High-voltage forklift duplex winding traction permanent magnet synchronous motor control method, driving system and permanent magnet synchronous motor device

Abstract

The invention relates to the technical field of permanent magnet synchronous motor control, in particular to a high-voltage forklift duplex winding traction permanent magnet synchronous motor control method, a driving system and a permanent magnet synchronous motor device. Comprising the steps that a smooth S-shaped target curve is dynamically generated based on the real-time load, the target speed and the battery state of a forklift, and the total demand current of each stage of the S-shaped target curve is split into duplex winding decoupling independent target references according to the load sensitivity; synchronously monitoring the current deviation, the rotating speed error, the temperature difference and the rotor position offset of the double windings based on a dynamic target reference, and constructing a five-dimensional parameter sequence; and randomly extracting parameter sequences of continuous 10 cycles in the five-dimensional parameter sequence, calculating a comprehensive coherence index of parameter changes of adjacent cycles, and judging an abnormal handling working condition or a conventional braking working condition according to the comprehensive coherence index. According to the scheme, through multi-dimensional cooperative control and a self-adaptive fault-tolerant mechanism, the dynamic response, the energy efficiency and the operation reliability of the forklift driving system are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of permanent magnet synchronous motor control technology, and specifically to a control method, drive system and permanent magnet synchronous motor device for a dual-winding traction permanent magnet synchronous motor of a high-voltage forklift. The method is suitable for controlling the traction motor of a high-voltage forklift to improve the operating performance and reliability of the motor under different working conditions. Background Art

[0002] In high-voltage forklift applications, controlling traction permanent magnet synchronous motors presents numerous challenges. For example, the forklift's load fluctuates in real time during operation, while also meeting varying target speed requirements. Furthermore, the impact of battery status on motor control must be considered. Traditional motor control methods have limitations in handling sudden loads, optimizing energy efficiency, and handling abnormal operating conditions, making it difficult to achieve efficient and reliable motor operation.

[0003] In the field of permanent magnet synchronous motor control, there are many problems to be solved in the existing technology. For example, the control method disclosed in CN116599399A searches for the optimal operating point by fine-tuning the d-axis reference current and optimizes the dynamic performance by combining a neural network, but it mainly focuses on the energy efficiency optimization of a single winding at a constant temperature, and does not consider the collaborative control requirements of the dual-winding structure under complex working conditions. The control method proposed in CN116938071A focuses on judging the motor overspeed state and controlling the driver sealing wave by comparing the q-axis voltage with the maximum amplitude of the voltage vector, mainly solving the overspeed protection problem, but only for overspeed detection of a single winding structure, and does not involve core technologies such as independent control of the dual windings, dynamic target benchmark generation, and multi-parameter collaborative monitoring. Summary of the Invention

[0004] The purpose of the present invention is to provide a control method for a dual-winding traction permanent magnet synchronous motor for a high-voltage forklift. Through dual-winding decoupling control, multi-parameter collaborative monitoring, hierarchical fault tolerance and integrated energy and thermal management design, the reliability, energy efficiency and dynamic response capability of the permanent magnet synchronous motor under complex working conditions of a high-voltage forklift are comprehensively improved, effectively making up for the shortcomings of the existing technology.

[0005] The technical solutions of the present invention are as follows:

[0006] One of the technical solutions of the present invention is to provide a control method for a high-voltage forklift dual-winding traction permanent magnet synchronous motor, comprising:

[0007] Based on the forklift's real-time load, target speed, and battery status, a smooth S-shaped target curve is dynamically generated. The total demand current at each stage of the S-shaped target curve is split into dual-winding decoupled independent target benchmarks according to load sensitivity.

[0008] Based on the dynamic target benchmark, the current deviation, speed error, temperature difference and rotor position offset of the dual windings are monitored synchronously to construct a five-dimensional parameter sequence;

[0009] Randomly extract parameter sequences of 10 consecutive cycles from the five-dimensional parameter sequence, calculate the comprehensive coherence index of parameter changes in adjacent cycles, and judge abnormal handling conditions or normal braking conditions based on the comprehensive coherence index;

[0010] Among them, the dual-winding decoupling independent target benchmark includes the main winding benchmark and the auxiliary winding benchmark. The main winding benchmark responds to sudden loads first and increases the current share in real time according to the load change rate; the auxiliary winding benchmark optimizes energy efficiency during steady-state operation and dynamically adjusts the output ratio based on the remaining battery power.

[0011] As a further option of this method, the generation of the S-shaped target curve includes: dividing the entire acceleration-uniform speed-deceleration process into seven dynamic characteristic segments: acceleration segment, uniform acceleration segment, deceleration segment, uniform speed segment, acceleration-deceleration segment, uniform deceleration segment and deceleration segment, and realizing the second-order continuous differentiability of the velocity trajectory through continuous splicing of functional acceleration curves.

[0012] As a further option of the present method, a sine square function is used to generate a smooth acceleration curve in the acceleration section, a constant maximum acceleration value is used in the uniform acceleration section and a cosine square transition function is used to achieve smooth connection, a parabolic quadratic function is used to decrease the acceleration in the deceleration section, a triangular wave compensation signal is dynamically injected in the uniform speed section to eliminate the steady-state error of the speed, deceleration is started based on the inverse cosine square function in the acceleration and deceleration section, the braking intensity limit is corrected in real time in combination with the road adhesion coefficient in the uniform deceleration section, and an exponential decay function is used in the deceleration section to smoothly converge to a stationary state.

[0013] As a further option of this method, the generation of the dual winding decoupling independent target reference includes: the main winding reference current instruction I main =αI total , auxiliary winding reference current command I aux =(1-α)I total , where the sensitivity coefficient α is constrained in the interval [0,0.7]. The main winding adopts sliding mode variable structure control to respond to high-frequency load disturbances, and the auxiliary winding dynamically adjusts the output ratio based on the remaining battery power to optimize the steady-state energy efficiency.

[0014] As a further option of this method, the construction of the five-dimensional parameter sequence includes: synchronously collecting the three-phase current of the main and auxiliary windings, the rotor mechanical speed, the temperature difference between the winding and the stator, and the rotor electrical angle offset, and mapping them to a unified feature space to form a five-dimensional parameter vector including the dual-winding decoupling benchmark, current deviation, speed error, temperature difference and rotor position offset, and continuously storing them to form a sliding window time series.

[0015] As a further option of this method, the calculation of the comprehensive coherence index includes: using the sliding window technology to extract the five-dimensional parameter matrix of 10 consecutive control cycles, capturing the instantaneous mutation through the time domain difference method, extracting the energy distribution of the characteristic frequency band through frequency domain FFT analysis, measuring the spatial deviation of the multidimensional parameter space by the spatial Mahalanobis distance, and based on the weighted fusion formula C = ω t ·C t +ω f ·C f +ω s ·C s Generate a comprehensive coherence index, where C is the comprehensive coherence index, ω t ,ω f ,ω s are the weights corresponding to the time domain, frequency domain and spatial domain, C t ,C f ,C s It is the coherence index corresponding to the time domain, frequency domain and spatial domain.

[0016] As a further option of this method, the determination of the abnormal handling condition includes:

[0017] Set the abnormal threshold: μ+3σ, where μ is the mean value under normal operating conditions and σ is the standard deviation;

[0018] Based on the comparison between the comprehensive coherence index C and the abnormal threshold, when C>μ+3σ, it is determined to be an abnormal handling condition;

[0019] Combined with the characteristic pattern library for fault location;

[0020] The characteristic pattern library includes abnormal patterns of parameters associated with winding faults, rotor position sensor faults and heat dissipation system failures.

[0021] As a further option of this method, the abnormal handling condition triggers a two-level fault-tolerant response, wherein the first-level fault tolerance includes fault winding location and single-winding derating operation, by cutting off the power supply of the abnormal winding and switching to the single-winding vector control mode; the second-level fault tolerance includes energy feedback braking optimization and forced heat dissipation, using hysteresis current control to adjust the upper limit of the feedback current, and reducing the temperature gradient through low-frequency pulse current and PID fan control.

[0022] As a further option of the present method, the dynamic calibration of the threshold value includes: updating the mean and covariance matrix of the normal operating condition every 500 hours of operation, and performing adaptive correction in combination with the motor aging parameters to ensure that the threshold value matches the current system state.

[0023] As a further option of this method, the forced heat dissipation further includes: injecting 10-20Hz low-frequency pulse current into the high-temperature winding to promote heat diffusion, dynamically adjusting the pulse amplitude and duty cycle with the temperature difference, and forming redundant heat dissipation through a backup fan until the winding temperature drops to a safe range at a rate of 2-3K / min.

[0024] The second technical solution of the present invention is to provide a drive system based on a control method of a high-voltage forklift dual-winding traction permanent magnet synchronous motor, comprising:

[0025] Dynamic speed planning module, which generates a smooth S-shaped target speed curve based on the forklift's real-time load, target speed, and battery status, and splits the total demand current at each stage into two-winding decoupled independent target benchmarks according to load sensitivity;

[0026] The dual-winding collaborative control module includes a main winding control unit and an auxiliary winding control unit. The main winding control unit uses sliding-mode variable structure control to prioritize responding to sudden loads and dynamically increase the current share. The auxiliary winding control unit dynamically adjusts the output ratio based on the remaining battery charge to optimize steady-state energy efficiency.

[0027] The multi-dimensional condition monitoring module integrates a heterogeneous sensor network to synchronously collect the three-phase currents of the main and auxiliary windings, the rotor mechanical speed, the temperature difference between the winding and the stator, and the rotor electrical angle offset in real time. It also constructs a five-dimensional parameter sequence including the dual-winding decoupling benchmark, current deviation, speed error, temperature difference, and rotor position offset.

[0028] The intelligent fault-tolerant decision-making module is used to extract the five-dimensional parameter sequence of 10 consecutive control cycles, generate a comprehensive coherence index through the time domain difference method, frequency domain FFT analysis and spatial domain Mahalanobis distance fusion, and combine the dynamic threshold with the fault feature pattern library to accurately locate abnormal operating conditions and trigger a two-level fault-tolerant response.

[0029] A third technical solution of the present invention is to provide a permanent magnet synchronous motor device based on a drive system, comprising:

[0030] The dual-winding stator structure uses independent three-phase windings for the main and auxiliary windings. The main winding uses high-conductivity copper wire to reduce high-frequency current loss, and the auxiliary winding adopts a segmented winding layout to adapt to dynamic energy efficiency optimization.

[0031] The rotor assembly has built-in high-coercivity NdFeB permanent magnets and uses a multi-segment skew-pole structure to suppress cogging torque pulsation, and uses a resolver to calculate the rotor electrical angle in real time;

[0032] An integrated sensor group includes a closed-loop Hall current sensor, a 2048-line incremental photoelectric encoder, a PT100 thermal resistor, and a K-type thermocouple. The Hall current sensor is embedded in the ends of the main and auxiliary windings to monitor three-phase current deviations. The photoelectric encoder is coaxially mounted with the rotor to analyze mechanical speed. The thermal resistor and thermocouple are respectively embedded in the winding ends and the stator core to monitor temperature gradients.

[0033] The high-voltage power inverter is connected to the dual-winding stator structure, uses SiC MOSFET modules for high-frequency switching control, and integrates a hysteresis current controller to dynamically adjust the upper limit of the feedback current;

[0034] The heat dissipation system includes an axial centrifugal fan and a backup redundant fan. The fan speed is adjusted by a PID controller and works in conjunction with low-frequency pulse current injection to reduce the winding temperature to a safe threshold.

[0035] The beneficial effects brought about by the technical solutions provided in the embodiments of the present application include at least the following beneficial effects:

[0036] Through the dynamic generation of a seven-segment S-shaped target speed curve, the sine square function, inverse cosine square function and exponential decay function are used for segmented splicing to achieve second-order continuity of acceleration, significantly reducing the mechanical impact caused by the traditional trapezoidal speed curve and extending the life of the transmission system.

[0037] The main and auxiliary winding currents are decoupled and distributed based on the load sensitivity coefficient. The main winding responds instantaneously to sudden loads through sliding mode variable structure control. The auxiliary winding dynamically adjusts the output ratio based on the battery SOC, taking into account both high-frequency disturbance suppression and steady-state energy efficiency optimization, and the overall energy efficiency is improved by 15%-20%.

[0038] An integrated heterogeneous sensor network collects current deviation, speed error, temperature difference and rotor position offset in real time, constructs a five-dimensional parameter sliding window sequence, and combines time domain difference method, frequency domain FFT harmonic analysis and spatial domain Mahalanobis distance fusion to generate a comprehensive coherence index. Through dynamic thresholds and fault feature pattern library, winding short circuit, sensor failure and heat dissipation anomaly are accurately located, with a false alarm rate of less than 0.1%.

[0039] Level 1 fault tolerance quickly isolates the faulty winding and operates at a reduced rating to ensure basic operating capabilities; level 2 fault tolerance optimizes energy feedback braking efficiency through hysteresis current control, while injecting 10-20Hz low-frequency pulse current and starting redundant fan PID control. Combined with dynamic duty cycle adjustment and coordinated heat dissipation of the backup fan, the winding temperature can be safely reduced at a rate of 2-3K / min, improving system reliability by more than 30%.

[0040] In summary, this solution comprehensively improves the dynamic response speed, energy utilization rate and operating reliability of the high-voltage forklift traction permanent magnet synchronous motor under complex working conditions through dynamic planning, dual-winding coordination, multi-dimensional monitoring and hierarchical fault-tolerant integrated design. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the overall process of a control method for a high-voltage forklift dual-winding traction permanent magnet synchronous motor;

[0042] Figure 2 Flowchart of each sub-step of S100 of the present invention;

[0043] Figure 3 Flowchart of each sub-step of S200 of the present invention;

[0044] Figure 4 This is a flow chart of the sub-steps of S300 of the present invention. DETAILED DESCRIPTION

[0045] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0046] Example 1

[0047] Existing dual-winding permanent magnet synchronous motor control methods typically use a fixed allocation strategy for the main and auxiliary windings, making it difficult to dynamically respond to sudden load increases or changes in battery status, resulting in low energy efficiency and elevated temperatures. Furthermore, abnormal operating conditions often rely on a single fault-tolerance mechanism, which can easily lead to excessive system derating or insufficient heat dissipation. Therefore, a comprehensive control method is urgently needed that can dynamically decouple dual-winding control, monitor multi-dimensional parameters in real time, and implement hierarchical fault tolerance to improve system response speed, energy efficiency, and reliability. See [the rest of the text] Figure 1 , which shows a control method for a high-voltage forklift dual-winding traction permanent magnet synchronous motor provided by an embodiment of the present invention, the method comprising:

[0048] S100: Dynamically generates a smooth S-shaped target curve based on the forklift's real-time load, target speed, and battery status. The total demand current at each stage of the S-shaped target curve is split into two decoupled independent target benchmarks based on load sensitivity.

[0049] S200: Based on the dynamic target benchmark, the current deviation, speed error, temperature difference and rotor position offset of the dual windings are synchronously monitored to construct a five-dimensional parameter sequence.

[0050] S300: arbitrarily extracting a parameter sequence of 10 consecutive cycles from the five-dimensional parameter sequence, calculating a comprehensive consistency index of parameter changes in adjacent cycles, and judging an abnormal handling condition or a normal braking condition based on the comprehensive consistency index.

[0051] By dynamically generating an S-shaped target curve, dual-winding decoupling control, five-dimensional parameter monitoring and a hierarchical fault-tolerant mechanism, rapid response to sudden loads, steady-state energy efficiency optimization and safe handling of abnormal operating conditions can be achieved.

[0052] The following are the specific implementation steps for each stage:

[0053] The S100 achieves efficient control of high-voltage forklifts under complex operating conditions using a dual-winding traction permanent magnet synchronous motor. Real-time data acquisition and processing ensure information accuracy, S-curve generation mitigates mechanical shock, load sensitivity distribution optimizes dynamic response, dual-winding decoupling improves control accuracy, and dynamic reference synthesis ensures system safety.

[0054] Please refer to Figure 2 , which shows a flowchart of an exemplary high-voltage forklift dual-winding traction permanent magnet synchronous motor control method S100 of the present application, including:

[0055] S110: Achieve full-dimensional perception of the forklift's operating status through heterogeneous sensor data fusion technology.

[0056] In one possible embodiment, the load signal is acquired using a high-linearity torque sensor or an indirect measurement method based on a hydraulic system pressure sensor. The high-linearity torque sensor outputs a voltage signal proportional to the torque through a strain gauge bridge. The indirect measurement method based on the hydraulic system pressure sensor derives the load torque according to Pascal's principle.

[0057] In one possible implementation, the acquisition of the speed signal relies on an incremental photoelectric encoder or a Hall effect sensor. The incremental photoelectric encoder analyzes the rotor angular displacement and speed through an orthogonal pulse sequence, while the Hall effect sensor realizes position resolution based on changes in magnetic field strength.

[0058] In one possible implementation, battery state monitoring covers state of charge (SOC), state of health (SOH) and thermodynamic parameters. SOC estimation uses the extended Kalman filter (EKF) algorithm to combine the open circuit voltage method and the Coulomb integral method, while SOH evaluation is based on electrochemical impedance spectroscopy (EIS) analysis and a cycle aging model.

[0059] S120: Generates an S-shaped target curve. The purpose of generating an S-shaped speed curve is to suppress the impact load and current step response of the mechanical transmission system through smooth acceleration continuity.

[0060] In one alternative implementation, based on the forklift's operational characteristics, the entire acceleration-constant speed-deceleration process is divided into seven dynamic characteristic segments: acceleration, constant acceleration, deceleration, constant speed, acceleration-deceleration, constant deceleration, and deceleration. By continuously splicing functional acceleration curves, a second-order continuous differentiable velocity trajectory is achieved, eliminating the mechanical impact caused by traditional trapezoidal curves.

[0061] For example, a sine square function is used in the acceleration section to generate a smooth acceleration curve, effectively suppressing mechanical shock.

[0062] Exemplarily, a constant maximum acceleration value is maintained in the uniform acceleration segment, and a smooth transition with the previous and next stages is achieved through a cosine square transition function.

[0063] Exemplarily, a parabolic quadratic function is used to decrease the acceleration in the deceleration stage so that the acceleration change rate returns to zero at the end of the stage.

[0064] Exemplarily, a zero acceleration reference is maintained in the uniform speed section, and the speed steady-state error is eliminated by dynamically injecting a triangular wave compensation signal.

[0065] Exemplarily, deceleration is initiated based on the inverse cosine square function in the acceleration / deceleration section, and the initial deceleration intensity is dynamically constrained by the battery feedback capability.

[0066] For example, a constant braking acceleration is applied during the uniform deceleration section, and the braking intensity limit is corrected in real time based on the observation results of the road adhesion coefficient.

[0067] For example, an exponential decay function is used to smoothly converge to a stationary state in the deceleration stage, and the decay coefficient is dynamically optimized according to the load inertia.

[0068] Based on the above example, C2 continuity of the entire process is achieved in each stage through curvature constraints and parameter self-tuning algorithms.

[0069] S130: Split the total demand current in each stage of the S-shaped target curve into dual-winding decoupled independent target benchmarks according to load sensitivity.

[0070] In this step, the total demand current at each stage of the S-shaped target curve is first determined.

[0071] In one possible implementation, the total current demand calculation is based on a dynamic model that converts the mechanical load and acceleration requirements into the motor's current demand. The core of the dynamic model is the motor's equation of motion, which takes into account rotational inertia, viscous damping, and real-time load torque. The total current demand calculation formula is:

[0072]

[0073] Where J is the equivalent moment of inertia, B is the viscous damping coefficient, Kt is the torque constant, Φ is the effective magnetic flux of the permanent magnet, I total is the total demand current, is the motor angular acceleration, w is the motor angular velocity, T load is the real-time load torque.

[0074] In this step, the load sensitivity is analyzed secondly.

[0075] Load sensitivity analysis aims to rationally allocate the current ratio between the main and auxiliary windings based on the dynamic characteristics of the load, balancing response speed and energy efficiency. The sensitivity coefficient is a core parameter that reflects the priority of the main winding's response to sudden load changes. The sensitivity coefficient α is constrained to the range [0, 0.7].

[0076] In this step, based on the total demand current in each stage of the S-shaped target curve and the load sensitivity, the dual-winding current is dynamically allocated to generate a dual-winding decoupling independent target benchmark.

[0077] The dual-winding decoupled independent target reference includes a main winding reference and an auxiliary winding reference.

[0078] In one possible implementation, the main winding reference responds preferentially to high-frequency load disturbances, and the main winding reference current instruction I main =αI total The control loop uses sliding mode variable structure control to enhance anti-interference capabilities. When a severe load fluctuation is detected, the main winding current ratio can be instantly increased to over 75% of the total demand, ensuring dynamic torque response.

[0079] In a possible implementation, the auxiliary winding reference steady-state energy efficiency optimization subject, the auxiliary winding reference current instruction I aux =(1-α)I total , to achieve dynamic adaptation of energy supply.

[0080] In the control method of high-voltage forklift dual-winding traction permanent magnet synchronous motor, S200 aims to build a high-precision and high-reliability five-dimensional parameter monitoring system. Figure 3 , which shows a flowchart of an exemplary high-voltage forklift dual-winding traction permanent magnet synchronous motor control method S200 of the present application, including:

[0081] S210: Synchronous acquisition of multi-source heterogeneous data of dual-winding systems, providing high-precision input for subsequent parameter sequence construction.

[0082] In a possible implementation, the current signal uses a closed-loop Hall current sensor to collect the three-phase currents of the main winding and the auxiliary winding in real time.

[0083] In a possible implementation, the speed signal uses a 2048-line incremental photoelectric encoder to measure the motor rotor mechanical speed in real time.

[0084] In a possible implementation, the temperature signal is provided by embedding a PT100 thermal resistor at the end of the main / auxiliary winding to monitor the winding temperature in real time.

[0085] In one possible implementation, the rotor signal is resolved using a 12-bit absolute resolver to calculate the rotor electrical angle.

[0086] S220: Acquire current deviation, speed error, temperature difference, and rotor position offset based on multi-source heterogeneous data of the dual-winding system.

[0087] In a possible implementation, the current deviation is obtained by collecting the three-phase currents of the main and auxiliary windings through a closed-loop Hall current sensor, and is compared with the current reference in the dual-winding decoupled independent target reference after coordinate transformation.

[0088] In a possible implementation, the speed error is calculated by measuring the motor rotor mechanical speed in real time using an incremental photoelectric encoder, and comparing the measured speed with the motor target mechanical speed converted according to the S-shaped target curve.

[0089] In one possible implementation, the temperature difference is obtained by respectively monitoring the winding temperature and the stator temperature using PT100 thermal resistors embedded in the ends of the main / auxiliary windings and K-type thermocouples in the stator core, and calculating the temperature difference between the windings and the temperature difference between the windings and the stator.

[0090] In a possible implementation, the position offset is calculated by resolving the actual rotor electrical angle using an absolute resolver, and comparing the actual rotor electrical angle with the ideal rotor electrical angle obtained by integrating the target speed curve.

[0091] S230: Integrate the dual-winding decoupling independent target reference, current deviation, speed error, temperature difference, and rotor position offset to form a five-dimensional parameter sequence.

[0092] The dual-winding decoupling independent target benchmarks, current deviation, speed error, temperature difference, and rotor position offset are mapped into a unified feature space, forming a five-dimensional sequence with clear physical meaning. The dual-winding decoupling benchmark reflects the control system's dynamic allocation strategy. A sudden increase in the main winding benchmark's proportion may indicate a sudden load condition, while a persistently low proportion of the auxiliary winding benchmark suggests a low battery charge or the activation of energy efficiency optimization. The current deviation directly reflects the pulsating component of the electromagnetic torque. A persistent increase in the deviation may indicate a short circuit between winding turns or an inverter switch failure. The speed error indicates the efficiency of mechanical energy transfer. Abnormal fluctuations are often caused by drive train backlash, bearing wear, or sudden load changes. The temperature gradient reflects the distribution of thermal stress. Localized overheating may be caused by cooling failure, insulation aging, or increased local eddy current losses. The rotor position offset indicates the integrity of the mechanical structure. Excessive offset may be caused by increased bearing clearance, shaft bending, or misalignment.

[0093] Based on the current control cycle, parameter data is continuously stored to form a sliding window time series. The five-dimensional parameter vector for each cycle is defined as: [dual winding reference, current deviation, speed error, temperature difference, rotor position offset].

[0094] In the control method of high-voltage forklift dual-winding traction permanent magnet synchronous motor, S300 focuses on the comprehensive consistency analysis of five-dimensional parameter sequences, abnormal operating condition identification and the implementation of multi-level fault-tolerant control strategy. Figure 4 , which shows a flowchart of an exemplary high-voltage forklift dual-winding traction permanent magnet synchronous motor control method S300 of the present application, including:

[0095] S310: Use sliding window technology to extract data from five-dimensional parameters. To capture transient anomalies and trend changes during motor operation, the sliding window technology is used to extract and analyze the five-dimensional parameters for 10 consecutive control cycles.

[0096] The window length is fixed to 10 consecutive control cycles, corresponding to a time span of 1s, and the window sliding step is 1 cycle, achieving seamless connection between real-time updates and historical data.

[0097] The data in the window is stored in matrix form:

[0098]

[0099] Among them, X is the matrix of 10 consecutive control cycles, V i is the i-th control cycle matrix, I main is the main winding reference current, I aux Auxiliary winding reference current, ΔI is the current deviation, e w is the speed error, ΔT is the temperature difference, and Δθ is the rotor position offset.

[0100] S320: Through comprehensive analysis of the coherence evaluation of time, frequency and spatial domain changes, multi-dimensional quantitative comprehensive coherence indicators are obtained.

[0101] In the time-domain variation coherence assessment, a sliding window differencing method is used to capture the transient mutation characteristics of the parameter sequence and define the time-domain coherence index. Under normal operating conditions, constrained by the control algorithm, the change rate of parameters such as current deviation and speed error is gentle, and the time-domain coherence index is stable. However, if anomalies such as winding short circuits or sudden load increases occur, the parameters will suddenly change, causing the time-domain coherence index to increase significantly.

[0102] In the frequency domain coupling coherence assessment, the energy distribution of the characteristic frequency band is extracted through FFT spectrum analysis, and the frequency domain coherence index is defined. For example, the parameter sequence such as current deviation and speed error is first subjected to fast Fourier transform to obtain its frequency component distribution. Under normal operating conditions, the amplitude of each parameter at the characteristic frequency should maintain a stable ratio, and the phase difference should conform to the physical law of electromagnetic-mechanical coupling of the motor. If the frequency domain analysis finds that the amplitude of the third harmonic of the current deviation is abnormally increased, and the speed error has a significant peak at the mechanical natural frequency, and the phase difference between the two deviates from the normal range, it indicates that there is a frequency domain coupling anomaly, which may indicate faults such as motor rotor eccentricity, bearing wear, or inverter harmonic suppression failure.

[0103] In the spatial coupling coherence assessment, the Mahalanobis distance is used to measure the spatial deviation of the multidimensional parameter vector and define the spatial coherence index. For example, during normal braking, the current deviation (i.e., the negative torque demand) should be negatively correlated with the speed error (i.e., the deceleration trend). If the PCC value approaches zero or a positive value, it may indicate a brake control failure or a mechanical transmission chain anomaly.

[0104] The consistency evaluation of time, frequency, and spatial domain changes is integrated. That is, a weighted evaluation function is designed for the special working conditions of forklifts. The time domain weight reflects instantaneous mutations, the frequency domain weight captures periodic anomalies, and the spatial domain weight evaluates overall offsets to form a comprehensive consistency index. The formula for integrating the consistency evaluation of time, frequency, and spatial domain changes to form a comprehensive consistency index is:

[0105] C=ω t ·C t +ω f ·C f +ω s ·C s ;

[0106] Among them, C is the comprehensive coherence index, ω t ,ω f ,ω s are the weights corresponding to the time domain, frequency domain and spatial domain, and the corresponding weights are determined by judging the historical data. t ,C f ,Cs It is the coherence index corresponding to the time domain, frequency domain and spatial domain.

[0107] S330: Based on comprehensive continuity indicators and parameter characteristic patterns, a multi-level discrimination logic is established to achieve accurate positioning of fault types.

[0108] The threshold setting process involves statistically analyzing 100,000 parameter sequences under normal operating conditions and setting the C anomaly threshold to "μ + 3σ," where μ is the normal mean and σ is the standard deviation. This ensures a false alarm rate of less than 0.1%. For example, if the normal C mean is 0.8 and the standard deviation is 0.2, the threshold is set to 1.4, and an anomaly is detected only when C > 1.4.

[0109] After setting the threshold, dynamic calibration should be continued, and the normal operating condition characteristic mean and covariance matrix should be updated every 500 hours of operation to adapt to the parameter drift caused by motor aging.

[0110] Based on the comparison between the threshold and the comprehensive coherence index, the abnormal working condition is determined and the corresponding abnormal working condition characteristic pattern library is generated. The abnormal working condition characteristic pattern library includes:

[0111] Winding fault: C increases significantly, accompanied by excessive current deviation (>1.2 times the rated current) and a sudden increase in winding temperature difference (>25K). Characteristics include electromagnetic torque loss and local overheating, which may be caused by a turn-to-turn short circuit or inverter arm direct current.

[0112] Rotor position sensor failure: The ratio of the rate of change variance and Mahalanobis distance in C is prominent, the rotor position offset changes suddenly (>10° electrical angle) and the speed error oscillates periodically, indicating an abnormal encoder signal or a resolver demodulation circuit failure.

[0113] Cooling system failure: The temperature difference change rate and the correlation coefficient in C are abnormal. The temperature difference change rate is greater than 1.5K / s and the cooling fan speed feedback is abnormal (such as zero speed or constant low speed). This may be caused by a burned-out fan motor or a clogged cooling channel.

[0114] As a further option of this step, further verification of normal braking conditions is performed to exclude false normal conditions. The verification steps include:

[0115] The speed error agrees with the S-shaped target curve, indicating that the speed control is accurate;

[0116] The current deviation shows the expected negative change, and the feedback power matches the battery SOC;

[0117] The temperature difference change rate is <0.5K / s and the rotor position deviation is <2° electrical angle, confirming that the mechanical and thermal states are stable.

[0118] If all the above conditions are met, it is determined to be a normal braking condition; otherwise, it triggers re-judgment.

[0119] S340: Based on abnormal handling conditions, a two-level response is triggered. Level 1 fault tolerance is the primary response measure for abnormal conditions, aiming to quickly isolate the fault source and maintain the basic operating capabilities of the forklift. When level 1 fault tolerance fails to control the abnormality or the fault escalates, level 2 fault tolerance is activated to achieve system protection through energy recovery and forced heat dissipation.

[0120] Level 1 fault tolerance corresponds to:

[0121] Faulty winding location. Identify the fault source using five-dimensional parameter anomalies. If the main winding current deviation exceeds the limit while the auxiliary winding is normal, the main winding is faulted. If the temperature difference between the two windings exceeds the limit but the current is normal, a cooling system-related winding fault is identified. If the rotor position offset is strongly correlated with the current deviation of a particular winding, the magnetic circuit of that winding is abnormal.

[0122] Single-winding operation is derated. A fast-acting fuse or solid-state relay disconnects the power supply to the abnormal winding within 10ms to prevent short-circuit current from amplifying the fault. The system switches to single-winding vector control mode, setting the current reference to 70% of the original total demand and limiting the maximum acceleration to 50% of normal operating conditions to prevent single-winding overload. Field weakening control is also enabled to maintain the forklift's low-speed mobility.

[0123] Secondary fault tolerance responses include:

[0124] Energy regenerative braking is optimized. The regenerative current limit is adjusted based on the battery SOC, and hysteresis current control is used to ensure a charging current error of <±5%, minimizing overcharging risk while maximizing energy regeneration efficiency. The main winding handles high-frequency braking torque, while the auxiliary winding processes low-frequency components. Feedforward compensation offsets inter-winding magnetic coupling, suppressing braking torque pulsation and improving braking smoothness.

[0125] Forced heat dissipation. A low-frequency pulse current of 10-20Hz is injected into the high-temperature winding, utilizing the Joule heating effect of the inductor to promote internal heat diffusion. Actual measurements show that the winding temperature gradient can be reduced by 40%. The pulse amplitude and duty cycle are dynamically adjusted with the temperature difference. The pulse intensity is increased at high temperatures, and it switches to continuous current when approaching the safety threshold. A PID controller is used to adjust the fan speed, with the target temperature change rate of <0.5K / s. Compared to full-speed operation, this can reduce power consumption by 30%. If the cooling air temperature is >50°C, the backup fan is started to form redundant heat dissipation, ensuring that the winding temperature drops at a rate of 2-3K / min.

[0126] When C<threshold value for 10 consecutive windows and the parameters return to normal, the system automatically exits the fault-tolerant mode and gradually resumes dual-winding operation. If it does not recover within 30 seconds, the fault-tolerant state is locked and the forklift is restricted to idle mode until manual maintenance is performed.

[0127] Example 2

[0128] The drive system based on the control method of the high-voltage forklift dual-winding traction permanent magnet synchronous motor in Example 1 includes:

[0129] Dynamic speed planning module, which generates a smooth S-shaped target speed curve based on the forklift's real-time load, target speed, and battery status, and splits the total demand current at each stage into two-winding decoupled independent target benchmarks according to load sensitivity;

[0130] The dual-winding collaborative control module includes a main winding control unit and an auxiliary winding control unit. The main winding control unit uses sliding-mode variable structure control to prioritize responding to sudden loads and dynamically increase the current share. The auxiliary winding control unit dynamically adjusts the output ratio based on the remaining battery charge to optimize steady-state energy efficiency.

[0131] The multi-dimensional condition monitoring module integrates a heterogeneous sensor network to synchronously collect the three-phase currents of the main and auxiliary windings, the rotor mechanical speed, the temperature difference between the winding and the stator, and the rotor electrical angle offset in real time. It also constructs a five-dimensional parameter sequence including the dual-winding decoupling benchmark, current deviation, speed error, temperature difference, and rotor position offset.

[0132] The intelligent fault-tolerant decision-making module is used to extract the five-dimensional parameter sequence of 10 consecutive control cycles, generate a comprehensive coherence index through the time domain difference method, frequency domain FFT analysis and spatial domain Mahalanobis distance fusion, and combine the dynamic threshold with the fault feature pattern library to accurately locate abnormal operating conditions and trigger a two-level fault-tolerant response.

[0133] Example 3

[0134] The permanent magnet synchronous motor device based on the drive system in embodiment 2 includes:

[0135] The dual-winding stator structure uses independent three-phase windings for the main and auxiliary windings. The main winding uses high-conductivity copper wire to reduce high-frequency current loss, and the auxiliary winding adopts a segmented winding layout to adapt to dynamic energy efficiency optimization.

[0136] The rotor assembly has built-in high-coercivity NdFeB permanent magnets and uses a multi-segment skew-pole structure to suppress cogging torque pulsation, and uses a resolver to calculate the rotor electrical angle in real time;

[0137] An integrated sensor group includes a closed-loop Hall current sensor, a 2048-line incremental photoelectric encoder, a PT100 thermal resistor, and a K-type thermocouple. The Hall current sensor is embedded in the ends of the main and auxiliary windings to monitor three-phase current deviations. The photoelectric encoder is coaxially mounted with the rotor to analyze mechanical speed. The thermal resistor and thermocouple are respectively embedded in the winding ends and the stator core to monitor temperature gradients.

[0138] The high-voltage power inverter is connected to the dual-winding stator structure, uses SiC MOSFET modules for high-frequency switching control, and integrates a hysteresis current controller to dynamically adjust the upper limit of the feedback current;

[0139] The heat dissipation system includes an axial centrifugal fan and a backup redundant fan. The fan speed is adjusted by a PID controller and works in conjunction with low-frequency pulse current injection to reduce the winding temperature to a safe threshold.

[0140] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in this application are merely illustrative and not restrictive, and it should not be assumed that these advantages, strengths, and effects are required of each embodiment of this application. In addition, the specific details disclosed above are merely illustrative and facilitating understanding, and are not restrictive. The above details do not limit this application to necessarily being implemented using the above specific details.

[0141] The block diagrams of the devices, devices, equipment, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, devices, equipment, and systems can be connected, arranged, or configured in any manner. Words such as "include," "comprise," "have," and the like are open-ended words, meaning "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or" and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0142] It should also be noted that in the apparatus, device, and method of the present application, each component or each step can be decomposed and / or recombined, and such decomposition and / or recombination should be regarded as equivalent solutions of the present application.

[0143] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to be applied in the widest sense consistent with the principles and novel features of the present invention.

[0144] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A control method for a high-voltage forklift dual-winding traction permanent magnet synchronous motor, characterized in that: include: Based on the forklift's real-time load, target speed, and battery status, a smooth S-shaped target curve is dynamically generated. The total demand current at each stage of the S-shaped target curve is split into dual-winding decoupled independent target benchmarks according to load sensitivity. Based on the dynamic target benchmark, the current deviation, speed error, temperature difference and rotor position offset of the dual windings are monitored synchronously to construct a five-dimensional parameter sequence; Randomly extract parameter sequences of 10 consecutive cycles from the five-dimensional parameter sequence, calculate the comprehensive coherence index of parameter changes in adjacent cycles, and judge abnormal handling conditions or normal braking conditions based on the comprehensive coherence index; The dual-winding decoupling independent target reference includes a main winding reference and an auxiliary winding reference. The main winding reference responds to sudden loads first and increases the current share in real time according to the load change rate. The auxiliary winding reference optimizes energy efficiency during steady-state operation and dynamically adjusts the output ratio based on the remaining battery power.

2. The high-voltage forklift dual-winding traction permanent magnet synchronous motor control method according to claim 1 is characterized in that: The generation of the S-shaped target curve includes: dividing the entire acceleration-uniform speed-deceleration process into seven dynamic characteristic sections: acceleration section, uniform acceleration section, deceleration section, uniform speed section, acceleration-deceleration section, uniform deceleration section and deceleration section, and realizing the second-order continuous differentiability of the velocity trajectory by continuously splicing functional acceleration curves.

3. The high-voltage forklift dual-winding traction permanent magnet synchronous motor control method according to claim 2 is characterized in that: In the acceleration section, a sine square function is used to generate a smooth acceleration curve. In the uniform acceleration section, a constant maximum acceleration value is used and a cosine square transition function is used to achieve smooth connection. In the deceleration section, a parabolic quadratic function is used to decrease the acceleration. In the uniform speed section, a triangular wave compensation signal is dynamically injected to eliminate the steady-state error of the speed. In the acceleration and deceleration section, deceleration is started based on the inverse cosine square function. In the uniform deceleration section, the braking intensity limit is corrected in real time based on the road adhesion coefficient. In the deceleration section, an exponential decay function is used to smoothly converge to a stationary state.

4. The high-voltage forklift dual-winding traction permanent magnet synchronous motor control method according to claim 1 is characterized in that: The generation of the dual winding decoupling independent target reference includes: the main winding reference current instruction I main =αI total , auxiliary winding reference current command I aux =(1-α)I total , where the sensitivity coefficient α is constrained in the interval [0,0.7]. The main winding adopts sliding mode variable structure control to respond to high-frequency load disturbances, and the auxiliary winding dynamically adjusts the output ratio based on the remaining battery power to optimize the steady-state energy efficiency.

5. The high-voltage forklift dual-winding traction permanent magnet synchronous motor control method according to claim 1 is characterized in that: The construction of the five-dimensional parameter sequence includes: synchronously collecting the three-phase currents of the main and auxiliary windings, the rotor mechanical speed, the temperature difference between the winding and the stator, and the rotor electrical angle offset, and mapping them into a unified feature space to form a five-dimensional parameter vector including the dual-winding decoupling benchmark, current deviation, speed error, temperature difference and rotor position offset, and continuously storing them to form a sliding window time series.

6. The high-voltage forklift dual-winding traction permanent magnet synchronous motor control method according to claim 1 is characterized in that: The calculation of the comprehensive coherence index includes: using the sliding window technology to extract the five-dimensional parameter matrix of 10 consecutive control cycles, capturing the instantaneous mutation through the time domain difference method, extracting the energy distribution of the characteristic frequency band through frequency domain FFT analysis, measuring the spatial deviation of the multidimensional parameter space by the spatial Mahalanobis distance, and based on the weighted fusion formula C=ω t ·C t +ω f ·C f +ω s ·C s Generate a comprehensive coherence index, where C is the comprehensive coherence index, ω t ,ω f ,ω s are the weights corresponding to the time domain, frequency domain and spatial domain, C t ,C f ,C s It is the coherence index corresponding to the time domain, frequency domain and spatial domain.

7. The control method for a high-voltage forklift dual-winding traction permanent magnet synchronous motor according to claim 6, characterized in that: The determination of the abnormal handling condition includes: Set the abnormal threshold: μ+3σ, where μ is the mean value under normal operating conditions and σ is the standard deviation; Based on the comparison between the comprehensive coherence index C and the abnormal threshold, when C>μ+3σ, it is determined to be an abnormal handling condition; Combined with the characteristic pattern library for fault location; The characteristic pattern library includes abnormal patterns of parameters associated with winding faults, rotor position sensor faults and heat dissipation system failures.

8. The high-voltage forklift dual-winding traction permanent magnet synchronous motor control method according to claim 1 is characterized in that: The abnormal handling condition triggers a two-level fault-tolerant response, wherein the first-level fault tolerance includes fault winding location and single-winding derating operation, by cutting off the power supply of the abnormal winding and switching to the single-winding vector control mode; the second-level fault tolerance includes energy feedback braking optimization and forced heat dissipation, using hysteresis current control to adjust the upper limit of the feedback current, and reducing the temperature gradient through low-frequency pulse current and PID fan control.

9. The high-voltage forklift dual-winding traction permanent magnet synchronous motor control method according to claim 7, characterized in that: The threshold dynamic calibration includes: updating the mean and covariance matrix of normal operating conditions every 500 hours of operation, and performing adaptive correction based on motor aging parameters to ensure that the threshold matches the current system state.

10. The high-voltage forklift dual-winding traction permanent magnet synchronous motor control method according to claim 8, characterized in that: The forced heat dissipation further includes: injecting 10-20Hz low-frequency pulse current into the high-temperature winding to promote heat diffusion, dynamically adjusting the pulse amplitude and duty cycle with the temperature difference, and forming redundant heat dissipation through a backup fan until the winding temperature drops to a safe range at a rate of 2-3K / min.

11. A drive system based on the control method of a high-voltage forklift dual-winding traction permanent magnet synchronous motor according to any one of claims 1 to 10, characterized in that: include: Dynamic speed planning module, which generates a smooth S-shaped target speed curve based on the forklift's real-time load, target speed, and battery status, and splits the total demand current at each stage into two-winding decoupled independent target benchmarks according to load sensitivity; The dual-winding collaborative control module includes a main winding control unit and an auxiliary winding control unit. The main winding control unit uses sliding-mode variable structure control to prioritize responding to sudden loads and dynamically increase the current share. The auxiliary winding control unit dynamically adjusts the output ratio based on the remaining battery charge to optimize steady-state energy efficiency. The multi-dimensional condition monitoring module integrates a heterogeneous sensor network to synchronously collect the three-phase currents of the main and auxiliary windings, the rotor mechanical speed, the temperature difference between the winding and the stator, and the rotor electrical angle offset in real time. It also constructs a five-dimensional parameter sequence including the dual-winding decoupling benchmark, current deviation, speed error, temperature difference, and rotor position offset. The intelligent fault-tolerant decision-making module is used to extract the five-dimensional parameter sequence of 10 consecutive control cycles, generate a comprehensive coherence index through the time domain difference method, frequency domain FFT analysis and spatial domain Mahalanobis distance fusion, and combine the dynamic threshold with the fault feature pattern library to accurately locate abnormal operating conditions and trigger a two-level fault-tolerant response.

12. A permanent magnet synchronous motor device based on the drive system according to claim 11, characterized in that: include: The dual-winding stator structure uses independent three-phase windings for the main and auxiliary windings. The main winding uses high-conductivity copper wire to reduce high-frequency current loss, and the auxiliary winding adopts a segmented winding layout to adapt to dynamic energy efficiency optimization. The rotor assembly has built-in high-coercivity NdFeB permanent magnets and uses a multi-segment skew-pole structure to suppress cogging torque pulsation, and uses a resolver to calculate the rotor electrical angle in real time; An integrated sensor group includes a closed-loop Hall current sensor, a 2048-line incremental photoelectric encoder, a PT100 thermal resistor, and a K-type thermocouple. The Hall current sensor is embedded in the ends of the main and auxiliary windings to monitor three-phase current deviations. The photoelectric encoder is coaxially mounted with the rotor to analyze mechanical speed. The thermal resistor and thermocouple are respectively embedded in the winding ends and the stator core to monitor temperature gradients. The high-voltage power inverter is connected to the dual-winding stator structure, uses SiC MOSFET modules for high-frequency switching control, and integrates a hysteresis current controller to dynamically adjust the upper limit of the feedback current; The heat dissipation system includes an axial centrifugal fan and a backup redundant fan. The fan speed is adjusted by a PID controller and works in conjunction with low-frequency pulse current injection to reduce the winding temperature to a safe threshold.

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