A harmonic elimination device for improving the service life of a variable frequency motor
By introducing an active filter and a heat dissipation and dust removal mechanism into the harmonic suppression device, the problem of poor heat dissipation and dust removal performance is solved, achieving efficient heat dissipation and dust removal, and improving the service life of the variable frequency motor and the economic benefits of the device.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- DONGGUAN JINZHOU PAPER IND
- Filing Date
- 2025-06-24
- Publication Date
- 2026-06-16
AI Technical Summary
Existing harmonic elimination devices have poor heat dissipation and dust removal performance during use, resulting in excessively high internal temperatures and affecting work efficiency.
A harmonic elimination device comprising an active filter and a heat dissipation and dust removal mechanism was designed. The active filter identifies and generates a compensating current to eliminate harmonics, and the threaded rod and sponge wipe clean the dust from the heat dissipation holes. The suction cup is used to fix the device position, thereby achieving efficient heat dissipation and dust removal.
It effectively reduces the operating temperature of the device, improves heat dissipation efficiency, reduces dust adsorption, lowers maintenance costs and installation complexity, adapts to different installation methods, and has better harmonic suppression effect and economic benefits.
Smart Images
Figure CN224367533U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of harmonic elimination devices, specifically a harmonic elimination device for improving the service life of variable frequency motors. Background Technology
[0002] With the development of modern industry, variable frequency motors (VFMs) are playing an increasingly important role in social life and production. The lifespan of a VFM motor is crucial for the energy conservation and consumption reduction of the entire system. High-order harmonics generated during VFM operation can distort the output voltage. Surge voltages generated when switches close can also be superimposed on the output voltage. These surge voltages have very high peak values and can adversely affect the motor's insulation, even causing insulation breakdown and reducing the motor's lifespan. Furthermore, high-order harmonics can cause torque pulsation in the motor, leading to noise or vibration. Because high-order harmonics significantly reduce the lifespan of variable frequency motors, most designs incorporate capacitors and reactors in the variable frequency power supply for harmonic suppression. While traditional capacitor-reactor systems offer some protection against harmonics, they are costly in practice due to the high price of capacitors and reactors, leading to increased overall costs. Furthermore, they are complex to maintain, have a shorter lifespan, and require cumbersome installation, necessitating a custom-designed distribution cabinet. Active power filters, on the other hand, can identify harmonic components in the variable frequency motor's current or voltage and generate a compensating current (or voltage) with equal amplitude but opposite phase to the detected harmonics, thus eliminating high-order harmonics. However, existing harmonic suppression devices often suffer from poor heat dissipation and dust removal, leading to overheating during prolonged use and impacting efficiency.
[0003] To overcome the aforementioned deficiencies, existing technology (Chinese Patent No. CN220493462U, published on 2024-02-13) provides a microcomputer harmonic suppression device that facilitates heat dissipation, belonging to the technical field of microcomputer harmonic suppression devices. It includes a microcomputer harmonic suppression device body, a heat absorption plate, a heat dissipation plate, and a fan. The microcomputer harmonic suppression device body has openings on both sides, with a mounting block in the middle of each opening. A drive motor is located on the side of the mounting block away from the microcomputer harmonic suppression device body. The output shaft of the drive motor passes through the mounting block and connects to the fan. The heat dissipation plate is located on the side of the fan away from the mounting block, and the heat absorption plate is located on the side of the heat dissipation plate away from the fan. Through the heat dissipation plates on both sides and the fan, heat inside the microcomputer harmonic suppression device body is quickly dissipated, and ventilation holes on the back assist in heat dissipation, thereby reducing the internal temperature, ensuring normal and stable operation of the device, and achieving good heat dissipation effect and high heat dissipation efficiency.
[0004] The aforementioned mechanism protects the power system by utilizing the harmonic suppression device and also assists in heat dissipation through the heat dissipation mechanism. However, in actual use, the ventilation holes tend to attract a lot of dust due to static electricity during heat dissipation, which weakens the heat dissipation performance and affects the efficiency of subsequent heat dissipation. Utility Model Content
[0005] The purpose of this utility model is to provide a harmonic elimination device that improves the service life of variable frequency motors, in order to solve the problem mentioned in the background art that the existing harmonic elimination devices have poor heat dissipation and dust removal performance during use, which leads to excessive internal temperature during long-term use and affects working efficiency.
[0006] To achieve the above objectives, this utility model provides the following technical solution: a harmonic elimination device for improving the service life of a variable frequency motor, comprising an installation cabinet, wherein a variable frequency motor is installed inside the installation cabinet, an active filter is provided at the lower end of the variable frequency motor, and a variable frequency motor is installed on the side of the active filter via a cable; a heat dissipation hole is provided at the rear end of the installation cabinet, and a heat dissipation and dust removal mechanism for cleaning the installation cabinet is provided at the rear end of the installation cabinet, the heat dissipation and dust removal mechanism includes a threaded rod, and the threaded rod is located at the middle position of the rear end of the installation cabinet, a movable block is threadedly connected to the outer side of the threaded rod, and a sponge is installed at the front end of the movable block; a fixed base plate is installed at the bottom end of the installation cabinet, and a positioning mechanism for fixing the position is installed at the bottom end of the fixed base plate.
[0007] Furthermore, the rear end of the sponge is in contact with the surface of the heat dissipation hole, and the length of the sponge is greater than the length of the heat dissipation hole.
[0008] Furthermore, an elastic airbag is attached to the lower end of the rear end of the installation cabinet, and a squeezing plate is installed on the top of the elastic airbag. The squeezing plate and the installation cabinet are vertically slidably connected. The sponge is placed above the squeezing plate, and a nozzle is installed on the side of the elastic airbag through a flexible tube.
[0009] Furthermore, a slide rail is provided at the rear end of the threaded rod, and a slider is slidably connected inside the slide rail, with the rear end of the movable block connected to the front end of the slider.
[0010] Furthermore, the positioning mechanism includes a fixing rod, which is fixedly connected to the four corners at the bottom of the fixed base plate. A suction cup is installed at the bottom of the fixing rod, and a piston is slidably connected inside the fixing rod. A pull rod is fixedly connected to the top of the piston, and the top of the pull rod passes through and extends to the top of the fixed base plate. A pressing plate is installed at the top of the pull rod.
[0011] Furthermore, a return spring is wound around the outside of the pull rod, and the pressing plate and the fixed base plate form an elastic structure through the return spring.
[0012] Furthermore, each of the four corners at the top of the fixed base plate is provided with an exhaust hole, and a sealing gasket is attached to the top of the exhaust hole, the sealing gasket being sleeved on the outside of the pull rod.
[0013] Compared with the prior art, the beneficial effects of this utility model are:
[0014] 1. In operation, the active power filter first identifies harmonic components in the current or voltage of the variable frequency motor, and then collects the current signal from the variable frequency motor side through a current / voltage sensor. A harmonic separation algorithm is used to extract the harmonic components, separating the fundamental and harmonic waves to obtain the harmonic signals that need compensation. Based on the detected harmonics, a compensation current with equal amplitude but opposite phase is generated, thereby achieving the purpose of eliminating high-order harmonics in the variable frequency motor.
[0015] Furthermore, the use of active power filters can reduce costs. The cost of a single active power filter is very low, only one-twentieth of that of a capacitor and reactor combination harmonic suppression device under the same electrical capacity configuration. Moreover, since there are no capacitors inside the active power filter, there will be no capacitor degradation due to high ambient temperature, reducing maintenance workload. The active power filter is small in size and can be directly connected to the installation cabinet. The input and output terminals of the active power filter can be connected to the output terminal of the frequency converter and the input terminal of the frequency converter motor respectively with cables, making the overall installation convenient.
[0016] Furthermore, this harmonic suppression device supports centralized and distributed installation methods, adapting to different application scenarios. Compared to the capacitor-reactor combination harmonic suppression device, which is only applicable to centralized systems, it is more flexible. The active filter effectively cancels harmonics in the system by detecting harmonic currents in real time and generating opposite compensation currents. It can handle harmonics from the 2nd to the 50th order or even higher. Compared to the capacitor-reactor combination harmonic suppression device, it has a better harmonic suppression effect and is more economical and environmentally friendly.
[0017] 2. The rotation of the motor's output end drives the threaded rod to rotate. The threaded rod is threadedly connected to the movable block, causing the movable block to move downwards. As the movable block moves, it synchronously moves the sponge, which then contacts the surface of the heat dissipation holes. This allows the sponge to clean away any dust remaining on the surface of the heat dissipation holes, thus improving the heat dissipation effect when the heat dissipation holes are used to cool the auxiliary frequency converter and active filter, and reducing the occurrence of dust adhering to the surface of the heat dissipation holes and affecting heat dissipation.
[0018] Furthermore, by pressing down on the fixed base plate, the gas inside the suction cup is reduced. Then, by pressing the pressing plate, the bottom end of the pull rod can extend into the interior of the suction cup and be reset by the elastic force of the return spring, squeezing and expelling the remaining gas inside the suction cup and the gas inside the fixed rod, thereby maintaining a vacuum state inside the suction cup and using the suction cup to fix the device in position. Attached Figure Description
[0019] Figure 1 This is a front view structural diagram of the present utility model.
[0020] Figure 2 This is a schematic diagram of the positioning mechanism of this utility model.
[0021] Figure 3 This is a schematic diagram of the rearview mechanism of this utility model.
[0022] Figure 4 This is a schematic diagram of the heat dissipation and dust removal mechanism of this utility model.
[0023] Figure 5 This is a partially enlarged structural diagram of the heat dissipation and dust removal mechanism of this utility model.
[0024] Figure 6 This is a frontal sectional view of the positioning mechanism of this utility model.
[0025] In the diagram: 1. Mounting cabinet; 2. Inverter; 3. Active filter; 4. Variable frequency motor; 5. Fixed base plate; 6. Fixed rod; 7. Suction cup; 8. Piston; 9. Pull rod; 10. Return spring; 11. Pressing plate; 12. Exhaust hole; 13. Sealing gasket; 14. Heat dissipation hole; 15. Threaded rod; 16. Movable block; 17. Sponge; 18. Slider; 19. Slide rail; 20. Elastic airbag; 21. Extrusion plate; 22. Nozzle. Detailed Implementation
[0026] 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.
[0027] Example 1: As Figure 1 , Figure 3 , Figure 4 and Figure 5The technical solution shown addresses the problem of poor heat dissipation and dust removal performance in existing harmonic suppression devices, which leads to excessively high internal temperatures and reduced efficiency during prolonged use. This harmonic suppression device, designed to improve the lifespan of variable frequency motors, discloses a heat dissipation and dust removal mechanism, including a mounting cabinet 1. A variable frequency drive 2 is installed inside the mounting cabinet 1, and an active filter 3 is located at the lower end of the variable frequency drive 2. A variable frequency motor 4 is mounted on the side of the active filter 3 via a cable. A heat dissipation hole 14 is provided at the rear end of the mounting cabinet 1. A heat dissipation and dust removal mechanism is provided for cleaning the device. The heat dissipation and dust removal mechanism includes a threaded rod 15, which is located at the middle of the rear end of the mounting cabinet 1. A movable block 16 is threadedly connected to the outer side of the threaded rod 15, and a sponge 17 is installed at the front end of the movable block 16. The rear end of the sponge 17 is in contact with the surface of the heat dissipation hole 14, and the length of the sponge 17 is greater than the length of the heat dissipation hole 14. A slide rail 19 is provided at the rear end of the threaded rod 15, and a slider 18 is slidably connected inside the slide rail 19. The rear end of the movable block 16 is connected to the front end of the slider 18.
[0028] In this example, the output terminal of the inverter 2 is directly connected to the three-phase input terminal of the active filter 3 inside the mounting cabinet 1, and then the output terminal of the active filter 3 is connected to the load terminal of the inverter motor 4 with a cable. The connection between the inverter motor 4 and the active filter 3 is achieved through the aforementioned steps. During operation, the active filter 3 first identifies the harmonic components in the current or voltage of the inverter motor 4, and then collects the current signal on the side of the inverter motor 4 through a current / voltage sensor. Harmonic components are extracted using a harmonic separation algorithm, separating the fundamental frequency component from the harmonics to obtain the harmonic signal requiring compensation. Then, based on the detected harmonics, a compensation current or voltage with equal amplitude but opposite phase is generated, thereby eliminating the high-order harmonics of the variable frequency motor 4. The use of an active filter 3 reduces costs; a single active filter 3 has a very low cost, only one-twentieth the cost of a capacitor-reactor combination harmonic elimination device with the same electrical capacity configuration. Furthermore, the active filter 3 does not contain internal capacitors, preventing capacitor degradation due to high ambient temperatures, thus reducing maintenance workload. The active filter 3 is small in size; it can be directly connected to the installation cabinet 1, with its input and output terminals connected to the output of the variable frequency drive 2 and the input of the variable frequency motor 4 via cables. The overall installation is convenient, and this harmonic elimination device supports centralized and distributed installation methods, adapting to different application scenarios. It is more flexible than the capacitor-reactor combination harmonic elimination device, which is only applicable to centralized installations. The active filter 3 effectively eliminates harmonics by detecting the harmonic current in real time and generating an opposite compensation current. The system can cancel harmonics, handling harmonics from the 2nd to the 50th order or even higher. It offers better harmonic cancellation than capacitor-reactor combination devices, and is more economical and environmentally friendly. Rotation of the motor's output drives the threaded rod 15, which is threadedly connected to the movable block 16. This causes the movable block 16 to move downwards, synchronously moving the sponge 17. The sponge 17 contacts the surface of the heat dissipation hole 14, allowing residual dust to be removed. The sponge 17 is used to clean the dust, which allows the heat dissipation holes 14 to achieve better heat dissipation when the auxiliary inverter 2 and active filter 3 are dissipating heat, reducing the occurrence of dust adhering to the surface of the heat dissipation holes 14 and affecting heat dissipation. In addition, during the movement of the movable block 16, the movable block 16 is connected to the slider 18, which allows the slider 18 to slide inside the slide rail 19. This restricts the angle of the movable block 16 by the slider 18 and the slide rail 19, making the overall movement of the movable block 16 smoother and effectively avoiding jamming.
[0029] Example 2: Figure 1 , Figure 3 , Figure 4 and Figure 5The technical solution shown addresses the problem that some dust remains in dead corners during dust removal and cannot be completely cleaned: the harmonic elimination device for improving the service life of variable frequency motors discloses a cleaning mechanism. An elastic airbag 20 is attached to the lower end of the rear end of the mounting cabinet 1, and a squeezing plate 21 is installed on the top of the elastic airbag 20. The squeezing plate 21 and the mounting cabinet 1 are vertically slidably connected. A sponge 17 is placed above the squeezing plate 21, and a nozzle 22 is installed on the side of the elastic airbag 20 through a flexible hose.
[0030] In this example, as the sponge 17 moves downwards, it squeezes the compression plate 21. The bottom end of the compression plate 21 contacts the elastic airbag 20, allowing the compression plate 21 to squeeze the elastic airbag 20. The gas inside the elastic airbag 20 is then delivered to the nozzle 22 through the hose. The height of the nozzle 22 can be adjusted as needed, allowing the nozzle 22 to expel air from the dust remaining inside the heat dissipation hole 14, reducing the amount of dust remaining inside the heat dissipation hole 14. Furthermore, a one-way valve is provided at the air inlet of the elastic airbag 20 to prevent gas from escaping from the air inlet during exhaust. A one-way valve is also provided at the air outlet of the nozzle 22 to prevent gas from being sucked in from the nozzle 22 during the return airbag 20, which could cause dust to be sucked in backwards.
[0031] Example 3: Figure 1 , Figure 2 and Figure 6 The technical solution shown addresses the issue of potential positional shift of the mounting cabinet 1 due to collisions during use. This harmonic elimination device, designed to improve the lifespan of the variable frequency motor, discloses a positioning mechanism. A fixed base plate 5 is installed at the bottom of the mounting cabinet 1, and a positioning mechanism for position fixing is installed at the bottom of the fixed base plate 5. The positioning mechanism includes a fixed rod 6, which is fixedly connected to the four corners at the bottom of the fixed base plate 5. A suction cup 7 is installed at the bottom of the fixed rod 6. A piston 8 is slidably connected inside the fixed rod 6, and a pull rod 9 is fixedly connected to the top of the piston 8. The top of the pull rod 9 passes through and extends to the top of the fixed base plate 5, and a pressing plate 11 is installed at the top of the pull rod 9. A return spring 10 is wound around the outside of the pull rod 9, and the pressing plate 11 and the fixed base plate 5 form an elastic structure through the return spring 10. Vent holes 12 are provided at the four corners at the top of the fixed base plate 5, and a sealing gasket 13 is attached to the top of the vent hole 12, with the sealing gasket 13 fitted onto the outside of the pull rod 9.
[0032] In this example, pressing down on the fixed base plate 5 reduces the gas inside the suction cup 7. Then, pressing the pressing plate 11 extends the bottom end of the pull rod 9 into the suction cup 7 and resets it using the spring force of the return spring 10. This squeezes and discharges the remaining gas inside the suction cup 7 and the gas inside the fixed rod 6, thus maintaining a vacuum inside the suction cup 7 and fixing the device in position using the suction cup 7. Furthermore, each of the four corners at the top of the fixed base plate 5 has an exhaust hole 12, which allows the gas inside the fixed rod 6 to be discharged. At the same time, the sealing gasket 13 seals and blocks the top of the exhaust hole 12. When the gas inside the fixed rod 6 moves upward due to compression, the gas pressure pushes the sealing gasket 13 upward, allowing the gas to be discharged from the exhaust hole 12. After the gas pressure weakens, the spring force of the return spring 10 quickly resets the pressure, allowing the sealing gasket 13 to continue to adsorb and seal the exhaust hole 12.
[0033] 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 elimination device for improving the service life of a variable frequency motor, comprising a mounting cabinet (1), wherein a variable frequency motor (2) is installed inside the mounting cabinet (1), an active filter (3) is provided at the lower end of the variable frequency motor (2), and a variable frequency motor (4) is installed on the side of the active filter (3) via a cable. Its features are: The installation cabinet (1) has a heat dissipation hole (14) at its rear end, and a heat dissipation and dust removal mechanism for cleaning is provided at the rear end of the installation cabinet (1). The heat dissipation and dust removal mechanism includes a threaded rod (15), and the threaded rod (15) is located at the middle position of the rear end of the installation cabinet (1). The outer side of the threaded rod (15) is threaded with a movable block (16), and a sponge wiper (17) is installed at the front end of the movable block (16). The bottom of the mounting cabinet (1) is equipped with a fixed base plate (5), and the bottom of the fixed base plate (5) is equipped with a positioning mechanism for fixing the position.
2. The harmonic elimination device for improving the service life of a variable frequency motor according to claim 1, characterized in that: The rear end of the sponge (17) is in contact with the surface of the heat dissipation hole (14), and the length of the sponge (17) is greater than the length of the heat dissipation hole (14).
3. The harmonic elimination device for improving the service life of a variable frequency motor according to claim 2, characterized in that: An elastic airbag (20) is attached to the lower end of the rear end of the installation cabinet (1), and a squeezing plate (21) is installed on the top of the elastic airbag (20). The squeezing plate (21) and the installation cabinet (1) are vertically slidably connected. The sponge (17) is placed above the squeezing plate (21), and a nozzle (22) is installed on the side of the elastic airbag (20) through a hose.
4. The harmonic elimination device for improving the service life of a variable frequency motor according to claim 3, characterized in that: The threaded rod (15) has a slide rail (19) at its rear end, and a slider (18) is slidably connected inside the slide rail (19). The rear end of the movable block (16) is connected to the front end of the slider (18).
5. The harmonic elimination device for improving the service life of a variable frequency motor according to claim 4, characterized in that: The positioning mechanism includes a fixed rod (6), which is fixedly connected to the four corners of the bottom of the fixed base plate (5). A suction cup (7) is installed at the bottom of the fixed rod (6). A piston (8) is slidably connected inside the fixed rod (6), and a pull rod (9) is fixedly connected to the top of the piston (8). The top of the pull rod (9) passes through and extends to the top of the fixed base plate (5). A pressing plate (11) is installed at the top of the pull rod (9).
6. The harmonic elimination device for improving the service life of a variable frequency motor according to claim 5, characterized in that: The pull rod (9) is wrapped with a return spring (10), and the pressing plate (11) and the fixed base plate (5) form an elastic structure through the return spring (10).
7. The harmonic elimination device for improving the service life of a variable frequency motor according to claim 6, characterized in that: The fixed base plate (5) has four vent holes (12) at the top corners, and the top of the vent holes (12) is fitted with a sealing gasket (13), which is sleeved on the outside of the pull rod (9).