EMC immunity motor with a capacitive inductive structure

Abstract

The utility model discloses an EMC anti -interference motor with capacitance inductance structure, including motor main part, and motor main part includes metal shell, rotor, stator and insulation support still includes the end cap of setting at metal shell both ends and the two power supply wiring terminal of leading out from one end end cap, LC filter module, LC filter module detachable type installation in the airtight cavity formed by metal shell to and directly electrical connection in the inside of power supply wiring terminal, the utility model discloses a LC filter module and surge absorption module as a whole subsystem, through in the physical original point motor brush spark and winding current mutation of interference generation and the outside power grid of being disturbed between, implant an integral protection barrier of built -in, realized the " shortest path " principle of interference suppression, maximum limit reduced the parasitic inductance and resistance of long lead -in of traditional external filtering scheme in from, thereby significantly improved the suppression efficiency of high frequency interference.

Description

Technical Field

[0001] This utility model relates to the field of motor technology, and in particular to an EMC anti-interference motor with a capacitor-inductor structure. Background Technology

[0002] In modern industrial automation, smart homes, and precision instrument control, motors serve as core power actuators, and their reliability and stability directly impact the performance of the entire system. With the rapid development of power electronics technology, the application environment of motors is becoming increasingly complex. Especially in variable frequency drive systems where high-frequency switching devices (such as IGBTs and MOSFETs) are widely used, the motor itself is both a sensitive device to electromagnetic interference and a significant source of interference. During motor operation, physical processes such as spark discharge between brushes and commutator, and drastic changes in winding current generate abundant electromagnetic noise. This noise is conducted outwards through the power lines, potentially interfering with other electronic devices on the same power grid and affecting their normal operation. Therefore, electromagnetic compatibility (EMC) has become a key indicator for evaluating motor product quality, and effectively suppressing the electromagnetic interference generated by motors remains a crucial and ongoing focus in motor design.

[0003] Traditional EMC design typically employs an external filter mounted on the motor. This approach treats the filter as a standalone component, connected to the motor's power terminals via leads, utilizing its LC network to attenuate interference in specific frequency bands. While this method has some effectiveness, the physical distance between the filter and the interference source inevitably introduces additional parasitic inductance and resistance through the connecting leads. These parasitic parameters interact with the filter components, significantly degrading its high-frequency filtering performance, particularly its poor noise suppression above MHz. Furthermore, the external filter module increases system size and wiring complexity, limiting its application in space-constrained or highly integrated scenarios.

[0004] Therefore, it is necessary to provide an EMC anti-interference motor with a capacitor-inductor structure to solve the above-mentioned technical problems. Utility Model Content

[0005] The purpose of this invention is to provide an EMC anti-interference motor with a capacitor-inductor structure to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following solution to the aforementioned technical problems: an EMC anti-interference motor with a capacitor-inductor structure, comprising a motor body, the motor body including a metal casing, a rotor, a stator, and an insulating support, and further comprising:

[0007] End caps are provided at both ends of the metal casing and two power terminals are led out from one end cap.

[0008] An LC filter module is detachably installed in a sealed cavity formed by the metal casing and directly electrically connected to the inside of the power supply terminal block. The LC filter module is installed in the metal casing by a snap-fit ​​structure.

[0009] A surge absorption module is encapsulated within a sealed cavity of the metal casing and connected in parallel with the power supply terminals.

[0010] As a further embodiment of this utility model, the LC filter module consists of a surface-mount power inductor and at least one ceramic capacitor. The surface-mount power inductor is connected in series in the conductive path of at least one power supply terminal, and the ceramic capacitor is connected in parallel between two power supply terminals of the surface-mount power inductor on the side closest to the internal winding of the motor.

[0011] As a further embodiment of this invention, the surface-mount power inductor and the ceramic capacitor together constitute a low-pass filter with a cutoff frequency not higher than MHz.

[0012] As a further embodiment of this invention, the surge absorption module is a varistor, which is connected in parallel across the ceramic capacitor.

[0013] As a further embodiment of this utility model, the insulating bracket is fixed to the end of the metal shell, and the surface mount power inductor, the ceramic capacitor and the varistor are all fixed in a specific slot of the insulating bracket by thermally conductive adhesive.

[0014] As a further embodiment of this utility model, a ferrite bead is fitted onto each of the two power supply terminals at the position where they pass through the end cover.

[0015] As a further embodiment of this utility model, the metal shell has multiple slots on its side.

[0016] Compared with the prior art, the beneficial effects of this utility model are:

[0017] 1. By treating the LC filter module and surge absorption module as a single subsystem, this structure achieves fundamental interference control by embedding a built-in, integrated protective barrier between the physical origin of interference generation (motor brush sparks and winding current mutations) and the disturbed external power grid. The LC filter module is responsible for actively filtering out broadband high-frequency conducted noise, while the surge absorption module is responsible for dealing with transient high-voltage spikes. This achieves the "shortest path" principle for interference suppression, minimizing the parasitic inductance and resistance introduced by long leads in traditional external filtering schemes, thereby significantly improving the high-frequency interference suppression efficiency.

[0018] 2. By setting the filter's cutoff frequency to this value or below, it can be ensured that the filter provides sufficiently high insertion loss in the most severe interference frequency band, ensuring that the LC resonant circuit it forms can effectively attenuate the target interference frequency band. This allows the motor of this invention to easily meet the limit requirements of standards such as CISPR and EN in the KHz to MHz frequency band when performing standard EMC conducted emission tests, avoiding the tedious process of repeatedly debugging external filter circuits in traditional designs; 3. When high-frequency common-mode interference currents of equal magnitude and in the same direction attempt to flow out through the power line, the ferrite bead will exhibit high inductive reactance, acting as a "high-frequency barrier." It complements the built-in LC filter, further enhancing the motor's ability to suppress radiated interference. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0020] Figure 1 The overall three-dimensional structure of this utility model Figure 1 ;

[0021] Figure 2 This is a schematic diagram of the overall front view of the present invention;

[0022] Figure 3 The overall three-dimensional structure of this utility model Figure 2 ;

[0023] Figure 4 This is a schematic cross-sectional view of the overall structure of this utility model.

[0024] The attached diagram lists the components represented by each number as follows:

[0025] 1. Motor body; 101. Metal casing; 102. End cover; 103. Power terminal block; 2. LC filter module; 201. Surface mount power inductor; 202. Ceramic capacitor; 3. Surge absorption module; 301. Varistor; 4. Insulating bracket; 5. Ferrite bead; 6. Slot; 7. Rotor; 8. Stator. Detailed Implementation

[0026] The present invention will be further described below with reference to the embodiments.

[0027] Please see Figure 1-4 This utility model provides an EMC anti-interference motor with a capacitor-inductor structure, including a motor body 1, which includes a metal shell 101, a rotor 7, a stator 8, and an insulating support 4. It also includes end caps 102 at both ends of the metal shell 101 and two power terminals 103 extending from one end cap; an LC filter module 2, which is detachably installed within the sealed cavity formed by the metal shell 101 and directly electrically connected to the inside of the power terminals 103. The LC filter module 2 is installed inside the metal shell 101 via a snap-fit ​​structure; and a surge absorption module 3, which is encapsulated within the sealed cavity of the metal shell 101 and connected to the power terminals 103. The source terminal 103 is connected in parallel. In specific operation, by treating the LC filter module 2 and the surge absorption module 3 as a whole subsystem, this structure implants a built-in, integrated protective barrier between the physical origin of the interference, the motor brush spark and the sudden change in winding current, and the disturbed external power grid, thus achieving fundamental interference control. The LC filter module 2 is responsible for actively filtering out high-frequency conducted noise in the wideband, while the surge absorption module 3 is responsible for dealing with transient high-voltage spikes. This achieves the "shortest path" principle of interference suppression, minimizing the parasitic inductance and resistance introduced by long leads in traditional external filtering schemes, thereby significantly improving the high-frequency interference suppression efficiency.

[0028] Further as Figure 2 , Figure 3 and Figure 4 As shown, it is worth noting that the LC filter module 2 consists of a surface-mount power inductor and at least one ceramic capacitor. The surface-mount power inductor is connected in series in the conductive path of at least one power terminal 103, and the ceramic capacitor is connected in parallel between two power terminals 103 of the surface-mount power inductor on the side closest to the internal winding of the motor. The surface-mount power inductor, as a series element, presents high impedance to high-frequency interference, hindering its propagation through the power lines. The ceramic capacitor, as a parallel element, provides a low-impedance discharge path to ground for high-frequency noise passing through the inductor, causing it to be short-circuited and consumed within the motor. This "inductor-capacitor" combination structure, compared to RC filtering using only capacitors, has a superior suppression effect on mid-to-low frequency interference while effectively filtering out high-frequency noise. It achieves full-frequency, high-efficiency suppression of motor interference. Furthermore, the use of surface-mount components offers advantages such as small size, high mechanical strength, suitability for automated production, and ease of integration within the limited internal space of the motor.

[0029] A surface-mount power inductor and a ceramic capacitor together form a low-pass filter with a cutoff frequency of no more than 1MHz. By setting the cutoff frequency of the filter at or below this value, it can be ensured that the filter can provide sufficiently high insertion loss in the frequency band with the most severe interference, so that the LC resonant circuit formed by it can effectively attenuate the target interference frequency band. This allows the motor of this invention to easily meet the limit requirements of standards such as CISPR25 and EN55025 in the 150KHz to 30MHz frequency band when performing standard EMC conducted emission tests, avoiding the tedious process of repeatedly debugging external filter circuits in traditional designs.

[0030] Further as Figure 4 As shown, it is worth noting that surge absorption module 3 is a varistor connected in parallel across the ceramic capacitor. By directly connecting the varistor in parallel across the ceramic capacitor, the nonlinear volt-ampere characteristic of the varistor is utilized: under normal operation, the voltage across its terminals is lower than the varistor voltage, exhibiting a high resistance state, equivalent to an open circuit, which does not affect the circuit operation and will not affect the filtering characteristics of the LC filter. When the motor stalls, a sudden power outage generates back electromotive force, or a surge voltage from the power grid causes the input voltage to rise sharply and exceed the varistor voltage, its resistance will drop sharply to near short circuit, instantly discharging thousands of amperes of surge current, thereby clamping the voltage to a safe level. This ensures that it does not malfunction within the normal voltage fluctuation range and can respond promptly to most operational overvoltages and induced lightning surges.

[0031] Further as Figure 3 As shown, it is worth noting that the insulating bracket 4 is fixed to the end of the metal housing 101, and the surface-mount power inductor, ceramic capacitor and varistor are all fixed in the specific slot of the insulating bracket 4 by thermally conductive adhesive.

[0032] Further as Figure 1 and Figure 2 As shown, it is worth noting that each of the two power supply terminals 103 is fitted with a ferrite bead 5 at the position where it passes through the end cover 102. When a high-frequency common-mode interference current of equal magnitude and in the same direction attempts to flow out through the power line, the ferrite bead 5 will exhibit a high inductive reactance, acting as a "high-frequency barrier". It complements the built-in LC filter, further enhancing the motor's ability to suppress radiated interference.

[0033] Further as Figure 2 As shown, it is worth noting that multiple slots 6 are provided on the side of the metal casing 101.

[0034] In summary, by treating the LC filter module 2 and surge absorption module 3 as a single subsystem, this structure achieves fundamental interference control by embedding a built-in, integrated protective barrier between the physical origin of interference generation (motor brush sparks and winding current abrupt changes) and the disturbed external power grid. The LC filter module 2 is responsible for actively filtering out broadband high-frequency conducted noise, while the surge absorption module 3 is responsible for dealing with transient high-voltage spikes. This achieves the "shortest path" principle for interference suppression, minimizing the parasitic inductance and resistance introduced by long leads in traditional external filtering schemes, thereby significantly improving the high-frequency interference suppression efficiency.

Claims

1. An EMC anti-interference motor with a capacitor-inductor structure, comprising a motor body (1), wherein the motor body (1) includes a metal shell (101), a rotor (7), a stator (8), and an insulating support (4), characterized in that, Also includes: End caps (102) are provided at both ends of the metal casing (101) and two power terminals (103) are led out from one end cap. LC filter module (2), the LC filter module (2) is detachably installed in the sealed cavity formed by the metal shell (101) and directly electrically connected to the inside of the power supply terminal (103). The LC filter module (2) is installed in the metal shell (101) by a snap-fit ​​structure. Surge absorption module (3), which is encapsulated in the sealed cavity of the metal shell (101) and connected in parallel with the power supply terminal (103).

2. The EMC anti-interference motor with a capacitor-inductor structure according to claim 1, characterized in that: The LC filter module (2) consists of a surface mount power inductor (201) and at least one ceramic capacitor (202). The surface mount power inductor (201) is connected in series in the conductive path of at least one power terminal (103), and the ceramic capacitor (202) is connected in parallel between two power terminals (103) of the surface mount power inductor (201) near the internal winding of the motor.

3. The EMC anti-interference motor with a capacitor-inductor structure according to claim 2, characterized in that: The surface-mount power inductor (201) and the ceramic capacitor (202) together constitute a low-pass filter with a cutoff frequency not higher than 1MHz.

4. An EMC anti-interference motor with a capacitor-inductor structure according to claim 2, characterized in that: The surge absorption module (3) is a varistor (301), which is connected in parallel across the ceramic capacitor (202).

5. An EMC anti-interference motor with a capacitor-inductor structure according to claim 4, characterized in that: The insulating bracket (4) is fixed to the end of the metal shell (101), and the surface mount power inductor (201), the ceramic capacitor (202) and the varistor (301) are all fixed in a specific slot of the insulating bracket (4) by thermally conductive adhesive.

6. An EMC anti-interference motor with a capacitor-inductor structure according to claim 5, characterized in that: Each of the two power supply terminals (103) is fitted with a ferrite bead (5) at a position where it passes through the end cap (102).

7. An EMC anti-interference motor with a capacitor-inductor structure according to claim 1, characterized in that: The metal casing (101) has multiple slots (6) on its side.

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