Low-harmonic strong coupling permanent magnet hollow compensated pulse generator

Abstract

The application discloses a low-harmonic strong-coupling permanent-magnet hollow compensation pulse generator, which comprises a stator and a rotor arranged in sequence from outside to inside, and the rotor comprises a cage rotor compensation assembly; the cage rotor compensation assembly comprises two sets of symmetrically distributed cage rotor compensation windings; each set of cage rotor compensation windings comprises a plurality of bars arranged in bar grooves of the rotor; the bars form a plurality of pole number structures, and adjacent pole number structures are arranged at intervals; the bars of each set of cage rotor compensation windings are connected in a mode from both sides to the middle or from the middle to both sides; two bars connected in each group are connected through end rings; and a starting end bar and an ending end bar are connected to form a closed loop. The cage rotor compensation assembly compensation structure specially designed in the application not only has the advantages of a solid squirrel cage structure, high mechanical strength and suitability for high-speed operation, but also has the advantages that a winding type winding can be flexibly designed according to pole pairs of the motor, and the rotor harmonics can be effectively controlled.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pulse generator, and particularly relates to a low-harmonic strong coupling permanent magnet hollow compensation pulse generator. BACKGROUND

[0002] Pulse power technology has extremely important applications in the fields of national defense science and technology and high-tech, and is now increasingly applied to industrial and civil departments, such as electromagnetic launching, ray irradiation, high-power microwave, free electron laser, liquid food treatment and medical treatment, and nanometer materials generated by wire explosion. As a kind of rotating electrical machine, the compensation pulse generator is widely concerned due to its advantages of small size, high power and large energy storage density. The working principle of the compensation pulse generator is to compress the magnetic flux by using a compensation element, so as to reduce the transient inductance and realize large-current discharge. The magnetic flux compression refers to that, in the process of discharge, with the rotation of the electrical machine, the induced current is generated in the armature winding, thereby generating the armature magnetic field. The armature reaction demagnetizes the main magnetic field, and the compensation element cuts the armature magnetic field when following the rotation of the rotor, so that the compensation current is generated in the compensation element. The magnetic field generated by the compensation current compensates the magnetic flux generated by the armature winding, so as to compress the magnetic field in the air gap.

[0003] At present, the commonly used compensation element is a compensation cylinder, a short-circuit compensation winding or a compensation squirrel cage. However, the compensation cylinder is a whole structure, and the eddy current induced in the compensation cylinder by the armature magnetic field is used as the compensation current. The direction of the compensation eddy current in the compensation cylinder is relatively complex, the directions of the compensation eddy currents under different poles are different, and the direction of the compensation eddy current is not easy to control. Therefore, a large harmonic is generated, the harmonic content is uncontrollable, and the eddy current loss is high. As a result, the discharge performance is reduced, and the compensation effect is poor. The short-circuit compensation winding adopts a short-circuit compensation structure, which reduces the eddy current loss in the compensation element. Moreover, the direction of the compensation current can be limited by the short-circuit compensation winding, which improves the discharge performance of the electrical machine in a certain sense. However, the mechanical strength of the winding is not enough, and there is a certain limitation when the electrical machine is running at high speed. Moreover, the long end of the short-circuit compensation winding also affects the response speed of the electrical machine. The compensation squirrel cage eliminates the complex end, has better response speed, and has good mechanical strength, which is suitable for high-speed operation and has small eddy current loss. However, the winding of the compensation squirrel cage is a phase under each pair of poles during operation, that is, the number of phases of the compensation squirrel cage is too large during operation. This also leads to the fact that the direction of the compensation current in the compensation squirrel cage is relatively complex, and the current of each conductor is not the same during operation. Therefore, the harmonic content of the magnetic field generated by the compensation current induced in the compensation squirrel cage is high, and the harmonic content is uncontrollable. This also affects the coupling between the fundamental magnetic field of the stator armature winding and the fundamental magnetic field of the compensation winding, thereby reducing the discharge performance and affecting the compensation effect of the compensation pulse generator. SUMMARY

[0004] Based on the technical problems existing in the background art, the application provides a low-harmonic strong-coupling permanent-magnet hollow compensation pulse generator, which adopts a specially designed cage rotor compensation assembly compensation structure, which has the advantages of a solid squirrel cage structure, high mechanical strength and suitability for high-speed operation, and the advantages of a wound rotor winding that can be flexibly designed according to the pole pair number of the motor to effectively control the rotor harmonics.

[0005] The low-harmonic strong-coupling permanent-magnet hollow compensation pulse generator provided by the application comprises a stator and a rotor arranged in sequence from the outside to the inside, the rotor comprises a cage rotor compensation assembly, the cage rotor compensation assembly comprises two sets of symmetrically distributed cage rotor compensation windings, each set of cage rotor compensation windings comprises a plurality of bars arranged in the bar slots of the rotor, the bars constitute a plurality of pole number structures, and adjacent pole number structures are arranged at intervals, the bars of each set of cage rotor compensation windings are connected in a manner from both sides to the middle or from the middle to both sides, and each set of two connected bars is connected through an end ring, and the starting end bar and the ending end bar are connected to form a closed loop.

[0006] Preferably, the rotor further comprises the permanent magnets located in the cage rotor compensation assembly, and the cage rotor compensation assembly and the permanent magnets are fixed to form the rotor through a second casting layer.

[0007] Preferably, the permanent magnets are placed in a Halbach array.

[0008] Preferably, the pole number of the permanent magnets is the same as the pole number of the rotor.

[0009] Preferably, the second casting layer is a high-molecular polymer non-magnetic material.

[0010] Preferably, the stator comprises symmetrically distributed stator armature windings, the stator armature windings are two-phase decoupling structures, and the stator armature windings are single-layer concentric structures wound by copper strands.

[0011] Preferably, the stator armature windings are fixed to form the stator through a first casting layer.

[0012] Preferably, the first casting layer is a high-molecular polymer non-magnetic material.

[0013] Preferably, the pole number of the stator is the same as the pole number of the rotor.

[0014] Preferably, the stator and the rotor are arranged at intervals to form an air gap.

[0015] The application has the following beneficial technical effects:

[0016] The stator and the rotor of the application both adopt high-molecular polymer non-magnetic material, so that the motor has no iron loss during operation and has better discharge performance; the stator winding can control the magnetic potential harmonic generated by the armature winding during motor operation through winding design, so as to reduce the magnetic potential harmonic generated by the armature winding during motor operation, and the armature winding is designed into two-phase decoupling structure, so that the two phases can be controlled respectively, and the discharge waveform has higher adjustability; the permanent magnet is placed according to the Halbach array structure, so that the magnetic field on one side is enhanced and the magnetic field on the other side is almost zero, and the generated excitation magnetic field is almost a standard sine wave and basically does not contain harmonic, so that the harmonic content during motor operation is also reduced; the cage rotor compensation assembly compensation structure adopts copper bar as the rotor winding, has good mechanical strength, can operate at high speed, and the copper bar is welded according to the specially designed winding scheme through the end ring, the winding scheme of the cage rotor compensation assembly compensation structure is designed according to the AC motor winding theory, which not only has the advantages of solid squirrel cage structure, high mechanical strength and high speed operation, but also has the advantages that the wound winding can be flexibly designed according to the pole pair number of the motor, and the rotor harmonic can be effectively controlled; through the design of the compensation winding, the winding coefficient of the compensation winding magnetic potential harmonic can be controlled, so that the harmonic content during motor operation can be effectively reduced, the coupling between the stator armature winding fundamental magnetic field and the compensation winding fundamental magnetic field is enhanced, the discharge performance of the compensation pulse generator is improved, the pulse current amplitude released during discharge is larger, and the compensation effect is better. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a traditional topology structure of the permanent magnet pulse generator;

[0018] Figure 2 is a topology structure of the low-harmonic strong-coupling permanent magnet hollow compensation pulse generator proposed by the application;

[0019] Figure 3 is the slot number and connection diagram of the stator armature winding of the low-harmonic strong-coupling permanent magnet hollow compensation pulse generator proposed by the application;

[0020] Figure 4 is the slot number and connection diagram of the cage rotor compensation assembly of the low-harmonic strong-coupling permanent magnet hollow compensation pulse generator proposed by the application;

[0021] Figure 5 is the specific magnetizing direction diagram of the permanent magnet of the low-harmonic strong-coupling permanent magnet hollow compensation pulse generator proposed by the application;

[0022] Figure 6 is the air gap magnetic density waveform diagram of the low-harmonic strong-coupling permanent magnet hollow compensation pulse generator proposed by the application under no-load operation;

[0023] Figure 7 is the Fourier analysis result chart of the no-load air-gap flux density of the low-harmonic strong-coupling permanent-magnet hollow compensation pulse generator proposed in the application;

[0024] Figure 8 is the specific pouring chart of the cage rotor compensation assembly structure of the low-harmonic strong-coupling permanent-magnet hollow compensation pulse generator proposed in the application;

[0025] Figure 9 is the circuit principle chart of the two-phase series discharge of the low-harmonic strong-coupling permanent-magnet hollow compensation pulse generator proposed in the application;

[0026] Figure 10 is the circuit principle chart of the two-phase parallel discharge of the low-harmonic strong-coupling permanent-magnet hollow compensation pulse generator proposed in the application;

[0027] Figure 11 is the discharge current comparison between the two-phase series discharge of the low-harmonic strong-coupling permanent-magnet hollow compensation pulse generator proposed in the application and the traditional compensation mode;

[0028] Figure 12 is the discharge current comparison between the two-phase parallel discharge of the low-harmonic strong-coupling permanent-magnet hollow compensation pulse generator proposed in the application and the traditional compensation mode.

[0029] In the figure: 1 is a compensation cylinder, 2 is a compensation squirrel cage, 3 is an air gap, 4 is a stator armature winding, 5 is a permanent magnet, 6 is a first pouring layer, 7 is a second pouring layer, and 8 is a cage rotor compensation assembly. DETAILED DESCRIPTION

[0030] The application will be further described below in combination with specific embodiments.

[0031] As Figure 1As shown, mainly using traditional compensation element compensation cylinder 1 or compensation squirrel cage 2, wherein the compensation cylinder 1 is to use the eddy current induced in the compensation cylinder by the armature magnetic field as the compensation current, thereby compressing the magnetic field to realize large current discharge; but the compensation cylinder is a whole structure, the direction of the compensation eddy current in the compensation cylinder is relatively complex, the direction of the compensation eddy current under different poles is different, and the direction of the compensation eddy current is not easy to control, so that a larger harmonic is generated, and the harmonic content of the magnetic potential generated by the compensation eddy current is also uncontrollable, and the eddy current loss is high, thereby reducing the discharge performance, reducing the amplitude of the pulse current, and the compensation effect is poor. The traditional compensation pulse generator can also use short-circuit compensation winding. The short-circuit compensation winding reduces the eddy current loss in the compensation element, and the short-circuit compensation winding can limit the direction of the compensation current, thereby improving the discharge performance of the motor in a certain sense, but the mechanical strength of the winding is not enough, and there is a certain limitation when the motor runs at high speed, and the long end of the short-circuit compensation winding also affects the response speed of the motor. The compensation squirrel cage 2 is based on the compensation cylinder 1 and omits the complex end, has better response speed, and the compensation squirrel cage has good mechanical strength and is suitable for high-speed operation, and the eddy current loss is small, but the winding of the squirrel cage is a phase under each pair of poles during operation, that is, the number of phases of the compensation squirrel cage during operation is too large, which also causes the direction of the compensation current in the compensation squirrel cage to be relatively complex, and the current of each conductor is different during operation, so that the harmonic content of the magnetic potential generated by the compensation current induced in the compensation squirrel cage is high, and the harmonic content is also uncontrollable, which affects the coupling between the stator armature winding fundamental magnetic field and the compensation winding fundamental magnetic field, thereby reducing the discharge performance, reducing the amplitude of the pulse current, and affecting the compensation effect of the compensation pulse generator.

[0032] Figure 2 For an embodiment of the low-harmonic strong-coupling permanent-magnet hollow compensation pulse generator, the stator and the rotor of the scheme both adopt a hollow structure, so that there is no core loss during operation of the motor, and the motor has better discharge performance; the stator has 48 equidistant slots, and the stator armature winding 4 placed in the slots is a specially designed winding, and the stator armature winding 4 adopts a four-pole, two-phase decoupling structure, which can control the discharge of the two-phase winding respectively, thereby greatly improving the adjustability of the motor discharge waveform; in addition, the stator armature winding 4 adopts a single-layer concentric structure wound by multiple copper strands, which is convenient for winding and has a simple process.

[0033] The slot number and connection diagram of the stator armature winding 7 are as follows Figure 3As shown, the A-phase winding is formed by two sets of coils in parallel, wherein the first set of coils has a first end connection wire drawn from the No. 1 slot, and is wound from the No. 1 slot to the No. 18 slot, and then back to the No. 2 slot; from the No. 2 slot to the No. 17 slot, and then back to the No. 3 slot; from the No. 3 slot to the No. 16 slot, and then back to the No. 4 slot; from the No. 4 slot to the No. 15 slot, and then back to the No. 5 slot; from the No. 5 slot to the No. 14 slot, and then back to the No. 6 slot; from the No. 6 slot to the No. 13 slot, and a last end connection wire is drawn from the No. 13 slot. The first end connection wire of the other set of coils of the A-phase winding is drawn from the No. 25 slot, and is wound from the No. 25 slot to the No. 42 slot, and then back to the No. 26 slot; from the No. 26 slot to the No. 41 slot, and then back to the No. 27 slot; from the No. 27 slot to the No. 40 slot, and then back to the No. 28 slot; from the No. 28 slot to the No. 39 slot, and then back to the No. 29 slot; from the No. 29 slot to the No. 38 slot, and then back to the No. 30 slot; from the No. 30 slot to the No. 37 slot, and a last end connection wire is drawn from the No. 37 slot. The first end connection wires of the two sets of coils are connected, and the last end connection wires are connected, i.e., the two sets of coils are in parallel to form the A-phase winding.

[0034] The B-phase winding is also formed by two sets of coils in parallel, wherein the first set of coils has a first end connection wire drawn from the No. 7 slot, and is wound from the No. 7 slot to the No. 24 slot, and then back to the No. 8 slot; from the No. 8 slot to the No. 23 slot, and then back to the No. 9 slot; from the No. 9 slot to the No. 22 slot, and then back to the No. 10 slot; from the No. 10 slot to the No. 21 slot, and then back to the No. 11 slot; from the No. 11 slot to the No. 20 slot, and then back to the No. 12 slot; from the No. 12 slot to the No. 19 slot, and a last end connection wire is drawn from the No. 19 slot. The first end connection wire of the other set of coils of the B-phase winding is drawn from the No. 31 slot, and is wound from the No. 31 slot to the No. 48 slot, and then back to the No. 32 slot; from the No. 32 slot to the No. 47 slot, and then back to the No. 33 slot; from the No. 33 slot to the No. 46 slot, and then back to the No. 34 slot; from the No. 34 slot to the No. 45 slot, and then back to the No. 35 slot; from the No. 35 slot to the No. 44 slot, and then back to the No. 36 slot; from the No. 36 slot to the No. 43 slot, and a last end connection wire is drawn from the No. 43 slot. The first end connection wires of the two sets of coils are connected, and the last end connection wires are connected, i.e., the two sets of coils are in parallel to form the B-phase winding. The axis of the A-phase winding and the axis of the B-phase winding are different by 90° electric angle, i.e., the two-phase windings are decoupled from each other, and the two phases can be controlled for discharge respectively, and the adjustability of the waveform is high.

[0035] The stator is formed by pouring a first pouring layer of high-molecular polymer non-magnetic material on the stator armature winding 4 and fixed on the motor casing.

[0036] According to the winding theory of the alternating current motor, the magnetic potential harmonic is analyzed, and considering the actual situation of the winding, the conductor is taken as a basic unit, the magnetic potential slot vector of the conductor under the ν-pole can be obtained according to formula (1), and the resultant vector of the Z slot vectors under the ν-pole can be obtained according to formula (2).

[0037]

[0038]

[0039] In the formula, M is slot number, Z is total conductor number in winding, and a is slot pitch angle. In order to calculate, the real part and the imaginary part in formula (2) can be expressed as x ν and y ν respectively, that is, formula (3), then the resultant vector of Z slot vectors under p pole pair can be further expressed as formula (4), and the winding distribution coefficient under p pole pair can be calculated by formula (5).

[0040]

[0041] F ν = x ν -jy ν (4)

[0042]

[0043] When conductor is taken as basic unit, winding short pitch coefficient K yν is meaningless, and its value is 1, then the winding coefficient under p pole pair is equal to its distribution coefficient, that is, formula (6), and the harmonic amplitude percentage can be calculated by formula (7).

[0044] K wν = K yν · K pν = K pν (6)

[0045]

[0046] In the formula, p is pole pair number, K wp is winding coefficient under p pole pair. From the above, the magnetic potential harmonic analysis result of stator armature winding is shown in Table 1.

[0047] Table 1 Magnetic potential harmonic analysis result of stator armature winding

[0048] pole pairs winding factor magnetic potential harmonic amplitude percentage (%) 4 0.9029 100.00 12 0.3080 11.3694 20 0.1936 4.2883 28 0.1485 2.3504 36 0.1276 1.5698 44 0.1189 1.1968 52 0.1276 1.0127 60 0.1485 0.9419 68 0.1936 0.9678 76 0.3080 1.1285 84 0.1936 1.6242 92 0.9029 4.3478 100 0.9029 4.0000

[0049] From Table 1, it can be seen that the winding coefficient of fundamental wave is larger, which indicates that the utilization rate of winding fundamental wave is large, although there are 3rd, 5th harmonic waves, and 23rd, 25th tooth harmonic waves, but they can be eliminated through the design of compensation structure 8 of cage rotor compensation assembly and the design of excitation magnetic field of permanent magnet 11.

[0050] For the design of rotor, for example Figure 2As shown, the rotor is equidistantly opened with 64 bar slots, the cage rotor compensation assembly compensation structure 8 has 48 bars, the bar has good mechanical strength, and the end connection is also relatively simple, has good dynamic response characteristics, and the cage rotor compensation assembly compensation structure 8 is specially designed, which can control the harmonic content generated by the cage rotor compensation assembly compensation structure 8 during the operation of the motor, so that it generates less magnetic potential harmonic during the operation of the motor. Therefore, the coupling between the stator armature winding fundamental magnetic field and the compensation winding fundamental magnetic field is strengthened, the harmonic loss is reduced, the discharge performance of the compensation pulse generator is improved, the pulse current amplitude released during discharge is larger, and the compensation effect is better. The cage rotor compensation assembly compensation structure not only takes into account the advantages of high mechanical strength of the squirrel cage, but also has the advantage that the wound winding can be flexibly designed according to the pole pair number of the motor.

[0051] The specific design process is as follows: when the rotor is equidistantly opened with 32 slots, the cage rotor compensation assembly has 24 bars, and the specific slot numbers are 1, 2, 3, 4, 5, 6, -9, -10, -11, -12, -13, -14; 17, 18, 19, 20, 21, 22, -25, -26, -27, -28, -29, -30. At this time, according to the analysis of the winding theory of the alternating current motor, the rotor magnetic potential harmonic analysis results are shown in the following table 2.

[0052] Table 2 Magnetic potential harmonic analysis results of rotor 24-slot compensation winding structure

[0053] pole pairs winding factor magnetic potential harmonic amplitude percentage (%) 4 0.7893 100.00 12 0.1148 4.8484 20 0.0767 1.9438 28 0.1507 2.8416 36 0.1507 2.2101 44 0.0767 0.8835 52 0.1148 1.1189 60 0.7893 6.6667 68 0.7893 5.8824 76 0.1148 0.7655 84 0.0767 0.4628 92 0.1507 0.8648 100 0.1507 0.7956 108 0.0767 0.3600 116 0.1148 0.5019 124 0.7893 3.2258 132 0.7893 3.0303

[0054] As can be seen from table 2, when the rotor adopts 32 slots and the cage rotor compensation assembly bar occupies 24 slots, the 3rd and 5th harmonic contents are small, and the 23rd and 25th tooth harmonic magnetic potential contents generated by the stator armature winding are very low, which can reduce the coupling degree between the stator armature winding harmonic magnetic field and the compensation winding harmonic magnetic field. However, the 15th and 17th tooth harmonic contents of the rotor winding are as high as 6.6667% and 5.8824%, respectively. Although the 15th and 17th tooth harmonics of the rotor winding also have low coupling strength with the corresponding magnetic potential harmonics of the stator armature winding, the proportion of the magnetic potential harmonic amplitude generated by the rotor winding is still relatively high. In order to improve the discharge performance, improvement is needed. Increasing the number of slots per pole per phase can suppress harmonics, and in a certain sense, it also improves the compensation effect. Therefore, when the rotor is equidistantly opened with 64 slots, the design of different slot numbers is compared, and the harmonic analysis comparison results of 36 slots, 48 slots and 60 slots are listed. The specific slot numbers are:

[0055] (1) 36 slots: 1, 2, 3, 4, 5, 6, 7, 8, 9, -17, -18, -19, -20, -21, -22, -23, -24, -25; 33, 34, 35, 36, 37, 38, 39, 40, 41, -49, -50, -51, -52, -53, -54, -55, -56, -57.

[0056] (2) 48 slots: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, -17, -18, -19, -20, -21, -22, -23, -24, -25, -26, -27, -28; 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, -49, -50, -51, -52, -53, -54, -55, -56, -57, -58, -59, -60.

[0057] (3) 52 slots: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, -17, -18, -19, -20, -21, -22, -23, -24, -25, -26, -27, -28, -29, -30, -31; 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, -49, -50, -51, -52, -53, -54, -55, -56, -57, -58, -59, -60, -61, -62, -63.

[0058] The results of the harmonic analysis comparison of the three cases are shown in Table 3.

[0059] Table 3 Magnetic potential harmonic analysis results of different slot number compensation winding structures of the rotor

[0060]

[0061] As can be seen from Table 3, after the rotor is replaced with 64 slots, the content of rotor tooth harmonics is obviously reduced. Moreover, it can also be seen that, with the decrease of slot number, the fundamental winding coefficient increases, that is, the fundamental utilization rate is high. As can be seen from the magnetic potential harmonic amplitude percentage, the 3rd and 5th harmonic contents are high when the 36 and 60 slot structure is designed, and the effect is not ideal, while the harmonic content of the 48 slot is less. Moreover, considering that a large current will flow through the special cage compensation winding when the compensation pulse generator discharges, if the slot number occupied by the bar is too small, the electromagnetic force borne by each bar on average is large, which has the risk of bending deformation, and if the slot number is too large, it will lead to too low winding coefficient, that is, too low fundamental utilization rate, therefore, the 48 slot structure is selected. In addition to the fact that the 3rd and 5th harmonic contents of the 48 slot structure are small, as can be seen from Table 3, the 23rd and 25th harmonic contents of the compensation winding coupled with the 23rd and 25th tooth harmonic magnetic motive force generated by the stator armature winding are very low, so the coupling strength between the stator armature winding harmonic magnetic field and the compensation winding harmonic magnetic field is greatly reduced, thereby effectively enhancing the coupling between the stator armature winding fundamental magnetic field and the compensation winding fundamental magnetic field, and further improving the discharge performance of the compensation pulse generator, the pulse current amplitude released during discharge is larger, and the compensation effect is better.

[0062] In principle, the slot number per pole per phase can also be continuously increased to reduce the magnetic potential harmonics generated by the rotor winding, but the corresponding cost will also increase, more importantly, under the condition that the motor size is the same, if the slot number is too large, it means that the bar is thin, which will weaken the mechanical properties of the cage rotor compensation assembly compensation structure, and the cage rotor compensation assembly is more likely to bend and deform when a large compensation current flows through it. Therefore, considering comprehensively, and after calculation and simulation verification, when the cage rotor compensation assembly compensation structure adopts Figure 4 slots, it has good performance, Figure 4 The specific slot number and connection diagram of the cage rotor compensation assembly are shown in Figs. 6 and 7. According to the four-pole winding, two sets of independent compensation windings are designed to avoid circulating current in the cage rotor compensation assembly, and the copper bars are sequentially welded according to the specially designed winding scheme by using end rings.

[0063] Wherein the first set of compensation winding is connected together by the end ring welded at the end of the bar in No.1 slot and the end of the bar in No.28 slot, the first end of the bar in No.28 slot is connected together with the first end of the bar in No.2 slot by the end ring welded, then the end of the bar in No.2 slot is connected together with the end of the bar in No.27 slot by the end ring welded, the first end of the bar in No.27 slot is connected together with the first end of the bar in No.3 slot by the end ring welded, then the end of the bar in No.3 slot is connected together with the end of the bar in No.26 slot by the end ring welded, the first end of the bar in No.26 slot is connected together with the first end of the bar in No.4 slot by the end ring welded, then the end of the bar in No.4 slot is connected together with the end of the bar in No.25 slot by the end ring welded, the first end of the bar in No.25 slot is connected together with the first end of the bar in No.5 slot by the end ring welded, then the end of the bar in No.5 slot is connected together with the end of the bar in No.24 slot by the end ring welded, the first end of the bar in No.24 slot is connected together with the first end of the bar in No.6 slot by the end ring welded, then the end of the bar in No.6 slot is connected together with the end of the bar in No.23 slot by the end ring welded, the first end of the bar in No.23 slot is connected together with the first end of the bar in No.7 slot by the end ring welded, then the end of the bar in No.7 slot is connected together with the end of the bar in No.22 slot by the end ring welded, the first end of the bar in No.22 slot is connected together with the first end of the bar in No.8 slot by the end ring welded, then the end of the bar in No.8 slot is connected together with the end of the bar in No.21 slot by the end ring welded, the first end of the bar in No.21 slot is connected together with the first end of the bar in No.9 slot by the end ring welded, then the end of the bar in No.9 slot is connected together with the end of the bar in No.20 slot by the end ring welded, the first end of the bar in No.20 slot is connected together with the first end of the bar in No.10 slot by the end ring welded, then the end of the bar in No.10 slot is connected together with the end of the bar in No.19 slot by the end ring welded, the first end of the bar in No.19 slot is connected together with the first end of the bar in No.11 slot by the end ring welded, then the end of the bar in No.11 slot is connected together with the end of the bar in No.18 slot by the end ring welded, the first end of the bar in No.18 slot is connected together with the first end of the bar in No.12 slot by the end ring welded, then the end of the bar in No.12 slot is connected together with the end of the bar in No.17 slot by the end ring welded, the first end of the bar in No.17 slot is connected together with the first end of the bar in No.1 slot by the end ring welded, forming a closed loop, wherein No.13, 14, 15, 16, 19, 30, 31, 32 are empty slots.

[0064] Another set of winding compensation winding by 33 slot end of the bar through the welded end ring and 60 slot end of the bar connected together, 60 slot end of the bar first again through the welded end ring and 34 slot end of the bar first end connected together; again by 34 slot end of the bar through the welded end ring and 59 slot end of the bar connected together, 59 slot end of the bar first again through the welded end ring and 35 slot end of the bar first end connected together; again by 35 slot end of the bar through the welded end ring and 58 slot end of the bar connected together, 58 slot end of the bar first again through the welded end ring and 36 slot end of the bar first end connected together; again by 36 slot end of the bar through the welded end ring and 57 slot end of the bar connected together, 57 slot end of the bar first again through the welded end ring and 37 slot end of the bar first end connected together; again by 37 slot end of the bar through the welded end ring and 56 slot end of the bar connected together, 56 slot end of the bar first again through the welded end ring and 38 slot end of the bar first end connected together; again by 38 slot end of the bar through the welded end ring and 55 slot end of the bar connected together, 55 slot end of the bar first again through the welded end ring and 39 slot end of the bar first end connected together; again by 39 slot end of the bar through the welded end ring and 54 slot end of the bar connected together, 54 slot end of the bar first again through the welded end ring and 40 slot end of the bar first end connected together; again by 40 slot end of the bar through the welded end ring and 53 slot end of the bar connected together, 53 slot end of the bar first again through the welded end ring and 41 slot end of the bar first end connected together; again by 41 slot end of the bar through the welded end ring and 52 slot end of the bar connected together, 52 slot end of the bar first again through the welded end ring and 42 slot end of the bar first end connected together; again by 42 slot end of the bar through the welded end ring and 51 slot end of the bar connected together, 51 slot end of the bar first again through the welded end ring and 43 slot end of the bar first end connected together; again by 43 slot end of the bar through the welded end ring and 50 slot end of the bar connected together, 50 slot end of the bar first again through the welded end ring and 44 slot end of the bar first end connected together; again by 44 slot end of the bar through the welded end ring and 49 slot end of the bar connected together, 49 slot end of the bar first again through the welded end ring and 33 slot end of the bar first end connected together, forming a closed loop, wherein 45, 46, 47, 48, 61, 62, 63, 64 are empty slots. Two sets of compensation winding together constitute a cage rotor compensation assembly compensation structure.

[0065] Therefore, by combining the design of the stator armature winding 4 and the squirrel-cage rotor compensation assembly 8, the magnetomotive force harmonics generated by the stator armature winding and the squirrel-cage rotor compensation assembly in the air gap 10 during motor operation can be effectively reduced, thereby strengthening the coupling between the fundamental magnetic field of the stator armature winding and the fundamental magnetic field of the compensation winding, and improving the discharge performance of the compensation pulse generator. In addition, the permanent magnet 11 adopts a Halbach array and is also designed as a four-pole structure. The excitation magnetic field is basically a standard sine wave, so there are almost no harmonics in the excitation magnetic field. According to the formula (8) for harmonic electromotive force under poles:

[0066]

[0067] In the formula: f ν ν is the harmonic frequency of the pole pair, N is the total number of turns in series in the winding, and φ ν Let ν be the magnetic flux of the polar harmonic magnetic field.

[0068] As can be seen from the above, if the excitation magnetic field does not contain harmonics of the corresponding order or contains very few harmonics of the corresponding order, then the voltage harmonics of the corresponding order actually generated by the winding will not exist or will be very few. Therefore, the present invention can effectively reduce the harmonics generated during motor operation by designing the stator armature winding 4, the squirrel-cage rotor compensation component 8, and the Halebec permanent magnet 5, enhance the coupling between the fundamental magnetic field of the stator armature winding and the fundamental magnetic field of the compensation winding, improve the discharge performance of the compensation pulse generator, and release a larger pulse current amplitude during discharge, thus having a better compensation effect.

[0069] The specific settings of permanent magnet 5 are as follows, such as Figure 2 As shown, a Halbach array was used, consisting of a total of 24 permanent magnets. The Halbach array can enhance the magnetic field on one side and cancel the magnetic field on the other side to near zero, so the magnetization direction of the permanent magnets is particularly important. The spacing angle between the magnetization directions of adjacent permanent magnets is calculated by (9).

[0070]

[0071] In the formula, p is the number of pole pairs, p = 2, and n is the number of permanent magnets per pole, n = 6.

[0072] This allows for the setting of the magnetization direction of the Halback array, such as... Figure 5 The diagram shows the specific magnetization direction of the Halback array permanent magnets. The air gap magnetic flux density waveform under no-load conditions was also simulated, as shown below. Figure 6 As shown, and for Figure 6 Fourier analysis was performed on the unloaded air gap magnetic flux density waveform, and the results are as follows: Figure 7The air-gap flux waveform of no-load operation is close to a standard sine wave, and there is no harmonic content in the Fourier analysis result, which is consistent with the theoretical analysis.

[0073] Meanwhile, in order to strengthen the mechanical strength of the rotor and fix the permanent magnet 5, the cage rotor compensation assembly 8 is placed on the surface of the permanent magnet 5, and the relative positions of the two are as shown in Figure 2 It is worth noting that the axis of the compensation winding coincides with the axis of the N-pole of the permanent magnet. After fixing the relative positions of the cage rotor compensation assembly 8 and the permanent magnet 5, the entire rotor is poured with a second pouring layer 7 of high polymer polymerization non-magnetic material to form the rotor, and the end of the cage rotor compensation assembly is also poured together. This design can make the rotor have better mechanical properties during high-speed operation of the motor. As shown in Figure 8 The specific pouring diagram of the cage rotor compensation assembly 8 in the high polymer polymerization non-magnetic material is shown inThe high polymer polymerization non-magnetic material (such as epoxy resin) has the advantages of high temperature resistance and high mechanical strength, and therefore can fix the cage rotor compensation assembly 8 and the permanent magnet 5 well after pouring, and can also protect the cage rotor compensation assembly 8 and the permanent magnet 5 well under high-speed operation, and can also enhance the mechanical strength of the rotor, so that the rotor has better mechanical properties. Moreover, the non-magnetic material will not increase the effective air gap length of the motor, and will not reduce the coupling strength between the stator armature winding magnetic field and the compensation winding magnetic field.

[0074] In order to verify the advantages of the low-harmonic strong-coupling permanent magnet hollow compensation pulse generator proposed in the present application, which can reduce the high harmonic content of the air-gap magnetic field in the discharge process of the traditional pulse generator and enhance the coupling between the fundamental magnetic field of the stator armature winding and the fundamental magnetic field of the compensation winding, the simulation is carried out according to Figure 1 and Figure 2 The discharge performance of the compensation cylinder compensation, the squirrel cage compensation and the cage rotor compensation assembly of the present application is compared. Because the two-phase winding of the armature winding is decoupled, the two phases can be discharged respectively, such as two-phase series discharge and two-phase parallel discharge. In order to verify the advantages of the pulse generator of the present application proposed in the present application, uncontrolled devices diodes are selected for discharge, and the principle diagrams of two-phase series discharge and two-phase parallel discharge are respectively as shown in Figure 9 and Figure 10

[0075] At 7500 rpm, the discharge is carried out on a 10 mΩ resistance load, and the discharge performance of two-phase series discharge and two-phase parallel discharge of the compensation cylinder compensation, the squirrel cage compensation and the cage rotor compensation assembly compensation is compared. The discharge waveform is as shown in Figure 11 and Figure 12As shown in the figure, it can be clearly seen that the cage rotor compensation assembly has better discharge performance, the peak value of the released pulse current is higher, and thus has better compensation effect. When discharging in two-phase series, the peak value of the pulse current when the compensation cylinder is compensated is 52.98kA, the peak value of the pulse current when the squirrel cage is compensated is 51.28kA, and the peak value of the pulse current when the cage rotor compensation assembly is compensated is 73.30kA. The peak value of the pulse current when the cage rotor compensation assembly is compensated is increased by 38.35% compared with the peak value of the pulse current when the compensation cylinder is compensated, and is increased by 42.94% compared with the peak value of the pulse current when the squirrel cage is compensated. When discharging in two-phase parallel, the peak values of the two pulse currents when the compensation cylinder is compensated are 39.00kA and 38.29kA respectively, the peak values of the two pulse currents when the squirrel cage is compensated are 38.31kA and 37.05kA respectively, and the peak values of the two pulse currents when the cage rotor compensation assembly is compensated are 46.54kA and 42.98kA respectively. The peak values of the two pulse currents when the cage rotor compensation assembly is compensated are increased by 19.33% and 12.25% respectively compared with the peak values of the two pulse currents when the compensation cylinder is compensated, and are increased by 21.48% and 16.01% respectively compared with the peak values of the two pulse currents when the squirrel cage is compensated. Through simulation verification, it can be seen that the peak value of the pulse current of the cage rotor compensation assembly is higher, and the improvement compared with the traditional compensation element is significant, and the compensation effect is better.

[0076] At the same time, the air gap magnetic flux of the air gap magnetic field at the maximum pulse current peak value time of two-phase series discharge and two-phase parallel discharge is analyzed. In order to facilitate comparison, the air gap flux fundamental wave of the compensation cylinder compensation, the squirrel cage compensation and the cage rotor compensation assembly compensation is compared, and the results are shown in Table 4.

[0077] Table 4 Comparison results of air gap flux fundamental wave

[0078]

[0079] It can also be seen from Table 4 that, whether it is two-phase series discharge or two-phase parallel discharge, the air gap flux fundamental wave amplitude in the air gap magnetic field at the maximum pulse current peak value time is the largest when the cage rotor compensation assembly is compensated, so the coupling degree between the stator armature winding fundamental wave magnetic field and the compensation winding fundamental wave magnetic field is high, and the compensation effect is better. Therefore, through the above simulation verification, the benefits of the present application are well confirmed, and it is verified that the low harmonic strong coupling permanent magnet hollow compensation pulse generator proposed in the present application can control the winding coefficient of the compensation winding magnetic potential by designing the compensation winding, thereby effectively reducing the harmonic content during motor operation, and cooperating with the design of the stator armature winding, the purpose of reducing the harmonic content generated during motor operation can be achieved, the coupling between the stator armature winding fundamental wave magnetic field and the compensation winding fundamental wave magnetic field is enhanced, and the discharge performance of the compensation pulse generator is improved, so the compensation effect is better.

Claims

1. A low-harmonic strongly coupled permanent-magnet air-cored compensated pulse generator, characterized in that, The motor comprises a stator and a rotor arranged from outside to inside, the rotor comprises a cage rotor compensation assembly (8), the cage rotor compensation assembly (8) comprises two sets of symmetrically distributed cage rotor compensation windings, each set of the cage rotor compensation windings comprises a plurality of bars arranged in bar slots of the rotor, the bars constitute a plurality of pole number structures, and adjacent pole number structures are arranged at intervals, the bars of each set of the cage rotor compensation windings are connected from both sides to the middle or from the middle to both sides, each set of two connected bars are connected through segmented end rings, and a starting end bar and an ending end bar are connected to form a closed loop. Wherein, both sides refer to the positions of the bars of each set of the cage rotor compensation windings numbered in a circumferential order and located at both ends; the middle refers to the position of the bars of each set of the cage rotor compensation windings numbered in a circumferential order and located in the middle.

2. The low harmonic strong-coupled, permanent-magnet, hollow-compensated, pulse generator of claim 1, wherein, The rotor further comprises a permanent magnet (5) located in the cage rotor compensation assembly (8), and the cage rotor compensation assembly (8) and the permanent magnet (5) are fixed to form the rotor through a second casting layer (7).

3. The low harmonic strong-coupled, permanent magnet, hollow- compensated, pulse generator of claim 2, wherein, The permanent magnet (5) is arranged in a Halbach array.

4. The low harmonic strong-coupled, permanent magnet, hollow- compensated, pulse generator of claim 2, wherein, The pole number of the permanent magnet (5) is the same as that of the rotor.

5. The low harmonic strong-coupled, permanent magnet, hollow- compensated, pulse generator of claim 2, wherein, The second casting layer (7) is a high-molecular polymer non-magnetic material.

6. The low harmonic strong-coupled, permanent magnet, hollow- compensated, pulse generator of claim 1, wherein, The stator comprises symmetrically distributed stator armature windings (4), the stator armature windings (4) are two-phase decoupling structures, and are single-layer concentric structures wound by copper strands.

7. The low harmonic strong-coupled, permanent magnet, hollow- compensated, pulse generator of claim 6, wherein, The stator armature windings (4) are fixed to form the stator through a first casting layer (6).

8. The low harmonic strong-coupled, permanent magnet, hollow- compensated, pulse generator of claim 7, wherein, The first casting layer (6) is a high-molecular polymer non-magnetic material.

9. The low harmonic strong-coupled, permanent magnet, hollow- compensated, pulse generator of claim 1, wherein, The pole number of the stator is the same as that of the rotor.

10. The low harmonic strong-coupled homopolar compensating pulse generator of claim 1, wherein, The stator and the rotor are arranged at intervals to form an air gap (3).

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