JPH01255436A - Semiconductor circuit breaker - Google Patents

Abstract

PURPOSE:To effectively protect a power semiconductor element with a simple structure by connecting a superconducting element having critical value control means in series with a semiconductor element. CONSTITUTION:A high temperature superconducting element 3 is connected in series with a semiconductor element 1, and a control coil for controlling the critical value of the element 3 by applying a magnetic field is provided. The element 3 is cooled by liquid nitrogen to become a superconducting state at a normal time, and conducted without loss. When an overcurrent is generated due to a short-circuit of a load, it is detected by a detector, not shown, and the control 4 is energized. Thus, the magnetic field given by the element 3 exceeds the superconducting critical magnetic field intensity of the element 3 to destroy the superconducting state, thereby generating a current limiting operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This research relates to overcurrent protection of a semiconductor circuit breaker used to turn on and off a power supply circuit.

[Conventional technology]

Figure 4 shows the configuration of a conventional semiconductor circuit breaker.
) are power semiconductor elements such as gate turn-off thyristors or silicon-controlled rectifiers called GTOs, and are connected in parallel in opposite directions. (2) is a high speed current limiting fuse, which is connected in series to the power semiconductor element (1). A and B are terminals connected to the Wt source or load of this power supply circuit, respectively. Although FIG. 4 shows a single-phase example, in the case of three-phase, three of the devices shown in FIG. 4 are used in parallel.The operation will now be described. In a normal state, power is supplied from the power supply side to the load side through the power semiconductor elements (1) connected in parallel in opposite directions in the fourth (2). At this time, for example, if a short circuit accident occurs on the load side, a very large current will flow through the power semiconductor element (1).
Generally, the heat capacity and thermal time constant are small, so there is a problem that the circuit opening/closing function is lost. A high-speed current-limiting fuse (2) is provided for this purpose, and it quickly limits the current before a short-circuit occurs in the circuit and a very large DC current flows through the power semiconductor device (1). - Protect the power semiconductor element (1) by shutting off.

[Problem to be solved by the invention]

Since the conventional semiconductor circuit breaker is configured as described above, when the high-speed current-limiting fuse (2) performs the legal operation of the semiconductor element (1), the high-speed current-limiting fuse (2) must be replaced. However, there was the problem that power outages were inevitable in order to replace the defeat. Also, in the current limiting operation of the high speed current limiting fuse (2), although it is a short time until the fuse melts,
There was a problem that a large direct current flows through the semiconductor element (1). This invention was made to solve the above-mentioned problems, and it can reliably limit the current even if a large current attempts to flow due to an accident such as a short circuit, and also eliminates the need for replacement even after the protective function is activated. [Means for Solving the Problem] A semiconductor circuit breaker according to the present invention has a superconducting element connected in series to a semiconductor element.

[Effect]

The semiconductor circuit breaker related to this invention utilizes the phase change of a superelectric element connected in series with a semiconductor element from a superconducting state to a normal conducting state, and changes the superconducting state of the superelectric element when an overcurrent occurs due to an accident. This destroys the superelectric element to create resistance and perform current-limiting operation, and after the point of failure is removed, the superconducting state of the superelectric element is restored to continue supplying electricity.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, (1) is a semiconductor element similar to that explained in the above conventional example, and (3) is a high-temperature superstructure made of, for example, yttrium-based or bismuth-based oxide ceramic connected in series to the semiconductor element (1). An electric element (4) is a control coil that controls the super-VJt conduction critical value of the super-electric element (3) by applying a K magnetic field to the super-electric element (3) by excitation; ) and (6) are the terminals of the control coil (4), which house the control coil (4) and store liquid nitrogen inside after receiving supply from a liquid nitrogen supply means (not shown). is connected to a control device (not shown).

A and B are terminals connected to a power source and a load, respectively.

No. 11\1 indicates one phase, and in the case of a three-phase circuit, three of the above will be used.

Next, the operation will be explained. In Figure 1, under normal conditions, the superelectric element (3) is cooled by liquid nitrogen to below the critical temperature of superconductivity, so it is in a superconducting state and the power supplied from the power source is lost in the superelectric element (3). The semiconductor element (1) is bent and supplied to the load without causing any damage. If an accident such as a short circuit occurs on the load side and a large current attempts to flow, an abnormality in the main circuit is detected by the main circuit current monitoring means (not shown), and the superelectric element (3) is switched from the superconducting state to normal conduction. Transition to state Iii'lj Cape command output command. Specifically, the terminal (6) is d to excite the control coil (4), which causes the super 1TV dynamic element (
The @ field applied to 3) exceeds the superconducting critical magnetic field strength of the super 4 element (3), and as a result, the superconducting state of the super 4 element (3) is destroyed, resistance is generated, and current limiting action occurs. .

The superconductive criticality of the superelectric element (3) is affected not only by the strength of the magnetic field but also by the current density. If a direct current exceeding the superconducting critical current density flows and the superconducting state is destroyed,
Since the current flowing through the superconducting element (+3) has a substantially constant value, the current limiting function can be obtained even without the control coil (4) as shown in FIG.

However, due to variations in component dimensions that occur during the fabrication of the super 114 element (3), there will be considerable variation in the value of the current limiting starting DC. It is desirable to use 4) to control the current limiting start current more accurately.

In the above embodiment, the control coil (4) is controlled by another control means (not shown), but as shown in FIG. 2, the control coil (4) may be connected in series with the main circuit. Also, the same effect as the above embodiment is achieved.

In addition, although this example shows an example of a superconducting element (3) that produces a superconductive phenomenon by cooling with liquid nitrogen, a superelectric element (3) having a higher critical temperature, such as room temperature,
In that case, it goes without saying that the heat insulating tank (5) becomes unnecessary.

〔Effect of the invention〕

As described above, according to the present invention, since the superconducting element having a critical value control means is connected in series with the semiconductor element, the power semiconductor element can be reliably protected against overcurrent with a simple configuration. This has the effect that it is possible to obtain a power semiconductor circuit breaker that can perform.

Furthermore, as described above, according to Ike's invention, since the superelectric element is connected in series with the semiconductor element, the power semiconductor element can be reliably protected against overcurrent with a simple configuration. This has the effect that it is possible to obtain a power semiconductor circuit breaker that can perform.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a semiconductor circuit breaker 2g according to an embodiment of the invention, FIG. 2 is a circuit diagram showing the configuration of a semiconductor circuit breaker according to another embodiment of the invention, and FIG. FIG. 4 is a circuit diagram showing still another embodiment. FIG. 4 is a circuit diagram showing the configuration of a conventional semiconductor circuit breaker. In the figure, (1) is a semiconductor element, (3) is a superelectric element, and (4) is a control coil. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A semiconductor circuit breaker comprising at least a semiconductor element and a superelectric element having critical value control means connected in series to the semiconductor element. (2) A semiconductor circuit breaker including at least a semiconductor element and a superconducting element connected in series to the semiconductor element.