. Number: 0521106012

DEPARTMENT OF ELECTRICAL ENGG.

Department of Electrical Engineering CERTIFICATE This is a bonafide record of Seminar Report entitled “MAGNETIC LEVITATION & BULLET TRAINS”. This seminar was presented satisfactorily at department of Electrical Engineering, College of Engineering and Technology, Bhubaneswar by Mr. Ashoka Kumar Mishra, Regd no: 0521106012 in partial fulfillment of requirement for his 7th semester Bachelor of Technology degree examination under Biju Pattnaik University of Technology, Orissa. This report has not been submitted for any other examination and does not form part of any other course undergone by the candidate.

Seminar supervisor

Professor in charge

In presenting seminar on “MAGNETIC LEVITATION & BULLET TRAINS” I would like to convey my deep sense of gratitude to those who helped me a lot in preparing this seminar. At the outset I would like to thank HOD of Electrical engg. Department Prof P.K. Satapathy for his timely suggestion in preparing this seminar. I also like to thank Er. B.M. Das and Dr. D.P. Bagatry for his valuable suggestions and guidance. I would also like to thank all faculty member of Electrical Engg. Department who have been of immese help and in going through every minute detail of this seminar report and in providing valuable guidance every now and then. I would like to thank my friends for their and co-operation and encouragement through out the seminar preparation till the entire presentation process.

Ashoka Kumar Mishra Regd no.:0521106012

7th Semester. Electrical Engg.

 INTRODUCTION  MAGLEV METHODS  WORKING OF MAGLEV VEHICLE  BRAKING AND CONTROL SYSTEM  ADVANTAGES AND DISADVANTAGES  COMPARISON  RESEARCH  BIBLIOGRAPHY

INTRODUCTION Magnetic levitation, maglev, or magnetic suspension is a method by which an object is suspended above another object with no other than magnetic field .The electromagnetic force is used to counteract the effects of the gravitational force. A substance which is diamagnetic repels a magnetic field. Earnshaw's theorem does not apply to diamagnets; they behave in the opposite manner of a typical magnet due to their relative permeability of μr < 1. All materials have diamagnetic properties, but the effect is very weak, and usually overcome by the object's paramagnetic or ferromagnetic properties, which act in the opposite manner. Any material in which the diamagnetic component is strongest will be repelled by a magnet, though this force is not usually very large. Diamagnetic levitation can be used to levitate very light pieces of pyrolytic graphite or bismuth above

a moderately strong permanent magnet. As water is predominantly diamagnetic, this technique has been used to levitate water droplets and even live animals, such as a grasshopper and a frog.

The minimum criteria for diamagnetic levitation is where: •

χ is the magnetic susceptibility

•

ρ is the density of the material

•

g is the local gravitational acceleration (-9.8 m/s2 on Earth)

•

μ0 is the permeability of free space

•

B is the magnetic field is the rate of change of the magnetic field along the

•

vertical axis

Assuming ideal conditions along the z-direction of solenoid magnet:

•

Water levitates at

•

Graphite at

,

Figure showing a live frog levitating inside a 32 mm diameter vertical bore in a magnetic field of about 16 teslas at the Nijmegen High Field Magnet Laboratory.

MAGLEV METHODS • Repulsion between like poles of permanent magnets or electromagnets. • Repulsion between a magnet and a metallic conductor induced by relative motion. • Repulsion between a metallic conductor and an AC electromagnet. • Repulsion between a magnetic field and a diamagnetic substance. • Repulsion between a magnet and a superconductor. • Attraction between unlike poles of permanent magnets or electromagnets. • Attraction between the open core of an electromagnetic solenoid and a piece of iron or a magnet. • Attraction between a permanent magnet or electromagnet and a piece of iron. • Attraction between an electromagnet and a piece of iron or a magnet, with sensors and active control of the current to the electromagnet used to maintain some distance between them.

• Repulsion between an electromagnet and a magnet, with sensors and active control of the current to the electromagnet used to maintain some distance between them.

WORKING OF MAGLEV VEHICLE Basically the construction depends on 3 different working forces. • PROPULSION FORCE • LEVITATING FORCE • LATERAL GUIDING FORCE

PROPULSION FORCE: This is a horizontal force which causes the movement of train. It requires 3 parameters. • Large electric power supply • Metal coil lining, a guide way or track. • Large magnet attached under the vehicle.

PRINCIPLES OF LINEAR MOTOR Its principle is similar to induction motor having linear stator and flat rotor. The 3-phase supply applied to the stator produces a constant

speed magnetic wave, which further

produces a repulsive force. Maglev vehicles are propelled primarily by one of the following three options: 1.A linear synchronous motor (LSM) in which coils in the guideway are excited by a three phase winding to produce a traveling wave at the speed desired; Trans Rapid in employs such a system. 2. A Linear Induction Motor (LIM) in which an electromagnet underneath the vehicle induces current in an aluminum sheet on the guideway.

3. A reluctance motor is employed in which active coils on the vehicle are pulsed at the proper time to realize thrust.

LEVITATING FORCE: The levitating force is the upward thrust which lifts the vehicle in the air. There are 3 types of levitating systems 1. EDS system 2. EMS system 3. INDUCTRACK system

Levitating force is produced due to the eddy current in the conducting ladder by the electromagnetic interaction. At low speed the force due to induced poles cancel each other. At high

speed a repulsive force is taken place as the magnet is shifted over a particular pole. 1. EDS SYSTEM: In EDS both the rail and the train exert a magnetic field, and the train is levitated by the repulsive force between these magnetic fields. At slow speeds, the current induced in these coils and the resultant magnetic flux is not large enough to the weight of the train. For this reason the train must have wheels or some other form of landing gear to the train until it reaches a speed that can sustain levitation. Onboard magnets and large margin between rail and train enable highest recorded train speeds (581 km/h).This system is inherently stable. Magnetic shielding for suppression of strong magnetic fields and wheels for travel at low speed are

required. It can’t produce the propulsion force. So, LIM system is required.

2. EMS SYSTEM: Maglev concepts using electro -magnetic suspension employ attractive forces. Magnetic fields inside and outside the vehicle are insignificant; proven, commercially available technology that can attain very high speeds (500 km/h); no wheels or secondary propulsion system needed. The separation between the vehicle and the guideway must be constantly monitored and corrected by computer systems to avoid collision due to the unstable nature of electromagnetic attraction. 3. INDUCTRACK SYSTEM: The inductrack guide way would contain two rows of tightly packed levitation coils, which would act as the rails. Each

of these “rails” would be lined by two Halbach arrays carried underneath the maglev vehicle: one positioned directly above the “rail” and one along the inner side of the “rail”. The Halbach arrays above the coils would provide levitation while the Halbach arrays on the sides would provide lateral guidance that keeps the train in a fixed position on the track. The track is actually an array of electrically-shorted circuits containing insulated wire. In one design, these circuits are aligned like rungs in a ladder. As the train moves, a magnetic field repels the magnets, causing the train to levitate. There are two inductrack designs. Inductrack I and II. Inductrack I is designed for high speeds, while inductrack II is suited for slow speeds. Inductrack trains could levitate higher with greater stability. As long as it’s moving a few miles per hour, an inductrack train will levitate nearly an inch above the track. A greater gap above the track means that the train would not require complex sensingsystems to maintain stability.Permanent magnets had not been used before because scientists thought that they

would not create enough levitating force. The inductrack design byes this problem by arranging the magnets in a Halbach array. The magnets are configured so that the intensity of the magnetic field concentrates above the array instead of below it which generates higher magnetic field. The inductrack II design incorporates two Halbach arrays to generate a stronger magnetic field at lower speeds. Dr. Richard post at the Livermore National Laboratory in California came up with this concept in response to safety and cost concerns. The prototype tests caught the attention of NASA, which awarded a contract to Dr.post and his team to explore the possibility of using the inductrack system to launch satellites into orbit.

LATERAL GUIDING FORCE: Guidance or steering refers to the sideward forces that are required to make the vehicle follow the guideway. The necessary forces are supplied in an exactly analogous fashion to the suspension forces, either attractive or repulsive. The same magnets on board the vehicle, which supply lift, can be used concurrently for guidance or separate guidance magnets can be used. It requires the following arrangements:

• Guideway levitating coil •

Moving magnet