Method for avoiding noise caused by groove matching

Abstract

The invention discloses a method for avoiding noise caused by slot matching, relates to the technical field of asynchronous induction motors, and aims to solve the problem that an asynchronous motor proposed in the background technology does not have slot matching suitable for any capacity due to the diversity of slot matching, the inherent frequency of a stator and the diversity of force waves. In order to avoid the problem that electromagnetic noise caused by slot matching brings huge loss to a motor manufacturer, the invention provides the following scheme: the method comprises the following steps: S1, carrying out electromagnetic design according to parameters of an asynchronous motor, and designing slot types of a stator and a rotor corresponding to the parameters; s2, performing simulation test on force waves in an air gap magnetic field of the motor according to the designed stator and rotor, performing statistical analysis on simulation test results, and determining the strength, order and frequency of radial force waves in an air gap. According to the diversity of the slot matching of the asynchronous motor and the diversity of the inherent frequency and the force wave of the corresponding stator, the appropriate slot matching can be calculated in time, and the motor is prevented from generating noise.

Description

Technical Field

[0001] The invention relates to the technical field of asynchronous induction motors, and in particular to a method for avoiding noise caused by slot matching. Background Art

[0002] A motor is an electromagnetic device that realizes the conversion or transmission of electric energy according to the law of electromagnetic induction. An asynchronous motor is an AC motor that realizes the conversion of electromechanical energy into mechanical energy by the interaction between the rotating magnetic field of the air gap and the induced current of the rotor winding to generate electromagnetic torque. The three-phase asynchronous motor is mainly used as a motor to drive various production machinery, such as fans, pumps, compressors, machine tools, light industry and mining machinery, threshers and crushers in agricultural production, processing machinery in agricultural and sideline products, etc. It has a simple structure, easy manufacturing, low price, reliable operation, strong and durable, high operating efficiency and applicable working characteristics. After the stator winding of the three-phase asynchronous motor is added with a symmetrical voltage, a rotating air gap magnetic field is generated, and the rotor winding conductor cuts the magnetic field to generate an induced potential. Since the rotor winding is in a short-circuit state, a rotor current will be generated. The interaction between the rotor current and the air gap magnetic field generates an electromagnetic torque, thereby driving the rotor to rotate. The speed of the motor must be lower than the synchronous speed of the magnetic field, because only in this way can the rotor conductor induce an electric potential to generate rotor current and electromagnetic torque.

[0003] In the motor, the main magnetic flux enters the air gap radially and generates radial force on the stator and rotor, thereby causing electromagnetic vibration and noise. At the same time, it also generates tangential torque and axial force. Different slot matches generate torque orders and frequencies that are different. Radial vibration easily causes resonance with the motor stator core, generating resonance noise. Most slot match schemes of asynchronous motors will generate radial forces of different orders and frequencies in the air gap, and whether electromagnetic noise will be generated depends on whether the stator core resonates with such radial force. Due to the diversity of slot matches and the diversity of stator natural frequencies and force waves, there is no slot match suitable for any capacity of asynchronous motors. In order to avoid the huge losses to motor manufacturers caused by electromagnetic noise caused by slot match, a calculation method needs to be proposed. Summary of the invention

[0004] The present invention provides a method for avoiding noise caused by slot matching, which solves the problem that there is no slot matching suitable for any capacity due to the diversity of slot matching and the diversity of stator natural frequency and force wave of asynchronous motors, and the electromagnetic noise caused by slot matching causes huge losses to motor manufacturers.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for avoiding noise caused by slot matching, comprising the following steps:

[0007] S1: Perform electromagnetic design according to the parameters of the asynchronous motor and design the slot types of the stator and rotor corresponding to the parameters;

[0008] S2: Conduct simulation tests on the force waves in the air gap magnetic field of the motor based on the designed stator and rotor, and conduct statistical analysis on the simulation test results to determine the intensity, order and frequency of the radial force waves in the air gap;

[0009] S3: Simulate the modes of the stator core, analyze the modes with the same or similar frequencies as the force wave, and determine whether the order of the mode is different from the order of the force wave.

[0010] Preferably, the calculation formula for the stator slot size in step S1 is:

[0011] W=(D*2g*2k*2t) / m

[0012] Where W is the slot width, D is the stator outer diameter, g is the insulation thickness of the winding, k is the heat dissipation gap of the winding, t is the insulation thickness of the winding, and m is the number of slots;

[0013] H=(D*2g*2t) / (2m)h

[0014] Where H is the slot depth and h is the height of the winding;

[0015] m=Z / p

[0016] Among them, m is the number of slots, Z is the number of winding turns, and p is the number of pole pairs;

[0017] K s =(W+H) / (2H)

[0018] Among them, Ks is the groove shape coefficient, W is the groove width, and H is the groove depth;

[0019]

[0020] Where, k = 0, 1, 2..., f1 is the stator operating frequency, and f is the number of rotor slots;

[0021]

[0022] Among them, n is the order of the electromagnetic force wave, K1, K2 = ±1, ±2, ±3...

[0023] Preferably, the simulation method in step S2 is to set up a reference surface in the air gap and analyze the force condition of the reference surface. The radial force wave generated by the main wave magnetic field is:

[0024] P r1 =P0+P1

[0025] Where P0 is the constant part of the radial force, acting on the circumference, causing the stator core to be subjected to compressive stress;

[0026] P1=P0cos(2pθ-2ω1t-2θ0)

[0027] Where p is the pole pair number of the main wave, ω1 is the angular velocity of the main wave, θ0 is the initial phase angle, and P1 is the alternating part of the radial force wave.

[0028] The beneficial effects of the present invention are:

[0029] First, the force waves in the air gap magnetic field are simulated, a reference surface is set up in the air gap, the force on the reference surface is analyzed, and the results are statistically analyzed to determine the intensity, order and frequency of the radial force waves in the air gap. Secondly, the modes of the stator core are simulated, and the modes with the same or similar frequencies as the force waves are analyzed to determine whether the order of the modes is different from the order of the force waves. If they are the same, the solution needs to be redesigned. According to the diversity of slot matches of different asynchronous motors and the corresponding stator natural frequencies and force waves, the appropriate slot match can be calculated in time to avoid noise from the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of the stator and rotor slot structure for a method of avoiding noise caused by slot matching proposed by the present invention.

[0031] Figure 2 A summary diagram of the force frequency and order of the air gap radial force in a method for avoiding noise caused by slot matching proposed by the present invention.

[0032] Figure 3 A stator core modal simulation diagram of a method for avoiding noise caused by slot matching proposed by the present invention. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0034] Example 1, reference Figure 1-3 , a method for avoiding noise caused by slot matching, comprising the following steps:

[0035] S1: Perform electromagnetic design based on the parameters of the asynchronous motor, and design the stator and rotor slot types corresponding to the parameters. The calculation formula for the stator slot size is:

[0036] W=(D*2g*2k*2t) / m

[0037] Where W is the slot width, D is the stator outer diameter, g is the insulation thickness of the winding, k is the heat dissipation gap of the winding, t is the insulation thickness of the winding, and m is the number of slots;

[0038] H=(D*2g*2t) / (2m)h

[0039] Where H is the slot depth and h is the height of the winding;

[0040] m=Z / p

[0041] Among them, m is the number of slots, Z is the number of winding turns, and p is the number of pole pairs;

[0042] K s =(W+H) / (2H)

[0043] Among them, Ks is the groove shape coefficient, W is the groove width, and H is the groove depth;

[0044]

[0045] Where, k = 0, 1, 2..., f1 is the stator operating frequency, and f is the number of rotor slots;

[0046]

[0047] Among them, n is the order of electromagnetic force wave, K1, K2 = ±1, ±2, ±3...;

[0048] S2: Based on the designed stator and rotor, the force wave in the air gap magnetic field of the motor is simulated and tested, and the simulation test results are statistically analyzed to determine the intensity, order and frequency of the radial force wave in the air gap. The simulation method is to set up a reference surface in the air gap and analyze the force condition of the reference surface. The radial force wave generated by the main wave magnetic field is:

[0049] P r1 =P0+P1

[0050] Where P0 is the constant part of the radial force, acting on the circumference, causing the stator core to be subjected to compressive stress;

[0051] P1=P0cos(2pθ-2ω1t-2θ0)

[0052] Where p is the pole pair number of the main wave, ω1 is the angular velocity of the main wave, θ0 is the initial phase angle, and P1 is the alternating part of the radial force wave;

[0053] S3: Simulate the modes of the stator core, analyze the modes with the same or similar frequencies as the force wave, and determine whether the order of the mode is different from the order of the force wave.

[0054] Taking a certain type of motor as an example, the basic parameters of the motor are:

[0055] project 1800kW certain type of propulsion motor Voltage 690V power 1800kW Rated speed 1190r / min Rated efficiency ～95.5％ Rated power factor ～0.87 Bearings Rolling bearings

[0056] Perform electromagnetic design based on the basic parameters of the motor and calculate the corresponding motor stator and rotor slot types, such as Figure 1 As shown;

[0057] Determine the reference surface in the air gap, perform Fourier transform on the force on the reference surface, derive the force frequency and order of the radial force in the air gap, and then use EXCEL to summarize and analyze the data to obtain a summary diagram of the force frequency and order of the radial force in the air gap, such as Figure 2 As shown;

[0058] The results show that there is a 6th order force wave with a frequency of 720Hz in the air gap, so it is necessary to calculate the modal of the stator core to check whether the vibration order of the stator core at the corresponding frequency is consistent;

[0059] After the 3D model of the stator core is established, modal simulation is performed to find the corresponding frequency or adjacent frequency and check them one by one. The simulation results are as follows: Figure 3 As shown;

[0060] According to the simulation results, the natural vibration order of the stator core is 3rd when the frequency is around 720Hz, which is inconsistent with the electromagnetic force order mentioned above and does not produce resonance.

[0061] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0062] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0063] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for avoiding noise caused by slot matching, characterized in that: The following steps are involved: S1: Perform electromagnetic design according to the parameters of the asynchronous motor and design the slot types of the stator and rotor corresponding to the parameters; S2: Conduct simulation tests on the force waves in the air gap magnetic field of the motor based on the designed stator and rotor, and conduct statistical analysis on the simulation test results to determine the intensity, order and frequency of the radial force waves in the air gap; S3: Simulate the modes of the stator core, analyze the modes with the same or similar frequencies as the force wave, and determine whether the order of the mode is different from the order of the force wave.

2. A method for avoiding noise caused by slot matching according to claim 1, characterized in that: The calculation formula of the stator slot size in step S1 is: W=(D*2g*2k*2t) / m Where W is the slot width, D is the stator outer diameter, g is the insulation thickness of the winding, k is the heat dissipation gap of the winding, t is the insulation thickness of the winding, and m is the number of slots; H=(D*2g*2t) / (2m)h Where H is the slot depth and h is the height of the winding; m=Z / p Among them, m is the number of slots, Z is the number of winding turns, and p is the number of pole pairs; K s =(W+H) / (2H) Among them, Ks is the groove shape coefficient, W is the groove width, and H is the groove depth; Where, k = 0, 1, 2..., f1 is the stator operating frequency, and f is the number of rotor slots; Among them, n is the order of the electromagnetic force wave, K1, K2 = ±1, ±2, ±3...

3. A method for avoiding noise caused by slot matching according to claim 1, characterized in that: The simulation method in step S2 is to set up a reference surface in the air gap and analyze the force condition of the reference surface. The radial force wave generated by the main wave magnetic field is: P r1 =P0+P1 Where P0 is the constant part of the radial force, acting on the circumference, causing the stator core to be subjected to compressive stress; P1=P0cos(2pθ-2ω1t-2θ0) Where p is the pole pair number of the main wave, ω1 is the angular velocity of the main wave, θ0 is the initial phase angle, and P1 is the alternating part of the radial force wave.

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