How magnetic levitation lifts and propels high-speed maglev trains, Pg11

Key Highlights:

• Maglev (magnetic levitation) trains use strong magnetic fields to lift and propel the train, eliminating rolling friction.
• This technology allows trains to achieve extremely high speeds, often exceeding 400 km/hr, while providing a smooth ride.
• Two primary levitation methods are Electromagnetic Suspension (EMS) and Electrodynamic Suspension (EDS).
• Propulsion is achieved by alternating current (AC) coils in the guideway that create shifting magnetic fields, attracting and repelling the train forward.

Detailed Insights:

• Electromagnetic Suspension (EMS) systems use electromagnets on the train's arms to attract it upwards towards the guideway, maintaining a hover height of about 10 mm.
• Electrodynamic Suspension (EDS) systems utilize superconducting magnets on the train that induce a repulsive force in track coils via electromagnetic induction when moving, hovering around 100 mm.
• EDS trains, such as Japan's SCMAGLEV, can achieve higher speeds, reaching 603 km/hr in testing, but require wheels for initial acceleration until sufficient speed is reached.
• Maglev trains use AC frequency adjustments for acceleration and deceleration, with regenerative braking diverting energy back to the grid.
• Steering is managed by side magnets that repel or attract to keep the train centered, and friction brakes or auxiliary wheels are available for emergencies.
• The primary downsides include the high cost of dedicated infrastructure, as existing tracks and stations cannot be reused, exemplified by the Shanghai Maglev costing ₹580-720 crore per kilometer.
• Despite no rolling friction, aerodynamic resistance becomes significant at speeds over 300 km/hr, necessitating aerodynamic designs.
• Magnetic levitation principles are also applied in high-speed turbines, aircraft carrier launch systems, and precision factory automation.

Scientific/Technical Concepts Involved:

• Magnetic Levitation: The process of suspending an object in the air using only magnetic fields, counteracting gravitational force.
• Electromagnetic Suspension (EMS): A levitation method where electromagnets on the train attract it upwards towards a ferromagnetic guideway.
• Electrodynamic Suspension (EDS): A levitation method using superconducting magnets on the train to induce repulsive magnetic fields in the track, pushing the train upwards.
• Electromagnetic Induction: The production of an electromotive force across an electrical conductor in a changing magnetic field.