RU2757166C1 - Diode for rotary rectifier of synchronous electric machine - Google Patents

Abstract

FIELD: electrical machines.

SUBSTANCE: invention relates to the field of brushless synchronous electrical machines containing rotating rectifiers, and more specifically to semiconductor diodes used in rotating rectifiers, in which the semiconductor element is enclosed in a sealed housing. A diode for a rotary rectifier comprises a semiconductor element, a base, a dome-shaped element, an electrode terminal, and an insulating element. The semiconductor element is located in an enclosed space between the base and the dome element. The electrode lead, dome, semiconductor, and base, in that order, are elements of the electrical circuit of the diode. The insulating element prevents direct electrical contact between the dome and the base. In this case, the dome-shaped element is connected to the electrode terminal in its dome section and connected to the semiconductor element in its edge section.

EFFECT: increasing the reliability of sealing the enclosed space in which the semiconductor element is located, as well as in increasing the reliability of the electrical contact between the semiconductor element and the electrode terminal.

10 cl, 5 dwg

Description

Technology area

[1] The invention relates to the field of electrical engineering, in particular, to brushless synchronous electric machines containing rotating rectifiers, and more specifically to semiconductor diodes used in rotating rectifiers, in which the semiconductor element is enclosed in a sealed housing.

[2] In the context of the present invention, an electrical machine is understood to mean an electromechanical device for converting mechanical energy into electrical energy and vice versa, namely generators of electric current and electric motors. Paying attention to the fact that the invention can be used in any of the specified electrical machines, the inventors believe that the main direction for using the invention is electric current generators, namely, brushless high-speed synchronous generators, mainly intended for use in power supply systems for aircraft ...

Background to the invention

[3] Diodes used in rotating rectifiers of high speed synchronous generators require efficient cooling, which is achieved by creating a liquid-air atmosphere around the diodes. The combination of such factors affecting the diodes as a significant centrifugal force due to the high frequency of rotation of the rectifier, the chemical activity of the coolant, temperature differences, etc. can lead to depressurization of the diode body or to the interruption of the electrical circuit between the semiconductor element and the electrode terminal, which leads to the inevitable failure of the diode.

[4] Patent publication CN 204130550 U, 01.28.2015 discloses a diode in which a semiconductor element attached to a base is disposed in an enclosed space between the base and the dome-shaped element. The semiconductor element is connected to an electrode lead emerging from the enclosed space through the central opening of the dome-shaped element. An insulating element preventing electrical contact between the electrode lead and the dome-shaped element is installed in the said central hole and is made in the form of a rubber sleeve. The insulating element also performs the following functions:

- a seal between the electrode lead and the domed element to seal the enclosed space,

- a damper that allows small deviations of the electrode terminal from the vertical position without destroying the seal and the resulting depressurization of the enclosed space.

[5] One of the disadvantages of the above-described diode is the poor longitudinal fixation of the electrode terminal on the domed element. As a result, when even a small force is applied to the electrode terminal, acting in the axial direction of the diode, the electrode terminal can easily come off the semiconductor element, and the electrical contact between them will be interrupted.

[6] In addition, when such a diode is used in a rotating rectifier, the centrifugal force will compress the elastic insulating element towards the side of the central hole that is radially external to the axis of rotation of the diode, which will lead to a weakening of the seal on the opposite side of the central hole and depressurization of the enclosed space. Note that the diode of a rotating rectifier, as a rule, is installed so that its longitudinal axis is displaced relative to the axis of rotation of the diode, which coincides with the axis of the electric machine shaft.

[7] In patent publication RU193911U1, 11/21/2019, a diode is disclosed, the design of which is generally similar to that described above with the main difference that the insulating element is made of glass. Since the insulating element in this diode is solid, then it is not squeezed out from the central hole of the dome-shaped element from the side of the axis of rotation of the diode. At the same time, in this diode, longitudinal fixation of the electrode lead on the dome-shaped element can be provided.

[8] However, this diode has a significant drawback, which is due to the fragility of the glass and the small size of the area of the insulating element that contacts the electrode terminal in any transverse direction of the diode. In view of the latter circumstance, any effect on the electrode terminal in the transverse direction of the diode is accompanied by the appearance of a stress concentration in the insulating element, and since the insulating element is made of a brittle material, the stress concentration can cause cracking of the insulating element, loss of tightness of the closed space and diode failure.

[9] The technical problem to be solved by the invention is the development of such a diode design for a rotating rectifier, which could simultaneously increase:

- reliability of sealing the enclosed space in which the semiconductor element is located,

- reliability of electrical contact between the semiconductor element and the electrode terminal.

The essence of the invention

[10] To solve this technical problem, a diode for a rotary rectifier is proposed as an invention comprising a semiconductor element, a base, a dome-shaped element, an electrode terminal and an insulating element. The semiconductor element is located in an enclosed space between the base and the dome element. The electrode lead, dome, semiconductor, and base, in that order, are elements of the electrical circuit of the diode. The insulating element prevents direct electrical contact between the dome and the base. In this case, the dome-shaped element is connected to the electrode terminal in its dome section and connected to the semiconductor element in its edge section.

[11] The technical result of the invention is that any transverse effect on the electrode terminal is distributed through the extended edge portion of the dome-shaped element over a large area of the insulating element, which means that the stress concentration that can cause the destruction of the insulating element does not occur. In addition, the electrode lead has a rigid attachment and reliable electrical contact with the dome-shaped element without finding any intermediate elements made of fragile or elastic materials between them. In turn, the electrical connection between the dome-shaped element and the semiconductor element is provided within a protected enclosed space. As a result, no random or predictable lateral or longitudinal action on the electrode terminal is capable of disrupting the electrical continuity between the semiconductor element and the electrode terminal.

[12] In the first particular case of the invention, the dome-shaped element has a central hole, and the electrode lead is made in the form of a mushroom-shaped insert containing pin and disc portions, while the disc portion of the electrode lead is attached to the inner surface of the dome-shaped element, and the pin portion of the electrode lead passes through the central opening of the domed element. This particular case allows you to maximize the mechanical strength and tightness of the bonding of the electrode lead and the domed element.

[13] In the second particular case of the invention, the base has a pedestal and support surfaces that face the dome-shaped element and lie in planes that run perpendicular to the longitudinal axis of the diode. A semiconductor element is placed on the pedestal surface, and the support surface serves as a support for the dome-shaped element. In this case, the insulating element is located between the support surface and the edge section of the dome-shaped element. This particular case makes it possible to ensure the optimal mutual arrangement of the semiconductor element and the edge section of the dome-shaped element from the point of view of the manufacturability of the electrical connection between them.

[14] In the development of the second special case, the insulating element is made in the form of a ceramic ring. Due to the fact that ceramics have an extremely high electrical resistance, this design eliminates the flow of electric current directly between the dome and the base. In addition, due to the high rigidity of the ceramics, this design allows the insulating element and the base to be tightly pressed against each other, as well as the dome-shaped element and the insulating element when they are bonded, which contributes to the strength of the bonding and ensures the specified accuracy of the relative position of these elements. Further, the ceramics are highly heat-resistant, which makes it possible to apply high-temperature processing and assembly methods.

[15] In another development of the second special case, the base has rod and flange elements, while the pedestal surface is located on the end surface of the rod element, and the support surface is located on the end surface of the flange element. In this embodiment, the diode, by means of its flange element, can be supported, for example, on the radiator of a rotating rectifier.

[16] At the same time, the specified rod element may be the first rod element, and the specified end surface of the flange element may be the first end surface of the flange element. In the latter case, the base contains a second rod element, which with respect to the first rod element is located on the side of the second end surface of the flange element, and a thread is made on the side surface of the second rod element. This design makes it possible to fasten the diode to the radiator of the rotating rectifier by means of a threaded connection, ensuring reliable electrical contact.

[17] In another development of the second particular case, an electrically conductive coating is formed on the surface of the insulating element facing the dome-shaped element, which is electrically connected to the semiconductor element. The edge portion of the domed element is in this case in electrical contact with the electrically conductive coating of the insulating element. This design allows the electrical connection between the dome-shaped element and the semiconductor element to be made directly on the insulating element, which has a high thermal resistance and which is not further exposed to direct thermal effects when performing high-temperature welding. As a result, the reliability of the electrical circuit between the semiconductor element and the dome element is improved.

[18] In the latter embodiment, the electrical connection between the electrically conductive coating of the insulating element and the semiconductor element can be made using wire elements. This design makes it possible to provide an electrical connection between the spaced-apart semiconductor element and the electrically conductive coating of the insulating element in a simple and reliable way.

[19] In another development of the second special case, between the insulating element and the supporting surface of the base there is a washer made of a material, the coefficient of thermal expansion of which lies in the range between the coefficients of thermal expansion of the base materials and the insulating element. This design makes it possible to smooth out the mutual displacement of the base and the insulating element caused by the difference in their coefficients of thermal expansion, and thereby prevent cracking of the insulating element when performing high-temperature brazing to fix the insulating element on the base.

[20] In another development of the second special case, a conductive washer is placed between the insulating element and the edge portion of the dome-shaped element. This design allows the dome-shaped element to be attached to the insulating element using seam-roller or pulsed laser welding.

Brief Description of Drawings

[21] The implementation of the invention will be explained with reference to the figures:

FIG. 1 - diode made according to the invention, longitudinal section;

FIG. 2 is a perspective view of a diode according to the invention;

FIG. 3 - diode base with installed thermal compensation washer and insulating element, isometric view;

FIG. 4 - diode base with installed thermal compensation washer, insulating element and semiconductor element, isometric view;

FIG. 5 - diode base with an insulating element, a semiconductor element and a conductive washer installed with a thermal compensation washer, isometric view.

[22] The shape and size of the individual elements shown in the figures are conditional and shown so as to most clearly illustrate the relative position of the diode elements and their causal relationship with the claimed technical results.

Implementation of the invention

[23] The implementation of the invention will be shown on the best known to the authors examples of the implementation of the invention, which are not restrictions on the scope of protected rights.

[24] The rotary rectifier diode 1 shown in FIG. 1 and 2, comprises a semiconductor element 10, a base 20, a dome-shaped element 30, an electrode terminal 40, an insulating element 50, a thermal expansion washer 60 and a conductive washer 70. The electrode terminal 40, a dome-shaped element 30, a semiconductor element 10, and a base 20, in this order, are elements of the electric circuit of the diode, in which the semiconductor element 10 is capable of passing electric current only in the direction from the electrode terminal 40 to the base 20.

[25] The base 20 is made of gold-plated copper and is a coaxial first rod element 21, a flange element 22 and a second rod element 23, made in one piece. The flange member 22 has first and second support portions 221 and 225 (FIG. 2), with the first and second rod members 21 and 23 located on the side of the first and second support portions 221 and 225, respectively.

[26] On the first support portion 221, there is a first end surface 222 of the flange element 22, comprising a first support surface 223 (FIG. 1) through which the base 20 is rigidly connected to the dome-shaped element 30. On the first support surface 223, by soldering with a silver solder, carried out at a temperature of 830-870 ° C in a reducing environment, a thermocompensating washer 60 is fixed, made of a molybdenum-copper alloy with a nickel coating, and an insulating element 50, made in the form of a ceramic ring and hereinafter referred to as an insulating ring 50, is fixed on top of it in the same way ...

[27] The insulating ring 50 is made of radio-technical corundum ceramics with subsequent metallization of its flat surfaces by applying molybdenum paste and firing it at a temperature of 830-850 ° C. In addition, the surfaces of the insulating ring 50 metallized in this manner are nickel-plated. Due to the properties of this ceramic material, the insulating ring 50 made from it has high rigidity and heat resistance, which allows the use of high-temperature processing and installation methods.

[28] Molybdenum-copper alloy has a coefficient of thermal expansion that is intermediate between those for copper, which has a large value, and for ceramics, which has a small value. Accordingly, securing the insulating ring 50 to the copper flange member 22 through the molybdenum-copper thermal expansion washer 60 avoids cracking the insulating ring 50 caused by the significant relative increase in the size of the first support portion 221 during high temperature brazing.

[29] Since the ceramic is a dielectric, the insulating ring 50 is an insulating element that does not allow electric current to flow between the below-described edge portion 33 of the dome-shaped element 30 and the flange element 22. However, on the surface 51 of the insulating ring 50, which is opposite to the surface in contact with thermocompensating washer 60 (Fig. 3), applied electrically conductive coating 52.

[30] On the second support portion 225 is a second end surface 226 of the flange member 22 including a second support surface 227 (FIG. 1) through which the base 20 bears on the rotary rectifier radiator.

[31] The radial surface 224 of the first bearing portion 221 is a cylindrical surface, while the radial surface 228 of the second bearing portion 225 is a prismatic surface with a hexagonal cross-section (FIG. 2).

[32] The first rod element 21 at its end surface has a pedestal surface 211 (Fig. 3) intended for fixing the semiconductor element 10 (Fig. 4) thereon. It should be noted that the cross-sectional shape of the first rod element 21, as well as the shape of the pedestal surface 211, correspond to the shape of the semiconductor element 10, and are square in the diode 1.

[33] The second rod element 23 has a cylindrical side surface 231 (Fig. 3), which is threaded (Fig. 1), allowing the base 20 to be fastened to the radiator of the rotary rectifier by means of a threaded connection to ensure reliable electrical contact. Tightening of this threaded connection occurs through the prismatic radial surface 228 of the second bearing portion 225.

[34] The dome-shaped element 30 is a thin-walled shell made of nickel and contains a dome portion 31 with a circular central opening 32 (Fig. 1, not shown in Fig. 2) and a flat edge portion 33 running perpendicular to the longitudinal axis of the dome-shaped element 30 (Fig. 1, 2). The dome portion 31 is understood to mean that portion of the dome-shaped element 30 which faces the enclosed space 35 described below, i. E. essentially the entire dome 30 except for the edge portion 33.

[35] Connected to the dome 30 is an electrode lead 40 made of nickel-plated copper. The electrode lead 40 is made in the form of a mushroom-shaped insert, which contains a disc section 41 and a cylindrical pin section 42 (not shown in Fig. 2). The pin portion 42 is passed into the central hole 32, and the disc portion 42 is attached to the inner surface of the dome portion 31 along its entire perimeter by soldering with silver solder carried out at a temperature of 830-870 ° C in a reducing environment. As a result, a strong connection is formed between the dome 30 and the electrode lead 40, sealing the opening 32 and providing reliable electrical contact. The upper part of the pin portion 42 is flattened to form a through hole and constitutes the contact portion 43. At the end of the assembly process, the dome 30 and the electrode terminal 40 are gold plated.

[36] The semiconductor element 10 is fixed to the pedestal surface 211, for example by eutectic soldering, such that electrical contact is provided between the first rod element 21 and the semiconductor element 10. Meanwhile, the semiconductor element 10 is connected by means of aluminum wire elements 11 to the electrically conductive coating 52 of the insulating ring 50. Note that in the preferred case the electrically conductive coating 52 and the pedestal surface 211 lie in the same plane, as shown in FIG. 1 and 4.

[37] Further, on the electrically conductive coating 52 of the insulating ring 50 by soldering with a silver solder carried out at a temperature of 830-870 ° C in a reducing environment, a conductive washer 70 (Fig. 1 and 5), made of a molybdenum-copper alloy with a nickel coated. In turn, on the conductive washer 70, the edge section 33 of the dome-shaped element 30 is fixed (Fig. 1 and 2), while between the electrically conductive coating 52 of the insulating ring 50 and the conductive washer 70, as well as between the conductive washer 70 and the edge section 33 of the dome-shaped element 30 electrical contact is provided.

[38] The placement of the conductive washer 70 between the dome 30 and the insulating ring 50 allows the use of seam or pulsed laser welding to attach the dome 30 to the base 20, which would not be possible with the direct connection of the dome 30 and the insulating ring 50. This view welding ensures tightness of the connection and reliable electrical contact between the elements to be connected.

[39] It should be noted that the material of the conductive washer 70 (molybdenum-copper alloy) has a coefficient of thermal expansion that is intermediate between that of the materials of the dome element (nickel) and the insulating ring 50 (ceramic). Accordingly, in addition to the above, the conductive washer 70 has the same function as the thermal expansion washer 60, namely, to prevent the insulating ring 50 from cracking due to a significant relative increase in the size of the edge portion 33 of the dome 30 during high temperature welding.

[40] In the context of the present disclosure, the terms "elements are rigidly connected to each other", "elements are rigidly attached to each other" and the like. mean such a mutual relationship between any two elements in which these elements represent one whole or, in other words, a single body, even if any intermediate elements are located between these elements. Thus, in the diode 1, the dome-shaped element 30 is rigidly fixed on the base 20 with support on its first supporting surface 223, this fixing is carried out through the conductive washer 70, the insulating ring 50 and the thermal expansion washer 60. As a result, between the dome-shaped element 30 and the base 20, a closed space 35 (FIG. 1) is formed, in which the semiconductor element 10 is placed.

[41] In the context of the present disclosure, the term "electrically connected to each other" used in relation to any two elements means that these two elements are included in the electrical circuit of the diode, while other elements may be included between the two elements. Thus, the feature "the dome-shaped element 30 is connected to the semiconductor element 10 at its edge portion 33" includes the above-described configuration when the conductive washer 70, the electrically conductive coating 52 and the wire elements 11 are electrically connected between the edge portion 33 and the semiconductor element 10 ...

[42] In the context of the present disclosure, the term "have direct electrical contact with each other", used in relation to any two elements, means that these two elements are included in the electrical circuit of the diode, while there is no another of the elements of the electrical circuit of the diode, namely: an electrode terminal, a dome-shaped element, a semiconductor element, and a base. Thus, the dome-shaped element 30 does not have direct electrical contact with the base 20, since either a semiconductor element 10 is included in the electric circuit of the diode between them, or there is no electrical circuit due to the dielectric properties of the insulating ring 50 located between the dome-shaped element 30 and the base 20.

[43] Further, the insulating ring 50 need not be made of ceramic. However, other known solid and heat-resistant dielectric materials are also quite hard and brittle, such as glass in the above-described known solution. However, regardless of the material chosen for the production of the insulating ring 50, due to the large contact area of the conductive washer 70 and the insulating ring 50, any mechanical influences transmitted from the electrode terminal 40 to the insulating ring 50 through the dome-shaped element 30 are distributed over a large area of the insulating ring 50, which means that no stress concentration arises in the material of the insulating ring 50 that can cause the destruction of the insulating ring 50.

[44] Note also that the electrical connection of the semiconductor element 10 with the electrically conductive coating 52, made by the wire elements 11, is located inside the enclosed space and is protected by the dome-shaped element 30. Due to this, and also taking into account the extended and reliable fastening of the dome-shaped element 30 and the insulating ring 50, any mechanical action on the electrode terminal 40 does not create a risk of interrupting the electrical connection between the electrode terminal 40 and the semiconductor element 10, which is a fundamental difference between the diode 1 and the known solutions.

[45] Further, in the diode 1, an electric current flows through the dome portion 31 of the dome 30, i. E. the outer surface of diode 1 is energized. However, this does not call into question the safety of using diode 1 in view of the fact that diode 1 is intended for use in a rotating rectifier that is located inside the housing of a synchronous electric machine. In addition, the electric current passing through the diode 1 can occur only under the condition of rotation of the shaft on which the diode 1 is fixed, and under these conditions no physical contact with the diode 1 is possible.

[46] It should be noted that in the diode 1, the dome portion 31 of the dome-shaped element 30 has the shape of a flat cylinder closed at the top, which allows the disk portion 42 of the electrode lead 40 to be securely and hermetically secured, as well as to provide sufficient volume and optimal configuration of the closed space 35. However, less, the dome portion 31 of the dome 30 can be of any shape, provided that the enclosed space 35 formed by the connection of the dome 30 to the base 20 is able to accommodate the semiconductor element 10, the wire elements 11 and the portion of the electrically conductive coating 52 sufficient for the attachment of the wire elements. 11. For example, the dome portion 31 may also have the shape of a hemisphere, a truncated cone, a truncated pyramid, a high cylinder closed at the top, a prism closed at the top, or some other shape.

Claims (15)

1. A diode for a rotating rectifier containing a semiconductor element, a base, a dome-shaped element, an electrode terminal and an insulating element, and the semiconductor element is located in a closed space between the base and the dome-shaped element, while the electrode terminal, domed element, semiconductor element and base in this order are elements of the electrical circuit of the diode, and the insulating element prevents direct electrical contact between the domed element and the base, wherein the dome-shaped element is connected to the electrode terminal at its dome portion and is connected to the semiconductor element at its edge portion. 2. The diode according to claim 1, in which the dome-shaped element has a central hole, and the electrode terminal is made in the form of a mushroom-shaped insert containing pin and disc sections, while the disc portion of the electrode lead is attached to the inner surface of the dome, and the pin portion of the electrode lead passes through the central hole of the dome. 3. The diode according to claim 1, in which the base has a pedestal and support surfaces that face the dome-shaped element and lie in planes passing perpendicular to the longitudinal axis of the diode, and a semiconductor element is placed on the pedestal surface, and the abutment surface supports the dome-shaped element, the insulating element being disposed between the abutment surface and the edge portion of the dome-shaped element. 4. The diode according to claim 3, wherein the insulating element is made in the form of a ceramic ring. 5. The diode according to claim 3, wherein the base has rod and flange elements, wherein the pedestal surface is located on the end surface of the rod element, and the support surface is located on the end surface of the flange element. 6. The diode according to claim 5, in which said rod element is the first rod element, and said end surface of the flange element is the first end surface of the flange element, and the base comprises a second rod element, which is located on the side of the second the end surface of the flange element, and a thread is made on the side surface of the second rod element. 7. The diode of claim. 3, wherein the surface of the insulating element facing the domed element is provided with an electrically conductive coating that is electrically connected to the semiconductor element, the edge portion of the domed element being in electrical contact with the electrically conductive coating of the insulating element. 8. The diode of claim. 7, wherein the electrical connection between the electrically conductive coating of the insulating element and the semiconductor element is made using wire elements. 9. The diode according to claim 3, in which a washer is placed between the insulating element and the supporting surface of the base, made of a material, the coefficient of thermal expansion of which lies in the range between the coefficients of thermal expansion of the base materials and the insulating element. 10. A diode according to claim 3, wherein a conductive washer is disposed between the insulating element and the edge portion of the dome-shaped element.

Images