Patent Publication Number: US-2021194381-A1

Title: Power module assembly and converter

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims benefit of Chinese Patent Application No. 201911319707.8, filed on Dec. 19, 2019, the disclosures of which are hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to the field of power equipment, and in particular, to a power module assembly and a converter. 
     BACKGROUND 
     For currently used converters, capacitor module and power module in a power module assembly are usually designed as inseparable structures. A plurality of capacitors and Insulated Gate Bipolar Transistor (IGBT) and other components are required in the power module assembly, and the power module assembly may have a large weight up to over 100 kg. 
     The above information disclosed in the Background section is only used to enhance the understanding of the background of the present disclosure, so it may include information that does not constitute the prior art known to those of ordinary skill in the art. 
     SUMMARY 
     The present disclosure provides a power module assembly and a converter. 
     Other features and advantages of the disclosure will become apparent from the following detailed description, or may be learned in part through the practice of the disclosure. 
     According to an aspect of the present disclosure, a power module assembly is provided, including: a power module and a capacitor module; the power module and the capacitor module are configured to be detachably connected; the power module includes a first bus bar, and the first bus bar includes a first connection portion and a first installation portion connected to the first connection portion, wherein, the first connection portion extends along a first direction, and the first installation portion extends along a second direction different from the first direction; the capacitor module includes a second bus bar, and the second bus bar includes a second connection portion and a second installation portion connected to the second connection portion, wherein the second connection portion extends along the first direction, and the second installation portion extends along the second direction; the first connection portion and the second connection portion are connected by a fastener. 
     According to another aspect of the present disclosure, a converter is provided, including: the power module assembly described above. 
     It should be understood that the above general description and the following detailed description are merely exemplary, and should not limit the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features, and advantages of the present disclosure will become more apparent by describing its example embodiments in detail with reference to the accompanying drawings. 
         FIG. 1  is a schematic structural diagram of a power module assembly according to an exemplary embodiment. 
         FIG. 2  is a stereo schematic view of fastened connection between the first connection portion and the second connection portion according to an exemplary embodiment. 
         FIG. 3  is a schematic plan view of a connection of two laminated bus bars according to an exemplary embodiment. 
         FIG. 4  is a simplified schematic diagram of an internal structure of the power module assembly shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. However, the exemplary embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, providing these embodiments makes the present disclosure more comprehensive and complete, and conveys the concepts of the exemplary embodiments comprehensively to those skilled in the art. The drawings are merely schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings represent the same or similar parts, and thus repeated descriptions thereof will be omitted. 
     Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of the embodiments of the present disclosure. However, those skilled in the art will realize that the technical solutions of the present disclosure may be practiced without omitting one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other instances, well-known structures, methods, devices, implementations, or operations have not been shown or described in detail to avoid obsession and obscure aspects of the present disclosure. 
     In the present disclosure, the terms “connected” “connection”, and the like should be understood in a broad sense unless specified otherwise, for example, they may be electrically connected or coupled; they may be directly connected or indirectly through an intermediate medium connected. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to specific situations. 
     In addition, in the description of the present disclosure, the terms “first” and “second” are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as “first” and “second” may explicitly or implicitly include one or more of the features. 
     As mentioned above, for the converter currently used, the capacitor module and the power module in a power module assembly are usually designed as inseparable, which is very inconvenient for maintenance operations. Therefore, the present disclosure proposes a new power module assembly structure, which will be specifically described below through various embodiments of the present disclosure. 
       FIG. 1  is a schematic structural diagram of a power module assembly according to an exemplary embodiment. For example, the power module assembly shown in  FIG. 1  can be applied to various types of converters such as an inverter. 
     Referring to  FIG. 1 , a power module assembly  1  includes a power module  11  and a capacitor module  12 , and the power module  11  and the capacitor module  12  are configured to be detachably connected. 
     The power module  11  includes a first bus bar  111 . The first bus bar  111  includes a first connection portion  1111  and a first installation portion  1112  connected to the first connection portion  1111 . The first connection portion  1111  extends along a first direction and the first installation portion  1112  extends along a second direction, and the second direction is different from the first direction. 
     Optionally, the first connection portion  1111  and the first installation portion  1112  are vertically connected. It should be noted that, in the present disclosure, an included angle between the first connection portion  1111  and the first installation portion  1112  within a range of about 90° (for example, 90°±10°) can be equivalent to “vertical”, and the definitions of “vertical” appearing in the present disclosure are applicable to this interpretation. 
     The capacitor module  12  includes a second bus bar  121 . The second bus bar  121  includes a second connection portion  1211  and a second installation portion  1212  connected to the second connection portion  1211 , wherein the second connection portion  1211  extends along the first direction and the second installation portion  1212  extends along the second direction. 
     As above, the second connection portion  1211  and the second installation portion  1212  are optionally connected vertically. 
     In addition, the first connection portion  1111  and the second connection portion  1211  are connected by a fastener  13 . For details, refer to  FIG. 2 . 
     The fastener  13  may be, for example, a bolt, or a plug cooperates with a socket opened at a corresponding position of the first connection portion  1111  and the second connection portion  1211 . The present disclosure does not limit the specific form of the fastener  13 . 
     According to the power module assembly provided by the embodiment of the present disclosure, the capacitor module and the power module are in separable design, which facilitates separate disassembly and maintenance of the power module prone to failure. Meantime, the bus bar of the capacitor module and the bus bar of the power module are directly and tightly fastened and connected, which effectively reduces the stray inductance between the bus bars. 
     It should be clearly understood that the present disclosure describes how to make and use specific examples, but the principles of the present disclosure are not limited to any details of these examples. Rather, these principles can be applied to many other embodiments based on the teachings of this disclosure. 
     In some embodiments, both the first bus bar  111  and the second bus bar  121  may be laminated bus bars. In the following description, both the first bus bar  111  and the second bus bar  121  are described by taking a double-layer laminated bus bar as an example. 
     As described above, the first connection portion  1111  and the second connection portion  1211  are firmly connected. Optionally, as shown in  FIG. 3 , the first connection portion  1111  includes a first positive conductive layer and a first negative conductive layer, and the second connection portion  1211  includes a second positive conductive layer and a second negative conductive layer. When the first connection portion  11  and the second connection portion  1211  are connected, the first positive conductive layer, the first negative conductive layer, the second positive conductive layer, and the second negative conductive layer should be arranged in this order, or the first negative conductive layer, the first positive conductive layer, the second negative conductive layer, and the second positive conductive layer is sequentially arranged, as long as the adjacent conductive layers have opposite polarities. 
     That is, the laminated bus bars of the connection portion are arranged in the order of “positive-negative-positive-negative” or “negative-positive-negative-positive” so that currents of equal magnitude and opposite directions flow between adjacent conductive layers of the first bus bar  111  and the second bus bar  121 . Based on the principle of mutual inductance cancellation, mutual inductance between adjacent conductive layers is cancelled, mutual inductance between spaced conductive layers is strengthened, and the amount of inductance is negatively related to the distance between conductive layers. Therefore, the amount of inductance canceled by the adjacent conductive layers on the inner side is greater than the increased inductance of the spaced conductive layers, resulting in a reduction in the total inductance of the current path. Therefore, the staggered design of the bus bar polarities at the connection provided by the embodiments of the present disclosure can further reduce the stray inductance between the bus bars of the power module assembly. 
     Continuing to refer to  FIG. 1 , the capacitor module  12  further includes a plurality of DC capacitors  122 . Part of the DC capacitors  122  are installed on the front surface of the second installation portion  1212 , and the other part are installed on the reverse surface of the second installation portion  1212 . Optionally, the DC capacitors  122  are evenly distributed on the front and rear sides of the second installation portion  1212  in an array. It should be noted that, in some embodiments, the DC capacitors  122  on the front and rear sides of the second installation portion  1212  may be equal or substantially equal in number, and in structure, in order to allow all the DC capacitors  122  to be connected to the second installation portion  1212 , the DC capacitors  122  on the front and rear sides may be staggered. 
     According to the power module assembly provided by some embodiments of the present disclosure, the DC capacitors are divided into two groups, which are respectively arranged on the front and rear sides of a capacitor bus bar, which greatly reduce the area of the capacitor bus bar, thereby lowering the center of gravity of the capacitor bus bar and reducing the overall height, and making the structure of the power module assembly more compact, while reducing the stray inductance between the capacitor module and the power module, thereby reducing the off-voltage stress of the IGBT in the power module. 
     Refer to  FIG. 1 , the power module  11  further includes a three-phase IGBT module  112  connected to the first installation portion  1112 . The three-phase IGBT module  112  includes: a first phase sub-module  1121 , a second phase sub-module  1122 , and a third phase sub-module  1123 . Optionally, the second phase sub-module  1122  is a middle phase sub-module of the three-phase IGBT module  112 . 
     Optionally, as shown in  FIG. 4 , in the first installation portion  1112 , the length of the portion “a” connected to the second phase sub-module  1122  (not shown in  FIG. 4 ) is greater than the length of the portion “b” connected to the first phase sub-module  1121  (not shown in  FIG. 4 ) and the third phase sub-module  1123  (not shown in  FIG. 4 ). 
     According to the power module assembly provided by some embodiments of the present disclosure, the installation part connected to the middle-phase sub-module is appropriately lengthened so that the equivalent current paths of the three-phase sub-modules to the DC capacitors are the same or basic the same, thereby ensuring that the stray inductances of the current path between the three-phase sub-modules and the DC capacitors are relatively consistent, effectively balancing the electrical stress between the three-phase sub-modules and the ripple current of the DC capacitors. 
     As shown in  FIG. 4 , in order to make the length of “a” greater than the length of “b”, the first installation portion  1112  may include a first extension portion  1112 ′ connected to the first connection portion  1111 , and a third connection portion  1112 ″, and a second extension portion  1112 ′″ connected to the third connection portion  1112 ″; wherein, the first extension portion  1112 ′ and the second extension portion  1112 ′″ both extend along a second direction, and the third connection portion  1112 ″ extends along a first direction. In addition, the third connection portion  1112 ″ which is coplanar with the first connection portion  1111 , is connected to the second connection portion  1211  by the fastener  13 , the second phase sub-module  1122  is connected to the second extension portion  1112 ′″, and the first phase sub-module  1121  and the third phase sub-module  1123  are connected to the first extension portion  1112 ′. 
     As shown in  FIG. 1 , the power module  11  further includes a heat dissipation device  113  disposed in parallel with the first installation portion  1112 . It should be noted that, in the present disclosure, the included angle between the heat dissipation device  113  and the first installation portion  1112  in the range of about 0° (for example, 0°±15°) can be equivalent to “parallel”, and the definitions of “parallel” in the present disclosure are applicable to this interpretation. 
     The heat dissipation device  113  is configured to dissipate heat from the three-phase IGBT module  112 . Further, the three-phase IGBT module  112  may be disposed between the heat dissipation device  113  and the first installation portion  1112  to directly transfer heat generated by the three-phase IGBT module  112  through the heat dissipation device  113 . 
     Wherein, an optional embodiment of the heat dissipation device  113  is a water-cooled plate. While the heat dissipation device  113  may also be another type of cooling device, which is not limited in the present disclosure. 
     In the embodiment shown in  FIG. 1 , the first phase sub-module  1121  and the third phase sub-module  1123  are both disposed on one side of the heat dissipation device  113 , and the second phase sub-module  1122  is disposed on the other side of the heat dissipation device  113 . 
     According to the power module assembly provided by some embodiments of the present disclosure, the three-phase IGBT modules are distributed on both sides of the heat dissipation device, which significantly reduces the height of the power module assembly, reduces the maintenance difficulty, and improves the power density of the power module assembly. 
     As shown in  FIG. 1 , the power module assembly  1  further includes: a sheet metal structure  14  and a positioning component  15 . The sheet metal structure  14  includes a first sheet metal structure  141  (not completely shown in the figure) and a second sheet metal structure  142 . The first sheet metal structure  141  surrounds the power module  11 , and the second sheet metal structure  142  surrounds the capacitor module  12 . The positioning component  15  may be, for example, a positioning pin for positioning the first sheet metal structure  141  and the second sheet metal structure  142  to ensure that the power module  11  and the capacitor module  12  are aligned and reliably connected, which is helpful for the fastener  13  to fasten the first connection portion  1111  and the second connection portion  1211 . 
     Alternatively, as shown in  FIG. 1 , the positioning component  15  may be disposed at two ends where the first sheet metal structure  141  and the second sheet metal structure  142  joint. 
     Following the above, the power module assembly  1  shown in  FIG. 1  can be applied to various types of converters such as an inverter or a wind power converter. The converter includes a power module assembly  1  and a cabinet (not shown) in which the power module assembly  1  is loaded. The cabinet door is disposed on the operable side of the fastener  13  to facilitate maintenance personnel from the cabinet. Relevant operations are performed on the fastener  13  on the front side, thereby facilitating separate disassembly and maintenance of the power module  11  which is prone to failure. 
     According to the converter provided by the embodiment of the present disclosure, by referring to  FIG. 1 : when removing the power module assembly  1 , the maintenance personnel opens the cabinet door (located on the front of the cabinet, perpendicular to the direction indicated by arrow A), and removes the fastener  13  (located on the first connection portion  1111 ) to separate the power module  11  from the capacitor module  12 , then the power module  11  and the capacitor module  12  can be taken out of the cabinet in the opposite direction indicated by the arrow A; otherwise, when installing the power module assembly  1 , the maintenance personnel can place the capacitor module  12  and the power module  11  in the cabinet in the direction indicated by the arrow A, and install the fastener  13  so that the power module  11  and the capacitor module  12  are fixedly connected. Therefore, disassembly and assembly can be completed through the cabinet door on the front of the cabinet, and no other orientation of the cabinet is needed, which effectively reduces the maintenance difficulty of the converter. 
     According to the power module assembly provided by the present disclosure, the capacitor module and the power module have a separable design, which facilitates separate disassembly and maintenance of the power module that is prone to failure. Meanwhile, a bus bar of the capacitor module and a bus bar of the power module are directly and tightly fastened and connected, which effectively reduces stray inductance between the bus bars. 
     The exemplary embodiments of the present disclosure have been specifically shown and described above. It should be understood that the disclosure is not limited to the detailed structure, arrangement or implementation methods described herein; rather, the disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.