JPH01303066A - Power converter - Google Patents

Abstract

PURPOSE:To decrease the number of parts, by connecting snubber capacitors and snubber diodes with two GTO thyristors series-connected up and down and by using one common snubber resistance. CONSTITUTION:In a power converter furnished with a chopper circuit, a set of upper and lower GTO thyristors 1A to 1B are provided with a snubber circuit 12. Further, flywheel diodes 4A to 4B are juxtaposed with said thyristors. As the snubber circuit 12, then, the cathode side of a snubber diode 8A is connected with the cathode side of the upper GTO thyristor 1A and a snubber capacitor 10A is inserted in the cathode side of the GTO thyristor 1A. Likewise, a snubber diode 8B and a snubber capacitor 10B are also connected with the lower GTO thyristor 1B and one common snubber resistance 9 is provided between both diodes 8A, 8B. Thus, even if one of the two upper and lower GTOs gets out of order, electric current applied to the snubber resistance 9 is about twice as much as that in an ordinary case so that the safety of an apparatus becomes higher.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a power conversion device such as an inverter or a chip circuit constructed by connecting an even number of GTo thyristors in series.

(Prior Art) In general, a power converter equipped with a chopper circuit connects a DC motor 3 to a GTO thyristor 1A and 1B via a flat sliding actuator 1 and a heel 2, which are controlled to turn on and off at the same time, as shown in FIG. A flywheel diode 4 is connected in parallel to the DC motor 3.

As a power source for the GTO thyristors 1A and IB, a DC power source 5 is connected to a unit switch 6 and a filter capacitor 7.
connected via.

In a power converter equipped with such a chopper circuit, the power supplied to the DC motor 3 is controlled by switching the GTO thyristors 1A and IB, and the rotation of the motor 3 is controlled.

G engineering of a power converter using such a chopper circuit
The detailed configuration of the surroundings of the thyristors 1A and IB is shown in FIG.
9B, and snubber circuits each consisting of snubber bands 10A and 10B are connected in parallel.

In FIG. 4, a3, /iA, and 4.8 are flywheel diodes, respectively.

In a power converter equipped with such a chopper circuit, let us now consider a state in which GTO XIRISK 1Δ and IB are in the on state and the current flows from point X to point Y, resulting in flow C. Here, when the GT○ thyristors 1A and 1B are turned off, the current that had been flowing through the GTO → Noiristor 1A and 1B is changed to the X-snubber diode 8A-snubber capacitor 10A.
-Supper] - Leather 10B - Snubber diode 8B
Flows to the loop 1 of Y and snubber capacitor -10A,
10B is charged and is in an off state during ×Y.

Next, when the GTO → no-iris resistors IA and IB are turned on, the charges that were charged in the snubber capacitors 10△ and 10B are transferred to the snubber capacitors 1OA-snubber resistor 9△-GTO thyristor 1△-sunopa capacitor "j-"
Flows with 10A loop 1~, also snubber condenser +ll
0B-GT○" Noirister IB-Snubber resistor 9B-Snaper capacitor 10B flows through the loop 1" and discharges,
It is in the on state during Y.

In this way, the DC current applied between the It's about controlling.

Fig. 5 shows the circuit configuration of an LC power converter equipped with a general inverter circuit. Since it is a three-phase inverter circuit, each upper arm has three sets of GTO thyristors 1A, IB, and a flywheel diode 4A. , /
'lB is set up and each GTO thyristor IA
, 1B is configured such that output is applied to the AC motor 1 from the connection midpoint of the AC motor 1.

Note that the DC power supply 5, intermediate switch 6, and filter capacitor 7 are the same as the chopper circuit shown in FIG.

In a power converter equipped with a three-phase inverter circuit, if we consider -C for one set of upper and lower arms, the sixth
As shown in the figure, for the parallel circuit of GTO → Noisurisu 1A, 1B, flywheel diode 4A, ztl'3, the midpoint of their connection is at the output point Z, and GT○ relays 1Δ, 1B are alternately connected. On and off operation is controlled.

This inverter circuit also includes snubber diodes 8A, 8B and snubber resistor 9Δ, similar to the chopper circuit.

A snubber circuit consisting of a 9-day snubber resistor 10A and an IOB is connected in parallel, and now G and TO thyristors 1
When A is on and G D○ → Noislisk 11B is off, the current is X-G T'O thyristor 1A-7
It flows.

From this state, when GT○ thyristor 1A turns off and all GTO thyristors 1B turn on, X-snubber diode 8
/\-Snubber capacitor-10△-7's loop 1 ~ snubber capacitor 1s10△ is charged. .

Then, the current that had been flowing through the GT○ thyristor 1A until then changes to Y-
Flywheel diode/1. At the same time, the electric wire that was charging the snubber resistor 10B turns on the snubber capacitor 1B and switches on the snubber capacitor 10B. It will be discharged in the loop 1~.

Next, when the unarmed GT○ thyristor 1B turns off and the upper arm GTO thyristor 1A turns on again, the charge accumulated in the snubber capacitor 10A is transferred from the snubber capacitor 110A to the snubber resistor 9A to the GT○ thyristor 1A.
- Snubber capacitor 10A - Snubber resistor 9A route discharges, and along with this, the snubber capacitor 10 of the lower arm
B will be charged.

In this way, in an in-shell power conversion device, whether it is a chopper circuit or an inverter circuit, the subcircuits have a common configuration. Three circuit components are required for the thyristors 1A and IB: a snubber diode, a snubber resistor, and a snubber capacitor.

(Problem to be solved by invention) However, in such a conventional power conversion device, three circuit components, snubber diode, snubber resistor, and snubber content 1, are used to deal with the noise risk as described above. The higher the rating of the thyristor, the larger the capacitance is required. There were also problems in that the number of cables coming out from the parts increased, which increased restrictions on the device configuration.

In addition, the cooling tank housing the GTO Nyristor now requires a large number of bushings, and the constraints on its configuration have become significant.

Furthermore, the power converter including a chopper circuit configured by connecting two GTO thyristors vertically in series has the following problems.

In Fig. 4, during normal operation, G T-0 thyristor IA
, IB are switched at the same timing, the capacitance of the snubber capacitors 10A and 10B is C, the switching frequency is f, and the charging voltage of the snubber capacitors 10A and 10B is V, then the heat loss W of the snubber resistors 9A and 9B is W. =1/2xCV2 f (1).

Now, the lower GTO-! Considering the case where Noiristor IB has a conduction failure, the potentials of the upper GTO thyristor 1A at point 1 and Y become the same, but the upper GTO thyristor 1A has a normal potential of 2. Double the voltage will be applied, and if switching is performed in such a state, there is a high possibility that the healthy G-th thyristor 1A will also be destroyed.

However, depending on load conditions or variations in elements, there is a possibility that a healthy GTO thyristor 1A may continue to perform a normal switching operation, and in such a case, other problems may occur. In other words, if the side to the GTO thyristor 1 operates normally, the snubber capacitor 10A will be charged with a voltage of 2V, which is twice the normal voltage, and the heat loss W of the snubber resistor 9A is W = 1/2XC (2V )2 r...(2)
As a result, the heat loss W becomes four times that of normal.

Therefore, if operation continues under such conditions, the snubber resistor 9△ will become abnormally heated, which may not only destroy the resistor itself, but also damage the surrounding cables and structures. Abnormal +J11 overheated and -C, and there was a possibility that it would develop into a fire.

This invention was made in view of such conventional problems, and the snubber resistance is shared by the upper and lower GTO thyristors without providing a special snubber circuit for each of the upper and lower arms, thereby reducing the number of cables involved. The purpose of the present invention is to provide a power conversion device that can reduce the size of the device and improve reliability ↑η by reducing the number of bushings for cooling 1 ().

[Structure of the Invention] Means for Solving the Problems> The power conversion device of the present invention has G
With respect to the TO thyristor, snubber diodes, which are also connected in series above and below, are arranged in parallel in the same direction and their connection midpoints are connected to each other.
A snubber capacitor is connected between the anode of the iristor and the anode of the upper snubber diode, and the G
A snubber capacitor is connected between the cathode of the T○ thyristor and the cathode of the lower snubber diode, and a snubber resistor is connected between the connection points of these upper and lower snubber diodes and the snubber capacitor.

(Function) In the power conversion and trading of the present invention, when discharging the charges accumulated in the upper snubber capacitor and the lower snubber capacitor, the discharge is performed through a common snubber resistor. Therefore, it is not necessary to separately provide a snubber resistor in each of the snubber circuits of the upper and lower G T O4j iris, and it is possible to reduce the number of snubber resistors by one and perform the same operation as the conventional one.

(Example) Hereinafter, embodiments of the present invention will be explained based on the drawings.

Fig. 1 shows an example of this explanation, and the snubber circuit part which is connected to the GTO relay resistors IA and IB of the two lower one set is shown in the power converter equipped with the chopper circuit shown in Fig. 3. Detailed configuration is shown.

Flywheel diode 4A, /1. B are connected in parallel.

Then, as the snubber circuit 12, the cathode side of the snubber diode 8A is connected to the cathode side of the upper G TO thyristor 1△, and this G TO thyristor 1A
A snubber diode 1° is connected between the anode 1 side of the snubber diode 8A and the anode 1 side of the snubber diode 8A.

Also, connect the anode side of the snubber diode 8B to the anode side of the G-10 relay 1B on the side, and connect this 0
1-○ Connect the snubber capacitor 1 between the cathode side of the relay resistor 1B and the cathode side of the snubber tie adjuster 8B.
Connect 0B and leave it at 1.

A common snubber resistor 9 is connected between the anode side of the snubber diode 8A and the cathode side of the snubber diode 8B.

Note that the resistance value R1 and ff1tW of the snubber resistor 9 is at least twice as large as that of the conventional example.

Explaining the operation of a power converter with such a configuration, in the case of a chopper circuit, GTo on the lower side switches 1A and IB at the same time, and when both are on, current flows between X and Y. When the current flows from the on state to the off state, a current flows from X to snubber capacitor 10A to snubber diode 8A to snubber diode 8B to snubber capacitor 10B to
Charges will be accumulated in each of A and 10B.

When the G-D OI Nyristors 1A and 1B are turned on again, the snubber capacitor 10A is turned on again.

The charges accumulated in each of the 10B are discharged in the loop 1 of the snubber capacitor 10A-G ○thyristor 1 A-GTO thyristor 1B-snubber capacitor 10B-resistor 9-snubber capacitor 4-10△. Become.

In this way, conventionally '2] Ma'am each)'7
By sharing the snubber resistors 9A and 9B with one resistor 9, the number of resistors can be reduced to 1, making it possible to achieve miniaturization and simplification.

J5, where the resistance value of the snubber resistor 9 (h) is the resistance value R1 of the conventional snubber resistors 9A and 9B shown in FIG. Conventional snubber resistors 9A and 9B connected in series have the same configuration.
l) The constant τ is τ-RC, but the discharge time constant τ in the case of the snubber capacitor 10A and IOB in this embodiment is connected in series, so τ-2RC/2=RC,
The result is the same time constant.

Therefore, if a fault occurs in one of the G lower thyristors IA and IB, 1 is added.

Now, GT○thyristor 1B has failed and the upper GTOI
When the thyristor 18 (GT○thyristor 1A or Δ- if the switch continues its switching operation) state changes to the on state, the charge of the snubber capacitor 10△, which had been charged to a voltage of 2V, is transferred to the snubber capacitor 10A-GT. ○ The discharge begins to cover the loop 1 of thyristor 1Δ - snubber diode 8B - resistor 9 - snubber capacitor 10A.

Therefore, when switching continues in this state, the heat loss of the snubber resistor 9 becomes W-<1/2) 2) It will be the same as the expression.

However, the resistance value and capacitance of this snubber resistor 9 are shared between the upper and lower arms, unlike the conventional individual snubber resistors 9A and 9.
In order to stay at 1 so that it takes twice the value for B,
The heat loss W during normal switch ink operation is (1) above.
Twice the formula, that is, W=CV2 r...<4
) Therefore, the heat loss when a continuity failure occurs is only twice as much as the heat loss during normal operation, and the adverse effects caused by heating can be kept sufficiently small. In particular, in the case of resistors, it is common to use them with a glue rating, so if you use a glue rating of about 0.5, for example, the heat loss will be about 2 degrees until a failure is detected. Even if you do this, there will be no particular problem.

FIG. 2 shows another embodiment-C of the present invention, in which upper and lower G in a power converter equipped with an inverter circuit shown in FIG.
The detailed structure of one set of TO''J iris registers 1A and IB is shown in FIG.

In this embodiment as well, fly oil diodes 4A and 4B are connected in parallel to the G-O thyristors IA and 1B, which perform upper and lower switching operations of on and off alternately, forming a snubber circuit J. The snubber diodes 8A, 8B, the snubber capacitors 10Δ, 10B, and one common snubber resistor 9 are connected to the GTO thyristors IA, IB in the same way as in the sawtower circuit shown in FIG.

This embodiment differs from the embodiment shown in FIG. 1 in that the load output terminal 7 is drawn out from the connection midpoint of the G/O thyristors IA and IB.

Therefore, the lower arm GT○reelister 1A is turned on,
When the lower arm GTO thyristor 1B turns off, current flows through the X-GTO thyristors IA-Z.

Subsequently, GT○thyristor 1△ is turned off, and conversely GT
○ When Cyrisk 1B is turned on, current flows through the X-snubber capacitor 10A-snubber diode 8A-Z, and charge is accumulated in the snubber capacitor "j-10Δ."

Subsequently, when GT○ thyristor 1A is turned on again, the charge accumulated in snubber capacitor 10A is discharged through snubber capacitor 10A - GTO thyristor 1A - snubber tie auto 8B - snubber resistor 9 - snubber capacitor - 10A loop 1. It turns out.

When the GT○ thyristor 1B turns on, the charge stored in the snubber capacitor 10B is transferred to the snubber capacitor 10B - snubber resistor 9 - snubber diode 8 A - G T O thyristor 1B - snubber capacitor 10B. It will be discharged along the route.

In the case of this embodiment of the inverter circuit, the GTO thyristors IA and IB of the upper and lower arms are turned on and off alternately, and the snubber resistor 9 is a conventional snubber resistor 9A.
, 9'B, a current flows at twice the frequency (current flows).Also, the discharge time constant must be the same as in the conventional example, and the resistance value is 2W for R1.

[Effects of the Invention] As described above, according to the present invention, a snubber resistor is connected to two GT○→no-iris resistors connected in series above and below, and a snubber diode is connected to the snubber resistor. Because it connects one common thing,
Compared to the conventional example, the number of resistor parts can be reduced, and the number of lead wires connected to the resistor can also be reduced accordingly, making it possible to downsize and simplify the design. The structure can also be simplified compared to the conventional example, and the reliability of the device can be improved.

Especially when applied to a power converter equipped with a chopper circuit, even if a conduction failure occurs in one of the two upper and lower GTO thyristors, the current flowing through the snubber resistor remains the same during normal operation. Since the temperature is only about 2 degrees, there is little risk of heating accidents due to overcurrent, and safety can be improved.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a power converter equipped with a chopper circuit according to one embodiment of the present invention, FIG. 2 is a circuit diagram of a power converter equipped with an inverter circuit according to another embodiment of the present invention, and FIG. is a circuit diagram of a power conversion device equipped with a general chopper circuit, FIG. 4 is a circuit diagram of a conventional example, FIG. 5 is a circuit diagram of a power conversion device equipped with a general inverter circuit, and FIG. 6 is a circuit diagram of another power conversion device. FIG. 2 is a circuit diagram of a conventional example. 1B, IB...GTO thyristor 4A, 4B...flywheel diode 8△, 8B
・Snubber diode

Claims (1)

[Claims] With respect to the GTO thyristors connected in series in the upper and lower arms, snubber diodes, which are also connected in series in the upper and lower arms, are arranged in parallel in the same direction and their connection midpoints are connected to each other, and the anode of the GTO thyristor in the upper arm is Connect a snubber capacitor between the anode of the upper snubber diode and
A power conversion device comprising a snubber capacitor connected between the cathode of the GTO thyristor of the lower arm and the cathode of the lower snubber diode, and a snubber resistor connected between the connection points of the upper and lower snubber diodes and the snubber capacitor.