JPS59132108A - Power supply device for superconductive coil - Google Patents

Abstract

PURPOSE:To prevent the influence and propagation of normal conductive displacement by keeping each parameter of a power supply device for a plurality of electromagnetically coupled superconducting coils in predetermined relationship. CONSTITUTION:When self-inductance of a plurality of superconducting coils is represented in L1, L2...Ln, No.k and No.i mutual inductance in Mki, excitation current values in I10, I20...In0, protective resistance values in R1, R2...Rn, rated inversion voltage of a DC power supply in [E1]INV..., a resistance value per unit length of a wire rod for the superconducting coil in r, weight in m, specific heat in c, the normal temperature of a superconducting wire in T0, an allowable upper-limit temperature in TF and the dielectric strength of the superconductive coil in EKO, these values satisfy the following formula. Accordingly, the influence and propagation of normal conduction displacement can be prevented.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a power supply device for a superconducting coil,
In particular, the present invention relates to a system comprising two or more superconducting coil groups having mutual inductance and a power supply group thereof.

[Technical background of the invention and its problems]

Superconducting coils are made of certain metals, alloys (e.g. NbTi
, Nb3Sn, etc.), the electrical resistance becomes zero at extremely low temperatures, to obtain a high magnetic field with low loss, and to apply it to nuclear fusion devices, accelerators, energy storage devices, etc. In recent years, high-performance superconducting wires have been developed.

Research and development of superconducting phenomena and technologies, such as advances in superconducting coil winding technology, have made remarkable progress, and large-sized, high-field, high-energy superconducting coils have been manufactured. Letting the current flowing through the superconducting coil be E and the self-inductance be L, the stored energy 2 - will be 2 LI . If a superconducting coil undergoes a normal conduction transition (quench) for some reason during operation, this energy becomes Joule heat inside the coil, destroying the coil.

To avoid this, it is common to insert a protective resistor for energy absorption between the coil and the power supply.
a) E shows this basic circuit. In order to excite the superconducting coil 1 (second, open the switch 3 (SW2),
Close switch 4 (SWI) and apply current ■ from DC power supply 5 (E).

When the superconducting coil 1 quenches, close the switch 3,
The switch 4 is opened to disconnect the power source 5, and the current is attenuated in the L-R closed circuit consisting of the superconducting coil 1 and the protective resistor 2. Assuming that the resistance of the quenched superconducting coil 1 is sufficiently small compared to the protective resistor 2, the current flow of the superconducting coil has an exponential relationship I = I(
, e-"4'...attenuates at (1). (However,
0 indicates the current value flowing through the superconducting coil l when the switch 4 was opened. Suru is the resistance value of the protective resistor 2, and -L is the self-inductance of the superconducting coil 1. )(L), in order to attenuate the current in the superconducting coil l as quickly as possible during quenching, the value R of the protective resistor 2 must be
The larger the (attenuation time constant τ=L/R), the higher the current
The minimum resistance required to attenuate is determined from the following conditions.

fγI'dt < 4. ”mcdT・・・・・・・・・
...(2) However, γ: resistance value per unit length of superconducting wire (including stabilizing material) m: weight per unit length of superconducting wire (including stabilizing material) C: superconducting wire ( Specific heat of the superconducting wire (stabilizing material included) (e.g. 100k) To: Initial temperature of the superconducting wire (stabilizing material containing) (e.g. 4.
2k) Substituting the equation ([) into the equation (2) and rearranging it, we get the equation (3).

R≧Keii/gu'÷dT・・・・・・・・・・・・(3) On the other hand,
If the voltage E applied between the terminals of the superconducting coil 1 is too high, the superconducting coil 1 will suffer dielectric breakdown, so there is an upper limit value for R. When a quench occurs, when the switch 2 is closed and the switch 1 is opened as described above, the voltage E generated between the terminals of the superconducting coil 1 is g=RI=)LI□ e- from equation (1).
: It becomes t. Therefore, it is necessary that the maximum value RIo of E is smaller than the dielectric strength Eo (for example, 1ooov) of the superconducting coil, and from this condition, the upper limit value is (4)
It is given by Eq.

Bo/Eng. ≧R01000000, (4) In the conventional superconducting coil power supply device, the protective resistance is expressed by the above formula (3), (4)
In order to attenuate the current quickly within the range that satisfies the equation (4), the upper limit value of the range that satisfies the equation (4) was selected.

Next, as shown in Fig. 2(a), two superconducting coils L
Consider the case where t and L2 are electromagnetically coupled by mutual inductance M. Superconducting coil L1. Excitation current 1 in L2
1゜l 'When IQ is flowing, superconducting coil L1
is quenched, 8W12 is closed, and 5W11 is opened. The current is 1 i, = I,. eτ ・・・・・・・・・・・・・・・
It is attenuated by (5), and the current in superconducting coil L2 is M t Ir I20+7Ito(l e-r ) −=−−
(It increases by 61. (See Figure 2 (b).) In other words, the current of the superconducting coil L2 is maximum ■, +π.
7), (for example, 11°"" 2
01 LI""M L, r Considering the case where M= 4 = 0.5, "2"
0 +1. , "10 = 15I2o, 150chi overcurrent.) There was an extremely high possibility that superconducting coil L2, which has not yet quenched, would be quenched. Also, the protection in case superconducting coil L2 is quenched is as described above. As in the case, 5w22 is closed, 5w21 is opened, and energy is consumed and protected using the protective resistor determined by the methods of equations (3) and (4) above.In other words, the conventional system uses one superconducting coil. It is simply a control and protection method that electromagnetically couples a simple system consisting of the It was the economy.

[■Target of invention]

In a system consisting of a plurality of electromagnetically coupled superconducting coils, when one superconducting coil quenches, the present invention quickly attenuates the current of that superconducting coil and quenches the other unquenched superconducting coils. An object of the present invention is to obtain a power supply device for a superconducting coil that prevents

Examples of the invention] The principle of the present invention will be explained below with reference to the drawings.

In the following explanation, for simplicity, a case will be considered in which there are two superconducting coils.

FIG. 2(a) In l1, the circuit equation when the superconducting coil L1 is quenched, 8W12 is closed, and 5W11 is open is as shown in formula (8).

Lll, + M I, + RIIt =O-10,
I force L2I, + MI, =g, ・・
(8) When the power source E is controlled so that the current in the superconducting coil L2 does not change (in other words, it is controlled so that the current is 0), the current in the superconducting coil L2 is The current will not change.

In the conventional system, the power supply E1. The output voltage of B is calculated from the coil excitation time T, excitation current, and coil self-inductance as follows:
Q KA , for T = 60 minutes E, -E, ==lQ
'X10X10'A/60X60sy28V) The power supply E,
The inverter voltage is designed to be (for example, L1=lOH,
M=58, R,=20mΩ.

When I + a = LOKA, "'JrNv = toov.) When superconducting coil L1 is quenched, power supply E2 is set to (1
The present invention provides a power supply device for a superconducting coil that makes it possible to reduce the current change in the superconducting coil L2 to zero and prevent the spread of quench by controlling as shown in Equation 01.

In the above explanation, we are concerned with the case where the superconducting coil Ll is quenched, but if we also consider the case where the superconducting coil L2 is quenched, the superconducting coil is composed of two electromagnetically coupled superconducting coils and their excitation power source. system (1)
If one superconducting coil quenches by determining the resistance value of the protective resistor and the rated inverter voltage of the excitation power source so as to satisfy the following relational expression, the current in that coil is quickly decayed, and the current in the other healthy superconducting coils is quenched. It is possible to provide a power supply device for a superelectric coil, which is characterized in that the coil is controlled at a constant current, prevents the spread of quench, and has an energy saving effect.

As is clear from equation (9), the values of the protective resistors LL and R2 are proportional to the inverter voltage of the DC power supplies EL and FJ2, so in order to make the power supply rational and inexpensive, the protective resistors R1 and R2 must be It is desirable to select the lower limit value within a range that satisfies equation (9).

Next, consider extending the above relationship to the case of a plurality of electromagnetically coupled superconducting coils. When the first superconducting coil in a group of n superconducting coils electromagnetically coupled is quenched and this coil is protected by the protective resistor Ri according to the method described above, the circuit equation is as follows.

If we assume that the currents of the superconducting coils other than the i-th superconducting coil are controlled at a constant current, I k = 0.1c = l~
n.

Since k ~ i (formula 1111 is becomes. Therefore, equation 01 is solved to obtain equation α2.

In other words, the coil of Hokome is quenched, and the protective resistance Ri
When the current is attenuated at (k=1 to n.

k to I) The inverter voltage of the coil power supply is maximum [E
J INV knee! ! If the k-th coil is designed to be able to output 5" output, the k-th coil can be controlled with a constant current. Here, in order to enable constant current control of the i-th coil even if any of the coils i = l to n, 凰 to ni is quenched, formula 131 should hold true.

Mkn　FjnIn.

Ln]・・・・・・・・・a3 However, the symbol Max[Xt + X! p −, Xn] is x11X! Indicates the maximum value among j...xm. For example, when x, ≦X, ≦...≦Xn, MaX(,
g g...HXn) "" Xfl.

Furthermore, by adding the constraint condition of the protective resistor to C%, and determining the resistance value Rk of the protective resistor of the power supply device of the th coil and the rated inverter voltage [Ek)INv of the DC power supply so as to satisfy the α-sun equation, Even if any of the n superconducting coils is quenched, the next superconducting coil can be controlled at a constant current, thereby preventing the spread and propagation of the quench, thereby providing a superconducting coil power supply device with great energy-saving effects.

〔Effect of the invention〕

As is clear from Equation I above, if the minimum resistance value is selected within the range that satisfies Equation (14a), the rated inverter voltage of the DC current determined from Equation (14b) will be lowered, resulting in a rational and inexpensive power supply device for superconducting coils. can be provided.

[Brief explanation of drawings]

1(a) and 2(a) are circuit diagrams showing the background and principle of the present invention, and FIG. 1(b) and FIG. 2(b) are circuit diagrams showing the background and principle of the present invention.
The current waveform is shown when a quench occurs at =10 and a protective operation is performed. [...Superconducting coil 2...Protective resistor 3...Switch 4...Switch 5...DC power supply agent Patent attorney Noriyuki Chika (and 1 other person) t: Figure 1 (a) -n Wl

Claims (1)

[Claims] 1. A superconducting coil power supply device comprising a plurality of electromagnetically coupled superconducting coils and a protective resistor for absorbing accumulated energy in each superconducting coil, wherein the plurality of superconducting coils are provided with a protective resistor for absorbing accumulated energy. The self-inductance of the coil is, L
,...,Ln, the mutual inductance of the ith superconducting coil and the ith superconducting coil is Mki, and the excitation current value is ``I(1'
t01..., Ino each protection resistance value, -1...,
an, the rated reverse conversion voltage of the DC power supply is [L)rNv+...
・[En) Inv Also, the resistance value per unit length of the wire of the superconducting coil is r1, the weight is m, the specific heat is C1, the normal temperature of the superconducting wire is To, the allowable upper limit temperature is T2, and the dielectric strength of the superconducting coil is Eko. A power supply device for a superconducting coil, characterized in that the value of kotara satisfies the following relational expression when . k=1.2. ...n 2. In a superconducting system that satisfies the above relational expression, when one superconducting coil undergoes a normal conduction transition, the current in the superconducting coil is attenuated by a protective resistor, and the other healthy group superconducting 2. The power supply device for a superconducting coil according to claim 1, wherein the current value of the coil is controlled to be constant.