Harmonic current release device for variable frequency motor

Abstract

The utility model relates to the technical field of motor equipment, in particular to a harmonic current release device for a variable frequency motor, which comprises a shell, a fixed ring is slidably connected in the shell, a guide post is fixedly connected in the fixed ring, one end of the guide post is slidably connected with a fixed conductor frame, and the other end of the guide post is fixedly connected with a movable conductor frame. The outer side of the fixed conductor frame is fixedly connected with the shell, the other end of the fixed conductor frame is fixedly connected with a connecting wire, and the other end of the connecting wire is grounded. The carbon brush is in elastic contact with the motor shaft, when the motor rotates, the carbon brush is kept in elastic contact with the extension end of the motor shaft through the spring at the rear end of the carbon brush, shaft current and voltage are released to the ground through the connected connecting wire, the motor shaft is grounded through the carbon brush to form an external circuit, and the shaft voltage on the motor shaft is released through the circuit. Through the application of the device, the safe operation of the motor is effectively ensured, and the device is simple, reliable and convenient to install.

Description

Technical Field

[0001] This utility model relates to the field of motor equipment technology, specifically to a harmonic current release device for a variable frequency motor. Background Technology

[0002] With the gradual popularization of high-voltage variable frequency technology, the importance of variable frequency motors in its application scenarios has become particularly prominent. In field applications, since the variable frequency drive controls the motor through PWM modulation for speed regulation, this results in high-frequency pulse voltages. These pulse voltages generate significant electromagnetic interference, which can cause a discharge effect on the internal structure of the motor bearings, leading to damage to the internal insulation structure. When the variable frequency drive controls the motor, it generates a large amount of harmonic current, which causes harmonic pollution in the bearings. Harmonic pollution causes complex changes in parameters such as the electric field, magnetic field, and temperature inside the bearings, thus affecting bearing performance and leading to premature aging or damage. Therefore, a harmonic current release device for variable frequency motors is proposed to address the above problems. Utility Model Content

[0003] The purpose of this invention is to provide a harmonic current release device for variable frequency motors to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] As an optional embodiment of the harmonic current release device for a variable frequency motor described in this utility model, the device includes a housing, a fixing ring, and a fixing conductor frame.

[0006] The housing has a fixed ring slidably connected inside, and a guide post is fixedly connected inside the fixed ring. One end of the guide post is slidably connected to a fixed conductor frame, and the outer side of the fixed conductor frame is fixedly connected to the housing. The other end of the fixed conductor frame is fixedly connected to a connecting wire, and the other end of the connecting wire is grounded.

[0007] The other end of the guide post is fixedly connected to a mounting base, and the other end of the mounting base is fixedly connected to a carbon brush.

[0008] As an optional solution of the harmonic current release device for variable frequency motors described in this utility model, the outer side of the housing is fixedly connected to a mounting bracket, and the mounting bracket is L-shaped, with evenly distributed threaded holes on the outer side of the mounting bracket.

[0009] As an optional solution of the harmonic current release device for variable frequency motors described in this utility model, a spring is provided on the outer side of the guide column, one end of the spring is fixedly connected to the fixed conductor frame, and the other end of the spring is fixedly connected to a fixing ring.

[0010] As an optional solution of the harmonic current release device for variable frequency motors described in this utility model, the end of the carbon brush facing away from the fixed base is arranged in an arc shape.

[0011] As an optional solution of the harmonic current release device for variable frequency motors described in this utility model, a hollow cylinder is provided at one end of the fixed conductor frame facing the guide post, and the guide post is disposed inside the hollow circular hole and is slidably connected to it.

[0012] Compared with the prior art, the beneficial effects of this utility model are:

[0013] In use, the outer casing of this invention is fixed to the outer side of the bare shaft at the protruding end of the motor shaft by a mounting bracket, and the carbon brushes are in elastic contact with the motor shaft. When the motor rotates, the spring at the rear end of the carbon brushes keeps the carbon brushes in elastic contact with the protruding end of the motor shaft. The shaft current and voltage are then released to the ground through the connecting wires. With this device, the motor shaft is grounded through the carbon brushes, forming an external circuit. The shaft voltage on the motor shaft is released through this circuit, and the shaft current will not flow through the motor bearings. The application of this device effectively ensures the safe operation of the motor. It is simple, reliable, easy to install, uses few parts, and is suitable for widespread application. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0015] In the diagram: 1. Mounting bracket; 2. Housing; 3. Retaining ring; 4. Guide post; 5. Spring; 6. Fixed conductor bracket; 7. Fixing base; 8. Carbon brush; 9. Connecting wire. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] Example 1: Please refer to Figure 1 This utility model provides a technical solution:

[0018] A harmonic current release device for a variable frequency motor includes a housing 2, a retaining ring 3, and a retaining conductor frame 6.

[0019] The inner side of the outer shell 2 is slidably connected to a fixing ring 3, and the inner side of the fixing ring 3 is fixedly connected to a guide post 4. One end of the guide post 4 is slidably connected to a fixing conductor frame 6, and the outer side of the fixing conductor frame 6 is fixedly connected to the outer shell 2. The other end of the fixing conductor frame 6 is fixedly connected to a connecting wire 9, and the other end of the connecting wire 9 is grounded.

[0020] The other end of the guide post 4 is fixedly connected to a fixing seat 7, and the other end of the fixing seat 7 is fixedly connected to a carbon brush 8.

[0021] The outer side of the aforementioned housing 2 is fixedly connected to a mounting bracket 1, and the mounting bracket 1 is L-shaped. The outer side of the aforementioned mounting bracket 1 is provided with evenly distributed threaded holes.

[0022] A spring 5 is provided on the outside of the guide post 4. One end of the spring 5 is fixedly connected to the fixed conductor frame 6, and the other end of the spring 5 is fixedly connected to a fixing ring 3.

[0023] The carbon brush 8 has an arc-shaped end facing away from the mounting base 7.

[0024] The aforementioned fixed conductor frame 6 has a hollow cylinder at one end facing the guide post 4, and the guide post 4 is disposed inside the hollow cylinder and is slidably connected to it.

[0025] Working Process: In an ideal AC induction motor, the magnetic field is symmetrical. When the currents in the three-phase windings are equal and the phase difference is 120°, no voltage is induced on the motor shaft. When the inverter outputs a PWM voltage, causing an asymmetry in the internal magnetic field of the motor, a voltage is induced on the shaft. The higher the drive voltage, the higher the voltage on the shaft. When this voltage exceeds the insulation strength of the lubricating oil in the bearing, a current path is formed. During shaft rotation, an electric arc is generated at a certain point, burning the surfaces of the shaft, balls, and cups, forming pits. In the initial stage of motor operation, when the lubricating oil temperature is low, the current amplitude is 5-200mA. Such a small current will not cause any damage to the bearing. However, after the motor has been running for a period of time, as the lubricating oil temperature rises, the peak current will reach 5-1... 0A can cause flashover, forming small pits on the surface of bearing parts. Excessive frequency conversion harmonic current can lead to excessive shaft current, causing bearing erosion. This results in bearing sliding, dragging the bearing outer ring for frictional movement, causing bearing housing deformation. The high temperature released by the partial discharge energy of the shaft current can melt the inner ring, outer ring, or ball surface of the bearing, forming grooves, thus generating noise and vibration. If not detected and treated in time, it will lead to bearing failure. The most significant feature of high-frequency shaft current erosion of bearings in frequency conversion speed control systems is the formation of dense, "washboard"-like grooves on the inner and outer rings and balls of the motor bearing. However, in the use of this device, the motor shaft is grounded through carbon brushes, forming an external circuit. The shaft voltage on the motor shaft is released through this circuit, and the shaft current does not flow through the motor bearing. The application of this device effectively ensures the safe operation of the motor. It is simple, reliable, easy to install, uses few components, and is suitable for widespread application. Specifically, the outer casing 2 is fixed to the outer casing of the bare shaft at the protruding end of the motor shaft via the mounting bracket 1, or to other locations, as long as the fixing function is achieved. At this time, the carbon brush 8 is in elastic contact with the motor shaft. When the motor rotates, the spring 5 at the rear end of the carbon brush 8 maintains the elastic contact between the carbon brush 8 and the protruding end of the motor shaft. Then, the shaft current and voltage are released to the ground through the connected wire 9. With this device, the motor shaft is grounded through the carbon brush 8, forming an external circuit, and the shaft voltage on the motor shaft is... With this circuit released, shaft current will not flow through the motor bearing. The application of this device effectively ensures the safe operation of the motor. It is simple, reliable, easy to install, uses few parts, and is suitable for widespread application. Furthermore, the guide post 4 and the fixed conductor frame 6 are internally slidably connected, which provides a certain degree of elasticity. When the carbon brush 8 is externally squeezed, it can automatically adjust to ensure close contact between the two. The guide post 4 and the fixed conductor frame 6 can be disassembled, and parts can be replaced when damaged. The guide post 4, fixed conductor frame 6, fixed seat 7, carbon brush 8, and connecting wire 9 are all made of conductive materials, which facilitates the release of current.

[0026] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0027] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A harmonic current release device for variable frequency motor, characterized in that: it comprises a shell (2), a fixed ring (3) and a fixed conductor frame (6); the inside of the shell (2) is slidably connected with the fixed ring (3), the inside of the fixed ring (3) is fixedly connected with a guide column (4), one end of the guide column (4) is slidably connected with the fixed conductor frame (6), the outside of the fixed conductor frame (6) is fixedly connected with the shell (2), the other end of the fixed conductor frame (6) is fixedly connected with a connecting wire (9), and the other end of the connecting wire (9) is grounded; the other end of the guide column (4) is fixedly connected with a fixed seat (7), and the other end of the fixed seat (7) is fixedly connected with a carbon brush (8). The outside of the shell (2) is fixedly connected with a mounting bracket (1), and the mounting bracket (1) is L-shaped, the outside of the mounting bracket (1) is provided with uniformly distributed threaded holes.

2. A harmonic current releasing device for a variable frequency motor as defined in claim 1, characterized in that: The outside of the guide column (4) is provided with a spring (5), one end of the spring (5) is fixedly connected with the fixed conductor frame (6), and the other end of the spring (5) is fixedly connected with the fixed ring (3).

3. A harmonic current releasing device for a variable frequency motor as defined in claim 1, characterized in that: The end of the carbon brush (8) away from the fixed seat (7) is arc-shaped.

4. A harmonic current releasing device for a variable frequency motor according to claim 1, characterized in that: The end of the fixed conductor frame (6) facing the guide column (4) is provided with a hollow cylinder, and the guide column (4) is arranged in the hollow hole and is slidably connected with the hollow hole.

5. A harmonic current releasing device for a variable frequency motor as defined in claim 1, wherein: ​

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