A design method of a brushless double rotor motor combined winding structure

Abstract

The application discloses a design method of a combined winding structure of a brushless double-rotor motor, and belongs to the technical field of power generation, power transformation or power distribution. The method determines the range of the ratio of the outer-rotor magnetic conductive block to the inner-rotor pole pair number according to the rated torque of the inner and outer rotors; based on the determined ratio range, the concentrated winding design of the stator winding is carried out, and all pole-slot combinations are exhausted by considering the high self-winding factor and the low mutual-winding factor; a finite element model is established, and the back electromotive force of the two sets of windings is analyzed by FFT; the pole-slot combination meeting the decoupling control requirement is screened out; the winding sequence of the screened pole-slot combination is rearranged, and the pole-slot combination with the highest winding combination rate is selected; the combined winding is combined in the same tooth, the coils with the same current direction and the same number of turns; and a combined winding structure is generated through series-parallel connection. The scheme can not only realize the mutual decoupling and separate control of the windings, but also has a simpler structure and generates smaller copper loss under the same current injection level.

Description

Technical Field

[0001] This invention relates to motor technology, and more particularly to stator winding structure design technology. Specifically, it discloses a design method for a combined winding structure of a brushless dual-rotor motor, belonging to the technical field of power generation, power transformation, or power distribution. Background Technology

[0002] Series-parallel hybrid systems have garnered widespread attention due to their high fuel economy and excellent driving performance. However, most existing series-parallel hybrid systems are based on planetary gear systems, which suffer from wear and lubrication issues. Brushless dual-rotor motors offer an excellent alternative to planetary gear systems. A brushless dual-rotor motor has one stator and two rotors. The stator has two sets of windings that are decoupled and controlled independently, thus decoupling the torque and speed of the two rotors.

[0003] However, the two sets of windings on the stator of a brushless dual-rotor motor increase the complexity of the stator winding structure. Furthermore, the resistance of the stator shared by two sets of windings is greater than that of a single set of windings on a single stator, resulting in greater copper losses at the same current injection level. Therefore, a new stator winding structure is urgently needed that not only achieves decoupling and independent control between the windings but also has a simpler structure and generates less copper loss at the same current injection level.

[0004] Chinese invention patent application CN120956018A discloses a common-winding motor with ultra-flat wire and its design method. This method employs an "equal-pole common-winding" configuration where the stator and rotor have the same number of magnetic poles. Using ultra-flat wire windings, through concentric winding or serpentine routing, all magnetic poles on the same disk are excited by a single ring winding, thus achieving a separation design between the windings and magnetic poles. The advantages of this method are that it achieves an end-less winding design, bringing the winding utilization rate close to 100%, significantly improving power density and efficiency, simplifying the winding manufacturing and assembly process, and improving heat dissipation. The disadvantages are that the equal-pole common-winding and split-disc structure lead to a complex overall motor configuration, requiring higher precision in core processing and ultra-flat wire winding technology, and the multi-disc complementary control strategy increases system complexity and cost.

[0005] Chinese invention patent application CN120414970A proposes a design method for AC windings capable of generating multi-pole magnetomotive forces (MTFs). This method involves selecting multiple three-phase symmetrical winding units, each corresponding to a fundamental pole pair number of a specific MMF, and connecting windings of the same phase in series to form a star-connected winding assembly. The initial arrangement of the windings in the core slots is determined based on the pole pair number. Then, based on the equal ampere-turn principle, the conductors within the slots are merged and simplified, such as deleting conductors with zero sum of MMFs or replacing them with equivalent conductors, ultimately resulting in a simplified winding arrangement. This method can generate multiple dominant wave MMFs with arbitrary pole pair numbers and directions without changing the air gap permeability, suppressing unwanted harmonics, improving conductor utilization, and providing a multi-dominant wave collaborative working path for new special motors. The disadvantages include a complex design process requiring precise calculation and optimization, and specific limitations on the slot structure, such as a minimum slot number of six times the least common multiple of the pole pair number when using integer slots, which may increase manufacturing difficulty.

[0006] Chinese invention patent application CN109286258B discloses a method for preparing a wound rotor winding for an AC brushless doubly-fed induction generator. This method combines a three-phase double-layer sub-winding and a three-phase single-layer sub-winding to form a three-phase three-layer winding with a specific pole pair ratio, such as 2:4. It employs a slot-splitting technique to increase the number of rotor slots and adjusts parameters such as the number of coil splits, pitch, and phase axis spacing to ultimately form a rotor winding where each phase is a self-contained circuit. The advantages of this method are a reasonable coil distribution, regular end structure, and neat wiring arrangement, which effectively reduces harmonic content, improves winding coefficient and performance, and the design method is relatively simple. Its disadvantages are that it is mainly applicable to specific pole pair ratios, such as 2:4, limiting its application range, and the winding structure is still more complex than conventional windings, requiring precise control of multiple parameters during design and manufacturing.

[0007] Chinese invention patent application CN104578611B proposes a design method for a third harmonic excitation winding of a salient-pole synchronous generator. This method employs a bipolar slot number phase diagram method, merging slot number phase diagrams for two different pole pair numbers. Parameters are determined based on the unit winding parameter method, and finally, the slot number and coil pitch of the stator winding are selected according to this diagram, designing a shared winding capable of simultaneously generating fundamental and third harmonic currents. The advantages of this method are its simple structure, low copper loss, and intuitive and clear design process, reducing complexity. The disadvantages are strict limitations on the number of stator slots, such as the number of slots needing to be odd, divisible by 3, and ≥27, thus limiting its application range. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a design method for a combined winding structure of a brushless dual rotor motor. This method achieves the goal of simplifying the stator winding structure of the brushless dual rotor motor and generating less copper loss under the same current injection level, while realizing mutual decoupling and independent control between the windings. This solves the technical problem of large copper loss in the stator winding structure of existing brushless dual rotor motors.

[0009] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0010] A design method for a combined winding structure of a brushless dual-rotor motor includes:

[0011] Step 1: Determine the range of the ratio of the number of magnetic blocks of the outer rotor to the number of pole pairs of the inner rotor based on the rated torque of the inner and outer rotors.

[0012] Step 2: Based on the stator winding concentrated winding design, and considering the high self-winding factor and low mutual winding factor, exhaustively search all pole slot combinations under the constraint of the ratio of the number of outer rotor magnetic blocks to the number of inner rotor pole pairs.

[0013] Step 3: Perform FFT analysis on the back electromotive force of the two windings under all pole-slot combinations exhaustively listed in Step 2, and screen out the pole-slot combinations that meet the decoupling control requirements.

[0014] Step 4: For the pole slot combinations selected in Step 3, rearrange the sequence of the two sets of windings under each pole slot combination, and select the pole slot combinations whose winding combination rate reaches the threshold.

[0015] Step 5: For the two sets of windings with the highest winding combination rate under the pole slot combination, combine the coils wound on the same stator tooth, with the same energizing direction and the same number of turns.

[0016] Step 6: Connect the unmerged portions of the two sets of windings in series and parallel, as well as the merged winding, to obtain a merged winding structure in which the circulating current meets the design specifications.

[0017] As a further optimization of the design method for the combined winding structure of a brushless dual-rotor motor, step 1, based on the rated torque of the inner and outer rotors, determines the specific method for the range of the ratio of the outer rotor's magnetic block to the inner rotor's pole pair number. This method considers that when the brushless dual-rotor motor is in its rated operating state, both sets of windings output positive force to the outer rotor, while the rated torque of the inner rotor is entirely provided by the modulation winding. Therefore, the brushless dual-rotor motor is considered as a flux-modulated motor coupled with a permanent magnet synchronous motor. Determine the range of the ratio of the number of magnetic blocks in the outer rotor to the number of pole pairs in the inner rotor, where, This refers to the number of magnetic blocks on the outer rotor of a brushless dual-rotor motor. This refers to the number of rotor pole pairs in a brushless dual-rotor motor. , The rated torque of the inner and outer rotors of the brushless dual-rotor motor is... , The number of permanent magnet pole pairs on the outer rotor of a brushless dual-rotor motor. , , , To modulate the torque of the inner and outer rotors of the motor, This represents the torque on the outer rotor of the permanent magnet synchronous motor.

[0018] As a further optimization of the design method for the combined winding structure of a brushless dual-rotor motor, the specific method for exhaustively exploring all pole-slot combinations in step 2 under the constraint of the ratio of the number of outer rotor magnetic blocks to the number of inner rotor pole pairs is as follows: Define the self-winding factor. With mutual winding factor as follows: , ,in, This represents the total number of coil groups in a single phase winding. represents an imaginary number, for The magnetic field electric angle corresponding to coil number P1 is P1. Let P1 be the electric angle of the magnetic field corresponding to a pole pair number P1 under a span of one stator tooth. for The magnetic field electric angle corresponding to coil number P2 is P2. The electrical angle of the magnetic field with a span of P2 corresponding to one stator tooth and a pole pair number of P2 is given by the stator outer diameter, which limits the total number of slots. The maximum value is used to select pole slot combinations with a self-winding factor higher than 0.6 and a mutual winding factor lower than 0.1, under the constraint of the ratio of the number of outer rotor magnetic blocks to the number of inner rotor pole pairs.

[0019] As a further optimization scheme of the design method of the combined winding structure of a brushless dual rotor motor, in step 3, the back electromotive force of the two sets of windings under all pole-slot combinations exhaustively listed in step 2 is analyzed by FFT. The specific method for screening the pole-slot combinations that meet the decoupling control requirements is as follows: perform FFT analysis on the no-load back electromotive force of the two sets of windings under all pole-slot combinations exhaustively listed in step 2, and discard the pole-slot combinations corresponding to the no-load back electromotive force harmonics exceeding the threshold and the two sets of windings not being decoupled from each other.

[0020] As a further optimization of the design method for the combined winding structure of a brushless dual-rotor motor, the specific method of step 4 is as follows: For the two sets of windings under each pole slot combination selected in step 3, based on the slot conductor electromotive force star diagram under the 60-degree phase band division, the slot conductors located under the A+, B+, C+ and A-, B-, C- phase bands are selected, and the slot conductors of the two sets of windings located under the same phase band are transferred to one slot. After counting the total number of coils wound on the same stator tooth with the same energizing direction, the winding combination rate is calculated. , Among them, coils wound on the same stator tooth and with the same energizing direction are called combinable coils. To determine the total number of coils that can be combined between the two sets of windings, select pole-slot combinations where the winding combination rate reaches a threshold.

[0021] As a further optimization of the design method of merging winding structure of brushless dual rotor motor, the specific method of merging coils in step 5 is as follows: For coils wound on the same toothed stator, with the same energizing direction and the same number of turns, a new coil is used to replace the coils wound on the same toothed stator, with the same energizing direction and the same number of turns in the two sets of windings. The cross-sectional area of ​​the new coil is twice the cross-sectional area of ​​a single-turn coil in the two sets of windings, and the number of turns of the new coil is the same as the number of turns of the coil in the original set of windings.

[0022] As a further optimization of the design method of the combined winding structure of a brushless dual rotor motor, the specific method of connecting the uncombined parts of the two sets of windings in series and parallel in step 6 and the combined winding is as follows: connect the ends of the uncombined parts of the two sets of windings in series with the first segment of the combined winding in phase sequence, and connect the ends of the combined winding in a star or delta configuration.

[0023] A combined winding structure for a brushless dual-rotor motor, obtained using the above design method, comprises: an uncombined portion of a first set of windings, an uncombined portion of a second set of windings, and a combined winding. The ends of the uncombined portions of the two sets of windings are respectively connected in series with the first segment of the combined winding in phase sequence. The ends of the combined winding are connected in a star or delta configuration. Three-phase current is passed through the first segment of the uncombined portions of the two sets of windings.

[0024] A stator structure for a brushless dual-rotor motor includes: a modulation winding, a torque winding, and a stator. The modulation winding and the torque winding are a combined winding structure as described above, and the combined winding structure is wound on the stator.

[0025] A brushless dual-rotor motor includes an inner rotor, an outer rotor, and the aforementioned stator structure, wherein the inner rotor, outer rotor, and stator structure are concentrically nested.

[0026] The present invention, by adopting the above technical solution, has the following beneficial effects:

[0027] (1) The merging winding structure design method proposed in this invention is based on the premise that the original windings are decoupled from each other and do not affect each other, and the newly synthesized winding structure does not affect the original torque effect. This means that general motor control technology can be used without decoupling, which simplifies the control complexity.

[0028] (2) The combined winding structure proposed in this invention reduces the number of coil turns wound on one tooth, thereby improving the inter-turn insulation performance and reducing manufacturing requirements, which is beneficial in both manufacturing and subsequent maintenance.

[0029] (3) The combined winding structure proposed in this invention can generate the same torque as the original stator winding structure, while reducing resistance and copper loss and improving motor efficiency; in addition, under the premise of the same copper loss, it can effectively increase torque.

[0030] (4) Compared with other combined winding schemes, the present invention has lower requirements for windings and has broad application prospects. Attached Figure Description

[0031] Figure 1 This is a flowchart of a design method for a combined winding structure of a brushless dual-rotor motor proposed in this invention.

[0032] Figure 2 This is an example of the back electromotive force FFT result of a modulation winding and torque winding under no-load conditions with pole-slot combination provided in one embodiment of the present invention.

[0033] Figure 3 This is a star diagram of the slot potential with 24 slots and 8 pole pairs provided in one embodiment of the present invention.

[0034] Figure 4 This is a star diagram of the slot potential with 24 slots and 11 pole pairs provided in one embodiment of the present invention.

[0035] Figure 5 This is a connection diagram of a three-phase coil with 24 slots and 8 pole pairs provided in one embodiment of the present invention.

[0036] Figure 6 This is a connection diagram of a three-phase coil with 24 slots and 11 pole pairs provided in one embodiment of the present invention.

[0037] Figure 7(a) is a schematic diagram of a coil wound on the same tooth and with the same energizing direction provided in one embodiment of the present invention.

[0038] Figure 7(b) is a schematic diagram of a coil that is wound on the same tooth and has the same energizing direction provided in one embodiment of the present invention.

[0039] Figure 8 This is a schematic diagram of a novel combined winding structure provided in one embodiment of the present invention.

[0040] Figure 9 This is a comparison diagram of the no-load back electromotive force of the modulation winding A phase in a novel combined winding structure and a non-combined winding structure provided in one embodiment of the present invention.

[0041] Figure 10 This is a comparison diagram of the no-load back electromotive force of phase A of the torque winding in a new combined winding structure and a non-combined winding structure provided in one embodiment of the present invention.

[0042] Figure 11 This is a comparison diagram of the inner and outer rotor torques under a new combined winding structure and an uncombined winding structure provided in one embodiment of the present invention.

[0043] Figure 12 This is a schematic diagram of a combined winding structure provided in one embodiment of the present invention. Detailed Implementation

[0044] The embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0045] This invention addresses the shortcomings of existing combined winding structures, which are still more complex than conventional windings and have a narrower application range. It proposes a design method for a combined winding structure in a brushless dual-rotor motor. The flowchart of this method is as follows: Figure 1 As shown, it includes steps 1 to 6.

[0046] Step 1: Determine the range of the pole pair ratio based on the rated torque.

[0047] In one example, the outer rotor of the brushless dual-rotor motor is connected to the wheel via a reduction gear, while the inner rotor is connected to the engine crankshaft. Torque data suitable for the hybrid system was obtained through experiments and calculations. With appropriate scaling, the rated torque of the outer rotor was ultimately determined to be 63 Nm, the rated torque of the inner rotor to be -31.2 Nm, the rated speed of the outer rotor to be 3000 rpm, and the rated speed of the inner rotor to be 1500 rpm.

[0048] A brushless dual-rotor motor can be considered as a flux modulation motor coupled with a permanent magnet synchronous motor. The ratio of the inner and outer rotor torques of the modulation motor is shown in equation (1).

[0049] (1)

[0050] In equation (1), To modulate the rotor torque inside the motor, To modulate the torque of the motor's external rotor, This refers to the number of pole pairs of the permanent magnets in the inner rotor of a brushless dual-rotor motor. This refers to the number of magnetic blocks on the outer rotor of a brushless dual-rotor motor.

[0051] In addition, in a brushless dual rotor motor, when the motor is in its rated operating state, both windings output positive force to the external rotor, while the rated torque of the internal rotor is entirely provided by the modulation winding. The expressions for the rated torque of the internal and external rotors are shown in equations (2)-(3).

[0052] (2)

[0053] (3)

[0054] In equations (2)-(3), The rated torque of the inner rotor of the brushless dual-rotor motor is... The rated torque of the outer rotor of the brushless dual-rotor motor is... This represents the torque on the outer rotor of the permanent magnet synchronous motor.

[0055] Based on equations (1)-(3), the relationship between the number of pole pairs of the inner and outer rotors and the rated torque of the inner and outer rotors of the brushless dual rotor motor can be deduced, as shown in equation (4).

[0056] (4)

[0057] Substituting the rated torque of the inner and outer rotors mentioned above, the range of the number of pole pairs of the inner and outer rotors will be limited, as shown in equation (5).

[0058] (5)

[0059] Furthermore, bidirectional magnetization is considered for the outer rotor here, therefore the number of pole pairs of the outer rotor magnets and the number of pole pairs of the outer rotor magnetic blocks are as shown in equation (6), where, This refers to the number of permanent magnet pole pairs on the outer rotor of a brushless dual-rotor motor.

[0060] (6)

[0061] Step 2: Exhaustively enumerate all pole-slot combinations based on the winding factor.

[0062] The back electromotive force generated on one side of the coil As shown in equation (7), where The rotational speed is the physical rotational speed of the magnetic field. This represents the magnetic field amplitude. This is the axial length of the iron core. The inner radius of the stator. This represents the number of turns in the coil.

[0063] (7)

[0064] Therefore, the no-load electromotive force generated in one phase As shown in equation (8), where This represents the total number of coil groups in a single phase winding. Let P1 be the magnetic field electrical angle corresponding to coil j with pole pairs P1. It is the electrical angle of the magnetic field with a pole pair number of P1 corresponding to the span. Considering the use of concentrated windings, therefore... It is the electrical angle with a span of one tooth.

[0065] (8)

[0066] Therefore, the self-winding factor can be defined as shown in equation (9), while the mutual winding factor can be defined as the winding coefficient corresponding to a single pole pair with a number of P2 in space under the winding combination with Q slots and P1 pole pairs. That is, the mutual winding factor can be defined as shown in equation (10), where Let P2 be the magnetic field electrical angle corresponding to coil j with a pole pair number of P2. It is the electric angle of the magnetic field with a span of P2 corresponding to one tooth.

[0067] (9)

[0068] (10)

[0069] After defining the self-winding factor and mutual winding factor, considering that the self-winding factor is higher than 0.6 and the mutual winding factor is lower than 0.1, and based on the stator outer diameter, considering the maximum limit of the slot number Q, Q is ultimately limited to within 48. Finally, a batch of pole-slot combinations with high self-winding factors, low mutual winding factors, and satisfying the range of the ratio of the number of outer rotor magnetic blocks to the number of inner rotor pole pairs is exhaustively screened. It should be noted that the main magnetic fields in the outer air gap are: the modulation magnetic field, the fundamental wave of the inner rotor permanent magnet magnetic field, the fundamental wave of the outer rotor permanent magnet magnetic field, and the third harmonic of the outer rotor permanent magnet magnetic field. Therefore, for any set of stator windings, there is one self-winding factor and three mutual winding factors during the screening process, which further narrows the exhaustive range without significantly increasing the computational load.

[0070] In one embodiment of the present invention, partial results of pole-slot fits satisfying rated torque and winding coefficients, as shown in Table 1, are provided, wherein... The number of pole pairs for modulating the magnetic field is given; other variables have been defined previously.

[0071] Table 1

[0072]

[0073] Step 3: Establish a finite element model and further filter it using Fast Fourier Transform (FFT).

[0074] This embodiment uses the finite element method software Ansys Maxwell to build a brushless dual-rotor motor model for simulation. Simulation parameters are set, including motor geometry, material properties, and boundary conditions. In this example, the motor outer diameter is set to 220mm, the inner diameter to 155mm, the air gap to 0.75mm, the permanent magnet material to be N45, and the ferromagnetic material to be M19_29. The total simulation time is set to [missing information]. ,in, The internal rotor speed, Let be the external rotor speed. Based on this, the simulation can maintain the same magnetic circuit at the start and end times, and the simulation step size is defined as... ,in To modulate the winding electrical frequency, This refers to the electrical frequency of the torque winding. After this round of screening, some pole-slot combinations with large harmonic back EMF of the winding under no-load conditions and which are not decoupled from each other have been eliminated.

[0075] In one embodiment of the present invention, Table 2 is provided to provide partial pole-slot matching results that satisfy the requirements of small harmonic back EMF of windings and mutual decoupling between windings after no-load simulation FFT analysis.

[0076] Table 2

[0077]

[0078] In one embodiment of the present invention, a method is provided. Figure 2 The image shows the back electromotive force (FFT) results of the modulation winding and torque winding under no-load conditions with a pole-slot combination. The number of slots is 24, the modulation winding has 8 pole pairs, and the torque winding has 11 pole pairs. Both windings are concentrated windings. The inner rotor permanent magnet has 14 pole pairs, the outer rotor permanent magnet has 11 pole pairs, and the outer rotor has 22 magnetic conductors. The results show that under the current pole-slot combination finite element model, the two windings exhibit few harmonics and are mutually decoupled.

[0079] Step 4: Rearrange the winding sequence and select the pole-slot combination with the highest winding combination ratio.

[0080] In one embodiment of the present invention, a method is provided. Figure 3 , Figure 4 The diagram shown is a star-shaped diagram of the tank potential, in which... Figure 3 For a pole-slot configuration with 24 slots and 8 pole pairs, Figure 4 It is a pole-slot combination with 24 slots and 11 pole pairs.

[0081] In one embodiment of the present invention, a method is provided. Figure 5 , Figure 6 The three-phase coil connection diagram shown is as follows: Figure 5 For a pole-slot configuration with 24 slots and 8 pole pairs, Figure 6It is a pole-slot combination with 24 slots and 11 pole pairs.

[0082] In one embodiment of the present invention, a schematic diagram of a coil wound on the same stator tooth and energized in the same direction, as shown in FIG7(a), is provided.

[0083] Based on the star diagram of the electromotive force of the slot conductors under the 60-degree phase band division, the slot conductors located under the A+, B+, C+ and A-, B-, C- phase bands are selected, and the first slot conductor of the two sets of windings located under the A+ phase band is transferred to the first slot, and the other slot conductors are transferred in the same way.

[0084] Figure 3 , Figure 4 This involves transferring the first slot conductor of both windings located under the A+ phase band to the first slot, and then similarly arranging the other slot conductors in the same way to create a new winding sequence. Based on this new winding sequence, new winding coil connection methods can be generated, such as... Figure 5 , Figure 6 As shown in Figure 7(a). By statistically analyzing the percentage of coils satisfying the form in the newly arranged winding sequence, the pole-slot combinations selected in step 3 can be sorted. The winding combination rate K is defined as shown in equation (11), where This represents the total number of coils that can be merged.

[0085] (11)

[0086] Ultimately, a pole-slot combination with 8 slots and 8 and 11 pole pairs was selected. This pole-slot combination has the highest winding combination rate, with K reaching 1 / 4.

[0087] Step 5: Combine coils wound on the same tooth, with the same energizing direction and the same number of turns.

[0088] In one embodiment of the invention, a schematic diagram of a coil wound on the same tooth and energized in the same direction, as shown in FIG7(b), is provided.

[0089] For coils wound on the same tooth, with the same energizing direction and the same number of turns, since they are in the same spatial position and have the same number of turns, the expression for the coil electromotive force under no-load conditions is as shown in equation (7).

[0090] Additionally, when the first coil is energized The second coil is energized. At that time, it will sense in the space The magnetic field magnetomotive force means that if the magnetic field magnetomotive force is... If a current is passed through an N-turn coil, the induced magnetic field and magnetomotive force will be the same.

[0091] In conclusion, it can be considered as one The coil of turns replaces the original coil, and... , The current is fed into the new coil along with the original current. It's also important to note that since the total number of turns is halved, the cross-sectional area of ​​the conductor can be doubled, which reduces copper losses while maintaining the same torque. Undoubtedly, the copper losses of the original coil are: ,in The resistance of the coil will be increased, while the copper loss of the newly synthesized coil will become... The copper loss of the new coil will be reduced to half of the original copper loss.

[0092] Figures 7(a) and 7(b) illustrate the coil energizing methods before and after merging. As mentioned above, the two winding structures will produce the same effect. This winding has 24 slots and 8 and 11 pole pairs. Based on the new winding sequence generated in step 4, according to... Figure 5 , Figure 6 The coils that can be merged are coils 1, 16, 9, 24, 8, and 17. Therefore, these coils should be merged one by one.

[0093] Step 6: Generate a combined winding structure by connecting series and parallel windings.

[0094] In one embodiment of the present invention, a method is provided. Figure 8 The diagram shows the new combined winding structure.

[0095] After merging the coils in step 5, the original windings are divided into three parts: the unmerged A, B, and C phases of the first winding; the unmerged A, B, and C phases of the second winding; and the merged A, B, and C phases of the first and second windings. To avoid circulating current, the merged A, B, and C phases are placed at the end of the circuit. The ends of the unmerged A, B, and C phases of the first and second windings are connected to the beginning of the merged A, B, and C phases in phase sequence. This design prevents circulating current. Finally, a new merged winding structure is generated, and the copper loss of the new merged winding structure is... As shown in equation (12)

[0096] (12)

[0097] in This refers to the copper loss of the original coil.

[0098] like Figure 8 As shown, the final coils 1, 16, 9, 24, 8, and 17 after merging are placed at the end of the circuit, while the other coils are connected as originally. It should be noted that the first part in the figure is the unmerged part of the modulation winding, the second part is the unmerged part of the torque winding, and the third part is the part after the two sets of windings are merged.

[0099] In one embodiment of the present invention, a method is provided. Figure 9 The diagram shows a comparison of the no-load back EMF of phase A of the modulation winding under the new combined winding structure and the no-load back EMF of phase A of the modulation winding under the non-combined winding structure.

[0100] In one embodiment of the present invention, a method is provided. Figure 10 The diagram shows a comparison of the no-load back EMF of phase A of the torque winding under the new combined winding structure and the no-load back EMF of phase A of the torque winding under the non-combined winding structure.

[0101] In one embodiment of the present invention, a method is provided. Figure 11 The diagram shows a comparison of the inner and outer rotor torques under the new combined winding structure and the inner and outer rotor torques under the non-combined winding structure.

[0102] Figure 9 and Figure 10 A comparison diagram of the no-load back EMF of phase A in the new combined winding structure and the non-combined winding structure is shown. The first part of the EMF represents the no-load back EMF of phase A in the non-combined portion of the modulation winding; the second part represents the no-load back EMF of phase A in the non-combined portion of the torque winding; and the third part represents the no-load back EMF of phase A in the combined portion of the modulation and torque windings. As can be seen from the diagram, the first part plus the third part of the EMF coincides with the original phase A EMF of the modulation winding, while the second part plus the third part of the EMF coincides with the original phase A EMF of the torque winding. This demonstrates the effectiveness of merging the coils in step 5.

[0103] Figure 11 This is a comparison diagram of the inner and outer rotor torques before and after the windings are merged. From... Figure 11 As can be seen, the outer and inner rotor torques under the new winding structure are the same as those under the original winding structure, which further proves the effectiveness of the merged windings.

[0104] The combined winding structure of the brushless dual-rotor motor obtained by the design method proposed in this invention is as follows: Figure 12 As shown, it includes: the unmerged part of the first set of windings, the unmerged part of the second set of windings, and the merged winding. The ends of the unmerged parts of the two sets of windings are connected in series with the first section of the merged winding in phase sequence. The ends of the merged winding are connected in a star configuration. Three-phase current is passed through the first section of the unmerged parts of the two sets of windings.

Claims

1. A design method for a combined winding structure of a brushless dual-rotor motor, characterized in that, include: Step 1: Determine the range of the ratio of the number of magnetic blocks of the outer rotor to the number of pole pairs of the inner rotor based on the rated torque of the inner and outer rotors. Step 2: Based on the stator winding concentrated winding design, and considering the high self-winding factor and low mutual winding factor, exhaustively search all pole slot combinations under the constraint of the ratio of the number of outer rotor magnetic blocks to the number of inner rotor pole pairs. Step 3: Perform FFT analysis on the back electromotive force of the two windings under all pole-slot combinations exhaustively listed in Step 2, and screen out the pole-slot combinations that meet the decoupling control requirements. Step 4: For the pole slot combinations selected in Step 3, rearrange the sequence of the two sets of windings under each pole slot combination, and select the pole slot combinations whose winding combination rate reaches the threshold. Step 5: For the two sets of windings with the highest winding combination rate under the pole-slot combination, combine the coils wound on the same stator tooth, with the same energizing direction and the same number of turns. Step 6: Connect the unmerged portions of the two sets of windings in series and parallel, as well as the merged winding, to obtain a merged winding structure in which the circulating current meets the design specifications.

2. The design method for a combined winding structure of a brushless dual-rotor motor according to claim 1, characterized in that, The specific method for determining the range of the ratio of the number of magnetic blocks of the outer rotor to the number of pole pairs of the inner rotor based on the rated torque of the inner and outer rotors in step 1 is as follows: Considering that when the brushless dual-rotor motor is in its rated operating state, both sets of windings output positive force to the outer rotor, while the rated torque of the inner rotor is entirely provided by the modulation winding, the brushless dual-rotor motor is regarded as a flux modulation motor coupled with a permanent magnet synchronous motor. Determine the range of the ratio of the number of magnetic blocks in the outer rotor to the number of pole pairs in the inner rotor, where, This refers to the number of magnetic blocks on the outer rotor of a brushless dual-rotor motor. This refers to the number of rotor pole pairs in a brushless dual-rotor motor. , The rated torque of the inner and outer rotors of the brushless dual-rotor motor. , The number of permanent magnet pole pairs on the outer rotor of a brushless dual-rotor motor. , , , To modulate the torque of the inner and outer rotors of the motor, This represents the torque on the outer rotor of the permanent magnet synchronous motor.

3. The design method for a combined winding structure of a brushless dual-rotor motor according to claim 2, characterized in that, The specific method for exhaustively searching all pole-slot combinations under the constraint of the ratio range of the number of pole pairs between the outer rotor magnetic block and the inner rotor in step 2 is as follows: Define the self-winding factor. With mutual winding factor as follows: , ,in, This represents the total number of coil groups in a single phase winding. represents an imaginary number, for The magnetic field electric angle corresponding to coil number P1 is P1. Let P1 be the electric angle of the magnetic field corresponding to a pole pair number P1 under a span of one stator tooth. for The magnetic field electric angle corresponding to coil number P2 is P2. The electrical angle of the magnetic field with a span of P2 corresponding to one stator tooth and a pole pair number of P2 is given by the stator outer diameter, which limits the total number of slots. The maximum value is used to select pole slot combinations with a self-winding factor higher than 0.6 and a mutual winding factor lower than 0.1, under the constraint of the ratio range of the number of pole pairs of the outer rotor magnetic block and the inner rotor.

4. The design method for a combined winding structure of a brushless dual-rotor motor according to claim 3, characterized in that, In step 3, the back electromotive force of the two windings under all pole-slot combinations exhaustively listed in step 2 is analyzed by FFT. The specific method for screening pole-slot combinations that meet the decoupling control requirements is as follows: the no-load back electromotive force of the two windings under all pole-slot combinations exhaustively listed in step 2 is analyzed by FFT. The pole-slot combinations corresponding to the no-load back electromotive force harmonics exceeding the threshold and the two windings not being decoupled from each other are discarded.

5. The design method for a combined winding structure of a brushless dual-rotor motor according to claim 4, characterized in that, The specific method of step 4 is as follows: For the two sets of windings under each pole slot combination selected in step 3, based on the slot conductor electromotive force star diagram under the 60-degree phase band division, the slot conductors located under the A+, B+, C+ and A-, B-, C- phase bands are selected, and the slot conductors of the two sets of windings located under the same phase band are transferred to one slot. The coils wound on the same stator tooth and with the same energizing direction are called merging coils. After counting the total number of merging coils of the two sets of windings, the winding merging rate is calculated. , ,in, To determine the total number of coils that can be combined between the two sets of windings, select pole-slot combinations where the winding combination rate reaches a threshold.

6. The design method for a combined winding structure of a brushless dual-rotor motor according to claim 5, characterized in that, The specific method for merging coils in step 5 is as follows: For coils wound on the same toothed stator, with the same energizing direction and the same number of turns, a new coil is used to replace the coils wound on the same toothed stator, with the same energizing direction and the same number of turns in the two sets of windings. The cross-sectional area of ​​the new coil is twice the cross-sectional area of ​​a single-turn coil in the two sets of windings, and the number of turns of the new coil is the same as the number of turns of the coil in the original set of windings.

7. The design method for a combined winding structure of a brushless dual-rotor motor according to claim 6, characterized in that, The specific method for connecting the unmerged portions of the two sets of windings in series and parallel in step 6, as well as the merged winding, is as follows: connect the ends of the unmerged portions of the two sets of windings in series with the first segment of the merged winding in phase sequence, and connect the ends of the merged winding in a star or delta configuration.

8. A combined winding structure for a brushless dual-rotor motor, characterized in that, The merging winding structure obtained by using the design method described in any one of claims 1 to 7 includes: a first set of unmerged windings, a second set of unmerged windings, and a merged winding. The ends of the unmerged parts of the two sets of windings are respectively connected in series with the first segment of the merged winding in phase sequence. The ends of the merged winding are connected in a star or delta configuration. Three-phase current is passed through the first segment of the unmerged parts of the two sets of windings.

9. A stator structure for a brushless dual-rotor motor, comprising: A set of modulation windings, a set of torque windings, and a stator, characterized in that the set of modulation windings and the set of torque windings are the combined winding structure as described in claim 8, and the combined winding structure is wound on the stator.

10. A brushless dual-rotor motor, comprising an inner rotor and an outer rotor, characterized in that, The brushless dual-rotor motor also includes the stator structure as described in claim 9, wherein the inner rotor, outer rotor, and stator structure are concentrically nested.

Images