A design method for improving torque and rotating speed of a current superimposed motor excitation magnet

Abstract

This invention relates to the field of multiphase motor magnetic field control technology, and proposes a design method for improving torque and speed by superimposing current to regulate motor excitation. It addresses issues such as the significant increase in stator armature demagnetizing current during high-speed field weakening operation, leading to a sharp rise in copper and iron losses and severe degradation of overall machine efficiency, as well as the reliance on rare-earth permanent magnet materials and the associated raw material supply risks. This invention eliminates the independent excitation winding, allowing the six-phase stator windings to simultaneously perform armature and excitation functions, shortening the winding end length, increasing stator slot utilization by 55%, reducing leakage flux and copper losses, and eliminating the need for rare-earth permanent magnets, thus lowering raw material costs and reducing supply chain risks.

Description

Technical Field

[0001] This invention relates to the field of multiphase motor magnetic field control technology, specifically a design method for improving torque and speed by superimposing current to adjust the excitation of a motor. Background Technology

[0002] Currently, commercial drive motors are mainly divided into four categories: permanent magnet synchronous motors, induction asynchronous motors, traditional independent electric excitation motors, and multiphase switched reluctance motors.

[0003] Permanent magnet synchronous motors rely on built-in permanent magnets to establish the main magnetic field, and the magnetic field strength cannot be actively and continuously adjusted. When the field is weakened at high speed, the demagnetizing current of the stator armature increases significantly, copper loss and iron loss rise sharply, and the overall efficiency of the machine is severely reduced. At the same time, it relies on rare earth permanent magnet materials, which poses risks to the supply of raw materials, irreversible demagnetization defects at high temperatures, limited space for increasing torque at low speed and heavy load, and narrow power speed regulation bandwidth.

[0004] Induction asynchronous motors have no permanent magnets and are reliable in operation, but they have low torque density and are larger and heavier for the same output torque. Stator and rotor iron losses are significant under high-speed conditions, resulting in low overall energy efficiency.

[0005] Traditional independent electric excitation motors have two sets of coils, the armature winding and the excitation winding, which are isolated from each other. The motor stator slot utilization rate is low, the end winding is long, and the leakage magnetic loss is large. The currents of the two sets of windings are coupled and constrained, and the magnetic field can only be adjusted in stages. It is impossible to continuously steplessly adjust the magnetic field, making it difficult to simultaneously meet the requirements of low speed, heavy load, high torque and ultra-wide high-speed operation.

[0006] Existing six-phase multiphase motor drive schemes only utilize multiphase winding shunt to reduce the current stress of single-circuit devices and only output pure AC armature current. They do not utilize multiphase windings to achieve DC excitation superposition and magnetic field adjustment functions. Magnetic field regulation and torque control are isolated from each other, and it is impossible to dynamically change the main magnetic flux through current superposition. The motor's full-range output performance has a significant bottleneck.

[0007] Therefore, current motors generally suffer from industry pain points such as redundant excitation structure, discrete and discontinuous magnetic flux adjustment, insufficient low-speed torque output, limited high-speed operation speed, and low winding material utilization. There is an urgent need to develop a new motor design and control scheme that does not require an independent excitation winding, relies on the superposition of AC and DC currents to achieve stepless dynamic magnetic adjustment, and simultaneously improves low-speed torque and maximum speed. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a design method for improving torque and speed by superimposing current to adjust the excitation of a motor. This method solves the problem that the stator armature demagnetizing current increases significantly during high-speed field weakening operation, leading to a sharp rise in copper and iron losses and a severe decrease in overall machine efficiency.

[0009] To achieve the above objectives, the present invention provides the following technical solution: A design method for improving torque and speed of a motor by superimposing current to adjust the excitation field, comprising the following steps: S1. Driver Topology Setup: A dual three-phase full-bridge inverter with a shared DC bus drives two sets of three-phase windings. The inverter outputs a superimposed AC and DC voltage to the six-phase windings. The winding current is decomposed into an AC armature component that generates rotating torque and a DC excitation component that regulates the main magnetic flux. The DC excitation components of the two sets of three-phase windings change the magnitude of the synthesized main magnetic flux through vector superposition, thereby achieving continuous stepless adjustment of the main magnetic flux. S2, Speed-range adaptive excitation control: Based on the real-time speed of the six-phase salient pole reluctance motor, three operating ranges are divided: low speed, medium speed, and high speed. In the low speed range, the DC excitation current is superimposed in the same direction to increase magnetization and improve output torque. In the high speed range, the DC excitation current is superimposed in the opposite direction to weaken magnetization and reduce the main magnetic flux and suppress back electromotive force to widen the upper limit of speed. S3, Current Reconfiguration and Closed-Loop Vector Control: Real-time phase currents of six-phase windings are collected and superimposed and reconstructed accordingly. The DC excitation component is filtered out to obtain the virtual three-phase composite current. Based on the virtual three-phase composite current, a dual closed-loop magnetic field-oriented vector control with an outer speed loop and an inner current loop is constructed to achieve decoupled control of excitation and torque components. S4. Fault-tolerant operation control: The system monitors the operating status of the windings and drive circuits in real time. When a single-phase or single-group three-phase winding fault is detected, the faulty circuit is cut off, the AC / DC current superposition ratio of the remaining normal windings is reconstructed, and the motor continues to operate with reduced capacity.

[0010] Preferably, in step S2, the six-phase salient pole reluctance motor includes a 12-slot stator and a 10-pole salient pole rotor. The rotor does not have permanent magnets or rotor windings. The stator is equipped with an integrated six-phase winding. The six-phase winding is divided into an electrically symmetrical first three-phase winding A, B, C and a second three-phase winding D, E, F. The stator winding is reused as an integrated armature and excitation winding, and no separate excitation winding is set up.

[0011] Preferably, the AC / DC superimposed voltage of the six-phase windings in step S1 satisfies the following set of equations: In the formula: This is a virtual three-phase AC voltage. This is the DC bias voltage, and the adjustable range of the DC bias voltage is... .

[0012] Preferably, the stator-side DC excitation current forms a 6-pole fixed magnetomotive force, and the 6-pole magnetomotive force is modulated by the 10-pole salient rotor magnetic permeability to generate a 4-pole continuously adjustable working main magnetic flux; the AC armature component generates a 4-pole rotating magnetic field, which couples with the modulated main magnetic flux to generate an electromagnetic torque to drive the rotor to run.

[0013] Preferably, the excitation control strategy for the three speed ranges in step S2 is as follows: Low speed and high torque range: motor speed (n≤3000r / min), increase DC bias voltage to +1V~+5V, the DC excitation components of the two sets of three-phase windings are superimposed in the same direction, increase the amplitude of the synthesized main magnetic flux, and simultaneously increase the amplitude of AC armature current to enhance electromagnetic torque output. Medium speed rated range: (3000r / min<n≤5000r / min), stabilize DC bias voltage to 0.5V~1V, maintain rated main magnetic flux, evenly distribute AC and DC current of the two sets of three-phase windings, and reduce winding conduction loss; High-speed field weakening range: When the motor speed is (n>5000r / min), the DC bias voltage is reduced to 0V to -5V. The reverse vector superposition of the DC excitation components of the two sets of three-phase windings cancels the main magnetic flux, suppresses the back electromotive force of the motor, and widens the maximum operating speed.

[0014] Preferably, the calculation formula for generating the virtual three-phase composite current through six-phase current reconstruction in step S4 is as follows: ; In the formula: (IA, IB, IC, ID, IE, IF) are the real-time phase currents of the six-phase windings, and (IU, IV, IW) are the virtual three-phase composite currents after filtering out the DC excitation component.

[0015] Preferably, the dual three-phase full-bridge inverters share a single DC bus, and the inverters are equipped with dual hardware and software protection mechanisms, including overcurrent protection for each phase, DC bus undervoltage protection, and power board over-temperature protection. The inverter's PWM switching frequency is not less than 20kHz, and the output dead-time control range is 200ns to 500ns.

[0016] Preferably, the fault tolerance control in step S4 specifically includes: the main control unit collects phase current and temperature signals to determine the fault location, cuts off the drive bridge arm corresponding to the faulty winding, recalculates the DC bias ratio and AC current amplitude of the remaining normal windings, and outputs the reconstructed PWM drive signal to maintain the motor's de-capacitated operation.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention eliminates the independent excitation winding, allowing the six-phase stator winding to simultaneously perform armature and excitation functions, shortening the winding end length, increasing stator slot utilization by 55%, reducing leakage flux and copper loss, and eliminating the need for rare earth permanent magnets, thereby reducing raw material costs and supply chain risks.

[0018] 2. This invention achieves continuous magnetic flux adjustment by relying on the superposition of DC excitation components of two sets of three-phase windings, breaking through the limitations of traditional excitation winding-type magnetic adjustment, and has fast magnetic field adjustment response speed and high control accuracy.

[0019] 3. This invention generates virtual three-phase signals through six-phase current reconstruction, which can be directly adapted to mature three-phase vector control algorithms, reducing the difficulty of controller development. At the same time, it integrates phase loss fault-tolerant operation function to improve equipment reliability. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a control block diagram of the dynamic flux adjustment of the present invention; Figure 2 This is a schematic diagram of the armature winding configuration of the present invention; Figure 3 This is a schematic diagram of the connection relationship in this invention; Figure 4 The figure shows the experimental data results of this invention. Detailed Implementation

[0021] The following will describe in detail the implementation of this application with reference to the accompanying drawings and embodiments, so that the implementation process of how this application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0022] Reference Figures 1-4 This embodiment proposes that... A design method for improving torque and speed of a motor by superimposing current to adjust the excitation field, comprising the following steps: S1. Driver Topology Setup: A dual three-phase full-bridge inverter with a shared DC bus drives two sets of three-phase windings. The inverter outputs a superimposed AC and DC voltage to the six-phase windings. The winding current is decomposed into an AC armature component that generates rotating torque and a DC excitation component that regulates the main magnetic flux. The DC excitation components of the two sets of three-phase windings change the magnitude of the synthesized main magnetic flux through vector superposition, thereby achieving continuous stepless adjustment of the main magnetic flux. S2, Speed-range adaptive excitation control: Based on the real-time speed of the six-phase salient pole reluctance motor, three operating ranges are divided: low speed, medium speed, and high speed. In the low speed range, the DC excitation current is superimposed in the same direction to increase magnetization and improve output torque. In the high speed range, the DC excitation current is superimposed in the opposite direction to weaken magnetization and reduce the main magnetic flux and suppress back electromotive force to widen the upper limit of speed. S3, Current Reconfiguration and Closed-Loop Vector Control: Real-time phase currents of the six-phase windings are acquired and superimposed / reconstructed accordingly. The DC excitation component is filtered out to obtain a virtual three-phase composite current. Using this virtual three-phase current as feedback, a dual-closed-loop PI vector control system with an outer speed loop and an inner current loop is employed. The current loop bandwidth is set to... By combining the rotor Hall position signal or encoder signal, field-oriented control is completed, thereby decoupling the excitation component from the torque component and ensuring that the current quickly tracks the command value.

[0023] S4. Fault-tolerant operation control: The system monitors the operating status of the windings and drive circuits in real time. When a single-phase or single-group three-phase winding fault is detected, the faulty circuit is cut off, the AC / DC current superposition ratio of the remaining normal windings is reconstructed, and the motor continues to operate with reduced capacity.

[0024] In step S2, the six-phase salient pole reluctance motor includes a 12-slot stator and a 10-pole salient pole rotor. The rotor does not have permanent magnets or rotor windings. The stator is equipped with an integrated six-phase winding. The six-phase winding is divided into an electrically symmetrical first three-phase winding A, B, C and a second three-phase winding D, E, F. The stator winding is reused as an integrated armature and excitation winding, and no separate excitation winding is set up.

[0025] In step S1, the AC / DC superimposed voltages of the six-phase windings satisfy the following set of equations:

[0026] In the formula: This represents a virtual three-phase AC voltage, corresponding to the armature torque current component. This is the DC bias voltage, corresponding to the excitation current component. The adjustable range of the DC bias voltage is... The magnitude and polarity of the DC bias voltage directly determine the magnitude and superposition direction of the DC excitation current. The DC excitation current on the stator side forms a 6-pole fixed magnetomotive force. After being modulated by the 10-pole salient rotor magnetic permeability, the 6-pole magnetomotive force generates a 4-pole continuously adjustable main magnetic flux. The AC armature component generates a 4-pole rotating magnetic field, which couples with the modulated main magnetic flux to generate electromagnetic torque to drive the rotor.

[0027] The excitation control strategy for the three speed ranges in step S2 is as follows: Low speed and high torque range: motor speed (n≤3000r / min), increase DC bias voltage to +1V~+5V, the DC excitation components of the two sets of three-phase windings are superimposed in the same direction, increase the amplitude of the synthesized main magnetic flux, and simultaneously increase the amplitude of AC armature current to enhance electromagnetic torque output.

[0028] Control logic: The voltage is increased to +1V to +5V. The DC excitation current is superimposed in the same direction to strengthen the main magnetic flux, and the amplitude of the six-phase AC armature current is increased synchronously. The vector modulation adopts a low-pulse algorithm to reduce torque fluctuation, thereby achieving a 15% to 47% increase in low-speed torque.

[0029] Medium speed rated range: (3000r / min<n≤5000r / min), stabilize DC bias voltage to 0.5V~1V, maintain rated main magnetic flux, evenly distribute AC and DC current of the two sets of three-phase windings, and reduce winding conduction loss.

[0030] Control logic: The voltage is stabilized between 0.5V and 1V, maintaining the rated main magnetic flux, and the AC and DC currents of the two groups of three-phase windings are evenly distributed to balance the winding heating and current stress, resulting in a stable overall efficiency of over 88%.

[0031] High-speed field weakening range: When the motor speed is (n>5000r / min), the DC bias voltage is reduced to 0V to -5V. The reverse vector superposition of the DC excitation components of the two sets of three-phase windings cancels the main magnetic flux, suppresses the back electromotive force of the motor, and widens the maximum operating speed.

[0032] Control logic: The voltage is reduced to 0V to -5V, and the DC excitation is superimposed in reverse to cancel the main magnetic flux. The armature current is appropriately reduced to avoid overload of power devices. The back electromotive force is collected in real time to dynamically correct the excitation ratio. The maximum stable speed can reach 15000r / min, and the power speed regulation bandwidth is 35 times.

[0033] The calculation formula for generating the virtual three-phase composite current through six-phase current reconstruction in step S4 is as follows: ; In the formula: (IA, IB, IC, ID, IE, IF) are the real-time phase currents of the six-phase windings, and (IU, IV, IW) are the virtual three-phase composite currents after filtering out the DC excitation component.

[0034] The drive unit adopts a dual three-phase full-bridge inverter, which shares a single DC bus. The continuous rated current of each phase winding is ≥10A (rms), and the short-time peak current is 30A (lasting 10s). The inverter is equipped with dual hardware and software protection mechanisms, including overcurrent protection for each phase, DC bus undervoltage protection, and power board overtemperature protection. The rated bus voltage is 14V, with a voltage fluctuation range of 12V to 16V. The inverter's PWM switching frequency is not less than 20kHz, and the output dead-time control range is 200ns to 500ns to suppress winding current ripple. The inverter contains 12 power MOSFETs, which drive the A, B, C and D, E, and F three-phase windings respectively. The inverter's hardware protection thresholds are: single overcurrent 35A, bus undervoltage 10V, and power board overtemperature 85℃.

[0035] The winding current consists of two independent components: an AC armature component and a DC excitation component. The AC armature component generates a rotating magnetic field, which determines the magnitude of the motor's output electromagnetic torque. The synchronous superposition of the AC components from the two sets of three-phase windings enhances the torque output capability. The DC excitation component establishes the motor's fundamental main magnetic field and is the core of flux regulation. By changing the polarity and amplitude of the DC bias voltage of the two sets of windings, the DC excitation vector can be superimposed in two modes: in the same direction and in opposite directions. In the same direction, the magnetomotive forces of the two sets of DC excitations are in phase, increasing the amplitude of the synthesized main magnetic flux and achieving magnetization. In opposite directions, the magnetomotive forces of the two sets of DC excitations cancel each other out, decreasing the amplitude of the synthesized main magnetic flux and achieving magnetization weakening. By continuously adjusting Vdc, stepless continuous adjustment of the main magnetic flux from maximum magnetization to deep magnetization weakening can be achieved.

[0036] The fault tolerance control in step S4 specifically includes: the main control unit collects the current of each phase, the temperature of the power board, and the bus voltage signal in real time, determines the fault type, and the fault types include single-phase winding open circuit, single-group three-phase drive bridge damage, and winding short circuit fault. After the fault is triggered, the drive signal of the fault circuit is immediately cut off, the DC bias voltage and AC current amplitude ratio of the remaining normal winding are recalculated, the current superposition logic is reconstructed, and the motor continues to run in a power reduction mode to avoid the whole machine shutdown failure.

[0037] When the motor of a new energy vehicle is running at a stable speed of 2000 r / min during low-speed start-up or hill climbing, which is in the low-speed, high-torque range, the main controller increases the DC bias voltage to +4V. The DC excitation currents of the two sets of three-phase windings are superimposed in the same direction, and the main magnetic flux reaches its maximum value. The peak value of the AC armature current is increased simultaneously. The output torque of the motor is 38% higher than that of a traditional switched reluctance motor of the same specification, which meets the power requirements for full-load hill climbing, and the torque ripple is controlled within 5%.

[0038] Under the constant speed and medium speed cruising conditions of the vehicle, the motor maintains a stable speed of 4000 r / min, which is within the medium speed rated range. The DC bias voltage is stable at 0.8V, maintaining the rated main magnetic flux. The current is evenly distributed between the two sets of three-phase windings, reducing the current stress of a single winding. The overall efficiency of the machine is 90.2%, and copper loss and iron loss are reduced to the minimum, extending the driving range.

[0039] When the vehicle is traveling at high speed, the motor has a stable speed of 12,000 r / min, which is in the high-speed field weakening range. The main controller adjusts the DC bias voltage to -3V, and the DC excitation components of the two windings are superimposed in opposite directions, which greatly weakens the main magnetic flux and suppresses the back electromotive force of the motor. The inverter shunts the current of the single power device, and the motor runs stably without overvoltage or overcurrent faults. The overall operating efficiency is 89.1%.

[0040] Working principle: When the system is powered on, the DC-DC module outputs a stable 14V DC bus voltage, the inverter enters standby mode, and the sensors collect real-time data on speed, phase current, bus voltage, power board temperature, and rotor position signals and upload them to the main controller.

[0041] The main controller determines the current operating range based on the rotor speed signal and calls the corresponding DC bias voltage and AC / DC current superposition control strategy.

[0042] The controller calculates the target output voltage of the six phases according to the voltage superposition equation, generates 12 PWM drive signals and sends them to the dual three-phase inverter. The AC and DC superposition voltages of each phase output are generated by superimposing the DC excitation vector to generate the target main magnetic flux, and the AC armature component generates a rotating magnetic field to drive the rotor to rotate.

[0043] Six current sensors collect real-time six-phase winding currents, calculate the virtual three-phase composite current according to the reconstruction formula, and send it to the speed and current dual closed-loop PI controller to dynamically correct the Vdc amplitude and armature current command, thus completing the closed-loop correction of magnetic flux, speed, and torque.

[0044] The main controller monitors fault signals in real time. If faults such as short circuit, open circuit, overheating of power devices, or undervoltage of the bus are detected, the drive signal of the fault circuit is immediately cut off, the excitation and current ratio of the remaining windings are reconstructed, the motor continues to run with reduced capacity, and the fault code is reported.

[0045] After the shutdown command is issued, the controller sequentially shuts down the inverter PWM output and cuts off the DC-DC power supply, thus powering down the entire unit.

[0046] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0047] 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 design method for improving torque and speed of a motor by superimposing current to adjust the excitation field, characterized in that, Includes the following steps: S1. Driver Topology Setup: A dual three-phase full-bridge inverter with a shared DC bus drives two sets of three-phase windings. The inverter outputs a superimposed AC and DC voltage to the six-phase windings. The winding current is decomposed into an AC armature component that generates rotating torque and a DC excitation component that regulates the main magnetic flux. The DC excitation components of the two sets of three-phase windings change the magnitude of the synthesized main magnetic flux through vector superposition, thereby achieving continuous stepless adjustment of the main magnetic flux. S2, Speed-range adaptive excitation control: Based on the real-time speed of the six-phase salient pole reluctance motor, three operating ranges are divided: low speed, medium speed, and high speed. In the low speed range, the DC excitation current is superimposed in the same direction to increase magnetization and improve output torque. In the high speed range, the DC excitation current is superimposed in the opposite direction to weaken magnetization and reduce the main magnetic flux and suppress back electromotive force to widen the upper limit of speed. S3, Current Reconfiguration and Closed-Loop Vector Control: Real-time phase currents of six-phase windings are collected and superimposed and reconstructed accordingly. The DC excitation component is filtered out to obtain the virtual three-phase composite current. Based on the virtual three-phase composite current, a dual closed-loop magnetic field-oriented vector control with an outer speed loop and an inner current loop is constructed to achieve decoupled control of excitation and torque components. S4. Fault-tolerant operation control: The system monitors the operating status of the windings and drive circuits in real time. When a single-phase or single-group three-phase winding fault is detected, the faulty circuit is cut off, the AC / DC current superposition ratio of the remaining normal windings is reconstructed, and the motor continues to operate with reduced capacity.

2. The design method for improving torque and speed of a motor by superimposing current excitation and adjusting the magnetic field according to claim 1, characterized in that, In step S2, the six-phase salient pole reluctance motor includes a 12-slot stator and a 10-pole salient pole rotor. The rotor does not have permanent magnets or rotor windings. The stator is equipped with an integrated six-phase winding. The six-phase winding is divided into an electrically symmetrical first three-phase winding A, B, C and a second three-phase winding D, E, F. The stator winding is reused as an integrated armature and excitation winding, and no separate excitation winding is set up.

3. The design method for improving torque and speed of a current-superimposed motor excitation and magnetic field adjustment according to claim 2, characterized in that, In step S1, the AC / DC superimposed voltages of the six-phase windings satisfy the following set of equations: In the formula: This is a virtual three-phase AC voltage. This is the DC bias voltage, and the adjustable range of the DC bias voltage is... .

4. The design method for improving torque and speed of a current-superimposed motor excitation and magnetic field adjustment according to claim 1, characterized in that, The stator-side DC excitation current forms a 6-pole fixed magnetomotive force. After the 6-pole magnetomotive force is modulated by the 10-pole salient rotor magnetic permeability, it generates a 4-pole continuously adjustable working main magnetic flux. The AC armature component generates a 4-pole rotating magnetic field, which couples with the modulated main magnetic flux to generate electromagnetic torque to drive the rotor.

5. The design method for improving torque and speed of a motor by superimposing current excitation and adjusting the magnetic field according to claim 1, characterized in that, The excitation control strategy for the three speed ranges in step S2 is as follows: Low speed and high torque range: motor speed (n≤3000r / min), increase DC bias voltage to +1V~+5V, the DC excitation components of the two sets of three-phase windings are superimposed in the same direction, increase the amplitude of the synthesized main magnetic flux, and simultaneously increase the amplitude of AC armature current to enhance electromagnetic torque output. Medium speed rated range: (3000r / min<n≤5000r / min), stabilize DC bias voltage to 0.5V~1V, maintain rated main magnetic flux, evenly distribute AC and DC current of the two sets of three-phase windings, and reduce winding conduction loss; High-speed field weakening range: When the motor speed is (n>5000r / min), the DC bias voltage is reduced to 0V to -5V. The reverse vector superposition of the DC excitation components of the two sets of three-phase windings cancels the main magnetic flux, suppresses the back electromotive force of the motor, and widens the maximum operating speed.

6. The design method for improving torque and speed of a current-superimposed motor excitation and magnetic field adjustment according to claim 1, characterized in that, The calculation formula for generating the virtual three-phase composite current through six-phase current reconstruction in step S4 is as follows: ； In the formula: (IA, IB, IC, ID, IE, IF) are the real-time phase currents of the six-phase windings, and (IU, IV, IW) are the virtual three-phase composite currents after filtering out the DC excitation component.

7. The design method for improving torque and speed of a current-superimposed motor excitation and magnetic field adjustment according to claim 1, characterized in that, The dual three-phase full-bridge inverters share a single DC bus. The inverters are equipped with dual hardware and software protection mechanisms, including overcurrent protection for each phase, DC bus undervoltage protection, and power board over-temperature protection. The inverters have a PWM switching frequency of no less than 20kHz and an output dead-time control range of 200ns to 500ns.

8. The design method for improving torque and speed of a current-superimposed motor excitation and magnetic field adjustment according to claim 1, characterized in that, The fault tolerance control in step S4 specifically includes: the main control unit collects phase current and temperature signals to determine the fault location, cuts off the drive bridge arm corresponding to the faulty winding, recalculates the DC bias ratio and AC current amplitude of the remaining normal windings, and outputs the reconstructed PWM drive signal to maintain the motor's de-capacitated operation.

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