Continuous Levitation Research Articles

Control and Analysis of a Hybrid-Rotor Bearingless Switched Reluctance Motor with One-Phase Full-Period Suspension

In the traditional control scheme of a 12/8-pole bearingless switched reluctance motor (BSRM), radial force and torque are usually controlled as a compromise due to the conflict between their effective output areas. Additionally, each phase requires individual power circuits and is excited in turn to produce a continuous levitation force, resulting in high power device requirements and high controller costs. This paper discusses a 12/8-pole single-winding hybrid-rotor bearingless switched reluctance motor (HBSRM) with a hybrid rotor consisting of cylindrical and salient-pole lamination segments. The asymmetric rotor of the HBSRM slightly increases the complexity of its structure and magnetic circuit, but makes it possible to generate the desired radial force at any rotor angular position. A control scheme for the HBSRM is developed to utilize the independent excitation of the four windings in one phase to generate the desired levitation force at any rotor angular position, and it requires only half the number of power circuits used in the conventional control scheme of a 12/8-pole single-winding BSRM. Different from the average torque chosen to be controlled in traditional methods, this scheme directly regulates the instantaneous total torque produced by all excited phases together and presents a current algorithm to optimize the torque contribution of each phase so as to reduce torque pulsation, and the improved performance of this bearingless motor is finally validated by simulation analysis.

Design and implementation of an efficient acoustically levitated drop reactor for in stillo measurements

We present the details necessary for building an efficient acoustic drop levitator with reduced electrical power consumption and greater drop stability compared to previous designs. The system is optimized so that the levitated drop may be used as a chemical reactor. By introducing a temperature, pressure, and relative humidity sensor for feedback control of a linear actuator for adjusting resonator length, we have built a completely automated system capable of continuous levitation for extended periods of time. The result is a system capable of portable operation and interfacing with a variety of detection instrumentation for in stillo (in drop) measurements.

A new type of active-Maglev system using YBCO bulk and multiple electromagnets

We have been developing a new type of active-Maglev system that is a transporter in the vertical direction, consisting of high-temperature bulk superconductors and multiple electromagnets piled up on the vertical axis. In a previous paper, using an active-Maglev system composed of a disk-shaped YBCO bulk and five electromagnets, we have demonstrated continuous levitation and verified that its levitation height, as well as stability, can be remarkably improved by adjusting the operating current of the electromagnets individually. Electromagnetic behavior within the bulk has been also investigated numerically by a newly developed computer program based on the finite-element method adopting the Bean model. Agreement of levitation force and height between experiments and numerical analyses was good. The levitation force properties strongly depend on the field-cooling condition and the distribution and magnitude of the external magnetic field generated by the electromagnets. We clarify electromagnetic phenomena within the bulk superconductor by the computer program developed to improve the levitation properties for applications of continuous levitation to real Maglev systems.

Performance evaluation of continuous levitation in an active‐maglev system using YBCO bulk and multiple electromagnets

AbstractWe have designed and constructed a new type of active‐maglev system using YBCO bulk and two electromagnets and have demonstrated that levitation height was remarkably improved by continuous levitation. In the active‐maglev system, however, the upper and lower coils differed in the coil size and an iron plate beneath the lower coil was used to enhance the magnetic field around the bulk. Considering the real application to maglev transporter in the axial direction, we must realize continuous leviation using a larger number of electromagnets without such iron plate and enable the levitation height to be controlled freely. In this paper, we demonstrate continuous levitation while controlling the leviation height using three‐ and five‐electromagnet systems and investigate electromagnetic behavior within the bulk using an FEM computer program. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(2): 25–33, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10055

Characteristics of active-maglev system using YBCO bulk and multiple electromagnets

One useful feature of the active-maglev system is that levitation height is adjustable by varying operating current in electromagnets. To improve the levitation height, we have designed and constructed a new type of active-maglev system with two electromagnets instead of using a larger single electromagnet. The levitation height, as well as stability, was remarkably improved by adjusting the operating current of each electromagnet individually. Although the bulk is levitated up to high position, the lower electromagnet is continued to operate in continuous levitation using multiple electromagnets. It is waste that the lower electromagnet is continued to operate. The required energy for the electromagnet operation should be minimized. In this paper, we tried to realize continuous levitation with keeping the total operating current constant in five-electromagnet active-maglev system and investigate electromagnetic behavior within the bulk using a newly developed FEM computer program. Continuous levitation was successfully achieved under the desired operating condition. Agreements between experiment and analysis were excellent.

A new type of active-Maglev system using YBCO bulk and multiple electromagnets

The authors present a new type of active-maglev system consisting of a disk-shaped superconducting bulk (YBCO) and multiple electromagnets. Using the active-Maglev system composed of five electromagnets, they demonstrated continuous levitation and verified that the levitation height, as well as stability, could be remarkably improved by adjusting operating current of electromagnet individually. Electromagnetic behavior within the bulk was investigated numerically by the finite element method (FEM) adopting the Bean model. Agreements of levitation force and height between experiment and analysis were good. Suitable electromagnet operation for continuous levitation in terms of consumed operating energy was also investigated. It was found in analysis that continuous levitation could be realized efficiently by adopting a three-electromagnet operation and the operating procedure is applicable to multiple-electromagnet system. Therefore, based on the assumption of constant total operating current of three electromagnets, they numerically investigated the relationship between the operating procedure and levitation force in a five-electromagnet system as a function of levitation height. Maximum allowable weight of float (superconducting bulk and load) was evaluated through the estimation of minimum levitation force during continuous levitation as a function of air gap between electromagnets.

A new type of active-maglev system using YBCO bulk and multiple electromagnets

We present a new type of active-maglev system consisting of high-temperature superconducting bulk and multiple electromagnets. A prototype of the new active-maglev system composed of two solenoid type electromagnets located on the same axis was designed. Each electromagnet was operated individually; only the lower electromagnet had been operated until the bulk reached a certain level and then the upper electromagnet was started to operate with a constant current of the lower electromagnet. Lift and levitation height were investigated experimentally as functions of (1) the magnitude of trapped field; (2) the gap between the lower and upper electromagnets; and (3) the levitation height at which the upper electromagnet is started to operate. Independent of these parameters, `continuous levitation' in the axial direction was achieved in the new active-maglev system. Electromagnetic behavior within the bulk was also investigated numerically by the finite element method, i.e. axial symmetry field analysis, using the magnetic vector potential. The experimental and computed results imply that levitation height can be remarkably improved by the continuous levitation using multiple electromagnets.

バルク超電導体と複数の電磁石による鉛直方向連続アクティブ磁気浮上の特性評価

We have designed and constructed a new type of active-maglev system using YBCO bulk and two electromagnets and have demonstrated that levitation height was remarkably improved by continuous levitation. In the active-maglev system, however, the upper and lower coils differed in the coil size and an iron plate beneath the lower coil was used to enhance the magnetic field around the bulk. Considering the real application to maglev transporter in the axial direction, we must realize continuous leviation using a larger number of electromagnets without such iron plate and enable the levitation height to be controlled freely. In this paper, we demonstrate continuous levitation while controlling the leviation height using three- and five-electromagnet systems and investigate electromagnetic behavior within the bulk using an FEM computer program. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(2): 25–33, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10055

Frequency and phase-lag effects on transport of particulates by an AC electric field

The dynamics of a charged particulate transported by a three-phase AC electric field is analyzed. The electric field is imposed by a series of parallel electrodes disposed inside a flat dielectric panel. An exact solution for the motion equation is proposed utilizing a new technique. The investigated conditions are for the curtain mode. The analysis shows that the forces acting on the particulate are much greater near the electrodes. This and the fact that the phase lag of the displacement vis-a-vis electric force exceeds a quarter cycle cause a great repulsion force to act on the particle when it passes through the bottom half of the trajectory, whereas a smaller attraction force acts during the top half. The difference between the repulsion and attraction momentums balances gravity and results in continuous levitation. The phase lag is sensitive to the applied electrical frequency; thus, only a limited range of frequencies causes continuous levitation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Electromagnetic modelling of induction melting devices in cold crucible

An electromagnetic model is proposed for axisymmetric melting devices using cold crucibles for continuous casting or levitation. This method requires only the discretization of the electrically active parts of the induction melting process. The model takes into account the tridimensional aspect of the crucibles. Valuable information is obtained for the design of installations for melting processes in such crucibles. >

Detail and experimental results of ferromagnetic levitation system of Japan air lines HSST-01/-02 vehicles

HSST is an acronym for high-speed surface transport and is the trade name of the vehicle levitated by the attractive electromagnets and propelled by the linear induction motor (LIM) developed by Japan Air Lines. Two test vehicles have been designed, manufactured, and flight-tested. The first test vehicle, HSST-01, marked a maximum speed of 307.8 km/h on a 1300-m long test track in February, 1978, whereas the second test vehicle, HSST-02, has demonstrated boarding test flights successfully to an aggregated total of abut 1500 passengers since April, 1978, onward. The HSST-01 weighs one ton, is 4 m long, designed for high-speed testing, and incorporates eight electromagnets and a LIM with a maximum thrust of 300 kg. The levitating power supply is taken from the batteries carried on board the vehicle, and the three-phase VVVF power for the LIM propulsion is supplied from the wayside power lines through the power collector. The nine-seated HSST-02 has a loaded weight of 2.3 tons. Major items of additional functions realized in the HSST-02 include: 1) the electromagnets are fitted to the flexible chassis for better riding comfort by incorporating mechanical suspension between the chassis and the body, and 2) with the continuous levitation, the power for the LIM is rectified and supplied to the electromagnets jointly serving with the batteries carried on board. In light of the test results obtained so far, it is shown that the predicted performances of the levitation magnets, LIM, and the power collector system have been satisfactorily established, and that there would be no major technical problems in the course of our future development for implementation of the HSST system toward commercial services. The design of a preoperational test vehicle is now underway, and its test flight is scheduled to he initiated in 1980. This 80-seated preoperational test vehicle will have test flights on a 15-km test tract at a target crusing speed of 300 km/h.

Development of high speed surface transport system (IISST)

Our first electromagnetically levitated, LIM-propelled test vehicle, HSST-01, reached a maximum speed of 307.8 km/h on a 1,300-meter long test track in February, 1978, whereas our second test vehicle, HSST-02, has demonstrated manned test flights successfully covering an aggregate total of about 1,500 passengers since April, 1978. The 1-ton HSST-01, designed for high speed testing incorporates eight electromagnets and a LIM with a maximum thrust of 340 kg. The levitation power supply is taken from the vehicle-borne batteries and the 3-phase variable voltage variable frequency (VVVF) power for the LIM propulsion is supplied from wayside power lines. The 9-seat HSST- 02 has a laden mass of 2.3 tons. Additional functions realized in the 2nd test vehicle include: (1) Improved riding comfort achieved through the provision of a mechanical suspension with the electromagnets mounted on the flexible chassis. (2) A rectified power supply to the LIM enabling continuous levitation. Test results have shown that the predicted performances of the magnets, LIM and power collector system have been satisfactorily established. The design of an 80-seat pre-operational test vehicle is now underway, and its test flight is scheduled to be initiated in 1980 at a cruising speed of 300 km/h.