Motor process parameter design method for suppressing electromagnetic interference of motor driving system

Abstract

The invention discloses a motor process parameter design method for suppressing electromagnetic interference of a motor driving system. The method comprises the steps of designing the number N of motor bearing balls, designing the number n of parallel winding strands of a single motor stator winding and an enameled wire, and designing the thickness dz of insulating packing paper of the motor stator winding. The motor designed by the method can reduce electromagnetic interference and reduce motor operation faults.

Description

Technical Field

[0001] The invention belongs to the technical field of variable frequency motor design, and relates to a motor process parameter design method for suppressing electromagnetic interference of a motor drive system. Background Art

[0002] Motor drive systems are widely used in rail transit, electric vehicles, aerospace, refrigeration and air conditioning and other fields. The dv / dt and di / dt generated in the PWM inverter switch control process generate electromagnetic interference. With the development of semiconductor switching devices, the switching frequency of the device increases and the range of its electromagnetic interference emission spectrum becomes wider, resulting in serious electromagnetic interference problems on the motor load side. The electromagnetic interference on the output side of the motor drive system forms an interference current loop with the motor load. At the same time, the stator winding current contains a large number of high-order harmonics, which makes the air gap electromagnetic field also generate a large number of harmonics, significantly affecting the amplitude of the motor air gap electromagnetic field. Electromagnetic interference can cause motor vibration and increase the system noise of the variable frequency speed regulation process. Long-term operation causes bearing corrosion and motor insulation failure, accelerates the occurrence of motor failure, and reduces the service life of the motor. In order to avoid the electromagnetic interference generated by the motor drive system from affecting the normal operation of the motor, a motor process parameter design method is needed to effectively reduce the electromagnetic interference of the motor drive system on the motor load side, weaken the motor vibration caused by electromagnetic interference and the corrosion of the bearing by the shaft current, and ensure the safe operation of the motor and drive system in various occasions. Summary of the invention

[0003] The purpose of the present invention is to provide a motor process parameter design method for suppressing electromagnetic interference of a motor drive system. The motor designed by this method can avoid electromagnetic interference and reduce motor operation failures.

[0004] The technical solution adopted by the present invention is a motor process parameter design method for suppressing electromagnetic interference of a motor drive system, including the design of the number N of motor bearing balls, the design of the number n of parallel windings of a single enameled wire of a motor stator winding, the design of the thickness d of the insulating padding paper of the motor stator winding, and the design of the number of parallel windings of the enameled wire of the motor stator winding. z design.

[0005] The present invention is also characterized in that:

[0006] The design process of the number N of motor bearing balls is:

[0007] In order to make the total parasitic capacitance C between the inner raceway of the motor bearing and the outer raceway of the motor bearing B Reduce to C BM Therefore, the upper limit of the number of motor bearing balls N is expressed by the following formula (1):

[0008]

[0009] Among them, εb is the dielectric constant of the bearing raceway lubricant, l b is the bearing raceway width, D b is the diameter of the motor bearing ball, r ib is the inner raceway radius of the bearing, ε a is the dielectric constant of air, d b D is the distance between the motor bearing ball and the bearing raceway. a is the distance between two adjacent motor bearing balls;

[0010] In order to ensure the smooth operation of the motor, the lower limit of the number N of motor bearing balls can be expressed by formula (2):

[0011]

[0012] Among them, α is the safety margin, F r is the radial force on the bearing when the motor is in operation, and Q is the maximum load on each motor bearing ball;

[0013] While ensuring the smooth running performance of the motor, the total parasitic capacitance C between the inner and outer raceways of the bearing B The range of the number of motor bearing balls N can be expressed by formula (3) if the number of motor bearing balls N is reduced by 50%.

[0014]

[0015] Among them, α is the safety margin, F r is the radial force on the bearing when the motor is running, Q is the maximum load that each motor bearing ball can bear, and ε b is the dielectric constant of the bearing raceway lubricant, D b is the diameter of the motor bearing ball, r ib is the inner raceway radius of the bearing, ε a is the dielectric constant of air, d b D is the distance between the motor bearing ball and the bearing raceway. a It is the distance between the motor bearing balls.

[0016] When the number of motor bearing balls N is designed, the parasitic capacitance C of the oil film between the motor bearing balls and the inner and outer raceways is b11 With C b12 It is expressed by formula (4):

[0017]

[0018] Among them, ε b is the dielectric constant of the bearing raceway lubricant, l b is the bearing raceway width, D b is the diameter of the motor bearing ball, db is the distance between the motor bearing ball and the bearing raceway;

[0019] When designing the number of balls N in the motor bearing, the parasitic capacitance C of the air gap between the inner and outer raceways of the bearing is b13 It is expressed by formula (5):

[0020]

[0021] Among them, ε a is the dielectric constant of air, D a is the distance between two adjacent motor bearing balls, D b is the diameter of the motor bearing ball, d b is the distance between the motor bearing ball and the bearing raceway;

[0022] When designing the number of balls N in the motor bearing, the total parasitic capacitance C between the inner and outer raceways of the bearing is B It is expressed by formula (6):

[0023]

[0024] Where N is the number of bearing balls, l b is the bearing raceway width, ε b is the dielectric constant of the bearing raceway lubricant, ε a is the dielectric constant of air, D b is the diameter of the motor bearing ball, D a is the distance between the motor bearing balls, d b It is the distance between the motor bearing ball and the bearing raceway.

[0025] When designing the number of balls N in the motor bearing, the parasitic capacitance C between the inner raceway of the motor bearing and the outer raceway of the motor bearing is BM It is expressed by formula (7):

[0026]

[0027] Among them, ε b is the dielectric constant of the bearing raceway lubricant, l b is the bearing raceway width, D b is the diameter of the motor bearing ball, r ib is the inner raceway radius of the bearing, d b It is the distance between the motor bearing ball and the bearing raceway.

[0028] The design process of the number of parallel winding strands n of a single parallel-wound enameled wire for the motor stator winding is:

[0029] Equivalent radius R of a single stator winding enameled wire w It is expressed by formula (8):

[0030]

[0031] Where n is the number of strands of the stator winding enameled wire wound in parallel, R 2 is the radius of the single-strand enameled wire of the stator winding;

[0032] The equivalent coupling area between a single parallel-wound enameled wire of the stator winding and the side wall and bottom of the stator slot is expressed by formula (9):

[0033]

[0034] Among them, l w is the length of the motor stator, n is the number of strands of the stator winding, R 2 is the radius of the single-strand enameled wire of the stator winding;

[0035] In a single stator slot of a motor, the parasitic capacitance between the motor stator winding and the side wall of the stator slot is expressed by formula (10):

[0036]

[0037] Among them, ε q is the dielectric constant of the enameled layer of the stator winding single-strand enameled wire, l w is the length of the motor stator, M 1 is the number of stator windings at the side wall of the stator slot, n is the number of strands of the stator winding enameled wire wound in parallel, R 2 R is the radius of the stator winding single-strand enameled wire, 1 is the radius of the single-strand enameled wire core of the stator winding;

[0038] In a single stator slot of a motor, the parasitic capacitance between the motor stator winding and the bottom of the stator slot is expressed by formula (11):

[0039]

[0040] Among them, ε q is the dielectric constant of the enameled layer of the stator winding single-strand enameled wire, l w is the length of the motor stator, M 2 is the number of stator windings at the bottom of the stator slot, n is the number of strands of the stator winding enameled wire wound in parallel, R 2 R is the radius of the stator winding single-strand enameled wire, 1 is the radius of the single-strand enameled wire core of the stator winding;

[0041] The total parasitic capacitance C between the motor stator winding and the motor stator WF It is expressed by formula (12):

[0042]

[0043] Among them, ε q is the dielectric constant of the enameled layer of the stator winding single-strand enameled wire, l w is the length of the motor stator, M 1 M is the number of stator windings at the side wall of the stator slot. 2 is the number of stator windings at the bottom of the stator slot, and P is the number of stator slots of the motor;

[0044] The parasitic capacitance between the motor stator winding and the motor stator cannot be greater than C WFM , C WFM It is expressed by formula (13):

[0045]

[0046] Among them, I GB_3MHz is the maximum limit of common mode interference current of the motor system at a frequency of 3MHz, ω 3MHz is the angular frequency of 3MHz, V GB_3MHz L is the maximum limit of common mode interference voltage of the motor system at a frequency of 3MHz. W is the parasitic inductance of the motor stator winding;

[0047] The number of parallel winding strands n of a single parallel winding enameled wire of the motor stator winding should satisfy formula (14):

[0048]

[0049] Among them, R 2 R is the radius of the stator winding single-strand enameled wire, 1 is the radius of the single-strand enameled wire core of the stator winding, ε q is the dielectric constant of the enameled layer of the stator winding single-strand enameled wire, l w is the length of the motor stator, M 1 M is the number of stator windings at the side wall of the stator slot. 2 is the number of stator windings at the bottom of the stator slot, and P is the number of stator slots of the motor.

[0050] Thickness of insulation paper for motor stator winding d z The design process is:

[0051] The parasitic capacitance generated by the insulating paper is expressed by formula (15):

[0052]

[0053] Where P is the number of stator slots in the motor, ε z is the dielectric constant of the insulating paper, l fsis the length of the stator slot side wall, l fd is the width of the stator slot bottom, l w is the length of the motor stator, d z is the thickness of the insulating paper;

[0054] After adding insulating pad paper, the total parasitic capacitance C between the motor stator winding and the motor stator WFz It is expressed by formula (16):

[0055]

[0056] Where P is the number of stator slots in the motor, l fs is the length of the stator slot side wall, l fd is the width of the bottom of the stator slot;

[0057] In order to reduce the parasitic capacitance between the motor stator winding and the motor stator to 50% of the original value, the thickness of the motor stator winding insulation pad is d z It is expressed by formula (17):

[0058]

[0059] The beneficial effect of the present invention is that the design method provided by the present invention can design a method for designing motor process parameters of a motor drive system according to the flow path of high-frequency electromagnetic interference current in the motor body, and by reducing the coupling distance and coupling area between the various components of the motor, the electromagnetic interference in the motor body can be greatly weakened, and the motor vibration and noise due to electromagnetic interference and the rotor bearing corrosion due to shaft current can be prevented, thereby ensuring the reliability and stability of the normal operation of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a schematic diagram of an electromagnetic interference suppression process for designing the number of motor bearing balls in a motor process parameter design method for suppressing electromagnetic interference of a motor drive system according to the present invention;

[0061] Figure 2 It is a schematic diagram of a process for suppressing electromagnetic interference on the side wall of a stator slot by designing the number of parallel windings of a motor stator winding wire in a motor process parameter design method for suppressing electromagnetic interference in a motor drive system according to the present invention;

[0062] Figure 3 It is a schematic diagram of a process for suppressing electromagnetic interference at the bottom of a stator slot by designing the number of parallel windings of a motor stator winding wire in a motor process parameter design method for suppressing electromagnetic interference of a motor drive system according to the present invention;

[0063] Figure 4It is a schematic diagram of an electromagnetic interference suppression process of adding insulating pad paper between a motor stator winding and a stator in a motor process parameter design method for suppressing electromagnetic interference of a motor drive system of the present invention;

[0064] Figure 5 It is a radial schematic diagram of a motor structure in a motor process parameter design method for suppressing electromagnetic interference of a motor drive system according to the present invention;

[0065] Figure 6 It is a schematic diagram of a simulation model of electromagnetic interference of a motor drive system in a motor process parameter design method for suppressing electromagnetic interference of a motor drive system;

[0066] Figure 7 A diagram showing simulation results of an electromagnetic interference suppression process for designing the number of motor bearing balls in a motor process parameter design method for suppressing electromagnetic interference in a motor drive system according to the present invention;

[0067] Figure 8 A simulation result diagram of the electromagnetic interference suppression process designed by the number of parallel windings of the motor stator winding wire in the motor process parameter design method for suppressing the electromagnetic interference of the motor drive system of the present invention;

[0068] Fig. 9 This is a diagram of simulation results of the electromagnetic interference suppression process of adding insulating paper between the stator winding and the stator of the motor in the motor process parameter design method for suppressing the electromagnetic interference of the motor drive system of the present invention.

[0069] In the figure, 1. inner raceway of motor bearing, 2. outer raceway of motor bearing, 3. bearing ball, 4. rotating shaft, 5. side wall of stator slot, 6. single-strand enameled wire core of stator winding, 7. enameled layer of single-strand enameled wire of stator winding, 8. single-strand enameled wire of stator winding, 9. bottom of stator slot, 10. motor stator, 11. insulating pad paper, 12. motor stator winding, 13. motor housing, 14. motor rotor, 15. bearing, 16. bearing raceway. DETAILED DESCRIPTION

[0070] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0071] Example 1

[0072] The method for designing motor process parameters for suppressing electromagnetic interference of a motor drive system of the present invention includes the following preparations before operation: Figure 1 It is a schematic diagram of the electromagnetic interference suppression process for designing the number of motor bearing balls, including a motor bearing inner raceway 1, a bearing outer raceway 2, a motor bearing ball 3, and a rotating shaft 4 which are connected in sequence. Figure 2It is a schematic diagram of the electromagnetic interference suppression process of the stator slot side wall designed with the parallel winding number of the motor stator winding wire, including the stator slot side wall 5, the stator winding single-strand enameled wire core 6, the stator winding single-strand enameled wire enameled layer 7, and the stator winding single parallel-wound enameled wire 8 connected in sequence. Figure 3 It is a schematic diagram of the electromagnetic interference suppression process at the bottom of the stator slot designed with the parallel winding number of the motor stator winding wire, including a stator slot bottom 9, a stator winding single-strand enameled wire core 6, a stator winding single-strand enameled wire enameled layer 7, and a stator winding single parallel-wound enameled wire 8 connected in sequence. Figure 4 It is a schematic diagram of an electromagnetic interference suppression process of adding insulating paper between a motor stator winding and a stator, comprising a motor stator 10, insulating paper 11, a stator winding single-strand enameled wire core 6, and a stator winding single-strand enameled wire enameled layer 7 connected in sequence. Figure 5 It is a radial schematic diagram of the motor structure, which includes a motor stator winding 12, a motor stator 10, a motor housing 13, a motor bearing ball 3, a motor bearing 15, a motor shaft 4, a motor rotor 14, and a bearing raceway 16 which are connected in sequence.

[0073] The method for designing motor process parameters for suppressing electromagnetic interference of a motor drive system of the present invention, the parameter design process is as follows:

[0074] 1) Design of the number N of motor bearing balls 3:

[0075] When the motor is running, there is a potential difference between the motor bearing ball 3 and the inner raceway 1 and the outer raceway 2 of the motor bearing, so that charges are accumulated on the motor bearing ball 3 and the inner and outer raceways, so that the oil film parasitic capacitance between the motor bearing ball 3 and the inner and outer raceways is generated. Therefore, the oil film parasitic capacitance C between the motor bearing ball 3 and the inner and outer raceways is b11 With C b12 It can be expressed by formula (1).

[0076]

[0077] Among them, ε b is the dielectric constant of the bearing raceway lubricant, l b is the width of bearing raceway 16, D b is the diameter of the motor bearing ball 3, d b It is the distance between the motor bearing ball 3 and the bearing raceway 16.

[0078] At the same time, in the air gap between different motor bearing balls 3, there is also a potential difference between the inner and outer raceways of the bearing. As a result, due to the accumulated charges on the inner and outer raceways, the air gap between the inner and outer raceways of the bearing generates parasitic capacitance. Therefore, the parasitic capacitance C of the air gap between the inner and outer raceways of the bearing is b13 It can be expressed by formula (2).

[0079]

[0080] Among them, ε a is the dielectric constant of air, l b is the width of bearing raceway 16, D a is the distance between the motor bearing balls 3 and the motor bearing balls 3, d b D is the distance between the motor bearing ball 3 and the bearing raceway 16. b is the diameter of the motor bearing ball 3.

[0081] Total parasitic capacitance C between inner and outer raceways of bearing B It is composed of the parasitic capacitance between N motor bearing balls 3 and the inner raceway 1 of the motor bearing, the parasitic capacitance between N motor bearing balls 3 and the outer raceway 2 of the motor bearing, and the parasitic capacitance of the air gap between N motor bearing balls 3 and the motor bearing balls 3. Therefore, the total parasitic capacitance between the inner and outer raceways of the bearing is C B It can be expressed by formula (3).

[0082]

[0083] Where N is the number of bearing balls, l b is the width of the bearing raceway 16, ε b is the dielectric constant of the bearing raceway lubricant, ε a is the dielectric constant of air, D b is the diameter of the motor bearing ball 3, D a is the distance between the motor bearing balls 3 and the motor bearing balls 3, d b It is the distance between the motor bearing ball 3 and the bearing raceway 16.

[0084] If the electromagnetic compatibility design of the motor bearing is not considered, in order to ensure the load-bearing capacity of the motor bearing 15, the motor bearing balls 3 are set to be closely placed, and there is no need to consider the parasitic capacitance generated by the air gap between the motor bearing balls 3 and the motor bearing balls 3. At this time, the value of the parasitic capacitance between the inner raceway 1 of the motor bearing and the outer raceway 2 of the motor bearing is the largest, so the parasitic capacitance between the inner raceway 1 of the motor bearing and the outer raceway 2 of the motor bearing can be expressed by formula (4).

[0085]

[0086] Among them, ε b is the dielectric constant of the bearing raceway lubricant, l b is the width of bearing raceway 16, D b is the diameter of the motor bearing ball 3, r ib is the radius of the inner raceway 1 of the motor bearing, d b It is the distance between the motor bearing ball 3 and the bearing raceway 16.

[0087] In order to reduce the total parasitic capacitance C between the inner race 1 and the outer race 2 of the motor bearing to below 50% of C B the upper limit value of the number N of the motor bearing balls 3 can be expressed by formula (5). BM

[0088]

[0089] Among them, ε b is the dielectric constant of the lubricating oil in the bearing raceway, l b is the width of the bearing raceway 16, D b is the diameter of the motor bearing ball 3, r ib is the radius of the inner race 1 of the bearing, ε a is the dielectric constant of air, d b is the distance between the motor bearing ball 3 and the bearing raceway 16, D a is the distance between the motor bearing balls 3.

[0090] The number of balls in the bearing determines the maximum radial load under the operating state of the motor. To ensure the stable operation of the motor, the lower limit value of the number N of the motor bearing balls 3 can be expressed by formula (6).

[0091]

[0092] Among them, α is the safety margin, F r is the radial force on the bearing under the operating state of the motor, and Q is the maximum load that each motor bearing ball 3 can withstand.

[0093] While ensuring the stable operation performance of the motor, reducing the total parasitic capacitance C between the inner and outer raceways of the bearing by 50%, the range of the number N of the motor bearing balls 3 can be expressed by formula (7). B

[0094]

[0095] Among them, α is the safety margin, F r is the radial force on the bearing under the operating state of the motor, Q is the maximum load that each motor bearing ball 3 can withstand, ε b is the dielectric constant of the lubricating oil in the bearing raceway, D b is the diameter of the motor bearing ball 3, r ib is the radius of the inner race 1 of the bearing, ε a is the dielectric constant of air, d b is the distance between the motor bearing ball 3 and the bearing raceway 16, D a is the distance between the motor bearing balls 3.

[0096] Embodiment 2​​

[0097] Design of the number of parallel winding strands n of a single parallel winding enameled wire 8 for the motor stator winding:

[0098] The stator winding single parallel enameled wire 8 is composed of a stator winding single enameled wire core 6 and a stator winding single enameled wire enameled layer 7. In order to avoid the skin effect, the motor stator winding 12 is usually formed by winding multiple stator winding single parallel enameled wires 8 in parallel to ensure the current carrying capacity of the motor stator winding 12. Therefore, the equivalent radius R of the stator winding single parallel enameled wire 8 is w It can be expressed by formula (8).

[0099]

[0100] Where n is the number of strands of the stator winding, R 2 is the radius of the single-strand enameled wire of the stator winding.

[0101] When the motor is running, there is a potential difference between the motor stator winding 12 and the stator slot side wall 5 and the stator slot bottom 9, so that charge is accumulated between the stator winding wire and the stator slot side wall 5 and the stator slot bottom 9, so that parasitic capacitance is generated between the stator winding wire and the stator slot side wall 5 and the stator slot bottom 9. The parasitic capacitance between the inner winding wire and the stator slot side wall 5 and the stator slot bottom 9 can be ignored due to the shielding effect of the outermost winding wire. Therefore, only the capacitance effect of the outermost winding wire on the stator slot side wall 5 and the stator slot bottom 9 is considered. Therefore, the equivalent coupling area between the stator winding single parallel enameled wire and the stator slot side wall 5 and the stator slot bottom 9 can be expressed by formula (9).

[0102]

[0103] Among them, l w is the length of the motor stator 10, n is the number of strands of the stator winding single enameled wire 8, R 2 is the radius of the single-strand enameled wire of the stator winding.

[0104] In a single stator slot of the motor, the parasitic capacitance between the motor stator winding 12 and the stator slot side wall 5 can be expressed by formula (10).

[0105]

[0106] Among them, ε q is the dielectric constant of the enameled layer 7 of the stator winding single-strand enameled wire, l w is the length of the motor stator 10, M 1 is the number of stator windings 12 of the motor at the position of the stator slot side wall 5, n is the number of strands of the stator winding 8 wound in parallel, R 2 R is the radius of the stator winding single-strand enameled wire, 1is the radius of the single-strand enameled wire core 6 of the stator winding.

[0107] In a single stator slot of the motor, the parasitic capacitance between the motor stator winding 12 and the stator slot bottom 9 can be expressed by formula (11):

[0108]

[0109] Among them, ε q is the dielectric constant of the enameled layer 7 of the stator winding single-strand enameled wire, l w is the length of the motor stator 10, M 2 is the number of stator windings 12 of the motor at the bottom 9 of the stator slot, n is the number of strands of the stator winding enameled wire 8 wound in parallel, R 2 R is the radius of the stator winding single-strand enameled wire, 1 is the radius of the single-strand enameled wire core 6 of the stator winding.

[0110] When the motor is running, the total parasitic capacitance between the motor stator winding 12 and the motor stator 10 is the sum of the stator winding wire and the stator slot side wall 5 and the motor stator winding 12 and the stator slot bottom 9, so the total parasitic capacitance C between the motor stator winding 12 and the motor stator 10 is WF It can be expressed by formula (12).

[0111]

[0112] Among them, ε q is the dielectric constant of the enameled layer 7 of the stator winding single-strand enameled wire, l w is the length of the motor stator 10, M 1 is the number of stator windings 12 of the motor at the position of the stator slot side wall 5, M 2 is the number of stator windings 12 of the motor at the bottom 9 of the stator slot, P is the number of stator slots of the motor, n is the number of strands of the stator winding enameled wire 8 wound in parallel, R 2 R is the radius of the stator winding single-strand enameled wire, 1 is the radius of the single-strand enameled wire core 6 of the stator winding.

[0113] When designing the motor, the maximum limit of interference current that meets the electromagnetic compatibility standard is considered. At this time, the parasitic capacitance between the motor stator winding 12 and the motor stator 10 cannot be greater than C WFM , C WFM It can be expressed by formula (13).

[0114]

[0115] Among them, I GB_3MHz is the maximum limit of common mode interference current of the motor system at a frequency of 3MHz, ω 3MHz is the angular frequency of 3MHz, VGB_3MHz L is the maximum limit of common mode interference voltage of the motor system at a frequency of 3MHz. W is the parasitic inductance of the motor stator winding;

[0116] The number of parallel windings of a single enameled wire 8 of the stator winding is reduced to reduce the capacitance effect of the motor stator winding 12 on the motor stator 10. In order to reduce the parasitic capacitance between the motor stator winding 12 and the motor stator 10 to 50% of the original value, the number of parallel windings n of a single enameled wire 8 of the motor stator winding should satisfy formula (14).

[0117]

[0118] Among them, I GB_3MHz It is the maximum limit of common mode interference current of national standard motor system at frequency 3MHz, ω 3MHz is the angular frequency of 3MHz, V GB_3MHz It is the maximum limit of common mode interference voltage of national standard motor system at 3MHz frequency, L W is the parasitic inductance of the motor stator winding 12, R 2 R is the radius of the stator winding single-strand enameled wire, 1 is the radius of the stator winding single-strand enameled wire core 6, ε q is the dielectric constant of the enameled layer 7 of the stator winding single-strand enameled wire, l w is the length of the motor stator 10, M 1 is the number of stator windings 12 of the motor at the position of the stator slot side wall 5, M 2 is the number of the motor stator windings 12 at the bottom 9 of the stator slots, and P is the number of the motor stator slots.

[0119] Example 3

[0120] The thickness of the insulation paper 11 of the motor stator winding is d z Design:

[0121] An insulating paper pad 11 is added between the motor stator winding 12 and the motor stator 10 to hinder the capacitive coupling effect between the motor stator winding 12 and the stator slot side wall 5 and the stator slot bottom 9. When the motor is running, the total parasitic capacitance between the motor stator winding 12 and the motor stator 10 is the sum of the motor stator winding 12 and the stator slot side wall 5 and the stator slot bottom 9. The medium of the parasitic capacitance is composed of the insulating paper pad 11 and the enameled layer 7 of the single-strand enameled wire of the stator winding. The parasitic capacitance generated by the insulating paper pad 11 can be expressed by formula (15).

[0122]

[0123] Where P is the number of stator slots in the motor, ε z is the dielectric constant of the insulating paper 11, lfs is the length of the stator slot side wall 5, l fd is the width of the stator slot bottom 9, l w is the length of the motor stator 10, d z is the thickness of the insulating paper 11.

[0124] Therefore, after adding the insulating pad 11, the total parasitic capacitance C between the motor stator winding 12 and the motor stator 10 is WFz It can be expressed by formula (16).

[0125]

[0126] Where P is the number of stator slots in the motor, l fs is the length of the stator slot side wall 5, l fd is the width of the stator slot bottom 9, I GB_3MHz It is the maximum limit of common mode interference current of national standard motor system at frequency 3MHz, ω 3MHz is the angular frequency of 3MHz, V GB_3MHz It is the maximum limit of common mode interference voltage of national standard motor system at 3MHz frequency, L W is the parasitic inductance of the motor stator winding 12, ε z is the dielectric constant of the insulating paper 11, l w is the length of the motor stator 10.

[0127] An insulating pad 11 is added between the motor stator winding 12 and the motor stator 10 to reduce the capacitive effect of the motor stator winding 12 and the motor stator 10. In order to reduce the parasitic capacitance between the motor stator winding 12 and the motor stator 10 to 50% of the original value, the thickness d of the motor stator winding insulating pad 11 is z It can be expressed by formula (17).

[0128]

[0129] Where P is the number of stator slots in the motor, ε z is the dielectric constant of the insulating paper 11, l w is the length of the motor stator 10, ω 3MHz is the angular frequency of 3MHz, V GB_3MHz It is the maximum limit of common mode interference voltage of national standard motor system at 3MHz frequency, L W is the parasitic inductance of the motor stator winding 12, I GB_3MHz It is the maximum limit of common mode interference current of national standard motor system at 3MHz frequency, l fs is the length of the stator slot side wall 5, l fd is the width of the stator slot bottom 9.

[0130] Example 4

[0131] The motor designed by the motor process parameter design method for suppressing electromagnetic interference of the motor drive system of the present invention is simulated as follows:

[0132] Figure 5 It is a radial schematic diagram of the motor structure, including the motor stator winding 12, the motor stator 10, the motor housing 13, the motor bearing ball 3, the motor bearing 15, the motor shaft 4, the motor rotor 14, and the bearing raceway 16 connected in sequence. There are two main flow paths for the common mode interference current in the motor structure. The first path is that the motor three-phase drive interference current on the motor load side is input from the three phases A, B, and C to the motor stator winding 12, and passes through the total parasitic capacitance C between the motor stator winding 12 and the motor stator 10. WF , flows into the motor stator 10, then flows through the motor housing 13 which is mechanically connected to the motor stator 10, and finally flows into the system reference ground through the motor housing 13. The second path is that the three-phase drive interference current of the motor load side is input from the three phases A, B, and C to the motor stator winding 12, and passes through the total parasitic capacitance C between the motor stator winding 12 and the motor rotor 14. WR , flows into the motor rotor 14, the inner raceway of the bearing is connected to the motor rotor 14, the outer raceway of the bearing is connected to the motor housing 13, and the interference current passes through the parasitic capacitance C between the inner and outer raceways of the bearing 15 B , flows from the motor rotor 14 into the motor housing 13, and finally flows into the system reference ground through the motor housing 13.

[0133] Figure 6 Schematic diagram of electromagnetic interference simulation model of motor drive system in motor process parameter design method for suppressing electromagnetic interference of motor drive system. To simulate the electromagnetic interference on the motor load side of the motor drive system, Figure 5 The physical model of the motor shown is equivalent to a circuit model. The three-phase drive interference current of the motor is connected to the stator winding of each phase of the motor through the input cable. The motor stator winding 12 is equivalent to an impedance network to simulate the electrical characteristics of the motor stator winding 12, including the equivalent resistance R of the motor stator winding 12. WW1 , R WW2 , R WW3 and equivalent inductance L WW1 , L WW2 , L WW3 The equivalent resistance of each phase stator winding is set to 10.96Ω, and the equivalent inductance is set to 13.3μH. The motor stator 10 is connected to the motor housing 13, and the motor housing 13 is connected to the reference ground. The parasitic coupling effect of the motor stator winding 12 on the motor stator 10 is equivalent to the parasitic capacitance C WF1 , C WF2 , C WF3The parasitic coupling effect between the motor stator winding 12 and the motor rotor 14 is equivalent to the parasitic capacitance C WR1 , C WR2 , C WR3 The parasitic coupling effect between the motor stator winding 12 and the motor housing 13 at the outlet position is equivalent to the parasitic capacitance C WS1 , C WS2 , C WS3 The capacitance value is set to 0.12nF, which is relatively small and is considered as the main propagation path of the interference current. The parasitic coupling effect between the inner and outer raceways of bearing 15 is equivalent to the parasitic capacitance C B , set its capacitance value to 24.4nF, and set the bearing equivalent resistance R B is 0.76Ω. According to the CE102 power line conducted emission limit setting of GJB-151B in the standard, the starting frequency of the measurement is required to be 10kHz and the cutoff frequency is 10MHz. The motor drive system adopts 270V DC power distribution, and the DC power supply voltage is set to 270V. According to the requirements of the standard GJB-151B, the two power input lines of the DC power supply provide a 50Ω power side stable load impedance by connecting a linear impedance stabilization network. According to the CE102 of the standard GJB-151B, the inductance of the coil impedance stabilization network is set to 50μH, and the capacitor on the input power side is set to 8μF and connected to the reference ground plane of the system. The capacitor on the side of the device under test is set to 250nF, and the capacitor on the side of the device under test is connected to a 1kΩ and a 50Ω parallel resistor to the reference ground plane of the system. The two power input lines of the DC power supply are connected to the inverter through a linear impedance stabilization network. The inverter part consists of six power switching devices Q1, Q2, Q3, Q4, Q5, and Q6. The PWM square wave signal is used to control its switching state. According to the driving frequency of the motor, the PWM square wave signal frequency is set to 1kHz to achieve the driving of the three-phase motor. Figure 6 The schematic diagram of the electromagnetic interference simulation model of the motor drive system is shown.

[0134] Example 5

[0135] Figure 7 This is a simulation result diagram of the electromagnetic interference suppression process for designing the number of motor bearing balls in the motor process parameter design method for suppressing electromagnetic interference in the motor drive system of the present invention, which simulates the flow path of motor A, B, C three-phase input - motor stator winding 12 - motor rotor 14 - bearing 15 - motor housing 13 - system reference ground. The flow path compares the interference current after the number of motor balls is designed with the interference current before the number of motor balls is designed, and reduces by an average of 15.6BμA in the 10kHz-10MHz frequency band of CE102 of standard GJB-151B.

[0136] Example 6

[0137] Figure 8 This is a simulation result diagram of the electromagnetic interference suppression process designed by the number of parallel windings of the motor stator winding wire in the motor process parameter design method for suppressing electromagnetic interference in the motor drive system of the present invention, which simulates the flow path of motor A, B, C three-phase input - motor stator winding 12 - motor stator 10 - motor housing 13 - system reference ground. The flow path compares the interference current after the stator winding parallel winding number is designed with the interference current before the stator winding parallel winding number is designed, and the average reduction is 11.5dBμA in the 10kHz-10MHz frequency band of CE102 of standard GJB-151B.

[0138] Example 7

[0139] Fig. 9 This is a simulation result diagram of the electromagnetic interference suppression process of adding insulating paper between the stator winding and the stator of the motor in the motor process parameter design method for suppressing the electromagnetic interference of the motor drive system of the present invention. It simulates the flow path of the motor A, B, C three-phase input - motor stator winding 12 - motor stator 10 - motor housing 13 - system reference ground. The flow path compares the interference current after adding the insulating paper with the interference current before adding the insulating paper. The average reduction is 4.3dBμA in the 10kHz-10MHz frequency band of CE102 of standard GJB-151B.

[0140] from Figure 7 , Figure 8 and Fig. 9 It can be seen that the method for designing motor process parameters for suppressing electromagnetic interference of motor drive system proposed in the present invention is simulated, and the results of the comparison of the common-mode electromagnetic interference current inside the motor before and after the motor process parameter design method proposed in the present invention is adopted are obtained. The simulation results show that the proposed method effectively reduces the common-mode electromagnetic interference current of the motor drive system, thereby providing certain technical support for a method for designing motor process parameters for suppressing electromagnetic interference of motor drive system.

Claims

1. A motor process parameter design method for suppressing electromagnetic interference of a motor drive system, characterized in that: The invention comprises the design of the number N of motor bearing balls (3), the design of the number n of winding strands of a single enameled wire (8) wound around the motor stator winding, the thickness d of the insulating pad paper (11) of the motor stator winding, and the design of the number n of winding strands of the enameled wire (8) wound around the motor stator winding. z design.

2. The method for designing motor process parameters for suppressing electromagnetic interference of a motor drive system according to claim 1, characterized in that: The design process of the number N of the motor bearing balls (3) is as follows: In order to make the total parasitic capacitance C between the inner raceway (1) of the motor bearing and the outer raceway (2) of the motor bearing B Reduce to C BM Therefore, the upper limit value of the number N of motor bearing balls (3) is expressed by the following formula (1): Among them, ε b is the dielectric constant of the bearing raceway lubricant, l b is the bearing raceway width, D b is the diameter of the motor bearing ball (3), r ib is the radius of the inner raceway (1) of the bearing, ε a is the dielectric constant of air, d b D is the distance between the motor bearing ball (3) and the bearing raceway (16), a is the distance between two adjacent motor bearing balls (3); In order to ensure the smooth operation of the motor, the lower limit of the number N of the motor bearing balls (3) is expressed by formula (2): Among them, α is the safety margin, F r is the radial force on the bearing when the motor is in operation, and Q is the maximum load on each motor bearing ball (3); While ensuring the smooth running performance of the motor, the total parasitic capacitance C between the inner and outer raceways of the bearing B The range of the number N of motor bearing balls (3) is expressed by formula (3) when the number N is reduced by 50%. Among them, α is the safety margin, F r is the radial force on the bearing when the motor is running, Q is the maximum load that each motor bearing ball (3) can bear, and ε b is the dielectric constant of the bearing raceway lubricant, D b is the diameter of the motor bearing ball (3), r ib is the radius of the inner raceway (1) of the bearing, ε a is the dielectric constant of air, d b D is the distance between the motor bearing ball (3) and the bearing raceway (16), a is the distance between the motor bearing balls (3) and the motor bearing balls (3).

3. The method for designing motor process parameters for suppressing electromagnetic interference of a motor drive system according to claim 2, characterized in that: When the number N of the motor bearing balls (3) is designed, the parasitic capacitance C of the oil film between the motor bearing balls (3) and the inner and outer raceways is b11 With C b12 It is expressed by formula (4): Among them, ε b is the dielectric constant of the bearing raceway lubricant, l b is the width of the bearing raceway (16), D b is the diameter of the motor bearing ball (3), d b is the distance between the motor bearing ball (3) and the bearing raceway (16).

4. The method for designing motor process parameters for suppressing electromagnetic interference of a motor drive system according to claim 3 is characterized in that: When the number N of the motor bearing balls (3) is designed, the parasitic capacitance C of the air gap between the inner and outer raceways of the bearing is b13 It is expressed by formula (5): Among them, ε a is the dielectric constant of air, D a is the distance between two adjacent motor bearing balls (3), l b is the width of the bearing raceway (16), D b is the diameter of the motor bearing ball (3), d b is the distance between the motor bearing ball (3) and the bearing raceway (16).

5. The method for designing motor process parameters for suppressing electromagnetic interference of a motor drive system according to claim 4 is characterized in that: When the number N of the motor bearing balls (3) is designed, the total parasitic capacitance C between the inner and outer raceways of the bearing is B It is expressed by formula (6): Where N is the number of bearing balls, l b is the width of the bearing raceway (16), ε b is the dielectric constant of the bearing raceway lubricant, ε a is the dielectric constant of air, D b is the diameter of the motor bearing ball (3), D a is the distance between the motor bearing balls (3) and the motor bearing balls (3), d b is the distance between the motor bearing ball (3) and the bearing raceway (16).

6. The method for designing motor process parameters for suppressing electromagnetic interference of a motor drive system according to claim 5, characterized in that: When the number N of the motor bearing balls (3) is designed, the parasitic capacitance C between the inner raceway (1) of the motor bearing and the outer raceway (2) of the motor bearing is BM It is expressed by formula (7): Among them, ε b is the dielectric constant of the bearing raceway lubricant, l b is the bearing raceway width, D b is the diameter of the motor bearing ball, r ib is the inner raceway radius of the bearing, d b It is the distance between the motor bearing ball and the bearing raceway.

7. The method for designing motor process parameters for suppressing electromagnetic interference of a motor drive system according to claim 6, characterized in that: The design process of the number of parallel winding strands n of a single parallel winding enameled wire (8) of the motor stator winding is as follows: the equivalent radius R of the single parallel winding enameled wire (8) of the stator winding is: w It is expressed by formula (8): Wherein, n is the number of strands of a single enameled wire (8) wound in parallel in the stator winding, and R2 is the radius of a single enameled wire of the stator winding; The equivalent coupling area between a single parallel-wound enameled wire of the stator winding and the stator slot side wall (5) and the stator slot bottom (9) is expressed by formula (9): Among them, l w is the length of the motor stator (10), n is the number of strands of a single enameled wire (8) wound in parallel in the stator winding, and R2 is the radius of a single enameled wire of the stator winding; In a single stator slot of a motor, the parasitic capacitance between the motor stator winding (12) and the stator slot side wall (5) is expressed by formula (10): Among them, ε q is the dielectric constant of the stator winding single-strand enameled wire enameled layer (7), l w is the length of the motor stator (10), M1 is the number of the motor stator winding (12) at the position of the stator slot side wall (5), n is the number of strands of the stator winding single enameled wire (8) wound in parallel, R2 is the radius of the stator winding single enameled wire, and R1 is the radius of the stator winding single enameled wire core (6); In a single stator slot of a motor, the parasitic capacitance between the motor stator winding (12) and the bottom of the stator slot (9) is expressed by formula (11): Among them, ε q is the dielectric constant of the stator winding single-strand enameled wire enameled layer (7), l w is the length of the motor stator (10), M2 is the number of the motor stator winding (12) at the bottom (9) of the stator slot, n is the number of strands of the stator winding enameled wire (8) wound in parallel, R2 is the radius of the stator winding single enameled wire, and R1 is the radius of the stator winding single enameled wire core (6); The total parasitic capacitance C between the motor stator winding (12) and the motor stator (10) WF It is expressed by formula (12): Among them, ε q is the dielectric constant of the stator winding single-strand enameled wire enameled layer (7), l w is the length of the motor stator (10), M1 is the number of motor stator windings (12) at the position of the stator slot side wall (5), M2 is the number of motor stator windings (12) at the position of the stator slot bottom (9), and P is the number of motor stator slots; The parasitic capacitance between the motor stator winding (12) and the motor stator (10) cannot be greater than C WFM , C WFM It is expressed by formula (13): Among them, I GB_3MHz is the maximum limit of common mode interference current of the motor system at a frequency of 3MHz, ω 3MHz is the angular frequency of 3MHz, V GB_3MHz L is the maximum limit of common mode interference voltage of the motor system at a frequency of 3MHz. W is the parasitic inductance of the motor stator winding; The number of parallel winding strands n of a single parallel winding enameled wire (8) of the motor stator winding should satisfy formula (14): Wherein, R2 is the radius of the single-strand enameled wire of the stator winding, R1 is the radius of the single-strand enameled wire core (6) of the stator winding, ε q is the dielectric constant of the stator winding single-strand enameled wire enameled layer (7), l w is the length of the motor stator (10), M1 is the number of motor stator windings (12) at the position of the stator slot side wall (5), M2 is the number of motor stator windings (12) at the position of the stator slot bottom (9), and P is the number of motor stator slots.

8. The method for designing motor process parameters for suppressing electromagnetic interference of a motor drive system according to claim 7, characterized in that: The thickness d of the insulating pad paper (11) of the motor stator winding is z The design process is: The parasitic capacitance generated by the insulating paper (11) is expressed by formula (15): Where P is the number of stator slots in the motor, ε z is the dielectric constant of the insulating paper (11), l fs is the length of the stator slot side wall (5), l fd is the width of the stator slot bottom (9), l w is the length of the motor stator (10), d z is the thickness of the insulating pad paper (11); After adding the insulating pad paper (11), the total parasitic capacitance C between the motor stator winding (12) and the motor stator (10) is WFz It is expressed by formula (16): Where P is the number of stator slots in the motor, l fs is the length of the stator slot side wall (5), l fd is the width of the stator slot bottom (9); In order to reduce the parasitic capacitance between the motor stator winding (12) and the motor stator (10) to 50% of the original value, the thickness d of the motor stator winding insulation pad (11) is z It is expressed by formula (17):

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