JPH0744103B2 - Excitation device for superconducting coil - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting coil excitation device for demagnetizing a coil of a superconducting pulse magnet.

2. Description of the Related Art Since a superconducting coil has a resistance value of 0, it can pass a current without being attenuated. Therefore, excitation with a fast rise is easy, and it is effective as a means for instantaneously obtaining a strong magnetic field. Development of magnetic field generators and power storage systems for sealing high-temperature plasma in fusion reactors inside the reactor is underway.

FIG. 3 is a block schematic diagram of a conventional superconducting coil exciter.

In FIG. 3, 1 is a superconducting coil, 2 is a resistor, 3 is a switch, 4 is a power source for supplying an exciting current to the superconducting coil 1, and 5 is a current detection for detecting the value of the current flowing through the superconducting coil 1. It has a current-voltage conversion gain of Ka [V / A]. Reference numeral 6 is a command generating means for generating a current value to be passed through the superconducting coil 1, and 7 is power supply controlling means for controlling the power supply 3 in accordance with the difference between the output of the command generating means and the output of the current detecting means 4. The transfer function F (s) is F
(S) = K ₁ · (s + b) / (s + a). here,
s is a Laplace operator. Reference numeral 8 is a quench detecting means for detecting that the superconducting coil 1 is quenched due to a temperature rise, an external magnetic field, or the like, that is, the superconducting state is broken and the resistance value starts.

The operation of the conventional superconducting coil exciting device configured as described above will be described in more detail.

In the excitation mode of the superconducting coil, the switch 3 is closed, and the command generating means 6 generates a step-shaped target current value. The power supply control means 7 outputs a control voltage signal according to this target current value, and the power supply 4 applies a voltage to the superconducting coil 1. Along with this, the current detecting means 5 detects the value of the current flowing through the superconducting coil 1 and forms a negative feedback loop so that it matches the target current value.

The voltage-to-current transfer characteristic of the superconducting coil has a perfect integral characteristic 1 / (Ls) due to only the inductance component of the coil because the resistance value is 0. Therefore, when the exciting current of the superconducting coil reaches the target value, the voltage supplied by the power supply 4 is held. The voltage at this time is 0. Such a state in which a constant current flows at a voltage of 0 is called a permanent current state.

In this permanent current state, when the superconducting coil 1 is quenched, the permanent current causes the superconducting coil 1 to abnormally heat due to Joule loss, and in the worst case, burns or burns out. The quench detecting means 8 detects that the superconducting coil 1 has started to have a resistance value by using a bridge circuit or the like, and opens the switch 3. As a result, the exciting current is rapidly attenuated in the resistor 2 and the burnout of the superconducting coil 1 is prevented. (For example,
SUMMARY OF THE INVENTION Problems to be Solved by the Invention However, the above-described superconducting coil exciter has the following problems.

The load impedance of the power source 4 including the resistor 2 is (R + s
L) / (sRL). Here, R is the resistance value of the resistor 2.

At this time, the closed-loop transmission relationship G (s) of the above-described superconducting coil exciter is given by the following equation.

Given in. However, A = (a + GL) / R / (R + G)
+ B · G / (R + G) and B = G · b / L · R / (R + G). Where L is the inductance of the superconducting coil 1, G ₀
= Ka · K ₁ .

FIG. 4 is a waveform diagram showing the unit step response of G (s), and the response value is standardized by the target value. Figure 4 (a)
As shown in, since the denominator of the equation (1) has a second-order lag form, it may overshoot the target value.
Due to this overson-yout, there is a problem that the critical current of the superconducting coil is exceeded and it is easy for wrench. Further, in order to suppress this overshoot, if the braking of G (s) is increased as shown in FIG. 4B (that is, if the denominator is factorizable), the convergence time to the target value becomes longer. There is a problem.

In other words, the braking of the control system and the rising time are in a relationship of front and back, and are not compatible. This is because in a system with large braking, it is necessary to increase the response frequency of the system in order to accelerate the rise time, and for this purpose, it is necessary to increase the gain K _{1 of the} controller. This is because when the gain of the controller is increased, there is a problem that it may malfunction due to noise or that it may not operate as designed due to the limitation of the operating range of the controller.

Means for Solving the Problems In order to solve the above problems, the superconducting coil exciting device of the present invention is a superconducting coil, a power supply for supplying voltage and current to the superconducting coil, and a current flowing through the superconducting coil. Current detecting means for detecting the amount, command generating means for outputting the first target value and the second target value, and substantially any one of the first target value and the second target value. That the output value of the current detection means has reached the second target value, the power supply control means for controlling the power supply according to the difference between the output of the switching means and the output of the current detection means. And a switching control means for controlling the switching means.

Action According to the present invention, since the superconducting coil is excited with the current value set to a value larger than the desired exciting current value as a target, the exciting time is shortened. Further, since the control target value of the power supply control means is switched to the original target value when the desired exciting current is reached, overshoot can be prevented, and therefore quenching due to this overshoot can be prevented. Becomes

Embodiment Hereinafter, a superconducting coil exciter according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic block diagram of an exciting device for a superconducting coil according to the present invention. 1 is a superconducting coil, 2 is a resistor, 3 is a first switch, 4 is a power supply, 5 is a current detection means, 7 is a power supply control means, 6 is a first target value and a second
Is a quench detecting means, 9 is a comparator for detecting that the output value of the current detecting means 6 has reached the second target value, and 10 is a second switch. is there. In FIG. 1, the superconducting coil 1, the resistor 2, the first switch 3, the power source 4, the current detecting means 5, the power source controlling means 7 and the quench detecting means 8 are the superconducting coil 1 and the resistor in the conventional example of FIG. 2, the switch 3, the power supply 4, the current detection means 5, the power supply control means 7, and the quench detection means 8 are the same, and therefore detailed description thereof is omitted here.

Now, the operation of the exciting device for the superconducting coil of the present invention configured as described above will be described in more detail. FIG. 2 is a signal waveform diagram showing operation waveforms of respective parts of the superconducting coil exciting device of the present invention, and FIGS. 2 (a) to 2 (d) show points A to D in FIG. Corresponding to.

First, the case of exciting the superconducting coil 1 will be described. Here, the desired exciting current value is I ₀ .

At this time, the first switch 3 is closed and the second switch 10 is connected to the α terminal side. Further, the command generating means 6 is configured to generate the step-like first target current signal A
X I ₀ , FIG. 2 (a)) and a second target current signal B (target value I ₀ , FIG. 2 (b)) are generated.

The power supply control means 7 outputs a control voltage signal in response to the target current signal A, and the power supply 4 applies a voltage to the superconducting coil 1. At the same time, the current detecting means 5 detects the value of the current flowing through the superconducting coil 1 and configures a negative feedback loop so that it matches the target current signal A. It rapidly rises with the dashed-dotted line in FIG. 2 (c) as the target.

The transfer function G '(s) of this negative feedback loop is Given in. However, A '= (a + G / L) R / (R +
G) + b ・ G / (R + G), B ′ = G ・ b / L ・ R / (R +
G). Therefore, it is the same as G (s) in the equation (1).

Now, when the exciting current C of the superconducting coil 1 (that is, the output C of the current detecting means 5) reaches I ₀ , the comparator 9
A switching signal D (Fig. 2 (d)) is output. In response to the switching signal D, the second switch 10 is connected to the β terminal side and switches the input of the power supply control means 7 to the second target value B. With this, since the target value has already been reached,
The exciting current of the superconducting coil 1 rapidly converges to the second target value B, and the current value I ₀ is maintained.

Here, by designing the values of a, b, and G so that the denominator of equation (2) has a real root, overshoot can be prevented.

Therefore, the excitation of the superconducting coil 1 can be speeded up, and the overshoot of the exciting current can be suppressed to be small. Furthermore, it is possible to prevent quenching of the superconducting coil 1 due to this overshoot.

Now, when the exciting current reaches a steady value, the quench detecting means 8 monitors the voltage across the superconducting coil 1 and the like. When the superconducting coil 1 is quenched, the quench detecting means 8 opens the first switch 3 so that the exciting current is consumed by the resistor 2 to prevent the superconducting coil 1 from burning or burning.

Further, when demagnetizing the superconducting coil 1, if the first target value A is -I ₀ and the target value B in FIG. 2 is 0, exactly the same operation can be performed.

In the above embodiment, the first target value and the second target value are generated separately, but the second target value may be attenuated to create the first target value, or the first target value may be generated. The target value may be amplified to create the second target value.

Further, although the resistor 2 has a structure which is always connected in parallel to the superconducting coil 1, it may be said that the resistor 2 is connected only at the time of quenching.

In addition, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the invention.

EFFECTS OF THE INVENTION As described above, according to the present invention, since the superconducting coil is demagnetized for a value larger than a desired value in the excitation / demagnetization of the superconducting coil, high-speed excitation / demagnetization is possible. . Moreover, since the desired current value is reset when the exciting current of the superconducting coil 1 reaches the target value, the transient overshoot of the exciting current can be suppressed to a small value. Therefore, it has an excellent characteristic that quenching due to overshoot of the exciting current of the superconducting coil can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of an exciting device for a superconducting coil according to the present invention, FIG. 2 is a signal waveform diagram of each part of the exciting device for a superconducting coil according to the present invention, and FIG. 3 is a schematic block diagram for an exciting device for a conventional superconducting coil. Figure 4 shows the transfer function G (s)
It is a waveform diagram of a unit step response of. 1 ... Superconducting coil, 4 ... Power supply, 5 ... Current detection means, 6 ... Command generation means, 7 ... Power supply control means, 9 ...
Comparator, 10 ... Second switch.

Claims (1)

[Claims] 1. A superconducting coil, a power supply for supplying a voltage and a current to the superconducting coil, a current detecting means for detecting the amount of current flowing through the superconducting coil, and a first target value and a second target value. Depending on the difference between the output of the command generating means for outputting, the switching means for substantially outputting either the first target value or the second target value, and the output of the current detecting means. Power supply control means for controlling the power supply, and switching control means for controlling the switching means by detecting that the output value of the current detection means has reached the second target value. Exciting device for superconducting coil.