JP3296409B2 - Power converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a large-capacity GTO.
The present invention relates to a power conversion device provided with a neutral point clamp inverter circuit including a (gate turn-off thyristor).

[0002]

2. Description of the Related Art Switching elements used in inverter circuits of power converters include semiconductors such as GTOs for various demands such as suppression of harmonics on a power supply side and a load side, improvement of a power supply power factor, and downsizing of a device. An element is employed. And, with the development of GTO manufacturing technology, recent GTO
Can be manufactured in a considerably large capacity.

FIG. 8 shows a PWM using such a GTO.
It is a main circuit block diagram of the NPC (neutral point clamp) inverter circuit which performs control. In this figure, AC power from an AC power supply 1 is rectified to DC by a rectifier circuit 2, and this DC power is sent to a U-phase unit 4, a V-phase unit 5, and a W-phase unit 6 via smoothing capacitors 3a and 3b. Each unit has a regenerative chopper unit 7
a and 7b are connected. Each unit 4, 5,
6 are the same, the circuit configuration of only the U-phase unit 4 is shown.

The circuit of the U-phase unit 4 includes a positive arm and a negative arm. The positive side arm includes a neutral point clamp diode 8a, GTOs 9a and 9b as switching elements, and free wheel diodes 10a and 10a.
0b, snubber diodes 11a and 11b, snubber capacitors 12a and 12b, snubber resistor 13a, regenerative diode 14a, and rapid current change di / of GTOs 9a and 9b.
It is composed of an anode reactor 15a for suppressing dt and the like. Similarly, the negative side arm includes a neutral point clamp diode 8b, a GTO 9c as a switching element,
9d, free wheel diodes 10c, 10d, snubber diodes 11c, 11d, snubber capacitors 12c,
12d, snubber resistor 13b, regenerative diode 14b,
It is composed of an anode reactor 15b and the like for suppressing a sudden current change di / dt of the GTOs 9c and 9d.

[0005] The U-phase unit 4 has a structure shown in FIG.
It is composed of two units 4a and 4b. The unit 4a houses a positive arm and other components, and the unit 4b houses a negative arm and other components. 9 and 10 show the unit 4
FIGS. 4A and 4B are views when viewed from above, and the lower side of each figure is a front opening for performing maintenance.

In FIG. 9, a water channel is provided in the unit 4a by a main pipe 16 and a branch pipe 17, and
Cools TO and other heating elements. This is G
When TO or diode performs switching operation, GTO
This is because, for example, in a 4000 kVA class inverter device, the heat loss is as large as 2 to 3 kW, and in a 10,000 kVA class inverter device, 5 to 6 kW.

The stack 18a is located at the front row of the unit 4a.
Are arranged. The stack 18a includes, in order from the left, a snubber diode 11b, a GTO 9b, a free wheel diode 10b, an insulating spacer 19, a free wheel diode 10a, a GTO 9a, a snubber diode 11
The elements arranged in a are fastened at a predetermined pressure while the water-cooled heat sink 20 is interposed therebetween. And
On the rear side of the stack 18a, the snubber capacitors 12a,
12b is provided. The electrical connection between the elements is made by buses (thin wires) 21.

[0008] Immediately behind the snubber capacitors 12a and 12b, a cooling section 22a for cooling the snubber resistor 13a is provided in the middle of the branch pipe 17.
The regenerative diode 14 is provided on the rear surface of the cooling unit 22a.
a, insulating spacer 19, neutral point clamp diode 8a
A stack 23a is provided, which is fastened at a predetermined pressure while interposing a heat sink 20 therebetween, and an anode reactor 15a cooled by a cooling unit 24a provided in the middle of the branch pipe 17 is provided on the rear surface thereof. Has been established.

The snubber circuit composed of the snubber diodes 11a and 11b and the snubber capacitors 12a and 12b is a circuit for suppressing an overvoltage change when the GTOs 9a and 9b are turned on and off. In order to suppress the rate, it is strongly required to reduce the inductance by minimizing the wiring length and loop area of the wiring connecting the circuits. Therefore G
The snubber diodes 11a, 1a are adjacent to the TOs 9a, 9b.
1b is pressed and snubber capacitors 12a and 12b are arranged in the vicinity thereof.

[0010] The unit 4b of FIG.
Since the configuration is the same as that of FIG. The reason why the unit 4 is divided into the two units 4a and 4b is that the snubber circuit must be disposed near the GTO as described above, and the insulating spacer 19 and the heat sink 20 must be attached. Stack 1 because it must be
This is because the widths of the units 8a and 23a become large, and if they are not divided, the lateral dimensions of the unit 4 become too large.

[0011]

The recent GTs
O element manufacturing technology has been remarkably developed, and recently, 6 kV-6
Large devices such as kA have been developed. Therefore, electrical equipment and structures incorporating such a large GTO element have to be large and heavy. However, when various members including GTO are incorporated in the same configuration as the conventional one, However, the above-mentioned increase in size and weight exceeds the allowable range. In particular, in the power conversion device of the 10,000 kVA class in which the NPC inverter circuit is incorporated, the following problem has occurred remarkably.

(1) Since the stacks 18a are two-dimensionally arranged in the frontmost row in front of the unit 4a, the GTO 9
When the a and 9b and the free wheel diodes 10a and 10b are out of order, the replacement work can be easily performed. However, the width of the stack 18a in the horizontal direction is inevitably large due to its configuration, and is a main cause of increasing the horizontal dimension of the unit 4a. In addition, the strength of the unit 4a was not sufficient because the lateral dimension became large.

(2) When any of the elements in the stack 18a fails, the pressurization of other healthy elements must be released, and there is a problem in the reliability of pressurization management. .

(3) As the size of the GTO element increases, it is necessary to apply a large pressure of about 8 to 10 tons to the stack 18a. However, it is not easy to obtain such a large pressure manually. Also, it has been difficult to manually apply a uniform pressure.

(4) Even if the neutral point clamp diode 8a fails and must be replaced urgently,
Since the stack 23a is disposed on the rear side of the unit 4a, each time the unit 4a must be pulled out from an inverter panel (not shown) to which the unit 4a is attached, a great deal of labor is required for the operator. Had to be forced.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a power conversion device capable of reducing the size of the device and improving maintainability, assemblability, and strength. And

[0017]

As means for solving the above-mentioned problems, the invention according to claim 1 is based on a GTO, a free wheel diode, a snubber diode, and a regenerative diode which form a neutral point clamp inverter circuit. In a power converter including a stack in which semiconductor elements are assembled in a pressurized state via a plurality of heat sink members, the GTO and the free wheel diode are assembled in the stack by applying pressure on the same axis, and attached to the GTO. The size of the GTO heat sink member to be mounted is such that the snubber diode can be attached.
The snubber diode attached to the heat sink member for O is assembled together with the regenerative diode by pressing on the same axis different from the same axis.

According to a second aspect of the present invention, in the first aspect of the present invention, the neutral point clamp inverter circuit outputs a three-phase alternating current based on inputs from positive and negative DC power supplies. Yes, the positive and negative arms of each phase are 2
And a unit is formed for each of the four stacks of each phase.

According to a third aspect of the present invention, in the second aspect of the present invention, the assembly of the GTO and the free wheel diode is disposed in the stack in front of the assembly of the snubber diode and the regenerative diode. It is characterized by having done.

According to a fourth aspect of the present invention, in the third aspect of the present invention, a neutral point clamp diode is incorporated in the assembly of the GTO and the free wheel diode.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the pressurizing means of the GTO and the free wheel diode is attached to the assembly of the GTO and the free wheel diode. , Is characterized.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, the pressurizing means is a hydraulic jack.

The invention according to claim 7 is the invention according to claim 3 or 4.
In the invention described in the above, a guide step for guiding the GTO or the free wheel diode to a predetermined mounting position from the front side of the stack is provided on the mounting surface of each heat sink member for mounting the GTO and the free wheel diode. , Is characterized.

According to an eighth aspect of the present invention, in the first aspect of the present invention, the pressurizing of the snubber diode and the regenerative diode is performed by a fastening means including a stud member. , Is characterized.

According to a ninth aspect of the present invention, in the first aspect, the neutral point clamped inverter circuit includes a snubber capacitor, the snubber capacitor, the GTO, and the snubber capacitor. And a connection bus that connects the snubber diode and the snubber diode is sandwiched through an assembly of the snubber diode and the regenerative diode.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. However, the same components as those in FIGS. 8 and 9 are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 is a configuration diagram of a unit 51 which is a main part of the present embodiment. The unit 51 is for the U-phase. As shown in FIG. 2, the U-phase unit 51 includes a V-phase unit 52, a W-phase unit 53, and a regenerative device for regenerating snubber energy to the DC power supply side. Inverter panel 5 stacked with chopper unit 54
5.

In FIG. 1, four stacks 56, 57, 58, and 59 are arranged symmetrically around a central portion in the vicinity of the front opening of the unit 51. Stack 56
And 57 correspond to the stack 18a in FIG. 9, and the stacks 58 and 59 correspond to the stack 18b in FIG. In addition, FIG.
FIG. 11 is a view of the unit 51 as viewed from above, similarly to FIG. 10, but for convenience of illustration, the stacks 56 to 59 are in an arrangement viewed from the front side.

The stacks 56 to 59 in FIG. 1 show main constituent members. The stack 56 is a GTO
9a, snubber diode 11a, freewheel diode 10a, regenerative diode 14a, etc.
0, 20A and the heat sink 60, and are assembled in a pressurized state.
b, a snubber diode 11b, a neutral point clamp diode 8a, etc. are assembled in a pressurized state via heat sinks 20, 20B. And GTO9a,
GTO heat sink 20A, 2 to which 9b is attached
Unlike the heat sink 20, the shape of OB is such that the snubber diodes 11a and 11b can be attached. Since the stacks 58 and 59 have the same configuration, description thereof will be omitted.

The unit 51 further includes snubber capacitors 12a to 12d, snubber resistors 13a and 13b, anode reactors 15a and 15b, and regenerative snubber capacitors 61a and 61b. The electrical connection and cooling of these elements are performed by the bus 21 and the main pipe 16.
And the branch pipe 17. Next, the structure of the stack 56 will be described with reference to FIGS. FIG. 3 shows the unit 5
FIG. 4 is a front view of the stack 56 as viewed from the front side of FIG.
FIG. 5 is a side view, and FIG. 5 is a view taken in the direction of arrow AA in FIG. On the base member 62, the insulating seat 63a, the heat sink 20, the free wheel diode 10a, the heat sink 20A, the GTO 9a, the heat sink 20, the insulating seat 63
b, a spring seat 64, a disc spring 65, and the like are stacked, and these are fastened by a lock nut 68 via a clamp rod 67 between the base member 62 and the lock plate 66.

A mounting plate 69 is provided above the lock plate 66, and a hydraulic jack 70 is removably mounted on the mounting plate 69 as mounting means by mounting bolts 71. Then, the base member 62
The insulating seats 63a to the disc springs 65 stacked between the lock plate 66 and the lock plate 66 are tightened by a hydraulic jack 70 at a predetermined pressure (about 8 to 10 tons).

The shape of the heat sink 20A to which the GTO 9a is attached is different from that of the heat sink 20.
A snubber diode 11a is attached behind O9a. Thus, since both the GTO 9a and the snubber diode 11a are attached to the same heat sink 20A, the electrical connection distance between the GTO 9a and the snubber diode 11a can be minimized, and the wiring inductance is minimized. Can be.

The bus 2 is located above the snubber diode 11a.
1a, insulating plate 72, bus 21b, insulating seat 63c, bus 2
1c, the regenerative diode 14a, the heat sink 60, the bush 21d, the insulating seat 63d, and the like are stacked, and these are fastened by the mounting stud 73 and the nut 74 via the leaf spring 75 at a predetermined pressure. The bus 21a connects the cathode of the snubber diode 11a and the snubber capacitor 12a, and the bus 21b connects the cathode of the GTO 9a and the snubber capacitor 12a. The bus 21b is actually attached to the heat sink 20, but there is no problem because the material of the heat sink 20 is copper which is a good conductor.

As described above, the GTO 9a, the free wheel diode 10a, and other members on these shafts are pressurized by the hydraulic jack 70 with a large force, but the snubber diode 11a and the regenerative diode 14a
It is not necessary to pressurize with a great force, and these are fastened by clamp members such as the mounting stud 73, the nut 74, and the leaf spring 75 on a shaft different from the GTO 9a and the free wheel diode 10a. ing. By pressing both the snubber diode 11a and the regenerative diode 14a together, the number of components can be reduced, and the snubber diode 11a and the regenerative diode 14a can be pressurized on a different axis from the GTO 9a and the freewheel diode 10a. Thereby, the height of the device can be suppressed and the size can be reduced.

Fastening to the snubber diode 11a and the regenerative diode 14a is performed as follows. That is, in FIG. 5, first, the right leaf spring 75 attached between the right stud 73 and the center stud 73 is tightened with a nut 74 at a predetermined pressure, and then attached between the center stud 73 and the left stud 73. The left leaf spring 75 is tightened by a nut 74 at a predetermined pressure.
In this case, since the pressing force more than twice the pressing force of the left and right studs 73 is applied to the center stud 73, each leaf spring 75
May not be uniform. But,
If a material having high rigidity is used for the mounting stud 73, the influence thereof can be avoided.

FIG. 6 is a plan view of the heat sink 20.
FIG. 7 is a view taken in the direction of arrows BB in FIG. The heat sink 20 is provided with a recess guiding step 20a formed by a semicircular portion corresponding to the post diameter of the free wheel diode 10a and a trapezoidal portion which widens from the semicircular portion by an angle θ. Therefore, the free wheel diode 10
When a is arranged at a fixed position, it is only necessary to slide the free wheel diode 10a from the front side toward the back. The heat sink 20A has substantially the same shape except for the mounting portion of the snubber diode 11a.

Next, in the stack 56, for example, G
The replacement work when the TO 9a breaks down will be described.
First, the worker uses the hydraulic jack 70 to apply a pressure to the lock plate 66 that is larger than the pressure applied during assembly to loosen the lock nut 68. Then, the pressure of the hydraulic jack 70 is released, and the pressure applied to the GTO 9a and the free wheel diode 10a is reduced to zero. Next, after inserting a dedicated jack under the GTO 9a and jacking up the GTO 9a, the failed GTO 9a is extracted. Thereafter, the operator inserts a new GTO 9a toward the home position. At this time, the recessed guide step 20Aa as described above is formed in the heat sink 20A, and the operator only has to slide the new GTO 9a toward the back. Can be. Then, after the arrangement in the home position is completed, the operator again uses the hydraulic jack 70 and performs the GTO in the reverse procedure.
9a, the free wheel diode 10a and other members are pressed.

This embodiment is substantially as described above, and has the following various advantages.

(1) Dividing the two positive and negative arms into four stacks and shortening the length of one stack facilitates uniform pressure contact with the element, so that the coefficient of thermal expansion per stack can be reduced. . Therefore, the number of disc springs can be reduced, and the stress applied to the connection bus of the main circuit can be minimized.

(2) As in the conventional case, two positive and negative arms
In the case of a stack, the overall length of one stack becomes longer, and the outer shape becomes very large. However, in this embodiment, since the stack is divided into four stacks, the space can be effectively used, and the size of the unit can be reduced.

(3) Since the GTO is arranged on the front side of the stack, when replacing the GTO, it is not necessary to pull out the unit from the inverter panel, and it is not necessary to remove the water cooling tube. Work can be performed easily.

(4) As a result of dividing the two positive and negative arms into four stacks, maintenance work only needs to be performed on the stack including the failed element, and the working time can be reduced. In addition, since there is no need to take any action other than at the failure location, the possibility of a work error is reduced, and the reliability of quality can be improved.

(5) The cooling of the GTO and the snubber diode is performed by the same water-cooled heat sink, and the connection of the snubber circuit is minimized to form a close contact structure, so that the wiring inductance can be minimized and the external dimensions of the unit can be reduced. be able to.

(6) Since a plurality of parallel-connected snubber diodes and regenerative diodes are pressurized collectively by a clamp member having three studs, the number of components can be reduced and the mounting space can be reduced. Can be.

(7) Since a detachable hydraulic jack is used as means for pressurizing the stack, a large and uniform pressing force can be obtained, and element replacement can be performed safely and reliably.

(8) Since the concave portion guiding step is formed on the heat sink, the operator can easily arrange the element at a fixed position when exchanging the element. Further, since the amount of jack-up by the hydraulic jack can be minimized, it is possible to prevent the element from being adversely affected.

(9) Since there is only one type of unit, the units of each phase can be made identical and standardized. Therefore, the number and types of spare parts prepared by the user can be reduced.

[0048]

As described above, according to the present invention, it is possible to provide a power conversion device capable of improving the maintainability, the assemblability, and the strength while reducing the size of the device.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a unit that is a main part of an embodiment of the present invention.

FIG. 2 is an explanatory view showing a state where the unit of FIG. 1 is assembled together with other units.

FIG. 3 is a front view showing a configuration of one stack in FIG. 1;

FIG. 4 is a side view of FIG. 3;

FIG. 5 is a view taken in the direction of arrows AA in FIG. 5;

FIG. 6 is a plan view of the heat sink in FIG. 3;

FIG. 7 is a view taken in the direction of arrows BB in FIG. 6;

FIG. 8 is a main circuit configuration diagram of a conventional device.

FIG. 9 is a configuration diagram of a positive arm portion of the unit in FIG. 8;

FIG. 10 is a configuration diagram of a negative arm portion of the unit in FIG. 8;

[Explanation of symbols]

 Reference Signs List 1 AC power supply 2 Rectifier circuit 3a, 3b Smoothing capacitor 4 U-phase unit 5 V-phase unit 6 W-phase unit 7a, 7b Regenerative chopper unit 8a, 8b Neutral point clamp diode 9a-9d GTO 10a-10d Free wheel diode 11a-11d Snubber diodes 12a to 12d Snubber capacitors 13a, 13b Snubber resistors 14a, 14b Regenerative diodes 15a, 15b Anode reactor 16 Main piping 17 Branch piping 18a, 18b, 23a, 23b Stack 19 Insulating spacer 20, 20A Heat sink 20a, 20Aa For recess guide Step 21 Bus 22a, 22b, 24a, 24b Cooling unit 60 Heat sink 61a, 61b Regenerative snubber capacitor 62 Base member 63a-63d Insulation seat 63 64 Spring seat 65 Countersunk 66 lock plate 67 clamp rod 68 Lock nut 69 Mounting plate 70 hydraulic jack 71 mounting bolt 72 insulating plate 73 mounting stud 74 nut 75 leaf spring

──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuhiro Sato, Inventor Kazuhiro Sato 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant (72) Kenji Kijima 1-Toshiba-cho, Fuchu-shi, Tokyo Toshiba Fuchu Plant (72) Inventor Toshiaki Matsumoto 1 Toshiba-cho, Fuchu-shi, Tokyo Toshiba Corporation Fuchu Plant (72) Toshiharu Obu 1 Toshiba-cho, Fuchu-shi, Tokyo Toshiba Corporation Fuchu Factory (56) References JP-A-7-123728 (JP, A) JP-A-8-294266 (JP, A) JP-A 8-331835 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB name) H02M 7/48

Claims (9)

(57) [Claims] 1. A GTO, a free wheel diode, a snubber diode forming a neutral point clamp inverter circuit,
And a power conversion device having a stack in which each semiconductor element of a regenerative diode is assembled in a pressurized state via a plurality of heat sink members, wherein the GTO and the free wheel diode are assembled in the stack by pressing on the same axis. , The GTO
The size of the GTO heat sink member attached to the GTO is large enough to attach the snubber diode.
A power converter, wherein a snubber diode attached to a TO heat sink member is assembled together with the regenerative diode by pressing on a same axis different from the same axis. 2. The power converter according to claim 1, wherein the neutral point clamp inverter circuit outputs a three-phase alternating current based on an input from a positive side and a negative side DC power supply. Are formed by two of the above stacks, one for each of the four stacks of each of these phases.
A power converter, wherein a unit is formed. 3. The power converter according to claim 2, wherein an assembly of the GTO and the free wheel diode is disposed in the stack on a front side of the assembly of the snubber diode and the regenerative diode. Characteristic power converter. 4. The power converter according to claim 3, wherein a neutral point clamp diode is incorporated in the assembly of the GTO and the free wheel diode. 5. The power conversion device according to claim 1, wherein the pressurizing means of the GTO and the free wheel diode comprises:
A power converter, wherein the power converter is attached to the assembly of the GTO and the free wheel diode. 6. The power converter according to claim 5, wherein said pressurizing means is a hydraulic jack. 7. The power converter according to claim 3, wherein the GTO or the free wheel diode is mounted on a mounting surface of each heat sink member on which the GTO and the free wheel diode are mounted from a front side of the stack. A power step, wherein a guide step for guiding the vehicle is provided. 8. The power converter according to claim 1, wherein the pressurization of the snubber diode and the regenerative diode is performed by a fastening unit including a stud member. Power converter. 9. The power converter according to claim 1, wherein the neutral point clamped inverter circuit includes a snubber capacitor, the snubber capacitor and the GTO, the snubber capacitor and the snubber diode. The power conversion device, wherein each connection bus for connecting the power supply device and the power supply device is sandwiched through an assembly of the snubber diode and the regenerative diode.