Brush holder structure of direct current permanent magnet motor capable of weakening electromagnetic interference

Abstract

The utility model provides a kind of DC permanent magnet motor brush holder structure that can weaken electromagnetic interference, it is related to motor brush holder technical field.Brush holder structure includes brush cover, the brush cover is also equipped with brush holder plate and electromagnetic compatibility board, wherein the brush holder plate is perpendicular to the rotating shaft of DC permanent magnet motor, the brush holder plate is equipped with brush, inductance and motor lead wire, the motor lead wire is stretched out after from brush holder plate and passes through the outer peripheral wall of brush cover;The electromagnetic compatibility board is installed in the inboard of the outer peripheral wall of brush cover with the attitude perpendicular to motor lead wire, the electromagnetic compatibility board is electrically connected with brush cover and brush holder plate respectively, and the electromagnetic compatibility board is equipped with anti-electromagnetic interference element.Based on this, the utility model can realize the effective weakening of electromagnetic interference, solve the electromagnetic interference phenomenon for DC permanent magnet motor, and the problem that effective application scheme has not appeared in prior art.

Description

Technical Field

[0001] This utility model relates to the field of electric motor brush holder technology, specifically a brush holder structure for a DC permanent magnet electric motor that can reduce electromagnetic interference. Background Technology

[0002] DC permanent magnet motors, with their advantages of ease of use and convenient forward and reverse drive, have been widely used in the automotive industry and various industrial drive applications. Their working principle involves the sliding of brushes on the commutator to achieve electrical connection and conversion between the armature coil and the external power supply. However, during operation, as the brushes pass through each commutator segment, the direction of the armature current changes, causing the current in the armature coil to exhibit an alternating pulsating state. Due to this characteristic, DC motors generate interference during operation. This interference propagates externally through both conduction and radiation, causing wide-band electromagnetic interference to other electrical appliances and affecting their operational stability.

[0003] Currently, people's demands for automotive performance and industrial drive performance are constantly increasing, making it essential to address the aforementioned electromagnetic interference (EMI) issues in the field of DC permanent magnet motors. However, in existing technologies, due to the differences in the electromagnetic structure, ferromagnetic materials, operating voltage, and speed of various DC permanent magnet motors, a universal solution for reducing EMI has not yet emerged. Furthermore, many motor manufacturers on the market often lack electromagnetic compatibility (EMC) testing laboratories, making it difficult to verify preliminary EMC solutions during the initial design phase. Choosing to conduct testing and rectification at a third-party laboratory is not only costly but also requires technical personnel to be on-site to adjust the solution in real time based on the test results, resulting in high labor costs.

[0004] In summary, this utility model provides a brush holder structure for a DC permanent magnet motor that can reduce electromagnetic interference. Utility Model Content

[0005] The purpose of this invention is to provide a brush holder structure for a DC permanent magnet motor that can reduce electromagnetic interference, in order to solve the problem mentioned in the background art that there is no effective application solution for the electromagnetic interference phenomenon of DC permanent magnet motors in the prior art.

[0006] This utility model is achieved using the following technical solution:

[0007] A brush holder structure for a DC permanent magnet motor that can reduce electromagnetic interference includes a brush cover, a brush holder plate and an electromagnetic compatibility (EMC) plate on the brush cover, wherein the brush holder plate is perpendicular to the shaft of the DC permanent magnet motor, and the brush holder plate is provided with brushes, inductors and motor leads, the motor leads extending from the brush holder plate and passing through the outer peripheral wall of the brush cover; the EMC plate is installed on the inner side of the outer peripheral wall of the brush cover in an orientation perpendicular to the motor leads, the EMC plate is electrically connected to both the brush cover and the brush holder plate, and the EMC plate is provided with electromagnetic interference suppression components.

[0008] The brush holder structure provided by this utility model, through the reasonable arrangement of the brush holder plate, allows for the installation of brushes and inductors. This ensures a reliable circumferential connection between the brushes and the commutator while simultaneously reducing harmonic interference caused by transient currents through the inductor. More notably, an electromagnetic compatibility (EMC) plate, installed perpendicular to the motor leads, is incorporated, and anti-EMC components are mounted on it. This significantly reduces the energy of electromagnetic interference transmitted to other electrical appliances via wires, effectively mitigating EMC. In actual production of DC permanent magnet motors, by setting the aforementioned brush holder plate and EMC plate, and reasonably configuring the parameters of the anti-EMC components on both plates, the produced DC permanent magnet motor can possess considerable anti-EMC capabilities. Therefore, the number of preliminary tests in EMC testing can be effectively reduced, and only minor adjustments to component values ​​may be needed based on test results. This allows for faster fulfillment of EMC requirements, effectively saving testing costs, labor costs, and time costs.

[0009] Furthermore, the inductors include inductor I and inductor II, which are symmetrically distributed on the brush holder plate. Inductors I and II, together with the armature, form the main current circuit of the DC permanent magnet motor. Inductors I and II can reduce the rise and fall rates of the motor current, thereby mitigating harmonic interference caused by transient currents.

[0010] Furthermore, the brush holder board is also equipped with a surface-mount TVS diode and a BDL filter I, which are respectively connected between the positive and negative terminals of the power supply. The aforementioned surface-mount TVS diode (bidirectional transient diode) is used to suppress the reverse pulse voltage generated when the motor is turned off, so as to meet the requirements of the transient emission interference standard; the BDL filter I is a typical bandpass filter used to suppress differential-mode and common-mode noise. By selecting different frequencies of BDL filter I, the attenuation value at different frequencies can be met.

[0011] Furthermore, the electromagnetic interference suppression components include a surface-mount common-mode capacitor I, a surface-mount common-mode capacitor II, a surface-mount differential-mode capacitor, and a BDL filter II. The aforementioned surface-mount common-mode capacitor I, surface-mount common-mode capacitor II, and surface-mount differential-mode capacitor can be used to reduce common-mode and differential-mode current interference.

[0012] Furthermore, the motor lead wire is provided with a conductive connector, which is electrically connected to the internal core wire of the motor lead wire; one end of the electromagnetic compatibility board is provided with a groove, and the conductive connector is engaged in the groove. The aforementioned conductive connector is used to realize the electrical connection between the motor lead wire and the anti-electromagnetic interference components on the electromagnetic compatibility board, thereby achieving the effects of differential-mode noise reduction and common-mode noise reduction.

[0013] Furthermore, a cable exit sleeve is provided on the inner side of the outer peripheral wall of the brush cover. The motor lead wire passes through the cable exit sleeve and exits the brush cover. The electromagnetic compatibility board is located inside the cable exit sleeve. The cable exit sleeve is used for dust and water protection. Preferably, the cable exit sleeve is set tightly against the inner side of the outer peripheral wall of the brush cover, and the electromagnetic compatibility board is preferably set tightly against the cable exit sleeve. This allows the electromagnetic compatibility board to be located in the outermost position, thereby minimizing the amplitude of electromagnetic interference propagating along the motor lead wire and achieving better electromagnetic compatibility results.

[0014] Furthermore, the electromagnetic compatibility board is provided with a common ground terminal, which is connected (via conductive rubber) to the metal end cover or housing of the DC permanent magnet motor. The electromagnetic compatibility board, by connecting to the metal end cover or housing of the motor via the common ground terminal, achieves a common grounding effect.

[0015] The beneficial effects achieved by this utility model are:

[0016] A brush holder structure for a DC permanent magnet motor is provided. By incorporating a brush holder plate and an electromagnetic compatibility (EMC) plate, along with anti-EMC components on both plates, harmonic interference caused by transient currents can be reduced, and the energy of EMC transmitted to other electrical appliances through wires can be weakened. Based on this, compared with existing technologies, this brush holder structure can effectively reduce EMC interference, thereby reducing the number of preliminary tests in EMC testing and meeting EMC requirements more quickly, thus effectively saving testing costs, labor costs, and time costs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the brush holder structure described in this embodiment of the utility model;

[0018] Figure 2 This is a schematic diagram of the brush holder plate in the brush holder structure described in this embodiment of the utility model;

[0019] Figure 3 This is a front view of the electromagnetic compatibility board in the brush holder structure described in this embodiment of the utility model;

[0020] Figure 4 This is a side view of the electromagnetic compatibility board in the brush holder structure described in this embodiment of the utility model;

[0021] Figure 5 This is a schematic diagram of the circuit connection of the components in the brush holder structure described in this embodiment of the utility model;

[0022] In the diagram: 1. Brush holder plate; 2. Combination screw; 3. M3 screw; 4. Electromagnetic compatibility board; 5. Outlet sleeve; 6. Brush cover; 7. Brush; 8. Inductor I; 9. BDL filter I; 10. Motor lead wire; 11. Conductive connection clip; 12. Surface mount TVS diode; 13. Inductor II; 14. PCB brush holder; 15. Surface mount common mode capacitor I; 16. Double-sided PCB board; 17. BDL filter II; 18. Surface mount differential mode capacitor; 19. Surface mount common mode capacitor II; 20. Conductive rubber; 21. Armature. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0024] Example 1

[0025] This embodiment provides a brush holder structure that can reduce electromagnetic interference, suitable for small DC permanent magnet motors. Please refer to [reference needed]. Figures 1 to 5 This brush holder structure includes a cylindrical brush cover 6 with a central shaft hole. A brush holder plate 1 and an electromagnetic compatibility (EMC) plate 4 are mounted on the brush cover 6. The EMC plate 4 is electrically connected to both the brush cover 6 and the brush holder plate 1. The EMC plate 4 is equipped with electromagnetic interference suppression components. Specifically:

[0026] The brush holder plate 1 includes an annular PCB brush holder 14, which is perpendicular to the shaft of the DC permanent magnet motor and is mounted on the brush cover 6 by combination screws 2. The PCB brush holder 14 has a pair of brushes 7 that cooperate with the motor commutator (in other embodiments, two pairs of brushes 7 may also be provided), and two motor lead wires 10 that are respectively connected to the positive and negative terminals of the external power supply. The two motor lead wires 10 extend from the brush holder plate 1 and pass through a lead sleeve 5 to exit the outer peripheral wall of the brush cover 6, with the lead sleeve 5 tightly attached to the inner side of the outer peripheral wall of the brush cover 6. The PCB brush holder 14 also includes an inductor I 8, an inductor II 13, a surface-mount TVS diode 12, and a BDL filter I 9. Inductors I 8 and II 13 are symmetrically distributed on the brush holder plate 1, and together with the armature 21, they form the main current circuit of the DC permanent magnet motor. The surface-mount TVS diode 12 and the BDL filter I 9 are respectively connected between the positive and negative terminals of the power supply.

[0027] The electromagnetic compatibility board 4 includes a double-sided PCB board 16, which is mounted on the inner side of the outer peripheral wall of the brush cover 6 with M3 screws 3, perpendicular to the motor lead wires 10 and closely attached to the lead wire sleeve 5. Each of the two motor lead wires 10 extending from the brush holder plate 1 is equipped with a conductive connector 11, which is electrically connected to the internal core wire of the motor lead wire 10. One end of the double-sided PCB board 16 has a groove, and the conductive connector 11 is engaged in the groove through a mating relationship. The electromagnetic interference suppression components on the double-sided PCB board 16 include a surface-mount common-mode capacitor I 15, a surface-mount common-mode capacitor II 19, a surface-mount differential-mode capacitor 18, and a BDL filter II 17. The surface-mount differential-mode capacitor 18 and the BDL filter II 17 are connected between the positive and negative terminals of the power supply, respectively, while the surface-mount common-mode capacitors I 15 and II 19 are connected between the positive and negative terminals of the power supply and ground. The electromagnetic compatibility board 4 is also equipped with a common grounding terminal, which is connected to the metal end cover or housing of the DC permanent magnet motor through a conductive rubber 20.

[0028] In the above structure, by setting the brush holder board 1 and the electromagnetic compatibility board 4, electromagnetic interference can be effectively reduced. Specifically: the inductors I 8 and II 13 on the brush holder board 1 can reduce the rise and fall speed of the motor current, thereby reducing harmonic interference caused by transient current; the surface-mount TVS diode 12 (bidirectional transient diode) is used to suppress the reverse pulse voltage generated when the motor is turned off, so as to meet the requirements of the transient emission interference standard. The electromagnetic compatibility board 4 can reduce the energy of electromagnetic interference transmitted to other electrical appliances through the wires. Among them, the BDL filter I 9 and BDL filter II 17 are used to suppress differential mode and common mode noise. By selecting BDL filter I 9 and BDL filter II 17 of different frequencies, the attenuation value at different frequencies can be met; the surface-mount common mode capacitor I 15, surface-mount common mode capacitor II 19, and surface-mount differential mode capacitor 18 can be used to reduce common mode and differential mode current interference.

[0029] Therefore, in practical applications, the values ​​of the BDL filter, inductor, and capacitor in the brush holder structure can be reasonably set according to the rated voltage, speed, and current of the DC permanent magnet motor. This brush holder structure design can be referenced for DC permanent magnet motors of different voltages and power levels. In actual production of DC permanent magnet motors, by setting the aforementioned brush holder plate 1 and electromagnetic compatibility plate 4, and reasonably setting the parameters of the anti-electromagnetic interference components on both plates, the produced DC permanent magnet motor can possess considerable anti-electromagnetic interference capabilities. Therefore, the number of preliminary tests in electromagnetic compatibility testing can be effectively reduced, and it may only require fine-tuning of component values ​​based on test results, thus quickly meeting electromagnetic compatibility requirements and effectively saving testing costs, labor costs, and time costs.

[0030] It should be noted that the parts not described in detail or in an elaborate manner in the above solution are all prior art, not improvements made by this utility model to the prior art, nor are they within the protection scope of this utility model's technical solution. Therefore, they will not be elaborated upon in this article.

[0031] Of course, the above description is only a preferred embodiment of this utility model and should not be considered as limiting the scope of the embodiments of this utility model. This utility model is not limited to the above examples, and all equivalent changes and improvements made by those skilled in the art within the scope of this utility model should be included in the patent coverage of this utility model.

Claims

1. A brush holder structure for a DC permanent magnet motor that can reduce electromagnetic interference, comprising a brush cover (6), characterized in that: The brush cover (6) is also provided with a brush holder plate (1) and an electromagnetic compatibility plate (4). The brush holder plate (1) is perpendicular to the shaft of the DC permanent magnet motor. The brush holder plate (1) is provided with a brush (7), an inductor and a motor lead wire (10). The motor lead wire (10) extends out of the brush holder plate (1) and passes through the outer peripheral wall of the brush cover (6). The electromagnetic compatibility plate (4) is installed on the inner side of the outer peripheral wall of the brush cover (6) in a position perpendicular to the motor lead wire (10). The electromagnetic compatibility plate (4) is electrically connected to the brush cover (6) and the brush holder plate (1) respectively. The electromagnetic compatibility plate (4) is provided with anti-electromagnetic interference elements.

2. The DC permanent magnet motor brush holder structure for reducing electromagnetic interference according to claim 1, characterized in that: The inductors include inductor I (8) and inductor II (13), which are symmetrically distributed on the brush holder plate (1). The inductors I (8) and inductor II (13) together with the armature (21) constitute the main current circuit of the DC permanent magnet motor.

3. The DC permanent magnet motor brush holder structure for reducing electromagnetic interference according to claim 1, characterized in that: The brush holder plate (1) is also provided with a surface-mount TVS diode (12) and a BDL filter I (9), which are respectively connected between the positive and negative terminals of the power supply.

4. The DC permanent magnet motor brush holder structure for reducing electromagnetic interference according to claim 1, characterized in that: The electromagnetic interference suppression components include a surface-mount common-mode capacitor I (15), a surface-mount common-mode capacitor II (19), a surface-mount differential-mode capacitor (18), and a BDL filter II (17).

5. The DC permanent magnet motor brush holder structure for reducing electromagnetic interference according to claim 1, characterized in that: The motor lead wire (10) is provided with a conductive connector (11), which is electrically connected to the internal core wire of the motor lead wire (10); one end of the electromagnetic compatibility board (4) is provided with a groove, and the conductive connector (11) is snapped into the groove.

6. The DC permanent magnet motor brush holder structure for reducing electromagnetic interference according to claim 1, characterized in that: The brush cover (6) has a wire outlet sleeve (5) on the inner side of its outer peripheral wall. The motor lead wire (10) passes through the wire outlet sleeve (5) and exits the brush cover (6). The electromagnetic compatibility board (4) is located inside the wire outlet sleeve (5).

7. The DC permanent magnet motor brush holder structure for reducing electromagnetic interference according to claim 1, characterized in that: The electromagnetic compatibility board (4) is provided with a common grounding terminal, which is connected to the metal end cover or housing of the DC permanent magnet motor.

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