Frequency converter

Abstract

The utility model relates to a frequency converter, the frequency converter comprises a housing assembly and a mounting plate, the mounting plate is connected with the inner wall of the housing assembly to divide the internal space of the housing assembly into a heat radiation chamber and an element chamber which are located at the two sides of the mounting plate, a heat radiator is installed in the heat radiation chamber, and electrical and electronic components are installed in the element chamber. The shell assembly comprises a shell part which defines a heat dissipation cavity together with the mounting plate, the shell part comprises a back plate and a peripheral wall, the back plate is arranged opposite to the mounting plate, the peripheral wall extends to the back plate towards one side of the heat dissipation cavity around the periphery of the mounting plate, and the back plate is detachably mounted on the peripheral wall and is separated from the radiator. According to the frequency converter provided by the utility model, the radiating chamber and the radiator can be exposed to clean dust only by simply detaching the backboard from the frequency converter without detaching the radiator, electrical and electronic components or other structures, so that the cleaning process is very simple and convenient; and possible damage to the frequency converter and elements thereof caused by dismounting the frequency converter is avoided.

Description

TECHNICAL FIELD

[0001] The utility model relates to frequency converter technical field especially is related to a frequency converter with improved casing structure. BACKGROUND

[0002] The frequency converter is the application frequency conversion technology and microelectronic technology, through changing AC motor operating voltage's frequency and amplitude to smooth control AC motor's speed and torque power control equipment. Frequency converter can provide the power supply voltage required by motor according to the actual need, and further reach the purpose of energy saving, speed regulation. In addition, frequency converter also has many protection functions such as overcurrent, overvoltage, overload protection. With the continuous improvement of industrial automation degree, frequency converter has been very widely used.

[0003] The frequency converter is mainly composed of rectification (AC to DC) unit, filter unit, inverter (DC to AC) unit, braking unit, driving unit, detection unit, micro-processing unit etc., these units contain various electrical and electronic components, typically such as IGBT. Therefore, the frequency converter will generate a large amount of heat from these electrical and electronic components during use, and the cooling fan blowing cooling air through the radiator is the common cooling method of frequency converter.

[0004] In the prior art, the heat dissipation channel equipped with radiator and fan is designed in the interior of frequency converter. Due to the large amount of air, dust is easy to accumulate in the heat dissipation channel, for example, blocked between the fins of the radiator, resulting in poor heat dissipation effect, and further affecting the performance and life of the frequency converter. However, due to the complex structure or components around the heat dissipation channel, it is often difficult to open the frequency converter for dust removal, for example, in some frequency converter designs, many electrical and electronic components including circuit boards and the like need to be removed first to expose the heat dissipation channel for cleaning. In addition, even if the frequency converter is opened by disassembling the electrical and electronic components, it is easy to cause damage to the frequency converter and its components. SUMMARY

[0005] The utility model aims at solving at least one of the above problems and / or other defects in the prior art.

[0006] To achieve the above object, the utility model provides a kind of frequency converter, the frequency converter includes shell assembly and mounting plate, the mounting plate is connected with the inner wall of the shell assembly to separate the internal space of the shell assembly into heat dissipation chamber and element chamber located at the both sides of the mounting plate, the radiator of the frequency converter is installed in the heat dissipation chamber, and the electrical and electronic elements of the frequency converter are installed in the element chamber.The shell assembly includes the shell part that defines the heat dissipation chamber with the mounting plate, the shell part includes the back plate that is oppositely arranged with the mounting plate and the peripheral wall that extends to the back plate on the side of the heat dissipation chamber around the periphery of the mounting plate, and the back plate is detachably mounted on the peripheral wall and is spaced apart from the radiator.

[0007] According to an embodiment of the utility model, a fan facing the radiator is further arranged in the heat dissipation chamber, and an air inlet and an air outlet are arranged on the peripheral wall to form an air duct in the heat dissipation chamber, which extends from the air inlet to the air outlet via the fan to blow cooling air through the radiator.

[0008] According to an embodiment of the utility model, the peripheral wall is in the form of a rectangular frame body including two oppositely arranged short walls and two oppositely arranged long walls, and the two short walls are respectively composed of an air inlet cover plate with an aperture serving as the air inlet and an air outlet cover plate with an aperture serving as the air outlet.

[0009] According to an embodiment of the utility model, at least one wall of the two short walls and the two long walls of the peripheral wall is detachably connected in the frequency converter.

[0010] According to an embodiment of the utility model, a first groove recessed towards the heat dissipation chamber from the back plate facing the radiator is arranged on the back plate to reduce the gap between the back plate and the radiator at the recessed position.

[0011] According to an embodiment of the utility model, the frequency converter includes a heating device extending from the element chamber to the heat dissipation chamber through the mounting plate towards the back plate, and the heating device is arranged in the air duct in parallel with the radiator in a direction transverse to the cooling air.

[0012] According to an embodiment of the utility model, one or more second grooves recessed towards the heat dissipation chamber from the back plate facing the heating device are arranged on the back plate to reduce the gap between the back plate and the heating device at the recessed position.

[0013] According to an embodiment of the utility model, a reinforcing rib is arranged in at least one of the second grooves.

[0014] According to an embodiment of the utility model, the heating device includes a plurality of capacitors.

[0015] According to an embodiment of the present application, the back plate is detachably mounted on the peripheral wall via a snap structure or fastener.

[0016] In the frequency converter according to the present application, a part of the housing assembly (housing part) together with a mounting plate connected in the housing assembly defines a heat dissipation chamber, the housing part comprising a back plate oppositely arranged with the mounting plate, the back plate being detachably mounted in the housing part or the frequency converter and being spaced apart from a heat sink arranged in the heat dissipation chamber. Therefore, when it is necessary to clean dust in the heat dissipation chamber, only the back plate needs to be simply detached from the frequency converter to expose the heat dissipation chamber and the heat sink for cleaning, without the need to detach the heat sink, electrical and electronic elements or other structures of the frequency converter, and the cleaning process is very simple and avoids damage to the frequency converter and its elements caused by detaching many elements of the frequency converter. BRIEF DESCRIPTION OF DRAWINGS

[0017] The features and advantages of the present application will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings provided only by way of illustration, wherein:

[0018] Figure 1 is a perspective view of a frequency converter according to an embodiment of the present application.

[0019] Figure 2 is Figure 1 a perspective view of the frequency converter shown in Fig. 1 without the back plate.

[0020] Figure 3 is Figure 1 an exploded view of the frequency converter shown in Fig. 1.

[0021] Figure 4 is Figure 1 a rear view of the frequency converter shown in Fig. 1.

[0022] Figure 5 is Figure 4 a sectional view taken along line A-A of the frequency converter shown in Fig. 1.

[0023] Figure 6 is Figure 4 a sectional view taken along line B-B of the frequency converter shown in Fig. 1.

[0024] Figure 7 is Figure 4 a sectional view taken along line A-A of the frequency converter shown in Fig. 1 using a back plate according to another embodiment.

[0025] BRIEF DESCRIPTION OF DRAWINGS

[0026] 1. housing assembly; 11. heat dissipation chamber; 101. housing portion; 111. peripheral wall; 12. component chamber; 102. cover portion; 13. back plate; 131. first recess; 132. second recess; 133. reinforcing rib; 14. side plate / long wall; 15. air inlet cover plate / short wall; 16. air outlet cover plate / short wall; 17. aperture; 18. aperture; 2. mounting plate; 3. heat sink; 4. electrical and electronic components; 5. fan; 6. capacitor; 7. snap structure. DETAILED DESCRIPTION

[0027] Embodiments of the present application will be described below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one skilled in the art that the present application can be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order not to unnecessarily obscure the present application. In addition, it is to be understood that the present application is not limited in its application to the particular embodiments described below. Instead, the application is capable of achieving its objects by various combinations of the features and elements set forth below using any of the various means possible within the scope of the application. Accordingly, the following aspects, features, embodiments and advantages are merely illustrative and are not required.

[0028] In the following description, terms such as "first", "second", etc. are used to describe various elements, and these terms are only used to distinguish one element from another, and are not used to limit the nature, order or number of the elements. The terms "comprise" and "have" are used to mean open inclusion, and refer to the presence of additional elements / components besides the listed elements / components.

[0029] Figures 1 to 6 A frequency converter according to one embodiment of the present application is shown. As shown, the frequency converter according to this embodiment can mainly comprise a housing assembly 1, a mounting plate 2, a heat sink 3, electrical and electronic components 4, and a fan 5. Figures 1 to 3

[0030] ​The housing assembly 1 defines the overall outer contour of the inverter, and encloses an internal space in which the other components of the inverter, except for the housing assembly 1, are substantially accommodated. The housing assembly 1 can generally be made of a plastic material, so as to be easily formed into a desired shape, and has a relatively light weight and a low cost. The mounting plate 2 is a generally plate-shaped structure installed in the internal space of the housing assembly 1, and can be detachably or integrally connected with the inner wall of the housing assembly 1, and divides the internal space into a heat dissipation chamber 11 and a component chamber 12. Among them, the heat dissipation chamber 11 is located on one side of the mounting plate 2 (the back side or rear side of the inverter), and a heat sink 3 made of, for example, an aluminum alloy material is installed therein. The component chamber 12 is located on the other side of the mounting plate 2 (the front side or front side of the inverter), and at least most of the electrical and electronic components 4 of the inverter are installed therein. In the illustrated embodiment, part of the electronic components carried on the circuit board (see especially Figure 3 ) is shown as an example of the electrical and electronic components 4. The heat sink 3 located in the heat dissipation chamber 11 can be in thermal contact with the electrical and electronic components 4 located in the component chamber 12 via an opening on the mounting plate 2, thereby allowing the heat generated by the electrical and electronic components 4 when operating to be dissipated and conducted out of the inverter via the heat sink 3.

[0031] Corresponding to the heat dissipation chamber 11 and the component chamber 12, the housing assembly 1 can include a housing portion 101 and a cover portion 102. The housing portion 101 substantially encloses one side of the mounting plate 2 (the side on which the heat dissipation chamber 11 is located) to cooperatively define the heat dissipation chamber 11 with the mounting plate 2. The cover portion 102 substantially encloses the other side of the mounting plate 2 (the side on which the component chamber 12 is located) to cooperatively define the component chamber 12 with the mounting plate 2. The cover portion 102 and the housing portion 101 are assembled together, for example, in a detachable manner from each other, to constitute the housing assembly 1 defining the internal space.

[0032] As shown in Figure 2 and 3 , the housing portion 101 can include a back plate 13 and a peripheral wall 111. The back plate 13 is disposed opposite / against the mounting plate 2. The peripheral wall 111 extends around the periphery of the mounting plate 2 to the back plate 13 on the side of the heat dissipation chamber 11, thereby in the form of a ring-shaped frame. In the illustrated embodiment, the peripheral wall 111 is configured as a rectangular frame, including two short walls 15, 16 disposed opposite (the two short walls are vertically opposite in Figure 2 , and two long walls 14 disposed opposite (the two long walls are horizontally opposite in Figure 2(left and right opposite in the middle). The mounting plate 2 can be connected to one or more of the two short walls 15, 16 and the two long walls 14. In the present utility model, the back plate 13 is detachably mounted on the peripheral wall 101 and is separated from the radiator 3 located in the heat dissipation chamber 11. In this article, "separated" means that there is a gap between the back plate 13 and the radiator 3 and there is no contact or connection. Since the back plate 13 is detachably mounted in the inverter and is separated from the radiator, when it is necessary to remove dust from the heat dissipation chamber 11, it is only necessary to simply remove the back plate from the inverter to expose the heat dissipation chamber and the radiator for cleaning, without having to remove the radiator, electrical and electronic components or other structures of the inverter before dust removal. This greatly simplifies the cleaning and dust removal operations of the heat dissipation chamber of the inverter, and can also avoid possible damage to the inverter and its components caused by disassembling the inverter.

[0033] The back plate 13 can be detachably mounted on the peripheral wall 111 by means of the snap-fit ​​structure 7. In one embodiment, with particular reference to Figure 3 As shown, the snap structure 7 may include hooks and holes. The back panel 13 is generally rectangular in shape. Four hooks may be provided at approximately the four corners of the back panel 13 and extend toward the inner side of the back panel (the side facing the heat dissipation chamber 11 when the back panel is installed). Corresponding holes are provided near the ends of the two long walls 14 of the peripheral wall and correspond one-to-one with the four hooks. When the back panel 13 is pressed against the peripheral wall 111, each hook may abut against the inner side of the corresponding long wall 14 and undergo elastic deformation until the hook portion at the end of the hook enters the corresponding hole and rebounds, thereby fixing the back panel 13 to the long wall 14. In other embodiments, the back panel 13 may also be mounted to the peripheral wall 111 by fasteners (such as bolts or latches) or any other suitable detachable means.

[0034] It should be noted that the term "detachable" as used above does not necessarily mean that the back panel can be completely removed from the peripheral wall. Rather, the back panel can be removed from the peripheral wall to a sufficient degree to expose the heat dissipation cavity, allowing for convenient cleaning of the heat dissipation cavity and its internal components (such as the radiator). For example, the back panel can also be hinged to the peripheral wall like a door, but can be fully opened to expose the heat dissipation cavity for easy cleaning.

[0035] like Figure 2 and 3As shown, to facilitate the dissipation of heat generated by the inverter during operation from the radiator 3, a fan 5 facing the radiator 3 may be provided in the heat dissipation chamber 11 for blowing cooling air toward the radiator 3. To form an air duct within the heat dissipation chamber 11 for blowing cooling air through the radiator 3, an air inlet and an air outlet are provided on the peripheral wall 111 surrounding the heat dissipation chamber 11. When operating, the fan 5 draws cooling air from the outside into the heat dissipation chamber 11 through the air inlet and blows it toward the radiator 3. This cooling air then absorbs heat from the radiator 3 and becomes hot air, ultimately leaving the heat dissipation chamber 11 through the air outlet, carrying the heat.

[0036] In the embodiment shown in the figure, the heat sink 3 is arranged so that its multiple parallel fins are arranged along Figure 2 and 3 , and the fan 5 is arranged at the top of the heat dissipation chamber 11, thereby being located above the radiator 3. Accordingly, the air inlet and the air outlet are respectively arranged at the top and the bottom of the heat dissipation chamber 11, thereby forming an air duct from top to bottom in the heat dissipation chamber 11, for cooling air to enter from the air inlet and pass downward through the gaps between the fins of the radiator 3 to absorb heat before leaving through the air outlet. More specifically, the two short walls 15 and 16 of the peripheral wall 111 in the form of a rectangular frame are respectively constructed as an air inlet cover plate 15 and an air outlet cover plate 16, the air inlet cover plate 15 having an aperture 17 used as an air inlet, and the air outlet cover plate 15 having an aperture 18 used as an air outlet. The two long walls 14 of the peripheral wall 111 are composed of two upright side panels connected to the air inlet cover plate 15 and the air outlet cover plate 16. Because the air inlet and outlet are formed in the two short walls (the air inlet cover and the air outlet cover) 15 and 16 of the rectangular frame-shaped peripheral wall 111, respectively, the air inlet and outlet can be aligned with each other, thereby forming a straight-through air duct with a relatively small cross-sectional area (flow area) between the two side panels 14. This allows for a more concentrated, higher-flow, and more intense cooling air to be generated at the same fan speed or power, thereby improving the heat dissipation and cooling effect.

[0037] Optionally, at least one of the two short walls 15, 16 and the two long walls 14 of the peripheral wall 111 is detachably connected to the frequency converter. That is, one or more of the two short walls 15, 16 and the two long walls 14 can be detached from the frequency converter. For example, Figure 3As shown, the air inlet cover plate 15, which is a short wall, can be detachably connected with the two side plates 14 and the mounting plate 2, which are long walls. In this way, when the heat dissipation chamber 11 is to be cleaned, the air inlet cover plate 15 can be detached from its surrounding associated components (e.g. the side plates 14 and the mounting plate 2) to facilitate the cleaning of the fan 5 mounted adjacent to the air inlet cover plate 15. A bracket for mounting the fan 5 can also be connected to the lower portion of the air inlet cover plate 15. In another embodiment, one or both of the side plates 14 can also be detached from its surrounding associated components (e.g. the air inlet cover plate 15 and the air outlet cover plate 16 and the mounting plate 2) to provide access to the heat dissipation chamber 11 from the side of the inverter for cleaning. As an additional or alternative option, the air outlet cover plate 16 can also be detached from its surrounding associated components (e.g. the two side plates 14 and the mounting plate 2). In summary, at least one of the walls (two short walls 15, 16 and at least one of the two long walls 14) of the peripheral wall 111 of the housing portion 101, in addition to the back plate 13, can be configured to be detachable, thereby increasing the access to the heat dissipation chamber 11 for facilitating a more flexible and thorough cleaning of the heat dissipation chamber 11. It should be noted that the "detachable" of the at least one wall referred to herein does not mean that the wall must be capable of being completely removed and taken off from the inverter, but only that the wall is detachable to a degree that provides sufficient access to the heat dissipation chamber and its internal components for facilitating the cleaning thereof.

[0038] Figures 5 to 6 A cross-sectional view of the inverter according to the present embodiment taken along the A-A line and the B-B line as shown in Figure 4 Figure 5 As shown, the heat sink 3 fixed on the mounting plate 2 extends towards the back plate 13 and is spaced apart from the back plate 13. The inverter according to the present embodiment has a relatively high power and generates a relatively large amount of heat, and the size of the heat sink 3 is also relatively large to ensure the heat dissipation effect. Therefore, the heat sink 3 extends towards the back plate 13 and is spaced apart from the inner side of the back plate 13 by only a small gap. However, inverter products of the same series can have different power segments, and a lower power inverter generates a smaller amount of heat. Correspondingly, a smaller heat sink is often used to reduce the weight and cost of the heat sink while maintaining sufficient heat dissipation effect. For example, similar to Figure 5 Figure 7 A cross-sectional view of an inverter according to another embodiment is shown, in which the size of the heat sink 3 is relatively small, and thus a large gap exists between the heat sink 3 and the back plate 13. In this case, a portion of the cooling air blown by the fan 5 towards the heat sink 3 flows away from the gap around the heat sink 3 and cannot be used to carry away heat from the heat sink 3, thereby causing a loss of heat dissipation and cooling effect. For this reason, in Figure 7 ​​In the embodiment shown, a first recess 131 is provided on the back plate 13, which recesses towards the heat dissipation chamber 11 facing the heat sink 3, so that the gap between the back plate 13 and the heat sink 3 is reduced at the recessed position. In this way, the cooling air flowing from the gap around the heat sink 3 can be reduced, so that as much cooling air as possible passes between the fins of the heat sink 3 to carry away more heat, improving the heat dissipation effect. In addition, for frequency converters with different powers, by replacing only the back plate 13 with a first recess 131 of different depth to match the different sizes of the heat sink of these frequency converters, the heat dissipation effect of frequency converters with different powers can be optimized at a lower cost.

[0039] The frequency converter according to one embodiment of the present application can further include a heat generating device connected to the circuit board but extending into the heat dissipation chamber 11 through a corresponding hole provided on the mounting plate 2 from the element chamber 12, such as, for example, Figure 2 and 3 the plurality of capacitors 6 shown. The heat generating device such as the capacitor 6 can be arranged in the air duct in the heat dissipation chamber in parallel with the heat sink in a direction (left-right direction in Figure 2 ) transverse to the direction of the cooling air. As can be seen from Figure 6 , there is also a large gap between the end of each capacitor 6 and the back plate 13. Therefore, when the cooling air blows downward from the air inlet cover plate 15 to the air outlet cover plate 16 as shown in Figure 2 , part of the cooling air will be diverted from the heat sink 3 into the gap between the capacitors 6 and the back plate 13 to flow downward around the heat sink 3 and the capacitors 6, so that the cooling air carries away less heat from the heat sink 3 and the capacitors 6, reducing the heat dissipation effect.

[0040] To this end, as shown in Figure 3 , 4 and 6, one or more second recesses 132 can also be provided on the back plate 13, which recesses towards the heat dissipation chamber 11 facing the plurality of capacitors 6, so that the gap between the back plate 13 and the plurality of capacitors 6 is reduced at the recessed position. Figure 6 Four capacitors 6 are exemplified in , which are arranged in the up-down direction and have the same size (height), in which case the second recess 132 can be a long slot as shown. When, for example, adjacent capacitors 6 are far apart, a corresponding second recess 132 can be provided for each capacitor 6 or for each group of capacitors 6. By providing the second recess 132, the gap between the capacitors 6 and the back plate 13 can be reduced, thereby reducing the cooling air diverted from the heat sink 3 into the gap, so that as much cooling air as possible passes between the fins of the heat sink 3 or between the heat sink 3 and the capacitors 6 to carry away more heat, improving the heat dissipation effect.

[0041] Continuing to refer to Figure 6As shown, at least one second groove 132 can be provided with a reinforcing rib 133. Figure 4 As shown, in the long strip-shaped second groove 132, for example, three reinforcing ribs 133 are arranged in parallel along the length direction of the second groove 132 and all extend along the width direction of the second groove 132. The reinforcing ribs 133 can increase the strength of the back plate 13 at the second groove 132, and in addition, the reinforcing ribs 133 can also be used as a handle to facilitate the grasping of the back plate 13 when the back plate 13 is detached from the peripheral wall 111.

[0042] For different frequency converters installed with capacitors of different heights (for example, capacitors from different manufacturers), by only replacing the back plate 13 with a second groove 132 of different depth to match these capacitors of different heights, the heat dissipation effect of these different frequency converters can be optimized at a lower cost.

[0043] It should be noted that the above-mentioned heat generating devices are not limited to capacitors 6, and in some types of frequency converters, other heat generating devices such as inductors and the like can also exist, which extend from the element chamber 12 through the mounting plate 2 to the heat dissipation chamber 11. For these heat generating devices, a second groove with a depth matching the height dimension of the heat generating device extending to one side of the heat dissipation chamber can also be provided on the back plate 13 to reduce the gap between the heat generating device and the back plate, thereby improving the heat dissipation effect.

[0044] Various modifications and variations to the disclosed embodiments can be made without departing from the scope or spirit of the present application. Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given should be considered exemplary only, and the true scope of the application is indicated by the appended claims, along with the full range of equivalents to which such claims are entitled.

Claims

1. A frequency converter, comprising a housing assembly (1) and a mounting plate (2), wherein the mounting plate is connected to the inner wall of the housing assembly to divide the interior space of the housing assembly into a heat dissipation chamber (11) and a component chamber (12) located on both sides of the mounting plate, wherein a heat sink (3) of the frequency converter is installed in the heat dissipation chamber, and an electrical and electronic component (4) of the frequency converter is installed in the component chamber, wherein the frequency converter is characterized in that: The housing assembly (1) comprises a housing portion (101) which defines the heat dissipation chamber (11) together with the mounting plate (2); the housing portion comprises a back plate (13) arranged opposite to the mounting plate and a peripheral wall (111) extending from the peripheral edge of the mounting plate (2) to one side of the heat dissipation chamber (11) of the back plate; the back plate is detachably mounted on the peripheral wall and is separated from the radiator (3).

2. The frequency converter according to claim 1, characterized in that: The heat dissipation chamber (11) is further provided with a fan (5) facing the radiator (3), and the peripheral wall (111) is provided with an air inlet and an air outlet, so that an air duct is formed in the heat dissipation chamber, extending from the air inlet via the fan to the air outlet to blow cooling air through the radiator (3).

3. The frequency converter according to claim 2, characterized in that: The peripheral wall (111) is in the form of a rectangular frame comprising two oppositely arranged short walls and two oppositely arranged long walls (14), wherein the two short walls are respectively composed of an air inlet cover plate (15) with an opening serving as the air inlet and an air outlet cover plate (16) with an opening serving as the air outlet.

4. The frequency converter according to claim 3, characterized in that: At least one of the two short walls and the two long walls of the peripheral wall (111) is detachably connected to the frequency converter.

5. The frequency converter according to any one of claims 2 to 4, characterized in that: The back plate (13) is provided with a first groove (131) facing the heat sink (3) and recessed toward the heat sink chamber (11) so that the gap between the back plate and the heat sink is reduced at the recessed portion.

6. The frequency converter according to any one of claims 2 to 4, characterized in that: The frequency converter comprises a heating device extending from the component chamber (12) through the mounting plate (2) toward the back plate (13) into the heat dissipation chamber (11); the heating device and the radiator (3) are arranged side by side in the air duct in a direction transverse to the cooling wind.

7. The frequency converter according to claim 6, characterized in that: The back plate (13) is provided with one or more second grooves (132) facing the heating device and recessed toward the heat dissipation chamber (11) so that the gap between the back plate and the heating device is reduced at the recessed portion.

8. The frequency converter according to claim 7, characterized in that: A reinforcing rib (133) is provided in at least one of the second grooves (132).

9. The frequency converter according to claim 7, characterized in that: The heating device includes a plurality of capacitors (6).

10. The frequency converter according to any one of claims 1 to 4, characterized in that: The back plate (13) is detachably mounted on the peripheral wall (111) via a snap-fit ​​structure (7) or a fastener.

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