JP3863316B2 - Semiconductor switching device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor switching device including a GCT thyristor (a gate commutated thyristor having a ring plate-like gate terminal), and more particularly to an improvement for suppressing oscillation associated with turn-off.
[0002]
[Prior art]
Among GTO thyristors (gate commutation thyristors), a type called a GCT thyristor has been known. The GCT thyristor is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-201039, and has an anode electrode and a cathode electrode facing opposite to each other and a ring plate-like gate terminal protruding along the outer periphery. It is characterized by.
[0003]
Since the gate terminal is ring-shaped, the inductance between the gate driver and GCT thyristor is greatly reduced compared to previous GTO thyristors (previously called “old type GTO thyristors”) There is. For this reason, the GCT thyristor has an advantage that it does not require connection of a snubber circuit, unlike an old type GTO thyristor. Since no snubber circuit is required, it is possible to suppress power loss and improve power efficiency.
[0004]
FIG. 6 is a side view showing a main part of a conventional semiconductor switching device including a GCT thyristor. FIG. 7 is a circuit diagram showing an equivalent circuit of the semiconductor switching device 150 whose main part is shown in FIG. As shown in FIG. 6, the device 150 is configured as a stack type semiconductor switching device in which circuit elements are stacked on each other and a terminal plate is inserted between the circuit elements as necessary. .
[0005]
As shown in FIGS. 6 and 7, a flyhole diode 52 is connected in antiparallel to the GCT thyristor 51. The anode electrode A and the cathode electrode K of the GCT thyristor 51 are connected to the main circuit terminal board 55 and the main circuit terminal board 56, respectively. Although not shown in FIG. 6, a gate driver (GDU) 53 is connected to the cathode electrode K and the gate electrode G of the GCT thyristor 51. The gate driver 53 is connected to the gate electrode G through the ring plate-like gate terminal (not shown). The gate driver 53 generates a gate voltage in response to a control signal input from the outside and supplies it to the gate electrode G. Accordingly, the GCT thyristor 51 performs an on / off operation in response to an external signal.
[0006]
Further, a clamp circuit having a clamp diode Dc, a clamp capacitor Cc, and a clamp resistance element Rc is connected to the GCT thyristor 51. One end of the clamp resistance element Rc is connected to the clamp circuit terminal plate 57. Unlike the snubber circuit connected to the old type GTO thyristor, the clamp circuit is always charged with a constant power supply voltage to the clamp capacitor Cc. In the clamp capacitor Cc, there is no charge / discharge accompanying the ON / OFF operation of the GCT thyristor 51. For this reason, unlike the snubber circuit, the clamp circuit has an advantage of low power loss.
[0007]
The snubber circuit also suppresses the temporal change rate (dV / dt) of the voltage between the main electrodes (voltage between the anode electrode A and the cathode electrode K) when the GTO thyristor is turned off. Only the phenomenon in which the voltage between the main electrodes of the GCT thyristor 51 jumps over the power supply voltage is suppressed. The GCT thyristor has an advantage that a clamp circuit with less power loss than a snubber circuit is sufficient as a protection circuit to be connected.
[0008]
As shown in FIG. 6, the GCT thyristor 51 and the fly hall diode 52 are stacked adjacent to each other so that the anode electrode A of the GCT thyristor 51 and the cathode electrode K of the fly hall diode 52 face each other. A main circuit terminal plate 55 is sandwiched between the anode electrode A of the GCT thyristor 51 and the cathode electrode K of the flyhole diode 52.
[0009]
The main circuit terminal board 56 is in contact with and connected to the cathode electrode K of the GCT thyristor 51. Further, the cathode electrode K of the GCT thyristor 51 and the anode electrode A of the flyhole diode 52 are connected to each other through the intermediate connection terminal plate 54. The intermediate connection terminal plate 54 has one end in contact with the main circuit terminal plate 56 and the other end in contact with the anode electrode A of the fly-hole diode 52.
[0010]
The pressing force is applied through the stack electrode 59 and the stack electrode 60 between the electrodes and terminal plates that are in contact with each other and between the terminal plates that are in contact with each other without being fixed by brazing or the like. It is in pressure contact. Since the intermediate connection terminal plate 54 connects the electrodes separated from each other in a bridging manner, the intermediate connection terminal plate 54 has an inductance L of a certain size as shown in FIG.
[0011]
[Problems to be solved by the invention]
Since the semiconductor switching device 150 provided with the conventional GCT thyristor is configured as described above, it has the following problems.
In order to turn off the GCT thyristor 51, a reverse bias voltage of several tens of volts is first applied between the gate electrode G and the cathode electrode K. At this time, a closed circuit 65 is formed, which is a path that sequentially follows the gate driver 53, the intermediate connection terminal plate 54, the fly Hall diode 52, and the GCT thyristor 51. Therefore, a minute current for charging the junction capacitance inside the GCT thyristor 51 flows along the closed circuit 65. This minute current becomes a forward current with respect to the fly-hole diode 52.
[0012]
Thereafter, the operation of the GCT thyristor 51 shifts from the on state to the turn-off operation. Along with this, a constant power supply voltage is applied between the main electrodes of the GCT thyristor 51. This power supply voltage is a reverse voltage with respect to the fly-hole diode 52. Therefore, as the GCT thyristor 51 is turned off, the operation of the fly-hole diode 52 moves from a state in which a minute forward current flows to reverse recovery.
[0013]
In the GCT thyristor 51, as described above, since the protection is achieved without the snubber circuit, the GCT thyristor 51 is used without connecting the snubber circuit by taking advantage of the advantage, thereby reducing the power loss. ing. However, since there is no snubber circuit, the voltage increase rate dV / dt accompanying the turn-off of the GCT thyristor 51 is a high value. Therefore, the fly-hole diode 52 is forced to go to reverse recovery by applying a reverse voltage at a high voltage increase rate dV / dt from a state where a low forward current flows.
[0014]
When the forward current of the fly-hole diode 52 is small, the number of carriers stored in the fly-hole diode 52 is also small. When a reverse voltage is applied from this state, the fly-hole diode 52 easily oscillates. Also, the more the rise of the reverse voltage is steeper, that is, the higher the voltage increase rate dV / dt, the easier the oscillation occurs. Therefore, when a reverse voltage is applied from a small forward current at a high voltage increase rate dV / dt, oscillation easily occurs in the fly-hole diode 52, in particular.
[0015]
FIG. 8 is a waveform diagram showing the result of measuring the signal waveform of each part of the device 150 accompanying the turn-off operation. As shown in FIG. 8, when the gate voltage V _{G of} about 20 V supplied by the gate driver 53 decreases, the turn-off operation is started. When the turn-off operation is started, the main current I _T decreases from the steady 2000 A value toward zero, and at the same time, the main interelectrode voltage V _DM increases from about zero to a power supply voltage of about 3000 V. During this process, the fly-hole diode 52 oscillates, and oscillation appears in the return current I _FWD . The oscillation of the reflux current I _FWD also affects the GCT thyristor 51, and an oscillation phenomenon appears in any of the gate voltage V _G , the main current I _T , and the main electrode voltage V _DM .
[0016]
Such vibrations generated in the signals of each part propagate as noise to an external circuit installed around the device 150. For this reason, the apparatus 150 has a problem that it requires a measure for preventing noise. Further, the GCT thyristor 51 itself may be prevented from performing a smooth turn-off operation due to the vibration in the signal of each part of the GCT thyristor 51.
[0017]
In the old type GTO thyristor, in addition to using a snubber circuit, the inductance between the GTO thyristor and the gate driver is about 100 times higher than the inductance between the GCT thyristor and the gate driver. There is no oscillation problem. That is, oscillation is a problem specific to GCT thyristors.
[0018]
The present invention has been made to solve the above-described problems in conventional devices, and provides a semiconductor switching device that suppresses oscillation associated with turn-off, suppresses noise generation, and realizes a smooth turn-off operation. The purpose is to do.
[0019]
As a technique related to the present invention, Japanese Patent Laid-Open No. 10-75564 which discloses a semiconductor switching device including an old type GTO thyristor is known.
[0020]
[Means for Solving the Problems]
A device according to a first aspect of the present invention is a semiconductor switching device, and includes a gate commutation thyristor having an anode electrode and a cathode electrode facing opposite to each other and having a ring-plate-like gate terminal extending along the outer periphery. A flywheel diode having an anode electrode and a cathode electrode facing each other, the cathode electrode facing the anode electrode of the gate commutated thyristor, and the anode of the gate commutated thyristor A first main circuit terminal plate sandwiched between an electrode and the cathode electrode of the flywheel diode and connected to these electrodes; and facing the anode electrode of the flywheel diode and connected to the anode electrode A second main circuit terminal plate and the cathode electrode of the gate commutated thyristor Comprising an intermediate connection terminal board for connecting the anode electrode of the flywheel diode, the.
[0021]
According to a second aspect of the present invention, in the semiconductor switching device of the first aspect, the first main circuit terminal plate is in pressure contact with the anode electrode of the gate commutated thyristor and the cathode electrode of the flywheel diode. The second main circuit terminal plate is in pressure contact with the anode electrode of the flywheel diode, and the intermediate connection terminal plate is connected to the second main circuit terminal plate and the cathode electrode of the gate commutated thyristor. Is in pressure contact.
[0022]
According to a third aspect of the present invention, in the semiconductor switching device of the first aspect, the second main electrode terminal and the intermediate connection terminal plate are each part of a common terminal plate integrally connected.
[0023]
According to a fourth aspect of the present invention, in the semiconductor switching device of the third aspect, the first main circuit terminal plate is in pressure contact with the anode electrode of the gate commutated thyristor and the cathode electrode of the flywheel diode. The common terminal plate is in pressure contact with the anode electrode of the flywheel diode and the cathode electrode of the gate commutated thyristor.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
(1. Device configuration)
FIG. 1 is a side view showing a main part of a semiconductor switching device according to an embodiment including a GCT thyristor. FIG. 2 is a circuit diagram showing an equivalent circuit of the semiconductor switching device 101 whose main part is shown in FIG. As shown in FIG. 1, the device 101 is configured as a stack type semiconductor switching device in which circuit elements are stacked on each other and a terminal plate is interposed between the circuit elements as necessary. .
[0025]
As shown in FIGS. 1 and 2, a flywheel diode 2 is connected to the GCT thyristor 1 in antiparallel. That is, the anode electrode A of the GCT thyristor 1 is connected to the cathode electrode K of the fly-hole diode 2, and the cathode electrode K of the GCT thyristor 1 is connected to the anode electrode A of the fly-hole diode 2. The anode electrode A and the cathode electrode K of the GCT thyristor 1 are connected to the main circuit terminal board 5 and the main circuit terminal board 6, respectively.
[0026]
Although not shown in FIG. 1, a gate driver (GDU) 3 is connected to the cathode electrode K and the gate electrode G of the GCT thyristor 1. The gate driver 3 is connected to the gate electrode G through a ring plate-like gate terminal (not shown) provided in the GCT thyristor 1. The gate driver 3 generates a gate voltage in response to a control signal input from the outside and supplies it to the gate electrode G. Thereby, the GCT thyristor 1 performs an on / off operation in response to an external signal.
[0027]
Further, the GCT thyristor 1 is preferably connected to a clamp circuit having a clamp diode Dc, a clamp capacitor Cc, and a clamp resistance element Rc. One end of the clamp resistance element Rc is connected to the clamp circuit terminal plate 7.
[0028]
As shown in FIG. 1, the GCT thyristor 1 and the fly Hall diode 2 are stacked adjacent to each other so that the anode electrode A of the GCT thyristor 1 and the cathode electrode K of the fly Hall diode 2 face each other. A main circuit terminal plate 5 is sandwiched between the anode electrode A of the GCT thyristor 1 and the cathode electrode K of the fly Hall diode 2.
[0029]
The main circuit terminal board 6 is in contact with and connected to the anode electrode A of the fly Hall diode 2. Further, the cathode electrode K of the GCT thyristor 1 and the anode electrode A of the fly Hall diode 2 are connected to each other through the intermediate connection terminal plate 4. The intermediate connection terminal plate 4 has one end in contact with the main circuit terminal plate 6 and the other end in contact with the cathode electrode K of the GCT thyristor 1.
[0030]
A pressing force is applied through the stack electrode 9 and the stack electrode 60 between the electrodes and terminal plates that are in contact with each other and between the terminal plates that are in contact with each other without being fixed by brazing or the like. It is in pressure contact. The intermediate connection terminal plate 4 has a certain inductance L as shown in FIG. 2 because it connects the electrodes separated from each other in a bridging manner.
[0031]
FIG. 3 is a circuit diagram illustrating how the apparatus 101 is used. In the example of FIG. 3, a pair of devices 101 a and 101 b connected in series is interposed between a positive power supply line 22 and a negative power supply line 23 connected to a capacitor 20 that holds a constant power supply voltage V _D. Yes. Each of the devices 101a and 101b is configured the same as the device 101. The anode electrode A of the GCT thyristor 1 belonging to the apparatus 101 a is connected to the positive power supply line 22, and the cathode electrode K of the GCT thyristor 1 belonging to the apparatus 101 b is connected to the negative power supply line 23.
[0032]
One end of a load 21 is connected to a connection portion between the cathode electrode K of the GCT thyristor 1 belonging to the apparatus 101a and the anode electrode A of the GCT thyristor 1 belonging to the apparatus 101b. The other end of the load 21 is connected to the negative power supply line 23, for example. For example, when the GCT thyristor 1 belonging to the apparatus 101a and the GCT thyristor 1 belonging to the apparatus 101b are alternately turned on, a load current is supplied to the load 21 in a pulsed manner.
[0033]
In addition, one end of the clamp resistance element Rc belonging to the device 101 a is connected to the negative power supply line 23, and one end of the clamp resistance element Rc belonging to the device 101 b is connected to the positive power supply line 22. As a result, both clamp capacitors Cc are constantly charged with the power supply voltage V _D.
[0034]
(2. Device operation)
In the apparatus 101, as described above, the main circuit terminal plate 6 is directly connected to the anode electrode A of the fly-hole diode 2, whereas the cathode connection K is connected to the cathode electrode K of the GCT thyristor 1. It is connected via the terminal board 4. Therefore, as shown in FIG. 2, the inductance between the anode electrode A of the fly-hole diode 2 and the main circuit terminal plate 6 is sufficiently low, whereas the cathode electrode K and the main circuit terminal plate of the GCT thyristor 1 are sufficiently low. 6, the inductance L of the intermediate connection terminal plate 4 is interposed. This is because, in the conventional device 150 (FIG. 7), the inductance between the cathode electrode K of the GCT thyristor 51 and the main circuit terminal plate 56 is sufficiently low, whereas the anode electrode A of the flyhole diode 52 and the main circuit. In contrast to the fact that the inductance L of the intermediate connection terminal plate 54 is interposed between the terminal plate 56 and the terminal plate 56.
[0035]
When a reverse bias voltage of several tens of volts is applied between the gate electrode G and the cathode electrode K of the GCT thyristor 1, the GCT thyristor 1 starts to turn off. In the transition period from the ON state to the OFF state, that is, in the process of the turn-off operation, the inductance L included in the closed circuit 15 that sequentially follows the gate driver 3, the intermediate connection terminal plate 4, the flywheel diode 2, and the GCT thyristor 1 includes The main current I _T flows while being attenuated. In other words, a much larger main current I _T flows through the inductance L than the minute current supplied by the gate driver 3 and causing vibration. Therefore, since the influence of the minute current is relatively weakened, the oscillation accompanying the turn-off as seen in the conventional device 150 is suppressed.
[0036]
FIG. 4 is a waveform diagram showing the results of a test conducted to verify this effect, and shows signal waveforms at various parts associated with the turn-off operation of the apparatus 101. As shown in FIG. 4, the turn-off operation is started when the gate voltage V _{G of} about 20 V supplied by the gate driver 3 decreases. When the turn-off operation is started, the main current I _T decreases from the steady 2000 A value toward zero, and at the same time, the main interelectrode voltage V _DM increases from about zero to a power supply voltage of about 3000 V.
[0037]
As shown in FIG. 4, no oscillation phenomenon is observed in the turn-off operation, and both the main current I _T and the main interelectrode voltage V _DM smoothly change from the on-state value to the off-state value. There is a transition. As described above, in the device 101, the oscillation phenomenon that appears in the conventional device 150 is suppressed by simply changing the arrangement of the elements in the stack structure.
[0038]
(3. Modifications)
FIG. 5 is a side view showing a main part of a semiconductor switching device according to a modification. This device 102 is characteristically different from the device 101 (FIG. 1) in that the main circuit terminal board 6 and the intermediate connection terminal board 4 are integrated as a common terminal board 16. The main circuit terminal board 6 and the intermediate connection terminal board 4 are different parts of the common terminal board 16 that are integrally connected to each other, and both terminal boards are eliminated into a single component. For this reason, the assembling process of the apparatus is facilitated and the cost required for assembling can be reduced. The effect that the oscillation is suppressed is obtained in the same manner as the device 101.
[0039]
【The invention's effect】
In the apparatus of the first invention, the second main circuit terminal plate and the anode electrode of the flywheel diode face each other and are connected with low inductance, whereas this anode electrode and the cathode electrode of the gate commutated thyristor are connected. Are separated from each other and are connected to each other via the inductance of the intermediate connection terminal plate. For this reason, in the process of the turn-off operation, the main current flows through the inductance of the intermediate connection terminal plate while being attenuated, so that the influence of the minute forward current of the fly-hole diode that causes the oscillation is canceled out and the oscillation is suppressed. . As described above, in the device of the first invention, an oscillation phenomenon associated with the turn-off operation, which is a phenomenon peculiar to the semiconductor switching device including the GCT thyristor, is suppressed, which is not expected from Japanese Patent Laid-Open No. 10-75564. Is obtained.
[0040]
In the apparatus according to the second aspect of the present invention, the connection portions of the terminal plates, the electrodes, and the connection portions of the terminal plates are in pressure contact, so that the assembly, disassembly, and change of the device are easy.
[0041]
In the device of the third invention, since the second main circuit terminal plate and the intermediate connection terminal plate are integrated into a common terminal plate, the assembly process of the device is facilitated and the cost required for the assembly is reduced. Is done.
[0042]
In the device according to the fourth aspect of the invention, the connection portions of the terminal plates and the electrodes and the connection portions of the terminal plates are in pressure contact, so that the assembly, disassembly, and change of the device are easy.
[Brief description of the drawings]
FIG. 1 is a side view of a main part of an apparatus according to an embodiment.
FIG. 2 is a circuit diagram of an apparatus according to an embodiment.
FIG. 3 is a circuit diagram illustrating a usage pattern of the device according to the embodiment;
FIG. 4 is a waveform diagram showing a turn-off characteristic of the apparatus according to the embodiment.
FIG. 5 is a side view of a main part of a modified apparatus.
FIG. 6 is a side view of a main part of a conventional apparatus.
FIG. 7 is a circuit diagram of a conventional device.
FIG. 8 is a waveform diagram showing a turn-off characteristic of a conventional device.
[Explanation of symbols]
1 GCT thyristor (gate commutation thyristor), 2 fly Hall diode, 4 intermediate connection terminal board, 5 main circuit terminal board (first main circuit terminal board), 6 main circuit terminal board (second main circuit terminal board), 16 Common terminal board, A anode electrode, K cathode electrode.

Claims (4)

A gate commutated thyristor having an anode electrode and a cathode electrode facing each other and having a ring plate-like gate terminal extending along the outer periphery;
A flywheel diode having an anode electrode and a cathode electrode facing to each other, the cathode electrode facing the anode electrode of the gate commutated thyristor;
A first main circuit terminal plate sandwiched between and connected to the anode electrode of the gate commutated thyristor and the cathode electrode of the flywheel diode;
A second main circuit terminal plate facing the anode electrode of the flywheel diode and connected to the anode electrode;
An intermediate connection terminal plate for connecting the cathode electrode of the gate commutated thyristor and the anode electrode of the flywheel diode;
A semiconductor switching device comprising: The first main circuit terminal plate is in pressure contact with the anode electrode of the gate commutated thyristor and the cathode electrode of the flywheel diode;
The second main circuit terminal plate is in pressure contact with the anode electrode of the flywheel diode;
2. The semiconductor switching device according to claim 1, wherein the intermediate connection terminal plate is in pressure contact with the second main circuit terminal plate and the cathode electrode of the gate commutated thyristor. 2. The semiconductor switching device according to claim 1, wherein the second main electrode terminal and the intermediate connection terminal plate are each part of a common terminal plate connected together. The first main circuit terminal plate is in pressure contact with the anode electrode of the gate commutated thyristor and the cathode electrode of the flywheel diode;
The semiconductor switching device according to claim 3, wherein the common terminal plate is in pressure contact with the anode electrode of the flywheel diode and the cathode electrode of the gate commutated thyristor.

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