JPH0792509B2 - Excitation method for multiple magnetically coupled superconducting coils - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of exciting a superconducting coil used in a magnetic field generator of a magnetic confinement type fusion device.

[0002]

2. Description of the Related Art Recently, large-scale superconducting coils have come to be used in magnetic field generators for generating a stationary magnetic field, such as helical type fusion devices and cusp type fusion devices. This type of magnetic field generator uses several superconducting coils, each requiring different currents, which are often magnetically coupled to each other. Moreover, the current is a few
It had become a large current of several tens of kA. Conventionally, in the exciting circuit of a plurality of superconducting coils, excitation is performed by the same number of power sources as the current circuits flowing in the superconducting coils.

[0003]

In such a stationary magnetic field generator, a stationary magnetic field which does not change with time is required, and the power supply generates a required voltage when the current is raised to a required current. The voltage required to maintain that current is zero at the coil terminals. Therefore, basically no power supply is required to maintain the current. That is, it is well known that the current of the coil can be maintained by short-circuiting both ends of the coil, and it is well known as a permanent current. When there is no magnetic coupling, multiple superconducting coils are sequentially operated by a single power source. It is easy to excite with a permanent current. However, in the case of multiple permanent current superconducting coils that are magnetically coupled, if a power source is connected to one coil and the coil current is changed to another value, the currents of other coils also change. Therefore, there is a problem that the current of the coil cannot be independently set.

In the stationary magnetic field generator having a plurality of magnetically coupled superconducting coils as described above, the current of each current circuit can be controlled by using only one power source without using many expensive large current power sources. What could be set arbitrarily was desired.

The present invention has been made to solve the above problems, and an object of the present invention is to excite a plurality of magnetically coupled superconducting coils with a single power source, and all the coils. An object of the present invention is to provide a method for exciting a superconducting circuit that can set the current to an arbitrary value.

[0006]

In order to achieve the above object, in a method of exciting a superconducting circuit according to the present invention, a plurality of magnetically coupled superconducting coils and respective short-circuit switches provided between respective terminals thereof, It consists of one bipolar variable voltage power supply,
When exciting the exciting circuit connecting each of the above terminals and the bipolar variable voltage power supply via the connection switch respectively, based on the final current value determined from the mutual induction coefficient matrix of these multiple coils and the order of excitation. , The order of excitation of each coil and the initial current value for obtaining the desired final current value are determined, and the connection switch of the first superconducting circuit is closed according to this order to generate a voltage in the bipolar variable voltage power supply. ,
After the predetermined initial coil current is reached, the short-circuit switch is closed and the connection switch is opened to bring this superconducting coil into a quasi-permanent current state. Excited by the current,
It is characterized in that all of the superconducting coils are brought into a quasi-permanent current state of a desired current value by making them into a quasi-permanent current state.

[0007]

Operation: The connection switch connecting the first superconducting coil and the bipolar variable voltage power supply is closed, and then the voltage of the bipolar variable voltage power supply is generated to increase the current of the superconducting coil. The initial current value for the first coil is raised, and thereafter, the voltage is set to hold the current of the superconducting coil. In this state, when the short-circuit switch connected to the terminal of the superconducting coil is closed, the voltage of the power source is generated in the opposite polarity, and when the current flowing from the power source disappears, the connection switch is turned off. Open circuit. In this state, the current of the first superconducting coil is a quasi-permanent current through the short circuit switch.

Next, the connection switch connecting the second superconducting coil and the bipolar variable voltage power supply is closed, then the voltage of the power supply is generated, and the current of the superconducting coil is increased to increase the second current. The initial current value for the coil is raised, and thereafter, the voltage is set to hold the current of the superconducting coil.
In this state, after closing the short-circuit switch connected to the terminal of the second superconducting coil, the voltage of the power source is generated in the opposite polarity and the current flowing from the power source is almost eliminated. Open the switch. In this state,
The current of the second superconducting coil is a quasi-permanent current through the short-circuit switch. At this time, the first coil current is the second
Due to the magnetic coupling with the coil, the quasi-permanent current has a value different from the initial initial current for the first coil.

In the same manner, when the superconducting coils are excited one after another and the excitation of all the superconducting coils is completed, a quasi-permanent current flows in each coil. However, the value of the quasi-permanent current of each coil is a final value which is sequentially changed each time the coil is newly excited due to magnetic coupling.

The final quasi-permanent current value of each coil is uniquely determined by the mutual induction coefficient indicating the degree of magnetic coupling between the coils, the initial current value of each coil, and the order of excitation. Therefore, it is possible to pre-calculate the excitation sequence and the initial current value of each coil so that the final quasi-permanent current values of all the coils will be the desired values. Permanent current value can be set.

Next, the following procedure is performed to demagnetize all the coils. An arbitrary coil is selected, the connection switch connected to it is closed, and the same current as that flowing in the coil is supplied from the power supply. In this state, the short-circuiting switch has no current, so the short-circuiting switch is opened. Next, if a voltage is generated in the power supply in the direction of decreasing the current, the connection switch is opened when the current decreases to substantially zero. Similarly, the coils can be demagnetized one after another to eliminate the current in all the coils.

During the demagnetization of all the coils, it is possible to excite the unexcited coils if necessary. By setting another initial current, another final quasi-permanent current value combination can be obtained.

When the coils are sequentially excited, the current of a certain coil may exceed the maximum current value allowed for the coil. In such a case, it can be avoided by changing the order of excitation.

In this way, it is possible to excite a plurality of superconducting coils at arbitrary current values with only one power source.

The quasi-permanent current in the above description will be described. Although the above-mentioned short-circuit switch is a normal conduction switch, it is kept in mind that an electric resistance thereof is extremely small. That is, the ratio L / R of the self-induction coefficient L of the superconducting coil connected to it and the total resistance R of the short-circuit switch including the connection resistance with the terminal of the superconducting coil.
Is called the decay time constant, and if this magnitude (time) is sufficiently long compared to the length of time that is regarded as "steady" as the usage time of the excitation, demagnetization, and steady magnetic field generator, the current of this circuit is It is called quasi-permanent current because it can be regarded as a permanent current. That is, in this case, it may be considered that the current does not decay during the use time of the stationary magnetic field generator.

In the current technology, the superconducting large-current short-circuit switch that can be used for the magnetic field generator of the large-scale fusion device has not been developed yet, so that the short-circuit switch must use the normal conduction switch. However, if a superconducting switch that can withstand high voltage and large current is developed,
It can be used for truly permanent current.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 1 is a superconducting coil for a helical magnetic field, in which three coils are connected in series.
3 is the terminal. 4, 5, 6 are superconducting coils for poloidal magnetic field, 7, 8 are terminals of the superconducting coil 4, 9,
Reference numeral 10 is a terminal of the superconducting coil 5, and 11 and 12 are terminals of the superconducting coil 6. Reference numeral 13 is a thyristor rectifying power source as a bipolar variable voltage power source, which can generate positive and negative voltages and can change its magnitude according to a command from a control device (not shown). 14 is a short circuit switch inserted between the terminals 2 and 3, and 15 is a terminal 7.
Is a short circuit switch inserted between the terminals 9 and 10, 16 is a short circuit switch inserted between the terminals 9 and 10, and 17 is a short circuit switch inserted between the terminals 11 and 12.

Reference numeral 18 denotes a bipolar variable voltage power supply 13 for terminals 2 and
3 is a connection switch inserted so as to be connectable to 3; 19 is a connection switch inserted so that the bipolar variable voltage power supply 13 can be connected to the terminals 7 and 8; 20 is a bipolar variable voltage power supply 13; A connection switch inserted so as to be connectable to 10, a reference numeral 21 denotes a bipolar variable voltage power supply 13, a terminal 11,
12 is a connection switch inserted so that it can be connected to 12. Each of the short circuit switches 14 to 17 and the connection switches 18 to 21 is provided with a driving means such as electric, hydraulic and pneumatic pressure,
A control device (not shown) can open and close them.

The superconducting coils 1 to 6 and the bipolar variable voltage power supply 13 are equipped with current measuring devices for measuring the respective currents so that the measured current values are transmitted to the control device. . Further, the control device generates the voltage of the bipolar variable voltage power supply 13 so that each of the coil currents has a preset current value, or compares the coil current and the bipolar variable voltage power supply 13 with each other. Then, when they substantially match, the short-circuit switch connected to the coil is opened, or when the current value of the bipolar variable voltage power supply 13 becomes substantially zero, the closed connection switch is opened. It has a function.

Superconducting coils for the above three helical magnetic fields, three superconducting coils for the poloidal magnetic fields 4, 5, 6
Are magnetically coupled to each other. Further, the direction of the current of the superconducting coil is set so that only the superconducting coil 4 is reversed.

Next, the operation will be described with reference to FIGS. First, the excitation method will be described. The connection switch 18 is closed, and the bipolar variable voltage power supply 13 (hereinafter abbreviated as power supply).
Generate more voltage. After the current of the superconducting coil 1 increases to reach the initial current value I ₁₁ , the current value is maintained. After closing the short-circuiting switch 14, if the voltage of the power supply is made negative, the power supply current decreases and becomes substantially zero, and then this voltage is held. After this, the connection switch 18 is opened. At this time, the current of the superconducting coil 1 flows through the short circuit switch 14 and becomes a quasi-permanent current.

Next, the connection switch 19 is closed to generate a voltage from the power supply. After the current of the superconducting coil 4 increases and reaches the initial current value I ₂₁ , the current value is maintained. After closing the short-circuiting switch 15, if the voltage of the power supply is made negative, the power supply current decreases and becomes substantially zero, and then this voltage is held. After this, the connection switch 19 is opened. At this time, the current of the superconducting coil 4 flows through the short circuit switch 15 and becomes a quasi-permanent current. At this time, the current of the superconducting coil 1 has changed to I ₁₂ .

Similarly, the superconducting coil 5 is excited to have an initial current value I ₃₁ and the superconducting coil 6 is excited to have an initial current value I ₄₁ . In this state, the quasi-permanent current of superconducting coil 1 is I ₁₄ , the quasi-permanent current of superconducting coil 4 is I ₂₃ , and the quasi-permanent current of superconducting coil 5 is I _32. There is.

Quasi-permanent current value I at this time₁₄, I_{twenty three}, I₃₂，
I₄₁And the initial current value I₁₁, I_{twenty one}, I ₃₁And on the way semi-permanent
Current value I₁₂, I₁₃, I_{twenty two}The relationship between the
Since the induction coefficient matrix is known in advance, it can be easily calculated.
You can Therefore, the required final permanent current will be obtained.
If the initial current value is calculated in advance, the final value can be easily obtained.
You can

By thus supplying the quasi-permanent current required for the superconducting coil, it is possible to carry out a fusion experiment using the quasi-stationary magnetic field produced by the quasi-permanent magnetic field.

In the above excitation sequence, the superconducting coil 1
The quasi-permanent current I ₁₂ is larger than the final quasi-permanent current I ₁₄ . If I ₁₂ exceeds the maximum allowable current value of the superconducting coil 1, it is possible to change the order of excitation and select an order not to exceed. For example, the superconducting coil 1 may be excited last. Since the four superconducting coils are excited in 24 ways, it is possible to find an appropriate order among them.

Next, the demagnetization method will be described. Demagnetize by following the exact reverse sequence of excitation. That is, the connection switch 21 is closed to generate a voltage in the power supply and match the power supply current with the current I41 of the superconducting coil 6. At this time, the current of the short circuit switch 17 becomes zero and the short circuit switch 17 is opened. After that, when a negative voltage is generated in the power source, the current in the superconducting coil 6 decreases to zero, and the connection switch 21 is opened at this point. In this way, it is possible to demagnetize the superconducting coils 5, 6, 4, 1. The order of demagnetization may start from any superconducting coil, and there are 24 orders.

In the case where the time constant of the quasi-permanent current is not sufficiently long, when the set current value decreases, it is necessary to set the current value again. In this case, the demagnetization method and the excitation method described above may be successively performed.

In the above-mentioned embodiment, all the superconducting coils provided in the nuclear fusion device are excited by one power source, but the present invention can be applied to some plural superconducting coils. Is. If you want a superconducting coil whose current does not change while changing the current of other superconducting coils,
This is possible if a power source dedicated to this superconducting coil is provided.

[0030]

According to the present invention, a plurality of magnetically coupled superconducting coils, each short-circuit switch provided between each terminal thereof, and one bipolar variable voltage power source are provided, and each of the above-mentioned terminals is provided. When exciting the excitation circuit that connects each of the above and the bipolar variable voltage power supply via the connection switch, based on the final induction current value determined from the mutual induction coefficient matrix of these multiple coils and the order of excitation, the desired final The order of excitation of each coil for obtaining the current value and the initial current value are determined, and in accordance with this order, the connection switch of the first superconducting circuit is closed to generate a voltage in the bipolar variable voltage power supply, and the predetermined voltage is set. After reaching the initial coil current, the short-circuit switch is closed and the connection switch is opened to bring this superconducting coil into a quasi-permanent current state. And exciting the coil current, since such a respective semi-permanent current state, only one power supply,
A quasi-permanent current having a desired current value can be passed through all superconducting coils.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a waveform diagram showing a current change in each superconducting coil during excitation.

[Explanation of symbols]

 1, 4, 5, 6 Superconducting coil 13 Bipolar variable voltage power supply 14, 15, 16, 17 Short-circuit switch 18, 19, 20, 21 Connection switch

Claims (1)

[Claims] 1. A plurality of magnetically coupled superconducting coils, respective short-circuit switches provided between respective terminals thereof, and one bipolar variable voltage power supply, wherein each of the terminals and the bipolar variable voltage are provided. When exciting the excitation circuit that is connected to the power supply via the connection switch respectively, based on the final current value determined from the mutual induction coefficient matrix of these multiple coils and the order of excitation, to obtain the desired final current value The order of excitation of each coil and the initial current value are determined, the connection switch of the first superconducting circuit is closed according to this order to generate a voltage in the bipolar variable voltage power supply, and the predetermined initial coil current is reached. After that, the short-circuit switch is closed and the connection switch is opened to bring this superconducting coil into a quasi-permanent current state. Then, each superconducting coil is brought into a quasi-permanent current state to bring all the superconducting coils into a quasi-permanent current state of a desired current value.