A control method and system of a backpack type drive integrated permanent magnet synchronous motor

Abstract

The application relates to the technical field of motor control, in particular to a backpack type driving integrated permanent magnet synchronous motor control method and system, which comprises the following steps: an operating parameter detection step, which collects operating parameters reflecting the real-time working state of a motor and the state of a permanent magnet, and integrates and generates real-time state parameters; a magnet state analysis step, which is configured with a magnet demagnetization analysis strategy and is used for analyzing the demagnetization risk index of the permanent magnet under the real-time state parameters; a critical current analysis step, which is based on the demagnetization risk index and analyzes a preset current safety threshold dynamic adjustment model to generate a dynamic range safety current threshold; and a current dynamic constraint step, which adjusts the direct-axis current of the permanent magnet synchronous motor based on the dynamic safety current threshold, and keeps the direct-axis current within the safety current threshold. The application has the effects of further improving the overload current limiting and permanent magnet protection reliability of the permanent magnet synchronous motor and keeping the motor stable.

Description

Technical Field

[0001] This application relates to the field of motor control technology, and in particular to a backpack-type drive integrated permanent magnet synchronous motor control method and system. Background Technology

[0002] Backpack-type integrated permanent magnet synchronous motors are power units that integrate the permanent magnet synchronous motor body and drive controller in an external backpack-like manner. They are widely used in various industrial equipment that operates continuously and frequently starts and stops. These motors rely on a driver to achieve variable frequency speed regulation and closed-loop control. The rotor permanent magnet is the core functional component; control accuracy, overload protection capability, and the permanent magnet's anti-demagnetization performance are crucial to ensuring the long-term stable operation of the equipment. Once control malfunctions or permanent magnet demagnetization occurs, the motor torque and efficiency will decrease significantly, eventually rendering it unusable.

[0003] In related technologies, permanent magnet synchronous motors are generally used with general-purpose drivers, which are divided into two forms: external split drivers and built-in integrated drivers. General-purpose drivers have not been optimized for backpack-type integrated structures, resulting in low matching with the motor body. Under low-speed conditions, torque pulsation and running vibration are prone to occur. When frequently reversing, accelerating, or decelerating, the control logic response is lagging. The overload protection threshold setting of traditional drive solutions is simple and cannot distinguish between short-term impact loads and continuous overload loads, resulting in insufficient flexibility of protection logic.

[0004] Currently available backpack-style integrated permanent magnet synchronous motors, while achieving physical integration of the drive and motor, still rely on common control strategies, exhibiting significant technical shortcomings. On one hand, when equipment frequently starts and stops or experiences sudden load changes, the driver is prone to outputting instantaneous high currents, far exceeding the tolerance range of the permanent magnet. Long-term operation can cause irreversible demagnetization of the permanent magnet, leading to permanent degradation of motor performance. On the other hand, existing control programs lack sufficient optimization for acceleration / deceleration processes and braking timing. Under impact loads, this not only results in poor operational stability but also easily triggers driver overcurrent faults and alarm shutdowns. Furthermore, encoder signals are susceptible to interference from internal wiring within the module, further affecting the accuracy of position and speed closed-loop control.

[0005] Therefore, existing backpack-type integrated permanent magnet synchronous motors lack optimizations for control logic, overload current limiting, and permanent magnet protection functions, which is not conducive to increasing efficiency. Summary of the Invention

[0006] To further improve the overload current limiting and permanent magnet protection effect of permanent magnet synchronous motors and maintain the stability of motor operation, this application provides a backpack-type integrated drive permanent magnet synchronous motor control method and system.

[0007] Firstly, this application provides a control method for a backpack-type integrated permanent magnet synchronous motor: A control method for a backpack-style integrated permanent magnet synchronous motor includes: The operation parameter detection step involves collecting operation parameters that reflect the real-time working status of the motor and the status of the permanent magnet, and integrating them to generate real-time status parameters. The magnet state analysis step includes a magnet demagnetization analysis strategy, which is used to analyze the demagnetization risk index of permanent magnets under real-time state parameters. The critical current analysis step involves analyzing the demagnetization risk index using a dynamically adjusted model with a preset current safety threshold to generate a dynamic range of safe current thresholds. The current dynamic constraint step adjusts the direct-axis current of the permanent magnet synchronous motor based on a dynamic safe current threshold to keep the direct-axis current within the safe current threshold.

[0008] By adopting the above technical solution, the entire control process is completed in sequence, including collecting the operating parameters of the motor body and permanent magnet, quantifying the risk of permanent magnet demagnetization, solving the dynamic safety current threshold, and constraining the direct axis current. This helps to control the reverse direct axis current from the electrical source that causes permanent magnet demagnetization, adapts to the operating condition of simultaneous heating of the backpack-type integrated motor and driver with dual heat sources, reduces the probability of irreversible demagnetization of permanent magnets, improves the stability of torque output during long-term continuous operation of the motor, and extends the working cycle of the permanent magnet to maintain rated performance.

[0009] Optionally, the magnet demagnetization analysis strategy includes: A demagnetization analysis model based on the characteristics of operating parameters is pre-constructed, including permanent magnet temperature and demagnetization current; The demagnetization risk index of the permanent magnet under the current real-time state parameters is calculated based on the demagnetization analysis model, which uses the following formula: ; ; in, The d-axis current is the rated critical demagnetizing current at the reference temperature, and k is the temperature decay coefficient of the permanent magnet. Real-time temperature estimation for permanent magnets Preset reference temperature; This is a real-time demagnetization risk index; This represents the real-time d-axis current of the motor. These are the safe operating temperature and critical operating temperature of the permanent magnet, respectively. The preset weighting coefficients are used to classify risk levels based on the numerical range of the demagnetization risk index, with different risk levels corresponding to different current constraint intensities.

[0010] By adopting the above technical solution, a two-layer calculation model is built using two core parameters: permanent magnet temperature and reverse direct-axis demagnetizing current, to solve the critical demagnetizing direct-axis current and quantify the demagnetizing risk index respectively. Then, a current constraint strategy with corresponding strength is matched according to the risk range. This helps to simultaneously conduct state assessment of the two types of permanent magnet demagnetizing causes, reduce the assessment deviation caused by the judgment of a single electrical parameter, make the current limiting force fit the current danger level of the permanent magnet, and reduce the motor power loss caused by excessive current limiting.

[0011] Optionally, the current dynamic constraint step is further configured with a feedforward peak adjustment strategy for dynamically adjusting the direct-axis current, including: Extract the direct-axis current component corresponding to the direct-axis current in the issued current command and compare it with the real-time safe current threshold to determine the instantaneous peak component. The feedforward circuit weakens the peak current exceeding the safe current threshold and generates a safe adjustment command to be output to the inverter for output current regulation. The inverter output current is continuously checked, and the direct-axis current is dynamically maintained within the safe current threshold.

[0012] By adopting the above technical solution, the direct-axis current component in the upper-level command is extracted in advance and compared with the real-time dynamic safety threshold. The excessive current spike is weakened in advance by the feedforward link before the compliant adjustment command is issued. At the same time, the inverter output current is continuously verified to form a closed-loop control, which helps to improve the adjustment lag problem of traditional feedback control. Intervention is completed before the load impact generates dangerous current spikes, shortening the duration of large reverse direct-axis current acting on the permanent magnet and improving the response speed of direct-axis current control.

[0013] Optionally, the feedforward peak adjustment strategy further includes a peak-shaving adaptive sub-strategy: The instantaneous peak components generated by the motor are analyzed to determine the corresponding peak operating condition type and match the corresponding feedforward peak reduction weight ratio in the preset feedforward adjustment database. Based on the feedforward peak reduction weight ratio, the generation of large-amplitude reverse direct-axis current is suppressed, and the current maintenance command is output when the direct-axis current is within the safe current threshold.

[0014] By adopting the above technical solution, the feedforward peak reduction weight is matched with the corresponding ratio according to different instantaneous impact conditions. When the motor has no current spikes in steady state, the original output command is directly retained without intervention. This helps to take into account the permanent magnet demagnetization protection requirements in transient conditions and the rated power output capability in steady state conditions. It avoids insufficient motor output caused by a fixed peak reduction ratio throughout the process, adapts to the variable load scenarios of logistics sorting and AGV trolleys with frequent start-stop speed changes, and broadens the load types that the whole control strategy can be adapted to.

[0015] Optionally, the dynamic adjustment model for the safety current threshold includes: The dynamic total current limit value is calculated by adjusting the narrowing range of the current limit based on the demagnetization risk index, and combining the rated peak current of the motor and the current critical demagnetization direct-axis current. The dynamic adjustment model for the safe current threshold adopts the following formula: ; in, This is the dynamic total current limit value; The peak current specified by the manufacturer for the motor; Real-time temperature estimation for permanent magnets; Preset a safe operating temperature for the permanent magnet; This is the critical temperature for irreversible demagnetization of permanent magnets. The current derating weighting factor is the temperature dimension. This represents the nonlinear adjustment index corresponding to the temperature exceeding the threshold. This refers to the real-time direct-axis current of the motor. This is the critical demagnetizing direct-axis current corresponding to the current permanent magnet temperature; This is the nonlinear adjustment index corresponding to the proportion of direct-axis demagnetizing current.

[0016] By adopting the above technical solution, a dynamic current limit calculation model is built by integrating multiple parameters such as the rated peak current of the motor, the over-temperature range of the permanent magnet, and the proportion of reverse direct-axis current. The current narrowing range corresponding to temperature and demagnetizing current is corrected by nonlinear exponents, which helps to dynamically narrow the safe current range in line with the physical characteristics of the permanent magnet's reduced anti-demagnetization ability under high temperature environment. This improves the matching degree between the safe current threshold and the real-time thermal and electrical state of the motor, and reduces the protection redundancy or insufficient protection caused by fixed current threshold.

[0017] Optionally, the operating parameter detection step is further configured with a load-identifying dynamic overcurrent protection strategy, which includes: The motor load type is determined by analyzing motor current and speed data through high-frequency sampling. The load types include instantaneous impact load, periodic pulsating load, and continuous overload load. The number of impact energy accumulations is calculated based on the instantaneous impact load type. When the number of impact energy accumulations reaches the preset baseline number of impacts, current limiting protection is implemented and a current limiting window timer is generated. After the preset protection window duration is reached, the number of impact energy accumulations is recalculated. Based on the type of continuous overload, the motor output torque and output current are gradually reduced in a segmented, stepped manner. After each level of load reduction, the motor maintains a preset stable duration and simultaneously outputs an overload warning signal.

[0018] By adopting the above technical solution, three differentiated load types are divided based on the current and speed data collected at high frequency. An impact energy accumulation mechanism and protection timing window are set for instantaneous impact loads, and a graded step load reduction is implemented for continuous overload loads with simultaneous output of early warning signals. This helps to distinguish between the slight impact loads that the equipment can withstand in the short term and the continuous overload loads that will cause long-term damage, reduce the interference caused by frequent current limiting shutdowns to material transfer operations on the production line, and gradually reduce the motor load and reduce the temperature rise of the windings and permanent magnets under overload conditions.

[0019] Optionally, the current dynamic constraint step is further configured with a low-speed torque ripple suppression strategy, which includes: An iterative learning control framework is adopted to collect torque error signals or current error signals after each electrical cycle is completed. Based on the iterative learning control framework, the harmonic current compensation component corresponding to the next electric cycle is updated with a preset iterative update strategy to suppress torque pulsation and direct-axis current fluctuations generated under low-speed conditions.

[0020] By adopting the above technical solution, relying on the iterative learning control framework, and combining the update criterion of introducing the forgetting factor to iteratively optimize the harmonic current compensation component on an electric cycle basis, it helps to continuously offset the current fluctuations caused by periodic harmonics in the low-speed range, gradually reduce the torque pulsation amplitude under low-speed conditions, improve the smoothness of low-speed conveying and sorting operations of backpack motors, and reduce the cumulative demagnetization damage caused by repeated action of fluctuating current on permanent magnets.

[0021] Optionally, the current dynamic constraint step is further configured with a start-stop speed change smooth control strategy, which includes: A seven-segment curve is used to complete the motor speed planning, and multi-source compensation is performed by superimposing acceleration feedforward, friction feedforward, and load torque feedforward. The maximum acceleration is dynamically adjusted based on an adaptive curve model to reduce the current surge during start-stop and speed change processes.

[0022] By adopting the above technical solution, speed planning is completed using a seven-segment curve and multi-dimensional feedforward compensation is superimposed. The maximum jerk value is corrected in real time by relying on an adaptive model. This helps to smooth the current change process during motor start-up, commutation and speed change, reduce the probability of generating large reverse direct-axis current under dynamic conditions, reduce the continuous effect of alternating demagnetizing magnetic field on permanent magnets during frequent speed change, and optimize the working environment of permanent magnets under dynamic loads.

[0023] Secondly, this application provides a backpack-type integrated permanent magnet synchronous motor control system, which adopts the following technical solution: A backpack-style integrated permanent magnet synchronous motor control system includes: The operating parameter detection module collects operating parameters that reflect the real-time working status of the motor and the status of the permanent magnet, and integrates them to generate real-time status parameters. The magnet state analysis module is configured with a magnet demagnetization analysis strategy, which is used to analyze the demagnetization risk index of permanent magnets under real-time state parameters. The critical current analysis module analyzes the current based on the demagnetization risk index and uses a preset current safety threshold dynamic adjustment model to generate a dynamic range of safe current thresholds. The current dynamic constraint module adjusts the direct-axis current of the permanent magnet synchronous motor based on a dynamic safe current threshold to keep the direct-axis current within the safe current threshold.

[0024] By adopting the above technical solutions, each module works together to complete parameter acquisition, demagnetization risk analysis, safety threshold calculation, and direct-axis current constraint complete control logic. This helps to make the functional division of hardware units clear, reduce the coupling degree of main control operation, adapt to the integrated hardware architecture of backpack-type external driver, and facilitate modular debugging and fault diagnosis of equipment on site.

[0025] In summary, this application includes at least one of the following beneficial technical effects: 1. By collecting operating parameters of the motor body and permanent magnet, quantifying the risk of permanent magnet demagnetization, solving the dynamic safety current threshold, and implementing a complete control process of direct-axis current closed-loop constraint, it helps to control the reverse direct-axis current from the electrical source that causes permanent magnet demagnetization. It is suitable for the operating condition of simultaneous heating of the backpack-type drive integrated motor and the driver with dual heat sources, reduces the probability of irreversible demagnetization of permanent magnet, improves the stability of torque output during long-term continuous operation of the motor, and extends the working cycle of the permanent magnet to maintain rated performance. 2. Based on high-frequency acquired current and speed data, three differentiated load types are classified. For instantaneous impact loads, an impact energy accumulation mechanism and protection timing window are set up. For continuous overload loads, a graded step load reduction is implemented and a warning signal is output simultaneously. This helps to distinguish between the slight impact loads that the equipment can withstand in the short term and the continuous overload loads that will cause long-term damage. It reduces the interference caused by frequent current limiting shutdowns to material transfer operations on the production line. At the same time, under overload conditions, the motor load is gradually reduced to reduce the temperature rise of the windings and permanent magnets. 3. The iterative learning control framework, combined with the update criterion that introduces a forgetting factor, iteratively optimizes the harmonic current compensation component on a per-electric-cycle basis. This helps to continuously offset the current fluctuations caused by periodic harmonics in the low-speed range, gradually reduce the torque pulsation amplitude under low-speed conditions, improve the smoothness of low-speed conveying and sorting operations of backpack motors, and reduce the cumulative demagnetization damage caused by repeated action of fluctuating current on permanent magnets. Attached Figure Description

[0026] Figure 1 This is a flowchart of steps S100 to S400 in this application.

[0027] Figure 2 This is a flowchart of steps S401 to S403 in this application.

[0028] Figure 3 This is a flowchart of steps S404 to S405 in this application.

[0029] Figure 4 This is a flowchart of steps S406 to S408 in this application.

[0030] Figure 5 This is a flowchart of steps S409 to S410 in this application.

[0031] Figure 6 This is a flowchart of steps S411 to S412 in this application. Detailed Implementation

[0032] To make the purpose, technical solution, and advantages of this application clearer, the following description is provided in conjunction with the appendix. Figure 1-6 The present application will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the application.

[0033] The embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0034] This application discloses a control method for a backpack-type integrated permanent magnet synchronous motor. By sequentially completing the entire control process of acquiring the operating parameters of the motor body and permanent magnet, quantifying and analyzing the risk of permanent magnet demagnetization, solving the dynamic safety current threshold, and constraining the direct axis current, it helps to control the reverse direct axis current from the electrical source that causes permanent magnet demagnetization. It is suitable for the operating condition of simultaneous heating of the backpack-type integrated motor and driver with dual heat sources, reduces the probability of irreversible demagnetization of permanent magnet, improves the stability of torque output during long-term continuous operation of the motor, and extends the working cycle of the permanent magnet maintaining rated performance.

[0035] Reference Figure 1 The method flow of the backpack-type drive integrated permanent magnet synchronous motor control method includes the following steps: Step S100: Operation parameter detection step, collecting operation parameters that reflect the real-time working status of the motor and the status of the permanent magnet, and integrating them to generate real-time status parameters; Step S200: Magnet state analysis step, configured with a magnet demagnetization analysis strategy, used to analyze the demagnetization risk index of permanent magnets under real-time state parameters; Step S300: Critical current analysis step, based on the demagnetization risk index, analyzes the current safety threshold dynamically by adjusting the model to generate a dynamic range of safe current threshold. Step S400: Current dynamic constraint step, adjusting the direct axis current of the permanent magnet synchronous motor based on the dynamic safe current threshold to keep the direct axis current within the safe current threshold.

[0036] In step S100, the operating parameter detection step is a standardized detection scheme for high-frequency acquisition and integration of full-domain operating parameters, targeting the operating characteristics of backpack-type integrated drive motors with dual heat sources, frequent start-stop, and variable loads. This provides complete and accurate basic data for subsequent permanent magnet demagnetization risk analysis, current threshold adjustment, and overcurrent protection control. Operating parameters refer to core data that can intuitively reflect the motor's operating conditions, electrical status, and permanent magnet health status, including basic parameters such as motor current, speed, output torque, permanent magnet temperature, and direct-axis current. These are the core basis for motor status determination and control strategy adjustment. Real-time status parameters refer to the unified, integrated, and classified full-domain operating data set of the motor, realizing the integrated data presentation of the motor's mechanical operating status and the permanent magnet's thermal and electrical status, providing standardized data support for the linkage calculation of various control strategies.

[0037] In step S200, the magnet demagnetization analysis strategy is a quantitative assessment scheme for permanent magnet demagnetization risk, designed to address the characteristics of the backpack-type integrated motor driver and motor body heating synchronously and the tendency of reverse demagnetizing current to impact the permanent magnet. This scheme is used to accurately determine the real-time demagnetization risks of the permanent magnet, quantify the demagnetization risk index, and provide precise risk basis for dynamic current constraints. The demagnetization risk index is a core assessment parameter that quantitatively characterizes the probability and severity of irreversible demagnetization under the current operating conditions of the permanent magnet. It serves as the benchmark for differentiated current constraints and protection strategy adjustments. The index value range can be used to divide the demagnetization risk into gradient levels, corresponding to different intensities of current control and protection logic, achieving precise risk-level protection.

[0038] In step S300, the dynamic adjustment model for the current safety threshold is a nonlinear dynamic calculation model adapted to the temperature decay characteristics of permanent magnets and the influence law of reverse demagnetizing current. It is used to replace the traditional fixed current threshold scheme. Based on the aforementioned demagnetization risk index, the current limit is corrected in real time, realizing the real-time adaptive adjustment of the safe current limit according to the motor's thermal and electrical states. The safe current threshold of the dynamic range refers to the compliant current range dynamically calculated by combining the motor's rated parameters, the real-time temperature of the permanent magnet, the demagnetization risk level, and the direct-axis current state. It is the core control boundary for constraining the motor's output current, avoiding permanent magnet demagnetization, and suppressing overcurrent faults.

[0039] In step S400, the current dynamic constraint step is an integrated control mechanism based on the permanent magnet demagnetization risk level and dynamic safety current threshold. It achieves closed-loop control of direct-axis current, proactive intervention for current spikes, and precise suppression of operational fluctuations. This is used to avoid the potential for irreversible demagnetization of permanent magnets from the electrical source, while simultaneously addressing operational defects such as low-speed torque pulsation, start-stop speed change shocks, and load fluctuation jitter. Direct-axis current is a core electrical parameter affecting the magnetization state of the permanent magnet in a permanent magnet synchronous motor, and reverse direct-axis current is a key cause of permanent magnet demagnetization. Current dynamic constraint is the core control logic that ensures compliant current output and stable operation of the motor under all operating conditions through multi-dimensional regulation.

[0040] It should be noted that the magnet demagnetization analysis strategy in S200 includes the following schemes: A demagnetization analysis model based on the characteristics of operating parameters is pre-constructed, including permanent magnet temperature and demagnetization current; The demagnetization risk index of the permanent magnet under the current real-time state parameters is calculated based on the demagnetization analysis model, which uses the following formula: ; ; in, The d-axis current is the rated critical demagnetizing current at the reference temperature, and k is the temperature decay coefficient of the permanent magnet. Real-time temperature estimation for permanent magnets Preset reference temperature; This is a real-time demagnetization risk index; This represents the real-time d-axis current of the motor. These are the safe operating temperature and critical operating temperature of the permanent magnet, respectively. The preset weighting coefficients are used to classify risk levels based on the numerical range of the demagnetization risk index, with different risk levels corresponding to different current constraint intensities.

[0041] Based on the critical demagnetizing current model, and integrating the dual-dimensional causes of electrical and thermal demagnetizing, a weighted quantitative solution is used to calculate the real-time demagnetizing risk index of permanent magnets, and the formula for calculating the risk index is derived: ; Irreversible demagnetization of permanent magnets is caused by the coupling of two core factors: reverse direct-axis current impact and over-temperature aging. Therefore, the risk index adopts a two-term weighted coupling structure. The first term is the electrical demagnetization risk term, which uses a max function to screen effective reverse demagnetizing currents and avoids interference from forward excitation currents on risk assessment. The ratio of real-time reverse direct-axis current to the current temperature critical demagnetizing current characterizes the electrical impact risk. The second item is the thermal demagnetization risk item. Over-temperature conditions are screened using a max function, and the ratio of the actual over-temperature amplitude to the extreme over-temperature range characterizes the thermal aging risk. Preset weighting coefficients w1 and w2 are used to match the influence weights of electrical demagnetization and thermal demagnetization, respectively, and a normalized demagnetization risk index R(t) is obtained through weighted coupling. Risk levels are divided according to the R(t) value range, and different levels are matched with differentiated current constraint strengths to achieve graded and precise protection. In the formula, R(t) is the real-time demagnetization risk index; This represents the real-time d-axis current of the motor. , These are the safe operating temperature and critical operating temperature of the permanent magnet, respectively. , These are the preset weighting coefficients.

[0042] What needs to be further disclosed is that the dynamic adjustment model for the safe current threshold includes: The dynamic total current limit value is calculated by adjusting the narrowing range of the current limit based on the demagnetization risk index, and combining the rated peak current of the motor and the current critical demagnetization direct-axis current. The dynamic adjustment model for the safe current threshold adopts the following formula: ; in, This is the dynamic total current limit value; The peak current specified by the manufacturer for the motor; Real-time temperature estimation for permanent magnets; Preset a safe operating temperature for the permanent magnet; This is the critical temperature for irreversible demagnetization of permanent magnets. The current derating weighting factor is the temperature dimension. This represents the nonlinear adjustment index corresponding to the temperature exceeding the threshold. This refers to the real-time direct-axis current of the motor. This is the critical demagnetizing direct-axis current corresponding to the current permanent magnet temperature; This is the nonlinear adjustment index corresponding to the proportion of direct-axis demagnetizing current.

[0043] More specifically, the derivation principle of the formula is as follows: A permanent magnet possesses a rated critical demagnetization resistance at a reference temperature T0, corresponding to a reference critical demagnetization direct-axis current Id0. When the real-time temperature of the permanent magnet deviates from the reference temperature, high temperatures will damage the magnetic domain structure of the permanent magnet; the higher the temperature, the more severe the magnetic performance decay, and the smaller the critical demagnetization current. By introducing a permanent magnet temperature decay coefficient k to quantify temperature sensitivity, and using a natural exponential function to fit the nonlinear decay characteristics of magnetic performance, the degradation law of the permanent magnet's demagnetization resistance under high-temperature conditions is accurately reproduced, avoiding the error problem of traditional fixed critical current estimation.

[0044] The derivation principle of the formula is as follows: The overall formula adopts a coupled structure of rated peak current and two-dimensional nonlinear loss correction, which is divided into three logic layers: a reference current layer, a temperature derating correction layer, and a demagnetizing current correction layer. The first layer is the reference current, which is the peak current specified by the motor at the factory. The first layer is the maximum current limit, ensuring that the current limiting range does not exceed the rated capacity of the motor hardware. The second layer is temperature nonlinear derating correction, which uses the max function to screen for over-temperature conditions and introduces a nonlinear adjustment index β to simulate the accelerated deterioration of the permanent magnet's anti-demagnetization capability after over-temperature. It is combined with the temperature derating weighting coefficient α to quantify the narrowing of the current limit due to temperature, avoiding the problem of insufficient high-temperature protection caused by linear derating. The third layer is demagnetizing current nonlinear correction, which uses the max function to screen for effective reverse demagnetizing current and introduces a nonlinear adjustment index γ to characterize the destructive surge characteristics of large-scale reverse current. It is combined with the real-time critical demagnetizing current to complete the correction of current impact loss.

[0045] The three-layer structure with progressive coupling correction can dynamically narrow the safe current range based on the real-time temperature of the permanent magnet, the real-time reverse current, and the demagnetization risk level, achieving adaptive control that ensures power supply in low-risk conditions and strong protection in high-risk conditions.

[0046] Reference Figure 2 The current dynamic constraint step is also configured with a feedforward peak adjustment strategy for dynamically adjusting the direct-axis current, including: Step S401: Extract the direct-axis current component corresponding to the direct-axis current in the issued current command, and compare and analyze it with the real-time safe current threshold to determine the instantaneous peak component. Step S402: Based on the feedforward circuit, the peak value exceeding the safe current threshold is weakened, and a safe adjustment command is generated and output to the inverter to adjust the output current. Step S403: Continuously check the current output by the inverter and dynamically maintain the direct-axis current within the safe current threshold.

[0047] In S401, the direct-axis current component is the core current parameter in the upper-level control command that directly affects the magnetization state of the permanent magnet, and is a key control target that can trigger instantaneous demagnetization risks. The real-time safe current threshold is the compliance current boundary that is updated in real time by the aforementioned dynamic adjustment model. The instantaneous spike component refers to the excess current portion of the command's direct-axis current component that exceeds the dynamic safe current threshold. Command component extraction and threshold comparison are the preliminary judgment steps for feedforward intervention, which can identify dangerous current spikes caused by load impacts and operating condition switching in advance, solving the problem of lag in traditional feedback control.

[0048] In the S402, the feedforward loop is a front-end control unit independent of the feedback closed loop, which can intervene and correct before the excessive current is output; peak reduction is a precise suppression operation for instantaneous large-value reverse direct-axis current, used to shorten the duration of dangerous current acting on the permanent magnet; the safety adjustment command is a compliant control command that has been peak-shaving corrected and is fully adapted to the real-time safety current threshold. The inverter adjusts the current output according to the command to avoid instantaneous demagnetization damage from the source.

[0049] In S403, continuous verification is a high-frequency, real-time closed-loop verification mechanism. Based on the actual output current of the inverter, it dynamically compares the deviation between the theoretical adjustment command and the actual output, corrects the control parameters in real time, and ensures that the direct-axis current is stably constrained within the dynamic safety range under all operating conditions and at all times. This avoids protection failure caused by a single feedforward adjustment deviation and improves the stability and accuracy of current constraint.

[0050] Reference Figure 3 The feedforward peak adjustment strategy also includes a peak-shaving adaptive sub-strategy: Step S404: Analyze the instantaneous peak components generated by the motor to determine the corresponding peak operating condition type and match the corresponding feedforward peak reduction weight ratio in the preset feedforward adjustment database; Step S405: Based on the feedforward peak clipping weight ratio, suppress the generation of large-amplitude reverse direct-axis current, and output a current maintenance command when the direct-axis current is within the safe current threshold.

[0051] In step S404, the instantaneous peak condition type is a differentiated load impact condition categorized based on the amplitude, duration, and frequency of current peaks, covering typical conditions of backpack motors such as start-stop impacts, speed change impacts, and sudden load impacts. The preset feedforward adjustment database is a standardized database storing the optimal peak-shaving parameters for various conditions, adapting to the diverse load scenarios of the motor. The feedforward peak-shaving weight ratio is a parameter that quantifies and matches the current suppression strength for each condition, achieving adaptive differentiated peak-shaving for each condition and avoiding the poor adaptability problem caused by uniform peak-shaving.

[0052] In step S405, the large-scale reverse direct-axis current is the core cause of the instantaneous irreversible demagnetization of the permanent magnet. By accurately suppressing it with adaptive weights matching the operating conditions, the risk of demagnetization under dynamic operating conditions can be greatly reduced. The steady-state command maintenance strategy can fully retain the original control command when the motor has no excessive current and the operating conditions are stable, without interfering with the rated power output of the motor, thus balancing the demagnetization protection performance of the permanent magnet and the operating efficiency of the motor.

[0053] Reference Figure 4 The operation parameter detection step is also configured with a load-identifying dynamic overcurrent protection strategy, which includes: Step S406: Analyze the motor current and speed data by high-frequency sampling to determine the motor load type, which includes instantaneous impact load, periodic pulsating load, and continuous overload load; High-frequency sampling is a high-density data acquisition mechanism designed for backpack-type integrated drive motors with frequent start-stop cycles and transient load conditions. It can capture motor current fluctuations, speed deviations, and other operating characteristics in real time. Load type classification is a logic based on current amplitude, speed stability, and load duration to classify operating conditions, enabling accurate differentiation of different severe load scenarios and providing an analytical basis for switching differentiated overcurrent protection logic. Instantaneous impact loads are short-term, intermittent, sudden load disturbances with no long-term damage risk; periodic pulsating loads are regularly fluctuating loads that easily cause continuous small current pulsations in the motor; continuous overload loads are loads that operate beyond rated conditions for extended periods, easily causing winding overheating and permanent magnet aging and demagnetization.

[0054] Step S407: Accumulate the number of impact energy based on the instantaneous impact load type. When the number of impact energy accumulations reaches the preset benchmark number of impacts, perform current limiting protection and generate a current limiting window timer. After the preset protection window duration is reached, re-accumulate the number of impact energy accumulations. The number of impact energy accumulations is a core statistical parameter for quantifying the cumulative loss of short-term impact loads, which can prevent the protection mechanism from being falsely triggered by a single minor load impact; the baseline number of impacts is a preset impact load protection judgment threshold used to distinguish between normal operating condition fluctuations and abnormally frequent impact faults; the current limiting window timer is a locking mechanism for preventing frequent start-stop protection. It locks the current limiting state within the protection window duration, and resets the count and restores normal detection logic after the window ends, effectively avoiding the interference of frequent start-stop current limiting on the continuous operation of the equipment.

[0055] Step S408: Based on the continuous overload load type, gradually reduce the motor output torque and output current in a segmented step manner, maintain a preset stable duration after each load reduction, and simultaneously output an overload warning signal.

[0056] Segmented, tiered load reduction is a flexible protection strategy adapted to continuous overload conditions. Unlike the traditional rigid protection method of instantaneous shutdown, it can effectively reduce the impact on equipment and production interruptions caused by sudden load changes. The preset stabilization time is the observation cycle of the working condition after a single-level load reduction, which is used to verify whether the load has returned to normal and avoid excessive load reduction affecting equipment operating efficiency. The overload warning signal is a visual and interactive status prompt signal, which facilitates on-site personnel to troubleshoot faults and adjust the working condition in a timely manner, realizing the integration of equipment protection and operation and maintenance early warning.

[0057] Reference Figure 5 The current dynamic constraint step is also configured with a low-speed torque ripple suppression strategy, which includes: Step S409: Using an iterative learning control framework, the torque error signal or current error signal is collected after each electrical cycle is completed; The iterative learning control framework is an adaptive optimization control framework that adapts to the low-speed periodic harmonic interference and repetitive operating condition disturbances of motors. It can achieve iterative correction of periodic errors for the inherent pulsation characteristics of low-speed operating conditions. The electrical cycle is the minimum electrical operating cycle corresponding to the rotation of the motor rotor and is the basic unit of iterative optimization. The torque error signal and current error signal are the core deviation parameters that characterize the torque pulsation and current fluctuations under low-speed operating conditions. They can accurately reflect the operating disturbance defects of the current cycle and provide reference data for subsequent harmonic compensation optimization.

[0058] Step S410: Based on the iterative learning control framework, update the harmonic current compensation component corresponding to the next electric cycle with a preset iterative update strategy to suppress torque pulsation and direct-axis current fluctuation generated under low-speed conditions.

[0059] The preset iterative update strategy is an iterative optimization criterion equipped with an adaptive forgetting factor, which can filter out interference from historical invalid data and continuously optimize the compensation accuracy. The harmonic current compensation component is a correction parameter set for the fluctuation error caused by motor body harmonics, wiring interference, and low-speed magnetic circuit inhomogeneity. Through cycle-by-cycle iterative updates, it can continuously offset the inherent disturbances in low-speed operation, gradually suppress periodic torque pulsation and direct-axis current fluctuations, improve the smoothness of low-speed operation of backpack motors, and reduce the cumulative demagnetization damage caused by repeated impacts of fluctuating current on permanent magnets.

[0060] Reference Figure 6 The current dynamic constraint step is also configured with a start-stop speed change smooth control strategy, which includes: Step S411: Use a seven-segment S-curve to complete the motor speed planning, and superimpose acceleration feedforward, friction feedforward, and load torque feedforward for multi-source compensation; The seven-segment S-curve speed planning is a smooth speed control algorithm that takes into account all operating conditions of motor start-stop, acceleration, constant speed, and deceleration. It can avoid the acceleration change problem caused by traditional linear acceleration and deceleration, and weaken the impact of operating condition switching from the speed level. Multi-source feedforward compensation is a targeted disturbance cancellation mechanism. Among them, acceleration feedforward is used to compensate for inertial disturbances during dynamic speed change, friction feedforward is used to cancel speed fluctuations and current changes caused by motor mechanical friction resistance, and load torque feedforward is used to adapt to external load disturbances in real time and compensate for current spikes caused by load torque changes in advance. Through multi-dimensional coupling compensation, the smoothness of motor operating condition switching is greatly improved.

[0061] Step S412: Dynamically adjust the maximum acceleration based on the adaptive S-curve model to reduce the current surge during start-stop and speed change processes.

[0062] The adaptive S-curve model can dynamically adjust the curve parameters according to the real-time load size, operating conditions, and permanent magnet demagnetization risk level of the motor, and match the optimal maximum acceleration in real time. Compared with the fixed parameter S-curve, this strategy can achieve adaptive adaptation of rapid response under light load conditions and smooth speed change under heavy load conditions. It can effectively suppress the instantaneous inrush current during the entire process of motor start-up, acceleration, and deceleration, avoid the generation of large reverse direct-axis current at the moment of operating condition switching, eliminate the cumulative demagnetization damage of permanent magnets caused by frequent start-up and speed change, and at the same time ensure the dynamic response performance of the motor.

[0063] Based on the same inventive concept, embodiments of the present invention provide a backpack-type integrated permanent magnet synchronous motor control system, comprising: The operating parameter detection module collects operating parameters that reflect the real-time working status of the motor and the status of the permanent magnet, and integrates them to generate real-time status parameters. The magnet state analysis module is configured with a magnet demagnetization analysis strategy, which is used to analyze the demagnetization risk index of permanent magnets under real-time state parameters. The critical current analysis module analyzes the current based on the demagnetization risk index and uses a preset current safety threshold dynamic adjustment model to generate a dynamic range of safe current thresholds. The current dynamic constraint module adjusts the direct-axis current of the permanent magnet synchronous motor based on a dynamic safe current threshold to keep the direct-axis current within the safe current threshold.

[0064] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional modules is used as an example. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. The specific working process of the system, device, and unit described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0065] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Any feature disclosed in this specification (including the abstract and drawings) may be replaced by other equivalent or similar features unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is only one example of a series of equivalent or similar features.

Claims

1. A control method for a backpack-type integrated permanent magnet synchronous motor, characterized in that, include: The operation parameter detection step involves collecting operation parameters that reflect the real-time working status of the motor and the status of the permanent magnet, and integrating them to generate real-time status parameters. The magnet state analysis step includes a magnet demagnetization analysis strategy, which is used to analyze the demagnetization risk index of permanent magnets under real-time state parameters. The critical current analysis step involves analyzing the demagnetization risk index using a dynamically adjusted model with a preset current safety threshold to generate a dynamic range of safe current thresholds. The current dynamic constraint step adjusts the direct-axis current of the permanent magnet synchronous motor based on a dynamic safe current threshold to keep the direct-axis current within the safe current threshold.

2. The backpack-type integrated permanent magnet synchronous motor control method according to claim 1, characterized in that, The magnet demagnetization analysis strategy includes: A demagnetization analysis model based on the characteristics of operating parameters is pre-constructed, including permanent magnet temperature and demagnetization current; The demagnetization risk index of the permanent magnet under the current real-time state parameters is calculated based on the demagnetization analysis model, which uses the following formula: ； ； in, The d-axis current is the rated critical demagnetizing current at the reference temperature, and k is the temperature decay coefficient of the permanent magnet. Real-time temperature estimation for permanent magnets Preset reference temperature; This is a real-time demagnetization risk index; This represents the real-time d-axis current of the motor. These are the safe operating temperature and critical operating temperature of the permanent magnet, respectively. The preset weighting coefficients are used to classify risk levels based on the numerical range of the demagnetization risk index, with different risk levels corresponding to different current constraint intensities.

3. The backpack-type integrated permanent magnet synchronous motor control method according to claim 1, characterized in that, The current dynamic constraint step is further configured with a feedforward peak adjustment strategy for dynamically adjusting the direct-axis current, including: Extract the direct-axis current component corresponding to the direct-axis current in the issued current command and compare it with the real-time safe current threshold to determine the instantaneous peak component. The feedforward circuit weakens the peak current exceeding the safe current threshold and generates a safe adjustment command to be output to the inverter for output current regulation. The inverter output current is continuously checked, and the direct-axis current is dynamically maintained within the safe current threshold.

4. The backpack-type integrated permanent magnet synchronous motor control method according to claim 3, characterized in that, The feedforward peak adjustment strategy also includes a peak-shaving adaptive sub-strategy: The instantaneous peak components generated by the motor are analyzed to determine the corresponding peak operating condition type and match the corresponding feedforward peak reduction weight ratio in the preset feedforward adjustment database. Based on the feedforward peak reduction weight ratio, the generation of large-amplitude reverse direct-axis current is suppressed, and the current maintenance command is output when the direct-axis current is within the safe current threshold.

5. The backpack-type integrated permanent magnet synchronous motor control method according to claim 2, characterized in that, The dynamic adjustment model for the safe current threshold includes: The dynamic total current limit value is calculated by adjusting the narrowing range of the current limit based on the demagnetization risk index, and combining the rated peak current of the motor and the current critical demagnetization direct-axis current. The dynamic adjustment model for the safe current threshold adopts the following formula: ； in, This is the dynamic total current limit value; The peak current specified by the manufacturer for the motor; Real-time temperature estimation for permanent magnets; Preset a safe operating temperature for the permanent magnet; This is the critical temperature for irreversible demagnetization of permanent magnets. The current derating weighting factor is the temperature dimension. This represents the nonlinear adjustment index corresponding to the temperature exceeding the threshold. This refers to the real-time direct-axis current of the motor. This is the critical demagnetizing direct-axis current corresponding to the current permanent magnet temperature; This is the nonlinear adjustment index corresponding to the proportion of direct-axis demagnetizing current.

6. The backpack-type integrated permanent magnet synchronous motor control method according to claim 1, characterized in that, The operating parameter detection step is further configured with a load-identifying dynamic overcurrent protection strategy, which includes: The motor load type is determined by analyzing motor current and speed data through high-frequency sampling. The load types include instantaneous impact load, periodic pulsating load, and continuous overload load. The number of impact energy accumulations is calculated based on the instantaneous impact load type. When the number of impact energy accumulations reaches the preset baseline number of impacts, current limiting protection is implemented and a current limiting window timer is generated. After the preset protection window duration is reached, the number of impact energy accumulations is recalculated. Based on the type of continuous overload, the motor output torque and output current are gradually reduced in a segmented, step-by-step manner. After each level of load reduction, the motor maintains a preset stable duration and simultaneously outputs an overload warning signal.

7. The backpack-type integrated permanent magnet synchronous motor control method according to claim 1, characterized in that, The current dynamic constraint step is further configured with a low-speed torque ripple suppression strategy, which includes: An iterative learning control framework is adopted to collect torque error signals or current error signals after each electrical cycle is completed. Based on the iterative learning control framework, the harmonic current compensation component corresponding to the next electric cycle is updated with a preset iterative update strategy to suppress torque pulsation and direct-axis current fluctuations generated under low-speed conditions.

8. The backpack-type integrated permanent magnet synchronous motor control method according to claim 1, characterized in that, The current dynamic constraint step is further configured with a start-stop speed change smooth control strategy, which includes: A seven-segment curve is used to complete the motor speed planning, and multi-source compensation is performed by superimposing acceleration feedforward, friction feedforward, and load torque feedforward. The maximum acceleration is dynamically adjusted based on an adaptive curve model to reduce the current surge during start-stop and speed change processes.

9. A backpack-type integrated permanent magnet synchronous motor control system, employing the method described in any one of claims 1 to 8, characterized in that, include: The operating parameter detection module collects operating parameters that reflect the real-time working status of the motor and the status of the permanent magnet, and integrates them to generate real-time status parameters. The magnet state analysis module is configured with a magnet demagnetization analysis strategy, which is used to analyze the demagnetization risk index of permanent magnets under real-time state parameters. The critical current analysis module analyzes the current based on the demagnetization risk index and uses a preset current safety threshold dynamic adjustment model to generate a dynamic range of safe current thresholds. The current dynamic constraint module adjusts the direct-axis current of the permanent magnet synchronous motor based on a dynamic safe current threshold to keep the direct-axis current within the safe current threshold.

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