Motor air gap balance monitoring winding

Abstract

The utility model discloses a motor air gap balance monitoring winding, which relates to the technical field of motor air gap balance monitoring and comprises a stator core, a main winding, a monitoring winding assembly, a voltage detector, a threshold judging device, a harmonic analyzer and an electromagnetic shielding layer. The electromagnetic induction principle is directly utilized to monitor the air gap change, an additional sensor is not needed, the cost is remarkably reduced, the device can be easily integrated into an existing motor structure, the micron-sized air gap change can be detected earlier and more accurately, the monitoring sensitivity and accuracy are improved, the phase information of the winding voltage is analyzed and monitored through the harmonic analyzer, and the monitoring accuracy is improved. The air gap unbalance direction can be accurately judged, more accurate guidance is provided for motor maintenance and fault diagnosis, the threshold value judging device gives out early warning in time when the air gap unbalance exceeds the preset threshold value, motor faults can be prevented, the service life of the motor is prolonged, and downtime and maintenance cost are reduced.

Description

Technical Field

[0001] This utility model relates to the field of motor air gap balance monitoring technology, specifically a motor air gap balance monitoring winding. Background Technology

[0002] As a core power equipment in modern industry, the operating status of electric motors directly affects the reliability and efficiency of production systems. Among the key indicators of motor performance is the uniformity of the air gap. Air gap imbalance can lead to a series of problems, including electromagnetic imbalance, mechanical vibration, bearing wear, and noise pollution. Existing solutions include offline detection, vibration monitoring, current analysis, and monitoring windings. However, offline detection suffers from downtime and cannot achieve continuous monitoring; vibration monitoring is susceptible to mechanical noise interference; current analysis has low sensitivity and is greatly affected by load. Monitoring windings, on the other hand, offer advantages such as low cost, high detection sensitivity, and high accuracy. Examples include the air gap measurement device and method for the CN113014042A motor and its application in wind turbine generator sets. The system includes a measurement circuit and an information collection device. The measurement circuit includes a circuit conductor arranged along the direction of the magnetic field lines cutting the motor on the stator winding assembly. Both ends of the measurement circuit are connected to the information collection device, which collects the induced electromotive force induced by the circuit conductor and determines the air gap value between the stator winding assembly and the rotor assembly of the motor through the induced electromotive force. However, this technical solution cannot effectively solve the interference of the main winding magnetic field on the monitoring winding, nor can it determine the location of the air gap imbalance, and there may be slight imbalances in reality. How to set a threshold to determine whether there is a real problem with the air gap? Utility Model Content

[0003] The purpose of this invention is to provide a motor air gap balance monitoring winding to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, this utility model provides the following technical solution: a motor air gap balance monitoring winding, comprising: a stator core, the stator core being an annular structure with multiple axially extending rectangular stator slots evenly distributed along its inner circumference; a main winding being provided within the stator slots, the main winding being made of multiple strands of insulated copper wire and embedded in the bottom space of the stator slots, continuously distributed along the inner circumference of the stator core; a monitoring winding assembly being provided above the main winding, the monitoring winding assembly comprising two or more independently arranged monitoring windings, the monitoring windings being symmetrically arranged in the unoccupied space above the main windings within the stator slots, evenly distributed along the inner circumference of the stator core; voltage detectors being electrically connected to the beginning and end of the monitoring windings; a threshold detector and a harmonic analyzer being electrically connected to the output of the voltage detectors; an electromagnetic shielding layer being provided between the main windings and the monitoring winding assembly, the electromagnetic shielding layer being an annular thin sheet structure, arranged between the monitoring windings and the main windings, and tightly fitted to the inner wall of the stator slots.

[0005] Furthermore, the monitoring winding is a single continuously wound circular cross-section thin wire with 3-15 turns, and all turns are connected in series. The beginning and end are connected to the insulated wire by welding and are covered with an insulating sleeve.

[0006] Furthermore, the insulated wire has a double-layer insulation structure, with an inner polyimide insulation layer and an outer silicone rubber sheath. The insulated wire is led out from the insulating sleeve at the top of the stator slot and connected to the input terminal of the voltage detector.

[0007] Furthermore, the voltage detector includes a differential amplifier circuit, the input of which is connected to the beginning and end of each monitoring winding via a multi-strand shielded wire.

[0008] Preferably, the harmonic analyzer includes a filter circuit and a digital signal processing chip, and the output of the filter circuit is connected in parallel with the threshold detector.

[0009] Preferably, the spatial relationship between the main winding and the monitoring winding is as follows: the main winding occupies 60-70% of the stator slot depth, and the monitoring winding occupies the remaining 30-40% of the top space, and the two are isolated by an electromagnetic shielding layer.

[0010] Compared with existing technologies, the advantages of this invention are as follows: By setting an independent monitoring winding in the stator slot, this invention directly monitors air gap changes using the principle of electromagnetic induction, eliminating the need for additional sensors, significantly reducing costs, and easily integrating into existing motor structures. It can detect micron-level air gap changes earlier and more accurately, improving monitoring sensitivity and accuracy. Furthermore, by analyzing the phase information of the monitoring winding voltage using a harmonic analyzer, the location of air gap imbalance can be accurately determined, providing more precise guidance for motor maintenance and fault diagnosis. A threshold detector issues a timely warning when air gap imbalance exceeds a preset threshold, helping to prevent motor failures, extend motor lifespan, and reduce downtime and maintenance costs. Finally, by setting an electromagnetic shielding layer, interference from the main winding magnetic field to the monitoring winding is effectively isolated, ensuring that the monitoring results directly reflect the air gap state, unaffected by load current harmonics, thus improving monitoring reliability and accuracy. This technical solution has broad applicability, suitable not only for conventional AC motors but also for various types of motors such as DC motors and permanent magnet motors. This broad applicability makes this technical solution have broad application prospects in the field of motor monitoring. Attached Figure Description

[0011] Fig. 1 This is a flowchart illustrating the process of this utility model.

[0012] Fig. 2 This is a schematic diagram of the structure of the first embodiment of the present utility model;

[0013] Fig. 3 This is a schematic diagram of the structure of the second embodiment of the present utility model;

[0014] In the diagram: 1. Stator core, 2. Main winding, 3. Monitoring winding assembly, 4. Voltage detector, 5. Threshold detector, 6. Harmonic analyzer, 7. Electromagnetic shielding layer, 101. Stator slot, 301. Monitoring winding. Detailed Implementation

[0015] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings and specific embodiments.

[0016] Please refer to Figs. 1-3This utility model provides a motor air gap balance monitoring winding, including: a stator core 1, a main winding 2 and a monitoring winding assembly 3 inside the stator core 1, the stator core 1 having an annular structure, with multiple axially extending rectangular stator slots 101 evenly opened on the inner annular surface, the main winding 2 being made of multiple strands of insulated copper wire and embedded in the stator slots 101, the monitoring winding assembly 3 including two or more independently arranged monitoring windings 301, the monitoring windings 301 being symmetrically distributed along the inner annular surface of the stator core 1 and all monitoring windings 301 being located in the same annular surface, the beginning and end of the monitoring windings 301 being electrically connected to voltage detectors 4, the output end of the voltage detectors 4 being electrically connected to a threshold detector 5 and a harmonic analyzer 6.

[0017] The monitoring winding 301 is symmetrically arranged in the stator core 1, and its first and last sections are electrically connected to the voltage detector 4. Based on the voltage detector 4, the voltage of the monitoring winding 301 is detected. When the air gap is uniform, the induced electromotive force (EMF) amplitude of each phase monitoring winding 301 is equal and the phase is symmetrical, and the vector sum is zero. When the air gap is uneven, the rotor eccentricity or stator deformation causes the air gap of a certain phase to decrease or increase, destroying the symmetry of each phase, and the combined voltage is no longer zero. In reality, there may be a slight imbalance. Based on the threshold judgment device 5 and the motor operating conditions such as temperature and load, the alarm threshold setting is adaptively adjusted. If the effective value of the vector sum exceeds the preset threshold, the air gap is determined to be unbalanced. The harmonic analyzer 6 is used to extract the harmonic components in the voltage of the monitoring winding 301 and to determine the location of the air gap imbalance by comparing the amplitude difference and phase difference of each harmonic.

[0018] The main winding 2 is embedded in the stator slot 101 on the side away from the axis, and the monitoring winding 301 is symmetrically arranged in the stator slot 101 on the side close to the axis, located in the free space above the main winding 2 that is not occupied by the main winding 2.

[0019] The main winding 2 and the monitoring winding 301 share the stator slot 101, which makes full use of the space inside the slot, avoids the need for additional slotting, reduces the volume and weight of the stator core 1, eliminates the need for separate slotting for the monitoring winding 301, avoids complex processing steps, simplifies the manufacturing process, improves production efficiency, and enhances the compactness and integration of the system, making it easier to install and maintain.

[0020] An electromagnetic shielding layer 7 is provided between the main winding 2 and the monitoring winding assembly 3. The electromagnetic shielding layer 7 is an annular thin sheet structure that fits tightly against the inner wall of the stator slot 101.

[0021] The electromagnetic shielding layer 7 reduces electromagnetic interference between the main winding 2 and the monitoring winding 301, ensuring accurate monitoring signals. Preferably, the electromagnetic shielding layer 7 is a permalloy foil or copper mesh shielding structure, which is wrapped in a ring around the outer periphery of the monitoring winding and is tightly fitted to the inner wall of the stator slot. The thickness of the shielding layer is 0.1-0.5mm.

[0022] The spatial relationship between the main winding 2 and the monitoring winding 301 is as follows: the main winding 2 occupies 60-70% of the depth of the stator slot 101, and the monitoring winding 301 occupies the remaining 30-40% of the top.

[0023] Multiple axially extending monitoring winding slots 102 are evenly provided between the stator slots 101, and the monitoring winding 301 is embedded inside the monitoring winding slots 102.

[0024] The monitoring winding 301 and the main winding 2 are respectively embedded in independent stator slots 101 and monitoring winding slots 102, which achieves physical isolation, avoids electromagnetic interference, and improves the purity and accuracy of the monitoring signal.

[0025] The voltage detector 4 includes a differential amplifier circuit, the input of which is connected to the beginning and end of each monitoring winding 301 via a multi-strand shielded wire.

[0026] The differential amplifier circuit receives the signals from the beginning and end of the monitoring winding 301 through two input terminals, amplifies the difference between the two signals, ignores their common-mode components, effectively eliminates external interference signals, and ensures that only the effective signal from the monitoring winding 301 is amplified and processed.

[0027] The harmonic analyzer 6 includes a filter circuit and a digital signal processing chip, and the output of the filter circuit is connected in parallel with the threshold detector 5.

[0028] The filtering circuit removes high-frequency noise and unwanted harmonic components from the signal, retaining useful low-frequency signals. This ensures that the signal has undergone preliminary purification before entering the digital signal processing chip, reducing the complexity of subsequent processing. The digital signal processing chip further processes and analyzes the filtered signal, including harmonic analysis and spectrum analysis, extracting feature information related to motor air gap imbalance, processing and monitoring the winding signal in real time, quickly determining whether the motor air gap is balanced, and issuing alarms or taking corresponding control measures when an anomaly is detected.

[0029] The monitoring winding 301 is a single continuously wound circular cross-section thin wire with 3-15 turns, and all turns are connected in series. The beginning and end are connected to the insulated wire by welding, and the insulated wire is covered with an insulating sleeve.

[0030] The cross-sectional area of ​​the conductor in the monitoring winding 301 is less than one-fifth that of the main winding, and the single thin conductor reduces the influence on the main magnetic field.

[0031] First Embodiment: In this embodiment, the monitoring winding 301 and the main winding 2 share a stator slot 101. The specific structure is as follows: The stator core 1 has a ring structure, and multiple axially extending rectangular stator slots 101 are evenly distributed on the inner ring surface. The depth of the stator slot 101 is the space shared by the main winding 2 and the monitoring winding 301. The main winding 2 is made of multiple strands of insulated copper wire and is embedded in the stator slot 101 on the side away from the axis. The main winding 2 occupies 60-70% of the depth of the stator slot 101. The monitoring winding assembly 3 includes two or more independently arranged monitoring windings 301. The monitoring windings 301 are symmetrically arranged in the stator slot 101 near the axis, located in the unoccupied space above the main winding 2. The monitoring windings 301 occupy the remaining 30-40% of the top of the stator slot 101. An electromagnetic shielding layer 7 is provided between the main winding 2 and the monitoring winding assembly 3. The electromagnetic shielding layer 7 is a ring-shaped thin sheet structure that fits tightly against the inner wall of the stator slot 101 to reduce electromagnetic interference from the main winding 2 to the monitoring winding 301.

[0032] Second embodiment: In this embodiment, the monitoring winding 301 is arranged in an independent monitoring winding slot 102. The specific structure is as follows: The stator core 1 is a ring structure, and multiple axially extending rectangular stator slots 101 are evenly opened on the inner ring surface. Multiple axially extending monitoring winding slots 102 are evenly opened between the stator slots 101. The main winding 2 is made of multiple strands of insulated copper wire and is embedded in the stator slot 101. The main winding 2 occupies the entire depth of the stator slot 101. The monitoring winding assembly 3 includes two or more independently arranged monitoring windings 301. The monitoring windings 301 are embedded inside the monitoring winding slots 102, symmetrically distributed along the inner ring surface of the stator core 1, and all monitoring windings 301 are located in the same ring surface.

[0033] When using this invention, the motor runs and the rotor rotation generates a changing magnetic field in the air gap. The monitoring winding 301 senses the change in the air gap magnetic field and generates an induced voltage signal. Since the monitoring windings 301 are symmetrically arranged, the voltage signal sensed by each monitoring winding 301 reflects the air gap magnetic field distribution at the corresponding position. The beginning and end of the monitoring windings 301 are connected to the differential amplifier circuit of the voltage detector 4 through multi-strand shielded wires. The differential amplifier circuit amplifies the weak induced voltage signal of the monitoring windings 301 and suppresses common-mode noise. The amplified signal enters the filter circuit of the harmonic analyzer 6. The filter circuit removes high-frequency noise and unwanted harmonic components from the signal and retains the low-frequency signal related to the air gap imbalance. The filtered signal is input to the digital signal processing chip. The digital signal processing chip processes the signal, extracts the spectral characteristics of the signal, analyzes the harmonic components of the air gap magnetic field to determine whether there is an imbalance in the air gap, and compares the analysis result with a preset threshold. If the detected signal exceeds the threshold range, the threshold judge will output an alarm signal or trigger corresponding control measures.

[0034] Although embodiments of the present invention have been shown and described, it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, it will be understood by those skilled in the art that all other embodiments obtained by making various changes, modifications, substitutions and alterations to these embodiments without departing from the principles and spirit of the present invention and without creative effort are within the scope of protection of the present invention.

Claims

1. A motor air gap balance monitoring winding, characterized in that, include: The stator core (1) is provided with a main winding (2) and a monitoring winding assembly (3). The stator core (1) is a ring structure with multiple axially extending rectangular stator slots (101) evenly opened on the inner ring surface. The main winding (2) is made of multiple strands of insulated copper wire and is embedded in the stator slots (101). The monitoring winding assembly (3) includes two or more independently set monitoring windings (301). The monitoring windings (301) are symmetrically distributed along the inner ring surface of the stator core (1) and all monitoring windings (301) are located in the same ring surface. The monitoring windings (301) are electrically connected to voltage detectors (4) at both ends. The output end of the voltage detectors (4) is electrically connected to a threshold detector (5) and a harmonic analyzer (6).

2. The motor air gap balance monitoring winding according to claim 1, characterized in that, The main winding (2) is embedded in the stator slot (101) on the side away from the axis, and the monitoring winding (301) is symmetrically arranged in the stator slot (101) on the side close to the axis, located in the free space above the main winding (2) that is not occupied by the main winding (2).

3. The motor air gap balance monitoring winding according to claim 2, characterized in that, An electromagnetic shielding layer (7) is provided between the main winding (2) and the monitoring winding assembly (3). The electromagnetic shielding layer (7) is an annular thin sheet structure that fits tightly against the inner wall of the stator slot (101).

4. The motor air gap balance monitoring winding according to claim 3, characterized in that, The spatial relationship between the main winding (2) and the monitoring winding (301) is as follows: the main winding (2) occupies 60-70% of the depth of the stator slot (101), and the monitoring winding (301) occupies the top of the remaining 30-40%.

5. The motor air gap balance monitoring winding according to claim 1, characterized in that, Multiple axially extending monitoring winding slots (102) are uniformly opened between the stator slots (101), and the monitoring winding (301) is embedded inside the monitoring winding slots (102).

6. The motor air gap balance monitoring winding according to claim 1, characterized in that, The voltage detector (4) includes a differential amplifier circuit, the input of which is connected to the beginning and end of each monitoring winding (301) via a multi-strand shielded wire.

7. The motor air gap balance monitoring winding according to claim 6, characterized in that, The harmonic analyzer (6) includes a filter circuit and a digital signal processing chip, and the output of the filter circuit is connected in parallel with the threshold detector (5).

8. The motor air gap balance monitoring winding according to claim 7, characterized in that, The monitoring winding (301) is a single continuously wound circular cross-section thin wire with 3-15 turns, and all turns are connected in series. The beginning and end are connected to the insulated wire by welding, and the insulated wire is covered with an insulating sleeve.

Images