JPS605064B2 - Thyristor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thyristor control device having a path for separating a control signal superimposed on a main signal from a main signal path and applying the separated control signal to a control electrode of an electrostatic induction thyristor. .

The slave thyristor is controlled by applying a control signal to a control electrode other than the main electrode, or by temporarily applying a voltage higher than the forward blocking voltage to the main electrode.

In the former case, three terminals and a signal other than the main current are required as a control signal, making the control method complicated, which is particularly difficult when controlling a syringe located far away. Moreover, the latter case has a major drawback in that it affects the main current. This invention eliminates the above-mentioned drawbacks by separating the control signal superimposed on the main signal from the main signal of the electrostatic induction thyristor, and applying this separated control signal to the control electrode of the electrostatic induction thyristor. A means for controlling the thyristor is provided, and the thyristor is controlled by this means.

This invention will be explained below. FIG. 1 is a circuit diagram schematically showing an embodiment of the present invention, which is composed of a thyristor and a capacitor 2 inserted between a control electrode 5 and an anode 3.

When a voltage with a superimposed alternating current or pulse control signal having a higher frequency than the direct current or alternating main current is applied between the anode 3 and the cathode 4, the control signal is applied to the control electrode 5 through the capacitor 2, Thyristor control is performed. Here, a coil may be inserted into the path of the main current, and in that case, the main current and the control signal are further separated. To explain the case where the control device of the present invention is used outside of a conventional PNPN four-layered Siris, superimposing a control signal on the main current, even if it is a high frequency alternating current or pulse, A high voltage will be applied to the main electrode, which may cause the thyristor to switch.

When the magnitude of the control signal is such that the thyristor does not switch, the potential of the control electrode as viewed from the cathode is high, but the conventional pnpn structure thyristor does not switch on without carrier injection. That is, this method does not offer much advantage over thyristors having a conventional pnpn structure. For the above reasons, the present invention is particularly advantageous when used in a static induction thyristor (hereinafter referred to as SIT). This will be explained below. First, the structure and operating principle of the electrostatic induction thyristor will be briefly explained.

FIG. 2 is a sectional view showing an example of an electrostatic induction thyristor.

The anode 3 is formed by introducing p-type impurities into an n-type substrate 6, and has a p+-type control electrode 5 distributed in a comb shape or a mesh shape on the opposite main surface, and is further formed by a method such as vapor phase growth on the anode 3. An n layer 61 is present, and the cathode 4 is formed by providing an n+ layer selectively or entirely in contact with the surface thereof. As shown in Figure 3, the operating characteristics of SIT are as follows: anode current 1^ - anode-cathode voltage V^K, which is similar to that of a normal thyristor.
Show characteristics.

However, SIT is normally in a conductive state (■) when a small voltage V between the anode and cathode is applied in the forward direction, and becomes a current blocking state (■) when a negative voltage VG is applied between the cathode and the control electrode. . In order to maintain this current blocking state (2), a negative voltage VG and a control current IG must be allowed to flow. The features of the present invention are best exhibited when the anode current 1^ and the control current lc do not need to flow at the same time. The reason why it is necessary to apply a negative voltage VG and flow the control current IG when keeping the anode current 1^ in a blocked state is because a forward bias is applied between the anode 3 and the cathode 4, so holes are removed from the anode 3. However, since electrons are injected from the cathode 4, the purpose is to prevent this by forming a depletion layer region 51 around it by the electrostatic potential of the control electrode 5, and to control the holes injected from the anode. By absorbing the electrode 5 and preventing a drop in electrostatic potential, the anode and cathode are maintained in a blocking state. When the control current IG that flows through the control electrode 5 ceases to flow, a large amount of electrons and holes are accumulated in the depletion layer region 51, and as a result, it is considered that the current blocking ability is lost. Therefore,
SIT can be turned on by cutting off the control current IG. In addition, in order to shift from the on state to the off state, electrons and holes existing between the control electrodes 5 are drawn out as a control current lc to reduce their density, and the depletion layer region 51
must be revived. Next, the operation of this invention will be described.

In FIG. 1, the main current path is initially in a conductive state. When a negative control signal multiplied by the main current enters the main current for a certain period of time, it becomes a large resistance in the main current path due to the inductance in the main current path and proceeds to the control electrode circuit. In this case, it is more effective if a coil is inserted into the main current path. This negative control signal expands the depletion layer around the control electrode and blocks anode current. When this control signal disappears, the main current path is turned on again. The advantage of this control method is that when a surge current or abnormality occurs due to some cause in the main current path, the sudden change in current always contains a high frequency component, which blocks the SIT. As a result, it serves to protect the SIT from overcurrent.

It also has the advantage that wiring etc. are extremely easy when controlling a thyristor located far away. Figure 4, Figure 5, Figure 6
The figure shows another embodiment of the present invention, and FIG. 4 shows a capacitor 2 inserted in series in the main current path, which is an example adopted when the main current path has a much higher frequency than the control signal path. 5 and 6 show the case where the coil 7 is inserted in series in the control circuit or the main current path, and by utilizing resonance at a specific narrow band frequency, the control signal and the above This is used to distinguish between false signals caused by surges, etc.

Figure 7 shows how the main current changes depending on the flow of signal current to the control electrode, where a is the anode current,
b is the control electrode voltage, and c is the control current.

The main current is blocked when the control electrode is negatively biased,
Since it is in a conductive state when it is zero biased or positively biased, the main current is interrupted as shown in FIG. 7a by the voltage pulse shown in FIG. 7b. At this time, a current also flows through the control electrode, and its change is as shown in FIG. FIG. 8 shows still another embodiment of the present invention, in which a capacitor 2 (or coil) is additionally introduced to the control electrode 5, and a signal with a frequency different from the main current or an instantaneous surge current flows. When the main current flows through the control electrode 5, the main current can be instantaneously cut off, and the thyristor 1 can be protected.

In this embodiment, a nonlinear element 8 as shown in the figure is connected in series with a capacitor 2, so that it operates only with signals of a certain magnitude or more. The embodiment of FIG. 8 has a main control signal input circuit 9 from a control signal source for controlling the main thyristor to the control electrode 5 of the thyristor 1, and a sub-control signal input circuit 5' separated from the main current path. This is an example.

Here, the relationship between the main control signal and the sub-control signal can be considered in two cases: one in which they cooperate to realize desired control characteristics, and the other in which they correspond to different control operation modes. As an example of the latter case, the sub-control signal may correspond to an abnormal voltage occurring in the main current path. That is, when an abnormally high voltage pulse is applied to the main current path during normal control operation by the main control signal, this pulse voltage is separated from the main current path and is applied to the control electrode 5 of the main thyristor 1, causing the main thyristor 1 to temporarily The circuit is protected by being put into a blocked state.
In this case, a zener diode, a transistor,
It is effective to insert a nonlinear element 8 such as a thyristor. Generally, when the operating modes of the main control signal system and the sub control signal system are different, it is effective to insert a circuit for separating or selecting signals in one or both paths.
In the above embodiment, the control signal applied to the control electrode 5 was only a signal component separated from the main circuit path, but the invention is not limited to this.

Furthermore, if the control device of the present invention is integrated with a thyristor, the above-mentioned control can be performed with one element, which has the advantage of being a very small and easy-to-use element.

As explained in detail above, this invention separates the control signal from the main signal path and adds the control electrode of the thyristor for control, so the thyristor can be controlled with two terminals.
The control signal has the advantage of being small and does not affect the main current, and has the advantage of being able to be directly inserted into an existing transmission line, and can be applied regardless of whether the main current is direct current or alternating current. can.

Furthermore, due to its characteristics, it has an unprecedented advantage of protecting the transmission line and its associated functions from surges generated in the transmission line due to an accident, and is of extremely high industrial value.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a sectional view showing an example of an electrostatic transfer type thyristor, and Fig. 3 is a SI
Figures 4, 5, and 6 are circuit diagrams showing other embodiments of the present invention, and Figures 7a, b, and c show the main current due to the flow of signal current to the control electrode. FIG. 8 is a circuit diagram showing still another embodiment of the present invention. In the figure, 1 is the silis valve, 2 is the capacitor, 3 is the anode, and 4
is a cathode, 5 is a control electrode, 6 is an n-type substrate, 7 is a coil, 8
9 is a nonlinear element, and 9 is a main control signal input circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. A static induction thyristor having a control electrode of a second conductivity type embedded in a semiconductor layer of a first conductivity type; A thyristor comprising means for separating a control signal superimposed on a main signal of a path and applying the separated control signal to the control electrode, and controlling the electrostatic induction thyristor by this means. Control device. 2. The thyristor according to claim 1, wherein the control signal is a current having a specific frequency component separated from a current in a main signal path obtained by superimposing an alternating current or direct current with a different frequency on an alternating main current. control device. 3. The thyristor control device according to claim 1, wherein the control signal is selectively extracted from the current in the main signal path by a resonant circuit provided in the circuit of the control electrode of the thyristor. 4. The thyristor control device according to claim 1, wherein the control signal is obtained by extracting only a pulse signal from a superposition of a main current applied to the main signal path and a pulse signal. 5. The thyristor control device according to any one of claims 1 to 4, wherein the control signal is a pulsating current or a direct current that is rectified or smoothed after being separated from the current in the main signal path. 6. The thyristor control device according to claim 1, wherein the control signal is obtained by extracting a sudden change in current in the main signal path. 7. The thyristor control device according to any one of claims 1 to 6, wherein the means for extracting the control signal is integrated with the thyristor.