Patent Publication Number: US-2023148229-A1

Title: Power unit

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to Chinese Patent Application No. 202010251552.5, titled “POWER UNIT”, filed by ATLAS COPCO (WUXI) COMPRESSOR CO., LTD., on Apr. 1, 2020, and Chinese Patent Application No. 202120366611.3, titled “Heat Sink”, filed by ATLAS COPCO (WUXI) COMPRESSOR CO., LTD., on Feb. 9, 2021, both of which are hereby incorporated by reference in their entireties. 
     FIELD OF THE INVENTION 
     The present disclosure relates to the technical field of inverters and, more particularly, to a power unit. 
     BACKGROUND OF THE INVENTION 
     In an existing inverter, a power structure needs to be mounted on a substrate and is adapted to be connected to a driving circuit board and multiple layers of busbars. However, mounting of the power structure on the substrate is not firm, and it is easy for the power structure to fall from the substrate. Thus, a fixing structure is added in some solutions, to fix the power structure on the substrate. However, in the related art, after the power structure is connected to the driving circuit board and the multiple layers of the busbars through the fixing structure, relatively long pins are required to pass through the busbars and the driving circuit board, resulting in a relatively large volume of an entire device. In addition, pins of respective power structures are likely to interfere with each other, so failures may easily occur. Moreover, when the fixing structure is used to mount the power structure on the substrate in an existing product, a process is complicated, and an installation efficiency is low. 
     SUMMARY OF THE INVENTION 
     The present disclosure aims to solve one of the above technical problems in the related art at least to a certain extent. In view of this, the present disclosure provides a power unit, which is beneficial to improve firmness of installation of the power structure on the substrate. 
     A power unit according to an embodiment of the present disclosure includes: a substrate having a first side surface at a first side thereof; a tablet structure located at the first side of the substrate; and a power structure configured to be pressed against the first side surface by the tablet structure. 
     The power unit according to the present disclosure uses the tablet structure to press the power structure against the first side surface of the substrate, thereby achieving a firm and reliable installation of the power structure on the substrate. 
     According to some embodiments of the present disclosure, the power unit further includes a first holding structure penetrating the tablet structure, in such a manner that the tablet structure is held at the first side of the substrate. 
     Furthermore, the power unit further includes a second holding structure, the second holding structure being fitted to and connected to the first holding structure, in such a manner that the tablet structure is held at the first side of the substrate. 
     Alternatively, the first holding structure is configured as a columnar structure, and the second holding structure is configured as a ring structure, with which the columnar structure is sleeved. 
     Specifically, the first holding structure is perpendicular to the first side surface and has a free end facing away from the substrate, and the first holding structure is sleeved with the second holding structure in a rotatable manner from a side of the tablet structure facing away from the substrate. 
     According to some embodiments of the present disclosure, the first holding structure is configured as a screw rod having external threads, and the second holding structure is configured as a nut having internal threads. 
     According to some embodiments of the present disclosure, the second holding structure is pressed against a side of the tablet structure facing away from the substrate. 
     According to some embodiments of the present disclosure, the tablet structure includes a tablet body formed as a recessed groove structure recessed towards the first side surface, and an opening of the tablet body faces away from the first side surface. 
     Furthermore, at least a part of the second holding structure is located in the recessed groove of the tablet body, and an end surface of the free end of the first holding structure facing away from the substrate is located in the recessed groove. 
     Specifically, the second holding structure is pressed against a tablet body bottom wall of the tablet body, the first holding structure penetrates the tablet body bottom wall, and the tablet body bottom wall is provided with a tablet body positioning hole fitted to the first holding structure. 
     According to some embodiments of the present disclosure, the tablet structure includes a tablet body and a tablet arm connected to the tablet body and configured to press the power structure. 
     Specifically, the power structure includes a first power structure and a second power structure that are spaced apart from each other. The tablet arm includes a first tablet arm and a second tablet arm. The first tablet arm is configured to press the first power structure, the second tablet arm is configured to press the second power structure, and the tablet body is located between the first power structure and the second power structure. 
     Further, the first power structure includes a first connecting leg, the second power structure includes a second connecting leg, the first connecting leg and the second connecting leg are respectively located at opposite outer sides of the first power structure and the second power structure, and the tablet body is located between opposite inner sides of the first power structure and the second power structure. 
     Alternatively, an angle between a direction along which the first connecting leg protrudes from the first power structure and a direction along which the second connecting leg protrudes from the second power structure is approximately 180 degrees. 
     According to some embodiments of the present disclosure, the first power structure and the second power structure face towards each other in a first direction of the substrate, there is a plurality of the first power structures arranged on the substrate in a second direction of the substrate, there is a plurality of the second power structures arranged on the substrate along the second direction, and there is a plurality of the tablet structures arranged along the second direction. The first direction and the second direction are perpendicular to each other. 
     Further, the plurality of the first power structures, the plurality of the tablet structures, and the plurality of the second power structures are in one-to-one correspondence in the first direction. 
     According to some embodiments of the present disclosure, the plurality of the tablet structures is connected into one piece by a tablet connecting portion. 
     Further, the tablet connecting portion is connected between tablet bodies of two adjacent tablet structures. 
     According to some embodiments of the present disclosure, the tablet structure includes a tablet body and a tablet arm. The first holding structure penetrates the tablet body, and the tablet arm is connected side by side to the tablet body in the first direction of the substrate and configured to press the power structure. There is a plurality of the tablet structures connected to each other in the second direction of the substrate, and the first direction and the second direction are perpendicular to each other. 
     Further, the tablet arms include a first tablet arm and a second tablet arm that are symmetrically connected to two sides of the tablet body. Moreover, tablet bodies of two adjacent tablet structures are connected to each other through a tablet connecting portion. 
     Specifically, the tablet body is formed as a recessed groove structure recessed towards the first side surface, an opening of the tablet body faces away from the first side surface, the first tablet arm and the second tablet arm are respectively connected to two ends of the opening of the tablet body, and the first tablet arm and the second tablet arm extend in directions facing away from each other. 
     According to some embodiments of the present disclosure, the power unit further includes: a positioning portion for positioning the power structure on the substrate. 
     According to some embodiments of the present disclosure, the positioning portion includes a positioning sheet, a through positioning opening is provided on the positioning sheet, and the positioning opening matches the power structure. 
     Alternatively, the positioning sheet is further provided with an annular positioning rib surrounding the positioning opening and matching an outer peripheral surface of the power structure. 
     According to some embodiments of the present disclosure, the positioning sheet is an insulating positioning sheet and adhesively fixed to the first side surface of the substrate. 
     According to some embodiments of the present disclosure, the positioning sheet is provided with a positioning sheet through hole for matching the first holding structure and allowing the first holding structure to pass through to form positioning fitting. 
     According to some embodiments of the present disclosure, the positioning portion includes a recess formed on the first side surface of the substrate, and the recess matches the outer peripheral surface of the power structure. 
     According to some embodiments of the present disclosure, the power unit further includes a heat-insulation structure arranged on the first side surface of the substrate in a form of surrounding the power structure. 
     According to some embodiments of the present disclosure, the first side surface of the substrate is a side surface facing towards the busbar. 
     According to some embodiments of the present disclosure, the tablet structure is configured as a seagull wing shape and includes a tablet body, a first tablet arm and a second tablet arm. The first tablet arm and the second tablet arm are symmetrically connected to two sides of the tablet body, and free ends of the first tablet arm and the second tablet arm each have a bending section bending towards the substrate. 
     The additional aspects and advantages of the present disclosure will be partly given in the following description, and some will become obvious from the following description or be learned through practice of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective assembled schematic view of a power unit; 
         FIG.  2    is an assembled side view of a power unit; 
         FIG.  3    is a perspective exploded schematic view of a power unit; 
         FIG.  4    is an exploded side view of a power unit; 
         FIG.  5    is a perspective assembled schematic view of a power unit when a ridge is provided on a substrate; 
         FIG.  6    is a perspective exploded schematic view of a power unit when a recess is provided on a substrate; 
         FIG.  7    is a perspective assembled schematic view of a power unit when a recess is provided on the substrate; 
         FIG.  8    is an assembled side view of a power unit when a recess is provided on a substrate; and 
         FIG.  9    is a perspective schematic view of a tablet structure. 
     
    
    
     REFERENCE SIGNS 
     power unit  100 , substrate  10 , ridge  11 , recess  12 , tablet structure  20 , tablet body  21 , tablet body positioning hole  211 , tablet arm  22 , first tablet arm  221 , second tablet arm  222 , tablet connecting portion  23 , bending section  24 , power structure  30 , first power structure  31 , first connecting leg  311 , second power structure  32 , second connecting leg  321 , first pin  331 , second pin  332 , third pin  333 , holding structure  45 , first holding structure  40 , second holding structure  50 , positioning sheet  60 , positioning opening  61 , annular positioning rib  62 , positioning sheet through hole  63 , and heat-insulation structure  60 ′. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The embodiments of the present disclosure will be described in detail below, examples of the embodiments are shown in the accompanying drawings, and same or similar reference numerals indicate same or similar elements or elements having same or similar functions all the way. The embodiments described below with reference to the accompanying drawings are exemplary, and intended to explain the present disclosure, but should not be understood as a limitation to the present disclosure. 
     In the description of the present disclosure, it should be understood that orientations or positional relationships indicated by the terms “longitudinal”, “lateral”, “length”, “width”, “thickness”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer” and the like are based on orientations or positional relationships shown in the drawings and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation and be constructed and operated in a specific orientation, and therefore it cannot be understood as a limitation of the present disclosure. 
     In the present disclosure, unless otherwise clearly stipulated and limited, terms such as terms “installation”, “in communication with”, “connected”, “fixed” should be understood in a broad sense, for example, it can be fixed connection, detachable connection, or integrated into one piece; it can be a mechanical connection, an electrical connection, or it can be communication with each other; it can be direct connection or indirect connection through an intermediate medium, and it can be communication of interiors of two components or an interaction relationship between two components. For those of ordinary skill in the art, the specific meaning of the above terms in the present disclosure can be understood according to specific circumstances. 
     A power unit  100  according to an embodiment of the present disclosure will be described in detail below with reference to  FIGS.  1  to  9   . 
     Referring to  FIGS.  1 - 8   , the power unit  100  according to the embodiment of the present disclosure may include: a substrate  10 , a tablet structure  20  and a power structure  30 . The substrate  10  has a first side surface a first side (i.e. an upper side in  FIG.  2   ) thereof. The tablet structure  20  is located on the first side of the substrate  10 . The power structure  30  is pressed against the first side surface of the substrate  10  by the tablet structure  20 . 
     The power unit  100  according to the embodiment of the present disclosure uses the tablet structure  20  to press the power structure  30  against the first side surface of the substrate  10 , thereby firmly and reliably mounting of the power structure  30  on the substrate  10 . 
     Referring to  FIGS.  1  to  9   , the power unit  100  further includes a holding structure  45 . The holding structure  45  includes a first holding structure  40 . The first holding structure  40  extends from the substrate  10  in a direction facing away from the first side surface, and penetrates the tablet structure  20 , in such a manner that the tablet structure  20  is held at the first side of the substrate  10  and thus the power structure  30  is held at the first side of the substrate  10  by the tablet structure  20  pressing the power structure  30 . In other words, referring to  FIGS.  2  and  8   , the first holding structure  40  penetrates the tablet structure  20  from bottom to top, and the tablet structure  20  is held at the first side of the substrate  10  by the first holding structure  40 . That is, when the first holding structure  40  penetrates the tablet structure  20 , a relative position between the tablet structure  20  and the substrate  10  is determined, and the first holding structure  40  can play a role in positioning the tablet structure  20 . 
     In some unshown embodiments, the first holding structure  40  extends towards the substrate  10  and penetrates the tablet structure  20  from top to bottom, in such a manner that the tablet structure  20  is fixed at the first side of the substrate  10 . The first holding structure  40  may be a bolt or a similar connecting structure. 
     In some other unshown embodiments, the tablet structure  20  can also be directly fixed, such as welded, on the substrate  10 , while the holding structure  45  is eliminated, thereby facilitating reducing the number of connecting components and thus reducing a weight of the power unit  100 . 
     Further, referring to  FIGS.  1  to  8   , the holding structure  45  further includes a second holding structure  50 . The second holding structure  50 , through being fitted and connected to the first holding structure  40 , makes the tablet structure  20  be held at the first side of the substrate  10 . The second holding structure  50  is connected to the first holding structure  40  at a side of the tablet structure  20  facing away from the substrate  10 . As shown in  FIG.  2   , the second holding structure  50  is connected to the first holding structure  40  at an upper side of the tablet structure  20 , and there is a wide space at an upper side of the tablet structure  20 , leaving an operation space for installation and disassembly of the second holding structure  50 . The tablet structure  20  is sandwiched between the second holding structure  50  and the substrate  10 , and the power structure  30  is sandwiched between the tablet structure  20  and the substrate  10 . 
     In the description of the present disclosure, terms “first” and “second” are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined with the “first” and “second” may explicitly or implicitly include one or more of these features. In addition, unless otherwise specifically defined, “plurality” means at least two, such as two, three, etc. 
     In the embodiment shown in  FIGS.  1  to  8   , the first holding structure  40  is configured as a columnar structure, the second holding structure  50  is configured as a ring structure, with which the columnar structure is sleeved, and the tablet structure  20  is sandwiched between the second holding structure  50  and the substrate  10 , to prevent the tablet structure  20  from being separated from the substrate  10 . 
     Specifically, the first holding structure  40  is perpendicular to the first side surface of the substrate  10 , and the first holding structure  40  has a free end far away from the substrate  10 , and the first holding structure  40  is sleeved with the second holding structure  50  in a rotatable manner from the side of the tablet structure  20  facing away from the substrate  10 , thereby facilitating a quick connection or detachment between the second holding structure  50  and the first holding structure  40 . 
     In some alternative embodiments, the first holding structure  40  is configured as a screw rod having external threads, the second holding structure  50  is configured as a nut having internal threads, and the nut is fitted to the screw rod by screwing, to facilitate installation and disassembly of the tablet structure  20 . 
     Referring to  FIGS.  1  to  8   , the second holding structure  50  is pressed against the side of the tablet structure  20  facing away from the substrate  10 , and the second holding structure  50  can exert on the tablet structure  20  a pressing force towards the substrate  10 , to prevent the tablet structure  20  from shaking, thereby leading to the more reliable connection between the tablet structure  20  and the substrate  10 . 
     Referring to  FIGS.  1  to  9   , the tablet structure  20  includes a tablet body  21  formed as a recessed groove structure recessed towards the first side surface. An opening of the tablet body  21  faces away from the first side surface. Referring to  FIGS.  2  and  4   , the tablet body  21  is formed as a recessed groove structure that is recessed downward, and the opening of the tablet body  21  faces upward. 
     Further, at least a part of the second holding structure  50  is located in the recessed groove of the tablet body  21 , and an end surface of the free end of the first holding structure  40  facing away from the substrate  10  (that is, an upper end surface of the first holding structure  40 ) is also located in the recessed groove, such that a distance between the end surface of the free end of the first holding structure  40  facing away from the substrate  10  and the substrate  10  can be shortened, and a distance between the second holding structure  50  and the substrate  10  can be shortened. Thus, the holding structure  45  is located in the recessed groove of the tablet body  21  as much as possible, which can reduce a dimension of the power unit  100  in a height direction and form a relatively large usable space above the tablet structure  20 , thereby facilitating leaving an installation space for other components and thus preventing mutual interference during the installation. 
     In an embodiment shown in  FIG.  2   , an entirety of the second holding structure  50  is located in the recessed groove, and the upper end surface of the first holding structure  40  is also located in the recessed groove, so that the dimension of the power unit  100  in the height direction can be further reduced. 
     Referring to  FIG.  2   , an overlapping dimension of the second holding structure  50  and the power structure  30  in a thickness direction of the power structure  30  exceeds half of a thickness of the second holding structure  50 , such that the second holding structure  50  can be located in the recessed groove of the tablet body  21  as much as possible, thereby further reducing the distance between the second holding structure  50  and the substrate  10 . 
     Referring to  FIGS.  1  to  3 ,  5  and  7  to  9   , the second holding structure  50  is pressed against a tablet body bottom wall of the tablet body  21 , the first holding structure  40  penetrates the tablet body bottom wall, and a tablet body positioning hole  211  fitted to the first holding structure  40  is formed in the tablet body bottom wall, so that after the first holding structure  40  penetrates the tablet body positioning hole  211  on the tablet body bottom wall, the tablet structure  20  can be preliminarily positioned, to facilitate subsequently using the second holding structure  50  to fix the tablet structure  20 . 
     Referring to  FIG.  9   , the tablet structure  20  includes a tablet body  21  and a tablet arm  22 . The tablet arm  22  is connected to the tablet body  21 . Referring to  FIGS.  1  to  2  and  5   , the tablet arm  22  is used to press the power structure  30 , and the power structure  30  is sandwiched between the tablet structure  20  and the substrate  10 . 
     Referring to  FIGS.  1  to  8   , the power structure  30  may include a first power structure  31  and a second power structure  32  that are spaced apart from each other. The tablet arm  22  includes a first tablet arm  221  and a second tablet arm  222 . The first tablet arm  221  is used to press the first power structure  31 , the second tablet arm  222  is used to press the second power structure  32 , the tablet body  21  is located between the first power structure  31  and the second power structure  32 , and the holding structure  45  is also located between the first power structure  31  and the second power structure  32 . 
     Further, the first power structure  31  includes a first connecting leg  311 , the second power structure  32  includes a second connecting leg  321 , the first connecting leg  311  and the second connecting leg  321  are respectively located on opposite outer sides of the first power structure  31  and the second power structure  32 , and the tablet body  21  is located between opposite inner sides of the first power structure  31  and the second power structure  32 . 
     Alternatively, an angle between a direction along which the first connecting leg  311  protrudes from the first power structure  31  and a direction along which the second connecting leg  321  protrudes from the second power structure  32  is approximately 180 degrees. That is, pins of the first connecting leg  311  and the second connecting leg  321  are both provided outwards, leaving a middle space between the first power structure  31  and the second power structure  32 , which allows the holding structure  45  to fix the tablet structure  20  on the substrate  10  from the middle space. 
     The pins of the first connecting leg  311  and the second connecting leg  321  each include: a first pin  331 , a second pin  332  and a third pin  333 . Each of the pins is adapted to be electrically connected to the driving circuit board or a corresponding busbar. 
     Referring to  FIGS.  2  and  4   , the first connecting leg  311  protrudes from the first power structure  31  towards left, and the second connecting leg  321  protrudes from the second power structure  32  towards right, and an angle between the two directions is approximately 180 degrees, such that it is possible to prevent an interference between the first power structure  31  and the second power structure  32  due to a relatively close distance between the first connecting leg  311  and the second connecting leg  321  when the first connecting leg  311  and the second connecting leg  321  face towards each other. Moreover, when the first power structure  31  and the second power structure  32  are connected to the corresponding busbar or driving circuit board, the first connecting leg  311  and the second connecting leg  321  both face outward, and there is plenty of space to facilitate corresponding operations. 
     Referring to  FIGS.  1 ,  3  and  5  to  7   , the first power structure  31  and the second power structure  32  are spaced apart in a first direction of the substrate  10 , for example, facing towards each other. There is a plurality of the first power structures  31  arranged on the substrate  10  in a second direction of the substrate  10 , a plurality of the second power structures  32  arranged on the substrate  10  in the second direction, and a plurality of tablet structures  20  arranged along the second direction. The first direction and the second direction are perpendicular to each other. When the substrate  10  is rectangular, the first direction may be a width direction of the substrate  10  and the second direction may be a length direction of the substrate  10 . 
     Further, the plurality of the first power structures  31 , the plurality of the tablet structures  20 , and the plurality of the second power structures  32  are in one-to-one correspondence in the first direction. A pair of oppositely arranged first power structure  31  and second power structure  32  can be pressed against the substrate  10  by the same tablet structure  20 . 
     In some embodiments, the plurality of the tablet structures  20  may be mutually independent. 
     In the embodiments shown in  FIGS.  1 ,  3  and  9   , the plurality of the tablet structures  20  is connected into one piece by a tablet connecting portion  23 , such that an assembly process of the plurality of the tablet structures  20  is saved, thereby facilitating improving an assembly efficiency of the power unit  100 . Moreover, the tablet structures  20  connected into one piece can press a plurality of the power structures  30  concurrently, leading to a high crimping efficiency. The one-piece tablet structure  20  is pressed against the substrate  10  by two or more of the holding structures  45 . 
     Further, the tablet connecting portion  23  is connected between the tablet bodies  21  of two adjacent tablet structures  20 , and a width of the tablet connecting portion  23  may be equal to a width of the tablet body  21 . 
     In the embodiment shown in  FIGS.  1 ,  3  and  9   , the tablet structure  20  includes a tablet body  21  and a tablet arm  22 . The first holding structure  40  penetrates the tablet body  21 , the tablet arm  22  is connected side by side with the tablet body  21  in the first direction of the substrate  10 , and the tablet arm  22  is used to press the power structure  30 . There is a plurality of the tablet structures  20  connected to each other in the second direction of the substrate  10 , and the first direction and the second direction are perpendicular to each other. 
     Further, the tablet arm  22  may include: a first tablet arm  221  and a second tablet arm  222  that are symmetrically connected to both sides of the tablet body  21 . In addition, the tablet bodies  21  of two adjacent ones of the tablet structures  20  are connected to each other through the tablet connecting portion  23 . 
     Referring to  FIGS.  2 ,  4 , and  9   , the tablet body  21  is formed as a recessed groove structure recessed towards the first side surface, the opening of the tablet body  21  faces away from the first side surface, the first tablet arm  221  and the second tablet arm  222  are respectively connected to two ends of the opening of the tablet body  21 , and the first tablet arm  221  and the second tablet arm  222  extend in directions facing away from each other. Referring to  FIGS.  2  and  4   , the tablet body  21  is formed as a recessed groove structure that is recessed downward, the opening of the tablet body  21  faces upward, the first tablet arm  221  extends to the left, and the second tablet arm  222  extends to the right. 
     In some alternative embodiments, the power unit  100  may further include: a positioning portion for positioning the power structure  30  on the substrate  10 , to ensure that a position of the power structure  30  on the substrate  10  is accurate, to prevent the power structure  30  from shaking randomly on the substrate  10 . 
     In the embodiments shown in  FIGS.  1  to  4   , the positioning portion includes: a positioning sheet  60 . The positioning sheet  60  is provided with a through positioning opening  61  matching the power structure  30 . For example, an outer peripheral surface of the power structure  30  and the positioning opening  61  are both rectangular, the power structure  30  is positioned in the positioning opening  61 , and a bottom of the power structure  30  is directly attached to the substrate  10 . The substrate  10  can be a metal substrate  10 , heat of the power structure  30  can be transferred to the substrate  10 , and a cooling device or a heating device may be provided under the substrate  10  to cool or heat the power structure  30 . 
     Alternatively, as shown in  FIGS.  3 - 4   , the positioning sheet  60  is also provided with an annular positioning rib  62  surrounding the positioning opening  61 , and the annular positioning rib  62  matches the outer peripheral surface of the power structure  30 . The annular positioning rib  62  protrudes from a surface of the positioning sheet  60 , so that positioning firmness of the power structure  30  can be increased, thereby leading to the better positioning effect. 
     In the embodiments shown in  FIGS.  1  to  4   , the positioning sheet  60  is an insulating positioning sheet, and the positioning sheet  60  is adhesively fixed to the first side surface of the substrate  10 . 
     Referring to  FIGS.  1  and  3   , the positioning sheet  60  is provided with a positioning sheet through hole  63  for matching the first holding structure  40  and allowing the first holding structure  40  to pass through to form positioning fitting, and after the first holding structure  40  passes through the positioning sheet through hole  63 , the positioning sheet  60  can be initially positioned. The first holding structure  40  passes through the positioning sheet through hole  63  on the positioning sheet  60  and the tablet body positioning hole  211  on the tablet body  21  to be connected to the second holding structure  50 , so as to fix the positioning sheet  60  and the tablet structure  20  between the second holding structure  50  and the substrate  10 . 
     In the embodiment shown in  FIG.  5   , the positioning portion includes a ridge  11  provided on the first side surface of the substrate  10 , thereby saving the positioning sheet  60 , which facilitates reducing the number of components while saving assembly man-hours. 
     Alternatively, the ridge  11  is a continuous annular ridge  11 , and the annular ridge  11  matches the outer peripheral surface of the power structure  30 . 
     Alternatively, the ridge  11  corresponding to each power structure  30  is divided into four sections, and the four sections are respectively located on four side surfaces of the rectangular power structure  30 , thereby limiting the power structure  30  all around, so that the power structure  30  is better positioned on the substrate  10 . 
     In the embodiment shown in  FIGS.  6 - 8   , the positioning portion includes a recess  12  formed on the first side surface of the substrate  10 , and a circumferential wall of the recess  12  is adapted to match the outer periphery surface of the power structure  30 . Preferably, the recess  12  is a blind recess. As shown in  FIG.  8   , a bottom wall of the recess  12  is adapted to be attached to a bottom surface of the power structure  30 , in order to support the power structure  30 . This embodiment also saves the positioning sheet  60 , which facilitates reducing the number of the components and saving assembly man-hours. Moreover, the recess  12  is directly provided on the first side surface of the substrate  10 , leading to simple process and strong operability. Referring to  FIG.  8   , the bottom surface of the power structure  30  is lower than the first side surface of the substrate  10 , such that a total height of the power structure  30  and the substrate  10  after assembly can be shortened, and a volume of the power unit  100  can be reduced. 
     In some alternative embodiments, the power unit  100  may further include a heat-insulation structure  60 ′ provided on the first side surface of the substrate  10  in a form of surrounding the power structure  30 . The heat-insulation structure  60 ′ is located between the power structure  30  and the substrate  10 , and the heat-insulation structure  60 ′ can separate the power structure  30  from the substrate  10 , to prevent the heat of the power structure  30  from affecting the components under the substrate  10  while preventing heat under the substrate  10  from being transferred upward to the power structure  30 . 
     In some alternative embodiments, the first side surface of the substrate  10  faces towards the busbar. 
     Referring to  FIGS.  2 ,  4 , and  9   , the tablet structure  20  is constructed as a seagull wing shape, and the tablet structure  20  may include a tablet body  21 , a first tablet arm  221 , and a second tablet arm  222 . The first tablet arm  221  and the second tablet arm  222  are symmetrically connected to both sides of the tablet body  21 , and free ends of the first tablet arm  221  and the second tablet arm  222  each have a bending section  24  bending towards the substrate  10 . The bending section  24  is adapted to press the power structure  30  so that the power structure  30  is pressed against the substrate  10 . 
     A relatively large planar space is formed above the tablet structure  20 , leaving an installation space for other components (taking the busbar as an example) while significantly reducing dimensions of the power unit  100  and the busbar assembly in the height direction. 
     In the description of this specification, the description with reference to terms “an embodiment”, “some embodiments”, “examples”, “specific examples” or “some examples” etc. means that specific features, structures, materials or characteristics described in conjunction with the embodiments or the examples are included in at least one embodiment or example of the present disclosure. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials, or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can join and combine different embodiments or examples described in this specification. 
     Although the embodiments of the present disclosure have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be construed as limiting the present disclosure, and those of ordinary skill in the art can make variations, modifications, substitutions, and modifications to the above embodiments within the scope of the present disclosure.