CN204257409U - The capacitance component of frequency converter and frequency converter - Google Patents

Abstract

A capacitor component of a frequency converter, including a plurality of electrolytic capacitors fixedly installed on a capacitor mounting board, every two electrolytic capacitors are connected in series through a capacitor connection copper bar to form a capacitor group, and a plurality of capacitor groups are arranged on the capacitor mounting board, A plurality of capacitor groups are connected in parallel through the capacitor negative mother copper bar and the capacitor positive mother copper bar arranged in layers; an intermediate insulating board is arranged between the capacitor negative mother copper bar and the capacitor positive mother copper bar. The capacitor component of the utility model has compact structure and convenient assembly, and can effectively reduce the stray inductance of the circuit. Moreover, the capacitor components are arranged in a composite manner, which effectively reduces the volume of the capacitor components. The utility model also provides a frequency converter with reasonable parts, good heat dissipation effect and low cost.

Description

Capacitive components of frequency converters and frequency converters

technical field

The utility model belongs to the field of low-voltage electrical appliances and relates to a frequency converter and a capacitor component of the frequency converter.

Background technique

The birth of frequency converter stems from the demand for stepless speed regulation of AC motors. With the emergence of components such as thyristors, electrostatic induction transistors, and high-voltage insulated gate bipolar thyristors, electrical technology has changed rapidly, and speed regulation technology of frequency converters has also changed. With the development, the special pulse width modulation variable voltage variable frequency speed regulation technology has made the frequency converter reach a new level.

However, with the continuous extension of the application field of power electronics technology, frequency converters have gradually penetrated into various fields of industry. Therefore, the market has more and more requirements for the performance and power of frequency converters, and high-power frequency converters have also been born. ; High-power inverters have higher requirements on the layout of the structure than those of low-power inverters, because the capacity, quantity, and heat dissipation requirements of devices are relatively high. An unreasonable layout will lead to poor heat dissipation, large volume and high cost of the entire device. Moreover, many existing frequency converter power devices use high-power tubes as much as possible, which leads to excessive dependence on the device and increases the design cost; the heat dissipation method is to uniformly install the devices on a radiator, which leads to single-block heat dissipation. The device is large in size and heavy in weight, and the heavy weight also requires high assembly requirements, which brings great inconvenience to production and installation. Sometimes two or more assembly personnel are required to install it, and the heat dissipation effect is not very good.

Moreover, the existing frequency converter has many components, the assembly process is complicated, the production line has too many stations, and the assembly efficiency is not high. For example, the electrolytic capacitor used in the inverter has a low withstand voltage level, and multiple capacitors need to be connected in parallel to match the rated capacity, resulting in a large number of capacitors. The single installation method on the whole machine makes the installation of the whole machine time-consuming, and the design needs to consider the assembly The number of problems increases, which increases the cost of design and assembly; moreover, the positive and negative connections of the existing inverter capacitors are simply lapped with copper bars, which makes the stray inductance in the circuit too large, requiring a lot of power on the capacitor module. Only a large-capacity absorbing capacitor can ensure the safety of the module, which increases the cost of the capacitor and shortens the life of the capacitor module.

Moreover, on the one hand, the frequency converter needs to minimize the volume, on the other hand, there are many components, and it needs to ensure the current carrying between the electrical connections, so that the electrical gap between the terminals of some components has certain hidden dangers in practical applications. For example, take the terminal of the IGBT tube as an example, the distance between the PN terminals is very close. Due to the requirements of the carrying capacity of the copper bar, the distance between the copper bar and the copper bar is too close, and there is a safety hazard. In order to eliminate this hidden danger, the copper bar is generally used The fixing hole is eccentric, which makes the processing of the copper row difficult, and the actual effect is not good.

Contents of the invention

The purpose of the utility model is to overcome the defects of the prior art, and provide a capacitor component of a frequency converter with small stray inductance, compact structure and convenient assembly, and a frequency converter with reasonable parts, good heat dissipation effect and low cost.

In order to achieve the above object, the utility model adopts the following technical solutions:

A capacitor component of a frequency converter, including a plurality of electrolytic capacitors 803 fixedly installed on a capacitor mounting plate 804, every two electrolytic capacitors 803 are connected in series through a capacitor connection copper bar 805 to form a capacitor group, and the capacitor mounting plate 804 is provided with A plurality of capacitor groups are connected in parallel through the capacitor negative mother copper bar 802 and the capacitor positive mother copper bar 801 arranged by stacking; an intermediate layer insulation is provided between the capacitor negative mother copper bar 802 and the capacitor positive mother copper bar 801 Board 807.

Further, the capacitor assembly 8 includes nine groups of capacitor groups composed of 18 electrolytic capacitors 803, and the electrolytic capacitors 803 of the nine groups of capacitor groups form an array of 6 by 3, wherein six groups of capacitor groups are arranged side by side to form an array of 6 by 2, The six electrolytic capacitors 803 of the other three sets of capacitors are arranged in sequence to form a 6 by 1 array, and jointly form a 6 by 3 array.

Further, every two electrolytic capacitors 803 are connected in series through a bar-shaped capacitor connection copper bar 805 to form a capacitor group; the capacitor negative electrode mother copper bar 802 and the capacitor positive electrode mother copper bar 801 hollow out the position of the capacitor connection copper bar 805 and ensure electrical The gap and creepage distance are superimposed on the electrolytic capacitor 803, the capacitor negative pole mother copper bar 802 connects the negative pole of the capacitor group, and the capacitor positive pole mother copper bar 801 connects the positive pole of the capacitor group to realize the parallel connection of the capacitor group; A middle insulating plate 807 is provided between the row 802 and the positive capacitor copper bar 801 , and an upper insulating plate 806 is provided on the positive capacitor copper bar 801 .

The utility model also provides a frequency converter, including the capacitor assembly of the frequency converter.

Further, the frequency converter is installed vertically on the ground and wall, including a base 9, an exhaust-type cooling fan 1 is installed in one end of the base 9, an air inlet is provided on the side wall of the other end, and the radiator is arranged close to the cooling fan 1 In the base 9; the IGBT module 6 and the rectifier module 3 are installed on the same side of the radiator, the rectifier module 3 is arranged on the radiator near the end of the cooling fan 1, and the IGBT module 6 is arranged on the radiator near the air inlet On one end; the end of the base 9 where the heat dissipation fan 1 is installed is provided with an incoming and outgoing line terminal 2, and the other end is provided with a bracket 904, and a capacitor assembly 8 is installed in the bracket 904.

Further, one side of the negative capacitor bus bar 801 and the positive capacitor bus bar 802 of the capacitor assembly are respectively provided with a negative connecting copper bar 8021 and a positive connecting copper bar 8022 connected to the IGBT module 6, and a negative connecting copper bar 8021 and a positive connecting copper bar are provided. The row 8022 is provided with a plurality of connection holes connected to the connection terminals of the IGBT tubes of the IGBT module 6 .

Further, the radiator includes a first radiator 4 and a second radiator 5 arranged side by side in the base 9, the length of the first radiator 4 and the second radiator 5 are the same, and the width of the first radiator 4 is smaller than that of the first radiator 4. Two radiators 5.

Further, the rectification module 3 includes three groups of diode single-phase modules, and each group of diode single-phase modules includes a plurality of diodes connected in parallel.

Further, the IGBT module 6 includes three groups of IGBT single-phase modules, and each group of IGBT single-phase modules includes a plurality of parallel-connected IGBT tubes.

The capacitor assembly of the utility model is compact in structure, easy to assemble, and can effectively reduce the stray inductance of the circuit. The capacitor and resistor are first assembled into a whole and then installed on the frequency converter. The assembly is convenient, and the installation speed of the whole machine is effectively shortened. Moreover, the capacitor components are arranged in a composite manner, which effectively reduces the volume of the capacitor components. The layout of the frequency converter of the utility model is reasonable, and the heat dissipation performance is optimized. The modules are connected in parallel to reduce the cost and reduce the dependence on the module specifications. The radiator is divided into multiple pieces, which reduces the volume of a single radiator, shortens the heat dissipation path, improves assembly efficiency, and reduces labor costs.

Description of drawings

Fig. 1 is a schematic diagram of the wind flow direction of the frequency converter of the present invention;

Fig. 2 is the structural diagram of the frequency converter of the present invention;

Fig. 3 is the assembly diagram of the frequency converter of the present utility model;

Fig. 4 is the structural diagram of the capacitor assembly of the present utility model;

Fig. 5 is an exploded view of the capacitor assembly of the present invention;

Fig. 6 is a schematic diagram of the mounting plate at the bottom of the capacitor assembly of the present invention;

Fig. 7 is a schematic diagram of the top of the capacitor assembly of the present invention;

Fig. 8 is the layout and connection circuit diagram of the electrolytic capacitor of the capacitor assembly of the present invention;

Fig. 9 is an assembly structure diagram of the IGBT tube and the isolation rubber pad of the utility model;

Fig. 10 is an exploded view of the utility model IGBT tube and the isolation rubber pad;

Fig. 11 is a structural diagram of the bottom of the IGBT tube of the present invention;

Fig. 12 is a structural diagram of the isolation rubber pad of the utility model.

Detailed ways

The specific implementation of the frequency converter of the present invention will be further described below with reference to the embodiments given in accompanying drawings 1 to 12 . The frequency converter of the present invention is not limited to the description of the following embodiments.

As shown in Figure 1-3, the frequency converter includes a base 9, and an air-drawing cooling fan 1 is installed in one end of the base 9, and the radiator is arranged in the base 9 close to the cooling fan 1, and the radiator includes first Radiator 4 and second radiator 5; IGBT module 6 and rectifier module 3 are installed on the same side of the radiator, rectifier module 3 is arranged on the radiator near one end of cooling fan 1, and IGBT module 6 is arranged on the heat dissipation The rectifier module 3 is closer to the heat dissipation fan 1 than the IGBT module 6 on the end close to the air inlet, and the heat sink is also equipped with a temperature relay 7; the end of the base 9 installed with the heat dissipation fan 1 is provided with an incoming and outgoing line terminal 2, and the other end Capacitive components 8 are also provided on it.

The base 9 includes a base 901, one end of the base 901 is equipped with a heat dissipation fan 1 on the side wall opening, and the other end side wall is provided with a plurality of air inlets, and an air duct that is easy to dissipate heat is formed in the base 901; the top of the base 901 is open , the first radiator 4 and the second radiator 5 are arranged side by side in the air duct of the base near one end of the cooling fan 1, the first radiator 4 and the second radiator 5 are connected by a connecting piece 903, and the top of the base 901 is close to One end of the air inlet is provided with a cover plate 902, the cover plate 902 presses one end of the radiator, the base 901, the cover plate 902 and the connecting piece 903 are fixedly connected to fix the radiator in the base 9; The bracket 904 of the component 8, the capacitor component 8 is installed in the bracket 904.

The frequency converter of the present utility model adopts the mode of vertical ground wall-mounted installation, and the air flow direction is from bottom to top (as shown in Figure 1), and described heat dissipation blower 1 is installed on the upper end of base 9, is positioned at the top of radiator, adopts air-drawing This method ensures smooth air circulation and effectively reduces wind resistance and noise in the radiator air duct. The incoming and outgoing wire terminals 2 are arranged on the upper end of the base 9 at the position corresponding to the heat dissipation fan 1, and the incoming and outgoing wires are designed as top-in and top-out, which is convenient for users to enter and exit on-site.

The rectification module 3 includes three groups of diode single-phase modules, and each group of diode single-phase modules includes 6 parallel-connected diodes. The rectification module 3 adopts the parallel connection of 6 diodes, which can effectively reduce the cost. The rectification module 3 is installed on the radiator near the air outlet and the inlet and outlet terminals 2, and the rectification module 3 is arranged on the radiator near one end of the heat dissipation fan 1. The IGBT module 6 is set on the end of the radiator close to the air inlet, and the rectifier module 3 is closer to the cooling fan 1 than the IGBT module 6, which can shorten the distance of the incoming line, and at the same time, the heating value of the diode is much smaller than that of the IGBT, which is beneficial to the radiator. The heat flow direction installed vertically on the ground satisfies the principle of heat conduction from high to low, which is conducive to accelerating heat dissipation.

The IGBT module 6 includes three groups of IGBT single-phase modules, and each group of IGBT single-phase modules includes three parallel-connected IGBT tubes (insulated gate bipolar transistors). The IGBT module 6 adopts three IGBT tubes connected in parallel as the one-phase output of the inverter side, which can effectively reduce the device cost, and can replace the heat dissipation of one module by the heat dissipation of multiple small modules, and evenly dissipate the heat dissipation of the module; the IGBT module It is fixed at the air inlet and close to the inverter side; the main core component of the inverter is on the inverter side, so try to ensure the shortest path of the inverter circuit to reduce the stray inductance of the input side of the inverter tube, thereby reducing the IGBT In the dv/dt of turn-on and turn-off, the service life of the IGBT is extended and the equipment loss is reduced.

Described radiator comprises the first radiator 4 and the second radiator 5 that are arranged side by side in the base 9, the length of the first radiator 4 and the second radiator 5 are identical, the width of the first radiator 4 is smaller than the second radiator. The radiator 5; the first radiator 4 and the second radiator are arranged side by side in the same air duct of the base 9. The width of the first radiator 4 is about 1/2 of the second radiator 5, a group of diode single-phase modules and a group of IGBT single-phase modules are arranged on the first radiator 4, two groups of diode single-phase modules and two The group IGBT single-phase module is arranged on the second radiator 5; the diode single-phase module and the IGBT single-phase module are arranged on the side of the first radiator 4 and the second radiator 5 in the same direction. Of course, the radiators can also be three pieces arranged side by side, or more. The first radiator 4 and the second radiator 5 are arranged side by side in the same air duct, and are fixed in the base 9 with screws. Making the radiators two or more can not only reduce the weight and volume of a single radiator, Moreover, the processing is simple, the installation is flexible, and the heat dissipation path is shortened, which can not only avoid the problem of inconvenient installation for a worker caused by an oversized and heavy radiator, but also ensure that the heat dissipation performance of the radiator is more perfect.

The temperature relay 7 is mainly used for temperature detection on the surface of the radiator, and a plurality of temperature relays 7 are arranged on the radiator in an array to detect the temperature of each point of the radiator. The capacitor assembly 8 is installed in the bracket 904 of the base 9, placed at the lower end of the inverter side and close to the upper end of the radiator, so that the capacitor and the module are basically on the same level. This arrangement can reduce the frequency converter The overall height of the radiator saves the material cost of the radiator.

The structure of the frequency converter of the utility model is reasonable, and the heat dissipation performance is optimized; the rectifier diode and the IGBT module are connected in parallel with multiple devices, which reduces the dependence on the module specification, saves costs, and avoids being limited by electrical appliances due to excessive current The problem of no source of supply caused by components, and at the same time, it can avoid the problem of poor heat dissipation of the inverter caused by the poor heat dissipation of a single device; the radiator is divided into multiple pieces, and the heat dissipation is separated, which reduces the volume of a single radiator and shortens the heat dissipation path. The assembly efficiency is improved, the labor cost is reduced, and it is especially suitable for the installation of high-power frequency converters.

The assembly process of the frequency converter of the utility model is simple and convenient, and the assembly of the whole machine can be completed by one assembly person; when assembling, first push the two radiators 4 and 5 into the base from the air inlet, and screw the two radiators The radiators are respectively locked on the base; after the rectifier module 3, the IGBT module 6 and the temperature relay 7 are coated with thermal silica gel, they are respectively fixed on the radiators with screws. The above three modules can be installed in any order, but the installation Attention must be paid to the direction; then the assembled capacitor assembly 8 is directly mounted on the bracket 904 .

As shown in Figures 4-8, the capacitor assembly 8 includes a plurality of electrolytic capacitors 803 installed on a capacitor mounting plate 804; every two electrolytic capacitors 803 are connected in series through a capacitor connection copper bar 805 to form a capacitor group, and the capacitor mounting plate 804 is provided with a plurality of capacitor groups, and the capacitor negative mother copper bar 801 and the capacitor positive electrode mother copper bar 802 are connected in parallel between the multiple capacitor groups; A middle insulating plate 807 is provided, and an upper insulating plate 806 is provided on the capacitor positive mother copper bar 802 . The capacitor assembly 8 includes 18 electrolytic capacitors 803, the 18 electrolytic capacitors 803 are arranged in an array and fixedly installed on the capacitor mounting board 804, and the 18 electrolytic capacitors 803 are connected in series with copper bars 805 through 9 capacitors to form nine capacitors. Group capacitor group; on the array composed of electrolytic capacitors 803, capacitor negative electrode mother copper bars 801 and capacitor positive electrode mother copper bars 802 are stacked in sequence; capacitor negative electrode mother copper bars 801 and capacitor positive electrode mother copper bars 802 are hollowed out capacitor connection copper bars 805 position and ensure the electrical clearance and creepage distance, the capacitor negative busbar 801 connects the negative pole of the capacitor group, and the capacitor positive busbar 802 connects the positive pole of the capacitor group to realize the parallel connection of nine groups of capacitor groups; A middle insulating plate 807 is provided between the copper bar 801 and the capacitor positive mother copper bar 802 , and an upper insulating plate 806 is provided on the capacitor positive mother copper bar 802 . On one side of the capacitor negative bus bar 801 and the capacitor positive bus bar 802, there are respectively a negative connecting piece 8011 and a positive connecting piece 8021, and on the other side, a negative connecting copper bar 8021 and a positive connecting copper bar connected to the IGBT module 6 are respectively provided. The row 8022 , the negative connection copper row 8021 and the positive connection copper row 8022 are provided with a plurality of connection holes connected to the terminals of the IGBT tube of the IGBT module 6 .

If the nine groups of capacitor groups are arranged in a straight line or vertically, the capacitor assembly 8 will take up too much space in a certain direction, so the capacitor assembly 8 of the present invention adopts a composite arrangement to ensure the occupied space of the capacitor minimum. The electrolytic capacitors 803 of the nine capacitor groups form a 6 by 3 array, and the six capacitor groups are arranged side by side to form a 6 by 2 array, and the 6 electrolytic capacitors 803 of the other three capacitor groups are arranged in a word order to form a 6 by 1 array. Together they form a 6 by 3 array. The schematic diagram of the array and electrical connection of nine groups of electrolytic capacitors is shown in Figure 8. The six groups of capacitor groups are arranged in the order of the positive pole on the top and the negative pole on the bottom.

The main assembly process of the capacitor assembly 8 of the present utility model is as follows: first, 18 electrolytic capacitors 803 are installed on the capacitor mounting plate 804 according to the array shown in Fig. The group capacitors are arranged according to the positive pole on the left and the negative pole on the right; when installing, use screws to slightly tighten the capacitor mounting plate 804 to ensure that the capacitor does not fall off, and then adjust the direction of the capacitor according to the positive and negative poles shown in 8, and it cannot be locked too much Tight, easy to adjust when installing copper bars later. Use capacitor connection copper bar 805 to connect electrolytic capacitors in pairs, pay attention to the positive and negative directions of the capacitors. Install capacitor negative busbar 801, middle insulation board 807, capacitor positive busbar 802 and upper insulation board 806 in sequence, use capacitor lock nut 808 to fix the insulation board and busbar on the capacitor, and finally fasten the electrolysis on the capacitor installation board. Capacitor fixing bolts complete the component installation. A lower insulating plate (not shown in the figure) may also be provided between the capacitor negative busbar 801 and the capacitor terminals to ensure the safety of electrical performance between the capacitor positive and negative busbars and the capacitor shell.

In the capacitor assembly of the utility model, the positive and negative pole copper bars are made into two laminated mother copper bars, and the position of the capacitor connection bar is hollowed out to ensure the electrical clearance and creepage distance, and the middle is separated by insulating materials to ensure the electrical performance requirements ; Not only improves the assembly efficiency, but also can effectively reduce the stray inductance of the circuit. If the positive and negative copper bars on the electrolytic capacitor array are overlapped according to the simple circuit method similar to the capacitor connection copper bar 805, the stray inductance Ls of the bus bar will be very large, thereby increasing the IGBT module. The dv/dt of the module is easy to be damaged. In this embodiment, the capacitor assembly adopts two large copper bars. The capacitor positive electrode mother copper bar 802 and the capacitor negative electrode mother copper bar 801 are laminated, and the middle is separated by an insulating material. Connect the electrolytic capacitor according to the method shown in Figure 7. Positive and negative poles, the distributed capacitance formed by stacked positive and negative pole copper bars can offset the stray inductance between the copper bars and prolong the service life of the IGBT module. The positive and negative poles of the distributed capacitance are determined according to the rectified polarity of the front end of the frequency converter, so in this embodiment, the side away from the capacitor terminal is the positive pole, and the side close to the terminal is the negative pole.

The capacitor assembly of the utility model is compact in structure, easy to assemble, and can effectively reduce the stray inductance of the circuit. The capacitor and resistor are first assembled into a whole and then installed on the frequency converter. The whole process of installation can be installed on a fixed installation platform. , It is convenient for assembly personnel to install and fix, effectively reducing the installation speed of the whole machine.

The IGBT module 6 includes three groups of IGBT single-phase modules, each group of IGBT single-phase modules uses three IGBT tubes (insulated gate bipolar transistors) connected in parallel as one-phase output on the inverter side, and the IGBT tubes are arranged on the radiator. The two ends of the IGBT tube 601 are provided with a terminal 603 for wiring. The terminal 603 of the IGBT module can be fixedly connected with the copper bar of the capacitor component through screws. There is a guaranteed electrical clearance between the two terminals 603 at one end of the IGBT tube 601. The isolation rubber pad 602 can also isolate the connection terminal of the IGBT tube and the fixing surface of the radiator. As shown in Figure 11, the bottom of the terminal of the IGBT tube is wrapped in plastic. If the screw for installing the copper bar is too long, the bottom will be damaged, resulting in discharge phenomenon caused by the screw and the fixing surface of the IGBT tube being too close; in addition, to ensure the system The current carrying capacity and the normal processing of the copper bar are not affected, and the copper bar needs to be made relatively wide, so that the distance between the P pole terminal and the N pole terminal of the IGBT tube is too short and less than 8mm. If there is any Conductive foreign matter attached to the two-level copper bar will directly make the two-level conduction and short circuit; therefore, in order to prevent the production staff from damaging the module by taking the screw by mistake, and prevent the electrical gap between the P pole terminal and the N pole terminal If it is too short or a foreign object, an isolation rubber spacer 602 is provided between the P pole terminal and the N pole terminal of the IGBT tube.

As shown in Figures 9-12, an isolation rubber pad 602 is provided between the P pole terminal and the N pole terminal at one end of the IGBT tube 601. The two connecting terminals correspond to the two terminal slots 6021, the interval 6023 between the two terminal slots 6021 corresponds to the gap 6033 between the two connecting terminals, and the interval 6023 between the two terminal slots 6021 is provided with convex The raised spacer beam 6022.

As shown in Figure 11, the bottom and side openings of the connecting terminal 603 form a protective groove 6034, a protective pad 6031 is provided in the protective groove 6034, and a stepped surface 6035 is provided on both sides of the top of the connecting terminal 603; as shown in Figure 12, the The terminal groove 6021 of the isolation rubber pad 602 is also provided with a first boss 6024 corresponding to the protective groove 6034. The first boss 6024 is provided with an inner groove 6025 corresponding to the protective pad 6031. The first boss The side wall groove 6026 for fixing the side wall of the terminal 603 is formed between the 6024 and the side wall of the terminal groove 6021, and the two sides of the top of the terminal groove 6021 extend into the terminal groove 6021 to form a pressing plate that is fixed with the stepped surface 6035 on both sides of the top of the terminal 603 Face 6027.

During installation, the IGBT tube is fixed on the radiator with screws and locked; after that, the isolation rubber pad 602 can be directly inserted into the connection terminal from the side. The P pole terminal and N pole terminal of the IGBT are wrapped in the terminal groove 6021, and the protective pad 6031 is wrapped in the inner groove 6025, which completely isolates the IGBT terminal and the fixed surface of the radiator, and the spacer beam 6022 isolates the two terminals Between; the side wall groove 6026 and the pressure plate surface 6027 of the isolation rubber pad 602 are fixed with the side wall and the step surface 6035 of the terminal 603; it can effectively ensure the electrical clearance, prevent foreign objects from misconducting, and improve the reliability of the inverter. Moreover, the structure is simple, and the installation aspect is beautiful and practical.

The above content is a further detailed description of the utility model in combination with specific preferred embodiments, and it cannot be assumed that the specific implementation of the utility model is only limited to these descriptions. For a person of ordinary skill in the technical field to which the utility model belongs, without departing from the concept of the utility model, some simple deduction or substitutions can also be made, which should be regarded as belonging to the protection scope of the utility model.

Claims (9)

1. A capacitor assembly of a frequency converter, comprising a plurality of electrolytic capacitors (803) fixedly installed on a capacitor mounting plate (804), characterized in that: every two electrolytic capacitors (803) are connected to copper bars (805) through capacitors A capacitor group is connected in series, and a plurality of capacitor groups are arranged on the capacitor mounting plate (804), and the capacitor negative busbar (802) and the capacitor positive busbar (801) arranged in parallel are connected in parallel between the capacitor groups ; An intermediate insulation board (807) is provided between the negative capacitor copper bar (802) and the positive capacitor copper bar (801). 2. The capacitive assembly of the frequency converter according to claim 1, is characterized in that: described capacitive assembly (8) comprises nine groups of capacitance groups that 18 electrolytic capacitors (803) form, the electrolytic capacitor of nine groups of capacitance groups ( 803) form a 6 by 3 array, wherein six groups of capacitors are arranged side by side to form a 6 by 2 array, and the 6 electrolytic capacitors (803) of the other three groups of capacitors are arranged word by word to form a 6 by 1 array, which together form a 6 by 1 array. An array of 3. 3. The capacitor assembly of the frequency converter according to claim 1, characterized in that: every two electrolytic capacitors (803) are connected in series to form a capacitor group through a bar-shaped capacitor connection copper bar (805); row (802) and the capacitor positive female copper row (801) hollow out the position of the capacitor connection copper row (805) and ensure that the electrical clearance and creepage distance are superimposed on the electrolytic capacitor (803), and the capacitor negative female copper row (802) Connect the negative electrode of the capacitor group, and the capacitor positive electrode copper bar (801) connects the positive electrode of the capacitor group to realize the parallel connection of the capacitor group; there is a middle layer between the capacitor negative electrode mother copper bar (802) and the capacitor positive electrode copper bar (801) The insulating plate (807) is provided with an upper layer insulating plate (806) on the positive capacitor copper bar (801). 4. A frequency converter, characterized in that it comprises the capacitor assembly of the frequency converter according to any one of claims 1-3. 5. The frequency converter according to claim 4, characterized in that: said frequency converter adopts the mode of vertical wall-mounted installation on the ground, including a base (9), and an air-drawing cooling fan ( 1), the side wall at the other end is provided with an air inlet, and the radiator is arranged in the base (9) close to the cooling fan (1); an IGBT module (6) and a rectifier module (3) are installed on the same side of the radiator ), the rectifier module (3) is set on the end of the radiator close to the cooling fan (1), the IGBT module (6) is set on the end of the radiator close to the air inlet; the base (9) is equipped with one end of the cooling fan (1) An incoming and outgoing line terminal (2) is provided on the upper end, and a support (904) is provided on the other end, and a capacitor assembly (8) is installed in the support (904). 6. The frequency converter according to claim 5, characterized in that: one side of the capacitor negative mother copper bar (801) and the capacitor positive mother copper bar (802) of the capacitor assembly is respectively provided with a negative electrode connected to the IGBT module (6) Connect the copper bar (8021) and the positive connection copper bar (8022), and the negative connection copper bar (8021) and the positive connection copper bar (8022) are provided with multiple connections connected to the terminals of the IGBT tube of the IGBT module (6) hole. 7. The frequency converter according to claim 5, characterized in that: the radiator includes a first radiator (4) and a second radiator (5) arranged side by side in the base (9), the first radiator (4) and the second radiator (5) have the same length, and the width of the first radiator (4) is smaller than that of the second radiator (5). 8. The frequency converter according to claim 5, characterized in that: the rectification module (3) includes three groups of diode single-phase modules, and each group of diode single-phase modules includes a plurality of diodes connected in parallel. 9. The frequency converter according to claim 5, characterized in that: the IGBT module (6) includes three groups of IGBT single-phase modules, and each group of IGBT single-phase modules includes a plurality of parallel-connected IGBT tubes.