1. Schematic Design of the System Creation of the Magnetic Field
HALBACH ARRAYS IN THE INDUCTRACK SYSTEM FOR MORE EFFICIENT AND SAFER RAIL TRAVEL
By:
Ryan Schwartz
Safety of Passengers
Vehicle Stability
Schematic Design of the System
Comparison of Maglev Systems, showing why the Inductrack is the best choice for Maglev Systems
Magnetic fields exposed to the passengers on the Inductrack is minimal. This is mainly due to the fact that only permanent magnets are used in the system. There is no outside source of magnetism being used so the magnetic fields being created are kept to a minimum in the train. Also, the Halbach Arrays revolutionary design helps to keep very little to none of the magnetic field above the system. The use of Halbach Arrays virtually shields passengers from magnetic fields while contributing all the power to the movement of the train.
The creation of horizontal, but opposing magnetic fields create a stable ride. Once the velocity is larger than the threshold speed, the lift to drag ratio will keep the vehicle stably levitated. If for some reason the ride becomes unstable due to outside conditions, or there is a power failure of the train, the vehicle will simply slow down until it is rested onto the auxiliary wheels. The lift to drag ratio is dependent on velocity, so a power failure will not cease motion in the train.
Electromagnetic
Systems
Electrodynamic
Inductrack
- Use of actively controlled electromagnets for levitation and propulsion using attractive forces.
- Use of electromagnets, which use repulsive force in order to propel and levitate the vehicle.
- Use of permanent magnets and tightly coiled conductors to create levitation and propulsion using attractive forces.
- Require actively controlled direct current electromagnets. Without control of current, the system is unstable.
- Highly undampered, which can cause instability and low ride quality.
- High ride quality. Layout of Halbach Arrays allow for maximum stability during travel.
- Two options to control the current, either a fast-acting current control, which limits controllability, or flux control, which cannot control size of the air gap.
- Suspension system can be inefficient, and lose lots of power while in operation.
- No input energy is required during travel due to electromagnetic induction.
- Control of the system must be precise and optimized in order to keep a minimal air gap between the track and the vehicle.
- Magnetic fields from superconductors must be shielded in order to protect on board electronic devices.
- Lift to drag ratio can reach 200 to 1 and varies with velocity, allowing for very efficient levitation.
Creation of the Magnetic Field
Shown above is a diagram of the layout of the Inductrack system. Above the support structure is the track made of tightly coiled wire or another conductor. The wire coils parallel the rails of a traditional rail system. Under the car, there are two Halbach Arrays on each side. The arrays facing downward help to levitate and aid in propulsion of the system. Each array on the side aids in lateral stability of the vehicle over the track.
Strength of Magnets
The permanent magnets used in the Inductrack are some of the strongest available. Magnets made of neodymium have been used in test runs and it has been shown that levitation forces of 40 metric tons per square meter are possible with 800 kilograms of magnets per square meter. This translates to fifty times the weight of the magnets possible for levitation
As shown in figure one, the layout of the Halbach Arrays in the Inductrack is quite simple. The permanent magnets create a periodic magnetic field near the lower surface of the array. This arrangement of permanent magnets allows for cancelling out the magnetic field above the array, while creating a nearly perfect sinusoidal varying magnetic field below the array. For comparison, the magnetic field created is very similar to an LR circuit, causing a perfectly fluctuating field inside of the inductor.
Lift to Drag Ratio
𝐿/𝐷 = 2𝜋𝑣𝑙/ λ𝑅
This equation above describes the lift to drag ratio of the Inductrack system. L/D is the lift to drag ratio, l is the length in meters of the Halbach Array, λ is the wavelength of the array, and R is the resistance of the track. In traditional airplanes, the lift to drag ratio varies little to none with a change in velocity. In addition, the L/D ratio of the wing of a jet aircraft is about 25 to 1. A large factor of the lift to drag ratio of the Inductrack is that it depends on the velocity. The Inductrack needs to reach a threshold speed, in which the lift is equal to the drag. After the threshold is reached, the L/D ratio rapidly increases which causes the levitation of the car to become stable. The lift to drag ratio of an Inductrack train can get very high, about 200 to 1 at a velocity of 500 kilometers per hour.