Permanent magnet synchronous driving assembly with speed change function

Abstract

The invention provides a permanent magnet synchronous driving assembly with a speed change function. The permanent magnet synchronous driving assembly comprises a hybrid excitation motor, a speed reducer, a dual-channel inverter, a controller and a sensing network, the hybrid excitation motor comprises a stator and a rotor which are provided with fractional slot windings, the rotor is sequentially provided with a permanent magnet array, an isolation layer and an excitation winding array which are sequentially distributed in the axial direction of the rotor from the axis to the outside, the permanent magnet array is formed by splicing a plurality of fan-shaped magnetic steel, and N poles and S poles are alternately arranged to form main magnetic field pole pairs; the number of excitation windings of the excitation winding array is half of that of the magnetic steel, each winding is embedded between adjacent pole pairs, and the axes of the excitation windings and the axes of the magnetic poles of the permanent magnets are deviated by a certain angle to form a space phase difference; a permanent magnet magnetic circuit formed by the permanent magnet array and the stator and an electric excitation magnetic circuit formed by the excitation winding array and the stator are subjected to vector superposition at an air gap; the dual-channel inverter comprises a main power channel and an excitation channel.

Description

Technical Field

[0001] The present invention relates to the technical field of motor drive, and particularly to a permanent magnet synchronous drive assembly with a variable speed function. Background Art

[0002] The permanent magnet synchronous drive assembly is a high-efficiency and high-power density power system, which is widely used in fields such as electric vehicles, industrial drives, and rail transit. Its variable speed function is realized through power electronic control technology, and has advantages such as fast dynamic response, high efficiency, and small volume. The permanent magnet synchronous drive assembly with a speed reducer has the characteristics of high-efficiency operation, low loss, and high torque output.

[0003] The permanent magnet synchronous drive assembly consists of a permanent magnet synchronous motor, a speed reducer, an inverter, a controller, a sensor system, and a cooling system, etc. Among them, the core components of the permanent magnet synchronous motor are the stator and the rotor. Energy conversion is achieved through magnetic field synchronization to drive the rotor to rotate. The inverter converts direct current into alternating current with variable frequency and variable amplitude, and controls the output voltage and frequency through pulse width modulation technology, thereby adjusting the motor speed. The controller, based on the control algorithm, receives sensor signals in real time and adjusts the output parameters of the inverter. The speed reducer is used to reduce the speed and increase the torque.

[0004] The reason why the variable speed function can be realized is that by controlling the input electrical frequency and voltage amplitude of the motor, the synchronous speed of the rotating magnetic field is adjusted. According to the formula of speed and frequency, the controller can directly change the motor speed by adjusting the output frequency through the inverter. In the field weakening speed regulation range, by adjusting the voltage phase angle and weakening the magnetic field strength, constant power wide speed range operation can be achieved. Finally, the sensor monitors the rotor position in real time, and the controller dynamically compensates for load fluctuations to ensure that the speed accurately tracks the command value.

[0005] However, the permanent magnet is prone to irreversible demagnetization under high temperature or strong demagnetizing field, which affects its lifespan. Because the magnetism of the permanent magnet comes from the directional arrangement of internal magnetic domains. When the temperature exceeds a certain threshold, the stable arrangement of magnetic domains is destroyed. The magnetization state of the permanent magnet is described by its hysteresis loop. When a reverse magnetic field is applied, the magnetic induction intensity decreases along the loop. If the reverse magnetic field strength exceeds the coercivity of the material, the magnetization state will cross the "knee point" of the loop and enter the irreversible stage. At this time, even if the reverse magnetic field is removed, the magnet cannot recover its original remanence. Summary of the Invention

[0006] The present invention aims to solve the above technical problems and provides a permanent magnet synchronous drive assembly with a variable speed function.

[0007] The technical solution of the present invention is that a permanent magnet synchronous drive assembly with a variable speed function includes a hybrid excitation motor, a speed reducer, a dual-channel inverter, a controller, and a sensing network; The hybrid excitation motor includes a stator and a rotor with a fractional-slot winding. The rotor is provided, from the axis outward, with a permanent magnet array, an isolation layer, and an exciting winding array that are also distributed in sequence along the axial direction of the rotor. The permanent magnet array is composed of multiple sector-shaped magnets spliced together, with N poles and S poles arranged alternately to form main magnetic field pole pairs. The number of exciting windings in the exciting winding array is half the number of magnets, and each winding is respectively embedded between adjacent pole pairs. The axis of the exciting winding is offset by a certain angle from the axis of the permanent magnet pole to form a spatial phase difference. The permanent magnetic circuit formed by the permanent magnet array and the stator is vectorially superposed with the electric excitation magnetic circuit formed by the exciting winding array and the stator at the air gap. The dual-channel inverter includes a main power channel for driving the stator winding and an exciting channel for supplying power to the rotor exciting winding through brushes and slip rings. The sensing network includes a current detection unit, a voltage detection unit, an encoder, a fiber Bragg grating sensor, and a magnetoresistive sensor. The current detection unit is used to detect the three-phase current of the inverter output. The voltage detection unit is used to detect the DC bus voltage. The encoder is used to detect the position and speed of the rotor. The fiber Bragg grating sensor is embedded inside the permanent magnet array to detect the magnet temperature. The magnetoresistive sensor is arranged at the air gap to detect the synthetic magnetic field vector.

[0008] As an implementation, the speed reducer is a two-stage planetary speed reducer. The first-stage planetary transmission structure of the speed reducer is connected to the hybrid excitation motor, and the second-stage planetary transmission structure of the speed reducer is connected to the load.

[0009] As an implementation, the isolation layer is wound into a ring shape using nanocrystalline strip, and is continuously wound along the circumferential direction of the ring in a spiral involute trajectory. Each turn of the strip is offset relative to the previous turn, so that multiple turns of the strip are offset and stacked in a stepped manner.

[0010] As an implementation, after every 5 layers of the strip are wound, a magnesium oxide insulating layer is sprayed to form an insulating barrier perpendicular to the axial direction.

[0011] As an implementation, the magnets are arranged in segments along the axial direction of the rotor.

[0012] As an implementation, non-magnetic ribs are provided between adjacent N-pole and S-pole magnets to limit circumferential magnetic leakage.

[0013] As an implementation, the controller configures the following dynamic control strategy: Through the EKF algorithm, based on the input three-phase current, DC bus voltage, rotor position, rotor speed, and magnet temperature, the remanence of the permanent magnet array is estimated online, and the current remanence and remanence attenuation are output. Dynamically adjust the electro-excitation current output by the excitation channel according to the magnet temperature, current residual magnetism, synthetic magnetic field vector, residual magnetism attenuation, and load demand; Among them, when the magnet temperature is greater than the temperature safety value, start the reverse excitation current to weaken the synthetic magnetic field intensity, and set the amplitude of the excitation current according to the critical demagnetization magnetic field intensity; When the demagnetization magnetic field intensity is greater than the critical demagnetization magnetic field intensity, increase the reverse excitation current until the demagnetization magnetic field intensity is less than the critical demagnetization magnetic field intensity; When the magnet temperature is less than the temperature safety value and the demagnetization magnetic field intensity is less than the critical demagnetization magnetic field intensity, turn off the reverse excitation current; When there is residual magnetism attenuation or the load demand increases, increase the forward excitation current to enhance the synthetic magnetic field intensity; Among them, the critical demagnetization magnetic field intensity is calculated according to the real-time magnet temperature, and the demagnetization magnetic field intensity is calculated according to the current residual magnetism and the synthetic magnetic field vector.

[0014] As an implementation method, the priority of using the demagnetization magnetic field intensity alone as the execution condition is greater than the priority of using the magnet temperature alone as the execution condition, and the priority of using the magnet temperature alone as the execution condition is greater than the priority of using other conditions as the execution condition.

[0015] As an implementation method, the speed reducer includes a housing, the first-stage planetary transmission structure and the second-stage planetary transmission structure are built in the housing, the first-stage planetary transmission structure includes a first sun gear, a first planetary gear, a first planetary carrier, and a first internal gear ring; the first sun gear is connected to the hybrid excitation motor, the first internal gear ring is fixed to the housing, and the first planetary gear is installed on the first planetary carrier and is located between the first sun gear and the first internal gear ring; The second-stage planetary transmission structure includes a second sun gear, a second planetary gear, a second planetary carrier and a second internal gear ring; the second sun gear is connected to the first planetary carrier, the second internal gear ring is fixed to the housing, the second planetary gear is installed on the second planetary carrier and is located between the second sun gear and the second internal gear ring, and the second planetary carrier is used to connect the load.

[0016] As an implementation method, the number of the first planetary gears is set to 4, and the number of the second planetary gears is set to 3.

[0017] The beneficial effects of the present invention compared with the prior art are as follows. The permanent magnet synchronous drive assembly with variable speed function is designed to overcome the problem of irreversible demagnetization that traditional permanent magnet synchronous drive assemblies are prone to under high temperature or strong demagnetizing fields, and at the same time achieve the collaborative optimization of magnetic field, thermal field, and force field at the system level. It is an electric drive system with high-reliability variable speed function. The permanent magnet synchronous drive assembly with variable speed function reconstructs the traditional permanent magnet synchronous drive assembly through the collaborative excitation structure of "permanent magnet + auxiliary excitation winding". While retaining the high-efficiency advantage of the permanent magnet, it introduces a dynamically adjustable electromagnetic compensation magnetic field to form a four-dimensional linkage system-level solution. In terms of the motor, a hybrid excitation motor is used, in which the rotor topology is innovated to make the rotor have a composite magnetic circuit structure of "axial stratification + circumferential staggering". In terms of the inverter, a dual-channel inverter is used, which are the main power channel and the excitation channel respectively. In terms of the controller, the controller estimates the remanence of the permanent magnet array in real time through the extended Kalman filter (EKF algorithm). The controller optimizes the magnetic field ratio provided by the permanent magnet and the electric excitation respectively according to the load demand and the feedback of the magnet temperature. In terms of the sensing network, a current detection unit, a voltage detection unit, an encoder, a fiber Bragg grating sensor, and a magnetoresistive sensor are set. The current detection unit is used to detect the three-phase current of the inverter output, the voltage detection unit is used to detect the DC bus voltage, the encoder is used to detect the position and speed of the rotor, the fiber Bragg grating sensor is embedded inside the permanent magnet array to detect the magnet temperature, and the magnetoresistive sensor is arranged at the air gap to detect the synthetic magnetic field vector. In addition, a speed reducer is combined, so that the permanent magnet synchronous drive assembly has both the high-efficiency operation characteristics brought by power electronic control technology and the high-torque output characteristics brought by mechanical speed change.

[0018] In summary, the permanent magnet synchronous drive assembly with variable speed function forms the above four-dimensional linkage. On the premise of ensuring the safety of the permanent magnet, it fuses the current remanence, synthetic magnetic field vector, and voltage data in real time, dynamically adjusts the excitation current, and realizes the efficient and high-dynamic response operation of the drive system. Brief Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of the hybrid excitation motor of the permanent magnet synchronous drive assembly with variable speed function provided by the embodiment of the present invention; Figure 2 It is a partial structural diagram of the hybrid excitation motor of the permanent magnet synchronous drive assembly provided by the embodiment of the present invention from the first perspective; Figure 3 It is a partial structural diagram of the hybrid excitation motor of the permanent magnet synchronous drive assembly provided by the embodiment of the present invention from the second perspective; Figure 4 It is a system block diagram of the permanent magnet synchronous drive assembly provided by the embodiment of the present invention; Figure 5Schematic structural diagram of two-stage planetary drive inside a speed reducer provided by an embodiment of the present invention.

[0020] In the figure: 1, hybrid excitation motor; 2, stator; 3, rotor; 4, permanent magnet array; 5, isolation layer; 6, excitation winding array; 7, magnetic steel; 8, excitation winding; 9, non-magnetic rib; 10, speed reducer; 11, housing; 12, first-stage planetary drive structure; 13, second-stage planetary drive structure; 14, first sun gear; 15, first planet gear; 16, first planet carrier; 17, first internal gear ring; 18, second sun gear; 19, second planet gear; 20, second planet carrier; 21, second internal gear ring. Specific embodiments

[0021] The following will clearly and completely describe the above and other embodiments and advantages of the present invention with reference to the accompanying drawings. Obviously, the described embodiments are only some, rather than all, of the embodiments of the present invention.

[0022] In one embodiment, as Figures 1 to 4 shown.

[0023] The permanent magnet synchronous drive assembly with variable speed function provided by this embodiment is equipped with a speed reducer 10, which includes a hybrid excitation motor 1, a dual-channel inverter, a controller, and a sensing network. The hybrid excitation motor 1 includes a stator 2 with a fractional-slot winding and a rotor 3. The rotor 3 is successively provided with a permanent magnet array 4, an isolation layer 5, and an excitation winding array 6 from the axis outward, and the permanent magnet array 4, the isolation layer 5, and the excitation winding array 6 are also successively distributed along the axial direction of the rotor 3. The permanent magnet array 4 is spliced by multiple sector-shaped magnetic steels 7, and the N poles and S poles are alternately arranged along the circumferential direction to form main magnetic field pole pairs. The number of excitation windings 8 in the excitation winding array 6 is half of the number of magnetic steels 7, and each winding is respectively embedded between adjacent main magnetic field pole pairs. The axis of the excitation winding 8 is offset at a certain angle from the axis of the permanent magnet pole to form a spatial phase difference. The permanent magnet magnetic circuit formed by the permanent magnet array 4 and the stator 2 and the electric excitation magnetic circuit formed by the excitation winding array 6 and the stator 2 are vectorially superimposed at the air gap. The dual-channel inverter includes a main power channel for driving the stator winding and an excitation channel for supplying power to the rotor excitation winding 8 through brushes and slip rings. The sensing network includes a current detection unit, a voltage detection unit, an encoder, a fiber Bragg grating sensor, and a magnetoresistive sensor. The current detection unit is used to detect the three-phase current of the inverter output, the voltage detection unit is used to detect the DC bus voltage, the encoder is used to detect the position and speed of the rotor 3, the fiber Bragg grating sensor is embedded inside the permanent magnet array 4 to detect the temperature of the magnetic steel, and the magnetoresistive sensor is arranged at the air gap to detect the synthetic magnetic field vector. The controller configures the following dynamic control strategies: Through the EKF algorithm, based on the input three-phase current, DC bus voltage, rotor position, rotor speed, and magnetic steel temperature, online estimate the residual magnetism of the permanent magnet array, and output the current residual magnetism and residual magnetism attenuation. According to the magnetic steel temperature, current residual magnetism, synthetic magnetic field vector, residual magnetism attenuation, and load demand, dynamically adjust the electric excitation current output by the excitation channel.

[0024] In this embodiment, the permanent magnet synchronous drive assembly with variable speed function is designed to overcome the irreversible demagnetization problem that traditional permanent magnet synchronous drive assemblies are prone to under high temperature or strong demagnetizing fields, and at the same time achieve the collaborative optimization of the magnetic field, thermal field, and force field at the system level, and is an electric drive system with a high-reliability variable speed function.

[0025] The permanent magnet synchronous drive assembly with variable speed function reconstructs the traditional permanent magnet synchronous drive assembly through a "permanent magnet + auxiliary excitation winding" collaborative excitation structure. While retaining the high efficiency advantage of the permanent magnet, it introduces a dynamically adjustable electromagnetic compensation magnetic field to form a four-dimensional linkage system-level solution. The four-dimensional linkage is reflected in the improvement of the motor, the improvement of the inverter, the improvement of the controller, and the improvement of the sensing network.

[0026] In terms of the motor, a hybrid excitation motor 1 is used, in which the topology of the rotor 3 is innovated to make the rotor 3 have an "axial layer + circumferential stagger" composite magnetic circuit structure.

[0027] The inner layer of the rotor 3 is a permanent magnet array 4, which can be a V-shaped neodymium iron boron permanent magnet array (12 poles), embedded in the slots of high-permeability silicon steel sheets. The outer layer of the rotor 3 is an exciting winding array 6, which can be a distributed copper exciting winding array (6 poles), and is connected to an external exciting power supply through slip rings and brushes. A magnetic barrier layer, that is, an isolation layer 5, is arranged between the inner layer and the outer layer of the rotor 3. It can be a nanocrystalline alloy isolation ring, which is arranged between the permanent magnet layer and the exciting layer to achieve magnetic circuit decoupling. The above-mentioned inner layer of the rotor, the magnetic barrier layer, and the outer layer of the rotor are radially stratified. Axially, the inner layer of the rotor is simultaneously the axial bottom layer, the magnetic barrier layer is simultaneously the axial middle layer, and the outer layer of the rotor is simultaneously the axial top layer. This is the magnetic circuit structure of the rotor 3 with "axial stratification".

[0028] On the circumferential circle of the rotor 3, a permanent magnet module is arranged every 60° mechanical angle (corresponding to a 12-pole motor), that is, a main magnetic field pole pair with N and S poles is formed. An exciting slot is embedded between adjacent pole pairs, and an exciting winding 8 is arranged in the exciting slot. The axis of the exciting winding 8 is offset by 30° (or other mechanical angles) from the axis of the permanent magnet pole to form a spatial phase difference. This is the magnetic circuit structure of the rotor 3 with "circumferential stagger".

[0029] The path of the permanent magnet magnetic circuit is permanent magnet N pole → rotor magnetic yoke → stator → rotor magnetic yoke → permanent magnet S pole. The path of the electric excitation magnetic circuit is exciting winding N pole → magnetic barrier layer → air gap → stator → air gap → magnetic barrier layer → exciting winding S pole. The two magnetic circuits are vectorially superimposed at the air gap. By adjusting the direction and amplitude of the exciting current, the following can be achieved: Magnetization enhancement mode (the exciting current is in the same direction as the permanent magnetic field): Improve the air gap magnetic density and enhance the output torque. Field weakening mode (the exciting current is in the opposite direction to the permanent magnetic field): Broaden the constant power speed regulation range and suppress the demagnetization of the permanent magnet. And zero excitation mode (the exciting current is zero): Turn off the electric excitation to reduce losses.

[0030] In terms of the inverter, a dual-channel inverter is used, which are the main power channel and the exciting channel respectively. The main power channel is a three-phase full-bridge circuit based on thyristors, used to drive the stator winding. The exciting channel is an independent H-bridge topology, which outputs an adjustable DC voltage of 0 - 48V and supplies power to the rotor exciting winding 8 through brushes and slip rings.

[0031] In terms of the controller, the controller estimates the remanence of the permanent magnet array in real time through the extended Kalman filter (EKF algorithm), and this EKF algorithm can predict the gradual attenuation of the remanence. The controller establishes an exponential relationship between the temperature of the permanent magnet and the critical demagnetization magnetic field. Thus, by inputting the real-time temperature of the permanent magnet, the corresponding critical demagnetization magnetic field strength can be calculated according to the exponential relationship. The controller optimizes the magnetic field ratio provided by the permanent magnet and the electric excitation respectively according to the load demand and the feedback of the permanent magnet temperature.

[0032] In the aspect of the sensing network, a current detection unit, a voltage detection unit, an encoder, a fiber Bragg grating sensor, and a magnetoresistive sensor are provided. The current detection unit is used to detect the three-phase current of the inverter output. The voltage detection unit is used to detect the DC bus voltage. The encoder is used to detect the position and speed of the rotor 3. The fiber Bragg grating sensor is embedded inside the permanent magnet array 4 to detect the temperature of the permanent magnet. The magnetoresistive sensor is arranged at the air gap to detect the synthetic magnetic field vector.

[0033] In this embodiment, the permanent magnet synchronous drive assembly with variable speed function forms the above four-dimensional linkage. On the premise of ensuring the safety of the permanent magnet, the current residual magnetism and the synthetic magnetic field vector are fused in real time, and the excitation current is dynamically adjusted to achieve the efficient and high dynamic response operation of the drive system.

[0034] In this embodiment, the reducer 10 of the permanent magnet synchronous drive assembly with variable speed function is a reducer including a first planetary gear and a second planetary gear, thus forming a two-stage planetary transmission structure. At present, based on the two-stage planetary transmission structure and the existing shift structure, the gear shift function can be realized mechanically. When the two-stage reducer works simultaneously, it outputs low speed and large torque, which is suitable for the load condition. When only the second-stage reducer works, it outputs high speed and small torque, which is suitable for rapid movement without load. When neither the first-stage reducer nor the second-stage reducer works, the transmission components rotate freely and there is no power output, which is suitable for towing or fault traction.

[0035] In one embodiment, as Figure 4 shown.

[0036] For the permanent magnet synchronous drive assembly with variable speed function provided in this embodiment, the dynamic control strategy for the controller to dynamically adjust the electro-excitation current output by the excitation channel according to the permanent magnet temperature, the current residual magnetism, the synthetic magnetic field vector, the residual magnetism attenuation, and the load demand is as follows: when the permanent magnet temperature is greater than the temperature safety value, start the reverse excitation current to weaken the synthetic magnetic field intensity, and set the amplitude of the excitation current according to the critical demagnetization magnetic field intensity; when the demagnetization magnetic field intensity is greater than the critical demagnetization magnetic field intensity, increase the reverse excitation current until the demagnetization magnetic field intensity is less than the critical demagnetization magnetic field intensity; when the permanent magnet temperature is less than the temperature safety value and the demagnetization magnetic field intensity is less than the critical demagnetization magnetic field intensity, turn off the reverse excitation current; when there is residual magnetism attenuation or the load demand increases, increase the forward excitation current to enhance the synthetic magnetic field intensity; wherein, the critical demagnetization magnetic field intensity is calculated according to the real-time permanent magnet temperature, and the demagnetization magnetic field intensity is calculated according to the current residual magnetism and the synthetic magnetic field vector. The current residual magnetism is obtained from the EKF estimator, and the synthetic magnetic field vector is obtained from the magnetoresistive sensor.

[0037] In this embodiment, when the temperature of the permanent magnet is greater than the temperature safety value, a reverse excitation current is started to weaken the synthetic magnetic field intensity, and the amplitude of the excitation current is set according to the critical demagnetization magnetic field intensity. This is the over-temperature protection. The trigger condition is that the temperature of the permanent magnet is greater than the temperature safety value (which can be 120 °C). The response action is to start the reverse excitation current to weaken the synthetic magnetic field intensity. At the same time, the critical demagnetization magnetic field intensity is calculated based on the exponential relationship between the temperature of the permanent magnet and the critical demagnetization magnetic field, and the amplitude of the excitation current is set according to the critical demagnetization magnetic field intensity. At the same time, the output torque can also be reduced. When the demagnetization magnetic field intensity is greater than the critical demagnetization magnetic field intensity, the reverse excitation current is increased until the demagnetization magnetic field intensity is less than the critical demagnetization magnetic field intensity. This is the protection against excessive demagnetization magnetic field. The trigger condition is that the demagnetization magnetic field intensity is greater than the critical demagnetization magnetic field intensity. The response action is to increase the reverse excitation current until the demagnetization magnetic field intensity is less than the critical demagnetization magnetic field intensity. At the same time, the maximum speed of the motor can also be limited. When the temperature of the permanent magnet is less than the temperature safety value and the demagnetization magnetic field intensity is less than the critical demagnetization magnetic field intensity, the reverse excitation current is turned off. This is the efficiency optimization. The trigger condition is that the temperature of the permanent magnet is less than the temperature safety value and the demagnetization magnetic field intensity is less than the critical demagnetization magnetic field intensity. The response action is to turn off the electric excitation to maximize the utilization rate of the permanent magnet. At the same time, the inverter modulation strategy can also be adjusted to reduce the switching loss. When there is residual magnetism attenuation or an increase in load demand, the forward excitation current is increased to enhance the synthetic magnetic field intensity and the output torque. This is the performance optimization.

[0038] In this embodiment, the permanent magnet synchronous drive assembly with variable speed function ensures the safety of the permanent magnet, and in real-time integrates the current residual magnetism and synthetic magnetic field vector, dynamically adjusts the excitation current, and realizes the efficient and high dynamic response operation of the drive system. At the same time, the collaborative optimization of the magnetic field, thermal field, and force field is realized at the system level.

[0039] In one embodiment, as Figure 4 shown.

[0040] For the permanent magnet synchronous drive assembly with variable speed function provided in this embodiment, the priority of using the demagnetization magnetic field intensity alone as the execution condition is greater than the priority of using the temperature of the permanent magnet alone as the execution condition, and the priority of using the temperature of the permanent magnet alone as the execution condition is greater than the priority of using other conditions as the execution condition.

[0041] In this embodiment, the priority is demagnetization protection > temperature protection > efficiency optimization and performance optimization. For the handling of conflicts, when high temperature and strong demagnetization magnetic field occur simultaneously, reverse excitation is preferentially executed and the power is reduced.

[0042] In one embodiment, as Figure 4 shown.

[0043] The steps for online estimating the residual magnetism of the permanent magnet array in the permanent magnet synchronous drive assembly with variable speed function provided by this embodiment include: Prediction step: Predict the current residual magnetism state according to the previous moment's residual magnetism state and the motor dynamic model. Update step: Use the real-time measured three-phase current, rotor 3 speed, and magnet temperature to correct the predicted value.

[0044] In this embodiment, the motor has its own dynamic model, which involves state vectors, input voltage, and process noise. The EKF algorithm is based on the motor dynamic model and outputs the current estimated value of residual magnetism. And by using the temperature-magnetic field (rotor speed)-current triangular relationship, the predicted value can be corrected. Further, when the difference generated by the magnetic field intensity of the current residual magnetism feedback and the magnetic field intensity of the synthesized magnetic field vector feedback is greater than the threshold, the correction parameter is corrected. The current residual magnetism is estimated and corrected by the EKF algorithm, and the synthesized magnetic field vector is detected by the magnetoresistive sensor. By using the difference between the two, the correction parameter of the EKF model is corrected, and the two complement each other. The EKF can predict the gradual attenuation, and the magnetoresistive sensor can capture the sudden magnetic field distortion. At the same time, the detection of the magnetoresistive sensor is also a verification of the magnetic field state.

[0045] In one embodiment, as Figure 2 and Figure 3 shown.

[0046] For the permanent magnet synchronous drive assembly with variable speed function provided by this embodiment, the isolation layer 5 is wound into a ring shape with nanocrystalline strip, and is continuously wound along the circumferential direction of the ring in a spiral involute trajectory. Each turn of the strip is offset relative to the previous turn, so that multiple turns of the strip are offset and stacked in a stepped manner.

[0047] In this embodiment, the winding angle of the isolation layer 5 adopts a spiral involute trajectory, which can ensure tight fitting between layers. The multi-layer strips are offset and stacked in a stepped manner, which can ensure the maximum contact area between layers, reduce the air gap and magnetic leakage.

[0048] In one embodiment, as Figure 2 and Figure 3 shown.

[0049] For the permanent magnet synchronous drive assembly with variable speed function provided by this embodiment, the strip is sprayed with a magnesium oxide insulating layer every 5 layers of winding to form an insulating barrier perpendicular to the axial direction.

[0050] In this embodiment, the insulating layer can achieve interlayer insulation, that is, spray the nano magnesium oxide insulating layer every 5 layers of winding to form an insulating barrier perpendicular to the axial direction and block the interlayer current.

[0051] In one embodiment, as Figure 3 shown.

[0052] The permanent magnet synchronous drive assembly with variable speed function provided by this embodiment has the magnetic steel 7 arranged in segments along the rotor axis.

[0053] In this embodiment, the magnetic steel 7 is arranged in segments along the rotor axis, and the length of each segment is aligned with the core of the stator 2 to form an independent magnetic circuit module.

[0054] In one embodiment, as Figure 3 shown.

[0055] For the permanent magnet synchronous drive assembly with variable speed function provided by this embodiment, non-magnetic ribs 9 are provided between adjacent N-pole magnetic steels 7 and S-pole magnetic steels 7 to limit circumferential magnetic leakage.

[0056] In this embodiment, the non-magnetic rib 9 can be a titanium alloy rib. Setting non-magnetic titanium alloy ribs between adjacent N-pole magnetic steels 7 and S-pole magnetic steels 7 can limit circumferential magnetic leakage and force the magnetic flux to close along the designed path.

[0057] In one embodiment, as Figure 5 shown.

[0058] The reducer 10 of the permanent magnet synchronous drive assembly with variable speed function provided by this embodiment includes a housing 11 and a first-stage planetary transmission structure 12 and a second-stage planetary transmission structure 13 built into the housing 11. The first-stage planetary transmission structure 12 includes a first sun gear 14, a first planetary gear 15, a first planetary carrier 16, and a first internal gear ring 17. The first sun gear 14 is connected to the hybrid excitation motor 1, the first internal gear ring 17 is fixed to the housing 11, and the first planetary gear 15 is installed on the first planetary carrier 16 and is located between the first sun gear 14 and the first internal gear ring 17. The second-stage planetary transmission structure 13 includes a second sun gear 18, a second planetary gear 19, a second planetary carrier 20, and a second internal gear ring 21. The second sun gear 18 is connected to the first planetary carrier 16, the second internal gear ring 21 is fixed to the housing 11, the second planetary gear 19 is installed on the second planetary carrier 20 and is located between the second sun gear 18 and the second internal gear ring 21, and the second planetary carrier 20 is used to connect to an external load. And, the first planetary gear 15 is provided with 4, and the second planetary gear 19 is provided with 3.

[0059] In this embodiment, a differential layout of 4 planetary gears in the first stage and 3 planetary gears in the second stage is adopted, which realizes a reasonable distribution of two-stage loads while ensuring a compact structure. Through the structural design of the fixed double internal gear rings linked with the planetary carrier, two independent deceleration channels are formed, and the composite amplification effect of the total reduction ratio is achieved with only a 15% increase in the axial space. The unique phase misalignment arrangement of the planetary gears makes the phase difference of the meshing impact force reach 90°, reducing vibration and noise.

[0060] The above specific implementation manners have further elaborated in detail on the invention purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are only the specific implementation manners of the present invention and are not used to limit the protection scope of the present invention. It is particularly pointed out that for those skilled in the art, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A permanent magnet synchronous drive assembly with speed change function, characterized in that: Includes hybrid excitation motor, reducer, dual-channel inverter, controller, and sensor network; The hybrid excitation motor comprises a stator and a rotor configured as a fractional slot winding, wherein the rotor is provided with a permanent magnet array, an isolation layer, and an excitation winding array which are sequentially arranged from the axis to the outside and are also sequentially distributed along the axial direction of the rotor, wherein the permanent magnet array is spliced ​​by a plurality of fan-shaped magnetic steels, and the N poles and the S poles are alternately arranged to form a main magnetic field pole pair; the number of excitation windings of the excitation winding array is half the number of magnetic steels, and each winding is respectively embedded between adjacent pole pairs, the axis of the excitation winding is offset at a certain angle from the axis of the permanent magnet pole to form a spatial phase difference, and the permanent magnet magnetic circuit formed by the permanent magnet array and the stator and the electric excitation magnetic circuit formed by the excitation winding array and the stator are vectorially superimposed at the air gap; The dual-channel inverter includes a main power channel for driving the stator winding and an excitation channel for supplying power to the rotor excitation winding through brushes and slip rings; The sensing network includes a current detection unit, a voltage detection unit, an encoder, a fiber grating sensor, and a magnetoresistive sensor. The current detection unit is used to detect the three-phase current output by the inverter, the voltage detection unit is used to detect the DC bus voltage, the encoder is used to detect the position and speed of the rotor, the fiber grating sensor is embedded in the permanent magnet array to detect the temperature of the magnetic steel, and the magnetoresistive sensor is arranged at the air gap to detect the synthetic magnetic field vector.

2. The permanent magnet synchronous drive assembly with speed change function according to claim 1, characterized in that: The reducer is a two-stage planetary reducer, the first-stage planetary transmission structure of the reducer is connected to the hybrid excitation motor, and the second-stage planetary transmission structure of the reducer is connected to the load.

3. The permanent magnet synchronous drive assembly with speed change function according to claim 1, characterized in that: The isolation layer is wound into a ring shape using nanocrystalline ribbons and is continuously wound along the circumference of the ring in a spiral involute trajectory. Each turn of the ribbon is offset relative to the previous turn, so that multiple turns of the ribbon are superimposed in a stepped offset manner.

4. The permanent magnet synchronous drive assembly with speed change function according to claim 3 is characterized in that: After the strip is wound for every 5 layers, a magnesium oxide insulation layer is sprayed to form an insulation barrier in a vertical axial direction.

5. The permanent magnet synchronous drive assembly with speed change function according to claim 1, characterized in that: The magnetic steel is arranged in sections along the axial direction of the rotor.

6. The permanent magnet synchronous drive assembly with speed change function according to claim 1, characterized in that: Non-magnetic conductive ribs are provided between adjacent N-pole magnetic steels and S-pole magnetic steels to limit circumferential magnetic leakage.

7. The permanent magnet synchronous drive assembly with speed change function according to claim 1, characterized in that: The controller configures the following dynamic control strategy: Through the EKF algorithm, the remanent magnetism of the permanent magnet array is estimated online based on the input three-phase current, DC bus voltage, rotor position, rotor speed, and magnetic steel temperature, and the current remanent magnetism and remanent magnetism attenuation are output; Dynamically adjust the electric excitation current output by the excitation channel according to the magnetic steel temperature, current residual magnetism, synthetic magnetic field vector, residual magnetism attenuation, and load demand; Wherein, when the temperature of the magnetic steel is greater than the temperature safety value, the reverse excitation current is started to weaken the synthetic magnetic field strength, and the amplitude of the excitation current is set according to the critical demagnetization magnetic field strength; When the demagnetization magnetic field intensity is greater than the critical demagnetization magnetic field intensity, the reverse excitation current is increased until the demagnetization magnetic field intensity is less than the critical demagnetization magnetic field intensity; When the temperature of the magnetic steel is lower than the temperature safety value and the demagnetization magnetic field strength is lower than the critical demagnetization magnetic field strength, the reverse excitation current is turned off; When residual magnetism decays or load demand increases, the forward excitation current is increased to enhance the synthetic magnetic field strength; The critical demagnetization magnetic field strength is calculated based on the real-time magnetic steel temperature, and the demagnetization magnetic field strength is calculated based on the current residual magnetism and the synthetic magnetic field vector.

8. The permanent magnet synchronous drive assembly with speed change function according to claim 7, characterized in that: The priority of using the demagnetization magnetic field intensity as an execution condition is higher than the priority of using the magnetic steel temperature as an execution condition, and the priority of using the magnetic steel temperature as an execution condition is higher than the priority of using others as execution conditions.

9. The permanent magnet synchronous drive assembly with speed change function according to claim 2, characterized in that: The reducer includes a housing, the first-stage planetary transmission structure and the second-stage planetary transmission structure are built in the housing, the first-stage planetary transmission structure includes a first sun gear, a first planetary wheel, a first planetary carrier, and a first inner gear ring; the first sun gear is connected to the hybrid excitation motor, the first inner gear ring is fixed to the housing, and the first planetary wheel is mounted on the first planetary carrier and is located between the first sun gear and the first inner gear ring; The second-stage planetary transmission structure includes a second sun gear, a second planetary wheel, a second planet carrier and a second inner ring gear; the second sun gear is connected to the first planet carrier, the second inner ring gear is fixed to the housing, the second planetary wheel is mounted on the second planet carrier and is located between the second sun gear and the second inner ring gear, and the second planet carrier is used to connect the load.

10. The permanent magnet synchronous drive assembly with speed change function according to claim 9, characterized in that: The number of the first planetary gears is set to four, and the number of the second planetary gears is set to three.

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