Double-winding double-speed motor wiring method and positive-pressure shell type three-phase asynchronous motor

Abstract

The invention discloses a double-winding double-speed motor wiring method and a positive-pressure shell type three-phase asynchronous motor, and relates to the technical field of motor design and electrical control. In order to solve the problems that in the prior art, when a double-winding double-speed motor operates at different pole numbers, the efficiency of the motor is reduced, the temperature rise is increased, and the operation performance is unstable, two sets of independent three-phase symmetrical windings are arranged in a motor stator and correspond to the operation states of different pole pair numbers respectively; determining a winding pole pitch and a slot pitch angle according to the relationship between the number of stator slots and the number of pole pairs, and arranging the two sets of windings in the stator slots in a mutually staggered and embedded manner; in the electromagnetic design stage, the induced potentials of the non-working windings are mutually counteracted; in the parallel winding design, the number of branches and the connection sequence are optimized to eliminate parallel circulating current; and independent access and safe switching of different windings are realized through the wiring terminal box and the control system. The method is suitable for design and manufacturing of the positive-pressure shell type double-winding double-speed asynchronous motor.

Description

Technical Field

[0001] This invention relates to the fields of motor design and electrical control technology, and in particular to a wiring and circulating current suppression technology for a positive-pressure housing type dual-winding dual-speed asynchronous motor. Background Technology

[0002] Currently, dual-winding dual-speed motors are widely used in industrial equipment such as cranes, mining equipment, fans, and pumps. They can switch between two speeds under different loads and operating conditions, balancing energy efficiency and reliability, making them a common type of motor in high-performance drive systems. Existing dual-speed motors typically achieve pole-changing speed regulation by placing two independent three-phase symmetrical windings in the stator. When one winding is working, the other is in a non-working state to adapt to different speed and torque requirements. However, with the continuous increase in motor capacity and the increasing complexity of application conditions, the traditional single-winding connection method is gradually revealing performance bottlenecks under high power and multi-parallel branch conditions.

[0003] In existing technologies, some researchers have proposed reducing the induced electromotive force in the non-working windings by optimizing electromagnetic design or winding arrangement. For example, existing solutions use methods such as changing the winding pole pitch, phase band width, or adjusting the slot ratio to reduce magnetomotive force harmonics; others limit the circulating current amplitude by adding damping circuits, resistor compensation, or electronic control components at the control end. However, these solutions often suffer from drawbacks such as complex implementation, high cost, or inability to fundamentally eliminate circulating currents. Especially in positive-pressure housing type dual-winding dual-speed motors, because the two sets of windings are arranged independently and have stronger electromagnetic coupling, if the wiring method is unreasonable, a large circulating current will be generated in the non-working windings due to induced electromotive force. This not only leads to stator heating and efficiency reduction but also causes air gap magnetic field distortion and additional torque, thereby reducing the motor's operating stability and service life.

[0004] In summary, existing technologies have the drawback that when dual-winding dual-speed motors operate at different pole numbers, circulating currents are generated in the non-working windings due to improper wiring, leading to reduced motor efficiency, increased temperature rise, and unstable operating performance. Summary of the Invention

[0005] To address the shortcomings of existing dual-winding dual-speed motors, where improper wiring in the non-working windings generates circulating currents, leading to reduced motor efficiency, increased temperature rise, and unstable operating performance when operating at different pole numbers, the present invention provides the following technical solution: A wiring method for a dual-winding, dual-speed motor includes the following steps: Two independent three-phase symmetrical windings are set in the motor stator, corresponding to different operating states with different numbers of pole pairs; Based on the correspondence between the number of stator slots and the number of pole pairs, the pole pitch and slot pitch angle of each winding are determined, and the two sets of windings are arranged in stator slots in a staggered manner so that the two sets of windings are spatially separated and electrically isolated from each other. During the electromagnetic design phase, the conditions for the formation of circulating current under different pole numbers are analyzed to determine the phase difference distribution of the induced electromotive force of each pole phase group in the other winding when one winding is energized. Based on the phase difference distribution results, the wiring method of the winding is determined so that the induced electromotive forces of adjacent pole phase groups in the non-working winding are opposite in direction and cancel each other out. In the connection design of parallel windings, the number of parallel branches and the connection sequence of each phase winding are determined so that the induced electromotive force in each parallel branch is in the same direction and the electromotive forces between each branch cancel each other out. By using a terminal box, windings with different pole pairs are independently connected, and the control system selectively connects the corresponding windings, so that only one set of windings is energized during the switching process.

[0006] Furthermore, a preferred embodiment is provided in which two sets of three-phase symmetrical windings are respectively connected in a Y-shape, each phase winding is composed of several coils connected in series, and the electrical angle between the three phase windings differs by 120 degrees.

[0007] Furthermore, a preferred embodiment is provided in which, in the two sets of three-phase symmetrical windings, the upper coil of one set of windings is located between the lower coils of the other set of windings.

[0008] Furthermore, a preferred embodiment is provided, wherein the determination of the winding connection method includes establishing an induced electromotive force vector distribution model and calculating and determining the connection sequence based on the phase difference of the electromotive force of each phase group, so that the combined electromotive force of each phase is zero.

[0009] Furthermore, a preferred embodiment is provided in which, in the parallel winding design, when two or more parallel circuits are used, the connection points of each parallel branch are staggered so that the induced electromotive force in adjacent branches is in opposite directions.

[0010] Furthermore, a preferred embodiment is provided in which the selection of the coil span is based on the air gap magnetic flux density distribution analysis results, and the harmonic magnetomotive force generated by the working winding is reduced by adjusting the span.

[0011] Based on the same inventive concept, the present invention also provides a positive pressure housing type three-phase asynchronous motor, which is wired by the method described above, including a motor housing, stator, rotor, terminal box and control system; The motor housing is a positive pressure explosion-proof structure, and the inside of the housing maintains a slightly positive pressure higher than that of the external environment; The stator has two independent three-phase symmetrical windings, which correspond to different operating states with different numbers of pole pairs, to achieve dual-speed operation; Two independent three-phase symmetrical windings are arranged in stator slots in a staggered manner and are electrically isolated from each other; In a three-phase symmetrical winding, the induced electromotive forces of each pole phase group of the non-working winding are in opposite directions and cancel each other out. The terminal box is equipped with two sets of independent three-phase input terminals and star terminals corresponding to two sets of three-phase symmetrical windings. The control system is used to selectively connect different windings to achieve dual-speed switching. The control system is used to ensure that the two sets of windings are not energized at the same time during the switching process; The rotor generates a rotating magnetic field through electromagnetic coupling with the stator magnetic field; The motor is equipped with a cooling system to reduce the temperature rise of the stator windings.

[0012] Based on the same inventive concept, the present invention also provides a computer storage medium for storing a computer program, wherein when the computer program is read by a computer, the computer executes the method described thereon.

[0013] Based on the same inventive concept, the present invention also provides a computer, including a processor and a storage medium, wherein when the processor reads a computer program stored in the storage medium, the computer executes the method described thereon.

[0014] Based on the same inventive concept, the present invention also provides a computer program product, which, when executed, implements the method described.

[0015] Compared with the prior art, the advantages of the technical solution provided by the present invention are as follows: This solution analyzes circulating currents under different pole numbers during the motor electromagnetic design phase to determine the phase difference relationship of the induced electromotive force in the non-working windings under 4-pole and 6-pole operating conditions. This guides the selection of wiring methods, ensuring that the combined electromotive force of each branch is zero. The advantage of this method is that it avoids the formation of circulating currents from the design stage. Compared to existing technologies that rely on external damping resistors or additional circuits to suppress circulating currents, this solution achieves self-cancellation of electromotive force through wiring methods. It has a simpler structure, higher reliability, and avoids energy loss and maintenance problems caused by additional components.

[0016] This solution employs a reasonable number of parallel branches and coil connection sequence to ensure that the induced electromotive forces in the branches of the non-working winding cancel each other out, thereby effectively weakening or eliminating circulating current paths. This results in a significant reduction in the induced current in the non-working winding, leading to a decrease in stator temperature rise, improved operating efficiency, and more stable long-term motor operation. Compared to existing technologies that simply rely on changing the winding pole pitch or phase band angle to weaken harmonic magnetomotive forces, this solution can completely eliminate circulating currents without altering the stator structure, making it more versatile.

[0017] This design weakens the harmonic magnetomotive force generated by the working winding in the air gap by selecting an appropriate winding pitch, while simultaneously reducing the cutting effect of this magnetomotive force on the other non-working winding. This effectively reduces electromagnetic coupling between the stators, weakens the distortion of the air gap magnetic field, and makes the motor's performance more stable under dual-speed operation. Compared to traditional methods that compensate for harmonics by adjusting coil pitch, this design considers the mutual influence between the two windings, resulting in a more symmetrical magnetic field distribution and thus superior electromagnetic performance.

[0018] The wiring method for the dual-winding motor in this solution is simple, employing the common phase-winding connection method with a small number of jumpers. This approach simplifies motor manufacturing and installation processes, reduces potential risks from wiring errors, and improves the repeatability and consistency of on-site assembly. Compared to dual-speed motor solutions that rely on complex wiring or distributed control modules, this solution achieves both improved reliability and economy without increasing manufacturing costs.

[0019] This solution optimizes the wiring method and branch configuration, enabling the motor to maintain good performance at different speeds. This expands the applicability of the dual-speed motor and improves its operational stability and efficiency under high starting loads and high-frequency switching conditions. Compared to traditional solutions, this solution ensures high torque output at low speeds while avoiding heat generation and additional losses at high speeds, significantly improving the overall performance of the positive-pressure housing type dual-winding dual-speed motor.

[0020] This is applicable to the design and manufacture of positive-pressure housing type double-winding dual-speed asynchronous motors that require reliable variable speed drive under different loads or operating conditions. Attached Figure Description

[0021] Figure 1 A schematic diagram of the first connection method for the 4P winding when running with 6P; Figure 2 A schematic diagram of the second connection method for the 4P winding when running with 6P; Figure 3 A schematic diagram of the first connection method for the 6P winding when operating with 4P; Figure 4 A schematic diagram of the second connection method for the 6P winding when operating with 4P; Figure 5 This is a schematic diagram of the third connection method for the 6P winding when operating with 4P. Detailed Implementation

[0022] To make the advantages and benefits of the technical solution provided by the present invention clearer, the technical solution provided by the present invention will now be described in further detail with reference to the accompanying drawings, specifically: Implementation Method 1: This implementation method provides a wiring method for a dual-winding, dual-speed motor, including the following steps: Two independent three-phase symmetrical windings are set in the motor stator, corresponding to different operating states with different numbers of pole pairs; Based on the correspondence between the number of stator slots and the number of pole pairs, the pole pitch and slot pitch angle of each winding are determined, and the two sets of windings are arranged in stator slots in a staggered manner so that the two sets of windings are spatially separated and electrically isolated from each other. During the electromagnetic design phase, the conditions for the formation of circulating current under different pole numbers are analyzed to determine the phase difference distribution of the induced electromotive force of each pole phase group in the other winding when one winding is energized. Based on the phase difference distribution results, the wiring method of the winding is determined so that the induced electromotive forces of adjacent pole phase groups in the non-working winding are opposite in direction and cancel each other out. In the connection design of parallel windings, the number of parallel branches and the connection sequence of each phase winding are determined so that the induced electromotive force in each parallel branch is in the same direction and the electromotive forces between each branch cancel each other out. By using a terminal box, windings with different pole pairs are independently connected, and the control system selectively connects the corresponding windings, so that only one set of windings is energized during the switching process.

[0023] The two sets of three-phase symmetrical windings are connected in a Y-shape. Each phase winding consists of several coils connected in series, and the electrical angle between the three phase windings differs by 120 degrees.

[0024] In two sets of three-phase symmetrical windings, the upper coil of one set of windings is located between the lower coils of the other set of windings.

[0025] The determination of the winding connection method includes establishing an induced electromotive force vector distribution model and calculating the connection sequence based on the phase difference of the electromotive force of each phase group, so that the combined electromotive force of each phase is zero.

[0026] In parallel winding design, when two or more parallel circuits are used, the connection points of each parallel branch are staggered so that the induced electromotive force in adjacent branches is in opposite directions.

[0027] The selection of the coil span is based on the analysis results of the air gap magnetic flux density distribution. The harmonic magnetomotive force generated by the working winding is reduced by adjusting the span.

[0028] A positive-pressure housing type three-phase asynchronous motor is also provided, which is wired by the method described above, including a motor housing, stator, rotor, terminal box and control system; The motor housing is a positive pressure explosion-proof structure, and the inside of the housing maintains a slightly positive pressure higher than that of the external environment; The stator has two independent three-phase symmetrical windings, which correspond to different operating states with different numbers of pole pairs, to achieve dual-speed operation; Two independent three-phase symmetrical windings are arranged in stator slots in a staggered manner and are electrically isolated from each other; In a three-phase symmetrical winding, the induced electromotive forces of each pole phase group of the non-working winding are in opposite directions and cancel each other out. The terminal box is equipped with two sets of independent three-phase input terminals and star terminals corresponding to two sets of three-phase symmetrical windings. The control system is used to selectively connect different windings to achieve dual-speed switching. The control system is used to ensure that the two sets of windings are not energized at the same time during the switching process; The rotor generates a rotating magnetic field through electromagnetic coupling with the stator magnetic field; The motor is equipped with a cooling system to reduce the temperature rise of the stator windings.

[0029] A computer storage medium is also provided for storing a computer program, which, when read by the computer, executes the method.

[0030] A computer is also provided, including a processor and a storage medium, wherein the computer executes the method when the processor reads a computer program stored in the storage medium.

[0031] A computer program product is also provided, which, when executed, implements the method described.

[0032] Implementation Method Two: This implementation method is a further detailed description of the technical solution provided in Implementation Method One, specifically: A wiring method for a dual-winding, dual-speed motor and an implementation method for a pressure-enclosed three-phase asynchronous motor include the following steps. First, based on the operational requirements of the target equipment, the motor's power rating, number of pole pairs, and voltage rating are determined. Combining this with the characteristics of the pressure-enclosed protective structure, the basic design parameters of the motor are established. Taking the YDZYK type motor as an example, its rated power is 560 kW and 315 kW, its rated voltage is 6 kV, its frequency is 50 Hz, and its stator slots are 72. When operating with 4 poles, the pole pitch is 18, the slot pitch angle is 10 degrees, and the number of slots per pole per phase is 6; when operating with 6 poles, the pole pitch is 12, the slot pitch angle is 15 degrees, and the number of slots per pole per phase is 4. Determining these basic parameters provides input data for the winding pole pitch arrangement, coil pitch, and phase distribution.

[0033] Secondly, two independent three-phase symmetrical windings are arranged in the stator core slots to form a double-winding structure. Based on the relationship between the number of stator slots and the number of pole pairs, the arrangement of 4-pole and 6-pole windings is designed respectively. The two sets of windings are physically staggered but electrically completely isolated. Each set of windings adopts a double-layer lap winding form to ensure uniform distribution and consistent phase sequence. To achieve electromagnetic compatibility and uniform air gap magnetic field distribution, the upper and lower slots of the windings are arranged alternately, making the spatial composite waveform of the magnetomotive force of each phase approach a sine wave, improving the electromagnetic balance of the motor in dual-speed mode. This step outputs a detailed slot allocation table and winding phase sequence table, laying the foundation for subsequent circulating current analysis.

[0034] Then, the circulating current distribution under different pole numbers is analyzed during the electromagnetic design phase. Since the motor has a dual-winding structure, when one set of windings is energized, its rotating magnetic field cuts the other non-working winding, inducing an electromotive force (EMF) in the non-working winding. Taking a 6-pole operating state as an example, the fundamental magnetomotive force generated by the working winding rotates at a 6-pole speed, generating an EMF distribution relative to the stator; at this time, the 4-pole winding acts as a closed loop, generating an induced EMF due to the spatial phase difference. Based on the slot pitch angle and pole ratio, the phase difference between adjacent pole phase groups can be calculated to be 270 degrees. For ease of analysis, the pole phase group of the 4-pole winding is divided into several subgroups. Assuming that the induced EMF amplitude of each subgroup is the same, the potential directions between adjacent pole phase groups differ by 90 degrees. If the winding connection sequence is improper, the induced EMF vector cannot be completely canceled out, thus forming a closed circulating current, leading to increased motor temperature and losses.

[0035] After determining the circulating current distribution, the influence of different wiring methods on the formation of circulating current is analyzed. Taking a 4-pole winding as an example, when the motor is running with 6 poles, there are several possible wiring methods. By establishing the potential synthesis relationship, it can be found that the total induced electromotive force under the first wiring method is the superposition of two sets of in-phase electromotive forces and two sets of out-of-phase electromotive forces, and the vector sum is not zero, resulting in circulating current. The second wiring method connects the pole phase groups in a phase-interleaved manner, so that the electromotive forces of the in-phase branches cancel each other out, the synthesized electromotive force is zero, and no circulating current is formed. Similarly, when the motor is running with 4 poles, the phase difference between the pole phase groups of the 6-pole winding is 120 degrees. If a conventional connection method is used, the synthesized electromotive force is not zero, and circulating current exists. By adjusting the connection sequence to make the induced electromotive forces between the branches symmetrical, the induced electromotive forces can be completely canceled out. The output of this process is the correct winding connection sequence and wiring topology, which can ensure that the synthesized electromotive force of the non-working winding is zero in any operating state.

[0036] Furthermore, the number and connection method of parallel branches are determined based on different motor capacities and application scenarios. Under high-capacity or high-load conditions, to reduce winding current density, each phase winding typically needs to be divided into two or more parallel circuits. In this case, the induced potential difference between parallel branches must be analyzed; improper connections can lead to circulating currents within the branches. This solution, by rationally selecting the tap point and connection sequence of each phase parallel branch, ensures that the potential phase of each branch remains consistent, and the induced potential vectors between branches cancel each other out, thereby completely eliminating the path for the formation of parallel circulating currents. The output is the optimal parallel branch configuration scheme, ensuring that the motor maintains good balance characteristics even with multiple branches in parallel.

[0037] After completing the winding connection design, the winding span and phase band angle were further optimized to weaken air gap magnetic field harmonics. While ensuring the synthesis of the main magnetic flux, the harmonic magnetomotive force generated by the working winding in the air gap was weakened by appropriately selecting the winding span, thereby reducing the cutting effect of this magnetomotive force on the non-working winding and decreasing the amplitude of the induced electromotive force. Unlike traditional methods that only adjust the pitch to weaken harmonics, this scheme comprehensively considers the electromagnetic coupling effect between the two windings, resulting in a more uniform magnetic field distribution and a smoother air gap magnetic flux density waveform, thus further improving the electromagnetic efficiency and operational stability of the motor.

[0038] Finally, the motor is manufactured and assembled according to the designed winding connection method and branch configuration. The two independent windings are wound into the specified slots and phase sequence, and connected at the terminals according to the determined phase sequence and connection method. After wiring, the motor undergoes insulation and withstand voltage tests. After assembly, the motor is tested under no-load, rated load, and different speed conditions to verify its current balance, temperature rise characteristics, and efficiency in 4-pole and 6-pole operation. Test results show that this solution can effectively eliminate the induced electromotive force and circulating current in the non-working windings, significantly reducing motor temperature rise and improving efficiency. Simultaneously, it maintains stable electromagnetic performance under starting and high-load operation, making it suitable for the design and manufacture of positive-pressure housing type dual-winding dual-speed motors with high reliability requirements.

[0039] A wiring method for a dual-winding dual-speed motor and an implementation method for a positive-pressure housing type three-phase asynchronous motor are as follows.

[0040] The overall structure of this motor includes a motor housing, stator, rotor, terminal box, and cooling system. The stator internally houses two independent three-phase symmetrical windings, each used to achieve different operating speeds. The rotor is a squirrel-cage structure, using copper bars and end rings cast together to form a closed conductive circuit, ensuring stable electromagnetic torque at different pole numbers. The housing employs a positive pressure explosion-proof structure, maintaining a slightly higher internal pressure than the external pressure to prevent flammable gases from entering the motor cavity. External air ducts and cooling fans are provided to reduce winding temperature rise and ensure safe and reliable long-term operation.

[0041] The stator is the core of the entire motor, with 72 slots. The stator core uses a laminated silicon steel sheet structure, externally fixed to the housing, with 72 slots evenly distributed internally. Two independent stator windings are installed within the stator, corresponding to 4-pole and 6-pole operation respectively. Both the 4-pole and 6-pole windings are double-layered, with the upper and lower coils spaced apart to ensure a uniform distribution of the air gap magnetic field and a near-sinusoidal magnetomotive force waveform. The two windings are Y-connected, with each phase winding consisting of multiple coils connected in series, each coil spanning a certain slot pitch to form a magnetic pole. By rationally allocating the slots, the two windings can be staggered in space, avoiding direct magnetic field overlap and minimizing electromagnetic coupling.

[0042] In terms of specific wiring structure, each phase coil of the 4-pole winding is distributed in 6 consecutive slots, with a pole pitch of 18 slot pitches and a slot pitch angle of 10 degrees. Each phase coil of the 6-pole winding is distributed in 4 consecutive slots, with a pole pitch of 12 slot pitches and a slot pitch angle of 15 degrees. To avoid complete overlap of the slot positions of the two sets of windings, the starting and ending slots of the windings are staggered, so that their respective magnetomotive forces form a phase interval in space. The three phase sequences of each winding are denoted as A, B, C and their reverse sequences X, Y, Z, to ensure that a three-phase symmetrical rotating magnetic field can be formed when energized.

[0043] The motor's terminal box contains two independent sets of terminals, corresponding to the 4-pole and 6-pole windings respectively. Each set of terminals includes a three-phase input terminal and a star terminal. The star terminal is sealed and not led out during operation, while the three-phase input terminal achieves dual-speed operation by selecting the energizing mode through the control system. The terminal box also contains a phase sequence indicator plate to indicate the phase sequence and corresponding slot number of each winding, preventing phase misalignment caused by incorrect wiring.

[0044] In terms of circuit structure, the control system includes a main power input circuit, a speed switching control circuit, a winding switching relay group, and a thermal protection module. The main power input circuit is connected to the power input terminal via a circuit breaker and a main contactor. The speed switching circuit connects either the 4-pole or 6-pole winding via control relays. To prevent short circuits or circulating currents during switching, the control system incorporates a mechanical and time interlock structure during the switching process, ensuring that one winding is completely de-energized before the other is allowed to be energized. The thermal protection module monitors the winding temperature in real time; when the temperature exceeds a set threshold, it automatically cuts off the power and issues an alarm signal to prevent overheating damage.

[0045] In operation, when the control system connects the 6-pole winding, the three-phase input terminals of the 6-pole winding receive symmetrical alternating current, forming a 6-pole rotating magnetic field. At this time, the non-working winding (4-pole winding) is subjected to the cutting effect of the rotating magnetic field, inducing an electromotive force (EMF) within it. To avoid circulating current in the non-working winding, this scheme determines a reasonable winding connection method through electromagnetic analysis during the design phase. In the 6-pole winding operation state, the 4-pole winding is connected in a specific sequence, causing the induced EMFs between adjacent pole phase groups to cancel each other out. Taking two parallel circuits per phase as an example, by connecting adjacent branches in a phase-interleaved manner, the induced EMF vectors of each branch can be made to have opposite directions, resulting in a zero composite EMF, thereby eliminating circulating current. Conversely, in the 4-pole winding operation state, the 6-pole winding connection method also adopts the same principle, causing the induced EMF vectors to cancel each other out and preventing the formation of a closed current path.

[0046] To further optimize the circulating current elimination effect, this scheme selects a reasonable winding span during stator design. The span selection is based on the air gap magnetic flux density distribution analysis results. By slightly adjusting the coil span, the harmonic magnetomotive force generated by the working winding in the air gap is weakened, thereby reducing the electromagnetic induction on the non-working winding. This reduces the amplitude of the induced electromotive force in the non-working winding on the one hand, and maintains the stability of the main magnetic flux on the other, thus improving the electromagnetic efficiency of the motor.

[0047] Furthermore, this solution optimizes the connection structure of parallel branches. To meet high power output requirements, windings typically employ a multi-branch parallel connection. By analyzing the induced potential distribution of each branch, the optimal parallel connection method is determined, ensuring that the potential direction in each branch is consistent and that the potentials between branches cancel each other out. With this connection method, no closed potential loop is formed inside the stator winding, fundamentally avoiding the problem of circulating current in the branches and significantly reducing the temperature rise of the motor under high load operation.

[0048] The system architecture also includes a cooling and protection system for the motor. The cooling system employs a forced ventilation structure, with a fan fixed to one end of the shaft and rotating synchronously with the rotor. Cooling air is circulated to the stator ends and winding surfaces through internal and external air ducts, achieving effective heat dissipation. The protection system includes temperature sensors, thermal relays, and pressure detectors, which monitor winding temperature, main circuit current, and internal housing pressure, respectively. When the detected signals exceed safety thresholds, the control module issues a shutdown command and cuts off the main power supply to ensure system safety.

[0049] With the above structure and wiring method, the motor maintains good electromagnetic performance during dual-speed operation. When one winding is energized, the other winding does not generate induced circulating current, resulting in reduced stator temperature rise and significantly improved motor efficiency. Test results show that this scheme enables the motor to operate stably under high load conditions, with high starting torque, reduced temperature rise by approximately 15% to 20%, significantly reduced operating noise, and a simple and easy-to-implement structure, making it suitable for the design and manufacture of high-power positive-pressure housing type dual-winding dual-speed asynchronous motors.

[0050] Implementation Method 3, in conjunction with Appendix Figure 1-5 This embodiment describes the technical solution provided above in further detail through specific examples. Specifically: Incorrect wiring of a positive-pressure housing type dual-winding dual-speed motor will result in excessive motor current, reduced motor efficiency, and increased temperature rise. In severe cases, it may even cause the motor to overheat and burn out. The motor surface temperature will also be excessively high, exceeding the corresponding limit temperature of the positive-pressure motor, increasing safety risks. This embodiment of a wiring method for a dual-winding dual-speed motor and a positive-pressure housing type three-phase asynchronous motor provides a method for eliminating circulating current in the stator branch of the positive-pressure housing type dual-speed motor. During the electromagnetic design of the dual-winding dual-speed motor, circulating current analysis is performed under different pole numbers to reduce the harmonic magnetomotive force generated by the working winding in the air gap. Weakening this magnetomotive force can also weaken the potential generated by cutting the other winding.

[0051] Taking the YDZYK 560kW / 315kW 6kV 50Hz motor as an example for analysis: Motor winding data: Stator slot count Z1 = 72 slots; 4P: Double layer, pole pitch is 18, slot pitch angle is 10 º, number of slots per pole per phase is 6; 6P: Double-layer, pole pitch is 12, slot pitch angle is 15°, and the number of slots per pole per phase is 4; The phase sequence and current direction of the upper or lower part of each slot 4P winding are as follows (ABC is the forward current, XYZ is the reverse current).

[0052]

[0053]

[0054] When the 6P circuit is running, the wiring status of the 4P winding is as follows: When the 6P winding is energized, the fundamental magnetomotive force in the air gap magnetic field rotates relative to the stator at a speed of 6P and cuts the stator winding, generating an induced electromotive force in the stator winding. At this time, in the 4P winding, the phase difference between the adjacent pole phase resistance is: 18×10º×6 / 4=270º. The induced electromotive forces of the four in-phase electrode groups are as follows: Assumption: E 1-6 =E<0 º; Then: E 24-19 = -E<270° = E<90° E 37-42 = E<0 º E 60-55 = -E<270° = E<90°; The circulating current in the closed loop of each phase winding of a 4P circuit is analyzed using a 2-way Y-connection as an example.

[0055] The first connection method is as follows: Figure 1 : ∑E= E 1-6 +E 37-42 -E 24-19 -E 60-55 =E<0 º+ E<0 º- E<90 º- E<90 º≠0; The second connection method is as follows: Figure 2 : ∑E= E 1-6 +E 24-19 -E 37-42 -E 60-55 = E<0 º+ E<90 º- E<0 º- E<90 º=0; As can be seen from the two connection methods above, the induced potentials in the first connection method cannot cancel each other out and can form a circulating current. In the second connection method, the induced potentials in each branch cancel each other out, and the combined potential is 0, so a circulating current cannot be formed.

[0056] When the 4P winding is running, the wiring status of the 6P winding is as follows: When the 4P winding is energized, the fundamental magnetomotive force in the air gap magnetic field rotates relative to the stator at a speed of 4P and cuts the stator winding, generating an induced electromotive force in the stator winding. At this time, in the 6P winding, the phase difference between the adjacent pole phase resistance is: 12×15 º×4 / 6=120 º. The induced electromotive forces of the six in-phase electrode groups are as follows: Assumption: E 1-4 =E<0 º; Then: E 16-13 = -E<120 º E 25-28 = E<240° = E<-120° E 40-37 = -E<0 º E 52-49 = E<120 º E61-64 = -E<240º=-E<-120º; The first connection method is as follows: Figure 3 : ∑E= E 1-4 + E 16-13+ +E 25-28-- E 40-37-- E 52-49-- E 61-64 = E<0 º-E<120 º+E<-120 º+ E<0 º- E<120 º+ E<-120 º =2 E<0 º-2 E<120 º+2 E<-120 º≠0; The second connection method is as follows: Figure 4 : ∑E= E 1-4 +E 25-28 +E 52-49 - E 16-13 - E 40-37 - E 61-64 =E<0 º+E<-120 º+E<120 º+ E<120 º+ E<0 º+ E<-120 º =2 E<0 º +2 E<-120 º +2 E<120 º =0; The third connection method is as follows: Figure 5 : ∑E= E 1-4 + E 52-49 +E 16-13 -- E 25-28-- E 40-37-- E 61-64 = E<0 º+E<120 º-E<120 º -E<-120 º+ E<0 º+ E<-120 º =2 E<0 º≠0; As can be seen from the above three connection methods, the induced electromotive forces in the first and third connection methods cannot cancel each other out and can form a circulating current. In the second connection method, the induced electromotive forces in each branch cancel each other out, and the combined electromotive force is 0, so a circulating current cannot be formed.

[0057] As can be seen from the above analysis, only one coil of the stator winding of the dual-speed motor is energized. The energized coil establishes a three-phase alternating magnetic field, and the other winding is equivalent to a closed loop under the magnetic field, resulting in an induced electromotive force. The generated magnetic field affects the energized winding, causing the motor to malfunction. Therefore, the induced electromotive force in the unenergized winding circuit is zero.

[0058] The above description of several specific embodiments further details the technical solution provided by the present invention in order to highlight the advantages and benefits of the technical solution provided by the present invention. However, the above-described specific embodiments are not intended to limit the present invention. Any reasonable modifications and improvements to the present invention, combinations of embodiments, and equivalent substitutions based on the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of connecting a dual-winding dual-speed motor, characterized by, The method comprises the following steps: Two sets of independent three-phase symmetrical windings are arranged in the motor stator, and correspond to different pole pair numbers in operation; According to the corresponding relationship between the motor stator slot number and the pole pair number, the pole pitch and the slot pitch angle of each winding are determined, and the two sets of windings are arranged in the stator slots in a mutually staggered embedding manner, so that the two sets of windings are separated in space and electrically isolated from each other; In the electromagnetic design stage, the circulating current formation conditions under different pole numbers are analyzed, and the phase difference distribution of the induced potential of each pole phase group in the non-working winding when one set of winding is energized is determined; According to the phase difference distribution result, the connection mode of the winding is determined, so that the induced potential directions of adjacent pole phase groups in the non-working winding are opposite and offset each other; In the connection design of the parallel windings, the number of parallel branches and the connection sequence of each phase winding are determined, so that the induced potential directions in each parallel branch are consistent, and the potentials between the branches offset each other; Through the connection terminal box, the windings of different pole pairs are independently connected, and the control system selectively connects the corresponding windings, so that only one set of winding is in the energized state during the switching process.

2. A dual-winding dual-speed motor connection method according to claim 1, characterized in that, The two sets of three-phase symmetrical windings adopt Y-shaped connection mode, each phase winding is composed of a plurality of coils in series, and the electrical angle between the three-phase windings is 120 degrees.

3. A dual-winding dual-speed motor connection method according to claim 1, characterized in that, In the two sets of three-phase symmetrical windings, the upper layer coils of one set of winding are located between the lower layer coils of the other set of winding.

4. A dual-winding dual-speed motor connection method according to claim 1, characterized in that, The determination of the winding connection mode comprises establishing an induced potential vector distribution model, and determining the connection sequence based on the phase difference of the potential of each pole phase group, so that the synthesized potential of each phase is zero.

5. A dual-winding dual-speed motor connection method according to claim 1, characterized in that, In the parallel winding design, when two or more parallel paths are used, the connection point positions of each parallel branch are arranged staggered, so that the induced potential directions in adjacent branches are opposite.

6. A dual-winding dual-speed motor connection method according to claim 1, characterized in that, The selection of the coil span is based on the analysis result of the air gap magnetic flux density distribution, and the harmonic magnetic potential generated by the working winding is weakened by adjusting the span.

7. A three-phase asynchronous motor of the positive- pressure-enclosure type, characterized in that The method of claim 1 realizes the connection, including a motor housing, a stator, a rotor, a connection terminal box and a control system; The motor housing is a positive pressure explosion-proof structure, and the inside of the housing maintains a micro-positive pressure higher than the outside environment; The stator is provided with two sets of independent three-phase symmetrical windings, which correspond to different pole pair numbers in operation and are used to realize double-speed operation; The two sets of independent three-phase symmetrical windings are arranged in the stator slots in a mutually staggered embedding manner and are electrically isolated from each other; In the three-phase symmetrical winding, the induced potential directions of each pole phase group in the non-working winding are opposite and offset each other; The connection terminal box is provided with two groups of independent three-phase input terminals and star point terminals corresponding to the two sets of three-phase symmetrical windings, and the control system is used to selectively connect different windings to realize double-speed switching; The control system is used to ensure that the two sets of windings are not electrified at the same time during the switching process; The rotor generates a rotating magnetic field through electromagnetic coupling with the stator magnetic field; The motor is provided with a cooling system for reducing the temperature rise of the stator winding.

8. Computer storage medium for storing a computer program, characterized in that When the computer program is read by the computer, the computer executes the method of claim 1.

9. A computer comprising a processor and a storage medium, characterized in that When the processor reads the computer program stored in the storage medium, the computer executes the method of claim 1.

10. Computer program product as computer program, characterized in that When the computer program is executed, the method of claim 1 is implemented.

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