JP2013055733A - Operation method of superconductive rotating machine and superconductive rotating machine system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operation method capable of operating a superconductive rotating machine in a self-supporting stable manner.SOLUTION: A superconductive rotating machine comprises: a rotator having superconductive squirrel-cage winding in which a rotor bar and an end ring are formed by a superconducting wire rod. When a rotational state of a rotator is shifted from a first rotational state of a first torque and a first number of rotations to a second rotational state of a second torque and a second number of rotations that are the same or different from the first ones, control to increase a ratio of applied voltage and its frequency to primary winding of the superconductive rotating machine is performed, and a current more than a critical current is caused to flow in the superconductive squirrel-cage winding of the rotator in the first rotational state so as to be once in a magnetic flux flow state. When the magnetic flux flow state is realized, the ratio of the applied voltage and the frequency is set to a value corresponding to a second rotational state so that shift is made to the second rotational state.

Description

  The present invention relates to a method of operating a superconducting rotating machine using a high-temperature superconducting material for a secondary-side cage winding.

  In a cage induction machine with an existing configuration, by using a high-temperature superconducting material for the secondary-side cage winding, a superconducting rotary machine (high-temperature superconductivity) that can perform synchronous rotation in addition to induction rotation while having an induction machine configuration. An induction synchronous rotating machine (HTS-ISM) is already known (for example, see Patent Document 1).

International Publication No. 2009/116219

  In the case of an existing normal lead-type induction machine, if the secondary-side squirrel-cage winding resistance is decreased, the rotation becomes unstable when the excitation speed exceeds a certain threshold, and the rotation control becomes impossible. It is known that.

  Also in the case of the superconducting rotating machine disclosed in Patent Document 1, since the secondary-side cage winding is made of a high-temperature superconducting material, its resistance is very small in the superconducting state. Therefore, there is a problem that the synchronous rotation is likely to be unstable (vibrational). In particular, the problem related to the variable speed was remarkable. However, in Patent Document 1, there is no disclosure or suggestion regarding such a problem and its solution.

  Note that Patent Document 1 uses a magnetic flux flow state when a superconducting cage winding in a stationary state is in a superconducting state without capturing a magnetic flux of a rotating magnetic field by a stator winding. However, there is no disclosure or suggestion regarding the realization of stable control of synchronous rotation.

  This invention is made | formed in view of the said subject, and it aims at providing the driving | running method which can operate a superconducting rotary machine independently and stably.

  In order to solve the above-mentioned problems, the invention of claim 1 is a method of operating a superconducting rotating machine comprising a rotor having a superconducting lead-shaped winding in which a rotor bar and an end ring are made of a superconducting wire. From the first rotational state of the first torque and the first rotational speed to the second torque and the second rotational speed that are the same as or different from the first torque and the first rotational speed. When the transition to the rotational state of 2 is performed, the superconducting lead-shaped winding of the rotor in the first rotational state is controlled by controlling the voltage applied to the primary winding of the superconducting rotating machine and its frequency. The wire is once brought into a magnetic flux flow state and then shifted to the second rotation state.

  The invention according to claim 2 is the operation method of the superconducting rotating machine according to claim 1, wherein the ratio between the applied voltage and the frequency is increased and a current higher than a critical current flows through the superconducting lead-type winding. By doing so, the magnetic flux flow state is realized, and when the magnetic flux flow state is realized, the ratio between the applied voltage and the frequency is set to a value corresponding to the second rotation state. And

  According to a third aspect of the present invention, there is provided a superconducting rotating machine comprising a rotor having a superconducting lead-shaped winding in which a rotor bar and an end ring are made of a superconducting wire, a stator including a primary winding, and the superconducting rotating machine. A superconducting rotating machine system comprising: a controller for controlling the operation, wherein the rotation state of the rotor is changed from the first torque and the first rotation state of the first rotation number to the first torque and the first rotation state. The controller controls the voltage applied to the primary winding and its frequency when shifting to the second rotation state of the second torque that is the same as or different from the rotation number of 1 and the second rotation state of the second rotation number. Thus, the superconducting lead-shaped winding of the rotor in the first rotation state is once brought into a magnetic flux flow state and then shifted to the second rotation state.

  A fourth aspect of the present invention is the superconducting rotating machine system according to the third aspect, wherein the controller increases a ratio of the applied voltage to the frequency to cause a current exceeding a critical current to the superconducting cage winding. The magnetic flux flow state is realized by causing the magnetic flux to flow, and when the magnetic flux flow state is realized, the ratio between the applied voltage and the frequency is set to a value corresponding to the second rotational state. It is characterized by.

  According to the first to fourth aspects of the present invention, the instantaneous rotation of the induced torque in the magnetic flux flow state is used to instantaneously change the speed of the superconducting rotating machine in the synchronous torque of the superconducting rotating machine. The rotation operation can be continued stably. That is, the superconducting rotating machine can be operated independently and stably.

It is sectional drawing containing the rotating shaft direction of the superconducting rotary machine 1 which is a control object in the control method of this invention. FIG. 4 is a cross-sectional view of a cross section perpendicular to the rotation axis direction of the rotor 7. FIG. 3 is a view showing the rotor core 71. It is a figure which shows the superconducting induction | guidance | derivation cage winding 73. FIG. It is a figure which shows the normal-electric guide | clad winding 74. FIG. It is a figure which shows the torque characteristic of a superconducting electromotive motive. 1 is a diagram showing a schematic configuration of a superconducting rotating machine system 100 in which a superconducting rotating machine 1 is incorporated. It is a figure which shows the current-voltage characteristic of the superconducting lead-shaped winding 73 of the superconducting rotating machine 1. It is a figure which contrasts an analysis result and measured value about the no-load characteristic and load characteristic of superconducting rotating machine 1. It is a figure which shows the result of having analyzed the stability limit of the synchronous rotation of the superconducting rotary machine. It is a figure which shows the result of having analyzed the stability of the synchronous rotation at the time of no load. It is a figure which shows the result of having analyzed the stability of the synchronous rotation at the time of no load.

<Configuration of superconducting rotating machine>
FIG. 1 is a cross-sectional view including the rotation axis direction of a superconducting rotating machine 1 to be controlled in the control method of the present invention. Generally speaking, the superconducting rotating machine 1 is a squirrel-cage induction machine that uses a high-temperature superconducting material for a secondary-side cage winding. As shown in FIG. 1, the superconducting rotating machine 1 mainly includes a casing 2, a stator 3, brackets 4 a and 4 b, and a rotor 7.

  The stator 3 includes an annular stator core 3a and a stator winding (primary winding) 3b provided in a slot (not shown) of the stator core 3a. The stator core 3a is formed by laminating electromagnetic steel plates such as silicon steel plates in the axial direction. The stator winding 3b is made of a normal conductive material.

  The rotor 7 is arranged inside the stator 3 (stator iron core 3a) and separated from the stator 3. The rotor 7 includes a rotor core 71, a superconducting lead-shaped winding 73, a normal conducting lead-shaped winding 74, and a rotating shaft 75. FIG. 2 is a cross-sectional view of a cross section perpendicular to the rotation axis direction of the rotor 7.

  FIG. 3 is a view showing the rotor core 71. The rotor core 71 is a hollow cylindrical member as shown in FIG. 3 and is formed by laminating electromagnetic steel plates such as silicon steel plates in the axial direction. As shown in FIGS. 2 and 3, a rotation shaft receiving hole 71 a is formed at the shaft center portion of the rotor core 71, and a round bar-shaped rotation shaft 75 is inserted and attached thereto. Further, in the vicinity of the outer periphery of the rotor core 71, a plurality of slots 72 penetrating in the axial direction are formed at predetermined intervals in the circumferential direction. The slot 72 is formed obliquely with respect to the axial direction of the rotor core 71 (the extending direction of the rotary shaft 75), and has an oblique slot (skew) configuration. However, it is not an essential aspect that the slot 72 has a skew configuration in the present invention. As shown in FIG. 1, the slot 72 accommodates the rotor bar 73 a of the superconducting lead-shaped winding 73 and the rotor bar 74 a of the normal conducting lead-shaped winding 74.

  FIG. 4 is a diagram showing the superconducting lead-shaped winding 73. As shown in FIG. 4, the superconducting lead-shaped winding 73 includes a plurality of rotor bars 73a and a pair of end rings 73b and 73b that short-circuit both ends of each rotor bar 73a.

  More specifically, the rotor bar 73a is a member having a rectangular shape in cross section, which is formed by bundling a plurality of superconducting wires. However, it is not an essential aspect that the cross section is rectangular. For example, the cross sectional view may be circular. The superconducting wire is formed by coating a plurality of high-temperature superconducting filaments with a highly conductive metal such as copper, aluminum, silver, or gold. Although it is preferable to use a high-temperature superconducting filament made of a bismuth-based high-temperature superconducting material, an embodiment using a filament made of another high-temperature superconducting material may be used.

  The end ring 73b is an annular member made of a superconducting wire like the rotor bar 73a. Each end of the rotor bar 73a is soldered to the pair of end rings 73b and 73b.

  FIG. 5 is a diagram showing the normal conducting lead-shaped winding 74. As shown in FIG. 5, the normal conducting lead-shaped winding 74 includes a plurality of rotor bars 74a and a pair of end rings 74b and 74b that short-circuit both ends of each rotor bar 74a.

  The rotor bar 74a is a member having a rectangular shape in cross section made of a highly conductive material such as copper, aluminum, silver, or gold. However, it is not an essential aspect that the cross section is rectangular. For example, the cross sectional view may be circular. Similarly to the rotor bar 74a, the end ring 74b is also made of a highly conductive material such as copper, aluminum, silver, or gold. Each end of the rotor bar 74a is soldered to the pair of end rings 74b and 74b.

  The rotor bar 73 a and the rotor bar 74 a are disposed at a predetermined interval in the circumferential direction and obliquely with respect to the axial direction of the superconducting lead-shaped winding 73. Thereby, both the superconducting lead-shaped winding 73 and the normal conducting lead-shaped winding 74 are cylindrical and have a skew structure. Moreover, the rotor bar 73a and the rotor bar 74a are disposed in all slots 72 provided in the rotor core 71 without excess or deficiency. However, as shown in FIGS. 1 and 2, in the slot 72, the rotor bar 74a is disposed outside the rotor bar 73a.

  Further, the rotor bar 73 a and the rotor bar 74 a are longer than the slot 72. Therefore, as shown in FIG. 1, the rotor bar 73 a and the rotor bar 74 a protrude from the slot 72 in the state of being accommodated in the slot 72.

  The casing 2 is a cylindrical member that covers the outer periphery of the stator 3 (more precisely, the stator core 3a). Further, the brackets 4 a and 4 b are substantially disk-shaped members that are fitted into the two end portions of the casing 2 that are open. However, a through hole 4h through which the rotary shaft 75 passes is provided at the center of the bracket 4a. The brackets 4a and 4b are provided with bearings 5a and 5b such as bearings for rotatably supporting the rotary shaft 75.

<Basic operation of superconducting rotating machine>
Next, it is a figure explaining the operation | movement aspect of the superconducting rotary machine 1 which has the above structures. FIG. 6 is a diagram showing torque characteristics of the superconducting motive (change in torque T with respect to slip s). The phases F1, F2, and F3 in the torque characteristics shown in FIG. 6 respectively correspond to three situations in which the combination of the conduction state of the superconducting lead-shaped winding 73 and the rotation mode of the rotor 7 is different.

  First, when the superconducting lead-shaped winding 73 is in a normal conducting state (non-superconducting state), an induced current flows through the normal conducting lead-shaped winding 74 due to the rotating magnetic field generated by the stator 3 to generate an induction torque. In this case, the rotor 7 rotates by the induced torque main drive. The torque characteristic at this time is shown by phase F1 in FIG.

  In a state where the superconducting rotating machine 1 performs such induction rotation, a slight induced current also flows through the superconducting lead-shaped winding 73. However, due to the difference in resistance value between the superconducting lead-shaped winding 73 and the normal conducting lead-shaped winding 74 in the normal conducting state, in this state, the induced current flowing through the normal conducting lead-shaped winding 74 is more superconducting lead-shaped. It is much larger than the induced current flowing through the winding 73. Therefore, the induced torque generated in the normal conducting lead winding 74 is more dominant in the rotation of the rotor 7 than the induced torque generated in the rotor 7 superconducting conducting winding 73.

  Next, when the superconducting lead-shaped winding 73 transitions from the normal conducting state to the superconducting state, the superconducting lead-shaped winding 73 enters a magnetic flux trapping state in which the magnetic flux of the rotating magnetic field by the stator 3 is trapped. Arise. At this time, the rotor 7 rotates by the synchronous torque main drive. The torque characteristic at this time is shown by phase F2 in FIG.

  During this synchronous rotation, an extremely slight slip may occur due to the influence of the connection resistance between the rotor bar 73a and the end ring 73b. However, in this case as well, it can be considered that synchronous rotation is performed as a device characteristic.

  In addition, when an excessive load is applied to the superconducting rotating machine 1 in the state of synchronous rotation in this way, the superconducting lead-shaped winding 73 shifts from the magnetic flux capturing state to the magnetic flux flow state. The rotation is continued with the induced torque main drive. The induction torque at this time is provided from both the superconducting lead-shaped winding 73 and the normal conducting lead-shaped winding 74 in the magnetic flux flow state. The torque characteristic at this time is shown by phase F3 in FIG.

  That is, the superconducting rotating machine 1 has a torque characteristic as shown in FIG. 6, and operates in the induced torque main drive in the normal conducting state, and in the superconducting state, it operates in the synchronous torque main operation at the normal load and in the induced torque in the overload. Operates in the main drive.

<Superconducting rotating machine system>
FIG. 7 is a diagram showing a schematic configuration of a superconducting rotating machine system 100 incorporating the superconducting rotating machine 1 having the above-described configuration.

  The superconducting rotating machine system 100 mainly includes a superconducting rotating machine 1, a cooling device 11, a controller 12, an inverter 13, and a battery 14. The superconducting rotating machine 1 has a load 15 connected to the rotating shaft 75 thereof. For example, when the superconducting rotating machine 1 is mounted on a vehicle as an electric motor (motor) of an electric automobile, the load 15 is a wheel (drive wheel) connected via an axle.

  The cooling device 11 is provided in the refrigerant supply path 11a, the rotating shaft 75 and the rotor core 71 of the superconducting rotating machine 1, and the slot of the rotor 7 through an internal refrigerant supply path (not shown) communicating with the refrigerant supply path 11a. A refrigerant is supplied into 72. Thereby, the superconducting lead-shaped winding 73 provided in the superconducting rotating machine 1 is cooled below the critical temperature. As the refrigerant, helium gas, liquid nitrogen, or the like is used.

  The controller 12 controls the operation of the superconducting rotating machine 1 based on an external operation instruction given as the drive signal Sm. In addition, the cooling operation by the cooling device 11 is also controlled.

  As for the former, the controller 12 performs the superconducting rotation via the inverter 13 based on the primary current signal SI which is a signal of the primary current flowing through the stator winding 3b, which is continuously input from the superconducting rotating machine 1. The voltage V and the frequency f of the alternating voltage applied to the stator winding 3b of the machine 1 are controlled independently. Thereby, the rotational speed N and the torque τ of the superconducting rotating machine 1 are feedback-controlled.

  In a storage unit (not shown) of the controller 12, a control pattern for induction rotation used when the superconducting rotating machine 1 rotates with induced torque main rotation and a control pattern for synchronous rotation used when the superconducting rotating machine 1 rotates with synchronous torque main driving are used. Are stored in advance. The control pattern for induction rotation is the same as the known control pattern used for the conventional induction rotating machine. The synchronous rotation control pattern is the same as a known control pattern used for a conventional synchronous motor.

The controller 12 further stores a threshold value I _TH for the primary current signal SI. The threshold value I _TH is set in advance for each value of the ratio V / f between the voltage V applied to the stator winding 3b and its frequency f. Note that V / f is a value proportional to the amount of flux linkage to the superconducting lead-shaped winding 73 and further proportional to the torque applied to the superconducting lead-shaped winding 73.

Specifically, the threshold value I _TH is based on the value of the primary current signal SI in the superconducting state when the superconducting rotating machine 1 is actually operated to shift from the normal conducting state to the superconducting state. Is set. Setting as a 90% value is a preferred example.

The threshold value I _TH is used when the controller 12 determines whether or not the operation of the superconducting rotating machine 1 is synchronous torque main movement and determines a control pattern to be applied. That is, if the value of the primary current signal SI is smaller than the threshold value I _TH , the controller 12 determines that the superconducting rotating machine 1 is operating in the synchronous torque main drive, and applies the synchronous rotation control pattern. The superconducting rotating machine 1 is controlled. If the value of the primary current signal SI is equal to or greater than the threshold value I _TH, it is determined that the superconducting rotating machine 1 is operating with induced torque main motion and the superconducting rotating machine 1 is controlled by applying a control pattern for induced rotation. To do.

<Stable control during synchronous rotation>
Next, stable control when the superconducting rotating machine 1 is operated in the synchronous rotation of the synchronous torque main drive in the superconducting rotating machine system 100 will be described.

  FIG. 8 is a diagram showing the current-voltage characteristics of the superconducting lead-shaped winding 73 of the superconducting rotating machine 1. In FIG. 8 and the following description, the current I and the voltage V of the superconducting cage winding 73 itself are distinguished by adding a subscript s. As shown in FIG. 8, the current-voltage characteristics of the superconducting lead-shaped winding 73 follow a straight line La when 0 ≦ Vs ≦ V1, and follow a curve Lb when Vs> V1. However, V1 is a voltage value which becomes Is = Ic (critical current).

  Ideally, the current-voltage characteristics of the superconducting lead-shaped winding 73 should follow only the current-voltage characteristics of the superconducting material (bismuth-based high-temperature superconducting material) itself, which is a constituent material thereof. A normal conducting material (conductor) such as solder for joining the rotor bar 73a and the end ring 73b is slightly interposed in the conduction path 73. Therefore, even if the superconducting material of the superconducting lead-shaped winding 73 is in a superconducting state, the superconducting lead-shaped winding 73 as a whole has a finite resistance because the resistance of the normal conducting material cannot be ignored. The current-voltage characteristic of the superconducting lead-shaped winding 73 in this case follows Ohm's law, and this corresponds to the straight line La. Specifically, the straight line La is expressed by the following equation (1).

Vs = R · Is (1)
Here, the resistance value R is a constant determined by the material of the normal conducting material interposed in the superconducting lead-shaped winding 73 and the usage mode (for example, usage amount, usage area, etc.), and is also a value representing the slope of the straight line La. Although 0 ≦ R ≦ about 10 mΩ, R = 0 may be used when the resistance of the normal conductive material can be virtually ignored.

  On the other hand, when a current exceeding the critical current Ic flows through the superconducting lead-shaped winding 73, the superconducting lead-shaped winding 73 enters a loss state (a magnetic flux flow state in which loss occurs while being in the superconducting state), and the superconducting material itself Resistance (nonlinear resistance) is generated. A curve Lc represents this state. However, strictly speaking, the current-voltage characteristic of the superconducting lead-shaped winding 73 is represented by a curve Lb obtained by superimposing the straight line La and the curve Lc. As the current value increases, the current-voltage characteristics of the superconducting material itself become dominant in the superconducting cage winding 73 as a whole. The curve Lc is expressed by the following equation (2), for example.

Vs = Vc (Is−Ic) ⁿ (2)
Vc is a constant. Further, n is a value determined according to the superconducting material used for the superconducting lead-shaped winding 73, and n> 1. In this case, in FIG. 8, the slope of a straight line connecting an arbitrary data point (I, V) on the curve Lb and the origin is the resistance value Rr for the data point. The resistance value Rr of the superconducting lead-shaped winding 73 is a function of Is and Vs. As is clear from FIG. 8, the resistance value Rr in this case is equal to or greater than the resistance value R in the case of following the straight line La. That is, the superconducting material has a non-linear resistance in the range of the curve Lb. In the present embodiment, stable control of synchronous rotation of the superconducting rotating machine 1 is realized using such a nonlinear resistance.

  Schematically speaking, during the steady operation, the applied voltage V to the stator winding 3b and its frequency f so that the superconducting lead-shaped winding 73 satisfies the current-voltage characteristic represented by the straight line La in FIG. Are controlled independently. On the other hand, when the operation at the synchronous rotation is likely to become unstable, such as at the time of variable speed, the superconducting lead-shaped winding 73 is intentionally and instantaneously brought into a magnetic flux flow state satisfying the range of the curve Lb in FIG. The rotor 7 is once realized in the rotational state by the induced torque main drive, and then shifted to the synchronous rotation at the desired rotational speed, so that the stability of the synchronous rotational operation is maintained.

  As an example, based on the current-voltage characteristic represented by the straight line La in FIG. 8, the motor rotates at a first synchronous rotational speed corresponding to a preset ratio of the applied voltage V to the stator winding 3b and its frequency f. When the variable speed is changed from a state where the child 7 is rotating synchronously (a state where the first torque is applied) to a state where the child 7 is rotated synchronously at the second synchronous rotation number (a state where the second torque is applied). Think.

  First, when the rotor 7 is rotating synchronously at the first synchronous rotational speed, the state of phase F2 in FIG. 6 is realized. At this time, the superconducting lead-shaped winding 73 captures the interlinkage magnetic flux and satisfies the range of the straight line La in FIG.

  In this state, when given as a drive signal Sm for executing the variable speed from the outside, the controller 12 immediately changes the voltage V applied to the stator winding 3b and its frequency f, The ratio V / f is once increased until the current flowing through the superconducting lead-shaped winding 73 exceeds the critical current.

  When a current exceeding the critical current flows through the superconducting lead-shaped winding 73, the superconducting lead-shaped winding 73 enters a magnetic flux flow state satisfying the current-voltage characteristics represented by the curve Lb in FIG. At this time, a resistance value Rr sufficiently larger than the resistance value R in the superconducting state is generated in the superconducting cage winding 73. Thereby, the state of phase F3 in FIG. 6 is realized, and the rotor 7 once rotates by induced torque main movement.

  When the rotor 7 starts to rotate by the induced torque main drive, the controller 12 applies the voltage to the stator winding 3b so that the ratio V / f becomes a value corresponding to the second synchronous rotational speed instructed from the outside. The voltage V and its frequency f are changed. Along with this, the number of rotations of the rotor 7 changes, and soon the relative speed between the rotor 7 and the rotating magnetic field created by the stator 3 decreases. At the same time, the current flowing through the superconducting lead-shaped winding 73 also becomes smaller and becomes lower than the critical current. Then, the superconducting lead-shaped winding 73 captures the interlinkage magnetic flux, and the state of phase F2 in FIG. 6 is realized again. Thereafter, the rotor 7 is stably rotated by the synchronous torque main drive at the second synchronous rotational speed.

  By performing the control as described above, the superconducting rotating machine 1 has been able to shift from the state of synchronous rotation operation at the first synchronous rotational speed to the state of synchronous rotational operation at the second synchronous rotational speed. . Moreover, the rotating operation of the rotor 7 does not become unstable during the transition. In addition, the actual time required for the transition is, for example, about ten seconds at the maximum in the case of an automobile. In other words, when viewed from the duration of the driving operation assumed for the superconducting rotating machine 1 (at least several minutes), the operation in the induced torque main motion is instantaneous, and the synchronous operation is substantially stable. It is safe to say that it is maintained.

  That is, during synchronous rotation at a certain synchronous rotational speed, the applied voltage V to the stator winding 3b and its frequency f are changed so that the value of the ratio V / f once increases, and the induced torque If the applied voltage V and its frequency f are changed so that the ratio V / f becomes a value corresponding to the new synchronous rotational speed after the main rotation is generated, the synchronization at the new synchronous rotational speed is achieved. Smooth transition to rotation.

  The control according to the above aspect can be applied to any variable speed during synchronous rotation. In addition, the same control can be applied when the second synchronous rotational speed is the same as the first synchronous rotational speed. This means that the above-described control can be applied in general during synchronous rotation.

  Specifically, the controller 12 once sets the value of the ratio V / f once the synchronous rotation of the rotor 7 is likely to become unstable while the superconducting rotating machine 1 is performing synchronous rotation operation at a certain synchronous rotation number. The ratio V / f is again set to a value that gives the original synchronous rotation speed after increasing and shifting to rotation with induced torque main rotation. Note that the controller 12 can detect that the rotation of the rotor 7 has become unstable based on changes in the values of the rotational speed N, torque τ, and primary current signal SI.

  As described above, according to the present embodiment, by controlling the voltage applied to the stator winding and its frequency, the rotational operation in the induced torque main motion in the magnetic flux flow state is instantaneously used. Thus, it is possible to stably continue the rotation operation of the superconducting rotating machine with the synchronous torque main drive, including the case where the variable speed is performed. That is, the superconducting rotating machine can be operated independently and stably.

  Note that the current-voltage characteristics in the range of the straight line La in FIG. 8 are not different from the current-voltage characteristics of a conventional cage induction machine made of a normal conducting material, so that the synchronous rotation is stable within the range of the straight line La. It is difficult to make it happen. That is, in the case of performing a variable speed for shifting the rotor 7 from a state where it is rotated at a certain synchronous rotational speed to a state where it is rotated at another synchronous rotational speed, the desired synchronous rotation directly with the ratio V / f is directly achieved. Even if the value is set according to the number, the resistance value R in the superconducting lead-shaped winding 73 remains small, so that it is difficult to stably shift to the rotation at the new rotation number.

<Example of analysis by simulation>
In order to show that the above-described stable control is necessary and that such stable control is feasible, an analysis by simulation was performed. The results will be described below.

  In the simulation, the superconducting rotating machine 1 is assumed to be a three-phase four-pole squirrel-cage induction machine. The superconducting lead-shaped winding 73 was made of DI-BSCCO (registered trademark) wire. The stator winding 3b is an existing 8/9 distributed short-pitch copper winding. The operating temperature was 77K and the synchronous maximum output was 1.5 kW.

For the analysis, Matlab (registered trademark) / Simulink (registered trademark) was used. At that time, in addition to the equations (1) and (2), voltage equations and dynamic equations described later were applied. In the formula (1), R = 1 × 10 ⁻⁵ Ω. In the formula (2), n = 23.05. The effect of current shunting on the silver sheath material was also considered.

  FIG. 9 is a diagram comparing the analysis result with the actual measurement value for the no-load characteristic and the load characteristic of the superconducting rotating machine 1. FIG. 9A shows no-load characteristics, and FIG. 9B shows load characteristics (torque characteristics). In FIG. 9A, the horizontal axis input voltage V is the voltage applied to the stator winding 3b, and the vertical axis is the rotation speed of the rotor 7. 9A and 9B, the analysis results agree well with the actual measurement values. This means that the analysis conditions used for the simulation are appropriate.

  FIG. 10 is a diagram illustrating an analysis result on the stability limit of the synchronous rotation of the superconducting rotating machine 1. The input voltage on the horizontal axis is the voltage applied to the stator winding 3b, and the vertical axis is the rotation speed of the rotor 7. The result is for no load condition. In the figure, a broken line L1 connecting square marks (□ marks) indicates the stability limit of the superconducting rotating machine 1. Moreover, the broken line L2 which connected the round mark (circle mark) is the stability limit of the conventional cage induction machine shown for comparison. In FIG. 10, a region having a rotational speed equal to or higher than the stability limit is a region (stable region) in which stable synchronous rotation is realized.

  As shown in FIG. 10, the superconducting rotating machine 1 has a very narrow stable region as compared with the conventional cage induction machine. Incidentally, in the conventional squirrel-cage induction machine, since the magnetic flux in the iron core is saturated at the solid line L3 in the figure, all realistic operation regions are included in the stable region. Therefore, it is shown that the stable region of the superconducting rotating machine 1 is narrower than the practical operation region of the conventional squirrel-cage induction machine. Such a result indicates that when the superconducting rotating machine 1 is rotated synchronously, control for stabilizing it is necessary.

  FIG. 11 and FIG. 12 are diagrams showing the results of analyzing the stability of synchronous rotation at no load for two cases with different values of the ratio V / f. Specifically, both the frequency f was 60 Hz, and the applied voltage V was two levels of 40V and 50V. In both cases, the target synchronous rotational speed was set to 1800 rpm, and changes from the rotational speed of 0 were analyzed.

  FIG. 11 is a diagram showing an analysis result when the applied voltage V is set to 40V, and FIG. 12 is a diagram showing an analysis result when the applied voltage V is set to 50V. In either case, the horizontal axis represents time (unit: second), and the vertical axis represents the rotational speed N, torque τ, current I2 (= Is) flowing through the superconducting lead-shaped winding 73, and resistance value Rr.

  When the applied voltage V shown in FIG. 11 is 40V, the synchronous rotation speed does not reach the set 1800 rpm and remains at about 110 rpm, whereas when the applied voltage V shown in FIG. The synchronous rotation speed has reached 1800 rpm as set. In addition, after the rotation speed becomes constant, the torque τ, the current I2, and the resistance value Rr are also kept constant.

  The result shows that for the applied voltage V, there is a threshold value (corresponding to V1 in FIG. 8) between 40V and 50V where the rotation of the rotor 7 transitions from an unstable state to a stable state. Yes. Thereby, it can be said that the stable control of the synchronous rotation using the rotation by the induced torque main motion described above is actually realizable.

<Mathematical formula used for analysis>
The mathematical formulas used for the above analysis are listed below.

<Modification>
In the above-described embodiment, the rotor bar 74a of the normal conducting lead-shaped winding 74 is disposed outside the rotor bar 73a of the superconducting guide-shaped winding 73. However, in the present invention, the rotor bar 73a May be arranged outside the rotor bar 74a.

  Moreover, although the superconducting rotating machine 1 is configured to include the superconducting lead-shaped winding 73 and the normal conducting lead-shaped winding 74, in the present invention, the aspect including the normal conducting lead-shaped winding 74 is not essential. An embodiment having only the superconducting lead-shaped winding 73 may be used.

  Moreover, in the above-mentioned embodiment, although the superconducting rotating machine 1 having a configuration in which the stator 3 is provided on the outer periphery of the columnar rotor 7 is described, the present invention has the stator centered on the axis. The present invention can also be applied to a so-called outer rotor type superconducting rotating machine which is disposed at a position and has a cylindrical rotor rotating on the outer periphery thereof.

DESCRIPTION OF SYMBOLS 1 Superconducting rotating machine 3 Stator 3a Stator iron core 3b Stator winding 4a, 4b Bracket 7 Rotor 71 Rotor iron core 72 Slot 73 Superconducting cage winding 74 Normal conducting rod winding 100 Superconducting rotating machine system

Claims (4)

A method of operating a superconducting rotating machine comprising a rotor having a superconducting lead-shaped winding in which a rotor bar and an end ring are constituted by a superconducting wire,
The rotation state of the rotor is changed from the first rotation state of the first torque and the first rotation number to the second torque and the second rotation that are the same as or different from the first torque and the first rotation number. The superconducting of the rotor in the first rotating state is controlled by controlling the voltage applied to the primary winding of the superconducting rotating machine and its frequency when shifting to the second rotating state of Once the squirrel-cage winding is in a magnetic flux flow state, it is shifted to the second rotation state.
A method for operating a superconducting rotating machine. A method of operating the superconducting rotating machine according to claim 1,
The magnetic flux flow state is realized by increasing the ratio between the applied voltage and the frequency so that a current higher than the critical current flows through the superconducting cage winding,
When the magnetic flux flow state is realized, a ratio between the applied voltage and the frequency is set to a value according to the second rotation state.
A method for operating a superconducting rotating machine. A superconducting rotating machine including a rotor having a superconducting lead-shaped winding in which a rotor bar and an end ring are constituted by a superconducting wire, and a stator including a primary winding;
A controller for controlling the operation of the superconducting rotating machine;
A superconducting rotating machine system comprising:
The rotation state of the rotor is changed from the first rotation state of the first torque and the first rotation number to the second torque and the second rotation that are the same as or different from the first torque and the first rotation number. When the state is shifted to the second rotational state, the controller controls the voltage applied to the primary winding and the frequency thereof, whereby the superconductivity of the rotor in the first rotational state is controlled. Once the squirrel-cage winding is in a magnetic flux flow state, it is shifted to the second rotation state.
A superconducting rotating machine system. The superconducting rotating machine system according to claim 3,
The controller is
The magnetic flux flow state is realized by increasing the ratio between the applied voltage and the frequency so that a current higher than the critical current flows through the superconducting cage winding,
When the magnetic flux flow state is realized, a ratio between the applied voltage and the frequency is set to a value according to the second rotation state.
A superconducting rotating machine system.

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