Magnetic pole conversion type brushless rotary alternating current voltage regulator and voltage regulating method thereof

Abstract

The invention discloses a magnetic pole conversion type brushless rotary alternating current voltage regulator which comprises a stator, a rotor and a rotating shaft, a rotor mounting groove is formed in the stator, the rotor is rotatably mounted in the rotor mounting groove through the rotating shaft, and multiple groups of winding grooves I are uniformly formed in one side, close to the rotor, of the stator; a plurality of second winding grooves are evenly formed in the side, close to the stator, of the rotor, a primary winding is arranged on the side, away from the rotor, of the first winding grooves and is of a two-pole structure adopting equal-element lap windings, and a secondary winding is arranged on the side, close to the rotor, of the first winding grooves and is of a four-pole structure adopting equal-element lap windings. The plurality of groups of winding slots II are provided with conversion windings, each conversion winding is a single-phase winding closed loop formed by connecting three sections of windings end to end in series, and the slot numbers of adjacent intervals among the three sections of windings are the same. An electric brush of a traditional voltage regulator is omitted, the problems that the electric brush is low in reliability and the output power is limited are solved, and the service life of the alternating current voltage regulator is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of AC voltage regulators, and in particular to a magnetic pole switching type brushless rotary AC voltage regulator and a voltage regulating method thereof. Background Art

[0002] AC voltage regulators are widely used in many fields such as on-load voltage regulation of power grids, transportation, communications, education and scientific research, medical equipment, etc. At present, the commonly used AC voltage regulators mainly include inductive voltage regulators such as autocoupler voltage regulators and shifting coil voltage regulators. With the development of power electronics technology, power electronic voltage regulators such as thyristor voltage regulators and digital voltage regulators have emerged.

[0003] Most of the commonly used inductive voltage regulators currently use contacts and brushes to draw out the output voltage, but the loss on the brushes will reduce the efficiency of the voltage regulator output, and in situations where high power output is required, there is a risk of the brushes burning out, which reduces the reliability of the voltage regulator, so the output power will be limited by the brushes. In addition, the brushes will also wear out when the AC voltage regulator is working, which will affect the service life and the maintenance cost is high. In addition, due to the presence of contacts and brushes, safety hazards are more likely to occur during high-power voltage regulation. In addition, traditional inductive voltage regulators also have problems such as poor output waveform and high harmonic content.

[0004] The power electronic voltage regulator eliminates the need for brushes, which can solve the problems of poor output waveform and high harmonic content. However, the power electronic voltage regulator needs to add corresponding control circuits and filtering links, which are costly. In addition, the reliability of the voltage regulator will be reduced when multiple links work together. The control algorithm has high requirements for high-power and high-frequency voltage regulation, and the switching loss of power electronic devices is high, which will also reduce the output efficiency.

[0005] If the brushes of the traditional voltage regulator can be omitted and the function of reducing harmonics can be achieved without the control circuit and filtering link of the power electronic voltage regulator, an AC voltage regulator with superior performance will be obtained. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, one purpose of the present invention is to provide a magnetic pole switching brushless rotary AC voltage regulator, which eliminates the brushes of the traditional voltage regulator, solves the problem of low reliability and output power limitation of the brushes, and prolongs the service life of the AC voltage regulator.

[0007] A magnetic pole switching brushless rotating AC voltage regulator according to the present invention comprises a stator, a rotor and a rotating shaft, wherein a rotor mounting groove is provided inside the stator, and the rotor is rotatably mounted inside the rotor mounting groove through the rotating shaft, a plurality of groups of winding slots 1 are evenly arranged on a side of the stator close to the rotor, a plurality of groups of winding slots 2 are evenly arranged on a side of the rotor close to the stator, a primary winding is arranged on a side of the plurality of winding slots 1 away from the rotor, the primary winding is a two-pole structure with equal-element stacked windings, a plurality of groups of winding slots 1 are arranged on a side close to the rotor, the secondary winding is a four-pole structure with equal-element stacked windings, a plurality of groups of winding slots 2 are arranged with a conversion winding, the conversion winding is a single-phase winding closed loop formed by connecting three windings in series end to end, and the number of slots at adjacent intervals between the three windings is the same.

[0008] Preferably, the primary winding and the secondary winding are isolated from each other by an isolation medium.

[0009] Preferably, the total number of slots of the multiple groups of winding slots two is 48 groups, and the 48 groups of winding slots two are numbered 1 to 48 in sequence, and the slot numbers corresponding to the three sections of winding are: 1, 2, 3, 4, 5, 6, 7, 8; 17, 18, 19, 20, 21, 22, 23, 24 and 33, 34, 35, 36, 37, 38, 39, 40, respectively. The coil corresponding to slot number 1 in the conversion winding is connected to the coil corresponding to slot number 33, the coil corresponding to slot number 8 is connected to the coil corresponding to slot number 24, and the coil corresponding to slot number 17 is connected to the coil corresponding to slot number 40. The conversion winding has a total of 24 coils.

[0010] Preferably, the number of coil turns in each group of winding slots 2 is 10, and the total number of coil turns is 240.

[0011] Preferably, the total number of the plurality of groups of winding slots one is 72 groups, and the 72 groups of winding slots one are numbered 1 to 72 in sequence.

[0012] Preferably, the slot numbers corresponding to the primary winding are: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, respectively. The coil corresponding to slot number 12 in the primary winding is connected to the coil corresponding to slot number 48, and the primary winding has a total of 24 coils.

[0013] Preferably, the number of coil turns in each group of winding slots 1 in the primary winding is 3 turns, and the total number of coil turns is 72.

[0014] Preferably, the slot numbers corresponding to the secondary winding are: 1, 2, 3, 4, 5, 6; 19, 20, 21, 22, 23, 24; 37, 38, 39, 40, 41, 42 and 55, 56, 57, 58, 59, 60. The coil corresponding to slot number 6 in the secondary winding is connected to the coil corresponding to slot number 24, the coil corresponding to slot number 19 is connected to the coil corresponding to slot number 37, the coil corresponding to slot number 42 is connected to the coil corresponding to slot number 60, and the secondary winding has a total of 24 coils.

[0015] Preferably, the number of coil turns in each group of winding slots 1 in the secondary winding is 4 turns, and the total number of coil turns is 96.

[0016] Preferably, the voltage regulation method of the magnetic pole switching brushless rotating AC voltage regulator comprises the following steps:

[0017] Define the primary winding as the A-phase input winding and the secondary winding as the B-phase output winding;

[0018] The number of pole pairs of the A-phase input winding is p1, and the number of effective turns is N1k w1 , the input voltage is U1, the number of pole pairs of the B phase output winding is p2, and the effective number of turns is N2k w2 , the output voltage is U2, N1 and N2 are the turns of the primary winding and the secondary winding, k w1 With k w2 is the winding coefficient of the primary winding and the secondary winding. The conversion winding generates the p1 pole-to-pole and p2 pole-to-pole magnetic fields at the same time. The effective number of turns corresponding to the p1 pole-to-pole magnetic field is N r k w1r , and the effective number of turns corresponding to the magnetic field of the p2 pole is N r k w2r , N r is the number of turns of the conversion winding coil, k w1r With k w2r are the winding coefficients of the conversion winding corresponding to the pole pair number p1 and the pole pair number p2 respectively, and the angle between the stator A and B phase winding axes and the conversion winding axis is θ;

[0019] When the A phase winding is energized, a voltage E is induced in the conversion winding. r1 , E r1 The calculation formula is as follows:

[0020]

[0021] Through electromagnetic induction, E r1 An electromotive force is induced in the conversion winding. Since the conversion winding is a closed loop and can generate p1 and p2 pole magnetic fields at the same time, a current I is generated in the closed loop. r, ignoring the rotor resistance, and assuming that the excitation reactances of the conversion winding corresponding to the magnetic fields of the p1 pair and p2 pair are X 1r and X 2r , the leakage reactance of the conversion winding is X σr , then the current I r The calculation formula is as follows:

[0022]

[0023] Therefore, the current I r The electromotive force E corresponding to the magnetic field of the p2 pole will be generated in the closed loop of the conversion winding. r2 , E r2 The calculation formula is as follows:

[0024] E r2 =I r ·X 2r

[0025] Since the conversion winding generates both the p1 pole-to-pole and p2 pole-to-pole magnetic fields, that is, there is mutual inductance between the conversion winding and the B-phase output winding, a voltage U2 will be induced in the B-phase winding. The calculation formula of U2 is as follows:

[0026]

[0027] Therefore, by setting the effective number of turns N1k of the winding w1 、N2k w2 、N r k w1r 、N r k w2r , and then by controlling the angle θ between the stator and rotor winding axes, the purpose of controlling the output voltage U2 of the B-phase winding is achieved.

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

[0029] (1) The primary winding and the secondary winding are placed in two layers on the stator side. The two sets of windings have little harmonic content and no mutual inductance, and are isolated from each other. Compared with the traditional inductive AC voltage regulator, the harmonic content of the output voltage is greatly reduced, and there is no need to add a filtering link to the power electronic AC voltage regulator, which saves costs and improves operational reliability.

[0030] (2) A conversion winding is placed on the rotor side. The output voltage can be adjusted by changing the magnetic pole position and changing the rotor position, eliminating the brushes of the traditional voltage regulator and not needing to add a control circuit for the power electronic voltage regulator. This greatly improves the reliability of the operation. The primary winding, secondary winding and conversion winding are isolated from each other. The contactless design can perform high-power voltage regulation and greatly improves safety performance, thereby increasing the service life of the voltage regulator.

[0031] (3) Under high-frequency working conditions, there is no requirement for control algorithm accuracy as in power electronic AC voltage regulators, and there is no high-frequency loss of switching devices, which reduces the cost of software and hardware, and thus has a better voltage regulation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In the attached picture:

[0033] Figure 1 This is a schematic diagram of the structure of the magnetic pole switching brushless rotary AC voltage regulator proposed by the present invention;

[0034] Figure 2 This is a basic working principle diagram of the magnetic pole switching brushless rotary AC voltage regulator proposed by the present invention;

[0035] Figure 3 The slot number distribution and connection diagram of the primary winding when the winding slot one is 72 slots proposed by the present invention;

[0036] Figure 4 The slot number distribution and connection diagram of the secondary winding when the winding slot 1 is 72 slots proposed by the present invention;

[0037] Figure 5 The phase diagram of the slot numbers of 48 slots on the rotor according to one pair of poles and two pairs of poles proposed by the present invention;

[0038] Figure 6 The slot number distribution and connection diagram of the conversion winding when the winding slot 2 is 48 slots proposed by the present invention;

[0039] Figure 7 This is a graph showing the relationship between the effective value of the no-load voltage output by the secondary winding and the stator-rotor included angle;

[0040] Figure 8 The angle between the stator and the rotor is 0° under no-load condition, and the relationship between the input voltage and the output voltage proposed by the present invention;

[0041] Fig. 9 The relationship between the input voltage and the output voltage when the angle between the stator and the rotor is 180° under no-load conditions proposed by the present invention;

[0042] Fig.10 A diagram showing the relationship between the voltage and the angle between the stator and rotor winding axes when the voltage regulator provided by the present invention is under load;

[0043] Fig.11 This is a load voltage waveform diagram when the axis angle between the stator and rotor windings of the voltage regulator proposed by the present invention is 0°;

[0044] Fig.12 This is a load voltage waveform diagram when the axis angle between the stator and rotor windings of the voltage regulator proposed by the present invention is 180°.

[0045] In the figure: 1-stator, 2-primary winding, 3-secondary winding, 4-rotor, 5-conversion winding, 6-rotating shaft. DETAILED DESCRIPTION

[0046] Reference Figure 1 A magnetic pole switching brushless rotary AC voltage regulator includes a stator 1, a rotor 4 and a rotating shaft 6. A rotor mounting slot is provided inside the stator 1. The rotor 4 is rotatably mounted inside the rotor mounting slot through the rotating shaft 6. Multiple groups of winding slots 1 are evenly arranged on the side of the stator 1 close to the rotor 4. Multiple groups of winding slots 2 are evenly arranged on the side of the rotor 4 close to the stator 1. A primary winding 2 is arranged on the side of the multiple groups of winding slots 1 away from the rotor 4. The primary winding 2 is a two-pole structure using equal-element stacking windings. A secondary winding 3 is arranged on the side of the multiple groups of winding slots 1 close to the rotor 4. The secondary winding 3 is a four-pole structure using equal-element stacking windings. A conversion winding 5 is arranged on the multiple groups of winding slots 2. The conversion winding 5 is a single-phase winding closed loop formed by three sections of windings connected in series end to end. The number of slots between adjacent intervals of the three sections of windings is the same. The primary winding 2 and the secondary winding 3 are isolated from each other by an isolation medium.

[0047] Reference Figure 2 , Figure 2 The following is the basic working principle diagram of the magnetic pole switching brushless rotary voltage regulator. There are two sets of windings on the stator 1, the primary winding 2 is the input winding, and the secondary winding 3 is the output winding, which are placed on the upper and lower layers of the stator slots and are respectively recorded as phase A and phase B. The phase A input winding has a pole pair number of p1 and an effective number of turns of N1k w1 , input voltage is U1, B phase output winding, pole pair number is p2, effective turns number is N2k w2 , the output voltage is U2, N1 and N2 are the coil turns of the primary winding 2 and the secondary winding 3, k w1 With k w2 is the winding coefficient of the primary winding 2 and the secondary winding 3. The axes of the two-phase windings A and B coincide, but due to the different number of pole pairs, the mutual inductance is zero and they are decoupled from each other. The conversion winding is composed of three sections a, b, and c connected in series, forming a single-phase winding closed loop, so no brush is required. The conversion winding 5 can simultaneously generate the p1 pole-to-pole and p2 pole-to-pole magnetic fields, and the effective number of turns corresponding to the p1 pole-to-pole magnetic field is N r k w1r , the effective number of turns corresponding to the magnetic field of the p2 pole is N r k w2r , N r is the number of turns of the conversion winding coil, k w1r With k w2r are the winding coefficients of the conversion winding corresponding to the pole pair number p1 and the pole pair number p2 respectively. The axis of the conversion winding 5 coincides with the axis of the winding of segment a. The angles between the axes of the stator A and B phase windings and the axis of the conversion winding are θ and θ mechanical angles.

[0048] When the A-phase winding is energized, a voltage E is induced in the rotor winding. r1 , E r1 The value of is calculated as follows:

[0049]

[0050] Through electromagnetic induction, E r1 An electromotive force will be induced in the conversion winding. Since the conversion winding 5 is a closed loop and can generate the magnetic field of the p1 pole pair and the p2 pole pair at the same time, a current I will be generated in the closed loop. r If the rotor resistance is ignored and the excitation reactance of the conversion winding 5 corresponding to the magnetic field of the p1 pair and the p2 pair is X 1r and X 2r , the leakage reactance of the conversion winding 5 is X σr , then the current I r It can be expressed by the formula:

[0051]

[0052] Therefore, the current I r The electromotive force E corresponding to the magnetic field of the p2 pole will be generated in the closed loop of the conversion winding 5. r2 , E r2 The value of can be expressed by the formula:

[0053] E r2 =I r ·X 2r (3)

[0054] Since the conversion winding 5 can generate the p1 pole-to-pole and p2 pole-to-pole magnetic fields at the same time, that is, there is mutual inductance between the conversion winding 5 and the B-phase output winding, a voltage U2 will be induced in the B-phase winding at this time. The value of U2 can be expressed by the formula:

[0055]

[0056] From the above analysis, we can know that by setting the effective number of turns N1k of the winding w1 、N2k w2 、N r k w1r 、N r k w2r , and then by controlling the angle θ between the stator and rotor winding axes, the purpose of controlling the output voltage U2 of the B-phase winding is achieved.

[0057] Embodiment 1:

[0058] like Figure 1As shown, 72 slots are opened at equal distances on the stator core, and the primary winding 2 and the secondary winding 3 are placed on the upper and lower sides of the stator slots respectively, and the axes of the two coincide. The primary winding 2 is designed as a two-pole structure, and the secondary winding 3 is designed as a four-pole structure, that is, p1=1, p2=2. The primary winding 2 and the secondary winding 3 are set according to the AC motor winding theory to reduce the magnetic potential harmonics generated by the winding power-on and decouple the two-phase windings from each other.

[0059] like Figure 3 The figure shows the slot number distribution and connection diagram of the primary winding 2. The pitch of the primary winding 2 is 24, that is, the use of 2 / 3 times the full pitch can eliminate the third harmonic content and multiples of 3. Each coil has 3 turns, and there are 24 coils in total, so the number of turns of the primary winding 2 is 72, that is, N1 = 72. Figure 3 It can also be seen that the primary winding 2 is composed of two branches in series, the first branch is composed of coils in slot numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and the second branch is composed of coils in slot numbers 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48. The two branches are connected in series in reverse order to form a two-pole winding structure. The magnetic potential harmonics of the primary winding 2 are analyzed according to the theory of AC motor windings. Table 1 shows the harmonic analysis results of the primary winding 2. It can be seen that there are only (6n±1)·p1 harmonics for the number of poles. Combined with the percentage of the magnetic potential harmonic amplitude, it can be seen that in addition to the fundamental content, there are only a small amount of 5th and 7th harmonics, and there is almost no other harmonic content, and the 3rd and multiple harmonics of 3 are completely eliminated. Although a small amount of 5th and 7th harmonics will be generated when the primary winding 2, i.e. the input winding, is energized, according to the harmonic electromotive force formula under the ν pair:

[0060] E φν =4.44f ν NK wν φ ν (5)

[0061] Where: f ν is the harmonic frequency of ν pole to pole, N is the total number of series turns of the winding, K wν is the winding coefficient under ν pole pair, φ ν is the magnetic flux of the ν-pole harmonic magnetic field.

[0062] It can be known that if the secondary winding 3, i.e., the output winding, does not have a winding coefficient of the corresponding number of poles, then the secondary winding 3 will not generate voltage harmonic content of the corresponding number of poles when it is actually output. Therefore, the purpose of reducing harmonics can be achieved by setting the secondary winding 3, and combined with the design of the conversion winding on the rotor side, the performance of the present invention can be further improved.

[0063] Table 1 Statistics of harmonic analysis results of primary winding 2

[0064] Number of poles Winding factor Magnetic potential harmonic amplitude percentage (%) 2 0.8273 100 10 0.1667 4.0306 14 0.1200 2.0722 22 0.0781 0.8588 26 0.0672 0.6245 34 0.0534 0.3798 38 0.0489 0.3114 46 0.0428 0.2249 50 0.0407 0.1967 58 0.0378 0.1557 62 0.0370 0.1441 70 0.0361 0.1247 74 0.0361 0.1180

[0065] like Figure 4 The figure shows the slot number distribution and connection diagram of the secondary winding 3. The pitch of the secondary winding 3 is 12, and the 2 / 3 times full pitch is also used to eliminate the third harmonic content and multiples of 3. The secondary winding 3 is designed as a four-pole winding structure, each coil has 4 turns, and there are 24 coils in total, so the number of turns of the secondary winding 3 is 96, that is, N2 = 96. Figure 4 It can also be seen that the secondary winding 3 is composed of four branches connected in series. The first branch is composed of coils in slot numbers 1, 2, 3, 4, 5, and 6. The second branch is composed of coils in slot numbers 19, 20, 21, 22, 23, and 24. The third branch is composed of coils in slot numbers 37, 38, 39, 40, 41, and 42. The fourth branch is composed of coils in slot numbers 55, 56, 57, 58, 59, and 60. The second branch and the fourth branch are connected in series in reverse with the other two branches to form a four-pole winding structure. The magnetic potential harmonics of the secondary winding 3 are also analyzed according to the AC motor winding theory. The results are shown in Table 2.

[0066] Table 2 Statistics of harmonic analysis results of secondary winding 3

[0067] Number of poles Winding factor Magnetic potential harmonic amplitude percentage (%) 4 0.8280 100 20 0.1708 4.1246 28 0.1258 2.1707 44 0.0881 0.9673 52 0.0796 0.7397 68 0.0724 0.5146 76 0.0724 0.4605 92 0.0796 0.4181 100 0.0881 0.4256

[0068] It can be seen from Table 2 that, similar to the harmonic order of the primary winding 2, the magnetic potential harmonics generated by the secondary winding 3 are only (6n±1)·p2 harmonics of the number of poles, and the 3rd and multiple harmonics of 3 are completely eliminated. It can also be obtained that the magnetic potential harmonics generated by the primary winding 2 and the magnetic potential harmonics generated by the secondary winding 3 have no intersection at all, so there is no mutual inductance between the primary winding 2 and the secondary winding 3, and the two are decoupled from each other. Similarly, combined with the percentage of the magnetic potential harmonic amplitude, it can be seen that in addition to the fundamental content, it still contains a small amount of 5th, 7th and tooth harmonics, but according to formula (5), by cooperating with the primary winding 2 and combining the setting of the rotor side conversion winding 5, the effect of reducing harmonics can be further achieved.

[0069] The rotor winding design method of the magnetic pole switching brushless rotary voltage regulator adopts the "common slot number method"; the winding designed by this method is to make a set of windings produce two main magnetic poles of basically the same size. First, calculate the appropriate coil pitch y1 according to the number of slots on the rotor. Then, according to the number of pole pairs p corresponding to the two sets of windings on the stator c and p p, make a rotor slot number phase table under the corresponding pole pair number, and select the common slot number. Then connect the coils with the common slot number into a new winding, use the harmonic analysis program to analyze the winding magnetomotive force and optimize the slot number. It should be noted that:

[0070] (1) The number of slots in the rotor and the pitch of the coil are very important. The design concept of the brushless rotary voltage regulator rotor is to c The extreme harmonics are amplified to basically reach the same level as p p The fundamental waves of the opposite poles are the same. Only by selecting the appropriate coil pitch y1 can p c The winding coefficient of the poles is strengthened and the corresponding harmonics are eliminated.

[0071] (2) and modulated rotor winding, p p Antipodes and p c The phase sequence of the phase diagram of the opposite pole slot number should be opposite. Reasonably select the phase band m and the phase band width, and further draw p p Antipodes and p c Slot number phase diagram of the pole winding coil. According to the slot number phase diagram, select the slot number coils shared by the same phase belt and discard the non-shared slot number coils.

[0072] (3): Connect the coils with the same slot number in sequence to form an m-phase winding. And further optimize and weaken the harmonics, and select the corresponding winding connection method according to the designer's usage.

[0073] When the pole pairs corresponding to the two sets of windings on the stator are 1 and 2 respectively and the rotor winding 5 is a modulated winding, the 48 slots on the rotor (slot numbers are 1 to 48 respectively) are arranged according to the phase table of one pair of poles and two pairs of poles slot numbers as follows: Figure 5 As shown in Figure 3, the phase table is divided into 6 phase bands and 3 phase bands according to the 60° phase band and the 120° phase band, respectively. The common slot numbers in the phase table of one-pole and two-pole slot numbers are marked in Table 3. When only the common slot numbers of the 60° phase band are used, as shown in Table 3, the magnetic potential components of one-pole and two-pole pairs are 100% and 48.4% respectively, both of which are greater than the harmonic components of other pole pairs. However, the slot utilization rate is low and there are some higher magnetic potential components of other pole pairs. The slot number needs to be further optimized according to the harmonic analysis program. When all the common slot numbers of the 120° phase band are used, as shown in Table 4, the magnetic potential components of one-pole and two-pole pairs are 100% and 53.4858% respectively. Compared with the case of using only the common slot numbers of the 60° phase band, the harmonic components of other pole pairs are reduced, but the winding coefficients are all reduced. As needed, slot numbers can be added based on the common slot numbers of the 60° phase belt, or slot numbers can be reduced based on the common slot numbers of the 120° phase belt. Then, a harmonic analysis program can be used to analyze and optimize the solution to select a solution that better suits current needs.

[0074] Table 3

[0075] Number of poles Winding factor Magnetic potential harmonic amplitude percentage (%) 2 0.8568 100 4 0.8294 48.4 8 0.7224 21.1386 10 0.6506 15.1872 14 0.4728 7.8839 16 0.3750 5.4711 20 0.1778 2.0755

[0076] Table 4

[0077] Number of poles Winding factor Magnetic potential harmonic amplitude percentage (%) 2 0.6838 100 4 0.7314 53.4858 8 0.2415 8.8292 10 0.3266 9.5530 14 0.2374 4.9591 16 0.1250 2.2852 20 0.1568 2.2936

[0078] Figure 6 The slot number distribution and connection diagram of the conversion winding 5 are shown in FIG. Figure 6 As shown, the pitch of the conversion winding 5 is set to 16, and it is composed of three branches connected in series to form a closed loop. The first branch is composed of coils in slots 1, 2, 3, 4, 5, 6, 7, and 8, the second branch is composed of coils in slots 17, 18, 19, 20, 21, 22, 23, and 24, and the third branch is composed of coils in slots 33, 34, 35, 36, 37, 38, 39, and 40. Each coil has 10 turns, and there are 24 coils in total. Therefore, the number of turns of the conversion winding is 240, that is, N r =240. The axis of the conversion winding 5 changes with the change of the rotor position, and the brushless AC voltage regulation is performed by controlling the angle θ between the axis of the primary winding 2 and the secondary winding 3 and the axis of the conversion winding 5. Similarly, the magnetic potential harmonics of the conversion winding are analyzed according to the AC motor winding theory, and the results are shown in Table 5:

[0079] Table 5 Statistics of harmonic analysis results of conversion winding

[0080] Number of poles Winding factor Magnetic potential harmonic amplitude percentage (%) 2 0.8276 100 4 0.7182 43.9342 8 0.3622 10.9422 10 0.1684 4.0694 14 0.1224 2.1125 16 0.1875 2.8320 20 0.1540 1.8609 22 0.0821 0.9018 26 0.0720 0.6692 28 0.1182 1.0199 32 0.1083 0.8175 34 0.0604 0.4290 38 0.0572 0.3635 40 0.0971 0.5864

[0081] It can be seen from the harmonic analysis results that the conversion winding 5 can generate harmonics of (3n±1)·p1 pairs of poles, so the conversion winding 5 can generate both a dipolar and a quadrupole magnetic field. The dipolar induced electromotive force induced in the conversion winding 5 by the primary winding 2 will flow through the conversion winding 5 because the conversion winding 5 is a closed coil, generating a quadrupole magnetic field. The quadrupole magnetic field of the conversion winding 5 acts on the secondary winding 3, causing the secondary winding 3 to output a voltage, thereby achieving the function of converting magnetic poles and realizing brushless voltage regulation. From the percentage result of the magnetic potential harmonic amplitude of the conversion winding 5, in addition to the high content of the 2-pole magnetic field and the 4-pole magnetic field required for the magnetic pole conversion, some 8-pole, 10-pole, 14-pole and 16-pole magnetic fields will also be generated. However, combined with the harmonic analysis results of the primary winding 2 and the secondary winding 3, theoretically, the harmonic content finally output from the secondary winding 3 should only have a small amount of 20-pole and 28-pole harmonics, because for the secondary winding 3, the harmonic winding coefficient of 8-pole, 10-pole, 14-pole and 16-pole is 0. Although the secondary winding 3 will output 20-pole and 28-pole harmonics, the 20-pole and 28-pole magnetic fields generated by the conversion winding 5 are very small, thereby effectively filtering out the 20-pole and 28-pole harmonics, so the harmonic content output by the magnetic pole conversion brushless rotary AC voltage regulator designed in this way is very low.

[0082] By changing the angle θ between the stator and rotor winding axes, the output voltage can be controlled. A pole-switching brushless rotary AC voltage regulator designed according to the above preferred scheme is analyzed for its no-load characteristics through finite element modeling and simulation. When the primary winding 2 is connected to a 50Hz effective value of 70V voltage, the relationship between the no-load voltage effective value output by the secondary winding and the stator-rotor angle is as follows: Figure 7 shown.

[0083] from Figure 7 It can be seen from the figure that the no-load voltage changes with the angle in a certain regular pattern, and from the previous formula (2) and formula (4), it can be seen that the no-load voltage will pass through zero. Because the primary winding 2 is a two-pole structure and the secondary winding 3 is a four-pole structure, that is, p1=1, p2=2, the no-load voltage will pass through zero when the stator-rotor angle is 45° and 90°. Since the motor is a symmetrical structure, the no-load voltage will be symmetrical with the angle at 90° and 180°. The figure shows the change of the no-load voltage with the angle from 0° to 180°. The negative voltage effective value in the figure indicates that the output voltage is in reverse phase with the input voltage. Therefore, voltage regulation between 0° to 45° and 135° to 180° can achieve good results.

[0084] It can also be seen that when the angle between the stator and the rotor is 0°, the axes of the stator and rotor windings coincide, and the no-load voltage output value of the secondary winding 3 is the largest; when the angle between the stator and the rotor is 180°, the axes of the stator and rotor windings also coincide, and the no-load voltage output value of the secondary winding 3 is also the largest, but the phase is opposite to the input voltage of the primary winding 2. Figure 8 and Fig. 9 They are the relationship between the input voltage and the output voltage when the angle between the stator and the rotor is 0° and 180° under no-load conditions. It can also be clearly seen that the output voltages are in opposite phases when the stator and rotor angles are 0° and 180°, and the output waveform is a standard sinusoidal waveform, which also confirms that the harmonic content is very small, proving that the harmonic content can be greatly reduced by designing the primary winding 2, the secondary winding 3 and the conversion winding 5.

[0085] In addition, it can be seen that the output voltage is slightly larger than the input voltage when no-load. According to formula (1) and formula (4), because the number of turns of the primary winding 2 is 72, that is, N1=72, the number of turns of the secondary winding 3 is 96, that is, N2=96, the number of turns of the secondary winding 3 is slightly larger than the number of turns of the primary winding 2, so the no-load output voltage is slightly larger than the input voltage. Moreover, this design scheme is a preferred scheme, and the number of poles and harmonics required to be converted, as well as the turns ratio, etc. can be designed according to actual needs.

[0086] From the above, it can be seen that the no-load characteristics meet the theoretical analysis and design requirements, but the voltage regulator needs to run with load when it is operating normally. Therefore, it is necessary to verify whether the designed magnetic pole switching brushless rotary voltage regulator can work normally under load and meet the engineering requirements. Through finite element modeling and simulation, an 8Ω pure resistive load is connected to the secondary winding 3, and the relationship between the effective value of its load voltage and the stator-rotor angle is calculated. The results are as follows Fig.10 shown.

[0087] from Fig.10 It can be seen that Figure 7 Compared with the graph of no-load voltage changing with angle, the corresponding voltage value of load voltage is slightly lower than the no-load voltage value under the same conditions. This is because there is a leakage impedance voltage drop under load state, but the law of change of load voltage with angle is the same as that under no-load state, which means that under load, the voltage can be adjusted by changing the angle between the stator and rotor, which verifies that the magnetic pole switching brushless rotary voltage regulator of the present invention can operate normally under load. Similarly, the relationship between the input voltage and the output voltage when the angle between the stator and rotor is 0° and 180° under load is compared, as shown in FIG. Fig.11 and Fig.12 shown.

[0088] Compared with the no-load voltage, the load voltage value is slightly lower than the no-load voltage value due to the impedance voltage division. Similarly, when the stator-rotor angle is 0° and 180°, the output voltage phases of the two are opposite, and the output waveform is a standard sinusoidal waveform.

[0089] Therefore, as a preferred solution of a magnetic pole switching brushless rotating AC voltage regulator of the present invention, the harmonic content can be greatly reduced through the special design of the primary winding, the secondary winding and the conversion winding, and there is no need to increase the filtering link of the power electronic AC voltage regulator, which saves costs. The output voltage can be adjusted by changing the rotor position through magnetic pole conversion, eliminating the brushes of the traditional voltage regulator, and there is no need to increase the control circuit of the power electronic voltage regulator, which greatly improves the working reliability and increases the service life of the voltage regulator. At the same time, the contactless design can perform high-power voltage regulation and greatly improves the safety performance. Therefore, the magnetic pole switching brushless rotating AC voltage regulator proposed by the present invention has superior performance and better voltage regulation effect than other voltage regulators, and has important application value in the field of AC voltage regulators.

Claims

1. A magnetic pole switching brushless rotary AC voltage regulator, characterized in that: The invention comprises a stator (1), a rotor (4) and a rotating shaft (6), wherein a rotor mounting groove is provided inside the stator (1), and the rotor (4) is rotatably mounted inside the rotor mounting groove via the rotating shaft (6); a plurality of groups of winding slots 1 are evenly arranged on a side of the stator (1) close to the rotor (4); a plurality of groups of winding slots 2 are evenly arranged on a side of the rotor (4) close to the stator (1); a primary winding (2) is arranged on a side of the plurality of winding slots 1 away from the rotor (4); the primary winding (2) is a two-pole structure using an equal-element stacked winding; a plurality of groups of winding slots 1 are arranged on a side close to the rotor (4); the secondary winding (3) is a four-pole structure using an equal-element stacked winding; a plurality of groups of winding slots 2 are arranged on a conversion winding (5), and the conversion winding (5) is a single-phase winding closed loop formed by connecting three sections of winding in series end to end, and the number of slots between adjacent intervals of the three sections of winding is the same.

2. A magnetic pole switching brushless rotary AC voltage regulator according to claim 1, characterized in that: The primary winding (2) and the secondary winding (3) are isolated from each other by an isolation medium.

3. The magnetic pole switching brushless rotary AC voltage regulator according to claim 1, characterized in that: The total number of slots of the plurality of groups of winding slots 2 is 48 groups, and the 48 groups of winding slots 2 are numbered 1 to 48 in sequence. The slot numbers corresponding to the three sections of winding are: 1, 2, 3, 4, 5, 6, 7, 8; 17, 18, 19, 20, 21, 22, 23, 24 and 33, 34, 35, 36, 37, 38, 39, 40, respectively. In the conversion winding (5), the coil corresponding to slot number 1 is connected to the coil corresponding to slot number 33, the coil corresponding to slot number 8 is connected to the coil corresponding to slot number 24, and the coil corresponding to slot number 17 is connected to the coil corresponding to slot number 40. The conversion winding (5) has a total of 24 coils.

4. The magnetic pole switching brushless rotary AC voltage regulator according to claim 3, characterized in that: The number of coil turns in each group of winding slots 2 is 10, and the total number of coil turns is 240.

5. The magnetic pole switching brushless rotary AC voltage regulator according to claim 1, characterized in that: The total number of the plurality of groups of winding slots one is 72 groups, and the 72 groups of winding slots one are numbered 1 to 72 in sequence.

6. A magnetic pole switching brushless rotary AC voltage regulator according to claim 5, characterized in that: The slot numbers corresponding to the primary winding (2) are: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, respectively. The coil corresponding to slot number 12 in the primary winding (2) is connected to the coil corresponding to slot number 48, and the primary winding (2) has a total of 24 coils.

7. A magnetic pole switching brushless rotary AC voltage regulator according to claim 6, characterized in that: The number of coil turns in each group of winding slots 1 in the primary winding (2) is 3 turns, and the total number of coil turns is 72.

8. The magnetic pole switching brushless rotary AC voltage regulator according to claim 5, characterized in that: The slot numbers corresponding to the secondary winding (3) are: 1, 2, 3, 4, 5, 6; 19, 20, 21, 22, 23, 24; 37, 38, 39, 40, 41, 42 and 55, 56, 57, 58, 59, 60. The coil corresponding to slot number 6 in the secondary winding (3) is connected to the coil corresponding to slot number 24, the coil corresponding to slot number 19 is connected to the coil corresponding to slot number 37, and the coil corresponding to slot number 42 is connected to the coil corresponding to slot number 60. The secondary winding (3) has a total of 24 coils.

9. A magnetic pole switching brushless rotary AC voltage regulator according to claim 8, characterized in that: The number of coil turns in each group of winding slots 1 in the secondary winding (3) is 4, and the total number of coil turns is 96.

10. A voltage regulating method for a magnetic pole switching brushless rotating AC voltage regulator according to any one of claims 1 to 9, characterized in that: The method steps are as follows: Define the primary winding (2) as the A-phase input winding, and the secondary winding (3) as the B-phase output winding; The number of pole pairs of the A-phase input winding is p1, and the number of effective turns is N1k w1 , the input voltage is U1, the number of pole pairs of the B phase output winding is p2, and the effective number of turns is N2k w2 , the output voltage is U2, N1 and N2 are the turns of the primary winding (2) and the secondary winding (3), k w1 With k w2 is the winding coefficient of the primary winding (2) and the secondary winding (3), the conversion winding (5) generates the p1 pole-to-pole magnetic field and the p2 pole-to-pole magnetic field at the same time, and the effective number of turns corresponding to the p1 pole-to-pole magnetic field is N r k w1r , and the effective number of turns corresponding to the magnetic field of the p2 pole is N r k w2r , N r is the number of turns of the conversion winding coil, k w1r With k w2r are the winding coefficients of the conversion winding (5) corresponding to the pole pair number p1 and the pole pair number p2 respectively, and the angle between the axis of the stator A and B phase windings and the axis of the conversion winding (5) is θ; When the A-phase winding is energized, a voltage E is induced in the conversion winding (5). r1 , E r1 The calculation formula is as follows: Through electromagnetic induction, E r1 An electromotive force is induced in the conversion winding (5). Since the conversion winding (5) is a closed loop and can generate the magnetic field of the p1 pole pair and the p2 pole pair at the same time, a current I is generated in the closed loop. r , ignoring the rotor resistance, and assuming that the excitation reactances of the conversion winding (5) corresponding to the magnetic fields of the p1 pair and p2 pair are X 1r and X 2r , the leakage reactance of the conversion winding (5) is X σr , then the current I r The calculation formula is as follows: Therefore, the current I r The electromotive force E corresponding to the magnetic field of the pole p2 will be generated in the closed loop of the conversion winding (5). r2 , E r2 The calculation formula is as follows: E r2 =I r ·X 2r Since the conversion winding (5) generates the p1 pole-to-pole magnetic field and the p2 pole-to-pole magnetic field at the same time, that is, there is mutual inductance between the conversion winding (5) and the B-phase output winding, a voltage U2 will be induced in the B-phase winding. The calculation formula of U2 is as follows: Therefore, by setting the effective number of turns N1k of the winding w1 、N2k w2 、N r k w1r 、N r k w2r , and then by controlling the angle θ between the stator and rotor winding axes, the purpose of controlling the output voltage U2 of the B-phase winding is achieved.

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