JP2000059191A - Semiconductor switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized semiconductor switch capable of high repetition operations without the need of supplying power from the outside to a driving circuit. SOLUTION: For this semiconductor switch, a snubber capacitor is constituted of plural capacitors Cs1 and Cs2, a second capacitor Cg is parallelly connected through a diode Dg to the one or plural capacitors and the second capacitor Cg is used as the power source of the driving circuit GU of a semiconductor switching element. When the semiconductor switching element SW is turned OFF, the respective capacitors are charged from a main circuit and the second capacitor Cg is charged as well. Also, when the semiconductor switching element SW is turned ON, though the electric charges of the snubber capacitor are discharged, the second capacitor Cg is not discharged since the diode Dg is present and energy is supplied to the driving circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor switch for supplying energy required for a drive circuit of a semiconductor device from a main circuit.

[0002]

2. Description of the Related Art In a pulse power technique used for a laser or a particle accelerator using a large pulse current, a method of obtaining a large pulse current is to discharge a capacitor charged at a high voltage at a high speed by a high-speed switch. Is generally used, and recently, an attempt has been made to apply a semiconductor switch as a high-speed switch.

Since a switch used for pulse power requires a high voltage and a large current of several tens of kilovolts and several kiloamps, when a semiconductor switch is applied, a plurality of semiconductor elements are connected in series as shown in FIG. The method used is generally.

The semiconductor elements SW1 to SWn connected in series in the semiconductor switch shown in FIG. 10 are driven by control signals transmitted from the control device 1 through the optical fiber cable LG to drive circuits GU1 to GU of the semiconductor elements.
n are individually driven by on / off signals from n. Control power for the drive circuits GU1 to GUn of each semiconductor element is supplied from an external power supply PS via insulating transformers Tr1 to Trn. Here, the insulating transformers Tr1 to Trn are insulating transformers for insulating the external power supply PS which is a low voltage circuit and the drive circuits GU1 to GUn of semiconductor elements which are high voltage circuits.

[0005]

In the above-described semiconductor switch, the energy supplied to the drive circuit of each semiconductor element is supplied via the insulating transformer, so that the drive circuit has a large volume and a large weight. Was.

In order to solve this problem, FIG.
A method of establishing a power supply of a drive circuit by dividing a main circuit voltage as shown in FIG. 1 has been proposed (Patent Publication H05-122923). In the system shown in FIG. 11, a voltage dividing resistor DV is connected in parallel to the semiconductor elements of the main circuit in order to equalize the shared voltage between the elements, and the shared voltage charges the capacitor Cp with the control voltage of the Zener diode ZD. Therefore, an insulating transformer or the like is not required.

However, in this case, the repetition frequency of charging and discharging of the switch is restricted by the charging time constant of the capacitor Cp. Rd = 10 (KΩ) as a typical value, Cp
= 1 (μF), the time constant becomes 0.01 second and 100
Operation at repetition frequencies higher than 1 Hz is not possible. This is not a switch that operates at the kilohertz-class repetition that has been increasing in demand recently. Accordingly, it is an object of the present invention to provide a semiconductor switch that does not require external power supply to a drive circuit, and that can be operated in a small size and with high repetition.

[0008]

In order to achieve the above object, in the semiconductor switch according to the first aspect of the present invention, the snubber capacitor is composed of a plurality of capacitors, and a diode is connected to one or more of the capacitors. A second capacitor is connected in parallel through the second capacitor, and the second capacitor is used as a power supply for a drive circuit of the semiconductor switching element. When the semiconductor switching element is turned off, each capacitor is charged from the main circuit, the second capacitor is also charged, and when the semiconductor switching element is turned on, the charge of the snubber capacitor is discharged. It is not discharged because it is present, and energy can be supplied to the driving circuit.

In a semiconductor switch according to a second aspect of the present invention, the snubber capacitor comprises a plurality of capacitors,
A second capacitor is connected in parallel to the one or more capacitors via a diode, and the second capacitor is used as a power supply for a drive circuit of the semiconductor switching element. When the semiconductor switching element is turned off, each capacitor is charged from the main circuit, the second capacitor is also charged,
When the semiconductor switching element is turned on, the electric charge of the snubber capacitor is discharged, but the second capacitor is not discharged due to the presence of the diode, and can supply energy to the drive circuit.

In the semiconductor switch according to a third aspect of the present invention, the snubber capacitor is constituted by a plurality of capacitors,
A second capacitor is connected in parallel to the one or more capacitors via a diode, and the second capacitor is used as a power supply for a drive circuit of the semiconductor switching element. When the semiconductor switching element is turned off, each capacitor is charged from the main circuit, the second capacitor is also charged,
When the semiconductor switching element is turned on, the electric charge of the snubber capacitor is discharged, but the second capacitor is not discharged due to the presence of the diode, and can supply energy to the drive circuit.

In the semiconductor switch according to a fourth aspect of the present invention, a driving circuit of the semiconductor switching element is constituted by the semiconductor element and the insulating transformer, and a switching signal of the semiconductor switching element from the outside is applied to the primary side of the insulating transformer. The control terminal of the semiconductor element is connected to the secondary side. Since this insulating transformer only needs to transmit a drive signal with low energy, it can be made smaller than a transformer that supplies a conventional drive power supply.

In a semiconductor switch according to a fifth aspect of the present invention, a drive circuit for a semiconductor switching element is constituted by a semiconductor element and an optical data link, and a switching signal of the semiconductor switching element is externally supplied to the optical data link as an optical signal. The signal is converted into a logic level signal to operate the semiconductor element. Thus, there is no electrical connection between the drive circuit and the outside, and the semiconductor switch can be downsized.

In a semiconductor switch according to a sixth aspect of the present invention, a converter is connected in parallel with the second capacitor, and an output of the negative polarity of the converter is used as a negative power supply of a drive circuit of the semiconductor switching element. Accordingly, the semiconductor switch can have a positive power supply and a negative power supply, and can apply a negative charge at the time of turn-off.

In a semiconductor switch according to a seventh aspect of the present invention, the input circuit of the photocoupler is connected in parallel with the second capacitor, and the negative output of the photocoupler is connected to the control terminal of the semiconductor switching device. Thereby, when the semiconductor switching element is in the off state, that is, while the capacitor is being charged, the light emitting diode of the input circuit of the photocoupler emits light, and the photodiode of the output circuit generates an electromotive force. Since the negative voltage is supplied, the semiconductor switching element does not malfunction due to external noise or the like.

[0015] In the semiconductor switch according to claim 8 of the present invention, the driving circuit of each semiconductor switching element includes:
It has a negative power supply supplied from a snubber circuit of a semiconductor switching element connected to a potential lower than its own.
Accordingly, the semiconductor switch can have a positive power supply and a negative power supply, and can apply a negative charge at the time of turn-off.

In the semiconductor switch according to the ninth aspect of the present invention, the driving circuit of the semiconductor switching element has a negative power supply supplied from a voltage dividing circuit of the semiconductor switching element connected to a potential lower than its own. Accordingly, the semiconductor switch can have a positive power supply and a negative power supply, and can apply a negative charge at the time of turn-off.

In a semiconductor switch according to a tenth aspect of the present invention, a negative power supply is externally supplied to a drive circuit of the lowermost semiconductor switching element of the series-connected semiconductor switching elements. Thereby, all the semiconductor switching elements connected in series are turned off at high speed, so that the number of series semiconductor switching elements can be reduced and the size of the switch can be reduced.

In the semiconductor switch according to the eleventh aspect of the present invention, since the energy medium supplied from the outside is light and converted into electricity by the photovoltaic element, it is not necessary to ground the lowermost stage.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a first embodiment of the present invention. Normally, semiconductor elements are connected in series or in series / parallel, but only the configuration of one stage is shown because each stage has the same configuration.

In FIG. 1, a semiconductor device SW has a resistor R
s, diode Ds, and capacitors Cs1, Cs2
Are connected in parallel, the anode of a diode Dg is connected to the common terminal of the snubber capacitors Cs1 and Cs2, and one end of a capacitor Cg that supplies energy to the cathode of the diode Dg and the drive circuit GU of the semiconductor element is connected to the diode Dg. Connected.

The other ends of the capacitors Cg and Cs2 are CO
M, the power input of the drive circuit GU of the semiconductor element is connected in parallel to the capacitor Cg, and the output of the drive circuit GU is connected to the gate and the cathode terminal of the semiconductor element. Further, a voltage dividing resistor DV is connected in parallel to the semiconductor element SW in order to equalize the voltage sharing of each semiconductor element.

Next, the operation of the circuit will be described. Semiconductor element SW
Is off, the voltage between the anode and the cathode of the semiconductor element SW becomes the voltage Voff across the voltage dividing resistor DV.
Becomes In this state, the capacitors Cs1, Cs2, and Cg are charged. At this time, assuming that the parallel combined capacitance of the capacitors Cs2 and Cg is CL, the voltage Vcg across the capacitor Cg is

[0023]

Vcg = (Cs1 / (Cs1 + CL)) · Voff The energy stored in the capacitor Cg is expressed by the following equation. When the semiconductor element SW is turned on, the drive circuit GU is operated with this energy.

[0024]

Ecg = １ ／ Cg · Vcg2 When an ON signal is externally input to the drive circuit GU, the drive circuit GU turns on the semiconductor element SW. The charges of the instantaneous capacitors Cs1 and Cs2 are short-circuited and discharged by the semiconductor element SW via the resistor Rs. While the semiconductor element SW is on, the voltage Vc2 across the capacitor Cs2 becomes zero, but the presence of the diode Dg makes the capacitor Cs2.
g is not discharged and energy can be supplied to the drive circuit GU.

When an off signal is input as a switching signal to the drive circuit GU, or when a reverse voltage is applied between the anode and the cathode of the semiconductor element SW, the semiconductor element SW is turned off. From the moment the semiconductor element SW is turned off, the capacitor C is connected from the main circuit via the diodes Ds and Dg.
s, Cs2, and Cg are charged.

The above is a series of flows of charging and discharging of the capacitors Cs1, Cs2, Cg. Further, the charging of the capacitor Cg does not pass through a series resistor, so that it is sufficiently fast and does not limit the operating frequency of the switch.

As described above, according to this embodiment, there is no need to supply a control power supply for the drive circuit of the semiconductor element from an external power supply, so that the complexity around the switch body can be eliminated, and Operating frequency can be increased.

Also, depending on the specifications of the semiconductor element SW and the conditions of the external circuit, etc., it is possible to realize a snubber operation without the diode Ds and the resistor Rs. Next, a second embodiment will be described.

FIG. 2 is a block diagram of the second embodiment, in which a snubber circuit is realized by resistors and capacitors. In this case, the series resistance R
s is connected and there is a charging time constant.

However, in general, the resistance of the snubber circuit is much smaller (several tens of Ω or less) than the voltage-dividing resistance, and the charging time constant is also small. In some embodiments, there is no need to supply control power for the drive circuit of the semiconductor element from an external power supply, so that complexity around the switch main body can be eliminated and the operating frequency of the switch can be increased.

Next, a third embodiment of the present invention will be described. FIG. 3 is a configuration diagram of a third embodiment of the present invention, in which a snubber circuit is realized only by a capacitor.

In this case, since there is no charging time constant, it is not necessary to supply control power for the drive circuit of the semiconductor element from the external power supply according to the present embodiment, so that the complexity around the switch body can be eliminated. , And the operating frequency of the switch can be increased.

Next, a fourth embodiment of the present invention will be described. FIG. 4 is a configuration diagram of a drive circuit according to a fourth embodiment of the present invention. In the present embodiment, the electrical switching signal is transmitted to one side of the winding Tr # 1 of the pulse transformer Tr.
And the other winding Tr # 2 is connected to the semiconductor element SW.
gu is connected to the gate (base).

When an ON signal is input via the pulse transformer Tr, the gate drive semiconductor element SWgu turns on and the semiconductor element SW turns on. Since the pulse transformer used here only needs to transmit a drive signal having a small energy, the pulse transformer can be made much smaller than a transformer for supplying power to a drive circuit, which is required in a conventional semiconductor switch. Therefore, in this embodiment, a small semiconductor switch can be obtained.

Next, a fifth embodiment of the present invention will be described. FIG. 5 is a configuration diagram of a drive circuit according to a fifth embodiment of the present invention. In the present embodiment, when an ON signal is input by light transmitted through an optical fiber cable (not shown) from an optical signal generator (not shown) provided outside, the optical data link 10 turns on the logic level. Generate a signal.

The logic-level ON signal is converted by the logic interface 11 to a level at which the gate drive semiconductor element Swgu can be driven, and the gate drive signal required to drive the switch SW by operating the gate drive semiconductor element Swgu. Occurs.

Power is supplied to the optical data link 10 and the logic interface 11 from a power supply common to the gate drive semiconductor element Swgu through the voltage drop element Rd. In this embodiment mode, electrical connection between the gate drive circuit and the outside is unnecessary, and the size of the switch can be reduced.

Next, a sixth embodiment of the present invention will be described. FIG. 6 is a configuration diagram of a sixth embodiment of the present invention. In the present embodiment, the DC-
The DC converter 20 is connected, and its negative output is supplied as a negative power supply of the drive circuit GU.

The drive circuit GU includes two gate drive semiconductor elements Swgu1 and Swgu2 having different polarities, and the gate drive semiconductor element Swgu1 supplies an electric charge necessary for the semiconductor element SW to turn on by itself turning on. The other gate drive semiconductor element Swgu2
Plays a role of extracting charges because the semiconductor element SW is turned off by turning on itself.

It is particularly important to provide both a switch for supplying charges and a switch for extracting charges in the case where the semiconductor element SW is a transistor or a thyristor that operates with minority carriers, in order to perform a high repetition operation. It is. This is because the minority carrier element cannot be turned off by the action of the residual charge unless the charge is forcibly extracted.

As described above, according to the present embodiment, the DC-DC converter is provided, and the gate drive element for supplying a negative power to the gate circuit to turn on the semiconductor element and the gate drive element for turning off the semiconductor element are provided. Is obtained.

Next, a seventh embodiment of the present invention will be described. FIG. 7 is a configuration diagram of a seventh embodiment of the present invention. In the present embodiment, the input circuit of the photocoupler 21 for outputting a photodiode is connected in parallel with the capacitor Cg. The resistor RS is for limiting the input current of the photocoupler. The positive output of the photocoupler is connected to the common terminal COM of the drive circuit GU, and the negative output is a resistor R.
n is connected to the gate of the switch element SW through n.

In this way, when the gate drive semiconductor element Swgu1 is not operating, the light emitting diode built in the photocoupler emits light and the light is generated by the light, so that the gate of the semiconductor element SW is connected to the output of the photocoupler. A negative voltage is supplied by the voltage.

As a result, the semiconductor element SW does not unexpectedly malfunction due to external noise or the like, and the reliability is improved. Next, an eighth embodiment of the present invention will be described.

FIG. 8 is a block diagram of an eighth embodiment of the present invention. The present embodiment aims at supplying both positive and negative power to the drive circuit GU. The difference from the first embodiment is that the snubber capacitor is a capacitor C.
s1, Cs2, and Cs3. The negative power supply input of the drive circuit GU is connected to a common terminal of a lower added snubber capacitor Cs3 and a resistor Rs (not shown) through a diode Dg2. And the common terminal COM is connected in parallel with the capacitor Cg2.

In this way, since the driving circuit GU can have both positive and negative power supplies, both the gate drive semiconductor elements for turn-on and turn-off as shown in FIG. A semiconductor switch can be obtained.

In this method, since a negative power supply cannot be supplied to the drive circuit for driving the lowermost semiconductor element, the turn-off is delayed. However, if all other semiconductor elements connected in series are turned off, By appropriately selecting the relationship between the number of series semiconductor elements and the maximum off-state voltage of each semiconductor element, the off function of the switch can be achieved, so that there is no problem.

Next, a ninth embodiment of the present invention will be described. FIG. 9 is a configuration diagram of a ninth embodiment of the present invention. This embodiment is different from the first embodiment in that the voltage dividing resistor is constituted by a series connection of DV1 and DV2, and the common terminal of the lower voltage dividing resistors DV1 and DV2 is a diode DN.
This is a point connected to the gate of the switch element SW through the resistor RN.

Thus, when the driving circuit GU does not operate, a negative voltage is supplied to the gate of the semiconductor element by the shared voltage of the voltage dividing resistor DV2. As a result, the semiconductor element does not unexpectedly malfunction due to external noise or the like, and the reliability is improved.

In the eighth and ninth embodiments, a negative power supply cannot be supplied to the drive circuit for driving the lowermost semiconductor element. However, if power is supplied from the outside, the negative power supply is also supplied to the lowermost drive circuit. It becomes possible to give. Accordingly, all the switch elements connected in series are turned off at high speed, so that the number of switch elements in series can be reduced, and the size of the switch can be reduced.

Further, in this case, since the lowermost stage is normally at the ground potential, the supply of power is relatively easy even by electrical connection, and the effect of the invention is not impaired. In addition, if the optical-electrical conversion is used to supply power, the lowermost stage does not need to be grounded, so that the degree of freedom in switch design is increased, and a switch having a floating potential as a whole can be realized.

[0052]

As described above, according to the present invention, it is possible to obtain a small-sized semiconductor switch which does not require external power supply to the drive circuit and which can be operated at high repetition.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram of a fifth embodiment of the present invention.

FIG. 6 is a configuration diagram of a sixth embodiment of the present invention.

FIG. 7 is a configuration diagram of a seventh embodiment of the present invention.

FIG. 8 is a configuration diagram of an eighth embodiment of the present invention.

FIG. 9 is a configuration diagram of a ninth embodiment of the present invention.

FIG. 10 is a configuration diagram of a conventional semiconductor switch.

FIG. 11 is a configuration diagram of another conventional semiconductor switch.

[Explanation of symbols]

 SW: Semiconductor element DV: Voltage dividing resistor Rs: Snubber resistor Cs1: Snubber capacitor Cs2: Snubber capacitor Ds: Snubber diode GU: Driving circuit of semiconductor element Cg: Capacitor Dg: Diode Tr: Isolation transformer Tr # 1, Tr # 2: Insulation transformer winding SWgu: Semiconductor element SW1 to SWn: Semiconductor element DV1 to DVn: Voltage dividing resistor GU1 to GUn: Driving circuit of semiconductor element Tr1 to Trn: Insulation transformer PS: External power supply LG: Optical fiber cable 1: Control device 10: Optical data link 20: DC-DC converter 21: Photocoupler

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J055 AX02 AX23 AX44 BX16 CX00 DX02 EX07 EX11 EY01 EY03 EY07 EY10 EY12 EY14 EY28 EZ01 EZ07 EZ17 EZ51 GX01

Claims (11)

[Claims] 1. A semiconductor switch comprising: a semiconductor switching element; a snubber circuit including a resistor, a diode, and a snubber capacitor connected in parallel to the semiconductor switching element; and a driving circuit for driving the semiconductor switching element. Is constituted by a plurality of capacitors, a second capacitor is connected in parallel to one or more of the capacitors via a diode, and the second capacitor is used as a power supply of a drive circuit of the semiconductor switching element. Characteristic semiconductor switch. 2. A semiconductor switch comprising: a semiconductor switching element; a snubber circuit including a resistor and a snubber capacitor connected in parallel to the semiconductor switching element; and a driving circuit for driving the semiconductor switching element. Wherein a second capacitor is connected in parallel to one or more of the capacitors via a diode, and the second capacitor is used as a power supply for a drive circuit of the semiconductor switching element. Semiconductor switch. 3. A semiconductor switch having a semiconductor switching element, a snubber circuit including a snubber capacitor connected in parallel to the semiconductor switching element, and a driving circuit for driving the semiconductor switching element, wherein the snubber capacitor includes a plurality of capacitors. A second capacitor is connected in parallel to one or a plurality of capacitors via a diode, and the second capacitor is used as a power supply for a drive circuit of the semiconductor switching element. switch. 4. A driving circuit for the semiconductor switching element, comprising a semiconductor element and an insulating transformer, wherein a switching signal of the semiconductor switching element is applied to a primary side of the insulating transformer, and a secondary side of the semiconductor element is connected to a secondary side. 4. The semiconductor switch according to claim 1, wherein a control terminal is connected. 5. The driving circuit of the semiconductor switching device includes a semiconductor device and an optical data link, and the optical data link converts a switching signal of the semiconductor switching device into a logic level signal when the switching signal is given as an optical signal. 4. The semiconductor switch according to claim 1, wherein said semiconductor element is operated. 6. The semiconductor switching device according to claim 1, wherein an output of a negative polarity of a converter connected in parallel to said second capacitor is used as a negative power supply of a driving circuit of said semiconductor switching element. 3. The semiconductor switch according to claim 1. 7. The semiconductor device according to claim 1, wherein an input circuit of a photocoupler is connected in parallel to said second capacitor, and a negative output of said photocoupler is connected to a control terminal of said semiconductor switching element. 6. The semiconductor switch according to any one of 5. 8. A semiconductor switching device comprising: a plurality of semiconductor switching elements connected in series; a snubber circuit including a resistor, a diode, and a snubber capacitor connected in parallel to each semiconductor switching element; and a driving circuit for driving the semiconductor switching element. In a semiconductor switch, a driving circuit of each semiconductor switching element includes a negative power supply supplied from a snubber circuit of the semiconductor switching element connected to a potential lower than its own. 9. A semiconductor switching element connected in series, a snubber circuit including a resistor, a diode, and a snubber capacitor connected in parallel to each semiconductor switching element, a driving circuit for the semiconductor switching element, and a semiconductor switching element. In a semiconductor switch having a voltage dividing circuit connected in parallel with the element, the driving circuit of each semiconductor switching element has a negative polarity supplied from the voltage dividing circuit of the semiconductor switching element connected to a potential lower than its own. A semiconductor switch comprising: 10. The semiconductor switch according to claim 8, wherein the drive circuit for the lowermost semiconductor element obtains a negative power supply by energy supplied from the outside. 11. The semiconductor switch according to claim 10, wherein a medium of energy supplied from outside is light,
A semiconductor switch characterized by being converted into electricity by a photovoltaic element.