JP2000050652A - Arm structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the structure of a bridge circuit used in a DC/AC converter, or the like, especially an arm structure for suppressing the generation of inductance. SOLUTION: A current is fed from the positive (+) side of a battery 14 via a copper plate 20, an aluminum block 26 and a conductor 29 to an FET Q3 via current paths (1), (2) and (3). The current flows through the FET Q3 and a metal 32 into an aluminum block 27 via a current path (4), where the current paths (1)-(3) are mutually close to the current path (4), and the current flows in the reverse direction thus reducing the generation of inductance. The current flowing from a load through an intermediate point flows through the aluminum blocks 28, 27 and a conductor 30 into an FET Q4 via current paths (6), (7). furthermore, the current flows from the FET Q4 via a metal 37 back to the battery 14 via a current path (8), where the current paths (6)-(7) are mutually close to the current path (8) and the current flows in reverse, thus reducing the generation of inductance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a module structure of a bridge circuit used for a DC-AC inverter or the like.

[0002]

2. Description of the Related Art Today, various electric circuits are used, for example, a bridge circuit is used for a DC-AC inverter. FIG. 4 is a circuit diagram showing the configuration of such a bridge circuit, showing the configuration of one arm of the bridge circuit. For example, when driving a three-phase load, three arms are provided, and an FET (field effect transistor) Q1 is turned on by applying a gate voltage to the gate G1,
A current is supplied from a drain (D), and power is supplied from a midpoint A to a load (not shown) via a source (S). By applying a gate voltage to the gate G2, the FET Q
2 is turned on, and the current from the load flows from the drain (D) to the FET Q2 via the point A.

The diode D1 connected in parallel with the FET Q1 and the diode D2 connected in parallel with the FET Q2 are anti-parallel diodes for freewheeling current bypass.

FIG. 5 shows a conventional circuit structure for realizing the above-mentioned circuit. In the figure, in the structure of the conventional arm configuration 1, an FET Q1 (semiconductor chip on which the FET Q1 is formed) is provided on a base conductor 2a, and an FE is provided on a base conductor 2b.
TQ2 (semiconductor chip on which FET Q2 is formed) is provided, and a current is supplied to these FETs Q1 and Q2. For example, for the FET Q1, a "-" shaped copper plate 3 and a base conductor 2a are connected from a + (plus) electrode of a power supply (not shown).
Power is supplied via the. The current path at this time is as shown in FIG.

The current flowing through the FET Q1 further flows through the copper plate 5 and reaches the middle point A. This current path is shown in FIG. The current reaching the middle point A is supplied to a load (not shown) as described above. Although the mounting position of the wiring board from the midpoint A to the load is not specifically shown, the screw 6 or the screw 8
Or in other places.

On the other hand, when a current from the load is input to the above-mentioned midpoint A, on the other hand, it flows through the copper plate 7, further flows through the conductor 2b attached by the screw 8, and reaches the FET Q2. The current path at this time is shown in FIG. further,
The current flowing through the FET Q2 flows through the copper plate 9 attached to the copper plate 9 and the screws 10, and reaches a negative electrode (not shown) of a power supply (not shown). This current path is shown in FIG.
It is.

[0007]

The following problems occur in the above-described conventional circuit structure. That is, the current flowing in the arm configuration flows through the current path 1 to the arrow shown in FIG.

However, the current path is long in terms of distance. Therefore, in the conventional arm configuration, a large inductance is generated by the current flowing through the copper plate or the like, and the surge voltage is increased due to the inductance. For this reason, the switching loss of the semiconductor switching elements such as the FETs Q1 and Q2 is large, and there is a risk of breakage if a surge voltage exceeding the withstand voltage of the element occurs.

In order to solve the above problems, the present invention reduces the occurrence of inductance, reduces switching loss,
An object of the present invention is to provide a structure of an arm for preventing damage to an element.

[0010]

According to the first aspect of the present invention, there is provided a DC power supply, a first switching means for switching a current supplied from the DC power supply, and a second power supply. Switching means for supplying AC power to the load from a middle point, which is a connection point between the first and second switching means, and driving the load. A first current path up to and a second current path from the first switching means to the middle point are provided close to each other. The third current path from the second switching means to the second switching means and the fourth current path from the second switching means to the DC power supply are also provided in proximity to each other. Provide the structure of It can be achieved by the.

Here, the first and second switching means correspond to switching elements such as bipolar transistors, FETs, IGBTs (insulated gate bipolar transistors), and the middle point is the first and second switching means. , And supplies power to the load from this midpoint. Here, the load is an AC load such as a single-phase motor or a three-phase motor, and corresponds to a load such as a single-phase motor or a three-phase motor.

According to the present invention, a first current path from a DC power source such as a battery to a first switching means and a second current path from the first switching means to a middle point are provided close to each other, The configuration is such that currents in opposite directions flow through each other's current paths, thereby reducing inductance generated in the first current path and the second current path.

Further, according to the present invention, a third current path from the middle point to the second switching means and a fourth current path from the second switching means to the DC power supply are provided close to each other, The configuration is such that currents in opposite directions flow through each other's current paths, thereby reducing inductance generated in the third current path and the fourth current path.

According to a second aspect of the present invention, in the first aspect of the present invention, the first current path includes a first conductor connected to the first switching means and a first conductor connected to the first switching means. An upright first conductive block, and a first power supply conductor for supplying current from the DC power supply, wherein the second current path is a first power supply conductor attached to the first switching means.
Conductive metal fittings.

Here, the first conductive block is a conductive block made of, for example, an aluminum block, a copper block, or another conductive material. The first power supply conductor is a current path from the DC power supply to the first conductive block, and is formed of a conductor such as a copper plate or an aluminum plate. Further, the DC power supply is constituted by, for example, a battery or the like. With this configuration, the current supplied from the DC power supply is supplied to the first switching means through the first power supply conductor, the first conductive block, and the first conductor, and is formed at this time. The first current path is connected to the first switching means, and is close to a first metal fitting (second current path) through which a current flowing toward the middle point flows, and currents in opposite directions flow through both current paths. Flow and mutual induction reduce the occurrence of inductance.

According to a third aspect of the present invention, in the first aspect of the present invention, the third current path includes a second conductor connected to the second switching means, and a second current path on the second conductor. A second conductive block provided upright and a third conductive block provided on the second conductive block;
Is a second conductive fitting attached to the second switching means.

Here, the second and third conductive blocks are made of, for example, an aluminum block, a copper block, or another conductive material, similarly to the first conductive block. The second power supply conductor is a conductor connected to the-(minus) side of the DC power supply, and is made of a conductor such as a copper plate or an aluminum plate.

With this configuration, the current supplied from the middle point is supplied to the second switching means through the third conductive block, the second conductive block, and the second conductor. The formed third current path is the second current path.
Are connected to the second metal fitting (fourth current path) in which a current flowing toward the-(minus) side of the DC power supply flows, and currents in opposite directions flow in both current paths, thereby causing mutual induction. The action reduces the occurrence of inductance.

According to a fourth aspect of the present invention, in the third aspect of the present invention, a second power supply conductor is disposed between the second conductive fitting and the DC power supply. The first power supply conductor is provided close to the first power supply conductor with an insulating member interposed therebetween, and has a configuration in which currents flowing in mutually opposite directions flow.

That is, the first power supply conductor is a DC power supply +
The (positive) electrode is a conductor for receiving a power supply from the electrode and supplying a current to the first switching means. The second power supply conductor corresponds to the negative (-) side of the DC power supply, and the current flowing through the arm module. Is a conductor for returning to a DC power supply. These first and second power supply conductors are provided with an insulating member interposed therebetween, and are disposed at very close positions along the insulating member. Since the currents flowing through the second power supply conductors are also currents flowing in the opposite directions to each other, the occurrence of inductance is reduced by the mutual induction action in this case as well.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the first and second power supply conductors having the insulating member interposed therebetween are separate from the first and second switching means. is there.

With this configuration, the power supply module to be connected to the DC power supply can be created separately from the arm configuration main body, and the assembly of the two members can be facilitated to manufacture the entire arm configuration. Become.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the midpoint is located on the second conductive block, and a wiring board connected to the load extends from the second conductive block. Configuration.

In the module structure according to the first to fifth aspects, the load is connected to the wiring board extending from the third conductive block, but in the module structure according to the sixth aspect, the load is connected to the second conductive block. A load is connected from the block (middle point) by a wiring board.

With this configuration, the third current path and the fourth current path can be formed along a longer distance, and the generation of inductance can be further reduced.

[0026]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 2 is a circuit diagram of a bridge circuit used in this embodiment, for example, a bridge circuit for driving a three-phase AC motor. Since the bridge circuit used in this example drives a three-phase AC motor, three arms 12
a, 12b, and 12c, each arm 12a to 12c
The three-phase current is supplied to the motor 13 from the outputs A1 to A3 of c. The arm 12a has two FETs Q3, Q4,
And antiparallel diodes D3 and D4.
The other arms 12b and 12c have the same configuration. The arm 12b includes two FETs Q5 and Q6 and antiparallel diodes D5 and D6. The arm 12c also includes two FEs.
TQ7, Q8 and antiparallel diodes D7, D8.

When driving the motor 13, each FE
A gate signal is output to the gates G3 to G8 of TQ3 to Q8 at a predetermined timing to obtain a three-phase output from A1 to A3, and drives the motor 13.

Power is supplied to the arms 12a to 12c from the battery 14, and the arms 12a to 12c are supplied with power.
An electrolytic capacitor C is connected in parallel to .about.12c.

Next, a specific structure of one arm of the above-described bridge circuit, for example, the arm 12a is as shown in FIG. The arm 12a includes a main body of the arm 12a and a power supply unit 16, and the power supply unit 16 includes the arm 1a.
The main body 2a is covered. The power supply unit 16 is a portion surrounded by a chain line shown in FIG.

The other arms 12b and 12c also have
It is attached to the power supply unit 16 by a screw, and is arranged side by side in the direction perpendicular to the paper of FIG.

The power supply unit 16 is composed of two copper plates 20 and 21 as power supply conductors with an insulating sheet 19 interposed therebetween. The copper plate 20 is supplied with + (plus) power from the battery 14 described above, Is the battery-
(Minus) Connected to the electrode. The above-mentioned electrolytic capacitor C is disposed on the power supply unit 16 and its two terminals are connected to copper plates 20 and 21 (not shown).

The copper plate 21 connected to the minus (-) electrode is bent and extended to be longer than the copper plate 20, and is attached to the arm 12a by the screw 18 described above.

On the other hand, the arm main body 12a has two transistor modules 2 on a base 23 via an insulating sheet.
4, 25, and three aluminum blocks (hereinafter, simply referred to as aluminum blocks) 26 to 28 are provided. That is, first, conductors 29 and 30 as first and second conductors are erected on the base 23 via an insulating sheet,
An aluminum block 26 as a first conductive block is erected on a conductor 29, and an aluminum block 27 as a second conductive block is erected on a conductor 30.

At the upper end of the aluminum block 26,
This is a configuration that can be attached to the above-described copper plate 20 by screws 17, and a configuration that supplies + (plus) power to the aluminum block 26 via the copper plate 20.

On the other hand, as shown by oblique lines, the aluminum block 27 has an L-shaped cross section and is elongated in the direction perpendicular to the plane of FIG. One end of the aluminum block 27 is attached to a metal fitting 32 as a first conductive metal fitting by a screw 31. The metal fitting 32 is formed in a U-shape, for example, a copper plate. An aluminum block 28 is mounted on the aluminum block 27 as a third conductive block. Like the aluminum block 27, the aluminum block 28 is also extended in the direction perpendicular to the paper surface,
8 is fixed to the aluminum block 27 by screws (not shown). The aluminum block 28 constitutes the above-mentioned midpoint A1. For example, a wiring board is connected to the portion a in FIG.

On the other hand, the transistor module 24 incorporates, for example, an FET Q3 as first switching means provided in a portion shown by a dotted frame in FIG. Further, a snubber circuit (not shown) can be provided on the wiring board 34. The FET Q3 is provided in the wiring board 34 in the form of a semiconductor chip, for example.

Similarly, the transistor module 25
In the figure, a portion indicated by a dotted line frame has an FET Q4 as a second switching means, and has a wiring board 35 on the upper portion.
In addition, the wiring board 35 has a structure in which a snubber circuit can be provided. The FET Q4 is also provided in the wiring board 35 in the form of a semiconductor chip, for example.

The current flowing in the arm body of the above-described arm body will be described below.

When a gate signal is supplied to a gate electrode (not shown), the FET Q3 is turned on, power is supplied from the battery 14, current flows through the copper plate 20 in the direction of the arrow, and the aluminum block 26 moves downward (in the direction of the arrow). Electric current flows. The current flowing through the aluminum block 26 in the direction of the arrow is
The aluminum flows further into the conductor 29 from the aluminum block 26, and flows through the conductor 29 in the direction of the arrow (to the left in the drawing) to reach the FET Q3. Therefore, the current path (first current path) from the battery 14 to the FET Q3 is as follows.

Further, the current flowing through the FET Q 3 flows in the direction of the arrow along the metal fitting 32 of the transistor module 24, and flows into the aluminum block 27. The current that has flowed into the aluminum block 27 flows rightward on the paper, and flows into the aluminum block 28 toward the location of the midpoint electrode.
It reaches the position a of the middle point through the path of the arrow. Therefore, the current path from the FET Q3 to the middle point (second current path)
Becomes

The current flowing through the above-mentioned path is supplied to the above-mentioned motor 13 from the middle point and used for driving the motor 13. The motor 13 used in the present embodiment is a three-phase AC motor, for example, a midpoint of the FET Q5 (see FIG. 2) to be turned on next, and a midpoint of the FET Q7 (see FIG. 2) to be turned on next.・ Successively supplies three-phase currents and starts rotating.

On the other hand, the current flowing through the motor 13 is
When the gate signal is supplied to FET 4, it flows into FET Q4. This current flows from the middle point through the aluminum block 28 and directly into the lower aluminum block 27,
Further, the conductor 30 flows rightward from the aluminum block 27,
FET Q4 is reached. Therefore, the current flow at this time is the current path (third current path) shown in FIG.

Further, the current flowing through the FET Q4 flows in the direction of the arrow through the metal fitting 37 as the second conductive metal in the transistor module 25, and further flows through the copper plate 21 in the direction of the arrow to reach the negative electrode of the battery 14. .
Therefore, the current path (fourth current path) from the FET Q4 to the battery 14 is as follows.

The above current flow is performed in a cycle in which the FETs Q3 and Q4 are repeatedly turned on and off to drive the motor. For this reason, the conductors 29 and 30 in the arm 12a,
A large current flows through the aluminum blocks 26 to 28 and the like. For this reason, a large inductance usually occurs.

However, in the arm 12a of this embodiment,
As described above, the current flows through the path. Therefore, the inductance generated by the mutual induction action can be extremely reduced. For example, currents flow in opposite directions in the current path and the current path near each other, and the generated inductance can be reduced by mutual induction. In addition, currents flow in opposite directions in the current path and a position near the current path, and the inductance can be reduced by mutual induction even in this range. Further, the current path and the current path
Currents flow in mutually opposite directions at positions very close to each other with 9 therebetween, and the inductance can be reduced here as well.

As described above, according to the structure of the arm 12a of this embodiment, the generation of inductance can be suppressed as much as possible, the surge voltage can be suppressed, and the FET Q
3. Damage to the element Q4 can be prevented.

Although FIG. 1 has been described with reference to the example of the arm 12a of the three-phase bridge circuit shown in FIG. 2, the other arms 12b and 12c have the same structure, and the generated inductance is similarly reduced. In addition, it is possible to suppress the surge voltage and prevent the elements such as the FETs Q5 to Q8 from being damaged by the surge voltage. <Second Embodiment> Next, a second embodiment of the present invention will be described.

FIG. 3 is a view for explaining a specific structure of the arm of the second embodiment. Also in the present embodiment, the bridge circuit to be used is, for example, a bridge circuit for driving a three-phase AC motor. As shown in FIG.
The three arms 12a, 12b, and 12c supply three-phase power to the motor 13 from outputs A1 to A3 of the arms 12a to 12c.

That is, when driving the motor 13, each F
A gate signal is output to the gates G3 to G8 of the ETQ3 to Q8 at a predetermined timing, a three-phase output is obtained from A1 to A3, and supplied to the motor 13.

This embodiment is different from the first embodiment in that an aluminum block 39 integrally formed with the above-described aluminum blocks 27 and 28 is used, and the power supply unit 16 is attached as shown in FIG. In this configuration, the wiring board to the load (motor 13) is extended in the given direction. That is,
In this configuration, a wiring board 40 is extended in a direction indicated by an arrow b in FIG. For example, a wiring board 40 indicated by a dotted line in the figure is attached to the aluminum block 39 used in this example.

With this configuration, the current path described with reference to FIG. 1 flows in the direction indicated by the arrow に in FIG. 3 and is supplied to the load. The current flowing out of the load is supplied to the FET Q4 as a flow indicated by an arrow 'in FIG. Therefore, the flow of the current path 'is close to a part of the above-mentioned current path, and a current in the opposite direction flows in both current paths, so that the inductance can be further reduced.

The other structure of the arm is the same as that of the above-described embodiment, and the description is omitted.

As described above, in this example, the wiring board connected to the load from the middle point is provided so as to extend in the direction of the power supply unit 16, so that the current path of the current flowing in the opposite direction in the arm 12a is reduced. As a result, the occurrence of inductance can be further reduced.

Although this embodiment has been described using the example of the arm 12a, the other arms 12b and 12c have the same structure. Similarly, the generated inductance is further reduced, the surge voltage is suppressed, and the surge voltage is reduced. FET by voltage
Damage to elements such as Q5 to Q8 can be prevented.

[0056]

As described above in detail, according to the present invention, it is possible to minimize the occurrence of inductance in the arm structure and prevent an increase in surge voltage.

Further, by changing the position of the wiring board through which the current flows from the middle point to the load, the current path of the reverse current can be made longer, and the occurrence of inductance can be further reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a specific structure of an arm in the embodiment.

FIG. 2 is a circuit diagram of a bridge circuit used in the present embodiment, for example, a bridge circuit for driving a three-phase motor.

FIG. 3 is a diagram illustrating a specific structure of an arm explaining a second embodiment.

FIG. 4 is a diagram illustrating a circuit configuration of a conventional example.

FIG. 5 is a diagram illustrating a specific circuit structure of a conventional example.

[Explanation of symbols]

 12a to 12c Arm 13 Motor 14 Battery 16 Power supply unit 17, 18 Screw 19 Insulation sheet 20, 21 Copper plate 23 Insulation base 24, 25 Transistor module 26 to 28 Aluminum block 29, 30 Conductor 31 Screw 32, 37 Metal fitting 34, 35 Transistor Module 39 Aluminum block 40 Wiring board Q3-Q8 FET D3-D8 Diode

Continued on the front page F term (reference) 5H006 AA01 AA05 BB05 CA01 CA02 CA07 CA12 CA13 CB01 FA01 HA08 HA84 5H007 AA01 AA06 AA17 BB06 CA01 CA02 CB04 CB05 CC23 FA01 FA20 HA03 5H740 BA11 BA12 BB05 BB09 MM03 MM10 PP04

Claims (6)

[Claims] 1. A DC power supply, a first switching means for switching a current supplied from the DC power supply, and a second switching means.
A switching means for supplying AC power to the load from a midpoint which is a connection point of the first and second switching means, and driving the load. A first current path up to the switching means and a second current path from the first switching means to the middle point are provided in close proximity to each other, and currents in opposite directions flow through the current paths. A third current path from the point to the second switching means and a fourth current path from the second switching means to the DC power supply are provided close to each other. Arm structure characterized by the flow of air. 2. The first current path includes a first conductor to which the first switching means is connected, a first conductive block erected on the first conductor, and the DC power supply. 2. The arm of claim 1, wherein the second current path is a first conductive metal attached to the first switching means. 3. Construction. 3. The third current path comprises: a second conductor to which the second switching means is connected; a second conductive block erected on the second conductor; 3. The third conductive block provided on the conductive block of claim 3, wherein the fourth current path is a second conductive metal fitting attached to the second switching means. 4. Arm structure. 4. A second power supply conductor is provided between the second conductive fitting and the DC power supply, and the second power supply conductor and the first power supply conductor are provided with an insulating member interposed therebetween. 4. The arm structure according to claim 3, wherein currents flow in opposite directions to each other. 5. The switching device according to claim 4, wherein a portion between the first and second power supply conductors on which the insulating member is interposed is separate from the first and second switching means. Arm structure. 6. The second and third conductive blocks are integrally formed, the midpoint is located on the integrally formed conductive block, and a wiring board connected to the load is extended from the conductive block. The arm structure according to claim 1, wherein the arm is provided.