JPH0698528A - Gate power supply circuit - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a gate electric power for supplying energy to a gate drive circuit of a self-arc-extinguishing element by obtaining energy from the main circuit side without using an insulating transformer. It is to provide a supply circuit. [Configuration] Switching element 1 constituting a power conversion circuit
A series circuit composed of a first capacitor 6 and a reactor 8 connected in parallel with each other, and a series circuit composed of a first diode 7 and a second capacitor 9 connected in parallel to the reactor 8. The energy stored in the capacitor 9 of 2 is applied to the gate driving circuit 10 of the switching element.
A gate power supply circuit characterized in that the power is supplied to the gate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention utilizes a switching operation of a self-arc-extinguishing element or the like to supply gate power from a main circuit to a gate driving circuit of the self-arc-extinguishing element. -
Power supply circuit.

[0002]

2. Description of the Related Art By applying a self-arc-extinguishing element to a power converter such as an inverter device, harmonics on the power supply side and load side are suppressed, the power supply power factor is improved, and the device is downsized, etc. The advantages of Until now, we have not been able to obtain self-extinguishing elements that can withstand high voltage and large current, but recently GT
Since it has become possible to manufacture a self-arc-extinguishing element suitable for high-voltage, high-current applications such as O, application of the self-arc-extinguishing element to the field of high power has become active.

When a self-turn-off device such as a GTO is applied to a high voltage application, the problem of the drive power supply of the gate drive circuit of the self-turn-off device cannot be ignored. In particular, in the case of GTO, which is a switching element mainly used in the high power field, this is a serious problem. This is because the GTO is a current-controlled element and has a small current amplification factor at turn-off, so a very large current, which is a fraction of the main circuit current at turn-off, is applied to the GTO gate. There must be. Further, even when the GTO is turned on, it is necessary to keep the current flowing in the gate in order to reduce the conduction loss. Therefore, the power consumption of the GTO gate drive circuit reaches 100 W or more per GTO, depending on the type of GTO.

Since the GTO gate drive circuit is directly connected to the GTO cathode and gate to be driven, it is electrically placed at the same potential as the GTO cathode to be driven. When the GTOs are connected in series, the gate drive circuits of the respective GTOs are placed at different potentials, so the power supplies of the respective gate drive circuits must also have different potentials. That is, the power supply for the gate drive circuit is
Each GTO must be isolated from each other.

FIG. 12 shows an example of a GTO gate drive circuit which has been conventionally used. FIG. 12 shows one GTO among a plurality of GTOs constituting the power conversion circuit, and a snubber circuit and a gate drive circuit associated therewith.

In FIG. 12, GTO 1 is the main switching element, and diode 2 and capacitor 3 are the GTO.
1 snubber circuit to suppress the voltage rise rate of GTO1,
Reduce GTO loss at turn-off. The diode 4 is a freewheeling diode and serves as a main circuit current path in the regenerative mode. The resistor 5 is a DC balance resistor, and has a function of balancing the DC sharing voltage of each of the GTOs connected in series so as not to be affected by slight variations in the characteristics of the GTOs.

The gate of the GTO 1 is driven by the gate drive circuit 10. The on / off signal of the gate is transmitted as an optical signal by the optical fiber 11 and converted into an electric signal by an optical receiving module (not shown) in the gate drive circuit 10. Since an optical signal is used, isolation for each GTO 1 is automatically achieved for the gate on / off signal. The gate drive circuit 10 is powered by the isolation transformer 13
The high frequency power supplied from the high frequency AC power supply 14 via the rectifier 12 is rectified by the rectifier 12 to obtain DC power. The high frequency AC power supply 14 is placed in a low potential part and is commonly used by each GTO 1. The potential difference between the GTOs 1 is insulated by the insulation transformer 13 facing each GTO 1.

[0008]

However, there is a big problem in applying the prior art to a converter in which a large number of GTOs are connected in series and the DC bus voltage exceeds several tens of KV. That is, in order to send the high frequency power from the low potential portion through the insulation transformer, a large number of insulation transformers having an extremely large withstand voltage that can insulate a high voltage of tens of KV are required. is there. Such an isolation transformer not only requires a large space, but also becomes extremely expensive. Therefore, in terms of space and cost, the prior art has a problem in connecting a large number of GTOs in series and applying them to high voltage applications.

Therefore, it is an object of the present invention to omit the insulating transformer and utilize the on / off operation of the self-arc-extinguishing element to obtain the gain.
It is an object of the present invention to provide a gate power supply circuit in which the power supplied to the gate drive circuit is obtained from the main circuit.

[0010]

In order to achieve the above object, a gate power supply circuit according to claim (1) of the present invention is a first power supply circuit connected in parallel to a switching element constituting a power conversion circuit. Series circuit composed of the capacitor and the reactor, and a first diode connected in parallel to the reactor.
A series circuit including a battery and a second capacitor is provided, and energy stored in the second capacitor is supplied to a gate drive circuit of the switching element and the like.

A gate power supply circuit according to claim (2) of the present invention comprises a first capacitor, a reactor and a second diode which are connected in parallel to a switching element which constitutes a power conversion circuit. And a series circuit composed of a first capacitor and a second capacitor connected in parallel to the series circuit of the reactor and the second diode, and the energy stored in the second capacitor. Is supplied to the gate drive circuit of the switching element.

Further, a gate power supply circuit according to claim (3) of the present invention includes a series circuit including a first capacitor and a reactor connected in parallel with a switching element forming a power conversion circuit, and the reactor. A second capacitor connected in parallel with the second capacitor, and a series circuit including a first diode and a second capacitor connected in parallel with the parallel circuit of the reactor and the third capacitor. The energy stored in the gate drive circuit of the switching element is supplied to the gate drive circuit.

Furthermore, a game according to claim (4) of the present invention.
The power supply circuit includes a series circuit including a first capacitor and a reactor that are connected in parallel to a switching element that forms a power conversion circuit, and a first diode and a second capacitor that are connected in parallel to the reactor. The above-mentioned series circuit is provided, and the energy stored in the second capacitor is supplied to a gate drive circuit of the switching element or the like via a chopper circuit or a DC / DC converter circuit.

A gate power supply circuit according to a fifth aspect of the present invention is a series circuit including a first capacitor and a reactor connected in parallel with a switching element forming a power conversion circuit, and the reactor. First connected in parallel to
A series circuit consisting of a diode and a second capacitor,
A series circuit including a semiconductor switch and a resistor connected in parallel to the second capacitor is provided, and energy stored in the second capacitor is supplied to a gate drive circuit of the switching element and the like. The semiconductor switch is turned on when the voltage of the second capacitor reaches a predetermined value.

Further, a gate power supply circuit according to claim (6) of the present invention is a series circuit including a first capacitor and a reactor connected in parallel with a switching element forming a power conversion circuit, and the reactor. A series circuit composed of a first diode and a second capacitor connected in parallel with each other, one terminal of which is connected to one end of the switching element and the other terminal of which is the first diode and the second capacitor. Connected to the series connection point of the switching element, the second capacitor is charged through the resistance when the switching element is off, and the energy stored in the second capacitor is charged by the switching element. -To supply to the drive circuit.

[0016]

In the invention according to claim (1), the energy stored in the first capacitor while the switching element is off is transferred to the second capacitor via the reactor while the switching element is on. Since the predetermined energy can be stored in the second capacitor when the switching element is performing the switching operation, the energy stored in the second capacitor can be supplied to the gate drive circuit of the switching element.

In the invention according to claim (2), the energy stored in the first capacitor while the switching element is off is transferred to the second capacitor via the reactor while the switching element is on. The predetermined energy can be stored in the second capacitor during the switching operation of the switching element, and the energy stored in the second capacitor can be supplied to the gate drive circuit of the switching element. However, since an oscillating current flows through the reactor in this process, this oscillating current can be removed by the second diode connected in series with the reactor.

In the invention according to claim (3), the energy stored in the first capacitor while the switching element is off is transferred to the second capacitor via the reactor while the switching element is on. The predetermined energy can be stored in the second capacitor during the switching operation of the switching element, and the energy stored in the second capacitor can be supplied to the gate drive circuit of the switching element. However, a spike voltage appears in the reactor in this process, and this spike voltage can be removed by the third capacitor connected in parallel with the reactor.

In the invention according to claim (4), the energy stored in the first capacitor while the switching element is off is transferred to the second capacitor via the reactor while the switching element is on. When the switching element is performing a switching operation, a predetermined energy can be stored in the second capacitor. Therefore, when the energy stored in the second capacitor is supplied to the gate drive circuit of the switching element, etc., the chopper circuit Or D
By supplying the power to the gate drive circuit of the switching element via the C / DC converter circuit, it is possible to supply highly accurate and stable power to the gate drive circuit.

In the invention according to claim (5), the energy stored in the first capacitor while the switching element is off is transferred to the second capacitor via the reactor while the switching element is on. When the switching element is performing a switching operation, a predetermined energy can be stored in the second capacitor. Therefore, when the energy stored in the second capacitor is supplied to the gate drive circuit of the switching element, etc. Since the energy consumed by the gate drive circuit or the like is smaller than the energy stored in the second capacitor, the voltage of the second capacitor may gradually rise and may be overvoltage. Therefore, when the voltage of the second capacitor reaches a predetermined value, the semiconductor switch forming a series circuit including a semiconductor switch and a resistor connected in parallel to the second capacitor is turned on to turn on the second capacitor. Since energy is consumed by the resistance, overvoltage of the second capacitor can be suppressed.

In the invention according to claim (6), the energy stored in the first capacitor while the switching element is off is transferred to the second capacitor via the reactor while the switching element is on. The predetermined energy can be stored in the second capacitor when the switching element is performing the switching operation. However, since the energy stored in the second capacitor is very small when the switching element is in the off state before starting the switching operation, when the switching element is in the off state, the second capacitor is charged through the resistor and the switching element is charged. Predetermined energy can be stored in advance in the second capacitor before the switching operation of 1. is started.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG.
1)), and a snubber circuit and a freewheeler which are composed of a series circuit of a snubber diode 2 and a snubber capacitor 3.
Set the ring diode 4 and DC balance resistor 5 to GTO1.
In parallel with. Connect one end of the first capacitor 6 to the GTO
1 and the other end is connected to the node of the first diode 7. One end of the reactor 8 is connected to the anode of the first diode 7, and the other end is connected to the cathode of the GTO 1. One end of the second capacitor 9 is connected to the cathode of the first diode 7, and the other end of the second capacitor 9 is connected to the cathode of the GTO 1. The energy stored in the second capacitor 9 during the switching operation of the GTO 1 is supplied to the gate drive circuit 10. Gate drive circuit 10
Generates a gate signal by the optical signal from the optical fiber 11 and becomes a gate signal of GTO1. The operation of the gate power supply circuit of FIG. 1 configured as described above will be described with reference to FIG.

While the GTO1 is off, the first capacitor 6 is charged through the first diode 7 and the second capacitor 9 to the DC sharing voltage of the GTO1. At time point A in FIG. 2, the GTO 1 starts turning on. From time point A, the voltage VAK between the anode and cathode of GTO1 drops, and along with this, the charge of the first capacitor 6 changes from the first capacitor 6 → GTO1 → reactor 8 → first.
Is discharged in the path of the capacitor 6, and the voltage VC6 of the first capacitor 6 starts to drop. The discharge of the first capacitor 6 is finished, the voltage of the first capacitor 6 becomes zero, and the current IL8 of the reactor 8 reaches the maximum value. Then, the current of the reactor 8 charges the first capacitor 6 in the opposite direction, and the time point B is reached. At time B, the voltage of the first capacitor 6 becomes the second
Becomes equal to the voltage of the capacitor 9, the first diode 7 starts to conduct, and the current ID7 of the first diode 7 rises. When the first diode 7 is turned on, the current in the reactor 8 is the second capacitor 9 and the first capacitor 6.
It will be divided into In this state, the current ratio of the second capacitor 9 and the first capacitor 6 becomes equal to the electrostatic capacity ratio. The capacity of the second capacitor 9 is set to be much larger than that of the first capacitor 6 in order to suppress the fluctuation of the supply voltage to the gate drive circuit 10. Therefore, most of the current of the reactor 8 is the second value. Flows into the condenser 9 of.
That is, after time B, almost all the energy that the reactor 8 has flows into the second capacitor 9. At time point C, the current in the first diode 7 becomes zero.

At time point C, the first capacitor 6 is charged in the reverse direction. This energy is gradually consumed in the form of conduction loss of the GTO 1 while being exchanged with the reactor 8 after the time point C in an oscillating manner, and at the time point D, the GTO 1 turns off and the first capacitor Vibration continues until 6 is recharged. The energy Eloss consumed in the form of this loss changes the capacitance of the first capacitor 6 to C6.
, And the maximum voltage of the second capacitor 9 is Vc9, Eloss = C6. (Vc9) ² It becomes / 2. Usually, the value of Vc9 is a low value of about ten and several volts, which is suitable for the power supply voltage of the gate drive circuit 10. The energy Ec6 obtained when the first capacitor 6 is charged to the DC sharing voltage VD of GTO1 is: Ec6 = C6. (VD) ² It is / 2. From these equations, the rate of energy lost when the first capacitor 6 is reversely charged is known. If VD = 3000 [V] and Vc9 = 15 [V] as typical values, the percentage of energy lost is (Eloss / Ec6) × 100 = (Vc9 / VD) ² × 100 = (15/3000) ² X100 = 0.0025 [%] As described above, the energy loss is almost negligibly small and is not considered to be a practical problem.

However, depending on the application, the oscillating current flowing between the first capacitor 6 and the reactor 8 after the time point C may become a problem. FIG. 3 is a block diagram showing a second embodiment of the present invention made in consideration of this point. In the embodiment shown in FIG. 3, a second diode 15 is connected in series to the reactor 8 of the embodiment shown in FIG.

The operation of the second embodiment shown in FIG. 3 will be described below with reference to FIG. From time A to time C in FIG. 4, the same operation as that of the embodiment in FIG. 1 is performed. After time C, the operation differs due to the action of the second diode 15.

That is, although the first capacitor 6 is reversely charged, even if this charge is going to be discharged through the reactor 8, it is not discharged by the second diode 15 connected in series with the reactor 8. Be blocked. Therefore, the reverse charge of the first capacitor 6 is held as it is until the time D when the GTO 1 starts to turn off again, and the oscillating current does not flow. After time D, the current flowing in GTO1 is
When the first capacitor 6 is recharged by flowing with the first capacitor 6, the first diode 7 and the second capacitor 9,
The reverse charge will flow into the second capacitor 9.

In the embodiment of FIG. 1, the maximum value of the voltage applied to the reactor 8 is almost equal to the DC sharing voltage VD shared by the GTO 1. This can be explained as follows. The turn-on time of GTO1 is about 10 μs,
It is shorter than the time constant of the discharge circuit of the first capacitor 6.
Therefore, when the turn-on of GTO1 is completed, it is considered that the voltage of the first capacitor 6 maintains the charged value VD as it is while GTO1 is off. However, since the voltage applied to the reactor 8 is the voltage of the first capacitor 6 minus the voltage of the GTO1, the first voltage at the time when the turn-on of the GTO1 is completed.
The voltage of the capacitor 6 is directly applied to the reactor 8. Therefore, the voltage applied to the reactor 8 becomes maximum when the turn-on of the GTO 1 is completed, and its value is almost equal to the DC sharing voltage VD of the GTO 1. The DC shared voltage VD is usually a high voltage of about 3000 V, and the reactor that can withstand application of such a high voltage is inevitably large in size and cost.

Therefore, the third embodiment of the present invention has been devised to suppress the voltage applied to the reactor 8. FIG. 5 is a block diagram showing a third embodiment of the present invention.
In this embodiment, the reactor 8 in the embodiment of FIG.
The third capacitor 16 is connected in parallel.

The operation of the third embodiment shown in FIG. 5 will be described below with reference to FIG. At time point A in FIG. 6, the GTO
1 starts turn-on. At this time point A, the first
The capacitor 6 is charged up to the DC sharing voltage of the GTO 1, and the charge of the third capacitor 16 is zero. From time A, the voltage VAK between the anode and cathode of GTO1 starts to drop, and the charge of the first capacitor 6 is also GTO.
1 to the third capacitor 16. The difference between the voltage of the first capacitor 6 and the voltage of the third capacitor 16 is GT
Since the voltage VAK of O1 is equal to the voltage VAK of GTO1, when the voltage VAK of GTO1 becomes almost zero at the time point E, the voltages of the first capacitor 6 and the third capacitor 16 become equal to each other, and therefore the reactor 8 The voltages VL8 of the two are also equal to each other. From time point E, the charge of the first capacitor 6 is GTO
The electric charge of the first capacitor 6 is discharged as it is through the reactor 8 connected in parallel. At time point B, the discharging of the first capacitor 6 and the third capacitor 16 ends at the same time, and the voltages of the first capacitor 6 and the third capacitor 16 become zero. At time point B, the current IL8 of the reactor 8 reaches the maximum value. At time point B, the voltage of the first capacitor 6 and the third capacitor 16 becomes equal to the voltage of the second capacitor 9, and the first diode 7 starts conducting.
When the first diode 7 becomes conductive, the current of the reactor 8 is shunted to the second capacitor 9, the first capacitor 6 and the third capacitor 16. Second in this state
The current ratio of the capacitor 9, the first capacitor 6, and the third capacitor 16 is equal to the capacitance ratio. The capacitance of the second capacitor 9 is set to the first capacitor 6 and the third capacitor 9 in order to suppress the fluctuation of the supply voltage to the gate drive circuit 10.
Since it is much larger than the condenser 16 of
Most of the current in the reactor 8 flows into the second capacitor 9. That is, after time B, almost all the energy that the reactor 8 has flows into the second capacitor 9.
At time point C, the current ID7 of the first diode 7 becomes zero. At time point C, the first capacitor 6 and the third capacitor 16 are charged in opposite directions. After the time point C, this energy is gradually consumed in the form of conduction loss of the GTO 1 while being vibrationally exchanged with the reactor 8,
At time D, GTO1 turns off and the first capacitor 6
The vibration continues until is charged again.

Here, how the voltage of the reactor 8 can be suppressed by adding the third capacitor 16 will be shown. The maximum value of the voltage applied to the reactor 8 is equal to the voltage Vc16 (E) of the third capacitor 16 at the time point E, which is calculated as follows.

Since the time required for the GTO 1 to turn on is extremely short at about 10 μs, the influence of the current flowing through the reactor 8 during this period can be ignored. Therefore, the electric charge stored in the first capacitor 6 moves to the third capacitor 16 as it is, and at the time E when the turn-on of the GTO 1 is completed, the voltage of the first capacitor 6 and the third capacitor 16 It may be considered that the voltages of the two become equal to each other. Therefore,
If the charge of the first capacitor 6 at time A is Qc6 (A) and the charge of the first capacitor 6 at time E is Qc6 (E), and the charge of the third capacitor 16 is Qc16 (E), Qc6 (A) = Qc6 (E) + Qc16 (E)

However, since the charge of the capacitor is the product of the voltage and the electrostatic capacitance, the voltage of the first capacitor 6 at the time point A is set as the DC sharing voltage VD, and the voltage of the first capacitor 6 at the time point E is set. Vc6 (E), also the third capacitor 16
If the voltage of Vc16 (E) is Vd, C6 = Vc6 (E) .C6 + Vc16 (E) .C16

As already mentioned, since the difference between the voltage of the first capacitor 6 and the voltage of the third capacitor 16 is equal to the voltage of GTO1, at time E, the voltage VAK of GTO1 can be regarded as zero. Considering this, Vc6 (E) = Vc16 (E) From these two equations, Vc16 (E) = [C6 / (C16 + C6)]. VD. That is, the maximum value of the voltage applied to the reactor 8 is the same as that of the embodiment shown in FIG.
It is reduced to a value divided by 6 and the first capacitor 6. For example, if the value of the third capacitor 16 is equal to that of the first capacitor 6, the maximum value of the voltage applied to the reactor 8 is half the value of the embodiment of FIG.

However, in the third embodiment, the reactor 8
The maximum applied voltage can be suppressed, but the energy efficiency is reduced. Vc6 calculated by the previous calculation
From the values of (E) and Vc16 (E), the sum of the energy stored in the first capacitor 6 and the third capacitor 16 at time E is ETOT (E) = (C6.Vc6 (E) ² / 2) + (C16 ・ Vc16 (E) ² / 2) = (C6 · VD ² ) [C6 / (C16 + C6)] Originally, the energy stored in C6 is ETOT (A) = (C6 · VD ² / 2), it can be seen that only [C6 / (C16 + C6)] of the original energy stored at time A remains. Other energy is lost in GTO1. This loss is very small compared to the loss in the power converter total, but its effect cannot be ignored as the loss increase of GTO1. Therefore, the third embodiment can be said to be an embodiment suitable for an application in which the maximum applied voltage of the reactor 8 is desired to be suppressed, although there is no problem in that the loss of the GTO 1 is slightly increased.

In the above embodiments, the voltage of the second capacitor 9 is used as it is as the power supply voltage of the gate drive circuit 10. However, the voltage of the second capacitor 9 is about several hundreds of volts. A chopper circuit or a DC / DC converter circuit is provided between the gate drive circuit 10 and the gate drive circuit 10 to obtain a power supply having a voltage of about a dozen V which is suitable for the power supply voltage of the gate drive circuit 10. This is the fourth embodiment of the present invention shown in FIG.

The embodiment of FIG. 7 is the same as the embodiment of FIG.
DC between the second capacitor 9 and the gate drive circuit 10
A / DC converter circuit 17 is provided, and the rest of the configuration is the same as that of FIG.

The DC / DC converter circuit 17 includes a control circuit 18 to which the voltage of the second capacitor 9 is applied as an input voltage, and transistors 19a and 19b driven by the control circuit 18 when the transistor 19a is on. 19b is off, 19 when transistor 19b is on
The switching operation is alternately performed so that a is turned off, and an AC voltage is applied to the primary winding of the transformer 20. After being transformed into two suitable voltages by the transformer 20, converted into direct current by the rectifiers 21a and 21b and smoothed by the capacitors 22a and 22b, two types of isolated direct current suitable for the gate drive circuit 10 are provided. Supply as power.

At this time, the control circuit 18 monitors the output voltage of the DC / DC converter circuit 17 and controls the on / off time ratio of each of the transistors 19a and 19b so as to always maintain the predetermined voltage. Have the ability to

In the fourth embodiment, unlike the previous embodiments, two DC voltages are supplied to the gate drive circuit 10. Among the switching elements, in the case of GTO,
The gate drive circuit 10 requires two positive and negative power supplies to drive the gate to the positive side with respect to the cathode when on and to the negative side when off. The fourth embodiment is suitable for such an application.

Further, by providing the DC / DC converter circuit 17, there is an effect that the ability to cope with an abnormal situation in the power converter is enhanced. The reason for this will be described below. In the gate power supply circuit of the present invention, the DC shared voltage of the switching element stored in the capacitor serves as the original power source, so if the DC bus voltage of the power converter is lost due to some accident, The gate power must be supplied only from the energy stored in the second capacitor 9 until the accident is recovered or the operation is abandoned. When such an abnormal situation occurs, it is considered that the voltage of the second capacitor 9 is significantly reduced as compared with the normal state. When the voltage of the second capacitor 9 is supplied as it is to the gate drive circuit 10, the voltage drop of the second capacitor 9 may cause an abnormal operation of the gate drive circuit 10. However, it is already DC / D
As described when the operation of the C converter circuit 17 is described, the DC / DC converter circuit 17 controls the on / off time ratio of the internal transistors 19a and 19b so that the output voltage is kept constant. It is like this. for that reason,
If power is supplied to the gate drive circuit 10 via the DC / DC converter circuit 17, even if the voltage of the second capacitor 9 drops significantly, the DC / DC
The output voltage of the converter circuit 17 can be maintained at the same level as in normal times. Thus, DC /
By the output voltage adjusting ability of the DC converter circuit 17,
The ability of the gate power supply circuit to cope with abnormal situations is enhanced. In the fourth embodiment of the present invention, the DC / DC converter circuit 17 is provided between the second capacitor 9 and the gate drive circuit 10, but the same voltage conversion function can be achieved. Then, it goes without saying that the same effect can be obtained by using not only the DC / DC converter circuit 17 but also a chopper circuit or the like.

The voltage of the second capacitor 9 is a constant voltage on average as long as the power supplied from the first capacitor 6 and the power consumed by the gate drive circuit 10 are balanced. However, in practice, the power supplied from the first capacitor 6 fluctuates due to fluctuations in the DC sharing voltage of the switching element, errors in component constants, aging, etc., and is consumed by the gate drive circuit 10. Electric power also varies. Therefore, the power supplied from the first capacitor 6 is set to be a little higher than the power consumption of the gate drive circuit 10 in consideration of various fluctuation factors and a margin. This is because if the power supplied from the first capacitor 6 is insufficient, the voltage of the second capacitor 9 will drop, and eventually the gate drive circuit 1
This is because 0 malfunctions. For this reason, the electric power supplied from the first capacitor 6 is supplied to the gate drive circuit 10
Is set to be larger on average than the power consumed by, the voltage of the second capacitor 9 will gradually rise as it is, and will eventually deviate from the range suitable as the power supply voltage of the gate drive circuit 10. Resulting in.

The fifth embodiment of the present invention shown in FIG. 8 is the second embodiment.
This embodiment is an example in which overvoltage of the capacitor 9 is prevented. This example is the same as the second capacitor 9 in the embodiment of FIG.
A series circuit composed of a resistor 23 and a switching element 24 is connected in parallel. In the fifth embodiment shown in FIG. 8, when the semiconductor switch 24 is turned on at the time when it is determined that the voltage of the second capacitor 9 has become an overvoltage, the energy stored in the second capacitor 9 is consumed by the resistor 23. As a result, the voltage of the second capacitor 9 drops, whereby the overvoltage of the second capacitor 9 can be suppressed. As described above, the present invention provides GT
The high-voltage electrostatic energy stored in the capacitor charged to the DC sharing voltage of O1 is converted into a low-voltage energy by the switching of GTO1 itself to be used as the power source of the gate drive circuit 10. . Therefore, in the above-described embodiment, the voltage of the second capacitor 9 has a very low value before the GTO 1 starts switching.
Therefore, when the GTO 1 needs a certain voltage before starting switching, the sixth embodiment of the present invention shown in FIG. 9 may be used. In the embodiment shown in FIG. 9, a voltage divider circuit comprising resistors 25 and 26 is provided between the anode and cathode of the GTO 1 in the embodiment shown in FIG. 1, and the third diode is provided at the voltage dividing point of this voltage divider circuit. The anode of the lead 27 is connected, and the cathode is connected to one end of the second capacitor 9.

With this configuration, when a voltage is applied to the DC bus of the power conversion circuit, the resistors 25, 2
The voltage is also applied to the voltage dividing circuit constituted by 6, and the second capacitor 9 is charged from the voltage dividing circuit through the third diode 27 in the initial state. Third diode 2
In the state where the GTO 1 is turned on, 7 is inserted by the voltage dividing resistor 25 so as not to consume the power of the second capacitor 9, but the resistance value of the voltage dividing resistor 25 is extremely high. You may omit it.

In the embodiment of FIG. 1, the DC balance resistor 5 that is connected in parallel with the GTO 1 is the sixth embodiment of the present invention of FIG.
It is not included in the example. This is the resistance 2 of the voltage divider.
This is because 5 and 26 function as the DC balance resistor 5. Of course, the DC balance resistor 5 may be provided separately from the resistors 25 and 26, but if the number of parts is reduced, it becomes advantageous in terms of space and cost, and if the reliability is improved, the DC balance resistor 5 is considered. It is considered more advantageous to reduce the balance resistance 5.

FIG. 10 is a block diagram showing a seventh embodiment of the present invention. This embodiment is the fifth embodiment of the present invention shown in FIG. 8 and the sixth embodiment of the present invention shown in FIG. In this case, the resistor 26 of the voltage dividing circuit can be omitted, and the effect of the fifth embodiment of the present invention shown in FIG. 8 and the sixth embodiment of the present invention shown in FIG. 9 can be obtained. It also has the effect of the example. Also in this case, the third diode 27 may be omitted as described above.

FIG. 11 is a block diagram showing an eighth embodiment of the present invention, which is the same as the fourth embodiment of the present invention shown in FIG.
It is a combination of the sixth embodiment of the present invention shown in FIG. 9, and in this case also, the effect of the fourth embodiment of the present invention of FIG.
It also has the effects of the sixth embodiment of the present invention shown in FIG.

In the above description, an example in which a GTO is used as a switching element has been described, but the present invention does not limit the switching element to GTO, and other self-turn-off type element may be used. .

Further, in the above description, the switching element is G
Although the gate drive circuit is 10 because it is TO, the circuit to which the present invention can be applied is a gate drive circuit or the like because it can be applied to the case where the switching element is a transistor or the like.

Further, although the name of the present invention is a gate power supply circuit, the present invention can be applied to the case where the switching element is a transistor or the like as described above, and therefore, the gate power supply circuit. Also includes a circuit for controlling a switching element such as a transistor.

[0051]

As described above, according to the gate power supply circuit according to the first aspect of the present invention, the main circuit side is utilized by utilizing the switching operation of the switching element placed in the main circuit. In order to obtain energy from the, the energy stored in the first capacitor during the off period of the switching element is transferred to the second capacitor via the reactor during the on period of the switching element, and stored in this second capacitor. Since the energy used is utilized, a large number of high withstand voltage insulating transformers required in the prior art are not required, and the conversion circuit composed of self-arc-extinguishing elements can be downsized and the cost can be reduced.

According to the gate power supply circuit according to the second aspect of the present invention, in addition to the effect of the invention according to the first aspect, a reactor forming the gate power supply circuit. It is possible to suppress the oscillating current flowing in the.

Further, according to the gate power supply circuit of the present invention according to claim (3), in addition to the effect of the invention according to claim (1), a reactor constituting the gate power supply circuit. It is possible to suppress the spike voltage generated in the.

Furthermore, according to the gate power supply circuit of the present invention according to claim (4), in addition to the effect of the invention according to claim (1), a gate drive circuit for a switching element, etc. The stable energy can be supplied to.

Further, according to the gate power supply circuit of the present invention according to claim (5), in addition to the effect of the invention according to claim (1), a gate power supply circuit is constructed. The overvoltage of the second capacitor can be suppressed.

Further, according to the gate power supply circuit of claim 6 of the present invention, in addition to the effect of the invention of claim 1, a gate power supply circuit is constructed. Predetermined energy can be stored in advance in the second capacitor before the switching operation of the switching element is started.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a gate power supply circuit of the present invention.

FIG. 2 is an operation waveform diagram for explaining the operation of the gate power supply circuit shown in FIG.

FIG. 3 is a configuration diagram showing a second embodiment of a gate power supply circuit of the present invention.

FIG. 4 is an operation waveform diagram for explaining the operation of the gate power supply circuit shown in FIG.

FIG. 5 is a configuration diagram showing a third embodiment of a gate power supply circuit of the present invention.

FIG. 6 is an operation waveform diagram for explaining the operation of the gate power supply circuit shown in FIG.

FIG. 7 is a configuration diagram showing a fourth embodiment of a gate power supply circuit of the present invention.

FIG. 8 is a configuration diagram showing a fifth embodiment of a gate power supply circuit of the present invention.

FIG. 9 is a configuration diagram showing a sixth embodiment of a gate power supply circuit of the present invention.

FIG. 10 is a configuration diagram showing a seventh embodiment of a gate power supply circuit of the present invention.

FIG. 11 is a configuration diagram showing an eighth embodiment of the gate power supply circuit of the present invention.

FIG. 12 is a configuration diagram of a conventional gate power supply circuit.

[Explanation of symbols]

 1 ...... Self-extinguishing element, 2 ...... Snubber diode, 3 ...... Snubber capacitor 4 ...... Freewheeling diode, 5 ...... DC balance resistance, 6 ...... First capacitor, 7 ...... 1st diode, 8 ... reactor, 9 ... 2nd capacitor, 10 ... gate drive circuit, 11 ... optical fiber, 12 ... rectifier, 13 ... isolation transformer, 14 ... High-frequency AC power supply, 15 ... second diode, 16 ... third capacitor, 17 ... DC / DC converter circuit, 18 ... DC / DC converter control circuit, 19 ... transistor, 20 ... Transformer, 21 ... Rectifier, 22 ... Capacitor, 23 ... Resistor, 24 ... Semiconductor switch, 25 ... Dividing resistor, 26 ... Dividing resistor, 27 ... Third diode ,

Claims (6)

[Claims] 1. A series circuit composed of a first capacitor and a reactor connected in parallel to a switching element constituting a power conversion circuit, and a first diode and a second capacitor connected in parallel to the reactor. A gate power supply circuit comprising a series circuit and supplying the energy stored in the second capacitor to a gate drive circuit of the switching element and the like. 2. The gate according to claim 1, wherein a second diode is connected in series to the reactor.
Power supply circuit. 3. The gate according to claim 1, wherein a third capacitor is connected in parallel to the reactor.
Power supply circuit. 4. A series circuit composed of a first capacitor and a reactor connected in parallel to a switching element forming a power conversion circuit, and a first diode and a second capacitor connected in parallel to the reactor. A gate having a series circuit and supplying the energy stored in the second capacitor to a gate drive circuit of the switching element or the like through a chopper circuit or a DC / DC converter circuit. Power supply circuit. 5. A series circuit composed of a first capacitor and a reactor connected in parallel to a switching element forming a power conversion circuit, and a first diode and a second capacitor connected in parallel to the reactor. A series circuit including a series switch and a semiconductor switch connected in parallel to the second capacitor and a resistor is provided, and energy stored in the second capacitor is supplied to a gate drive circuit of the switching element. The gate power supply circuit is characterized in that the semiconductor switch is turned on when the voltage of the second capacitor reaches a predetermined value. 6. A series circuit composed of a first capacitor and a reactor connected in parallel to a switching element forming a power conversion circuit, and a first diode and a second capacitor connected in parallel to the reactor. The switching element is provided with a series circuit and a resistor having one terminal connected to one end of the switching element and the other terminal connected to a series connection point of the first diode and the second capacitor. A gate power supply circuit, wherein the second capacitor is charged through the resistor and the energy stored in the second capacitor is supplied to a gate drive circuit of the switching element or the like.