JP2002058259A - Inverter control module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome the problem such that a switching element is broken down due to an application of a surge voltage to the element caused by an inductance of a power line or a large action of a heat in operation. SOLUTION: An inverter control module comprises two power lines 3a and 3b oppositely disposed on both main surfaces of a ceramic board 2, three output lines 4a, 4b and 4c disposed on one main surface of the board 2, a plurality of switching elements 5 respectively mounted on the line 3 and the lines 4a, 4b and 4c, a first connecting means 6 for connecting the elements 5 on the line 3a to the lines 4a, 4b and 4c, a second connecting means 7 for connecting the elements 5 mounted on the lines 4a, 4b and 4c to the line 3b, and a heat sink 9 connected to the other main surface of the board 2 via an insulating layer 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter control module for controlling a three-phase motor or the like.

[0002]

2. Description of the Related Art Conventionally, an inverter control module for controlling a three-phase motor or the like generally includes two power lines to which DC power is supplied to one main surface of a ceramic substrate and a three-phase AC power output. A ceramic circuit board having the output lines attached thereto, the one power line and a plurality of switching elements mounted on each output line, and the switching elements mounted on the one power line and A first connecting means made of a thin metal wire for electrically connecting the output line; and a second connecting means made of a thin metal wire for electrically connecting each switching element mounted on each output line to the other power line. It is composed of

In such an inverter control module, the two power lines are connected to an external power supply, the output line is connected to a three-phase motor or the like, and a DC power of 20 A or more is supplied between the two power lines from the external power supply. By repeatedly turning on and off each switching element while shifting it little by little, three-phase AC power is supplied to a three-phase motor or the like via an output line.

The switching element is an IG
BT (Insulated Gate Bicolor)
Transistor) is generally used.

The ceramic circuit board used in the inverter control module has a metallized metal layer formed in a predetermined pattern on the surface of a ceramic substrate generally made of an aluminum oxide ceramic body, and a power line and an output line are connected to the metallized metal layer. It is formed by brazing a metal circuit board, such as copper, to be a line through a brazing material, such as silver brazing. Specifically, it is suitable for raw material powders of aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, etc. Organic binders, plasticizers, solvents, etc. to form a slurry by mixing and forming a plurality of ceramic green sheets by employing a tape forming technique such as a conventionally known doctor blade method or calender roll method. High melting of tungsten, molybdenum, etc. on the ceramic green sheet Metal powder in a suitable organic binder,
The metal paste obtained by adding and mixing the solvent is printed and applied in a predetermined pattern by employing a printing technique such as a screen printing method, and then the ceramic green sheet on which the metal paste is printed and applied in a predetermined pattern is used as necessary. The ceramic green sheet and the metal paste are sintered and integrated in a reducing atmosphere at a temperature of about 1600 ° C. to form a ceramic substrate made of an aluminum oxide ceramic body having a metallized metal layer on the surface. Finally, a metal circuit board such as copper serving as a power line or an output line is placed on the metallized metal layer adhered to the ceramic substrate with a brazing material such as silver brazing interposed therebetween and reduced. In an atmosphere, the brazing material is melted by heating to a temperature of about 900 ° C., and the metallized metal layer is It is fabricated by bonding the genus circuit board.

However, in this conventional inverter control module, two power lines have an inductance, a DC power of 20 A or more is supplied between the two power lines, and each switching element is turned on / off. When a three-phase AC power is supplied to a three-phase motor or the like via an output line by shifting the switching element little by little, the switching element is turned on and off by the inductance of the power line.
When turned off, a surge voltage higher than the rated voltage is generated. As a result, an overvoltage is applied to the switching element by the surge voltage, and the switching element is destroyed, so that the inverter control module cannot be operated stably and reliably. Had disadvantages.

Therefore, the two power lines are arranged close to each other, the directions of the currents flowing through the respective power lines are reversed, and mutual inductance is generated between the two power lines. It has been proposed to reduce the inductance that it has.

However, when two power lines are arranged close to each other, a very large current of 20 A or more flows through the power lines, and a voltage of 600 V or more is applied. A short circuit occurs on the board, which impairs the reliability of the operation of the inverter control module.

In order to solve the above-mentioned drawback, an inverter control module is disposed opposite to the ceramic substrate 32 and both main surfaces of the ceramic substrate 32 as shown in FIGS. 3 and 4, and the direction of the flowing current is reversed. Two power lines 3
3a, 33b and three output lines 34a, 34b, 34c arranged on one main surface of the ceramic substrate 32.
And a power line 33a and output lines 34a and 34 formed on one main surface of the ceramic substrate 32.
b, 34c, a plurality of switching elements 35, first connecting means 36 for connecting the switching element 35 on the power line 33a to each output line 34a, 34b, 34c, and each output line 34a, 34b,
It is conceivable to form the switching element 35 mounted on 34c with the second connection means 37 for connecting to the power line 33b formed on the other main surface of the ceramic substrate 32.

According to such an inverter control module, the two power lines 33a and 33b are opposed to each other with the ceramic substrate 32 interposed therebetween, and the directions of the currents flowing through the respective power lines 33a and 33b are reversed. Mutual inductance is efficiently generated between the two power lines 33a and 33b, and the two power lines 33a and 33b are generated by the mutual inductance.
Can be greatly reduced, thereby supplying a DC power of 20 A or more between the two power lines 33a and 33b, and turning on and off the switching elements 35 little by little to output lines 34a and 34b. , 34c to a three-phase motor or the like, a surge voltage higher than the rated voltage is generated due to the inductance of the two power lines 33a and 33b when the switching element 35 is turned on and off. And as a result, the switching element 35
And the switching element 35 is effectively prevented from being destroyed, and the inverter control module can be operated stably and reliably.

At the same time, the two power lines 33a, 3a
3b is connected to the power lines 33a and 33b because the ceramic substrate 32 having excellent insulation is interposed therebetween.
Even if a very large current of A or more is applied and a voltage of 600 V or more is applied, a discharge occurs between the power lines 33a and 33b, and no short circuit occurs between the power lines 33a and 33b. The operation of the module can be made highly reliable.

[0012]

However, in the inverter control module described above, the ceramic substrate 32 is made of an aluminum oxide ceramic body, and its thermal conductivity is as low as about 20 W / m · K. If the switching element 35 generates a large amount of heat at that time, the heat cannot be efficiently dissipated into the atmosphere via the ceramic substrate 32, and as a result, the switching element 35 emits itself. There has been a problem to be solved in that the inverter control module cannot be operated normally due to a high temperature caused by heat, thermal destruction of the switching element 35 and thermal degradation of the characteristics.

The present invention has been devised in view of the above-mentioned drawbacks, and aims at destruction of a switching element due to application of a surge voltage, discharge between two power lines, cracking of a ceramic substrate, thermal destruction of a switching element, etc. The present invention is to provide an inverter control module that can effectively prevent DC power supply and convert a DC power supply to a three-phase AC power supply reliably and for a long period of time.

[0014]

An inverter control module according to the present invention is arranged so that a ceramic substrate and two main surfaces of the ceramic substrate are opposed to each other, and the directions of flowing currents are opposite.
Power lines, three output lines arranged on one main surface of the ceramic substrate, a power line formed on one main surface of the ceramic substrate, and a plurality of power lines mounted on each output line. A switching element, first connection means for connecting the switching element on the power line to each output line, and a power line formed on the other main surface of the ceramic substrate with the switching element mounted on each output line And a radiator joined to the other main surface of the ceramic substrate via an insulating layer.

According to the inverter control module of the present invention, the two power lines are opposed to each other with the ceramic substrate interposed therebetween and the directions of the currents flowing through the respective power lines are reversed. Mutual inductance can be efficiently generated between the two power lines and the inductance of the two power lines can be greatly reduced by the mutual inductance. When three-phase AC power is supplied to a three-phase motor or the like from an output line by shifting the on / off of the elements little by little, when the switching elements are turned on and off, the rated voltage is reduced due to the inductance of the two power lines. High surge voltage does not occur,
As a result, overvoltage is applied to the switching element, and it is possible to effectively prevent the switching element from being destroyed, and to operate the inverter control module stably and reliably.

At the same time, since the two power lines have a ceramic substrate having excellent insulating properties interposed therebetween, even if a very large current of 20 A or more is applied to the power lines and a voltage of 600 V or more is applied, the power lines are not affected. A discharge is not generated between them, and a short circuit does not occur in the ceramic circuit board, whereby the operation of the inverter control module can be made highly reliable.

Further, according to the inverter control module of the present invention, since the heat radiator is bonded to the other main surface of the ceramic substrate via the insulating layer, a large number of switching elements are required when the inverter control module is operated. Even if heat is generated, the heat is efficiently dissipated into the atmosphere via the radiator, and as a result, the switching element is effectively prevented from being abnormally high in temperature, and is always at an appropriate temperature. Normal operation can be performed, and the inverter control module can be normally operated for a long period of time.

Further, according to the inverter control module of the present invention, the ceramic substrate and the insulating layer have a thermal conductivity of 6%.
When formed of a silicon nitride ceramic body having a high mechanical strength of 0 W / m · K or more and having excellent high-temperature mechanical strength, a large amount of heat generated by the switching element for operation is maintained while maintaining a high mechanical strength of the inverter control module. To the heat radiator and dissipate it more efficiently into the atmosphere via the heat radiator, whereby the inverter control module can operate normally and stably for a longer period of time.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail based on embodiments shown in the accompanying drawings. FIGS. 1 and 2 show an embodiment of an inverter control module according to the present invention, in which two power lines 3a, 3b are provided on both main surfaces of a ceramic substrate 2. FIG.
And a switching element 5 having three output lines 4a, 4b, and 4c arranged on one main surface, and a power formed on one main surface of the ceramic substrate 2. A switching element 5 on line 3a and each output line 4a, 4b, 4c.
To connect the switching element 5 on the power line 3a to each of the output lines 4a, 4b, 4c via the first connection means 6, and to mount the switching element on each of the output lines 4a, 4b, 4c. 5 to the power line 3b formed on the other main surface of the ceramic substrate 2
Is formed by connecting through the connecting means 7 of the above.

The ceramic substrate 2 of the ceramic circuit board 1 includes power lines 3a and 3b and output lines 4a and 4a.
b, 4c and power line 3a, output lines 4a, 4
It functions as a support member for supporting the switching element 5 mounted on the elements b and 4c, and is formed of a ceramic insulator such as an aluminum oxide ceramic body or a silicon nitride ceramic body.

When the ceramic substrate 2 is made of, for example, a silicon nitride ceramic body, an appropriate organic binder, a plasticizer, and a solvent are added to a raw material powder such as silicon nitride, aluminum oxide, magnesium oxide, and yttrium oxide. A ceramic green sheet (ceramic green sheet) is formed by forming a slurry and applying the slurry by a conventionally known doctor blade method or calendar roll method.
Then, the ceramic green sheet is subjected to an appropriate punching process to form a predetermined shape and, if necessary, a plurality of sheets are laminated to form a molded body. Thereafter, this is formed into a non-oxidizing material such as a nitrogen atmosphere. 1600 to 200 in atmosphere
It is manufactured by firing at a high temperature of 0 ° C.

The ceramic substrate 2 has one power line 3a and three output lines 4a on one main surface thereof.
4b and 4c, one power line 3b is brazed to the other main surface via an adhesive such as an active metal brazing material.

The power line 3a serves to supply DC power supplied from an external power supply to the switching element 5, and the output lines 4a, 4b, 4c provide three-phase AC converted by turning on / off the switching element 5. It functions to supply power to an external three-phase motor or the like.

The two power lines 3a, 3b and 3
The output lines 4a, 4b, and 4c of the book are made of a metal material such as copper or aluminum, and are subjected to a well-known metal processing method such as a rolling method or a punching method on an ingot of copper or aluminum. For example, if the thickness is 500μ
m, it is manufactured in a predetermined pattern shape.

Further, the bonding of the two power lines 3a, 3b and the three output lines 4a, 4b, 4c to the ceramic substrate 2 is performed, for example, by using a silver brazing material (silver: 72% by weight,
Activated wax obtained by adding at least one of titanium, tungsten, hafnium, and / or a hydride thereof to 2 to 5% by weight of copper: 28% by weight or aluminum brazing material (aluminum: 88% by weight, silicon: 12% by weight). Specifically, power lines 3a, 3b and output lines 4a, 4b, 4c are placed on the surface of the ceramic substrate 2 with an active metal brazing material interposed therebetween. Heat treatment is performed in a vacuum or in a neutral or reducing atmosphere at a predetermined temperature (about 900 ° C. for a silver brazing material, about 600 ° C. for an aluminum brazing material) to melt the active metal brazing material and to form the ceramic substrate 2. Surface and power lines 3a, 3b and output lines 4a, 4b, 4c
This is performed by joining the lower surface of the first and second substrates.

If the power lines 3a and 3b and the output lines 4a, 4b and 4c are formed of oxygen-free copper, the surface of the copper is present in the copper during brazing. The wettability with the active metal brazing material is improved without being oxidized by the generated oxygen, and the bonding to the ceramic substrate 2 via the active metal brazing material is strengthened. Therefore, the power lines 3a, 3b and the output lines 4a, 4b, 4c
Is preferably formed from oxygen-free copper.

The power lines 3a, 3b and the output lines 4a, 4b, 4c are formed by depositing a metal of good conductivity made of nickel, having good corrosion resistance and good wettability to a brazing material by plating. In this case, the power lines 3a, 3b and the output lines 4a, 4b, 4c are effectively prevented from being oxidized and corroded, and the switching elements 5, the external power source, and the external 3 The phase motor and the like can be connected very firmly via a brazing material such as solder. Accordingly, the power lines 3a, 3b and the output lines 4a, 4b, 4
It is preferable that a metal having good conductivity, made of nickel, and having good corrosion resistance and good wettability to a brazing material is applied to the surface thereof by plating.

The ceramic circuit board 1 also includes a power line 3a disposed on one main surface of the ceramic board 2.
A plurality of switching elements 5 are mounted on each of the output lines 4a, 4b, and 4c, and the switching elements 5 mounted on the power line 3a are connected to each output via first connecting means 6 made of a wire or the like. Lines 4a, 4b, 4c
The switching element 5 mounted on the output lines 4a, 4b, 4c is connected to a second connecting means 7 made of a wire or the like.
And is electrically connected to a power line 3b disposed on the other main surface of the ceramic substrate 2 via the.

The switching element 5 is an IGBT (In)
suled Gate Bicolor Tran
The power lines 3a, 3b are controlled by controlling the on / off of the current and by slightly turning on / off each switching element 5.
The DC power supplied from b is converted to a three-phase AC power and supplied to the output lines 4a, 4b, 4c.

The first connecting means 6 and the second connecting means 7 are made of a thin metal wire (wire) having a diameter of, for example, 300 μm, made of aluminum or an aluminum-silicon alloy, and joined by a conventionally known wire bonding method or the like. By using the technology, the switching element 5 mounted on the power line 3a and each output line 4a, 4b, 4c
And the switching element 5 mounted on the output lines 4a, 4b, 4c and the power line 3b arranged on the other main surface of the ceramic substrate 2.

In the inverter control module of the present invention, the two power lines 3a and 3b are arranged to face each other with the ceramic substrate
It is important to reverse the direction of the current flowing through a and 3b.

The two power lines 3a and 3b are opposed to each other with the ceramic substrate 2 interposed therebetween, and the direction of the current flowing through the power lines 3a and 3b can be reversed between the two power lines 3a and 3b. Mutual inductance is efficiently generated, and the generated mutual inductance greatly reduces the inductance of each of the two power lines 3a and 3b. As a result, a DC power supply of 20 A or more is provided between the two power lines 3a and 3b. When three-phase AC power is supplied from the output lines 4a, 4b, and 4c to a three-phase motor or the like while the on / off of each switching element 5 is slightly shifted,
When the power is turned on / off, no surge voltage higher than the rated voltage is generated due to the inductances of the two power lines 3a and 3b, whereby an overvoltage is applied to the switching element 5 and the switching element 5 is destroyed. Is effectively prevented, and the inverter control module can be operated stably and reliably.

At the same time, two power lines 3a, 3b
Since a very large current of 20 A or more is applied to the power lines 3a and 3b due to the ceramic substrate 2 having excellent insulating properties interposed therebetween, even if a voltage of 600 V or more is applied, discharge occurs between the power lines 3a and 3b. Occurs,
The short circuit does not occur in the ceramic circuit board 1, whereby the operation of the inverter control module can be made highly reliable.

When the thickness of the ceramic substrate 2 exceeds 2 mm, it is difficult to efficiently generate mutual inductance between the two power lines 3a and 3b. There is a risk that the mechanical strength is deteriorated and the reliability as the inverter control module is reduced. Therefore, it is preferable that the thickness of the ceramic substrate 2 be in the range of 0.2 mm to 2 mm.

When the dielectric strength of the ceramic substrate 2 is less than 10 kV / mm, a discharge is generated between the power lines 3a and 3b when the thickness of the ceramic substrate 2 becomes as thin as 0.2 mm, for example. There is a risk that a short circuit will occur in the ceramic circuit board 1. Therefore, the ceramic substrate 2 has a withstand voltage of 10 kV / m.
It is preferable to set m or more.

Further, in the inverter control module of the present invention, the insulating layer 8 is formed on the other main surface of the ceramic substrate 2.
It is important that the radiator 9 is joined through
It is preferable that the ceramic substrate 2 and the insulating layer 8 are formed of a silicon nitride ceramic body.

If a heat radiator 9 is bonded to the other main surface of the ceramic substrate 2 via an insulating layer 8, even if the switching element 5 generates a large amount of heat when the inverter control module is operated, the heat is not removed. Is efficiently radiated into the atmosphere via the heat radiator 9, and as a result, the switching element 5 is effectively prevented from being abnormally high in temperature, is always at an appropriate temperature, and the switching element 5 operates normally. Becomes possible.

The radiator 9 is made of, for example, a metal material such as copper or aluminum, and is provided on the other main surface of the ceramic substrate 2 with an insulating layer 8 made of a silicon nitride ceramic body, an aluminum oxide ceramic body, or the like interposed therebetween. Are joined.

The heat dissipating body 9 has a plate shape, a comb shape having a large number of fins, and is manufactured by rolling or grinding a copper or aluminum ingot.

The insulating layer 8 made of the silicon nitride-based ceramic body, aluminum oxide-based ceramic body, or the like is provided on the power line 3b disposed on the other main surface of the ceramic substrate 2.
The ceramic substrate 2 is formed to have a predetermined thickness by employing a thermal spraying method, a sputtering method, or the like on the other main surface of the ceramic substrate 2.

In order to join the radiator 9 to the other main surface of the ceramic substrate 2, first, an insulating layer 8 is formed on the other main surface of the ceramic substrate 2 to a predetermined thickness by a spraying method, a sputtering method, or the like. NiCr / A on the surface of the insulating layer 8
u, Ti / Pt / Au, Ti / Pd / Au and the like, and a base metal layer 8a is deposited by a vapor deposition method or a sputtering method. Finally, a heat radiator made of a metal material such as copper or aluminum is applied to the base metal layer 8a. 9 is a silver brazing material (silver: 72% by weight,
Copper (28% by weight) or aluminum brazing material (aluminum: 88% by weight, silicon: 12% by weight)
This is done by brazing.

The ceramic substrate 2 and the insulating layer 8
Is formed of a silicon nitride ceramic body, the silicon nitride ceramic body has excellent high-temperature mechanical strength and high thermal conductivity of 60 W / mk or more, and maintains high mechanical strength of the inverter control module. In addition, a large amount of heat generated by the switching element 5 for operation can be satisfactorily transmitted to the radiator 9 and can be more efficiently radiated to the atmosphere via the radiator 9. Therefore, it is preferable that the ceramic substrate 2 and the insulating layer 8 are formed of silicon nitride.

Thus, according to the inverter control module described above, the two power lines 3a, 3b are connected to an external power supply, the output lines 4a, 4b, 4c are connected to a three-phase motor or the like, and two power lines are connected from the external power supply. 2 between 3a and 3b
A three-phase AC power supply is derived from the output lines 4a, 4b, and 4c by supplying a DC power supply of 0 A or more and repeatedly turning on and off each switching element 5 little by little, thereby obtaining an inverter control module. Function.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

[0045]

According to the inverter control module of the present invention, two power lines are arranged to face each other with a ceramic substrate interposed therebetween, and the directions of currents flowing through the respective power lines are reversed. Mutual inductance can be efficiently generated between the power lines and the inductance of the two power lines can be greatly reduced by the mutual inductance, thereby supplying a DC power of 20 A or more between the two power lines. When three-phase AC power is supplied to a three-phase motor or the like from an output line by slightly shifting on / off of each switching element, a rating is given due to the inductance of the two power lines when the switching element is turned on / off. No surge voltage higher than the It takes overvoltage quenching element, stable, and it is possible to reliably operate the inverter control module to effectively prevent the switching element is broken.

At the same time, since the two power lines have a ceramic substrate having excellent insulating properties interposed therebetween, even if a very large current of 20 A or more is applied to the power lines and a voltage of 600 V or more is applied, the power lines are not affected. A discharge is not generated between them, and a short circuit does not occur in the ceramic circuit board, whereby the operation of the inverter control module can be made highly reliable.

Further, according to the inverter control module of the present invention, since the heat radiator is joined to the other main surface of the ceramic substrate via the insulating layer, a large number of switching elements are required when the inverter control module is operated. Even if heat is generated, the heat is efficiently dissipated into the atmosphere via the radiator, and as a result, the switching element is effectively prevented from being abnormally high in temperature, and is always at an appropriate temperature. Normal operation can be performed, and the inverter control module can be normally operated for a long period of time.

Further, according to the inverter control module of the present invention, the ceramic substrate and the insulating layer have a thermal conductivity of 6%.
When formed of a silicon nitride ceramic body having a high mechanical strength of 0 W / m · K or more and having excellent high-temperature mechanical strength, a large amount of heat generated by the switching element for operation is maintained while maintaining a high mechanical strength of the inverter control module. To the heat radiator and dissipate it more efficiently into the atmosphere via the heat radiator, whereby the inverter control module can operate normally and stably for a longer period of time.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of an inverter control module according to the present invention.

FIG. 2 is a cross-sectional view of the inverter control module shown in FIG.

FIG. 3 is a plan view showing a conventional inverter control module.

FIG. 4 is a sectional view of the inverter control module shown in FIG. 3;

[Explanation of symbols]

 2 ... ceramic substrate 3a, 3b ... power line 4a, 4b, 4c ... output line 5 ... switching element 6 ... ... First connecting means 7... Second connecting means 8... Insulating layer 8 a. ..... radiator

Claims (2)

[Claims] 1. A ceramic substrate, two power lines disposed opposite to both main surfaces of the ceramic substrate and having opposite directions of flowing current, and three power lines disposed on one main surface of the ceramic substrate. An output line, a power line formed on one main surface of the ceramic substrate, a plurality of switching elements mounted on each output line, and a first connecting the switching element on the power line to each output line. Connecting means for connecting the switching element mounted on each output line to a power line formed on the other main surface of the ceramic substrate;
An inverter control module, comprising: a heat radiator joined to the other main surface of the ceramic substrate via an insulating layer. 2. The inverter control module according to claim 1, wherein said ceramic substrate and said insulating layer are formed of a silicon nitride ceramic body.