Margin adaptive current reduction control method and system based on dynamic stability margin

Abstract

The application discloses a margin-keeping adaptive current reduction control method and system based on a dynamic stability boundary, relates to the technical field of sensorless vector control of permanent magnet synchronous motors, and comprises the following steps: constructing a motor basic model of a sliding mode observer without a sensor, and establishing a dynamic model of a segmented operation and a misalignment angle of I-f starting; obtaining a dynamic stability boundary based on an equal-area criterion; deducing a lower limit of a safe current with a minimum dynamic constraint according to the dynamic stability boundary; solving a maximum current reduction rate allowed at the current time through a margin-keeping adaptive variable-slope current reduction algorithm; stopping the current from being reduced when the current reaches the lower limit of the safe current until the misalignment angle meets a switching condition, preloading a speed loop integrator to a terminal current command of stage II, and smoothly switching to closed-loop vector control of the sliding mode observer; and ensuring that step-out does not occur during the whole transition phase against a set-amplitude load step disturbance.

Description

Technical Field

[0001] This invention relates to the field of sensorless vector control technology for permanent magnet synchronous motors, and more specifically, to a margin-based adaptive current reduction control method and system based on dynamic stability boundaries. Background Technology

[0002] Permanent magnet synchronous motors rely on back EMF sliding mode observers for sensorless control. However, the back EMF amplitude is extremely low in the low-speed range, making it impossible for the observer to accurately extract the rotor position, resulting in a low-speed observation blind zone. The industry generally adopts the If segmented start-up scheme to solve this problem. The start-up is divided into two stages: Stage I (acceleration stage), a constant q-axis current is given in the virtual synchronous coordinate system, the frequency ramps up, and the motor speeds up by relying on the misalignment angle between the virtual axis and the rotor's real axis to form a self-stabilizing torque; Stage II (constant speed current reduction transition stage), after the motor reaches the minimum speed usable by the observer, the given frequency is kept constant, the q-axis current amplitude is gradually reduced, the misalignment angle between the virtual axis and the rotor's real axis is reduced, and after the angle is aligned, the control switches to the sliding mode observer closed-loop FOC control to suppress the instantaneous torque pulsation during the switching.

[0003] The aforementioned existing technologies have the following limitations:

[0004] 1. The current reduction curves in the current stage II are all empirically designed, and most of them adopt linear reduction with a fixed slope, parabolic reduction, or simple power compensation to reduce the current. They have not established a quantitative mathematical relationship between the real-time stability margin and the given current amplitude, and cannot quantitatively evaluate the motor's ability to resist load disturbances during the current reduction process.

[0005] 2. As the current decreases, the rotor misalignment angle continues to decrease, and the self-stabilizing recovery torque stiffness of the motor is greatly reduced. Even a small load fluctuation can cause the misalignment angle to cross 0°, resulting in the motor losing synchronization and failing to start. Under light load conditions, the stator current is low, and the observation error of the sliding mode observer is further amplified, which sharply increases the risk of losing synchronization.

[0006] 3. Traditional linear current reduction strategies do not have a minimum safe current constraint. If a step disturbance in the load occurs in the later stage of current reduction, the current is already below the critical value for maintaining dynamic stability, which can easily lead to instability and shutdown. Parabolic current reduction only slows down the rate of descent at the end and does not adaptively adjust the current reduction rate according to the real-time stability margin. Power compensation schemes require additional PI control parameters, which are complex to tune and are only applicable to steady-state conditions.

[0007] 4. Existing technologies rely solely on static stability boundaries to determine ultimate load capacity, neglecting the transient oscillation effect of rotor angle caused by load disturbances. Theory and simulation have shown that the peak value of the transient angle caused by the disturbance can reach twice the steady-state offset. The static boundary judgment standard is too lenient and poses a serious safety hazard.

[0008] Therefore, this application is hereby submitted. Summary of the Invention

[0009] The purpose of this invention is to provide a margin-adaptive current reduction control method and system based on dynamic stability boundaries. Addressing the shortcomings of traditional If-stage startup current reduction strategies, such as lack of quantitative constraints on stability margin, fixed current reduction rate, reliance on static stability boundaries to determine safety thresholds, and susceptibility to loss of synchronization under load disturbances, this solution reserves a specified disturbance rejection margin throughout the process. It adaptively adjusts the current reduction rate based on real-time dynamic stability margin, forming a current curve that first drops rapidly and then gradually decreases. It automatically limits the current to not fall below the minimum dynamic stability safety threshold, reducing startup copper losses while ensuring that the system resists load step disturbances of a set amplitude without losing synchronization throughout the entire transition phase.

[0010] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0011] Firstly, this application provides a margin-based adaptive current reduction control method based on dynamic stability boundaries, including the following specific steps:

[0012] Construct a sensorless motor basic model for a sliding mode observer, and establish a dynamic model of segmented operation and misalignment angles for If start-up;

[0013] Based on the basic and dynamic models of the motor, the dynamic stability boundary is obtained by solving the problem using the equal area criterion.

[0014] Based on the dynamic stability boundary, derive the lower limit of the safe current with the minimum dynamic constraint.

[0015] The maximum allowable current drop rate at the current moment is solved by the margin-adaptive variable slope current reduction algorithm, and the operation is performed based on the maximum current drop rate.

[0016] When the current reaches the lower limit of the safe current, it stops decreasing until the misalignment angle meets the switching condition. Then, the speed loop integrator is preloaded to the end current command of stage II and smoothly switched to the closed-loop vector control of the sliding mode observer.

[0017] Based on the above technical solution, the present invention can be further improved as follows.

[0018] Furthermore, the aforementioned basic motor model includes a steady-state model. The stator voltage equation, back electromotive force equation, and sliding mode observer model in the coordinate system are as follows: The stator voltage equation is: ; The back electromotive force equation is: ; The sliding mode observer model is as follows: ; , ; In the above formula, , , These represent the stator voltage charge, current vector, and back electromotive force vector, respectively. and These are the stator resistance and stator inductance, respectively. It is a permanent magnet flux linkage. The angular velocity of the motor. Indicates the position of the motor rotor. This is an S-shaped switching function used to suppress oscillations. ; This indicates that the observer stability requires gain, and .

[0019] Furthermore, the aforementioned If start-up includes acceleration phase I and constant-speed transition phase II; wherein:

[0020] During acceleration phase I, the current along the q-axis of the virtual coordinate system remains constant. A given electrical frequency is introduced via a ramp-up, and a self-stabilizing electromagnetic torque is generated by the offset angle, expressed as: ; In the formula, For electromagnetic torque, For extreme logarithms, Represents the q-axis current. Indicates the misalignment angle. It is a permanent magnet flux linkage. , These represent the d-axis inductance and the q-axis inductance, respectively.

[0021] In the constant-speed transition phase II, the given frequency remains constant, and the current reduction process begins. Based on the established second-order electromechanical equation of the misalignment angle, the transfer function from load disturbance to misalignment angle deviation is linearized and expressed as: ,in: ; In the formula, For load torque, For rotational inertia, Indicates the coefficient of viscous friction. This is the equilibrium point during the constant speed phase.

[0022] Furthermore, the dynamic stable boundary obtained based on the equal area criterion is as follows:

[0023] Ignoring viscous friction, we establish the dynamic equations for rotor oscillation under disturbance, and derive the constant-area stability criterion using energy conservation: ; ; In the formula, For load torque, For rotational inertia, For extreme logarithms, Indicates the misalignment angle. For the load torque, when at the initial angle and peak position When the kinetic energy is set to zero at all points, A step transition to the new load can be derived. The required equal area condition.

[0024] Furthermore, the aforementioned lower limit of safe current is specifically as follows: ; In the formula, As the lower limit of safe current, and real-time current command , To balance the angle, For extreme logarithms, This represents the worst possible disruption that must be endured at every moment during the second phase. It is a permanent magnet flux linkage.

[0025] Furthermore, the aforementioned maximum current decrease rate is specifically as follows: ; In the formula, For the maximum current drop rate, This represents the maximum dynamically tolerable load step value. To reserve budget for actual external load step jumps, The natural frequency of the angular oscillation. It is a permanent magnet flux linkage. For extreme logarithms, For balance angle.

[0026] Furthermore, the switching condition mentioned above is that the misalignment angle converges to the allowable threshold.

[0027] Secondly, this application provides a margin-adaptive current reduction control system based on dynamic stability boundaries, applicable to any of the margin-adaptive current reduction control methods based on dynamic stability boundaries in the first aspect, including:

[0028] The model building module is used to build a sensorless motor basic model of the sliding mode observer, as well as to establish a dynamic model of the segmented operation and misalignment angle of If start-up;

[0029] The boundary solution module is used to obtain the dynamic stable boundary based on the motor's basic model and dynamic model, using the equal area criterion.

[0030] The current lower limit determination module is used to derive the safe current lower limit that minimizes dynamic constraints based on the dynamic stability boundary.

[0031] The execution module is used to solve the maximum allowable current drop rate at the current moment through the margin adaptive variable slope current reduction algorithm, and to execute based on the maximum current drop rate;

[0032] The switching module is used to stop the current from decreasing when it reaches the lower limit of the safe current, until the offset angle meets the switching conditions, preload the speed loop integrator to the end current command of the constant speed transition stage II, and smoothly switch to the closed-loop vector control of the sliding mode observer.

[0033] Thirdly, this application provides an electronic device, including: at least one processor, at least one memory, and a data bus;

[0034] In this system, the processor and memory communicate with each other via a data bus; the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the margin-based adaptive current reduction control method based on dynamic stability boundary, as described in any of the first aspects.

[0035] Fourthly, this application provides a non-transitory computer-readable storage medium that stores computer instructions that cause a computer to execute the margin-based adaptive current reduction control method based on dynamic stability boundaries as described in any of the first aspects.

[0036] Compared with the prior art, the present invention has at least the following beneficial effects:

[0037] 1. Quantify stability margin and solve the risk of step loss: This invention establishes a dynamic stability boundary through the equal area criterion, which is different from the traditional loose judgment standard that only relies on the static boundary. It derives the minimum safe current lower limit for all time periods. No matter the current reduction stage, it can resist the load step disturbance of the preset amplitude. The transient swing of the misalignment angle will not cross 0°, and completely avoid the motor step loss and shutdown caused by load fluctuation in the later stage of current reduction.

[0038] 2. Adaptive variable slope current reduction, balancing loss and stability: The current reduction rate is automatically adjusted according to the real-time recovery torque stiffness and remaining dynamic stability margin, forming a "fast reduction first, then slow reduction" curve; when the margin is sufficient, the stator current is reduced rapidly, significantly reducing copper loss during the transition phase; it automatically slows down when approaching the safety threshold, avoiding torque shock caused by sudden current drop, eliminating the need for manual segmented gain tuning, with fewer parameters and simpler debugging.

[0039] 3. Precise theoretical analysis, adaptable to all load conditions: The small-signal linearization model reveals the asymmetric sensitivity of the misalignment angle to load disturbances, and the stability margin can be accurately calculated for both light and heavy load conditions; it solves the stability risk caused by the amplification of the sliding mode observer error under light load, and is suitable for If start-up transition in the full load range;

[0040] 4. Smooth transition and minimal switching impact: The constraint current throughout the entire process is not lower than the dynamic safety lower limit, the misalignment angle converges smoothly, and the speed loop integrator is preloaded before switching FOC to eliminate instantaneous torque jump during switching, suppress torque pulsation, and improve the smoothness of motor operation.

[0041] 5. Strong robustness, no need for complex compensation loops: Compared with existing power compensation and multi-PI regulation schemes, this invention only relies on the basic dynamic equation of the motor to achieve adaptive regulation, without additional compensation loops, the controller structure is simple, and it is easy to implement in engineering on a digital DSP platform. Attached Figure Description

[0042] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0043] Figure 1 This is a flowchart illustrating the overall control block diagram for starting up in an embodiment of the present invention;

[0044] Figure 2 This is a schematic diagram of the starting segmented speed curve and the misalignment angle vector between the virtual / real rotor coordinate system in an embodiment of the present invention;

[0045] Figure 3 The above are surface plots and contour plots showing the steady-state misalignment offset as a function of the initial misalignment angle and load step in this embodiment of the invention.

[0046] Figure 4 This is a contour plot of the transient peak value of the misalignment angle in an embodiment of the present invention;

[0047] Figure 5 This is a comparison of the current decrease curve in stage II and the remaining stability margin curve in an embodiment of the present invention;

[0048] Figure 6 This is a simulation waveform of the transient response of the misalignment angle under a load step disturbance in an embodiment of the present invention;

[0049] Figure 7 This is a comparison of simulation waveforms for two control strategies under a 15% rated torque load disturbance in an embodiment of the present invention.

[0050] Figure 8 This is a flowchart of the control method in an embodiment of the present invention. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0052] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0053] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0054] In the description of the embodiments of the present invention, "multiple" means at least two.

[0055] Example 1: This example provides a margin-based adaptive current reduction control method based on dynamic stability boundaries, such as... Figure 8 As shown, the specific steps include the following:

[0056] S1. Construct a sensorless motor basic model for the sliding mode observer, and establish a dynamic model for segmented operation and misalignment angle during If start-up.

[0057] S2, based on the motor's basic model and dynamic model, obtains the dynamic stable boundary by solving based on the equal area criterion.

[0058] S3, based on the dynamic stability boundary, derive the lower limit of the safe current that minimizes the dynamic constraint.

[0059] S4 uses a margin-adaptive variable slope current reduction algorithm to solve for the maximum allowable current drop rate at the current moment, and executes the algorithm based on the maximum current drop rate.

[0060] S5, when the current reaches the lower limit of the safe current, it stops decreasing until the misalignment angle meets the switching condition, the speed loop integrator is preloaded to the end current command of stage II, and smoothly switched to the closed-loop vector control of the sliding mode observer.

[0061] Specifically, in all the reviewed methods, the second-stage reduction curve—linear, parabolic, or compensated—is heuristically designed and lacks any quantitative correlation with the stability margin of the driver at each moment during the ramp change process; as the current decreases, the bias angle decreases, and the self-stabilizing capability weakens; if the threshold is set too low, ordinary load fluctuations will lead to startup failure. This invention fills this gap through three innovative studies: First, the misalignment angle dynamics are linearized, revealing that the system has a significantly asymmetric, stiffness-dominated sensitivity to load disturbances; second, the dynamic stability boundary conditions obtained by the equal area analysis method are more stringent than the static boundary conditions, and a closed-loop minimum current threshold scheme is proposed to ensure stable operation of the system under specific worst-case load step conditions; finally, a margin-preserving adaptive deceleration law is proposed, which only consumes the remaining margin exceeding the preset budget range, thereby achieving the operating characteristics of fast startup and slow termination without gain scheduling.

[0062] Specifically, SENSORLESS focus control based on a sliding mode observer Figure 1 The overall structure of the studied drive device is shown in the figure. Figure 1 The internal current loop and space vector modulator are shared in both operating modes. During the If startup phase, the current reference value is applied to a virtual synchronous coordinate system, and its angle is obtained through an integral frequency command. After the switch is completed, the drive unit switches to sensorless FOC mode, in which the speed loop and coordinate transformation both use the rotor position and speed estimated by the SMO combined with the phase-locked loop (PLL). The monitoring module is responsible for scheduling each phase and implementing the deceleration law described in Section 4.

[0063] Among the existing sensorless methods, the back EMF SMO method is suitable for surface-mount permanent magnet synchronous motors (PMSMs) due to its high robustness and low parameter sensitivity. Therefore, this method is used for speed estimation.

[0064] In step S1 above, the basic motor model includes a steady state. The stator voltage equation, back electromotive force equation, and sliding mode observer model in the coordinate system are as follows: The stator voltage equation is: ,(1); The back electromotive force equation is: (2); The sliding mode observer model is as follows: (3); , (4); In the above formula, , , These represent the stator voltage charge, current vector, and back electromotive force vector, respectively. and These are the stator resistance and stator inductance, respectively. It is a permanent magnet flux chain. The angular velocity of the motor. Indicates the position of the motor rotor. This is an S-shaped switching function used to suppress oscillations. ; This indicates that the observer stability requires gain, and The parameter 'a' determines the steepness of the function near the zero point.

[0065] Specifically, see Figure 2 , Figure 2 (a) shows the reference speed curve during the standard If startup process. Figure 2 (b) shows the virtual rotor coordinate system and the actual rotor coordinate system, and the misalignment angle. The virtual q-axis lags behind the actual q-axis by an angle; the first stage covers the interval [0, t1]; in acceleration stage I, the q-axis current in the virtual coordinate system is constant, and the current ramps up at a given frequency, forming a self-stabilizing electromagnetic torque based on the offset angle, as expressed as: (5); In the formula, For electromagnetic torque, Since the number of pole pairs is constant, the reluctance term can be ignored for surface-mount motors. Represents the q-axis current. Indicates the misalignment angle. It is a permanent magnet flux linkage. , These represent the d-axis inductance and q-axis inductance, respectively. Self-stability requires hysteresis on the imaginary q-axis. >0): If the rotor decelerates as the load increases, then Decrease, cos The torque increases to restore synchronization, thus the first phase passes through... It adjusts itself to balance the negative torsional force.

[0066] In the constant-speed transition phase II, the given frequency remains constant, and the current reduction process begins. Based on the established second-order electromechanical equation of the misalignment angle, the transfer function from load disturbance to misalignment angle deviation is linearized. The misalignment angle can be used as a state variable, and the electromechanical behavior in the virtual coordinate system can be expressed as follows: (6); in For load torque, Let B be the moment of inertia and B be the coefficient of viscous friction. Substituting equation (5) into equation (6) yields the following information: Second-order nonlinear equations: (7); Under different load torques, equation (9) is a nonlinear time-varying system, and the equilibrium point in the constant speed stage is... At this point, the system satisfies: (8); in, The peak value of the torque-angle characteristic curve is given; linearizing equation (7) yields the transfer function from load torque disturbance to angle deviation: (9); , (10); in, To restore torque stiffness, The natural frequency of the angular oscillation, for the same load step... The responses at different equilibrium points differ significantly. Near heavy loads, the torque-angle curve flattens out at its peak, therefore K≈0: the deviation produces almost no corrective torque. Monotonic drift to an unstable state, Near the light load, the curve is steepest, K≈Tmax reaches its maximum value, and the system revolves around the new equilibrium point. Oscillation; due to the extremely small inherent damping in reality (B≈0), the oscillation persists and the peak offset is approximately twice the steady-state offset, but synchronization is maintained and the oscillation trajectory does not cross... .

[0067] See Figure 3 , Figure 3 This demonstrates the steady-state angle shift. and Load step amplitude In comparison, the sensitivity exhibits a significant asymmetry: when When near the target location, even with a large load step, the offset remains small; while when As the stiffness approaches zero, the system stiffness decreases sharply. like Figure 3 As shown by the outline of the cluster, the region is growing rapidly, and the drawn boundary defines the non-equilibrium region. Beyond this range, loss of synchronization becomes inevitable; therefore, the system startup phase is most vulnerable under small deviation angle conditions—this is precisely the state the second-stage optimization scheme deliberately guides the system to. The above analysis only covers the final equilibrium state change and does not address the transient fluctuations that actually determine the risk of loss of synchronization.

[0068] In step S2 above, when viscous damping is negligible, the If driving system is a conservative second-order system; and during the fluctuation period, its equation of motion is: ,(11) The equation contains an energy integral term, which occurs at the initial angle. and peak position When the kinetic energy is set to zero at all points, A step transition to the new load can be derived. Required equal area conditions: (12); By numerically solving equation (12), we obtain Thus, the peak swing amount is obtained. A conservative oscillator will surpass the equilibrium state by gaining energy from oscillating towards it; for small perturbations, this symmetry can be derived... This result has been numerically verified across the entire operating range; therefore, even a moderate steady-state shift will cause the transient peak value to double, and it is this peak value that determines whether the drive system leaves the stable region.

[0069] See Figure 4 , Figure 4 Showing Follow and A contour map showing changes, overlaid with two stability boundaries: the static limit (dashed line). Beyond this value, there is no equilibrium state; and the dynamic limit (solid line), as given by formula (12) Under the given conditions, it is concluded that when this value is exceeded, the oscillation process will deviate from the recoverable region, but the static equilibrium will still exist; as... The gap widens significantly as the dynamic safety zone decreases: the dynamic safety zone is much smaller than the static safety zone, especially in the early stages of high loads during the slope phase.

[0070] In step S3 above, according to formula (12). It is the minimum angle reached during the oscillation process after the disturbance, therefore dynamic survival requirements Consider the worst case in formula (12) Utilizing the balance relationship The operating point can be determined. The maximum dynamic load step value that can be withstanded is: (13); Can be set To set the worst possible interference that must be endured at every moment in the second phase, The minimum threshold can be obtained by solving for the current value. (14); At the angle of balance Below, able to withstand And there is no transient swing crossing. The minimum control instructions; a preliminary conservative protection measure is to constrain the conventional profile: (15); In the above, the clamping value can be calculated offline, but it is a conservative estimate: the reduction process only stops at the lower limit value, and the rate of decrease before stopping is independent of the instantaneous stability condition.

[0071] In step S4 above, the fastest rate that can still maintain dynamic margin has been derived for each control cycle; assuming that in The timing instructions are reduced at a constant rate; The system will occur in natural cycles The internal torque is insufficient to respond, therefore the cumulative current change over one cycle is: ,(16) Furthermore, it acts as an equivalent load step at the operating point: (17); In the formula, To reserve budget for actual external load step jumps, the ramp margin is set at: Furthermore, safety requirements stipulate that gaps caused by slopes must not exceed this margin (according to a coefficient). (<1 for scaling) , (18).

[0072] Combining equations (16)–(18), the proposed adaptive load reduction law can be derived: ,(19)

[0073] in Controlling aggression, this law allows for rate adjustment without scheduling or gain switching; with The decrease in equilibrium angle Decrease accordingly, thus shrinking This provides a controllable margin; however, the stiffness K will also decrease. The numerical decrease decreased This also extends the accumulation window of defects; the two mechanisms work together to form a characteristic curve of "rapid start and slow end": it decreases rapidly when the margin and stiffness are sufficient; it gradually slows down as the margin is consumed; and finally, the fixture forces the defects to reach the minimum level and stops. Figure 5 The proposed curves and linear curves, as well as the changing trends of their residual margins, were compared, which contrasts sharply with the fixed rate setting in the middle—the latter having no relation to the instantaneous stability conditions of the machine. Figure 5 The middle section compares the current decrease curve in Stage II with the remaining stability margin curve; among them, Figure 5 (a) shows the adaptive current reduction curve of this invention versus the traditional linear current reduction curve, with the lower limit of the dynamic minimum current marked; Figure 5 (b) Curves showing the change in the remaining dynamic stability margin throughout the entire process for both schemes.

[0074] Specifically, the algorithm's execution logic can be described as follows:

[0075] When the margin is sufficient and the stiffness is large, the current reduction rate is high, which quickly reduces the current and lowers the copper loss.

[0076] As the current decreases, the misalignment angle decreases, and the dynamic margin decays, the descent speed automatically slows down.

[0077] The current stops decreasing after it reaches the minimum safety lower limit until the offset angle meets the FOC switching condition.

[0078] In step S5 above, after the misalignment angle converges to the allowable threshold, the current command at the end of the preload stage II of the velocity loop integrator is smoothly switched to the sliding mode observer closed-loop vector control.

[0079] Specifically, this method can be theoretically verified using MATLAB simulation, and physical experiments can be conducted on a DSP digital control hardware platform. The algorithm code can be directly ported to mainstream motor control chips such as TI and ST, making engineering implementation easy. The core algorithm can be independently encapsulated as a control subroutine, compatible with the upgrading and transformation of existing sensorless drive systems using the If start mechanism. In specific implementation:

[0080] 1) Phase I Start-up: Given a constant q-axis rated current, the frequency ramps up to the observer's usable speed, and then Phase II begins;

[0081] 2) Activate the adaptive current reduction algorithm of this invention and collect the misalignment angle of the virtual coordinate system in real time. Substitute into equation (14) to calculate the real-time minimum safe current. ;

[0082] 3) Calculate the current maximum allowable current reduction rate using equation (19), update the q-axis current command in real time, and limit the current using equation (15). A 15% rated torque step load disturbance can be applied during the simulation.

[0083] During this process, the current reduction rate of the present invention automatically slows down with the remaining margin, the current is always higher than the safety lower limit, the minimum value of the misalignment angle is greater than 0°, there is no step loss, the speed is stable, and after the transition is completed, it smoothly switches to FOC closed-loop control.

[0084] The transient analysis results can also be verified: The motor is kept at a constant speed and a fixed current command is applied to stabilize the deflection angle at approximately 67°; after the transient process at startup has decayed, a load step equivalent to 8.3% of the rated torque is applied; For example... Figure 6 As shown, The value exhibited significant oscillations, initially dropping to approximately 56° before stabilizing around 62°; its peak swing was approximately 11°, 2.1 times the steady-state offset (approximately 5°), consistent with the equal-area prediction of 2.0. Despite the assumption that B is zero, the finite current loop bandwidth still produces a damping effect, explaining the eventual decay.

[0085] Secondly, the second-stage transition process of the linear load reduction scheme and the proposed strategy is compared under the same conditions: applying an equal amount of [missing information] during the later stage of slope ascent. A load step of 15% of rated torque; current already below the reference value when using a linear curve; oscillating drive. It will drop to zero, lose its self-stabilizing characteristics, and the startup process will end in continuous oscillation; however, when the proposed control law is used, the command never deviates from the reference value; the same disturbance only produces bounded oscillations ( The driver remains synchronized and then enters the conventional switching sequence of the preloaded speed loop integrator; both cases are as follows. Figure 7 As shown, the traditional linear current reduction waveform above exhibits out-of-step oscillations in the q-axis current, misalignment angle, and rotational speed waveforms; the proposed strategy below ensures that the current is stable above the safety lower limit, the misalignment angle does not cross zero, and the rotational speed is stable without out-of-step oscillations. The proposed strategy only moderately extends the ramp-up time, and the rapid start-up can compensate for the slow termination problem. At the same time, its structural design ensures robustness to specified disturbances.

[0086] Example 2: This application provides a margin-adaptive current reduction control system based on dynamic stability boundary, applied to the margin-adaptive current reduction control method based on dynamic stability boundary in Example 1, including:

[0087] The model building module is used to build a sensorless motor basic model of the sliding mode observer, as well as to establish a dynamic model of the segmented operation and misalignment angle of If start-up;

[0088] The boundary solution module is used to obtain the dynamic stable boundary based on the motor's basic model and dynamic model, using the equal area criterion.

[0089] The current lower limit determination module is used to derive the safe current lower limit that minimizes dynamic constraints based on the dynamic stability boundary.

[0090] The execution module is used to solve the maximum allowable current drop rate at the current moment through the margin adaptive variable slope current reduction algorithm, and to execute based on the maximum current drop rate;

[0091] The switching module is used to stop the current from decreasing when it reaches the lower limit of the safe current, until the offset angle meets the switching conditions, preload the speed loop integrator to the end current command of the constant speed transition stage II, and smoothly switch to the closed-loop vector control of the sliding mode observer.

[0092] Example 3: This application provides an electronic device, including: at least one processor, at least one memory, and a data bus;

[0093] In this system, the processor and memory communicate with each other via a data bus; the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the margin-adaptive current reduction control method based on dynamic stability boundary as described in Example 1.

[0094] Example 4: This application provides a non-transitory computer-readable storage medium that stores computer instructions that cause the computer to execute the margin-based adaptive current reduction control method based on dynamic stability boundary of Example 1.

[0095] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0096] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0097] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0098] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0099] Those skilled in the art will understand that all or part of the steps in the above facts and methods can be implemented by a program instructing related hardware. The program or the program described therein can be stored in a computer-readable storage medium. When the program is executed, it includes the following steps: at this time, the corresponding method steps are introduced. The storage medium can be ROM / RAM, magnetic disk, optical disk, etc.

[0100] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A margin-based adaptive current reduction control method based on dynamic stability boundary, characterized in that, The specific steps include the following: Construct a sensorless motor basic model for a sliding mode observer, and establish a dynamic model of segmented operation and misalignment angles for If start-up; Based on the motor basic model and the dynamic model, the dynamic stable boundary is obtained by solving based on the equal area criterion. Based on the dynamic stability boundary, derive the lower limit of the safe current with the minimum dynamic constraint. The maximum allowable current drop rate at the current moment is determined by the margin-adaptive variable slope current reduction algorithm, and the operation is performed based on the maximum current drop rate. When the current reaches the lower limit of the safe current, it stops decreasing until the misalignment angle meets the switching conditions. Then, the speed loop integrator is preloaded to the end current command of the constant speed transition stage II, and smoothly switched to the closed-loop vector control of the sliding mode observer.

2. The margin-based adaptive current reduction control method based on dynamic stability boundary as described in claim 1, characterized in that, The basic model of the motor includes a steady state. The stator voltage equation, back electromotive force equation, and sliding mode observer model in the coordinate system are as follows: The stator voltage equation is as follows: ; The back electromotive force equation is: ; The sliding mode observer model is as follows: ; ， ； In the above formula, , , These represent the stator voltage charge, current vector, and back electromotive force vector, respectively. and These are the stator resistance and stator inductance, respectively. It is a permanent magnet flux linkage. The angular velocity of the motor. Indicates the position of the motor rotor. This is an S-shaped switching function used to suppress oscillations. ; This indicates that the observer stability requires gain, and .

3. The margin-based adaptive current reduction control method based on dynamic stability boundary as described in claim 1, characterized in that, The If start-up includes an acceleration phase I and a constant-speed transition phase II; wherein: In the acceleration phase I, the current along the q-axis of the virtual coordinate system is constant, and the current ramps up at a given electrical frequency. A self-stabilizing electromagnetic torque is formed by the offset angle, expressed as: ； In the formula, For electromagnetic torque, For extreme logarithms, Represents the q-axis current. Indicates the misalignment angle. It is a permanent magnet flux linkage. , These represent the d-axis inductance and the q-axis inductance, respectively. In the constant-speed transition stage II, the given frequency remains constant, and the current reduction process begins. Based on the established second-order electromechanical equation of the misalignment angle, the transfer function from load disturbance to misalignment angle deviation is linearized and expressed as: ,in: ； In the formula, For load torque, For rotational inertia, Indicates the coefficient of viscous friction. This is the equilibrium point during the constant speed phase.

4. The margin-based adaptive current reduction control method based on dynamic stability boundary as described in claim 1, characterized in that, The dynamic stable boundary obtained based on the equal area criterion is as follows: Ignoring viscous friction, we establish the dynamic equations for rotor oscillation under disturbance, and derive the constant-area stability criterion using energy conservation: ； ； In the formula, For load torque, For rotational inertia, For extreme logarithms, Indicates the misalignment angle. For the load torque, when at the initial angle and peak position When the kinetic energy is set to zero at all points, A step transition to the new load can be derived. The required equal area condition.

5. The margin-based adaptive current reduction control method based on dynamic stability boundary as described in claim 1, characterized in that, The lower limit of the safe current is specifically as follows: ； In the formula, As the lower limit of safe current, and real-time current command , To balance the angle, For extreme logarithms, This represents the worst possible disruption that must be endured at every moment during the second phase. It is a permanent magnet flux linkage.

6. The margin-based adaptive current reduction control method based on dynamic stability boundary as described in claim 1, characterized in that, The maximum current decrease rate is specifically: ； In the formula, For the maximum current drop rate, This represents the maximum dynamically tolerable load step value. To reserve budget for actual external load step jumps, The natural frequency of the angular oscillation. It is a permanent magnet flux linkage. For extreme logarithms, For balance angle.

7. The margin-based adaptive current reduction control method based on dynamic stability boundary as described in claim 1, characterized in that, The switching condition is that the misalignment angle converges to an allowable threshold.

8. A margin-adaptive current reduction control system based on dynamic stability boundary, characterized in that, include: The model building module is used to build a sensorless motor basic model of the sliding mode observer, as well as to establish a dynamic model of the segmented operation and misalignment angle of If start-up; The boundary solution module is used to obtain the dynamic stable boundary based on the equal area criterion according to the motor basic model and the dynamic model. The current lower limit determination module is used to derive the safe current lower limit with the minimum dynamic constraint based on the dynamic stability boundary. The execution module is used to solve the maximum allowable current drop rate at the current moment through the margin adaptive variable slope current reduction algorithm, and to execute based on the maximum current drop rate; The switching module is used to stop decreasing the current when it reaches the lower limit of the safe current, until the offset angle meets the switching conditions, preload the speed loop integrator to the end current command of the constant speed transition stage II, and smoothly switch to the closed-loop vector control of the sliding mode observer.

9. An electronic device, characterized in that, include: At least one processor, at least one memory, and a data bus; The processor and the memory communicate with each other via the data bus. The memory stores program instructions that can be executed by the processor, which calls the program instructions to execute the margin-based adaptive current reduction control method based on dynamic stability boundary as described in any one of claims 1-7.

10. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium stores computer instructions that cause the computer to execute the margin-based adaptive current reduction control method based on dynamic stability boundaries as described in any one of claims 1-7.

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