JPH07236205A - Rolling suppressor for vehicle in magnetic levitation train - Google Patents

Abstract

PURPOSE:To provide a safety magnetic levitation system by suppressing the rolling of vehicle at the time of running of train and reducing the eddy current heating caused by the rocking of vehicle thereby preventing a superconducting magnet from quenching. CONSTITUTION:A magnetic levitation system comprising levitation coils 2a, 2b and thrust coils 3a, 3b installed on the ground track side and a superconducting magnet mounted on a vehicle 1 is further provided with a unit 7 for detecting the rocking of the vehicle, and a controller for the amplitude or frequency of current flowing through the thrust coil. The current values and/or the driving frequencies are controlled for the thrust coils on the left and right of a track to regulate the thrust thus suppressing the rolling of the vehicle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic levitation system comprising a levitation coil and a propulsion coil installed on the ground track side, and a superconducting magnet mounted on a vehicle.

[0002]

2. Description of the Related Art In a conventional magnetic levitation system, an 8-shaped levitation coil whose right and left sides are connected by null flux cables and a racetrack type propulsion coil are installed on a ground track, and the track is superconducting. It has a structure that allows vehicles equipped with magnets to pass through. With the thrust obtained from the propulsion coil,
When the superconducting magnet of the vehicle passes through the levitation coil, an induced current generated in the levitation coil exerts a levitation force and a guiding force on the superconducting magnet of the vehicle.

The problem of vehicle swinging is caused by various factors such as air resistance and imbalance between left and right thrust forces due to installation errors of ground track side coils. On the other hand, conventionally, a null flux cable has not been provided with any means for positively suppressing the vehicle swing except for generating a guiding force in the levitation coil.

The levitation coil is a coil in which two coils placed above and below are connected in a figure eight shape. When the superconducting coil passes, induced currents in the same direction are induced in the upper and lower directions, but the electromotive force of the lower levitation coil increases by the amount of the subduction of the superconducting coil. As a result, an induced current that flows as a result of the electromotive force being canceled by the upper and lower coils flows in the 8-shaped coil. This current acts on the magnetic field of the superconducting magnet to generate a levitation force.

Null-flux cables are two cables that connect the levitation 8-shaped coils facing each other on both sides of this track, and when the vehicle approaches a track on one side,
This creates a guiding force that pushes it back into the center of the track. If the subduction of the superconducting coil is ignored, when the superconducting magnet approaches the orbit on one side, repulsive force acts on the levitation coil on the approaching side, and electromotive force of the same magnitude is generated in the same direction above and below the levitation coil. If there is no null flux cable, this electromotive force is canceled and the repulsive force does not occur in the upper and lower 8-shaped connections. However, due to the null flux cable, the current colliding at the connection point between the upper and lower coils flows through the cable and into the figure 8 coil on the opposite side.
In the facing 8-shaped coil, an attractive force acts on the superconducting magnet. For this reason, opposite electromotive forces are induced on both sides of the track, so that current can be exchanged through the null flux cable. Therefore, the repulsive force and the suction force respectively generated on both sides of the track act as a guide force for causing the vehicle to run in the center of the track, and also work in the direction of suppressing the swing of the vehicle.

However, in reality, the superconducting magnet runs with a certain amount of depression. The guide force generated by the induced current flowing through the levitation coil as described above depends on the traveling speed and the amount of sinking, and does not always act uniformly on the amount of swing of the vehicle. For example, when the traveling speed of the vehicle is low, the electromotive force is small and the guiding force is small. Therefore, conventionally, no measure has been taken to positively suppress the vehicle swing when the swing amount increases.

[0007]

The magnetic levitation system has the following requirements due to its unique properties. First, the superconducting magnet is composed of a vacuum heat insulating container, a radiant heat shield, a superconducting coil container, and a superconducting coil. The vacuum heat insulating container and the radiant heat shield are intended to prevent heat conduction from the outside and heat intrusion due to radiation, and prevent superconducting breakdown (quenching). The superconducting coil exhibits a superconducting state at a temperature below the critical temperature, but quenches when the temperature exceeds the critical temperature due to heat intrusion from the outside or eddy current heat generation of itself. When the quench occurs, the magnetic field of the magnet disappears rapidly and the levitation force,
Propulsive force cannot be obtained, which causes driving obstacles. Therefore, in order to operate the magnetic levitation system soundly, it is necessary to take thorough measures to prevent quenching.

As described above, the cause of quenching is considered to be heat intrusion from the outside and eddy current heat generation, but here, eddy current heat generation in the superconducting coil container is targeted. Eddy current heat generation is heat generation due to the generation of eddy current in response to an external magnetic field change. The magnetic field fluctuation source is, firstly, the pulsating magnetic field generated because the propulsion coil and the levitation coil are discontinuously placed, and secondly, the vacuum heat insulation container and the radiation heat shield vibrate.
A magnetic field created by an eddy current generated by crossing the static magnetic field of the superconducting coil is considered. The countermeasures against heat generated by these magnetic fields have been mainly targeted at 100 Hz to 300 Hz at which the vehicle levitates. The frequency is the frequency of the current passed through the propulsion coil and corresponds to the traveling speed of the vehicle. For example, 309 Hz is the steady running speed of the vehicle of 500 km / h.

The heat generated by the first pulsating magnetic field was very small, especially in this frequency range, and was hardly a problem. This is because the vacuum heat insulating container and the radiant heat shield are made of aluminum, which is a good electric conductor, and have an effect of shielding the superconducting coil container and the superconducting coil from the eddy current with respect to the pulsating magnetic field. Regarding heat generation by the magnetic field created by the eddy current due to the second vibration, Japanese Patent Application No. 3-59958 and
As shown in Japanese Patent Application No. 3-239900, a low electric resistance layer is attached to the superconducting coil container so that even if an eddy current flows, heat is generated within the allowable cooling capacity.
Normally, the superconducting coil is cooled by liquid helium, and the liquid helium liquefaction capacity of the on-vehicle refrigerator is 5 W per cryostat.

However, in addition to these two types of eddy current heat generation, it is necessary to consider eddy current heat generation due to vehicle swing.
Since the vehicle levitates and runs, it is ideal to run with the center of the track in the left-right direction depressed by 40 mm from the center of the levitation coil. However, the vehicle oscillates vertically and horizontally due to imbalance in air resistance and thrust. To do. Since this swing changes the amplitude of the magnetic field received from the ground coil, the magnetic field received at each part of the superconducting magnet is a wave corresponding to the amplitude and frequency of the swing, and a wave having an amplitude and frequency generated according to the traveling speed. Are like overlapping. Therefore, there are two types of eddy currents generated in each part of the superconducting magnet due to the magnetic field of the ground coil, one generated at a frequency corresponding to the traveling speed and one generated at a swing frequency. Here, the characteristic of the eddy current heat generation due to the vehicle swing is that the frequency is very low. It is empirically said that the vehicle swing is 4 to 5 Hz, and is ± 4 to 5 mm vertically and horizontally. When the heat generated in the superconducting coil container under these conditions is estimated, it is about 1 per cryostat.
It becomes 0W, which is significantly higher than the allowable value. This is 4 to 5Hz
This is because in the frequency range of, sufficient eddy currents do not flow in the vacuum insulation container and the radiant heat shield, and there is no magnetic shielding effect against the magnetic field fluctuation of the ground coil. Therefore, the superconducting coil container is directly subjected to the fluctuation of the ground coil magnetic field. Moreover, when a low electric resistance layer is attached to the superconducting coil container to reduce eddy current heat generation, sufficient eddy current flows to shield magnetic field fluctuations from the outside even in this frequency range, resulting in high heat generation. .

Conventionally, a means for reducing the heat generated in the superconducting coil container is to attach a low electric resistance layer to the superconducting coil container so that the total heat generation does not exceed an allowable value even when an eddy current flows. there were. In addition, by reducing the electrical resistance of the vacuum insulation container, etc., against an external fluctuating magnetic field, and sufficiently flowing an eddy current there, the fluctuating magnetic field applied to the superconducting coil container is shielded and eddy current is suppressed. there were. However, with regard to vehicle swing, even if pure aluminum is adhered to the superconducting coil container as a low electric resistance layer, heat generation is about 10 W, and further reduction in resistance is required.
It is difficult and impractical from various conditions. At present, the vacuum insulation container has a magnetic field shielding effect from about 20 Hz. In order to reduce this frequency to 4 Hz, the resistance of the vacuum insulation container at room temperature must be the same as that of pure aluminum at liquid helium temperature. I have to. Therefore, this is also impractical. After all, in order to reduce eddy current heat generation due to vehicle swing and prevent quenching, vehicle swing, which is the root cause, must be suppressed.

An object of the present invention is to suppress vehicle oscillation that causes heat generation in the superconducting coil container and reduce eddy current heat generation in the superconducting coil container that causes oscillation to prevent quenching. To provide.

[0013]

[Means for Solving the Problems] The above problem is a magnetic levitation system including a levitation coil and a propulsion coil installed on the ground track side, and a superconducting magnet mounted on a vehicle.
It has a device for detecting vehicle swing and a controller for controlling the current value or frequency of the propulsion coil current, and controls the current value and / or drive frequency of the propulsion coils on the left and right of the track so as to suppress vehicle swing. However, the problem is solved by providing a device for suppressing the swing of the vehicle by adjusting the thrust. Further, in a magnetic levitation system consisting of a levitation coil and a propulsion coil installed on the ground track side and a superconducting magnet mounted on a vehicle, a device for detecting the sway of the vehicle is provided, and the sway detected by the sway detection device is included. It has a calculation unit that inputs the amplitude and frequency of the motion and outputs the current value and frequency of each of the propulsion coils on the left and right of the track that acts in the direction of suppressing the oscillation, and outputs the current of the propulsion coil by the output signal from the calculation unit. Solved by providing a device that has a control device that controls the value or frequency, controls the current value and / or the drive frequency of the propulsion coils on the left and right of the track, and adjusts the thrust to suppress vehicle oscillation. To be done.

[0014]

The action of the vehicle may be caused by air resistance and imbalance of thrusts on both sides of the track due to installation errors of the ground coil. Removing the cause of vehicle sway is the most effective way to suppress sway, but as long as the vehicle is levitating, air resistance is an unavoidable phenomenon, and the vehicle always responds to the traveling speed and the amount of sinking. Move to find a balanced position. Therefore, it can be said that swinging of the vehicle is inevitable. But,
Although the oscillation itself is unavoidable, it is possible to reduce the eddy current generated in the superconducting coil container by controlling the amplitude and frequency of the oscillation to suppress heat generation and prevent quenching. As described above, the vehicle swing occurs because the train floats. The reason why the train can levitate is that attraction or repulsion acts between the magnetic field of the superconducting magnet mounted on the vehicle and the magnetic field of the ground coil. This force is, so to speak, a spring and tries to settle the vehicle at a position according to the traveling speed and weight. Therefore, in order to suppress the swing, this spring may be made rigid. In the conventional system, the spring that acts to suppress the oscillation corresponds to the magnetic field created by the induced current generated in the levitation coil. In other words, if the induced current flowing in the levitation coil is increased, the spring against rocking becomes stronger and displacement can be suppressed. However, since the levitation coil current has no power source, it cannot be controlled externally. Further, it is not realistic to provide a power source for suppressing the swing, which is costly. Therefore,
Focused on the propulsion coil. Since the propulsion coil has independent power sources on both sides of the track, it is possible to control it independently. The thrust vector generated by the propulsion coil does not completely coincide with the traveling direction but also has a guide direction component. The guide direction component of this propulsive force can act as a spring that suppresses vehicle swing. Therefore, this propulsion coil current is controlled as a means for suppressing oscillation. However, if the propulsion coil current is excessively increased, the power cost is increased, the power factor is deviated, and step out may occur. Therefore, a device for detecting the amplitude and frequency of vehicle swing is provided, and the vehicle coil swing is suppressed by increasing or decreasing the propulsion coil current so as to match the detected swing amount. In addition to the fluctuation detecting device, only the calculation unit of the current increase / decrease amount is newly added. This allows control of vehicle swing with little power and other costs. Therefore, as the swing displacement is suppressed, the eddy current heat generation is reduced, and the risk of quenching due to the temperature rise of the superconducting coil is prevented.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. 1 is a magnetic levitation train vehicle, 2 is a levitation coil group on the ground track side, and 3 is a propulsion coil group. Reference numeral 4 is a power converter that supplies power to the propulsion coil. a and b show the right side and the left side of the track with respect to the traveling direction, respectively. Reference numeral 5 denotes a sensor installed on the ground track for detecting vehicle swing, and measures the distance from the wall surface of the ground track to the vehicle. The signal detected here is sent to the swing detecting device 7 through the cable 6. In the swing detection device 7, the information on the distance from the wall surface to the vehicle sent from the sensor 5 is used as the swing amplitude and
Convert to frequency and phase information. This information is further sent to the propulsion coil current calculation unit 9 through the cable 8. The propulsion coil current calculator calculates the current value, amplitude, and phase of the propulsion coil current, which is effective in suppressing the fluctuation, for each of the left and right sides of the track, based on the fluctuation information, and outputs the signal through the cable 10. , The signal control unit 11 respectively
Send to. A control signal is sent from the signal control unit 11 to the cable 1.
2 to the electric power converter 4, and the appropriate propulsion coil current is supplied from the electric power converter 4. As a result, the swing of the vehicle is suppressed, so that the eddy current heat generation due to the swing of the vehicle is reduced, and therefore, the magnetic levitation system in which quench is less likely to occur is provided.

Another embodiment of the present invention will be described with reference to FIG. 1 is a magnetic levitation train vehicle, 2 is a levitation coil group on the ground track side, and 3 is a propulsion coil group. Reference numeral 4 is a power converter that supplies power to the propulsion coil. a and b show the right side and the left side of the track with respect to the traveling direction, respectively. Reference numeral 13 denotes an accelerometer installed in each vehicle for detecting vehicle swing, which detects swing amplitude and frequency information. The signal detected here is sent to the transmitting device 15 through the cable 14 and further to the receiving device 17 through the communication satellite 16. Information on the swing amplitude and frequency is sent from the receiving device 17 to the propulsion coil current calculation unit 9 through the cable 8. The propulsion coil current calculator calculates the current value, amplitude, and phase of the propulsion coil current, which is effective in suppressing the fluctuation, for each of the left and right sides of the track, based on the fluctuation information, and outputs the signal through the cable 10. , Respectively to the signal control unit 11. A control signal is sent from the signal control unit 11 to the power converter 4 through the cable 12, and an appropriate propulsion coil current is supplied from the power converter 4. As a result, the swing of the vehicle is suppressed, so that the eddy current heat generation due to the swing of the vehicle is reduced, and therefore, the magnetic levitation system in which quench is less likely to occur is provided.

[0017]

According to the present invention, vehicle swing can be actively suppressed by controlling the propulsion coil current.
Further, since the vehicle swing can be suppressed, the eddy current induced in the superconducting coil container is also suppressed, and therefore, it is also possible to prevent heat generation in the superconducting coil container and cause quenching.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention in the case where a ground sensor detects a swing.

FIG. 2 is an explanatory diagram of an embodiment of the present invention in the case of detecting a swing with an in-vehicle accelerometer.

[Explanation of symbols]

1 ... Magnetic levitation train vehicle, 2 ... Levitating coil group, 3 ... Propulsion coil group, 4 ... Power converter, 5 ... Oscillation detection sensor, 6,
8, 10, 12, 14 ... Cable, 7 ... Swing detection device,
9 ... Propulsion coil current calculator, 11 ... Signal controller, 16 ...
Communication satellite, 17 ... Receiving device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Teruhiro Takizawa 3-1, 1-1 Saiwaicho, Hitachi City, Ibaraki Prefecture Hitachi Ltd. Hitachi Works

Claims (4)

[Claims] 1. A magnetic levitation system comprising a levitation coil and a propulsion coil installed on the ground track side, and a superconducting magnet mounted on the vehicle, and a device for detecting the oscillation of the vehicle, and a current value of the propulsion coil. Alternatively, it has a frequency control device and controls the current value and / or the drive frequency of the propulsion coils on the left and right of the track so as to suppress the rocking of the vehicle and adjusts the thrust to thereby rock the vehicle. A vehicle sway suppression device for a magnetic levitation train, which is characterized by suppressing. 2. A magnetic levitation system comprising a levitation coil and a propulsion coil installed on the ground track side, and a superconducting magnet mounted on a vehicle, comprising a device for detecting the sway of the vehicle, and the sway detection. It has an arithmetic unit for inputting the amplitude and frequency of the oscillation detected by the device, and for outputting the current value and frequency of each of the propulsion coils on the left and right of the orbit that acts in the direction of suppressing the oscillation. A vehicle having a control device that controls the current value or frequency of the propulsion coil with an output signal, controls the current value and / or drive frequency of the propulsion coil on the left and right of the track, and adjusts the thrust to swing the vehicle. Swing suppressing device for a magnetic levitation train, which suppresses 3. The vehicle shake suppressing device for a magnetic levitation train according to claim 1, wherein the device for detecting the shake of the vehicle uses an accelerometer installed in the vehicle to suppress the shake of the vehicle. 4. The vehicle sway suppressing device for a magnetic levitation train according to claim 1, wherein a sensor installed on a track on the ground is used as a device for detecting the sway of the vehicle.