A high-power tooth-slot-free permanent-magnet brushless direct-current motor with mortise and tenon joint winding connection

Abstract

The application relates to the field of motor structure and control technology, and discloses a high-power tooth-slot-free permanent-magnet brushless direct-current motor with tenon-and-slot clamping winding connection, which comprises a shell, a junction box, a stator core and a rotor, the stator winding is connected with a first connecting rod, the shell is fixedly provided with a second connecting rod, the two are clamped through a fixed hole and a sliding groove, the junction box is integrated with a clearance identification module, a hierarchical pre-tightening module, a state monitoring module and a self-adaptive adjusting module, the clearance identification module is used for injecting a double-frequency alternating current to convert an initial physical clearance; the hierarchical pre-tightening module actively closes the tenon-and-slot gap by using thermal expansion or electromagnetic bias according to a torque instruction derivative; and the state monitoring module extracts an admittance phase angle to calculate a tenon-and-slot micro-strain index. The application actively eliminates assembly clearance to avoid mechanical impact, realizes online monitoring and resonance suppression of structural stress, and improves the mechanical stability and safety of the tenon-and-slot clamping structure.

Description

Technical Field

[0001] This invention relates to the field of motor structure and control technology, specifically to a high-power slotless permanent magnet brushless DC motor with tenon-and-groove snap-fit ​​winding connection. Background Technology

[0002] The stator assembly of high-power cogging permanent magnet brushless DC motors often uses tenon and slot joints to simplify assembly. Due to limitations in machining precision, an initial physical clearance inevitably exists between the mating surfaces. Under frequent start-stop or high dynamic load conditions, this clearance can cause relative displacement and hard impacts of the connected components, exacerbating wear and fatigue damage. Existing passive treatment methods such as improving machining precision or overall potting not only increase manufacturing costs, but also cause the fixing materials to age and fail under thermal stress and vibration, making it impossible to actively compensate for mechanical clearance.

[0003] In addition, the electromagnetic excitation force generated when the motor is running at high power, combined with the influence of mechanical clearance, will cause resonance and micro-strain in the stator structure. Existing control systems have difficulty in attaching physical strain gauges on a large scale in the small space with strong interference inside the motor, which makes it impossible to obtain the real-time stress state of the stator clamping structure. Due to the lack of sensorless online monitoring methods and active suppression mechanisms for physical excitation forces, the structural safety of existing motors under high load conditions is difficult to guarantee. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a high-power slotless permanent magnet brushless DC motor with a tenon-and-groove snap-fit ​​winding connection. This solves the problems of existing motor tenon-and-groove snap-fit ​​structures causing mechanical impacts under dynamic loads due to assembly clearance, and the lack of sensorless online monitoring and active suppression of internal mechanical stress and resonance.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a high-power slotless permanent magnet brushless DC motor with a tenon-and-groove snap-fit ​​winding connection, comprising a base, an outer shell fixedly connected to the outer side of the base, heat sinks provided on the outer side of the outer shell, a junction box fixedly connected to the outer side of the outer shell, a rotating shaft rotatably connected to the inner side of the outer shell, a squirrel-cage rotor fixedly connected to the outer side of the rotating shaft, a stator core fixedly connected to the inner side of the outer shell, a stator winding provided on the outer side of the squirrel-cage rotor, a second connecting rod fixedly connected to the inner side of the outer shell, a first connecting rod fixedly connected to one end of the stator winding, fixing holes provided inside both the second and first connecting rods, sliding grooves provided on the outer sides of both the second and first connecting rods, fixing posts fixedly connected to the outer sides of both the first and second connecting rods, the fixing posts slidably connected to the outer side of the fixing holes, and pins slidably connected to the outer side of the sliding grooves; A clearance identification module is fixedly connected to the top of the junction box. The clearance identification module is used to inject dual-frequency micro-amplitude alternating current. A graded pre-tightening module is fixedly connected to the top of the junction box. The graded pre-tightening module is used to calculate the time derivative of the externally input torque command in real time. A state monitoring module is fixedly connected to the outside of the junction box. The state monitoring module is used to extract the admittance phase angle and calculate the tenon groove micro-strain index. An adaptive adjustment module is fixedly connected to the outside of the junction box. The adaptive adjustment module is used to counteract the physical excitation force and forcibly reduce the steady-state amplitude limit of the quadrature axis current.

[0006] Preferably, the clearance identification module integrates a signal generation unit. The test current signal injected by the signal generation unit into the quadrature axis current command channel is a linear superposition of a sine wave with a first high-frequency carrier angular frequency and a sine wave with a second high-frequency carrier angular frequency. The amplitude of the alternating test current signal is controlled below a set threshold corresponding to the static friction torque of the motor to isolate the coupling superposition of back electromotive force.

[0007] Preferably, the gap identification module integrates a differential calculation unit and a gap quantization unit. The differential calculation unit extracts the total phase delay time and subtracts the product of the first high-frequency carrier angle frequency and the total phase delay time from the product of the second high-frequency carrier angle frequency and the corresponding total phase delay time. The calculated difference is divided by the difference between the second high-frequency carrier angle frequency and the first high-frequency carrier angle frequency to construct a differential equation to cancel the electrical delay time term and obtain the pure mechanical delay time term. The clearance quantization unit multiplies the pure mechanical delay time by the offline fitted clearance stiffness conversion coefficient to convert it into the initial physical clearance in the spatial dimension.

[0008] Preferably, the graded pre-tightening module integrates an instruction derivative calculator, a state comparator, a thermal expansion control branch, and an electromagnetic bias control branch. The state comparator compares the time derivative with a preset step rate determination threshold. When the time derivative is lower than the step rate determination threshold, the thermal expansion control branch is activated to respond to a state of slow acceleration or low dynamic response. When the time derivative is higher than or equal to the step rate determination threshold, the electromagnetic bias control branch is activated to respond to a high dynamic operating condition.

[0009] Preferably, the thermal expansion control branch continuously injects controlled reactive heating current into the direct-axis current channel according to the initial physical clearance, and uses the Joule heat generated in the stator winding to induce the thermal expansion displacement of the first connecting rod. The extension of the thermal expansion displacement of the first connecting rod gradually closes in space and fills the existing initial physical clearance, thereby achieving flexible fit. The electromagnetic bias control branch injects transient pressure current into the direct axis, which excites a unidirectional transient radial electromagnetic attraction force equal to the clearance stiffness resistance, forcibly pressing the first connecting rod at the end of the stator winding onto the bearing surface of the second connecting rod to form a rigid contact state.

[0010] Preferably, the status monitoring module integrates a high-frequency carrier modulator and a heterodyne demodulator. The high-frequency carrier modulator superimposes in real time the orthogonal high-frequency voltage carrier with constant frequency and amplitude and maintaining an orthogonal differential relationship in spatial phase onto the basic magnetic field orientation control voltage command. The heterodyne demodulator uses the orthogonal phase-locked loop demodulation algorithm to heterodyne the extracted actual high-frequency response current and the local reference carrier, and attenuates the second harmonic component through a low-pass filter. It then calculates the imaginary and real components of the extracted high-frequency current through arctangent calculation logic to obtain the direct-axis high-frequency admittance phase angle and the quadrature-axis high-frequency admittance phase angle.

[0011] Preferably, the state monitoring module also integrates a feature reconstruction unit. The feature reconstruction unit subtracts the phase angle of the direct-axis high-frequency admittance from the phase angle of the quadrature-axis high-frequency admittance, deducts the absolute value of the static phase angle offset, and multiplies it by the sensitivity amplification factor calibrated offline to reconstruct the tenon groove micro-strain index, so as to characterize the real-time stress state and geometric eccentricity of the tenon groove clamping structure during operation.

[0012] Preferably, the adaptive adjustment module integrates a harmonic suppression unit. The harmonic suppression unit has a built-in dynamic mapping table of the stator structure's natural frequency with respect to the tenon groove micro-strain index. When it detects that the electromagnetic excitation frequency extracted by the fast Fourier transform has entered the resonance critical bandwidth of the corrected stator structure's real-time natural frequency, it superimposes an anti-phase harmonic current compensation amount with the same frequency and amplitude but a phase difference of 180 degrees onto the quadrature axis current command. This eliminates the electromagnetic torque fluctuations caused by the stator current harmonics, thereby actively canceling the mechanical excitation force that causes resonance at the physical level.

[0013] Preferably, the adaptive adjustment module also integrates a state evaluation unit, a neural network prediction unit, and an instruction correction unit. The neural network prediction unit is equipped with a three-layer feedforward neural network model. The three-layer feedforward neural network model maps the current tenon groove micro-strain index, rotor mechanical speed and direct axis current through the minimum maximum normalization algorithm as a three-dimensional feature input vector, and propagates forward to calculate and output the dynamic torque derating coefficient. The instruction correction unit performs an algebraic multiplication operation on the dynamic torque derating coefficient and the quadrature axis torque current instruction, and linearly superimposes the anti-phase harmonic current compensation amount to generate the reconstructed final quadrature axis torque current instruction, which is then sent to the current closed-loop regulator.

[0014] Preferably, when the state assessment unit detects that the micro-strain index of the tenon groove falls below the recovery dead zone set by the elastic deformation warning threshold, the neural network prediction unit stops outputting actions, the command correction unit linearly restores the dynamic torque derating coefficient to its initial value according to the preset smoothing slope and releases the system torque limit, and the adaptive adjustment module continuously sends the reconstructed quadrature axis torque current command as the update benchmark to the current closed-loop regulator.

[0015] This invention provides a high-power slotless permanent magnet brushless DC motor with tongue and groove snap-fit ​​winding connection. It has the following advantages: 1. This invention addresses the assembly clearance issue between the first and second connecting rods in the tenon-and-slot snap-fit ​​winding connection structure of a motor. It quantifies the initial physical clearance using a clearance identification module and dynamically executes pre-tightening actions based on the time derivative of the torque command using a graded pre-tightening module. Under different operating conditions, the system utilizes reactive heating current to induce thermal expansion of the first connecting rod or uses transient pressure current to generate radial electromagnetic attraction, enabling flexible filling or rigid clamping of the first and second connecting rods at the stator winding ends. This mechanism actively closes the mechanical clearance within the tenon-and-slot snap-fit ​​structure, preventing relative sliding and mechanical impact on the tenon-and-slot mating surfaces under step loads, thus improving the stability of the winding mechanical connection.

[0016] 2. This invention superimposes an orthogonal high-frequency voltage carrier onto the motor's base control voltage using a condition monitoring module, extracts the high-frequency admittance phase angle using a heterodyne demodulation algorithm, and then calculates the micro-strain index of the tenon groove. This method eliminates the need for additional physical mechanical strain gauges inside the motor, directly utilizing the electrical response characteristics of the quadrature and direct axes to characterize the real-time stress state and geometric eccentricity of the stator clamping structure. This simplifies the motor's hardware assembly structure and facilitates sensorless online monitoring during continuous operation.

[0017] 3. This invention uses an adaptive adjustment module to dynamically correct the stator's natural frequency based on the extracted micro-strain index. When the electromagnetic excitation frequency enters the resonance bandwidth, an anti-phase harmonic current is injected into the current command to counteract the physical excitation force. At the same time, when the micro-strain index exceeds the warning threshold, a derating coefficient is output using a neural network model to forcibly reduce the quadrature axis torque current limit. This adjustment mechanism, which combines compensation and limiting, avoids resonance amplification and excessive deformation of the stator clamping structure, reducing the risk of fatigue damage to mechanical components. Attached Figure Description

[0018] Figure 1 This is a perspective view of the present invention; Figure 2 This is a schematic diagram of the stator core structure of the present invention; Figure 3This is a schematic diagram of the structure of the first connecting rod of the present invention; Figure 4 This is a schematic diagram of the system architecture of the present invention; Figure 5 This is a schematic diagram of the internal signal processing and logic control principle of the clearance identification module of the present invention; Figure 6 This is a timing diagram of the internal control structure and pre-tightening strategy of the graded pre-tightening module of the present invention; Figure 7 This is a diagram of the internal signal processing and feature extraction architecture of the status monitoring module of the present invention; Figure 8 This is a diagram showing the internal control architecture and dynamic derating data flow of the adaptive adjustment module of the present invention. Figure 9 Figure 1 shows a comparison of the transient torque response and stator vibration acceleration time series under step load conditions. Figure 2 shows a comparison of the torque response under step load conditions, and Figure 3 shows a comparison of the stator single-point vibration acceleration. Figure 10 A three-dimensional surface mapping of micro-strain exponent, mechanical speed and dynamic torque derating factor; Figure 11 A histogram comparing the high-frequency harmonic spectrum distribution of the stator quadrature-axis phase current.

[0019] The components include: 1. Base; 2. Housing; 3. Heat sink; 4. Junction box; 5. Squirrel cage rotor; 6. Stator winding; 7. Shaft; 8. Stator core; 9. First connecting rod; 10. Second connecting rod; 11. Fixing post; 12. Fixing hole; 13. Slide groove; 14. Pin; 101. Clearance identification module; 102. Graded pre-tightening module; 103. Status monitoring module; 104. Adaptive adjustment module. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] See attached document Figure 1-3This invention provides a high-power slotless permanent magnet brushless DC motor with a tenon-and-groove winding connection. The motor includes a base 1, which supports the motor body and fixes it to an external mounting plane, providing structural support. A housing 2 is fixedly connected to the outside of the base 1. Heat sinks 3 are provided on the outside of the housing 2 to increase the surface area of ​​the housing 2, conducting and dissipating internally generated heat. A junction box 4 is fixedly connected to the outside of the housing 2. A rotating shaft 7 is rotatably connected to the inside of the housing 2. A squirrel-cage rotor 5 is fixedly connected to the outside of the rotating shaft 7. A stator core 8 is fixedly connected to the inside of the housing 2, providing an internal closed magnetic circuit and providing slot support and a fixing reference for the stator windings 6. A stator winding 6 is provided on the outer side of the sub-5. A second connecting rod 10 is fixedly connected to the inner side of the outer shell 2. A first connecting rod 9 is fixedly connected to one end of the stator winding 6. Fixing holes 12 are provided inside both the second connecting rod 10 and the first connecting rod 9. The fixing holes 12 are used to accommodate the fixing post 11 and the pin 14 to establish the spatial positioning reference of the assembly. Sliding grooves 13 are provided on the outer sides of both the second connecting rod 10 and the first connecting rod 9. Sliding grooves 13 are used to guide the sliding trajectory of the pin 14 and limit the radial movement range of the connecting assembly. Fixing posts 11 are fixedly connected to the outer sides of both the first connecting rod 9 and the second connecting rod 10. The outer side of the fixing post 11 is slidably connected to the inside of the fixing hole 12. The outer side of the sliding groove 13 is slidably connected to the pin 14.

[0022] Specifically, the base 1 supports the motor body and is fixed on the external mounting plane. The outer shell 2 encloses the internal structure of the motor. The heat sink 3 dissipates the heat conducted inside the outer shell 2. The junction box 4 houses the external electrical terminals. The rotating shaft 7 outputs the mechanical power generated by the operation of the squirrel-cage rotor 5. The squirrel-cage rotor 5 generates electromagnetic torque in the magnetic field excited by the stator winding 6. The stator core 8 provides an internal closed magnetic circuit and slot fixing reference for the stator winding 6. The end of the stator winding 6 is equipped with a first connecting rod 9. The inside of the outer shell 2 is equipped with a second connecting rod 10. The fixing holes 12 on the first connecting rod 9 and the second connecting rod 10 accommodate the fixing post 11 to establish a spatial positioning reference. The sliding grooves 13 on the first connecting rod 9 and the second connecting rod 10 guide the sliding trajectory of the pin 14. The pin 14 passes through the fixing hole 12 along the sliding groove 13 to lock the relative position of the first connecting rod 9 and the second connecting rod 10.

[0023] See attached document Figure 4 , Figure 4 This is a schematic diagram of a system architecture according to an embodiment of the present invention. The present invention provides a high-power slotless permanent magnet brushless DC motor with tenon-and-groove snap-fit ​​winding connection, which may include: a clearance identification module 101, a graded preload module 102, a status monitoring module 103, and an adaptive adjustment module 104.

[0024] The clearance identification module 101 is used to inject dual-frequency micro-amplitude alternating current into the stator winding 6 during the standby phase when the motor speed is zero. By acquiring the phase current response signal and performing differential calculation, the pure mechanical delay time between the first connecting rod 9 and the second connecting rod 10 is calculated, thereby quantifying the initial physical clearance of the tenon and slot structure. The output end of the clearance identification module 101 is connected to the graded pre-tightening module 102, and the calculated clearance parameters are used as the initial boundary conditions for subsequent pre-tightening logic.

[0025] The graded preload module 102 is used to calculate the time derivative of the externally input torque command in real time. According to the magnitude of the load step rate, the graded preload module 102 selectively injects reactive heating current or transient pressure current into the direct shaft. When the command change rate is lower than the preset threshold, the graded preload module 102 controls the direct shaft current to trigger the first connecting rod 9 to generate thermal expansion displacement through the Joule heat generated by the stator winding 6 to fill the initial physical clearance. When the command change rate is higher than the preset threshold, the graded preload module 102 controls the direct shaft to generate transient electromagnetic attraction force to press the first connecting rod 9 against the bearing surface of the second connecting rod 10. After completing the preload action, the graded preload module 102 sends a command to the inverter drive module of the motor to release the quadrature shaft torque current.

[0026] The condition monitoring module 103 is used to superimpose an orthogonal high-frequency voltage carrier onto the basic magnetic field orientation control voltage command during motor operation, and extract the admittance phase angle characteristics from the high-frequency response of the phase current using an orthogonal phase-locked demodulation algorithm. The condition monitoring module 103 calculates the tenon groove micro-strain index by comparing the admittance phase angle deviation between the direct axis and the quadrature axis, which is used to characterize the real-time stress state and geometric offset of the tenon groove clamping structure during operation. The output of the condition monitoring module 103 is connected to the adaptive adjustment module 104.

[0027] The adaptive adjustment module 104 is used to dynamically correct the natural frequency mapping value of the stator structure based on the tenon groove micro-strain index output by the state monitoring module 103. The adaptive adjustment module 104 monitors the proximity between the motor excitation frequency and the natural frequency of the stator structure in real time, and injects anti-phase harmonic current compensation into the quadrature axis current command within the resonance critical bandwidth. The physical excitation force is offset by electromagnetic pulsation. At the same time, when the tenon groove micro-strain index exceeds the set threshold, the adaptive adjustment module 104 sets the threshold to the elastic deformation warning threshold based on the yield limit of the materials of the first connecting rod 9 and the second connecting rod 10 offline calibration. The threshold is usually taken as the micro-strain value corresponding to 70% to 85% of the material's ultimate yield stress. Within this range, derating is triggered, which can strictly avoid irreversible mechanical damage or fatigue fracture of the connecting components while ensuring high power output of the motor, and forcibly reduce the steady-state amplitude limit of the quadrature axis current.

[0028] See attached document Figure 5 , Figure 5This is a schematic diagram of the internal signal processing and logic control of the clearance identification module according to an embodiment of the present invention. In this embodiment, the clearance identification module 101 integrates a signal generation unit, a differential calculation unit, and a clearance quantization unit. In the static stage when the motor does not respond to external load commands, the clearance identification module 101 separates the inverter dead zone and related electromagnetic parameters of parasitic capacitance based on the time delay characteristics in the electrical response signal, and outputs the initial physical clearance of the mechanical structure through calculation.

[0029] After the system starts, the motor controller continuously monitors the speed feedback signal of the rotor position sensor. When the motor is detected to be in a zero-speed standby state, the clearance identification module 101 activates the internal signal generation unit. The signal generation unit injects a micro-amplitude alternating test current signal containing two different high-frequency carrier angular frequencies into the quadrature-axis current command channel of the motor controller. As a preferred method, the amplitude of the test current signal is limited and controlled below the motor starting friction torque threshold based on the starting friction torque measured offline by the motor. In this embodiment, it is set to generate an equivalent electromagnetic torque less than 70% to 85% of the starting static friction torque, and the current amplitude is limited to 5% to 10% of the rated current of the motor. This limits the macroscopic mechanical rotation of the rotor during the test and isolates the coupling superposition of the back electromotive force on the test current response. Specifically, the injected test signal is a linear superposition of a sine wave with a first high-frequency carrier angular frequency and a sine wave with a second high-frequency carrier angular frequency, and both have the same limited current amplitude.

[0030] The phase current sensor acquires the three-phase current response signal of the stator winding 6 and obtains the actual quadrature axis response current through coordinate transformation. The first connecting rod 9 and the second connecting rod 10 at the end of the stator winding 6 are engaged by a tenon and slot structure. The clearance generated by long-term vibration on the mechanical mating surface will form a nonlinear physical collision dead zone during the transmission of high-frequency micro vibration. This collision dead zone is manifested as an additional time delay in the phase response of the current control loop. The differential calculation unit in the clearance identification module 101 receives the quadrature axis response current and extracts the total phase delay time corresponding to the first high-frequency carrier angular frequency and the second high-frequency carrier angular frequency respectively. The total phase delay time includes the electrical delay time caused by the parasitic parameters of the electrical circuit and inversely proportional to the excitation frequency, and the pure mechanical delay time caused by the initial physical clearance and exhibiting a constant behavior.

[0031] The differential calculation unit subtracts the product of the first high-frequency carrier angular frequency and its corresponding total phase delay time from the product of the second high-frequency carrier angular frequency and its corresponding total phase delay time, and divides this calculated difference by the difference between the second and first high-frequency carrier angular frequencies. This constructs a differential equation to cancel out the electrical delay time term, which is inversely proportional to the excitation frequency. The expression for the differential equation is: ; In the formula, It is the pure mechanical delay time, which is the time lag caused entirely by the nonlinear collision dead zone generated by mechanical gaps. It is a parasitic parameter independent of electrical components. This refers to the total phase delay time corresponding to the extracted first high-frequency carrier angular frequency; This refers to the total phase delay time corresponding to the extracted second high-frequency carrier angular frequency; The first high-frequency carrier angular frequency is the frequency value, which is distributed within the high-frequency response range of the motor current control loop bandwidth. In this embodiment, the frequency value range is 1000Hz to 1500Hz. The second high-frequency carrier angular frequency is distributed within the high-frequency response range of the motor current control loop bandwidth. In this embodiment, the frequency range is 2000Hz to 2500Hz, and it is necessary to ensure that there is a frequency difference of at least 500Hz with the first high-frequency carrier to ensure the sensitivity of differential calculation.

[0032] The clearance quantization unit within the clearance identification module 101 receives the pure mechanical delay time output by the differential calculation unit. This clearance quantization unit pre-stores a clearance stiffness mapping model established through offline calibration experiments. Substituting this mapping model, the clearance quantization unit converts the pure mechanical delay time in the time dimension into the initial physical clearance in the spatial dimension. The clearance conversion formula is as follows: ; In the formula, The initial physical clearance obtained from the calculation, This is the clearance stiffness conversion factor obtained by offline fitting of the elastic modulus of the structural component material and the assembly dimensions; The time is purely mechanical delay. The gap identification module 101 sends the calculated initial physical gap to the input of the graded preload module 102 via the internal data bus as the basic boundary parameter for the subsequent mechanical preload strategy execution. The conventional coordinate transformation algorithm for phase current sampling can be implemented based on existing digital signal processing technology.

[0033] See attached document Figure 6 , Figure 6This is a timing diagram of the internal control structure and pre-tightening strategy of a graded pre-tightening module according to an embodiment of the present invention. In this embodiment, the graded pre-tightening module 102 integrates an instruction derivative calculator, a state comparator, a thermal expansion control branch, an electromagnetic bias control branch, and a pre-tightening interlock release unit. After receiving an externally input torque command, the instruction derivative calculator performs differential calculation in real time to extract the time derivative of the torque command. The time derivative physically represents the load step rate under dynamic conditions. The state comparator obtains the time derivative and compares it with a preset step rate judgment threshold in the system. The step rate judgment threshold is set in the range of 10 Nm / ms to 50 Nm / ms. The system performs numerical comparison and outputs the corresponding control branch trigger command. The step rate judgment threshold is calculated offline based on the product of the rotor inertia of the motor and the maximum allowable acceleration of the system. The system establishes an objective judgment boundary to distinguish between gradually changing conditions and abruptly changing conditions and selects the pre-tightening path accordingly.

[0034] The system employs differentiated pre-tightening strategies based on internal logic scheduling to address different comparison results. When the time derivative of the torque command determined by the state comparator is lower than the preset step rate threshold, the system activates the thermal expansion control branch. At this time, the motor is in a state of slow acceleration or low dynamic response demand. The thermal expansion control branch extracts the initial physical clearance issued by the clearance identification module 101 and calculates the required pre-tightening temperature rise based on the linear expansion coefficient of the material of the first connecting rod 9. Subsequently, the thermal expansion control branch continuously injects controlled reactive heating current into the direct-axis current channel of the motor controller, i.e., without generating quadrature-axis electromagnetic torque, specifically for the main stator winding 6. The direct-axis current component that generates heat is set to an amplitude range of 20% to 40% of the motor's rated current in the stator winding 6, generating Joule heat in the stator winding 6. Simultaneously, within the pre-tightening time window of the gradually changing load heating, the system will forcibly reduce the output slope of the quadrature-axis torque current command and clamp it to a low-limit state matching the clearance closing rate to avoid the impact caused by sudden closure of the mechanical dead zone. The Joule heat is conducted between the motor stator frame and the structural components, causing the thermal expansion displacement of the first connecting rod 9. The extension of the thermal expansion displacement of the first connecting rod 9 gradually closes in space and fills the existing initial physical clearance, thereby achieving a flexible fit.

[0035] As a preferred approach, a first-order discrete temperature rise observation and thermal expansion mapping model is established within the thermal expansion control branch. The algebraic mapping relationship between the required reactive heating current amplitude and the physical clearance is as follows: ; In the formula, Reactive heating current injected into the direct axis; The equivalent heat capacity coefficient of stator winding 6 and connecting rod assembly is obtained by multiplying the specific heat capacity and volume of the material. The initial physical clearance obtained from the calculation; This is the phase resistance of stator winding 6; The coefficient of linear expansion of the material of the first connecting rod 9; This is the thermal expansion length of the first connecting rod 9; The pre-tightening time window for the gradually changing load heating is set for the system, with a preset value range of 1000ms to 5000ms. During this heating process, the system synchronously introduces the feedback value of the winding temperature sensor and cuts off the reactive heating current injection before the insulation material reaches its temperature resistance limit to limit the risk of thermal breakdown of the system.

[0036] When faced with a highly dynamic operating condition, i.e. when the time derivative of the torque command determined by the state comparator is higher than or equal to the preset step rate determination threshold, the system activates the electromagnetic bias control branch. In the initial stage of control, the system forcibly limits and reduces the rising slope of the amplitude of the quadrature axis torque current command. At the same time, the electromagnetic bias control branch injects transient pressure current into the direct axis. The transient pressure current excites a high-intensity transient radial electromagnetic attraction in the large gap magnetic circuit of the slotless permanent magnet motor. The unidirectional radial electromagnetic force forcibly presses the first connecting rod 9 at the end of the stator winding 6 against the bearing surface of the second connecting rod. The system relies on the electromagnetic bias force to close the collision dead zone of the mechanical component mating surface in the tangential dimension and form a rigid contact state.

[0037] The magnitude of the transient radial electromagnetic attraction force matches the equivalent clearance stiffness resistance corresponding to the initial physical clearance. The formula for calculating the direct-axis transient pressure current in the electromagnetic bias control branch is as follows: ; In the formula, Transient pressure current injected along the direct axis; The equivalent stationary air gap length between the stator and rotor of the motor; This is the clearance stiffness conversion factor calibrated offline, and its value range is limited to the normal elastic deformation range based on assembly tolerances. The typical calibration value range is 5 × 10. 4 N / m to 2×10 5 N / m; The initial physical clearance obtained from the calculation; This represents the number of pole pairs of the motor. This is the effective core length of the motor; Permeability of free space; The equivalent number of series turns for a single-phase winding of stator winding 6; the pulse duration is set according to the step response time of the current control loop.

[0038] During the execution cycle of the aforementioned pre-tightening action, the pre-tightening interlock release unit in the graded pre-tightening module 102 continuously monitors the operating status of the dual branches. When the pre-tightening interlock release unit detects that the expansion corresponding to the heat generated by the stator winding 6 covers the initial physical clearance or detects that the transient electromagnetic clamping action time window has ended, it generates an internal unlocking signal. Based on the internal unlocking signal, the pre-tightening interlock release unit sends a release command to the inverter drive module to forcibly reduce the amplitude of the quadrature axis torque current. The motor controller then releases the initial rising slope limit set on the quadrature axis current and restores the normal torque command tracking logic. The torque command differential algorithm and the basic current limiting logic can be implemented using existing automatic control technology.

[0039] See attached document Figure 7 , Figure 7 This is an internal signal processing and feature extraction architecture diagram of a state monitoring module according to an embodiment of the present invention. In this embodiment, the state monitoring module 103 integrates a high-frequency carrier modulator, a heterodyne demodulator, and a feature reconstruction unit. When the motor is in continuous operation, the state monitoring module 103 synchronously starts online monitoring logic to extract structural distortion feature parameters.

[0040] In this embodiment, the brushless DC motor adopts a sinusoidal drive strategy to improve smoothness. The high-frequency carrier modulator receives the basic magnetic field orientation control voltage command output from the motor's basic magnetic field orientation control loop and superimposes an orthogonal high-frequency voltage carrier with constant frequency and amplitude on the basic magnetic field orientation control voltage command channel in real time. Its injection frequency is preset to be more than ten times the highest frequency of the fundamental wave operation and less than one-third of the inverter switching frequency, thereby establishing an independent monitoring frequency band without overlap in the frequency domain.

[0041] As a preferred approach, the synthesized voltage command output by the high-frequency carrier modulator includes a basic magnetic field orientation control voltage command and an additional high-frequency carrier component. When constructing the carrier, the system ensures that the high-frequency voltage carriers superimposed on the direct and quadrature axes maintain an orthogonal differential relationship in spatial phase and maintain consistent peak amplitudes. The high-frequency voltage carrier injection expression executed internally by the state monitoring module 103 is: ; In the formula, It is a high-frequency voltage carrier command superimposed on the direct axis; The amplitude of the set high-frequency carrier voltage is dynamically limited based on the real-time sampling value of the DC bus voltage sensor. The upper limit of the dynamic limit is strictly limited to 5% to 10% of the current DC bus voltage to avoid oversaturation of the motor's main magnetic circuit. The set high-frequency carrier angular frequency; It is a time variable.

[0042] ; In the formula, A high-frequency voltage carrier command with cross-axis superposition; The amplitude of the high-frequency carrier voltage is set, and its per-unit value is dynamically limited based on the real-time sampling value of the DC bus voltage sensor. The set high-frequency carrier angular frequency; The time variable is used; the control unit sends the synthesized three-phase voltage command to the inverter actuator and excites the corresponding high-frequency current response component in the stator winding 6.

[0043] The transient inductance parameters of the motor body along the direct and quadrature axes shift asymmetrically due to the microscopic stress deformation and local stress concentration of the stator tenon slot connection structure. The heterodyne demodulator receives the continuous phase current signal collected by the stator current sensor and extracts the actual high-frequency response current of the direct and quadrature axes through synchronous rotating coordinate transformation. The heterodyne demodulator uses an internally built-in quadrature phase-locked loop demodulation algorithm to heterodyne multiply this high-frequency response current with the local reference carrier and attenuates the second harmonic component through a low-pass filter. The system extracts the real and imaginary parts of the high-frequency current containing structural impedance information. Taking the direct axis as an example, the expression for calculating its high-frequency admittance phase angle is: ; In the formula, The phase angle of the direct-axis high-frequency admittance obtained by demodulation; This is the imaginary component of the direct-axis high-frequency response current output after heterodyne demodulation. The real component of the direct-axis high-frequency response current is obtained through heterodyne demodulation. The quadrature-axis high-frequency admittance phase angle is obtained using the same demodulation structure and arctangent calculation logic.

[0044] The feature reconstruction unit within the condition monitoring module 103 receives the direct-axis high-frequency admittance phase angle and the quadrature-axis high-frequency admittance phase angle continuously output by the heterodyne demodulator. The feature reconstruction unit compares the dynamic admittance phase angle deviations of the two axes and compensates for the static manufacturing offset of the structure to calculate and generate the tenon groove micro-strain index. The tenon groove micro-strain index is normalized to a pure numerical scalar between 0 and 100. The micro-strain index, as a dimensionless monitoring parameter, maps the real-time stress state and geometric eccentricity of the tenon groove clamping structure during operation. The tenon groove micro-strain index reconstruction formula, solidified within the feature reconstruction unit, is as follows: ; In the formula, To calculate the micro-strain index of the generated tenon groove; The sensitivity amplification factor is based on the offline calibration of the shear modulus of the system structural component material, and its value ranges from 10 to 50. The phase angle of the direct-axis high-frequency admittance obtained by demodulation; The phase angle of the cross-axis high-frequency admittance obtained by demodulation; The static phase angle offset is measured offline when the motor is unloaded and without mechanical stress. The state monitoring module 103 sends the micro-strain index obtained by real-time reconstruction to the adaptive adjustment module 104. The coordinate transformation algorithm for the phase current signal can be implemented by the conventional Clark transformation and Park transformation algorithms.

[0045] See attached document Figure 8 , Figure 8 This is an internal control architecture and dynamic derating data flow diagram of an adaptive adjustment module according to an embodiment of the present invention. In this embodiment, the adaptive adjustment module 104 integrates a state evaluation unit, a neural network prediction unit, a harmonic suppression unit, and an instruction correction unit.

[0046] The condition assessment unit continuously receives the tenon groove micro-strain index issued by the condition monitoring module 103 and compares it with the elastic deformation warning threshold solidified in the system in real time. The elastic deformation warning threshold is 70% to 85% of the yield limit stress of the corresponding mechanical material. This elastic deformation warning threshold is calculated offline based on the yield limit and fatigue life curve of the stator component mechanical material. When the condition assessment unit determines that the received tenon groove micro-strain index exceeds the elastic deformation warning threshold, it generates an over-limit trigger signal and wakes up the neural network prediction unit. During this comparison process, the system synchronously introduces hysteresis comparison logic to avoid high-frequency fluctuations of the strain index near the threshold critical point, which would cause frequent start-stop of the control system.

[0047] For the harmonic suppression unit, the unit has a built-in dynamic mapping table of the stator structure's natural frequency with respect to the tenon groove micro-strain index. During motor operation, the harmonic suppression unit extracts the current electromagnetic excitation frequency by performing a fast Fourier transform on the stator phase current, and queries the above mapping table based on the real-time input tenon groove micro-strain index to obtain the corrected real-time natural frequency of the stator structure. When the electromagnetic excitation frequency is detected to enter the resonance critical bandwidth of 95% to 105% of the real-time natural frequency, the harmonic suppression unit calculates the amplitude and phase corresponding to the stator current harmonic component at that excitation frequency, and superimposes an anti-phase harmonic current compensation amount with the same frequency, the same amplitude as the current harmonic component, and a phase difference of 180 degrees onto the quadrature axis current command. This generates a reverse electromagnetic torque pulsation, eliminates the electromagnetic torque fluctuation caused by the stator current harmonics, and thus actively cancels the mechanical excitation force that causes resonance at the physical level, thereby ensuring structural safety.

[0048] As a preferred approach, the neural network prediction unit is equipped with a pre-trained three-layer feedforward neural network model. The three-layer feedforward neural network model includes an input layer, a hidden layer, and an output layer. The system obtains the current tenon groove micro-strain index, rotor mechanical speed, and direct-axis current, and maps all values ​​to a dimensionless range of zero to one using a minimum-maximum normalization algorithm to form a three-dimensional feature input vector. The aforementioned feature input vector is fed into the input layer of the three-layer feedforward neural network model and then passed to the output layer after passing through the nonlinear activation function of the hidden layer. The output result of the output layer node is directly mapped to the dynamic torque derating coefficient at the physical level. This coefficient represents the maximum safe electromagnetic torque ratio boundary that the system can output under the current stress limit state.

[0049] The three-layer feedforward neural network model establishes a sample set by collecting multi-condition extreme test data from a motor dynamometer bench during the offline construction phase. The label data for training the three-layer feedforward neural network model comes from the optimal torque attenuation ratio calibrated by a strain gauge array under different high-load conditions. During the network training process, the backpropagation algorithm combined with an adaptive moment estimation optimizer is used to update the connection weights between the neurons at each layer. The model training uses the mean square error function, which calculates the deviation between the predicted output and the true label, as the loss function. The formula for calculating this loss function is as follows: ; In the formula, The calculated mean square error value; This represents the total number of samples in the training batch. This is the index variable for the training samples; Labels for the actual dynamic torque derating factor obtained for bench calibration; The predicted dynamic torque derating factor is calculated for the output of the current forward propagation of the neural network model.

[0050] The instruction correction unit receives the dynamic torque derating coefficient output in real time from the neural network prediction unit and the anti-phase harmonic current compensation amount output from the harmonic suppression unit. The system performs an algebraic multiplication operation on the dynamic torque derating coefficient and the amplitude of the forced reduction of quadrature-axis torque current command generated by the basic field-oriented control loop, and linearly superimposes the anti-phase harmonic current compensation amount on the product result. The system forcibly reduces the amplitude of the quadrature-axis torque current command according to the current stator structure distortion level. The attenuation of the current command causes the tangential electromagnetic thrust driving the rotor to decrease synchronously, thereby reducing the physical shear stress borne by the tenon and slot structure. At the same time, the superimposed anti-phase harmonic current compensation amount is used to accurately eliminate the electromagnetic pulsation source that generates physical excitation force. The current command reconstruction formula executed inside the instruction correction unit is: ; In the formula, The amplitude of the final forced reduction of the quadrature axis torque current command is reconstructed by the adaptive adjustment module 104. The dynamic torque derating factor output by the neural network is strictly limited to 0 to 1 based on physical boundaries. The magnitude of the forced reduction cross-axis torque current command generated by the basic field-oriented control; The anti-phase harmonic current compensation amount generated by the harmonic suppression unit has an injection frequency that is in the same frequency but out of phase with the electromagnetic excitation frequency of the motor. The dynamic amplitude limit range of the anti-phase harmonic current compensation amount is constrained to the amplitude of the forced reduction command of the quadrature shaft torque current. to Within this range, avoid causing system instability.

[0051] When the state assessment unit detects that the micro-strain index of the tenon groove has fallen below the recovery dead zone set by the elastic deformation warning threshold, the neural network prediction unit stops outputting. The command correction unit linearly restores the dynamic torque derating coefficient to its initial value according to the preset smooth slope and removes the system torque limit. The adaptive adjustment module 104 continuously sends the amplitude of the reconstructed forced reduction of quadrature axis torque current command as the update reference to the current closed-loop regulator. The proportional-integral closed-loop regulation algorithm of the stator current and the space vector pulse width modulation technology can be implemented by conventional PI control and SVPWM algorithm.

[0052] Application Examples To further aid in understanding the technical solution of the present invention and to verify its practical application effect, the following is an application embodiment of a high-power slotless permanent magnet brushless DC motor with tenon-groove snap-fit ​​winding connection.

[0053] Taking a high-power slotless permanent magnet brushless DC motor for the joint of a certain type of industrial collaborative robotic arm as an example, the specific working process of the present invention is explained. The rated power of the motor is 10 kilowatts, the rated speed is 3,000 revolutions per minute, and the stator is fixed by a tenon and slot snap-fit ​​structure.

[0054] When the motor is powered on and enters the zero-speed standby state, the clearance identification module injects a high-frequency micro-amplitude alternating test current of 1 kHz and 2 kHz superimposed into the cross-axis command channel. The system extracts the time delay in the high-frequency response of the phase current, separates the influence of electrical parasitic parameters, calculates the pure mechanical delay time, and quantifies the initial physical clearance of the current tenon and groove structure as 0.15 mm based on the offline stiffness model.

[0055] When the robotic arm executes a gripping action that generates a sudden load command, the time derivative of the torque command reaches 30 N·m per millisecond. The graded preload module determines that this value exceeds the preset threshold of 20 N·m per millisecond and directly activates the electromagnetic bias control branch. The system injects a pulse-like transient pressure current into the direct axis, which excites radial electromagnetic force to press the stator connecting rod against the bearing surface. Then, the quadrature axis current limiting is released. Through rigid contact, mechanical impact caused by the instantaneous clearance closure when the step torque is applied is avoided. If the derivative of the robotic arm's smooth transfer task command is lower than the threshold, the system activates the thermal expansion control branch and injects a reactive heating current of 20% of the rated current. Within two seconds, the connecting rod thermally expands by 0.15 mm, achieving flexible clearance filling.

[0056] During continuous high-load operation, the condition monitoring module superimposes orthogonal high-frequency voltage carriers on the base voltage command, extracts the admittance phase angles of the direct axis and quadrature axis, and reconstructs and generates the current tenon groove micro-strain index. When the system detects that the electromagnetic excitation frequency falls within the resonant bandwidth of the stator's natural frequency, the adaptive adjustment module generates in-phase harmonic currents of the same frequency for physical cancellation. Once the tenon groove micro-strain index exceeds the warning threshold, the internal neural network prediction unit immediately outputs a derating coefficient of 0.8, forcibly reducing the steady-state amplitude of the quadrature axis current to prevent the structural components from yielding.

[0057] To verify the reliability and actual technical effect of the present invention, a comparative test was conducted on a motor dynamometer bench. The test objects were divided into two groups: the control group was a coggingless motor of the same model using a traditional control strategy; the experimental group was a motor equipped with the complete control architecture of the present invention. Both groups of motors were subjected to the same step rated load and operated near the calibrated resonant frequency band.

[0058] Table 1: Comparison of Motor Operating Parameters under Step Load and Resonance Conditions - Test Results Based on Table 1 and Figure 9 , 10 The experimental test data of 11 show that after the introduction of the graded preload module, the torque overshoot and stator vibration acceleration peak of the experimental group motor under step load conditions both decreased significantly. This proves that actively eliminating the initial physical clearance suppresses hard collisions of mechanical assembly surfaces. At the same time, the combined effect of the condition monitoring and adaptive adjustment module controls the peak value of the micro-strain index in the resonance zone within a safe range. This confirms that the anti-phase harmonic injection and dynamic torque derating strategies can accurately intervene in local stress concentration phenomena, significantly extend the mechanical fatigue life of the motor, and improve the system safety of high-frequency dynamic operation.

[0059] Working principle: The high-power slotless permanent magnet brushless DC motor provided by this invention operates in coordination based on the physical structure of tenon and slot interlocking. The base 1 supports the entire motor body, the junction box 4 introduces external electrical connections, the outer shell 2 encloses the internal structure and is equipped with heat sink 3 for heat dissipation, the stator core 8 provides a closed magnetic circuit, and the stator winding 6 generates a rotating magnetic field after being energized to drive the squirrel-cage rotor 5 to rotate, and then outputs power to the outside through the shaft 7. The first connecting rod 9 at the end of the stator winding 6 and the second connecting rod 10 inside the housing 2 form a tenon-and-groove locking structure through the limiting cooperation of the fixing post 11, fixing hole 12, sliding groove 13 and pin 14. In the zero-speed standby stage when the motor is not started, the clearance identification module 101 is activated and injects a small alternating current into the stator winding 6. By analyzing the phase current response signal, the pure mechanical delay time is calculated, and the initial physical clearance of the locking part is quantified, providing accurate basic boundary parameters for subsequent actions.

[0060] When the motor receives a torque command and prepares to start or respond to the load, the graded preload module 102 calculates the time derivative of the command in real time to obtain the load step rate, and selects a differentiated preload strategy accordingly to eliminate the physical backlash. When the load changes gradually, the graded preload module 102 controls the direct shaft to inject reactive heating current, and uses the Joule heat generated by the stator winding 6 to induce thermal expansion displacement of the first connecting rod 9, causing it to slowly extend and flexibly fill the gap. When facing a sudden change in highly dynamic operating conditions, the graded preload module 102 controls the direct shaft to inject transient pressure current, which excites unidirectional radial electromagnetic attraction, and instantly forces the first connecting rod 9 to press against the bearing surface of the second connecting rod 10 to form a rigid contact. After completely eliminating the mechanical collision dead zone, the system unlocks the restrictions and officially releases the quadrature shaft torque current to drive the rotor to run.

[0061] After the motor enters the continuous operation stage, the condition monitoring module 103 and the adaptive adjustment module 104 work together in real time to ensure structural safety. The condition monitoring module 103 superimposes a high-frequency voltage carrier on the control command and calculates the tenon groove micro-strain index to characterize the real-time stress state and geometric eccentricity of the structure by extracting the admittance phase angle characteristics of the phase current. After receiving the index, the adaptive adjustment module 104 performs dual protection: on the one hand, it dynamically monitors the resonance risk and injects anti-phase harmonic current compensation into the quadrature axis within the critical bandwidth to actively counteract the mechanical excitation force with electromagnetic pulsation; on the other hand, when the micro-strain index exceeds the safety warning threshold, the adaptive adjustment module 104 forcibly reduces the steady-state amplitude limit of the quadrature axis current to reduce mechanical shear stress by reducing the output thrust. After the strain falls back to the safe area, the limit is smoothly released to completely avoid mechanical damage to the motor under high operating conditions.

[0062] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-power slotless permanent magnet brushless DC motor with tenon-and-groove snap-fit ​​winding connection, comprising a base (1), characterized in that, The base (1) is fixedly connected to an outer shell (2), and a heat sink (3) is provided on the outer shell (2). A junction box (4) is fixedly connected to the outer shell (2). A rotating shaft (7) is rotatably connected to the inner side of the outer shell (2). A cage rotor (5) is fixedly connected to the outer side of the rotating shaft (7). A stator core (8) is fixedly connected to the inner side of the outer shell (2). A stator winding (6) is provided on the outer side of the cage rotor (5). A second connecting rod (10) is fixedly connected to the inner side of the outer shell (2). One end of the sub-winding (6) is fixedly connected to a first connecting rod (9). The second connecting rod (10) and the first connecting rod (9) are both provided with fixing holes (12). The second connecting rod (10) and the first connecting rod (9) are both provided with sliding grooves (13). The first connecting rod (9) and the second connecting rod (10) are both fixedly connected to fixing posts (11). The fixing posts (11) are slidably connected to the inside of the fixing holes (12). The sliding grooves (13) are slidably connected to the outside of the pins (14). The junction box (4) is fixedly connected to the top with a clearance identification module (101), which is used to inject dual-frequency micro-amplitude alternating current. The junction box (4) is fixedly connected to the top with a graded pre-tightening module (102), which is used to calculate the time derivative of the externally input torque command in real time. The junction box (4) is fixedly connected to the outside with a state monitoring module (103), which is used to extract the admittance phase angle and calculate the tenon groove micro-strain index. The junction box (4) is fixedly connected to the outside with an adaptive adjustment module (104), which is used to counteract the physical excitation force and forcibly reduce the steady-state amplitude limit of the quadrature axis current.

2. The high-power slotless permanent magnet brushless DC motor with tenon-and-groove snap-fit ​​winding connection according to claim 1, characterized in that, The clearance identification module (101) integrates a signal generation unit. The test current signal injected by the signal generation unit into the quadrature axis current command channel is a linear superposition of a sine wave with a first high-frequency carrier angular frequency and a sine wave with a second high-frequency carrier angular frequency. The amplitude of the alternating test current signal is controlled below the set threshold corresponding to the static friction torque of the motor to isolate the coupling superposition of back electromotive force.

3. The high-power slotless permanent magnet brushless DC motor with tenon-and-groove snap-fit ​​winding connection according to claim 2, characterized in that, The gap identification module (101) integrates a differential calculation unit and a gap quantization unit. The differential calculation unit extracts the total phase delay time and subtracts the product of the first high-frequency carrier angle frequency and the total phase delay time from the product of the second high-frequency carrier angle frequency and the corresponding total phase delay time. The calculated difference is divided by the difference between the second high-frequency carrier angle frequency and the first high-frequency carrier angle frequency, thereby constructing a differential equation to cancel the electrical delay time term and obtain the pure mechanical delay time term. The clearance quantization unit multiplies the pure mechanical delay time by the offline fitted clearance stiffness conversion coefficient to convert it into the initial physical clearance in the spatial dimension.

4. The high-power slotless permanent magnet brushless DC motor with tenon-and-groove snap-fit ​​winding connection according to claim 1, characterized in that, The graded pre-tightening module (102) integrates an instruction derivative calculator, a state comparator, a thermal expansion control branch, and an electromagnetic bias control branch. The state comparator compares the time derivative with a preset step rate determination threshold. When the time derivative is lower than the step rate determination threshold, the thermal expansion control branch is activated to respond to a state of slow acceleration or low dynamic response. When the time derivative is higher than or equal to the step rate determination threshold, the electromagnetic bias control branch is activated to respond to a high dynamic operating condition.

5. The high-power slotless permanent magnet brushless DC motor with tenon-and-groove snap-fit ​​winding connection according to claim 4, characterized in that, The thermal expansion control branch continuously injects controlled reactive heating current into the direct axis current channel according to the initial physical clearance. The Joule heat generated in the stator winding (6) triggers the thermal expansion displacement of the first connecting rod (9). The extension of the thermal expansion displacement of the first connecting rod (9) gradually closes in space and fills the existing initial physical clearance, thereby achieving flexible fit. The electromagnetic bias control branch injects transient pressure current into the direct axis, which excites a unidirectional transient radial electromagnetic attraction force equal to the clearance stiffness resistance, forcibly pressing the first connecting rod (9) at the end of the stator winding (6) onto the bearing surface of the second connecting rod (10) to form a rigid contact state.

6. The high-power slotless permanent magnet brushless DC motor with tenon-and-groove snap-fit ​​winding connection according to claim 1, characterized in that, The status monitoring module (103) integrates a high-frequency carrier modulator and a heterodyne demodulator. The high-frequency carrier modulator superimposes in real time the orthogonal high-frequency voltage carrier with constant frequency and amplitude and maintaining an orthogonal differential relationship in spatial phase onto the basic magnetic field orientation control voltage command. The heterodyne demodulator uses the orthogonal phase-locked loop demodulation algorithm to heterodyne the extracted actual high-frequency response current and the local reference carrier, and attenuates the second harmonic component through a low-pass filter. It then calculates the imaginary and real components of the extracted high-frequency current through arctangent calculation logic to obtain the direct-axis high-frequency admittance phase angle and the quadrature-axis high-frequency admittance phase angle.

7. The high-power slotless permanent magnet brushless DC motor with tenon-and-groove snap-fit ​​winding connection according to claim 6, characterized in that, The state monitoring module (103) also integrates a feature reconstruction unit. The feature reconstruction unit subtracts the phase angle of the direct-axis high-frequency admittance from the phase angle of the quadrature-axis high-frequency admittance and deducts the absolute value of the static phase angle offset. Then, it multiplies the absolute value by the sensitivity amplification factor calibrated offline to reconstruct the tenon groove micro-strain index, so as to characterize the real-time stress state and geometric eccentricity of the tenon groove snap-fit ​​structure during operation.

8. The high-power slotless permanent magnet brushless DC motor with tenon-and-groove snap-fit ​​winding connection according to claim 1, characterized in that, The adaptive adjustment module (104) integrates a harmonic suppression unit. The harmonic suppression unit has a built-in dynamic mapping table of the stator structure's natural frequency with respect to the tenon groove micro-strain index. When it detects that the electromagnetic excitation frequency extracted by the fast Fourier transform has entered the resonance critical bandwidth of the corrected stator structure's real-time natural frequency, it superimposes an anti-phase harmonic current compensation amount with the same frequency and amplitude and a phase difference of 180 degrees onto the quadrature axis current command to eliminate the electromagnetic torque fluctuation caused by the stator current harmonics, thereby actively offsetting the mechanical excitation force that causes resonance at the physical level.

9. The high-power slotless permanent magnet brushless DC motor with tenon-and-groove snap-fit ​​winding connection according to claim 8, characterized in that, The adaptive adjustment module (104) also integrates a state evaluation unit, a neural network prediction unit, and an instruction correction unit. The neural network prediction unit is equipped with a three-layer feedforward neural network model. The three-layer feedforward neural network model maps the current tenon groove micro-strain index, rotor mechanical speed and direct axis current through the minimum maximum normalization algorithm as a three-dimensional feature input vector, and propagates forward to calculate and output the dynamic torque derating coefficient. The instruction correction unit performs an algebraic multiplication operation on the dynamic torque derating coefficient and the quadrature axis torque current instruction, and linearly superimposes the anti-phase harmonic current compensation amount to generate the reconstructed final quadrature axis torque current instruction, which is then sent to the current closed-loop regulator.

10. The high-power slotless permanent magnet brushless DC motor with tenon-and-groove snap-fit ​​winding connection according to claim 9, characterized in that, When the state assessment unit detects that the micro-strain index of the tenon groove falls below the recovery dead zone set by the elastic deformation warning threshold, the neural network prediction unit stops outputting actions, the command correction unit linearly restores the dynamic torque derating coefficient to the initial value according to the preset smooth slope and releases the system torque limit, and the adaptive adjustment module (104) continuously sends the reconstructed quadrature axis torque current command as the update reference to the current closed-loop regulator.

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