The disclosure relates to electrodynamic maglev vehicles and, more particularly, to radial and axial electrodynamic wheel (EDW) maglev vehicles that can stably levitate and translate above a low-cost U-guideway.
Electrodynamic maglev vehicles use magnets to induce currents within conductive track material. The induced currents create an opposing field which can be utilized to create levitation, thrust, and guidance forces. Electrodynamic maglev vehicles are being studied for use in ultra-high-speed ground transportation applications as well as in lower speed maglev vehicles. Maglev vehicles offer trip times that are competitive with aircraft and can be powered with electricity created from renewable energy sources. Maglev vehicles' non-contact operation allows them to operate in harsh environments and operate on steep gradients. To lower the cost of maglev transportation the maglev track can be passive. To accomplish this the maglev vehicle can be the initial field source, rather than the track.
Inducing current within a passive conductive track guideway by rotating magnets, rather than simply translating magnets, enables both a lift and thrust force to be simultaneously created. The use of rotating magnets can create a relatively high lift-to-weight ratio. In addition, when using magnets, the reactive field setup between the conductive track and magnet rotor is shielded from the driving motor.
In the past, both radial and axial electrodynamic wheel (EDW) configurations, as illustrated in
The axial rotor EDW has a uniform airgap with the flat track leading to a higher lift-to-weight ratio, but no thrust force is then created. To additionally produce thrust, the axial rotor can be tilted, creating a non-uniform air-gap and asymmetric current flow, or the axial rotor can create thrust by using the track edge-effect. This also creates an asymmetric current flow. While these axial EDW designs allow the axial EDW to create thrust, they will also significantly lower the lift force, reducing the benefits of the axial EDW relative to the radial configuration. By adding a rotor shield or adding supplemental rotor windings a rotor magnet field asymmetry can be created, reducing the field on one side of the magnet rotor; this can then give rise to a thrust force. But the use of a conductive rotor magnet shield will greatly increase loss and the addition of rotor windings around the magnets will significantly increase complexity as well as loss.
Both the radial and axial EDWs are laterally unstable when placed over a flat guideway sheet. If a single flat track is used, like that shown in
where ig is the induced loop current and im=fictious magnet current that creates the magnet field. Since Mtm=Mmt the energy in terms of mutual flux is:
E
m(x,z)=Φ(x,z)im Eq. (2)
where Φ=Mtmit. The magnetic force acting on the guideway in the lateral z-axis direction can be obtained from the negative energy gradient:
Thus, assuming that the magnet source current is not changing and then substituting equation (2) into equation (3) the lateral force will be:
From Equation (4) it can be noted that the lateral force will depend on the gradient of the mutual flux. For the magnet guideway configuration shown in
To provide passive stability, the maglev's magnets need to rest within a mutual energy minimum. One way to create a local energy minimum is to use a split-track guideway. However, by splitting the track, the currents are prevented from circulating below the maximum rotor field location and therefore the split-track greatly reduces the lift and thrust force. The amount of re-centering force is also relatively small and does not scale well with size. Lateral stability can also be created by using a curved track; however, for track design, the EDW does not create thrust and the use of any curved, or wrap-around track, greatly increase the guideway construction and operating cost. Since to enable vehicle lane changing the entire guideway must be moved.
It has also been proposed that active control could be used to create stability, by mechanically rotating the EDW's axis the EDW force direction can be constantly adjusted so as to enable the EDW to be maintained on a single flat guideway; if the EDW rotation controls failed it would lead to a catastrophic crash (like with some aircrafts).
It should be understood that the brief description above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
The disclosure may be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below:
Embodiments of the disclosed technology are generally directed to an L-track electrodynamic wheel (EDW) typology in which two L-tracks are combined to form a U-guideway and an EDW-maglev vehicle can have 6-degrees-of-freedom stability. Each EDW can be composed of a simple one pole-pair diametrically magnetized rotor magnet. In certain alternative embodiments, a higher number of EDW rotor pole-pairs can be used.
As described herein, the radial and axial EDW forces are defined using the coordinate axis with respect to the rotor axis shown in
Using the geometric parameters shown in Table I and Table II below, the forces created between the L-track and the rotating one-pole pair EDW were computed using a 3-D transient finite element analysis (FEA) model developed in JMAG.
To create a recentering force regardless of axial position, a U-track guideway can be used. A front-view of a U-track EDW maglev that contains radial EDWs is shown in
zg1=zg2=zg3=zg4=6.35 mm Eq. (5)
where zg1 and zg2 are the distances from the EDW and left-side track and zg3 and zg4 are the distances from the right-side track. Only the zg1 and zg3 distances are shown in the front-view in
z
c=(zg1+zg2−zg3−zg4)/4 Eq. (6)
The EDW rotor's thrust and lift force add when the rotors are offset, and the vehicle lateral force can be defined as:
F
zc(zc)=Fz1(zg1)+Fz2(zg2)−Fz3(zg3)−Fz4(zg4) Eq. (7)
The EDW-vehicle recentering axial force is highly linear and the calculated axial stability occurs when ly≥10.9 mm. This cross-over length can be more clearly seen in
The increase in lift as the track-side height increases improves the lift-to-weight ratio, this improvement is illustrated by
where m=magnet mass. The lift force is created from the currents induced on the track edge, pushing the EDW upwards, off the track edge. This increase in lift comes at an increase in lift specific power (W/kg), as illustrated by
The lift specific power can be defined as:
where PL=total electrical track loss. It should be noted that the lift specific power is relatively high. This is because of the small diameter used as well as the high angular speed selected for the force analysis.
An axial EDW-maglev vehicle and a radial EDW-maglev vehicle are illustrated by
Maglev vehicles that use translationally moving magnets to create electrodynamic levitation can experience instability at different operating speeds. As the EDW vehicle has a slip speed, as well as translational speed, and these two speeds can be independently changed the EDW vehicle could more easily overcome instability induced at particular operating speeds.
In an exemplary embodiment, an electrodynamic wheel (EDW) vehicle can include: a vehicle mount configured to transport a load such as cargo, passengers, or both; a plurality of motors mechanically coupled with the vehicle mount; at least one battery mechanically coupled with the vehicle mount and configured to provide power to the plurality of motors; and a plurality of EDWs coupled with the vehicle mount, wherein each of the plurality of EDWs includes a magnet and a rotor configured to be rotated by a corresponding one of the plurality of motors, further wherein the EDWs are configured to magnetically levitate over a U-guideway.
In certain examples of the EDW vehicle, the plurality of motors includes brushless direct current (BLDC) motors. In additional examples of the EDW vehicle, the plurality of EDWs includes four radial rotors. In some examples of the EDW vehicle, the plurality of EDWs includes four axial rotors.
In certain embodiments of the EDW vehicle, the U-guideway includes a plurality of sections of L-track; the plurality of sections of L-track includes aluminum sheets; alternatively or in addition thereto, the plurality of sections of L-track are configured to provide lateral recentering force; alternatively or in addition thereto, the plurality of sections of L-track are configured to increase thrust and lift force. Each rotor may be controlled via wired or wireless mechanisms
In another embodiment, a system can include a U-guideway and an electrodynamic wheel (EDW) vehicle, the EDW vehicle having: a vehicle mount configured to transport a load; a plurality of motors mechanically coupled with the vehicle mount; at least one battery mechanically coupled with the vehicle mount and configured to provide power to the plurality of motors; and a plurality of EDWs coupled with the vehicle mount, wherein each of the plurality of EDWs includes a magnet and a rotor configured to be rotated by a corresponding one of the plurality of motors, further wherein the EDWs are configured to magnetically levitate over the U-guideway. In some aspects, the plurality of motors includes brushless direct current (BLDC) motors. In additional aspects, the plurality of EDWs may include a plurality of rotors, for example four radial rotors and or axial rotors.
In certain embodiments of the system, the U-guideway includes a plurality of sections of L-track; the plurality of sections of L-track includes aluminum sheets; alternatively or in addition thereto, the plurality of sections of L-track are configured to provide lateral recentering force; alternatively or in addition thereto, the plurality of sections of L-track are configured to increase thrust and lift force.
The description of embodiments has been presented for purposes of illustration and description. Suitable modifications and variations to the embodiments may be performed in light of the above description or may be acquired from practicing the methods. The methods may be performed by executing stored instructions with one or more logic devices (e.g., processors) in combination with one or more hardware elements, such as storage devices, memory, hardware network interfaces/antennas, switches, actuators, clock circuits, and so on. The described methods and associated actions may also be performed in various orders in addition to the order described in this application, in parallel, and/or simultaneously. The described systems are exemplary in nature, and may include additional elements and/or omit elements. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and/or properties disclosed.
As used herein, the terms “system” or “module” or “modulator” may include a hardware and/or software system that operates to perform one or more functions. For example, a module or system may include a computer processor, controller, or other logic-based device that performs operations based on instructions stored on a tangible and non-transitory computer readable storage medium, such as a computer memory. Alternatively, a module or system may include a hard-wired device that performs operations based on hard-wired logic of the device. Various modules or units shown in the attached figures may represent the hardware that operates based on software or hardwired instructions, the software that directs hardware to perform the operations, or a combination thereof.
The foregoing described aspects depict different components contained within, or connected with different other components. It is to be understood that such depicted architectures are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being “operably connected,” or “operably coupled,” to each other to achieve the desired functionality.
As used in this application, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is stated. Furthermore, references to “one embodiment” or “one example” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. The terms “first,” “second,” “third,” and so on are used merely as labels, and are not intended to impose numerical requirements or a particular positional order on their objects. The following claims particularly point out subject matter from the above disclosure that is regarded as novel and non-obvious.
This application claims priority to U.S. Provisional Application No. 63/384,392, entitled “ELECTRODYNAMIC WHEEL MAGLEV VEHICLE WITH A PASSIVE U-GUIDEWAY,” and filed Nov. 18, 2022, the entire contents of which are hereby incorporated by reference for all purposes.
This invention was made with government support under Grant No. 1810489 awarded by the National Science Foundation. The U.S. Government has certain rights in the invention.
Number | Date | Country | |
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63384392 | Nov 2022 | US |