JP5696628B2 - High pressure module - Google Patents

Description

  The present invention relates to a high voltage module, and more particularly to an insulation protection mechanism for a semiconductor element protected by a gel-like insulator inside the high voltage module.

  The high-voltage module is a semiconductor device configured by sealing high-voltage semiconductor elements such as an IGBT (insulated gate bipolar transistor), a diode, a GTO (gate turn-off thyristor), and a transistor in an insulating container. In particular, the IGBT is expected to be applied to various applications because it is easy to control and can operate at a high current and a high frequency. 2. Description of the Related Art In recent years, with the increase in the capacity of IGBT elements, increasing the internal voltage of the module and increasing the density of semiconductor elements due to the increase in size and the increase in the number of chips have become issues for improving the dielectric strength inside the module.

  The internal insulation structure of a general high voltage module will be described with reference to FIG. FIG. 12 is a schematic cross-sectional view showing a configuration example of a conventional high-voltage module, and FIG. 12A and FIG. 12B show two configuration examples.

  In the high voltage module 101 shown in FIG. 12A, main functional circuit patterns are formed on the ground plate 6, the back metal substrate 3, the insulating substrate 1 made of ceramics such as alumina and aluminum nitride, and the semiconductor element 4 from the bottom. The main functional circuit surface metal substrate portion 2A and the semiconductor element 4 are stacked in this order, and the semiconductor element 4 is bonded to the main functional circuit surface metal substrate portion 2A by the bonding member 15. A DBC (Direct Bond Copper) substrate, which is a direct bonding structure, is used as the substrate portion structure including the insulating substrate 1, the front surface metal substrate portion 2A for the main functional circuit, and the back surface metal substrate 3 in order to improve thermal conductivity.

  In FIG. 12A, the main functional circuit surface metal substrate portion 2A includes an element mounting surface metal substrate 2a on which the semiconductor element 4 is mounted and relay surface metal substrates 2b and 2c. The module external terminal 8 connected to the high voltage power source 201 is connected to the relay surface metal electrode 2b via the bonding wire 10, and the relay surface metal substrate 2b is connected to the element mounting surface metal substrate 2a via the bonding wire 11. The semiconductor element 4 is mounted on the element mounting surface metal substrate 2a. The inside of the high voltage module 101 is filled with the gel insulator 5 to insulate the periphery of the high voltage component. As the gel insulator 5, for example, a silicone gel is used.

  The high-voltage module 101A shown in FIG. 12B is similar to the high-voltage module 101 shown in FIG. 12A in terms of the overall structure, but the main functional circuit surface metal substrate portion provided on the surface of the insulating substrate 1. Is different from the element mounting surface metal substrate 2a only. In the high voltage module 101A, the module external terminal 8 connected to the high voltage power supply 201 is directly connected to the element mounting surface metal electrode 2a via the bonding wire 10.

  In the high-voltage module, the reason why the gel-like insulator 5, particularly silicone gel is used for insulation is that mechanical stress due to temperature change or vibration is not applied to the bonding wires 10, 11, 12, etc. while maintaining a certain degree of mechanical strength. It can be deformed (that is, it has a low elastic modulus). However, the silicone gel itself has a lower withstand voltage in the initial state than a normal solid insulator, and the insulation performance immediately decreases with the occurrence of partial discharge (hereinafter also referred to as “PD” (Partial discharge)). Has drawbacks. The latter is because, in the silicone gel, a void is generated on the interface between the silicone gel and the insulating substrate due to the occurrence of partial discharge, and the void becomes a new insulation defect. If partial discharge is continuously generated in the gap, the dielectric breakdown is finally reached.

  As such high voltage module insulation protection technology, (1) optimization of substrate arrangement, (2) high voltage coating, and (3) optimization of gel-like insulator material for filling have been proposed. Yes. Examples of these are shown below.

(1) Optimization of substrate arrangement (see Patent Document 1).
The configuration disclosed in Patent Document 1 uses a structure in which the distance from the end of the metal substrate to the end of the insulating substrate is matched between the front and back metal substrates for the metal substrates installed on the front and back surfaces of the insulating substrate. . By using this structure, since the electric field concentration at the end of the metal substrate is relaxed, there is an effect that the partial discharge start voltage and the dielectric breakdown voltage are increased.

(2) Coating of the high pressure part (see Patent Document 2).
In the configuration disclosed in Patent Document 2, the end portion of the insulating substrate is coated with a resin and then filled with silicone gel. With this structure, the end portion of the insulating substrate is protected with a resin having a higher withstand voltage than silicone gel. Furthermore, if the dielectric constant of the resin to be coated is made higher than that of the silicone gel, the electric field strength itself at the edge of the insulating substrate can be lowered. With the above operation, the partial discharge start voltage and the dielectric breakdown voltage are increased.

(3) Optimization of the gel-like insulating material for filling (see Patent Document 3).
In the configuration disclosed in Patent Document 3, a silicone gel whose base polymer has a weight average molecular weight of 30000 to 40000 is used. If the weight average molecular weight is less than 30000, the strength is insufficient and voids and cracks are likely to occur, and if it exceeds 40000, the viscosity increases and the workability becomes poor. From the above-described actions, the use of silicone gel that is less likely to cause insulation defects produces an effect that the insulation performance (partial discharge start voltage, dielectric breakdown voltage) increases.

JP 2001-332823 A JP 2000-91472 A JP 2010-34151 A

  The above-described prior art is a technique for preventing dielectric breakdown by not generating partial discharge inside the high-voltage module, and is not a technique for preventing dielectric breakdown after the occurrence of partial discharge. As described above, in a gel-like insulator such as silicone gel, an insulation deterioration portion (void) is generated due to the occurrence of partial discharge, and thereafter, this insulation deterioration portion becomes a new insulation defect, and the insulation performance is immediately reduced. In other words, a module in which partial discharge occurred even once due to sudden events such as instantaneous high voltage, impact, heating, etc. or changes in gel properties over time may cause partial discharge even if the voltage level decreases, If it continues to be used as it is, there is a possibility of eventually leading to dielectric breakdown.

  For this reason, the present invention provides a high voltage module having a mechanism for detecting a partial discharge generated in a gel-like insulator in the high voltage module and preventing dielectric breakdown in the main functional circuit of the high voltage module. For the purpose.

  In order to achieve the above object, the present inventor, on the surface and the back surface of the insulating substrate 1 as shown in FIG. And the semiconductor element 4 is mounted on the element mounting surface metal substrate 2a of the main functional circuit surface metal substrate portion 2A, and the element mounting surface metal substrate 2a and the back metal substrate 3 are respectively connected to a high-voltage power source and A mechanism for generating partial discharge in a high voltage module in which the insulating substrate 1, the front surface metal substrate portion 2A for the main functional circuit, the back surface metal substrate 3 and the semiconductor element 4 are sealed with the gel insulator 5 was connected to the ground potential. .

  FIG. 1 is a schematic cross-sectional view showing a location where partial discharge occurs in a gel-like insulator in a high-voltage module. In FIG. 1, a front surface metal substrate 2 and a back surface metal substrate 3 are bonded to the front surface and the back surface of an insulating substrate 1, respectively, and a semiconductor element 4 is mounted on the front surface metal substrate 2 via a bonding member 15. The substrate 3 is bonded to a ground plate 6 extending to at least the outer peripheral side of the back surface metal substrate 3, and the insulating substrate 1, the front surface metal substrate 2, the back surface metal substrate 3, and the semiconductor element 4 are sealed with a gel insulator 5. A high-pressure module 101B is shown. A high voltage power supply (not shown) is connected to the semiconductor element 4 mounted on the surface metal substrate 2 in the high voltage module 101B through the bonding wire 13.

  In the gel-like insulator 5 of the high-voltage module 101B, as shown in FIG. 1, the periphery of the bonding wire 13 (A1 portion), the intersection of the surface metal substrate 2, the insulating substrate 1, and the gel-like insulator 5 (triple point) (A2 portion) ), Electric field concentration occurs at the intersection (triple point) (part A3) of the back metal substrate 3, the insulating substrate 1, and the gel insulator 5, and these are the main starting points of partial discharge. Of these, the periphery of the bonding wire 13 (A1 portion) has no ground potential portion around the wire 13 that becomes a high voltage, and therefore, the possibility of progressing to dielectric breakdown is small. In addition, the intersection (triple point) (part A3) of the back metal substrate 3, the insulating substrate 4, and the gel insulator 5 is likely to progress to dielectric breakdown because the back metal substrate 3 itself is at ground potential. Is small. Therefore, as a cause of dielectric breakdown of the high voltage module, it is particularly necessary to pay attention to partial discharge generated from the intersection (triple point) (part A2) of the surface metal substrate 2, the insulating substrate 1, and the gel insulator 5. .

  The object of examination is the intersection (triple point) (part A2) of the surface metal substrate 2, the insulating substrate 1 and the gel insulator 5 around the metal substrate, the back metal substrate 3, the insulating substrate 1 and the gel insulator 5 Focusing on the intersection (triple point) (part A3), if the bonding of the metal substrate and the removal of burrs around the substrate are sufficiently performed, the portion around the metal substrate where the electric field strength is maximum is the partial discharge. It becomes an occurrence point.

  Intersection (triple point) of this surface metal substrate 2, insulating substrate 1 and gel insulator 5 (part A2), and intersection (triple point) of back metal substrate 3, insulating substrate 1 and gel insulator 5 (triple point) ( It is difficult to directly detect the partial discharge generated in (A3 part) with a sensor. The reason for this is that in the case of a sensor based on sound or light, there is a possibility that partial discharge occurs over the entire circumference of the metal substrate, so the sensor must be mounted over a wide area. Since the current flowing by the operation is a high frequency and a large current, it is difficult to detect the discrimination of the minute high frequency current of the partial discharge.

  Therefore, in the present invention, the high voltage module is configured as shown in FIG. FIG. 2 is a schematic cross-sectional view illustrating the basic configuration of a high-pressure module according to the present invention. As shown in FIG. 2, in the high voltage module 101C, the element mounting surface metal substrate 2a is bonded to the surface of the insulating substrate 1 as the main functional circuit surface metal substrate portion, and the element mounting surface metal substrate 2a is bonded to the bonding member. 15, the semiconductor element 4 is disposed, the back surface metal substrate 3 is bonded to the back surface of the insulating substrate 1, and the back surface metal substrate 3 includes a main function substrate portion 102 configured to be connected to the ground potential. In addition to the substrate unit 102, a partial discharge generating substrate unit 103 is provided. Further, the inside of the high voltage module 101 </ b> C is filled with the gel insulator 5 to insulate the periphery of the high voltage component.

  In the high-voltage module 101C shown in FIG. 2, the main functional circuit surface metal substrate portion provided on the surface of the insulating substrate 1 in the main functional substrate portion 102 is composed of only the element mounting surface metal substrate 2a. This corresponds to the high voltage module 101A shown in FIG. On the other hand, on the surface of the insulating substrate 1 in the main functional substrate 102, in addition to the element mounting surface metal substrate 2a, other metal substrates such as relay surface metal substrates 2b and 2c as shown in FIG. May be provided, in which case the surface metal substrate portion for the main functional circuit is constituted by the element-mounting surface metal substrate 2a and the other surface metal substrate.

  In FIG. 2, a high-voltage power supply 201 is connected to the element mounting surface metal substrate 2 a in the main functional board portion 102 via the bonding wire 10, and the element mounting surface metal substrate 2 a has the highest potential in the main function board portion 102. It is a high conductor part. Further, the voltage from the high-voltage power supply 201 is also applied to the partial discharge generating substrate unit 103. Note that a high voltage of, for example, about 1700 V or more is applied from the high voltage power supply 201, but the voltage level of the applied voltage from the high voltage power supply 201 is not limited to this.

  The partial discharge generating substrate unit 103 is configured by bonding the front surface metal substrate 103b to the surface of the insulating substrate 103a and bonding the back surface metal substrate 103c to the back surface of the insulating substrate 103a. A partial discharge detection mechanism 103 d is arranged on the front surface metal substrate 103 b side, and the back surface metal substrate 103 c is connected to the ground plate 6. The high-voltage power supply 201 is connected to the surface metal substrate 103 b in the partial discharge generating substrate portion 103 through the bonding wire 14.

In addition, the arrangement configuration of the partial discharge detection mechanism 103d in the partial discharge generation substrate unit 103 is not limited to the configuration mounted on the surface metal substrate 103b as shown in FIG.
Further, the insulating substrate 103a of the partial discharge generating substrate unit 103 may be a separate component as shown in FIG. 2 with the insulating substrate 1 of the main functional substrate unit 102, or may be an integral component. . In addition, the back surface metal substrate 103c of the partial discharge generating substrate portion 103 may be a separate component member as shown in FIG. 2 with the back surface metal substrate 3 of the main functional substrate portion 102, or an integral component member. Also good. On the other hand, the surface metal substrate 103b of the partial discharge generating substrate portion 103 is a separate structure electrically separated from the main functional circuit surface metal substrate portion including the element mounting surface metal substrate 2a in the main functional substrate portion 102. A member.

  The maximum electric field strength in the partial discharge generating substrate portion 103 is designed to be about 10 to 30% larger than the maximum electric field strength in the main functional substrate portion 102, and the partial discharge generated in the partial discharge generating substrate portion 103 is reduced. Detection is performed by the partial discharge detection mechanism 103d. When partial discharge occurs in the partial discharge generating substrate 103 and is detected by the partial discharge detection mechanism 103d, based on the partial discharge detection signal from the partial discharge detection mechanism 103d, for example, power conversion in which the high voltage module 101C is mounted It is possible to take measures such as issuing an alarm on the system side such as an apparatus and preventing the influence on the system by replacing the high-voltage module 101C with a new one.

Next, the “partial discharge generating substrate portion” in the present invention will be further described.
In the partial discharge generating substrate unit 103, the maximum electric field strength needs to be larger by about 10 to 30% than the maximum electric field strength in the main functional substrate unit 102 as described above. For this reason, the main functional substrate unit 102 is configured such that, for example, the positions of the end portions of the front surface metal substrate and the back surface metal substrate coincide with each other so that the maximum electric field value at the triple point is minimized.

  3 to 4 are schematic cross-sectional views illustrating the change in electric field strength when the position of at least one of the front surface metal substrate 2 and the back surface metal substrate 3 is changed. Here, 1 is an insulating substrate, 2 is a front surface metal substrate, 3 is a back surface metal substrate, and 6 is a ground plate. As shown in FIG. 3, the maximum electric field strength is changed by shifting the end positions of the front surface metal substrate 2 or the back surface metal substrate 3 from each other. For example, when the end position in the state where the end positions of the front surface metal substrate 2 and the back surface metal substrate 3 are matched as shown in FIG. 3A is set as the reference position, the front surface as shown in FIG. If the end position of the metal substrate 2 is protruded from the reference position to the end side, the electric field strength on the front surface side decreases and the electric field strength on the back surface side increases. If the end position of the back surface metal substrate 3 protrudes from the reference position to the end side as shown in FIG. 3C, the electric field strength on the front surface side increases and the electric field strength on the back surface side decreases.

  As shown in FIG. 4, in the state where the end metal positions of the front surface metal substrate 2 and the back surface metal substrate 3 are matched, if the dielectric constant of the insulating substrate 1 is larger than that of the gel insulator 5, the front surface metal substrate The electric field strengths at the intersection (triple point) of 2, insulating substrate 1 and gel insulator 5 and at the intersection (triple point) of backside metal substrate 3, insulating substrate 1 and gel insulator 5 are shown in FIG. With respect to the reference position of a), when the insulating substrate 1 is lengthened as shown in FIG. 4B and the distance to the end portion is increased, the distance is lowered, and as shown in FIG. 4C, the insulating substrate 1 is shortened. As the distance to the edge becomes shorter, it rises. In the configuration in which the insulating substrate 1 is made of ceramics such as alumina or aluminum nitride, and the silicone gel is used as the gel-like insulator 5, the relative dielectric constant of alumina is about 8.3. The relative permittivity of aluminum is about 8.8, whereas the relative permittivity of silicone gel is about 2.9, which corresponds to the above case.

  On the other hand, in FIG. 4, when the dielectric constant of the insulating substrate 1 is smaller than that of the gel-like insulator 5, contrary to the above case, the intersection of the surface metal substrate 2, the insulating substrate 1 and the gel-like insulator 5 ( 3), each electric field strength at the intersection (triple point) of the back metal substrate 3, the insulating substrate 1 and the gel insulator 5 is as shown in FIG. 4B with respect to the reference position of FIG. In this way, if the insulating substrate 1 is lengthened and the distance to the end portion becomes long, it rises, and if the insulating substrate 1 is shortened and the distance to the end portion becomes short as shown in FIG.

Thus, by adjusting the positions of the front surface metal substrate 2 and the back surface metal substrate 3, the maximum electric field strength of the partial discharge generating substrate portion 103 can be arbitrarily set.
There are roughly two methods for generating and detecting a partial discharge in the “partial discharge generating substrate”. The first method is a method in which a partial discharge that is unlikely to cause dielectric breakdown is generated on the back metal substrate side in the partial discharge generation substrate unit 103, and the generated partial discharge is detected by a sensor. The second method is a method in which a partial discharge that tends to cause dielectric breakdown is generated on the surface metal substrate side in the partial discharge generation substrate unit 103, and a short circuit in the partial discharge generation substrate unit is detected by a sensor. A specific structure of the partial discharge generating substrate portion corresponding to the above two methods will be described.

(Configuration of the present invention)
According to the present invention, the main functional circuit surface metal substrate portion for forming the main functional circuit pattern on the semiconductor element is bonded to the surface of the insulating substrate, and the back surface metal substrate to be grounded is the back surface of the insulating substrate. A high-voltage module in which the insulating substrate, the front surface metal substrate portion for the main functional circuit, the back surface metal substrate, and the semiconductor element are sealed with a gel-like insulator; A partial discharge generation region, the main functional circuit surface metal substrate portion is disposed on a surface of the main functional circuit region of the insulating substrate, and the main discharge circuit is provided on the surface of the partial discharge generation region of the insulating substrate. A surface metal substrate for partial discharge generation is disposed separately from the surface metal substrate portion for functional circuit, the surface metal substrate portion for main function circuit, and the region for main function circuit of the insulating substrate, A portion of the back surface metal substrate that is disposed on the back surface of the main functional circuit region of the insulating substrate constitutes a main function substrate portion, and the partial discharge generating surface metal substrate and a portion of the insulating substrate A partial discharge generating substrate portion is constituted by a discharge generating region and a portion of the back metal substrate disposed on the back surface of the partial discharge generating region of the insulating substrate, and the partial discharge generating surface metal substrate. Is the same potential as the high potential surface metal substrate which is the highest potential among the surface metal substrate parts for the main functional circuit, and the high potential surface metal substrate, the partial metal substrate for generating a partial discharge, and the back metal substrate The maximum electric field strength in the partial discharge generating substrate portion is larger than the maximum electric field strength in the main functional substrate portion. Set Kunar so, a structure in which a means for detecting the partial discharge or short-circuit occurring in the partial discharge generating substrate portion (first aspect of the present invention).

  According to the first aspect of the present invention, the partial discharge or short circuit generated in the partial discharge generating substrate portion having the maximum electric field strength larger than that of the main functional substrate portion is detected. Or, based on the detection result of the short-circuit, measures such as replacement of the high-voltage module with a new one can be taken before dielectric breakdown occurs in the main functional circuit of the high-voltage module. It becomes possible to prevent dielectric breakdown in the main functional circuit of the high-voltage module in the state.

  Next, in the high voltage module according to claim 1, the position of the end portion of the surface metal substrate for generating partial discharge is an end portion of the insulating substrate with respect to the end portion of the back surface metal substrate facing the insulating substrate. It is set as the position which protruded by the side, and was provided with the partial discharge detection means which detects the partial discharge which generate | occur | produces in the said back surface metal substrate side (Invention of Claim 2).

  Next, in the high voltage module according to claim 1, the insulating substrate is made of a material having a relative dielectric constant larger than that of the gel-like insulator, and the position of the end portion of the partial discharge generating surface metal substrate is The distance between the end portion of the surface metal substrate for generating partial discharge and the end portion of the insulating substrate is the same as the position of the end portion of the backside metal substrate facing each other across the insulating substrate. The shortest distance between the surface metal substrate for partial discharge generation and the back metal substrate that is generated along with the partial discharge generated on the side of the surface metal substrate for partial discharge generation with the shortest distance among all the metal substrates to be bonded. A short-circuit detecting means for detecting the above is provided (invention of claim 3).

  Next, in the high-voltage module according to claim 2, a current-type partial discharge sensor provided with a current detection element for detecting a current generated in association with the partial discharge is provided as the partial discharge detection means ( Invention of Claim 4).

  Next, in the high voltage module according to claim 2, an acoustic partial discharge sensor provided with a sound detection element for detecting a sound generated with the partial discharge is provided as the partial discharge detection means. Item 5).

  Next, in the high voltage module according to claim 2, an optical partial discharge sensor including a light detection element that detects light generated by the partial discharge is provided as the partial discharge detection unit ( Invention of Claim 6).

  Next, in the high-voltage module according to claim 3, a short-circuit sensor including a resistor through which a current caused by the short-circuit flows and a potential difference measurement circuit unit that measures a potential difference between both ends of the resistor are used as the short-circuit detection unit. It is set as the structure provided (invention of Claim 7).

Next, in the high voltage module according to claim 7, a current interrupting portion is interposed in series with the resistor (invention of claim 8).
Next, in the high voltage module according to any one of claims 1 to 8, the insulating substrate is made of ceramics (invention 9).

  Next, in the high voltage module according to any one of claims 1 to 9, the gel-like insulator is made of silicone gel (invention of claim 10).

  According to the present invention, it is possible to prevent dielectric breakdown in the main functional circuit of the high-voltage module.

It is a schematic cross section which shows the partial discharge generation | occurrence | production location in the gel-like insulator in a high voltage | pressure module. It is a schematic cross section which illustrates the basic composition of the high voltage module by the present invention. It is a schematic cross section which shows the example of the electric field strength change at the time of changing the edge part position of a front and back metal substrate. It is a schematic cross section which shows the example from which the electric field strength change at the time of changing the edge part position of a front and back metal substrate is different. It is a figure which shows the structure of the high voltage | pressure module by Example 1 of this invention. It is a figure which shows the structure of the high voltage | pressure module by Example 2 of this invention. It is a figure which shows the structure of the high voltage | pressure module by Example 3 of this invention. It is a figure which shows the structure of the high voltage | pressure module by Example 4 of this invention. It is a figure which shows the structure of the high voltage | pressure module by Example 5 of this invention. It is explanatory drawing which shows typically the effect of this invention with respect to the partial discharge accompanying an instantaneous high voltage. It is explanatory drawing which shows typically the effect of this invention with respect to the partial discharge accompanying a time-dependent change of a gel physical property. It is a schematic cross section which shows the structural example of the conventional high voltage | pressure module.

  Hereinafter, embodiments of the present invention will be described based on examples shown in FIGS. About the same component, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted. In addition, this invention is not limited to the following embodiment, In the range which does not change the summary, it can implement suitably.

  FIG. 5 is a diagram showing a configuration of the high voltage module 111 according to the first embodiment of the present invention. 5A schematically shows a cross-sectional structure of the high-voltage module 111, and FIG. 5B schematically shows an electrical connection configuration in the high-voltage module 111. As shown in FIG. FIG. 5C shows a configuration example of the current type partial discharge sensor 31 in the high voltage module 111.

  The internal insulation structure of the high voltage module 111 according to the first embodiment is basically the same as that of the conventional high voltage module 101A described with reference to FIG. This is different from the main functional circuit surface metal substrate portion made of the substrate 2a in that a separate partial discharge generating surface metal substrate 21 is further provided. That is, as shown in FIG. 5A, the internal insulation structure of the high-voltage module 111 is as follows: the ground plate 6, the back metal substrate 3, the insulation substrate 1, the “surface metal substrate for element mounting 2a and the partial discharge generation” from the bottom. The surface metal substrate 21 "is laminated in this order. Further, the semiconductor element 4 is mounted on the element mounting surface metal substrate 2a, and a current type partial discharge sensor 31 is attached to the partial discharge generating surface metal substrate 21. As described above with reference to FIG. 2, on the surface of the insulating substrate 1, another surface metal substrate may be provided together with the element mounting surface metal substrate 2 a as the main functional circuit surface metal substrate portion. However, in the following, a configuration example in which the main functional circuit surface metal substrate portion is composed of the element mounting surface metal substrate 2a will be described.

  The substrate part structure comprising the insulating substrate 1, the element mounting surface metal substrate 2a, the back surface metal substrate 3 and the partial discharge generating surface metal substrate 21 in the high voltage module 111 is a DBC substrate having a direct bonding structure for improving thermal conductivity. The element mounting surface metal substrate 2 a on which the semiconductor element 4 is mounted is electrically connected to the module external terminal 8 by a bonding wire 10. Further, the back metal substrate 3 is joined to a ground plate 6 that extends at least to the outer peripheral side of the back metal substrate 3 and is conductively connected to the ground plate 6. The current type partial discharge sensor 31 attached to the partial discharge generating surface metal substrate 21 is electrically connected to the module external terminal 9 by the bonding wire 14.

  The inside of the high voltage module 111 is filled with the gel insulator 5 to insulate the periphery of the high voltage component. The insulating substrate 1 is made of a ceramic such as alumina or aluminum nitride. In addition, silicone gel is particularly preferably used as the gel insulator 5, but is not limited thereto. Moreover, although each metal board | substrate joined to both surfaces of the insulated substrate 1 can be formed from a copper material, for example, it is not limited to this. The ground plate can also be formed from, for example, a copper material, but is not limited to this. In addition, about the material of the insulated substrate 1, the gel-like insulator 5, each metal substrate, and the earth board 6, it is the same also in the following Examples 2-5.

  Further, the thickness of the insulating substrate 1 can be set to, for example, about 0.5 mm, but is not limited thereto. Furthermore, the thickness of each metal substrate can be, for example, about 0.1 mm, but is not limited thereto. The thickness of the insulating substrate 1 and each metal substrate is the same in the following Examples 2 to 5.

  In the high-voltage module 111, as shown in FIG. 5A, a main functional circuit area and a partial discharge generation area are provided on the insulating substrate 1, and the element mounting surface is provided on the surface of the main functional circuit area of the insulating substrate 1. A metal substrate 2a is provided, and a partial discharge generating surface metal substrate 21 is provided on the surface of the partial discharge generating region of the insulating substrate 1 separately from the element mounting surface metal substrate 2a. The element mounting surface metal substrate 2 a on which the semiconductor element 4 is mounted, the main functional circuit region of the insulating substrate 1, and the back surface of the main metal circuit region of the insulating substrate 1 of the back metal substrate 3. The main functional board portion 112 is formed from the existing portion. Further, a partial discharge generating surface metal substrate 21 to which the current type partial discharge sensor 31 is attached, a partial discharge generating region of the insulating substrate 1, and a rear surface of the partial discharge generating region of the insulating substrate 1 among the back metal substrate 3. A partial discharge generating substrate portion 113 is formed from the disposed portion. The main functional substrate 112 and the partial discharge generating substrate 113 are also sealed with the gel insulator 5.

  In the high voltage module 111, as shown in FIG. 5A, the surface metal substrate 21 for partial discharge generation is provided on the surface of the insulating substrate 1 separately from the surface metal substrate 2a for element mounting, and the surface for partial discharge generation is provided. The potential of the metal substrate 21 is the same as that of the element mounting surface metal substrate 2 a connected to the high voltage power source 201. In FIG. 5B, the semiconductor element 4 mounted on the element mounting surface metal substrate 2a is an IGBT, and the collector side of the semiconductor element 4 is conductively connected to the element mounting surface metal substrate 2a. An example is shown. In FIG. 5B, the ground plate 6 is not shown.

  In the partial discharge generating substrate portion 113, the position of the end portion of the partial discharge generating front surface metal substrate 21 is the end portion side of the insulating substrate 1 with respect to the end portion of the back surface metal substrate 3 facing the insulating substrate 1 therebetween. It is made to protrude by. By using this structure, the back metal substrate 3, the insulating substrate 1, the gel insulator 5, and the intersection point (triple point) between the surface metal substrate 21 for partial discharge generation, the insulating substrate 1, and the gel insulator 5 The electric field intensity at the crossing point (triple point) increases, and partial discharge occurs on the back metal substrate 3 side in the partial discharge substrate portion 113.

  And each distance L1-L4 of the edge part of each metal substrate joined to the insulated substrate 1 in Example 1 and the edge part of the insulated substrate 1 is set so that the relationship between each distance may become as follows. As a result, the electric field strength on the back metal substrate 3 side of the partial discharge generating substrate portion 113 among the electric field strengths of the respective portions in the high voltage module 111 is maximized, and the partial discharge 301 starts to be generated from this portion. (See FIG. 5B).

(A) L1 = L2.
(B) L3 <L1.
(C) L4> L3.

  Here, in the main functional substrate 112, the distance between the end of the element mounting surface metal substrate 2a and the end of the insulating substrate 1 is L1, and the end of the back metal substrate 3 and the end of the insulating substrate 1 are Is the distance L2. In the partial discharge generating substrate portion 113, the distance between the end portion of the partial discharge generating surface metal substrate 21 and the end portion of the insulating substrate 1 is L3, and the end portion of the back surface metal substrate 3 and the end of the insulating substrate 1 are set. The distance to the part is L4. Such meanings of L1 to L4 are the same in the following Examples 2 to 5.

  The distances L3 and L4 in the first embodiment can be set to L3 = 5 mm and L4 = 10 mm, for example, but are not limited to such distance settings. Further, as described above, in Example 1, the back surface metal substrate 3 is joined to the ground plate 6 that extends at least to the outer peripheral side of the back surface metal substrate 3 and is conductively connected to the ground plate 6. The electric field at the intersection (triple point) of the back metal substrate 3, the insulating substrate 1, and the gel insulator 5 is moderated to some extent due to the presence of the ground plate 6, depending on the thickness of the back metal substrate 3. For this reason, in actuality, the electric field relaxation effect by the ground plate 6 as described above is also taken into consideration, and the intersection of the back surface metal substrate 3, the insulating substrate 1, and the gel-like insulator 5 in the partial discharge generating substrate portion 113 ( The distance L3 and the distance L4 are set so that the electric field strength at the triple point is higher than the electric field strength at the intersection (triple point) of the surface metal substrate 21 for partial discharge generation, the insulating substrate 1 and the gel insulator 5. To do.

In the high voltage module 111, the current-type partial discharge sensor 31 detects that the partial discharge 301 has occurred on the back metal substrate 3 side of the partial discharge generation substrate portion 113.
In the high voltage module 111, as shown in FIG. 5A, a current type partial discharge sensor 31 is attached to the surface metal substrate 21 for partial discharge generation on the surface of the insulating substrate 1, and the partial discharge is performed by the current type partial discharge sensor 31. 301 is detected. The electric current type partial discharge sensor 31 is electrically connected between the external terminal 9 connected to the high voltage power source 201 and the partial discharge generating surface metal substrate 21 as shown in FIG. Note that the bonding wire 14 from the external terminal 9 is joined to the current type partial discharge sensor 31 as shown in FIG.

  The current-type partial discharge sensor 31 performs partial discharge detection by detecting the partial discharge current 311. For example, as shown in FIG. 5C, the high-frequency current transformer (10) is capable of detecting 10 kHz to 1 MHz. CT) 32 and a signal processing circuit unit 33 that outputs a partial discharge detection signal 321 based on the current detection output of the high-frequency current transformer 32 can be provided. In the present invention, instead of the current-type partial discharge sensor as described above, a partial discharge sensor of a system that detects an amount of partial discharge charge by attaching an integrator made of, for example, an operational amplifier can also be applied. The signal processing circuit unit 33 includes a threshold discrimination circuit for preventing malfunction due to noise.

  In FIG. 5A, the high-voltage module 111 includes the external terminal 8 for the main functional board 112 and the external terminal 9 for the partial discharge generation board 113 as high-voltage power connection terminals. Although the structure connected to both the external terminals 8 and 9 is shown, the high-voltage module 111 includes only the external terminal 8 as a high-voltage power supply connection terminal, and the internal terminal of the high-voltage module 111 is connected to the external terminal 8 to which the high-voltage power supply 201 is connected. The main functional board part 112 and the partial discharge generating board part 113 may be branched and connected by the wiring. This also applies to Examples 2 to 5 below.

  In the high voltage module 111 according to the first embodiment, the surface metal substrate 21 for partial discharge generation is separated from the element mounting surface metal substrate 2 a on which the semiconductor element 4 is mounted on the surface side of the insulating substrate 1. The partial discharge sensor 31 can detect the partial discharge current without being affected by the energization current and switching current of the semiconductor element 4.

  FIG. 6 is a diagram showing a configuration of the high voltage module 121 according to the second embodiment of the present invention. 6A schematically shows a cross-sectional structure of the high-voltage module 121, and FIG. 6B schematically shows an electrical connection configuration in the high-voltage module 121. FIG. 6C shows a configuration example of the acoustic partial discharge sensor 41 in the high voltage module 121.

  In the high-voltage module 121, as shown in FIG. 6A, a main functional circuit region and a partial discharge generation region are provided on the insulating substrate 1, and the element mounting surface is provided on the surface of the main functional circuit region of the insulating substrate 1. A metal substrate 2a is provided, and a partial discharge generating surface metal substrate 21 is provided on the surface of the partial discharge generating region of the insulating substrate 1 separately from the element mounting surface metal substrate 2a. The element mounting surface metal substrate 2 a on which the semiconductor element 4 is mounted, the main functional circuit region of the insulating substrate 1, and the back surface of the main metal circuit region of the insulating substrate 1 of the back metal substrate 3. The main functional board portion 122 is formed from the portion. Further, a partial discharge generating surface metal substrate 21, a partial discharge generating region of the insulating substrate 1, and a portion of the back metal substrate 3 disposed on the back surface of the partial discharge generating region of the insulating substrate 1, A discharge generating substrate portion 123 is formed. The main function substrate portion 122 and the partial discharge generating substrate portion 123 are sealed with the gel-like insulator 5. Note that the internal insulation structure of the high-voltage module 121 is formed by laminating the ground plate 6, the back metal substrate 3, the insulating substrate 1, “element mounting surface metal substrate 2 a and partial discharge generating surface metal substrate 21” in this order from the bottom. These are the same as the internal insulation structure of the high voltage module 111 described in FIG.

  The structure of the main functional substrate part 122 and the partial discharge generating substrate part 123 in the high-voltage module 121, that is, how to set the distance between the end of each metal substrate joined to the insulating substrate 1 and the insulating substrate 1 is as follows. This is the same as the main functional board 112 and the partial discharge generating board 113 in the high voltage module 111 according to the first embodiment. That is, the distances L1 to L4 between the end portions of the respective metal substrates and the end portions of the insulating substrate 1 bonded to the insulating substrate 1 in Example 2 are set so that the relationship between the distances is as follows. Thus, the electric field strength on the back metal substrate 3 side of the partial discharge generating substrate portion 123 among the electric field strengths of the respective portions in the high voltage module 121 is maximized, and the partial discharge 301 starts to be generated from this portion. (See FIG. 6B).

(A) L1 = L2.
(B) L3 <L1.
(C) L4> L3.

In the high voltage module 121, the acoustic partial discharge sensor 41 detects that the partial discharge 301 has occurred on the back metal substrate 3 side of the partial discharge generating substrate portion 123.
In the high-voltage module 121, for example, as shown in FIG. 6A, the partial discharge generating substrate portion 123 corresponds to the position immediately above the generation position of the partial discharge 301 on the back surface side on the partial discharge generating surface metal substrate 21. The acoustic partial discharge sensor 41 is attached to a position on the surface metal substrate 21 for generating partial discharge, which is an upper layer of the intersection (triple point) of the back surface metal substrate 3, the gel insulator 5 and the insulating substrate 1. The partial discharge 301 is detected by the acoustic partial discharge sensor 41.

  The acoustic partial discharge sensor 41 performs partial discharge detection by detecting a partial discharge sound 312, that is, a sound wave accompanying the generation of the partial discharge 301. For example, as shown in FIG. A sound detection element 42 such as a microphone and a signal processing circuit unit 43 that outputs a partial discharge detection signal 322 based on the sound detection output of the sound detection element 42 can be provided. As the sound detection element 42, for example, a contact-type high-sensitivity piezoelectric microphone that can detect up to about 400 kHz is preferably used. The signal processing circuit unit 43 includes a threshold discrimination circuit for preventing malfunction due to noise.

Note that the mounting position of the acoustic partial discharge sensor 41 is not limited to the position shown in FIG. 6A described above, and may be a position where the partial discharge sound 312 can be detected with sufficient sensitivity.
In the high voltage module 121 according to the second embodiment, since the partial discharge occurrence position can be specified, only one sound detection element is required, and a microphone having a narrow directional characteristic can be applied as the sound detection element.

  FIG. 7 is a diagram showing the configuration of the high voltage module 131 according to the third embodiment of the present invention. FIG. 7A schematically shows a cross-sectional structure of the high-voltage module 131, and FIG. 7B schematically shows an electrical connection configuration in the high-voltage module 131. FIG. 7C shows a configuration example of the optical partial discharge sensor 51 in the high voltage module 131.

  In the high-voltage module 131, as shown in FIG. 7A, a main functional circuit area and a partial discharge generation area are provided on the insulating substrate 1, and the element mounting surface is provided on the surface of the main functional circuit area of the insulating substrate 1. A metal substrate 2a is provided, and a partial discharge generating surface metal substrate 21 is provided on the surface of the partial discharge generating region of the insulating substrate 1 separately from the element mounting surface metal substrate 2a. The element mounting surface metal substrate 2 a on which the semiconductor element 4 is mounted, the main functional circuit region of the insulating substrate 1, and the back surface of the main metal circuit region of the insulating substrate 1 of the back metal substrate 3. The main functional board portion 132 is formed from the portion. Further, a partial discharge generating surface metal substrate 21, a partial discharge generating region of the insulating substrate 1, and a portion of the back metal substrate 3 disposed on the back surface of the partial discharge generating region of the insulating substrate 1, A discharge generating substrate part 133 is formed. The main functional substrate portion 132 and the partial discharge generating substrate portion 133 are sealed with the gel-like insulator 5. The internal insulation structure of the high-voltage module 131 is formed by laminating the ground plate 6, the back surface metal substrate 3, the insulating substrate 1, “the element mounting surface metal substrate 2 a and the partial discharge generating surface metal substrate 21” in this order from the bottom. These are the same as the internal insulation structure of the high voltage module 111 described in FIG.

  The structure of the main functional board part 132 and the partial discharge generating board part 133 in the high-voltage module 131, that is, how to set the respective distances between the end of each metal substrate bonded to the insulating substrate 1 and the insulating substrate 1 is as follows. This is the same as the main functional board 112 and the partial discharge generating board 113 in the high voltage module 111 according to the first embodiment. That is, the distances L1 to L4 between the end portions of the metal substrates and the end portions of the insulating substrate 1 bonded to the insulating substrate 1 in Example 3 are set so that the relationship between the distances is as follows. As a result, the electric field intensity on the back metal substrate 3 side of the partial discharge generating substrate part 133 among the electric field intensity of each part in the high voltage module 131 is maximized, and the partial discharge 301 starts to be generated from this part. (See FIG. 7B).

(A) L1 = L2.
(B) L3 <L1.
(C) L4> L3.

In the high voltage module 131, the optical partial discharge sensor 51 detects that the partial discharge 301 has occurred on the rear metal substrate 3 side of the partial discharge generating substrate part 133.
In the high voltage module 131, for example, as shown in FIG. 7A, the partial discharge generating substrate portion 133 corresponds to the position immediately above the generation position of the partial discharge 301 on the back surface side on the partial discharge generating surface metal substrate 21. An optical partial discharge sensor 51 is attached at a position on the surface metal substrate 21 for generating partial discharge, which is an upper layer of the intersection (triple point) of the back surface metal substrate 3, the gel insulator 5 and the insulating substrate 1. The partial discharge 301 is detected by the optical partial discharge sensor 51.

  The optical partial discharge sensor 51 performs partial discharge detection by detecting partial discharge light 313, that is, light emission accompanying generation of the partial discharge 301. For example, as shown in FIG. The element 52 and the signal processing circuit unit 53 that outputs the partial discharge detection signal 323 based on the light detection output of the light detection element 52 can be used. Further, as the light detection element 52, for example, a method of detecting light emission due to the occurrence of partial discharge with a light receiving element using a photocoupler can be applied. If the photodetecting element 52 is a photocoupler, both the receiving part and the transmitting part are insulated, and the degree of freedom of installation is high, and it is mounted on the peripheral part of the partial discharge generating metal substrate 21 on the surface of the insulating substrate 1. Preferred above. The signal processing circuit unit 53 is provided with a threshold discrimination circuit for preventing malfunction due to noise.

  The attachment position of the optical partial discharge sensor 51 is not limited to the position shown in FIG. 7A described above, and may be a position where the partial discharge light 313 can be detected with sufficient sensitivity. Further, the light detecting element 52 has an intersection (triple point) between the back surface metal substrate 3, the gel-like insulator 5, and the insulating substrate 1 in which the focus of the light detecting element 52 is below the surface metal substrate 21 for partial discharge generation. It is preferable to install as described above.

  In the high voltage module 131 according to the third embodiment, since the optical partial discharge sensor 51 is used, it is necessary to apply a gel having sufficiently high translucency to the gel insulator 5. Gels are particularly suitable.

  FIG. 8 is a diagram showing a configuration of a high voltage module 141 according to the fourth embodiment of the present invention. FIG. 8A schematically shows a cross-sectional structure of the high-voltage module 141, and FIG. 8B schematically shows an electrical connection configuration in the high-voltage module 141. FIG. 8C shows a configuration example of the short circuit sensor 61 provided in the high voltage module 141.

  In the high-voltage module 141, as shown in FIG. 8A, a main functional circuit area and a partial discharge generation area are provided on the insulating substrate 1, and the element mounting surface is provided on the surface of the main functional circuit area of the insulating substrate 1. A metal substrate 2a is provided, and a partial discharge generating surface metal substrate 21A is provided on the surface of the partial discharge generating region of the insulating substrate 1 separately from the element mounting surface metal substrate 2a. The element mounting surface metal substrate 2 a on which the semiconductor element 4 is mounted, the main functional circuit region of the insulating substrate 1, and the back surface of the main metal circuit region of the insulating substrate 1 of the back metal substrate 3. The main functional board part 142 is formed from the part. Further, the partial discharge generating surface metal substrate 21A to which the short circuit sensor 61 is connected, the partial discharge generating region of the insulating substrate 1, and the back surface of the partial discharge generating region of the insulating substrate 1 among the back metal substrate 3 are disposed. A partial discharge generating substrate portion 143 is formed from the portion that is present. The main functional substrate portion 142 and the partial discharge generating substrate portion 143 are sealed with the gel-like insulator 5. The materials of the insulating substrate 1 and the gel-like insulator 5 are selected so that the relative dielectric constant of the insulating substrate 1 is larger than that of the gel-like insulator 5. In addition, the internal insulation structure of the high voltage module 141 in which the ground plate 6, the back metal substrate 3, the insulating substrate 1, and the "element mounting surface metal substrate 2a and partial discharge generating surface metal substrate 21A" are laminated in this order from the bottom. Is the same as the internal insulation structure of the high voltage module 111 described with reference to FIG. 5A except for the setting of distances L1 to L4 described later.

  In the high voltage module 141, as shown in FIG. 8A, the surface metal substrate 21A for partial discharge generation is provided on the surface of the insulating substrate 1 separately from the element mounting surface metal substrate 2a, and the surface for partial discharge generation is provided. The potential of the metal substrate 21A is the same as that of the element mounting surface metal substrate 2a connected to the high voltage power source 201. In the partial discharge generating substrate portion 143, the end positions of the partial discharge generating front surface metal substrate 21A bonded to the surface of the insulating substrate 1 and the back surface metal substrate 3 bonded to the back surface of the insulating substrate 1 are matched. At the same time, the distances between the end portions of the front discharge metal substrate 21A and the back metal substrate 3 and the end portions of the insulating substrate 1 are shortened. By using this structure, the electric field strength at the intersection (triple point) of the surface metal substrate 21A for partial discharge generation, the insulating substrate 1 and the gel insulator 5 is increased, and the partial discharge generation portion 143 in the partial discharge substrate portion 143 is used. A partial discharge 301 is generated on the surface metal substrate 21A side. Further, in this structure, since the creeping distance between the partial discharge generating front surface metal substrate 21A and the back surface metal substrate 3 in the partial discharge generating substrate portion 143 is short, the partial discharge 301 tends to progress to the dielectric breakdown (short circuit) 302. It has become.

  And each distance L1-L4 of the edge part of each metal substrate joined to the insulated substrate 1 in Example 4 and the edge part of the insulated substrate 1 is set so that the relationship between each distance may become as follows. Accordingly, the electric field strength on the partial discharge generating surface metal substrate 21A side of the partial discharge generating substrate portion 143 is maximized among the electric field strengths of the respective portions in the high voltage module 141, and the partial discharge 301 is generated from this portion. Generation is started (see FIG. 8B).

(A) L1 = L2.
(B) L3 = L4.
(C) L3 <L1.

  In Example 4, the end position of the partial discharge generating front surface metal substrate 21A bonded to the surface of the insulating substrate 1 and the back surface metal substrate 3 bonded to the back surface of the insulating substrate 1 are matched. In the fourth embodiment, as in the first embodiment, the back metal substrate 3 is joined to the ground plate 6 that extends at least to the outer peripheral side of the back metal substrate 3 and is conductively connected to the ground plate 6. For this reason, the electric field at the intersection (triple point) of the back surface metal substrate 3, the insulating substrate 1, and the gel insulator 5 in the partial discharge generating substrate portion 143 is caused by the thickness of the back surface metal substrate 3 due to the presence of the ground plate 6. Although it depends, it is eased to some extent. Thus, in Example 4, the electric field strength at the intersection (triple point) of the partial discharge generating surface metal substrate 21, the insulating substrate 1, and the gel insulator 5 in the partial discharge generating substrate portion 143 is different from that of the back surface metal substrate 3. It is higher than the electric field strength at the intersection (triple point) between the insulating substrate 1 and the gel-like insulator 5.

  In the high voltage module 141, the partial discharge 301 is generated on the partial discharge generating surface metal substrate 21 A side of the partial discharge generating substrate portion 143, and the dielectric breakdown occurs between the partial discharge generating surface metal substrate 21 A and the back surface metal substrate 3. (Short circuit) 302 is detected by the short circuit sensor 61.

  In the high voltage module 141, as shown in FIG. 8A, a short circuit sensor 61 is attached to a position adjacent to the partial discharge generating surface metal substrate 21 </ b> A on the surface of the insulating substrate 1. A dielectric breakdown (short circuit) 302 is detected. As shown in FIG. 8B, the short-circuit sensor 61 is electrically connected between the external terminal 9 connected to the high-voltage power supply 201 and the partial discharge generating surface metal substrate 21A. Note that the bonding wire 14 from the external terminal 9 is bonded to the short circuit sensor 61 as shown in FIG.

  The short-circuit sensor 61 basically includes a resistor and a potential difference measuring circuit. For example, as shown in FIG. 8C, the short-circuit sensor 61 has a resistor 62 having a resistance value R1 and a resistance value R2 lower than R1. A series connection circuit with the resistor 63, a differential potential meter type potential difference measurement circuit unit 64 that measures a potential difference between both ends of the resistor 63, and a signal that outputs a short circuit detection signal 324 based on the potential difference detection output of the potential difference measurement circuit unit 64 A configuration including a processing circuit unit 65 can be adopted. The signal processing circuit unit 65 is provided with a threshold discrimination circuit for preventing malfunction due to noise.

  Before the dielectric breakdown (short circuit) 302 caused by the partial discharge 301 occurs, the short circuit current 314 does not flow, so that the potential difference ΔV across the resistor 63 is zero. If a dielectric breakdown (short circuit) 302 occurs between the metal substrate 3 and the potential difference ΔV due to the short circuit current 314 flowing through the resistor 63, the potential difference measurement circuit unit 64 detects the potential difference ΔV. A short circuit detection signal 324 is output. Here, the potential difference ΔV when the dielectric breakdown (short circuit) 302 occurs can be expressed as ΔV = Is × R2 = V × R2 / (R1 + R2). Here, V is an applied voltage from the high-voltage power supply 201, and Is = V / (R1 + R2) is a current value of the short-circuit current 314.

  In the high voltage module 141 according to the fourth embodiment, the partial discharge generating surface metal substrate 21A is separated on the surface of the insulating substrate 1 from the element mounting surface metal substrate 2a on which the semiconductor element 4 is mounted. Even if dielectric breakdown (short circuit) 302 occurs on the partial discharge generation substrate portion 143 side including the generation surface metal substrate 21A, the semiconductor element 4 is not damaged.

  FIG. 9 is a diagram showing a configuration of a high voltage module 151 according to the fifth embodiment of the present invention. 9A schematically shows a cross-sectional structure of the high-voltage module 151, and FIG. 9B schematically shows an electrical connection configuration in the high-voltage module 151. FIG. 9C shows a configuration example of the short circuit sensor 71 provided in the high voltage module 151.

  In the high-voltage module 151, as shown in FIG. 9A, a main functional circuit region and a partial discharge generation region are provided on the insulating substrate 1, and an element mounting surface is provided on the surface of the main functional circuit region of the insulating substrate 1. A metal substrate 2a is provided, and a partial discharge generating surface metal substrate 21A is provided on the surface of the partial discharge generating region of the insulating substrate 1 separately from the element mounting surface metal substrate 2a. The element mounting surface metal substrate 2 a on which the semiconductor element 4 is mounted, the main functional circuit region of the insulating substrate 1, and the back surface of the main metal circuit region of the insulating substrate 1 of the back metal substrate 3. The main functional board portion 152 is formed from the portion. The partial discharge generating surface metal substrate 21A to which the short-circuit sensor 71 is connected, the partial discharge generating region of the insulating substrate 1, and the back surface of the partial discharge generating region of the insulating substrate 1 among the back metal substrate 3. A partial discharge generating substrate portion 153 is formed from the portion that is present. The main functional substrate portion 152 and the partial discharge generating substrate portion 153 are sealed with the gel-like insulator 5. The materials of the insulating substrate 1 and the gel-like insulator 5 are selected so that the relative dielectric constant of the insulating substrate 1 is larger than that of the gel-like insulator 5. In addition, the internal insulation structure of the high voltage module 151 in which the ground plate 6, the back surface metal substrate 3, the insulating substrate 1, the “element mounting surface metal substrate 2 a and the partial discharge generating surface metal substrate 21 A” are stacked in this order from the bottom. Is the same as the internal insulation structure of the high voltage module 111 described with reference to FIG. 5A except for the setting of distances L1 to L4 described later.

  The structure of the main functional substrate portion 152 and the partial discharge generating substrate portion 153 in the high-voltage module 151, that is, how to set the respective distances between the end portions of the respective metal substrates joined to the insulating substrate 1 and the insulating substrate 1 are as follows. This is the same as the main functional board 142 and the partial discharge generating board 143 in the high voltage module 141 according to the fourth embodiment. That is, the distances L1 to L4 between the end portions of the respective metal substrates bonded to the insulating substrate 1 and the end portions of the insulating substrate 1 in Example 5 are set so that the relationship between the distances is as follows. Accordingly, the electric field strength on the partial discharge generating surface metal substrate 21A side of the partial discharge generating substrate portion 153 among the electric field strengths of the respective portions in the high voltage module 151 is maximized, and the partial discharge 301 is generated from this portion. The generation starts (see FIG. 9B).

(A) L1 = L2.
(B) L3 = L4.
(C) L3 <L1.

  In the high voltage module 151, the partial discharge 301 is generated on the partial discharge generating surface metal substrate 21 A side of the partial discharge generating substrate portion 153, and the partial discharge generating surface metal substrate 21 A and the back metal substrate are generated along with the partial discharge 301. 3, the short circuit sensor 71 detects that a dielectric breakdown (short circuit) 302 has been reached.

  Further, the arrangement configuration (see FIG. 9A) and the connection configuration (see FIG. 9B) of the short-circuit sensor 71 in the high-voltage module 151 are the same as those of the short-circuit sensor 61 in the high-voltage module 141 according to the fourth embodiment. .

  The short-circuit sensor 71 is basically composed of a resistor and a potential difference measuring circuit, similarly to the short-circuit sensor 61 in the above-described fourth embodiment, but is different in that it further includes a current interrupting unit. For example, as shown in FIG. 9C, the short circuit sensor 71 measures a potential difference between both ends of the resistor 73 and a series connection circuit of a resistor 72 having a resistance value R1 and a resistor 73 having a resistance value R2 lower than R1. And a signal processing circuit unit 75 that outputs a short-circuit detection signal 325 based on the potential difference detection output of the potential difference measurement circuit unit 74, and further includes a signal processing circuit unit 75. The current cut-off unit 76 that cuts off the short-circuit current 314 based on the cut-off command signal 77 from can be configured to be connected in series to the series connection circuit of the resistor 72 and the resistor 73. The signal processing circuit unit 75 includes a threshold discrimination circuit for preventing malfunction due to noise.

  Before the dielectric breakdown (short circuit) 302 caused by the partial discharge 301 occurs, the short circuit current 314 does not flow, so the potential difference ΔV between both ends of the resistor 73 is zero. When a dielectric breakdown (short circuit) 302 occurs between the metal substrate 3 and the potential difference ΔV due to the short circuit current 314 flowing through the resistor 73, the potential difference measurement circuit unit 74 detects the potential difference ΔV. A short circuit detection signal 325 is output.

  The short-circuit sensor 71 further includes a current interrupting unit 76 that interrupts the short-circuit current 314 based on the interrupt command signal 77 from the signal processing circuit unit 75, so that the short-circuit current 314 flows after the dielectric breakdown (short-circuit) 302 occurs. It can be prevented from continuing. The interruption command signal 77 from the signal processing circuit unit 75 to the current interruption unit 76 may be issued when the dielectric breakdown (short circuit) 302 is detected, or the dielectric breakdown (short circuit) 302 is detected. You may make it issue at another timing after the said time.

In the high voltage module 151 according to the fifth embodiment, as in the high voltage module 141 according to the fourth embodiment, the partial discharge generating surface metal substrate 21A is provided on the surface of the insulating substrate 1 on which the semiconductor element 4 is mounted. Since it is separated from the metal substrate 2a, the semiconductor element 4 is not damaged even if dielectric breakdown (short circuit) 302 occurs on the partial discharge generation substrate portion 153 side provided with the partial discharge generation surface metal substrate 21A. .
[Specific Examples of Effects of the Present Invention]
As described above, the high voltage module according to the present invention detects a partial discharge generated in the gel-like insulator in the high voltage module, and generates a partial discharge as a mechanism for preventing dielectric breakdown in the main functional circuit of the high voltage module. Although the board | substrate part is provided, the specific example of the effect by this is demonstrated.
(Specific example 1)
FIG. 10 is an explanatory view schematically showing the action and effect of the present invention with respect to a partial discharge accompanying an instantaneous high voltage. In FIG. 10, the horizontal axis and the vertical axis represent time and electric field strength, respectively. In FIG. 10, solid line A1, broken line B1, and alternate long and short dash line C1 indicate the dielectric breakdown strength of the gel, the maximum electric field strength in the main functional substrate portion, and the maximum electric field strength in the partial discharge generating substrate portion, respectively. The maximum electric field strength in the partial discharge generating substrate portion is designed to be, for example, about 10 to 30% larger than the maximum electric field strength in the main functional substrate portion.

  In FIG. 10, the high voltage module receives an instantaneous high voltage due to instantaneous voltage fluctuations from the specified voltage value (steady level) of the high voltage power supply connected to the high voltage module, and the maximum electric field strength and It is assumed that the maximum electric field strength in the partial discharge generating substrate portion increases instantaneously, and the maximum electric field strength in each substrate portion starts rising from the steady level at time ta and reaches the highest level at time tb. A mode is schematically shown in which, after that, is lowered and then returned to the steady level at time tc. Note that the dielectric breakdown strength of the gel decreases in the long term due to the change in the physical properties of the gel over time, but in the time scale of FIG. 10 for an instantaneous high voltage event, the decrease in the dielectric breakdown strength of the gel is It is assumed that it has not appeared.

  In FIG. 10, when the maximum electric field strength in the partial discharge generating substrate portion increases and exceeds the level of the dielectric breakdown strength of the gel at time t1, the partial discharge may occur on the partial discharge generating substrate portion side. However, when this partial discharge is detected, an alarm is issued at the time of detection based on the partial discharge detection signal output from the high voltage module on the system side such as a power converter equipped with the high voltage module. For example, measures such as preventing the influence on the system by replacing the high-pressure module with a new one can be taken. Further, it is possible to take a measure of taking out the high-pressure module and conducting a detailed inspection to determine whether or not to continue use.

  Note that the instantaneous high voltage level has the following relationship between the voltage levels corresponding to dielectric breakdown and partial discharge events in the main functional board part and the partial discharge generation board part.

VBDm>VPDm>VBDp>VPDp> VPDL
Here, VBDm is a breakdown voltage (BD) generation voltage of the main functional board part, VPDm is a partial discharge (PD) generation voltage of the main function board part, and VBDp is a breakdown (BD) of the partial discharge generation board part. ) Generated voltage, VPDp is a partial discharge (PD) generation voltage of the partial discharge generation substrate portion, and VPD1 is a voltage at which partial discharge (PD) does not occur even in the partial discharge generation substrate portion.

First, if the voltage level V satisfies VPD1> V, there is no problem of insulation, and the partial discharge generating substrate portion does not operate.
Next, if the voltage level V satisfies VPDm> V ≧ VPDp, the partial discharge generating substrate unit operates and warns that there is a possibility of insulation deterioration due to partial discharge in the main functional substrate unit. However, in this case, since the voltage level of VPDm has not actually been reached, no partial discharge has occurred in the main functional board portion. For this reason, it warns about the risk including a margin.

  Next, if the voltage level V satisfies VBDm> V ≧ VPDm, the substrate portion for partial discharge generation operates to warn of the possibility of insulation deterioration due to partial discharge in the main function substrate portion. In this case, partial discharge actually occurs in the main functional board portion. Since the portion where the partial discharge is generated in the gel-like insulator becomes an insulation defect, the partial discharge may continue to be generated even when the normal voltage level is restored.

Furthermore, when the voltage level V satisfies V ≧ VBDm, the main functional board portion breaks down and cannot be dealt with.
The voltage region is designed so that the range of VBDm to VPDm is wide and the range of VPDm to VPDp is narrow.
(Specific example 2)
FIG. 11 is an explanatory diagram schematically showing the action and effect of the present invention on partial discharge accompanying a change in gel physical properties with time. In FIG. 11, the horizontal axis and the vertical axis represent time and electric field strength, respectively. In FIG. 11, solid line A2, broken line B2, and alternate long and short dash line C2 indicate the dielectric breakdown strength of the gel, the maximum electric field strength in the main functional substrate portion, and the maximum electric field strength in the partial discharge generating substrate portion, respectively. The maximum electric field strength in the partial discharge generating substrate portion is designed to be, for example, about 10 to 30% larger than the maximum electric field strength in the main functional substrate portion.

Here, the dielectric breakdown strength of the gel decreases over time due to a change in the physical properties of the gel over time. In FIG. 11, the mode of the decrease is schematically shown as a decrease with a constant time gradient.
The dielectric breakdown strength of the gel decreases with the aging of the physical properties of the gel, the maximum electric field strength in the partial discharge generating substrate portion becomes larger than the dielectric breakdown strength of the gel at time t1, and the maximum in the main functional substrate portion at time t2. The electric field strength is also larger than the dielectric breakdown strength of the gel.

  In the present invention, after the maximum electric field strength in the partial discharge generating substrate portion becomes larger than the dielectric breakdown strength of the gel at time t1, the partial discharge is detected in the partial discharge generating substrate portion. Based on the output partial discharge detection signal, an alarm is issued on the system side such as a power converter equipped with the high-voltage module, for example, to prevent the influence on the system by replacing the high-voltage module with a new one. Measures can be taken. Further, it is possible to take a measure of taking out the high-pressure module and conducting a detailed inspection to determine whether or not to continue use.

  The dielectric breakdown strength of bulk gel-like insulators is determined by the molecular structure of the material, but the insulation performance of gel insulators that are actually used is governed by the state of adhesion, adhesion, and adhesion to high-pressure sites. Is done. That is, it is thought that the characteristic which makes it difficult to form a space | gap between a high voltage | pressure site | part and a gel-like insulator leads to an actual dielectric breakdown characteristic.

  Further, in FIG. 11, it is assumed that the relative dielectric constant does not change even if the dielectric breakdown strength of the gel is lowered as the change in the characteristics of the gel-like insulator, and the maximum electric field strength (dashed line) B2) shows a mode in which the maximum electric field strength (one-dot chain line C2) in the partial discharge generating substrate portion is constant with time, but each maximum electric field is actually affected by the influence of fine defects generated at the interface. Intensity may also change over time.

As described above, in the high voltage module according to the present invention, the partial discharge detection signal from the partial discharge generation substrate provided in the high voltage module is constantly monitored on the system side such as the power converter, so that It can be ensured that partial discharge has not occurred, that is, for example, there has been no insulation degradation due to, for example, instantaneous high voltage, gel property change with time, and the like.
(Specific example 3)
Note that the events targeted by the present invention include that the gel-like insulator is torn or peeled off by impact or heating, and partial discharge is likely to occur. Here, acceleration / deceleration and vibration are assumed as the impact, and temperature rise of the chip (semiconductor element) is assumed as the heating. Since the main functional board part and the partial discharge generating board part are placed in the same environmental conditions sealed with a gel-like insulator in the high voltage module, the main functional board part and the partial discharge generating board are caused by impact or heating. Even if the partial discharge is likely to occur at the same level, the partial discharge starts to be generated from the partial discharge generating substrate portion having a larger maximum electric field strength. Insulation deterioration in the high voltage module can be detected, and based on this, measures such as replacement of the high voltage module with a new one can be taken.
[Modification of the present invention]
In each of the embodiments described with reference to FIGS. 5 to 9 described above, one semiconductor is provided on the element mounting surface metal substrate 2a bonded to the surface of the insulating substrate 1 as the main functional substrate portion in the high-voltage module. Although the configuration example in which the element 4 is mounted is shown, the high-voltage module according to the present invention is not limited to the above-described configuration, and a plurality of the same type are provided on the surface metal substrate for element mounting bonded to the surface of the insulating substrate. The present invention can also be applied to a high-voltage module having a configuration in which the semiconductor elements are mounted and a high-voltage module having a configuration in which a plurality of types of semiconductor elements are mounted on an element mounting surface metal substrate bonded to the surface of an insulating substrate.

  Moreover, in each Example demonstrated by the above-mentioned FIGS. 5-9, although all showed the structural example in which the insulated substrate of the partial discharge generation | occurrence | production board | substrate part and the insulated substrate of the main functional board | substrate part were integral components. The high-voltage module according to the present invention is not limited to the above configuration, and the insulating substrate of the partial discharge generating substrate portion and the insulating substrate of the main functional substrate portion may be separate components.

1: Insulated substrate
2: Surface metal substrate 2A: Surface metal substrate portion 2a for main functional circuit: Surface metal substrate for element mounting 2b, 2c: Surface metal substrate for relay 3: Back surface metal substrate 4: Semiconductor element 5: Gel-like insulator (silicone gel )
6: Earth plate 7: Case 8, 9: External terminal 10, 11, 12, 13, 14: Bonding wire 15: Joining member 21, 21A: Surface metal substrate for generating partial discharge 31: Current type partial discharge sensor 32: High frequency Current transformer (high frequency CT)
33: Signal processing circuit unit 41: Acoustic partial discharge sensor 42: Sound detection element 43: Signal processing circuit unit 51: Optical partial discharge sensor 52: Photodetection element 53: Signal processing circuit unit 61: Short circuit sensor 62: First Resistance (R1)
63: Second resistance (R2)
64: Potential difference measurement circuit unit 65: Signal processing circuit unit 71: Short circuit sensor 72: First resistor (R1)
73: Second resistance (R2)
74: Potential difference measurement circuit unit 75: Signal processing circuit unit 76: Current cut-off unit 77: Cut-off command signals 101, 101A, 101B, 101C, 111, 121, 131, 141, 151 1: High voltage modules 102, 112, 122, 132, 142, 152: Main functional board portions 103, 113, 123, 133, 143, 153: Substrate portions for generating partial discharge (PD generating substrate portions)
103a: insulating substrate 103b: front surface metal substrate 103c: back surface metal substrate 103d: partial discharge detection mechanism 201: high voltage power supply (HV)
301: Partial discharge (PD)
302: Dielectric breakdown (short circuit)
311: Partial discharge current 312: Partial discharge sound 313: Partial discharge light 314: Short-circuit current 321, 322, 323: Partial discharge detection signal (PD detection signal)
324, 325: Short circuit detection signal (PD detection signal)

Claims (10)

A main functional circuit surface metal substrate part for forming a main functional circuit pattern to the semiconductor element is bonded to the surface of the insulating substrate, and a back surface metal substrate to be grounded is bonded to the back surface of the insulating substrate,
In the high voltage module in which the insulating substrate, the front surface metal substrate portion for the main functional circuit, the back surface metal substrate and the semiconductor element are sealed with a gel-like insulator,
A region for main functional circuits and a region for partial discharge generation are provided on the insulating substrate,
While disposing the main functional circuit surface metal substrate portion on the surface of the main functional circuit region of the insulating substrate,
The surface metal substrate for partial discharge generation is disposed on the surface of the region for partial discharge generation of the insulating substrate separately from the surface metal substrate portion for the main functional circuit,
The main function from the surface metal substrate portion for the main function circuit, the main function circuit region of the insulating substrate, and the portion of the back surface metal substrate disposed on the back surface of the main function circuit region of the insulating substrate. While configuring the board part,
Partial discharge generation from the surface metal substrate for partial discharge generation, the partial discharge generation region of the insulating substrate, and the portion of the back metal substrate disposed on the back surface of the partial discharge generation region of the insulating substrate The board part for
The potential of the surface metal substrate for partial discharge generation is the same potential as the high potential surface metal substrate of the surface metal substrate portion for the main functional circuit,
The relationship between the distances between the end portions of the high potential surface metal substrate, the partial discharge generation surface metal substrate and the back surface metal substrate and the end portion of the insulating substrate is the maximum in the partial discharge generation substrate portion. The electric field strength is set to be larger than the maximum electric field strength in the main functional board part,
Means for detecting a partial discharge or a short circuit generated in the partial discharge generating substrate section is provided. The high pressure module according to claim 1,
The position of the end portion of the front discharge metal substrate for partial discharge generation is a position protruding from the end portion of the insulating substrate with respect to the end portion of the back metal substrate facing the insulating substrate,
A high-voltage module comprising a partial discharge detecting means for detecting a partial discharge generated on the back metal substrate side. The high pressure module according to claim 1,
The insulating substrate is made of a material having a relative dielectric constant larger than that of the gel-like insulator,
The position of the end portion of the surface metal substrate for partial discharge generation is a position that coincides with the end portion of the back surface metal substrate facing the insulating substrate, and the end portion of the surface metal substrate for partial discharge generation and the The distance from the end of the insulating substrate is the shortest of all the metal substrates bonded to the surface of the insulating substrate,
A high-voltage device comprising a short-circuit detecting means for detecting a short circuit between the front-surface metal substrate for generating partial discharge and the back-surface metal substrate generated in association with a partial discharge generated on the front-surface metal substrate for generating partial discharge. module. The high pressure module according to claim 2,
A high-voltage module comprising a current-type partial discharge sensor provided with a current detection element for detecting a current generated by the partial discharge as the partial discharge detection means. The high pressure module according to claim 2,
A high voltage module comprising an acoustic partial discharge sensor provided with a sound detection element for detecting a sound generated with the partial discharge as the partial discharge detection means. The high pressure module according to claim 2,
A high voltage module comprising an optical partial discharge sensor provided with a photodetecting element for detecting light generated by the partial discharge as the partial discharge detection means. The high pressure module according to claim 3,
A high-voltage module comprising a short-circuit sensor including a resistor through which a current due to the short circuit flows and a potential difference measurement circuit unit that measures a potential difference between both ends of the resistor as the short-circuit detecting unit. The high pressure module according to claim 7,
A high voltage module comprising a current interrupting unit in series with the resistor. The high pressure module according to any one of claims 1 to 8,
The high-voltage module, wherein the insulating substrate is made of ceramics. The high-pressure module according to any one of claims 1 to 9,
The high-pressure module according to claim 1, wherein the gel-like insulator is made of silicone gel.