JPH069174B2 - Superconducting coil device - Google Patents

Description

The present invention relates to a superconducting coil device equipped with a novel protective device.

[Conventional technology]

FIG. 5 is a circuit diagram showing an example of a conventional superconducting coil device shown in "Applied Superconductivity" (published by Nikkan Kogyo Shimbun) edited by Hiroyasu Hagiwara. FIG. 6 is an explanatory diagram showing temporal changes in voltage, current, etc., when a coil is quenched.
The (a) diagram shows the coil voltage, the (b) diagram shows the same current, and the (c) diagram shows the temporal change of the output voltage (bridge voltage) of the bridge circuit (described later) for detecting the quench. In FIG. 5, (1) is a DC power supply, (2) is a circuit breaker provided on the load side of the DC power supply (1), (2a) is a trip coil of the circuit breaker (2),
(3) is a superconductor coil excited by the DC power supply (1) through the circuit breaker (2), and the first and second coils (3a) and (3b) having substantially the same inductance are connected in series. One output terminal (4a) is provided at the connection point of the first and second coils (3a) and (3b). (5a), (5b)
Is an impedance element, in the present example, resistors having the same value, and the one provided with the other output terminal (4b) at the intermediate point where each is connected in series as shown in the figure is parallel to the coil (3). Connected to each other, the coils (3a) and (3b) and the resistors (5a) and (5b) form a bridge circuit (6) having output terminals (4a) and (4b). This bridge circuit (6) and coil (3a)
Since (3b) has almost the same inductance, the effects of the inductance components of the coils (3a) and (3b) are canceled out, and the voltage between the output terminals (4a) and (4b) (hereinafter referred to as bridge voltage). ), The voltage at the quench portion appears as a bridge voltage when a quench occurs in the coil (3a) or (3b). Reference numeral (7) is a voltage detection device, which is composed of an amplifier (7a) and a voltage relay (7b) and emits a signal when the bridge voltage of the bridge circuit (6) exceeds a predetermined value to release the trip coil. The circuit breaker (2) is opened by (2a). Reference numeral (8) is a protective resistor which is connected in parallel to the coil (3) and consumes energy of the coil (3) as Joule heat when a quench occurs in the coil (3).

In the superconducting coil device configured as described above, for example, the operation when a quench occurs in the portion (A) of the coil (3a) will be described with reference to FIG. The breaker (2) is opened and the coil (3) is driven to a constant voltage E by the DC power supply (1).
Excitation is performed at [V] (Fig. 6 (a)). When the inductance of the coil (3) is L [H], the coil current increases at a constant rate according to the equation E = di / dt. For example, when a DC voltage of 16.7 [V] is applied to a coil (3) with an inductance of 1 [H], it is 1000 [A / min] (16.7 [A / s]) at a rate of FIG. 6 (b).
The current increases as shown in. The bridge voltage at this time is shown in Fig. 6 (c), but the impedance elements of the bridge circuit, that is, coils (3a), (3b), resistors (5a), (5b) are perfectly balanced. Since it is difficult to cause this, an imbalance of the bridge circuit occurs, and during excitation of the coil (3), a minute residual voltage (ΔV0
[MV]) is present. Here, when the quench starts to occur in the portion (A) of the coil (3a) at time T1,
A resistance is generated in this portion and a bridge voltage as shown is generated. At time T2, the bridge voltage exceeds the predetermined value ΔV1 [mV], and the state where it exceeds this ΔV1 [mV] is the predetermined time ΔT [s].
Then, at time T3, the voltage detection device (7) operates to emit a signal to open the circuit breaker (2) and stop the excitation of the coil (3). When the circuit breaker (2) is opened, the current in the coil (3) sharply decreases as shown in Fig. 6 (b), so the coil (3)
The voltage changes rapidly as shown in FIG. 6 (a) and the polarity is inverted. This voltage is applied to the protective resistor (8) and the energy stored in the coil (3) is consumed as Juille heat, and the voltage of the coil (3) decreases and finally becomes zero.

In the above conventional example, the bridge circuit (6) is used to detect the quench of the coils (3a) and (3b).
This is because the voltage of the minute quench part generated in (3a) and (3b) is detected with high sensitivity to release the energy of the coil (3) to the outside at an early stage. Since the voltage is small, it is particularly necessary. Although not shown, there is some impedance on the power supply side, and the voltage of the coil changes when a quench occurs, so this change is detected and protected without using the bridge circuit (6) as described above. It is also possible.
Since the excitation voltage of the coil is always superimposed, the detection sensitivity is low, but it is used when a large voltage is generated immediately after quenching, as in a tightly wound coil.

[Problems to be Solved by the Invention]

Since the conventional superconducting coil device is configured as described above, the coil is excited by a pulse excitation method using a DC chopper circuit using a switching element such as a thyristor in place of the DC power source (1) in FIG. In this case, since the residual voltage due to the imbalance exists in the bridge circuit (6) as described above, even when the coil is normal, this residual voltage appears as a large bridge voltage periodically, and the coil quench. It is difficult to detect the occurrence with high sensitivity. This will be specifically described with reference to FIG. 7, which is an explanatory diagram showing changes in the coil voltage, the current, and the bridge voltage in this case.
A pulsed voltage E1 [V] is periodically applied to the coil (3) as shown in Fig. (A), and a current of the coil (3) is applied with voltage E1 as shown in Fig. (B). It increases every time. On the other hand, as shown in FIG. 7 (c), the residual voltage ΔV3 [m] when the pulse voltage E1 [V] is applied as the bridge voltage
V] is generated periodically. If the on-time ratio of the DC chopper circuit in this case is 10%, the pulse voltage corresponding to continuous excitation in the conventional example of FIG. 6 is 10 times, and the residual voltage ΔV3 [mV] is the conventional residual voltage. It is 10 times that of ΔV0 [mV]. Therefore, this residual voltage ΔV3
The operation setting value of the voltage detection device (7) must be a high value biased by this amount so as not to operate at [mV]. In this case, the part of the coil (3a) shown in FIG.
When a quench occurs in (A), a bridge voltage as shown in FIG. 7 (d) is generated (in FIG. 7, the time axis is expanded from FIG. 6). Since the set value is biased by the residual voltage ΔV3 [mV] for the above reason, there is a problem that the quench detection sensitivity becomes low even though the bridge circuit (6) is used.

Further, in the case of the method of detecting the change of the voltage of the coil without using the bridge circuit to detect the quench of the coil, the above-mentioned pulse voltage T1 [V] is directly superimposed, not as the residual voltage of the bridge circuit. Further, this method cannot be adopted because the detection sensitivity is lowered and effective protection cannot be performed. The present invention has been made to solve the above problems, and is a superconducting coil equipped with a protection device that is sensitive to the quenching voltage of the coil and can surely detect and protect the quench of the coil without being influenced by the magnitude of the exciting voltage of the coil. The purpose is to obtain the device. Another object of the present invention is to obtain a superconducting coil device having a protective device with high sensitivity, which prevents the unbalance of the bridge circuit from deteriorating the detection sensitivity even if the bridge circuit is used for detecting the voltage of the quench portion.

[Means for Solving the Problems]

A superconducting coil device according to the present invention excites a coil of a superconductor by a direct current chopper circuit, and a voltage detecting means for detecting the voltage of the coil when the direct current chopper circuit is opened in synchronization with the opening and closing of the direct current chopper circuit. The protection means is provided which operates based on the detection voltage of the voltage detection means to stop the excitation of the coil of the superconductor.

Further, using a bridge circuit including the coil as an impedance element to output the quench of the coil as a voltage, when the DC chopper circuit is opened in synchronization with the opening and closing of the DC chopper circuit, the bridge circuit A voltage detecting means for detecting a voltage and a protecting means for operating on the basis of the detected voltage of the voltage detecting means to stop the excitation of the coil of the superconductor are provided.

[Work]

Since the voltage detecting means in the present invention detects the voltage of the coil when the DC chopper circuit is open, the influence of the value of the voltage during excitation of the coil does not appear in the detected value, and the magnitude of the DC voltage varies depending on the magnitude of the DC voltage. Therefore, quench can be detected with high sensitivity. Further, since the unbalance of the bridge circuit used for detecting the voltage of the quench portion does not appear in the detection value of the voltage detecting means, the quench can be detected with high sensitivity by using the bridge circuit.

Example of Invention

FIG. 1 is a block diagram showing an embodiment of the present invention,
In the figure, (2) to (8) are the same as those of the conventional apparatus shown in FIG. (11) is a DC power supply that supplies a constant voltage, (12) is a DC chopper circuit that is connected to this DC power supply (11) to open and close the circuit at a predetermined cycle, and (13) is a DC chopper circuit.
A sampling circuit (13a) that extracts the bridge voltage only when the gate is opened in this example by the voltage detection means that detects the bridge voltage of the bridge circuit (6) when the DC chopper circuit is opened by receiving the synchronization signal from (12). And an amplifier (13b). (14) is a protection means that operates based on the detection voltage of the voltage detection means (13) to open the circuit breaker (2) and stop the excitation of the coil (3) .In this example, the voltage detection means (13) The counter (14a) that counts the number of times the detection voltage, that is, the sampling voltage, exceeds the specified value, and operates when the count value of this counter (14a) exceeds the specified value and issues an open signal to the circuit breaker (2). It is composed of a signal circuit (14b).

Next, the operation will be described. FIG. 2 is an explanatory diagram showing changes in voltage, current, etc., when a quench occurs in the portion (A) of the coil (3a). (a) Coil as shown in the figure
(3) is periodically excited by the pulsed voltage E1 by opening and closing the DC chopper circuit. The current in the coil (3) increases as shown in Fig. (B) every time the pulsed voltage E1 is applied. The voltage detection means (13) opens the gate of the sampling circuit (13a) to extract the bridge voltage when the pulsed voltage E1 is not applied in synchronization with the DC chopper circuit (12), and uses the amplifier (13b) to extract the bridge voltage. It is amplified and output as a sampling voltage to the counter (14a). Therefore, at time T1, when quenching occurs in the coil (3a) portion (A) and the voltage at the quenching portion increases with time, the sampling voltage changes as shown in (c) and exceeds the set voltage ΔV1. Each time, the counter (14a) counts as shown in FIG. When the count value of this counter (14a) exceeds a predetermined value, the trip signal circuit (14b) operates and issues an open signal to the circuit breaker (2) to open the circuit breaker (2) to open the coil ( Stop the excitation in 3). At this time, the energy stored in the coil (3) is consumed by the protective resistance (8) as in the conventional example shown in FIG. In the above, the trip signal circuit (14a) operates after the counter (14a) has counted a predetermined value, because when the counter (14a) miscounts due to noise, the circuit breaker (2 ) Is not released.

FIG. 3 is a block diagram showing another embodiment of the present invention, in which the voltage of the coil (3) is directly detected without using a bridge circuit to detect the voltage of the quench section. In the figure, (23) is a voltage detecting means for detecting the voltage of the coil (3) when the DC chopper circuit (12) is opened by receiving a synchronizing signal from the DC chopper (12), and when the gate is opened. coil
The sampling circuit (23a) for extracting the voltage of (3) and the amplifier (2
3a) and. (24) operates based on the voltage detected by the voltage detection means (23) to open the circuit breaker (2) to open the coil (3)
Is a protection means to stop the excitation of the
And a voltage relay (24b).

Next, the operation of this embodiment will be described. FIG. 4 is an explanatory diagram showing changes in voltage, current, etc. when the coil is quenched, and the voltage and current applied to the coil (3) are the same as those in FIGS. 2 (a) and (b). is there. When the DC chopper circuit (12) is opened by the sampling circuit (23a), the gate is opened and the voltage of the coil (3) is taken out and amplified by the amplifier (23b) and output as the sampling voltage. If this sampling voltage increases with time due to the occurrence of a quench in part (A) of the coil (3a) at time T1,
(c) Changes as shown in the figure. This sampling voltage is integrated by the integration circuit (24a) and output, and the predetermined value ΔV4
When it reaches [V], the voltage relay (24b) operates and the circuit breaker
Open (2).

In the embodiment shown in FIG. 1, the coil (3) is composed of two coils (3a) and (3b) to form a set of bridge circuits.
Although (6), the voltage detecting means (13) and the protecting means (14) are shown, the coil (3) is divided into a larger number of coils, and a plurality of sets of bridge circuits, voltage detecting means and protecting means are provided. Even if it is provided and protected, the same effect can be obtained.

Also in the embodiment shown in FIG. 3, for example, the voltage detecting means (23) and the protecting means (24) may be provided for each of the coils (3a), (3b) constituting the coil (3). Protective measures (14), (24)
It is also possible to stop the excitation on the DC power supply (11) side without opening the circuit breaker (2) by the operation of. In this case, the breaker (2) can be omitted.

Further, although the synchronous signal for the voltage detecting means (13) and (23) is received from the DC chopper circuit (12) to perform sampling, the coil (3) or the coil constituting the coil (3) is shown.
Sampling may be performed by detecting the voltages of (3a) and (3b) and determining the presence or absence of the excitation voltage, and the width of the sampling time may be set arbitrarily. The method of adjusting the opening / closing time ratio of the DC chopper circuit may be either pulse width modulation or pulse frequency modulation, and the present invention can be applied to opening / closing that does not have regularity in time. The structure of the means may be arbitrarily selected within a range that does not impair the object of the present invention.

〔The invention's effect〕

As described above, according to the present invention, the coil of the superconductor is excited by the DC chopper circuit, and the voltage of the coil is detected when the DC chopper circuit is opened in synchronization with the opening and closing of the DC chopper circuit. Therefore, quench can be detected with high sensitivity without being affected by the magnitude of the excitation voltage, and reliable protection can be achieved at an early stage.

Therefore, the quench can be detected with sufficiently high sensitivity without using a bridge circuit for detecting the voltage of the quench portion of the coil, and in this case, it is not necessary to provide an output terminal for configuring the bridge circuit in the middle portion of the coil. In addition, there is no possibility that an abnormal voltage will be generated at the output terminal when the quench occurs and the coil will be burned.

Further, when the bridge circuit is used to detect the voltage of the quench section, it is not necessary to increase the operating value of the protection means in order to cope with the imbalance of the values of the impedance elements that form the bridge circuit, and the sensitivity is good. Quench can be detected.

[Brief description of drawings]

1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory view showing changes in voltage, current, etc. when a coil is quenched, and FIG. 3 is another embodiment of the present invention. The block diagram shown in Fig. 4 is the voltage when a quench occurs,
FIG. 5 is an explanatory diagram showing changes in current, etc., FIG. 5 is a circuit diagram showing an example of a conventional superconducting coil device, FIG. 6 is an explanatory diagram showing changes in voltage, current, etc. when a quench occurs, and FIG. It is explanatory drawing which shows the change of a voltage, a current, etc., when a coil of a superconductor is excited by a DC chopper circuit. In the figure, (3) is a superconductor coil, (3a) and (3b) are first and second coils, (6) is a bridge circuit, (12) is a direct current chopper circuit, and (13) and (23). Is voltage detection means, (14), (24)
Is a safeguard. In the drawings, the same reference numerals indicate the same or corresponding parts.

Front page continued (72) Inventor Katsuyoshi Toyota 1-2-2 Wadazaki-cho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Electric Corporation Kobe Works (72) Inventor Yasuhiko Hosokawa 1 Wadazaki-cho, Hyogo-ku, Kobe-shi, Hyogo 1-2, Mitsubishi Electric Co., Ltd. Control Works (72) Inventor Naohiro Toki 1-2-2, Wadazakicho, Hyogo-ku, Kobe, Hyogo Prefecture Mitsubishi Electric Co., Ltd.

Claims (2)

[Claims] 1. A DC chopper circuit, a coil of a superconductor connected to the DC chopper circuit to be excited, and a voltage of the coil is detected when the DC chopper circuit is opened in synchronization with opening and closing of the DC chopper circuit. A superconducting coil device comprising voltage detection means and protection means that operates based on the voltage detected by the voltage detection means to stop the excitation. 2. A direct current chopper circuit, a coil of a superconductor connected to the direct current chopper circuit to be excited, a bridge circuit including the coil as an impedance element and configured to output the quench of the coil as a voltage, the direct current. It is provided with a voltage detecting means for detecting the voltage of the bridge circuit when the DC chopper circuit is opened in synchronization with the opening and closing of the chopper circuit, and a protection means for operating based on the detected voltage of the voltage detecting means to stop the excitation. Superconducting coil device.