A sensorless control method for permanent magnet synchronous motor based on a novel angle compensation strategy

Abstract

The application provides a sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy, establishes a current equation and a counter electromotive force equation according to structural parameters of a surface-mounted permanent magnet synchronous motor, and correlates and builds a counter electromotive force observer and a phase-locked loop to preliminarily estimate an angle, then maps the amplitude of a position error on a residual error of a decoupled d-axis voltage, constructs a variable step operator with sigmoid characteristics to dynamically schedule an optimization step, uses the step to inject a trial angle, establishes a compensation angle search algorithm based on a discrete parabolic optimization, extracts a corresponding voltage response signal to construct an optimization algorithm to obtain an optimal compensation angle that maximizes an estimated q-axis voltage, and provides a sensorless estimated angle compensation scheme that is applicable to various error factors, greatly increasing the stability and angle estimation accuracy of a sensorless control system for the permanent magnet synchronous motor.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet synchronous motor control technology, and in particular to a sensorless control method for permanent magnet synchronous motors based on a novel angle compensation strategy. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) have been widely used in industrial servo systems, new energy vehicles, and home appliances due to their high power density, high efficiency, and wide speed range. To reduce hardware costs and improve system reliability, sensorless control technology has become a research hotspot in modern AC drive technology. In the medium-to-high speed range, sensorless control strategies based on the motor's fundamental mathematical model and back EMF, such as sliding mode observers, model reference adaptive systems, and extended Kalman filters, are widely used for position estimation due to their excellent dynamic performance. In the low-speed range, high-frequency injection based on the motor's salient polarity is currently the mainstream approach.

[0003] Currently, with the development of power electronics technology and control theory, permanent magnet synchronous motors (PMSMs) are increasingly widely used. However, to achieve high-performance PMSM control, accurate rotor position and speed information is required. The installation and use of mechanical sensors increases system cost, size, and weight, and imposes strict requirements on the operating environment. Sensorless control technology, by detecting relevant electrical signals in the motor windings and employing specific control algorithms, estimates rotor position and speed, representing a development trend in PMSM control systems. In many practical applications, sensorless control of PMSMs is affected by various error factors, such as inverter dead zone, inherent parameter offsets caused by temperature fluctuations, and digital calculation delays. Under the influence of these factors, the angle estimation accuracy of sensorless control suffers significant damage. Therefore, designing a universal angle compensation scheme that can compensate for multiple error factors is essential. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] In view of the aforementioned existing problems, the present invention is proposed.

[0006] Therefore, the present invention provides a sensorless control method for permanent magnet synchronous motors based on a novel angle compensation strategy, which can solve the problems mentioned in the background art.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy, comprising:

[0008] Based on the structural parameters and internal parameters of the surface-mounted permanent magnet synchronous motor, the current equation and back electromotive force equation of the surface-mounted permanent magnet synchronous motor in the stationary coordinate system and the rotating coordinate system are established.

[0009] Combining the current equation and the back electromotive force equation, an initial angle estimation module is built. An observer is used to observe the back electromotive force, and a phase-locked loop is used to solve the observed back electromotive force to initially calculate the rotor angle and speed.

[0010] Since minimizing the estimated angle error requires maximizing the estimated q-axis voltage, a compensation angle search algorithm is designed based on discrete parabolic optimization to find the compensation angle that maximizes the estimated q-axis voltage. The magnitude of the position error is mapped by extracting the decoupled d-axis voltage residual, and a variable step-size operator with sigmoid properties is constructed to dynamically schedule the optimization step size. This step size is then used to inject trial angles, and the corresponding voltage response signal is extracted to construct a parabolic optimization algorithm to find the optimal compensation angle that maximizes the estimated q-axis voltage. This compensation angle is then used to complete the final angle estimation.

[0011] As a preferred embodiment of the sensorless control method for permanent magnet synchronous motors based on a novel angle compensation strategy described in this invention, it further includes:

[0012] The current equation and back electromotive force equation represent the electrical relationship between rotor angle, velocity, and current in the stationary and rotating coordinate systems, respectively.

[0013] The initial angle calculation module includes a back EMF observer and an adaptive phase-locked loop, used to perform preliminary angle and rotational speed calculations before angle compensation;

[0014] The proposed compensation angle search algorithm based on discrete parabolic optimization includes an adaptive operator that maps the decoupled d-axis voltage residual to a sigmoid function and an optimal compensation angle calculation strategy based on discrete parabolic optimization. These are used to provide an adaptive iteration step size for discrete parabolic optimization and to calculate the optimal angle compensation value, respectively.

[0015] As a preferred embodiment of the sensorless control method for permanent magnet synchronous motors based on a novel angle compensation strategy described in this invention, the step of establishing the current equation and back electromotive force equation of the surface-mounted permanent magnet synchronous motor in the stationary coordinate system and the rotating coordinate system according to the structural parameters and internal parameters of the motor includes:

[0016] The voltage equation of a permanent magnet synchronous motor in the α-β axis coordinate system can be expressed as:

[0017]

[0018] Among them, u α Let u be the voltage along the α-axis. β For β-axis voltage; i α Let i be the α-axis current. β For β-axis current; L s It is the stator inductance, L in a surface-mounted permanent magnet synchronous motor. d =L q ;R s It is the stator resistance of the motor; e α e β These are the back electromotive forces along the α-axis and β-axis, respectively.

[0019] The back electromotive force equation of a permanent magnet synchronous motor in the α-β axis coordinate system can be expressed as:

[0020]

[0021] Where, ω e It is the motor speed, ψ f It is the stator flux linkage, θ e This refers to the rotor position.

[0022] As a sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy, as described in this invention, the method includes: constructing an initial angle estimation module by combining the current equation and the back electromotive force equation; using an observer to observe the back electromotive force and using a phase-locked loop to solve the observed back electromotive force; and initially calculating the rotor angle and speed, including:

[0023] The voltage equations for the surface-mount motor are reconstructed and rewritten as standard first-order ordinary differential state equations with stator current as the state variable, as shown below:

[0024]

[0025] Where p represents the differential operator.

[0026] Based on the state reconstruction concept in control theory, a corresponding full-dimensional state observer is constructed within a digital controller. Observed state variables are introduced, and a feedback compensation matrix is ​​designed to ensure observer convergence.

[0027]

[0028] in, It estimates the current U in the coordinate system. comp It is the equivalent variable of the state observer.

[0029] Subtracting the two equations above, we obtain the error equation for the current as follows:

[0030]

[0031] in It is the difference between the estimated value and the actual value of the current.

[0032] In order for the observed current to gradually track the actual current, a reasonable feedback law must be designed. This ensures that the above error system satisfies strict Lyapunov stability. When the system reaches a stable convergent state under the action of the feedback law, the error will approach zero relative to its corresponding differential component. Therefore, we can conclude that:

[0033]

[0034] Therefore, the analytical expression for the reconstruction of the back electromotive force can be derived:

[0035]

[0036] Since practical digital control systems often contain high-frequency switching noise or discrete quantization steps, an equivalent low-pass filter (LPF) is needed to filter the underlying back electromotive force in order to extract a smooth fundamental back electromotive force.

[0037]

[0038] Among them, G LPF (s) represents the transfer function of the filter.

[0039] The amplitude of the back electromotive force changes drastically with the rotational speed. Directly using the arctangent function to solve for the angle will cause pole divergence at the zero-crossing point and will severely amplify high-frequency noise. Therefore, this system uses a quadrature phase-locked loop to extract the angle in the closed loop.

[0040] Based on the obtained back electromotive force, construct the phase error components:

[0041]

[0042] Substituting the extended theoretical fundamental model of the back electromotive force into this equation, we obtain:

[0043]

[0044] Among them, E ext To extend the back electromotive force.

[0045] When the estimated angle is close to the true angle, the angle error is small, allowing for a linear approximation. After normalization, the error signal can be obtained:

[0046]

[0047] The error signal is filtered by a PI interlocked filter to obtain a stable estimate of the electrical angular velocity. Integrating this value yields the estimated rotor position, thus completing the closed-loop logic of the entire back EMF observer.

[0048] As a preferred embodiment of the sensorless control method for permanent magnet synchronous motors based on a novel angle compensation strategy described in this invention, the method includes: designing a compensation angle search algorithm based on discrete parabolic optimization, mapping the magnitude of the position error by extracting the decoupled d-axis voltage residual, and constructing a variable step-size operator with sigmoid characteristics to dynamically schedule the optimization step size, including:

[0049] When using parabolic optimization algorithms, the choice of iteration step size is crucial. A larger step size accelerates the convergence speed but can induce severe oscillations near the optimum. A smaller step size reduces system oscillations but results in slower optimization and susceptibility to fixed noise when applied to motor control systems, making it difficult to find the optimum. Therefore, this invention proposes a nonlinear adaptive step size scheduling method based on d-axis voltage residuals.

[0050] Assume the voltage residual is:

[0051]

[0052] Where ε e It is the voltage residual, which can be seen from the above formula as ε e This can represent the degree of deviation in the current angle. To achieve stable searching in the small error region and rapid iteration in the large error region, this invention designs a nonlinear step-size mapping based on the sigmoid function, and the adaptive step-size update rule is expressed as follows:

[0053]

[0054] Where, Δθ max Δθ represents the maximum allowed injection angle limit of the algorithm. max This represents the minimum allowable injection angle limit allowed by the algorithm, c is the center point of the soft dead zone used to mask inherent hardware noise, a is the gain slope, and the negative compensation term... This is the deviation correction amount.

[0055] As a preferred embodiment of the sensorless control method for permanent magnet synchronous motors based on a novel angle compensation strategy described in this invention, the method includes: injecting trial angles using the adaptive step size, extracting the corresponding voltage response signal, constructing a parabolic optimization algorithm to find the optimal compensation angle that maximizes the estimated q-axis voltage, including:

[0056] Since for any unknown nonlinear objective function y = f(x) with second-order continuous derivatives, it is assumed that there exists a unique extremum point within a local interval. According to the principles of calculus, a local second-order Taylor expansion can be performed in the neighborhood of any point of this function:

[0057]

[0058] Near the extreme point, higher-order truncation errors decay rapidly, and the local geometry of the objective function degenerates into a standard quadratic parabola. To solve the extreme point problem without an analytical expression for the objective function, the idea of ​​discrete sampling is introduced. Taking the current point x... k Centered on the sample, a symmetrical perturbation step size h is applied to obtain three equally spaced sampling points: the left point x l =x k -h, center point x c =x k Point x on the right r =x k +h.

[0059] After obtaining the corresponding function response value y l y c y r Then, the first derivative and second curvature at that point can be precisely estimated numerically using the central difference method:

[0060]

[0061] Since the derivative at the extreme point is zero, the optimization compensation amount should satisfy the following in this local parabolic model:

[0062] f′(x k )+f″(x k )Δx opt =0

[0063] Substituting the difference estimation formula into the equation above, we obtain the classic parabolic extremum analysis compensation formula:

[0064]

[0065] By mapping the physical quantities in the motor control system to the adaptive step size calculation formula, substituting the specific physical quantities, and using the McLaurin series expansion of the cosine function within the limit range where the error angle approaches zero, we can obtain:

[0066]

[0067] As can be seen from the above equation, near the steady-state point, the estimated q-axis voltage curve is roughly equivalent to a downward-opening second-order parabola. If we map the test angle to the above parabolic optimization process, and assume the optimization step size is dθ, then θ... l Indicates the test angle on the left, θ c It is the intermediate test angle, θ r It is the test angle on the right, θ comp The optimal compensation angle was calculated in the previous optimization cycle, and k represents the current moment. Therefore, the detection angle is set as follows:

[0068]

[0069] The aforementioned angle command is input into the control system, and the corresponding estimated q-axis voltage response is extracted. Then, these values ​​are substituted into the aforementioned parabolic formula to calculate the current optimal position compensation angle:

[0070]

[0071] The calculated compensation angle is fed back to the position controller to correct the current position detected by the phase-locked loop, thus obtaining the final estimated angle:

[0072]

[0073] A sensorless control method for permanent magnet synchronous motors based on a novel angle compensation strategy includes a model establishment module, a preliminary angle calculation module, and an angle compensation module.

[0074] The model building module is used to establish and correlate the current equation and back electromotive force equation of the surface-mounted permanent magnet synchronous motor in the stationary coordinate system (α-β axis) based on the structural parameters and internal parameters of the motor.

[0075] An angle preliminary calculation module is used to build a back EMF observer and a phase-locked loop based on the aforementioned mathematical model, and to preliminarily estimate the rotor electrical angle and speed.

[0076] An angle compensation module is used to construct a nonlinear adaptive step size by combining the sigmoid function mapping. Based on this step size, a compensation angle search algorithm based on discrete parabolic optimization is established. On the basis of the angle calculation module of traditional back EMF observer and phase-locked loop, the compensation angle is calculated. The compensation angle is summed with the angle obtained from the preliminary calculation to obtain the final estimated angle.

[0077] The beneficial effects of this invention are as follows: This invention proposes a sensorless control method for permanent magnet synchronous motors based on a novel angle compensation strategy. Based on the structural parameters and internal parameters of the surface-mounted permanent magnet synchronous motor, the current equation and back electromotive force (EMF) equation of the surface-mounted permanent magnet synchronous motor are established in both the stationary and rotating coordinate systems. Combining these equations, an initial angle estimation module is built. An observer is used to observe the back EMF, and a phase-locked loop (PLL) is used to solve the observed back EMF, initially calculating the rotor angle and speed. A compensation angle search algorithm is designed based on discrete parabolic optimization. The magnitude of the position error is mapped by extracting the decoupled d-axis voltage residual, and a variable step-size operator with sigmoid characteristics is constructed to dynamically schedule the optimization step size. This step size is then used to inject trial angles, and the corresponding voltage response signal is extracted to construct a parabolic optimization algorithm to find the optimal compensation angle that maximizes the estimated q-axis voltage. This provides a sensorless angle estimation compensation scheme that is applicable under various error influences, greatly increasing the accuracy of sensorless control and angle calculation precision of permanent magnet synchronous motors. Attached Figure Description

[0078] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0079] Figure 1 The overall control block diagram of a sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy is provided in one embodiment of the present invention.

[0080] Figure 2 A diagram showing the relationship between the actual rotating coordinate system and the estimated rotating coordinate system in a sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy, provided as an embodiment of the present invention.

[0081] Figure 3-4 A comparison chart of rotor electric angle estimation performance in a simulation environment using a novel angle compensation strategy and a traditional angle estimation strategy, provided as an embodiment of the present invention;

[0082] Figure 5-6 This is a comparison chart showing the rotor electrical angle estimation performance under experimental conditions using a novel angle compensation strategy and a traditional angle estimation strategy, as provided in an embodiment of the present invention. Detailed Implementation

[0083] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0084] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0085] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0086] This invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0087] Furthermore, in the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0088] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0089] Example 1

[0090] Reference Figure 1-2This is the first embodiment of the present invention, which provides a sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy, comprising:

[0091] Based on the structural parameters and internal parameters of the surface-mounted permanent magnet synchronous motor, the current equation and back electromotive force equation of the surface-mounted permanent magnet synchronous motor in the stationary coordinate system and the rotating coordinate system are established.

[0092] The voltage equation of a permanent magnet synchronous motor in the α-β axis coordinate system can be expressed as:

[0093]

[0094] Among them, u α Let u be the voltage along the α-axis. β For β-axis voltage; i α Let i be the α-axis current. β For β-axis current; L s It is the stator inductance, L in a surface-mounted permanent magnet synchronous motor. d =L q ;R s It is the stator resistance of the motor; e α e β These are the back electromotive forces along the α-axis and β-axis, respectively.

[0095] The back electromotive force equation of a permanent magnet synchronous motor in the α-β axis coordinate system can be expressed as:

[0096]

[0097] Where, ω e It is the motor speed, ψ f It is the stator flux linkage, θ e This refers to the rotor position.

[0098] Based on the voltage equation, its differential equation is written with current as the state variable. The current state is reconstructed in the estimated coordinate system, and the two equations are subtracted to obtain the error equation of the current:

[0099]

[0100] in It is the difference between the estimated value and the actual value of the current.

[0101] A back EMF observer is constructed based on the error equation, and the phase error component is constructed based on the observed back EMF:

[0102]

[0103] By feeding the error component into a quadrature phase-locked loop and performing normalization and other processing, the error signal can be obtained:

[0104]

[0105] The error signal is filtered through a PI interlocked filter to obtain a stable estimate of the electrical angular velocity. Integrating this value yields the estimated rotor position, thus completing the preliminary estimation of the rotor position.

[0106] Furthermore, a compensation angle search algorithm based on discrete parabolic optimization is designed. The magnitude of the position error is mapped by extracting the decoupled d-axis voltage residual, and a variable step size operator with sigmoid characteristics is constructed to dynamically schedule the optimization step size. The step size is then used to inject trial angles, and the corresponding voltage response signal is extracted to construct a parabolic optimization algorithm to find the optimal compensation angle that maximizes the estimated q-axis voltage.

[0107] Assume the voltage residual is:

[0108]

[0109] Where ε e It is the voltage residual, which can be seen from the above formula as ε e This can represent the degree of deviation in the current angle. To achieve stable searching in the small error region and rapid iteration in the large error region, this invention designs a nonlinear step-size mapping based on the sigmoid function, and the adaptive step-size update rule is expressed as follows:

[0110]

[0111] Where, Δθ max Δθ represents the maximum allowed injection angle limit of the algorithm. min This represents the minimum allowable injection angle limit allowed by the algorithm, c is the center point of the soft dead zone used to mask inherent hardware noise, a is the gain slope, and the negative compensation term... This is the deviation correction amount.

[0112] Let the optimization step size be dθ, θ l Indicates the test angle on the left, θ c It is the intermediate test angle, θ r It is the test angle on the right, θ comp The optimal compensation angle was calculated in the previous optimization cycle, and k represents the current moment. Therefore, the detection angle is set as follows:

[0113]

[0114] The aforementioned angle command is input into the control system, and the corresponding estimated q-axis voltage response is extracted. Then, these values ​​are substituted into the aforementioned parabolic formula to calculate the current optimal position compensation angle:

[0115]

[0116] The calculated compensation angle is fed back to the position controller to correct the current position detected by the phase-locked loop, thus obtaining the final estimated angle:

[0117]

[0118] It should be noted that, depending on the specific circumstances of the motor and the application scenario, the parameters of the motor controller and the observer need to be adjusted. For example, the proportional, integral, and derivative coefficients of the PID controller, and the gain of the observer, etc., need to be adjusted to ensure the stability of the control system.

[0119] It should be noted that after completing the initial estimation of motor speed and angle, the maximum allowable injection angle limit Δθ should be reasonably set when establishing the angle compensation module. max Minimum allowable injection angle limit Δθ min , center point c, gain slope a.

[0120] It should be noted that before calculating the compensation angle, a second-order curvature evaluation of the parabola equation established at the current sampling point is required to ensure that the parabola equation used for calculation opens downwards.

[0121] In the embodiments of this application, Figure 1 This is an overall block diagram of the sensorless control system based on novel angle compensation described in this invention. Figure 2 This is a diagram showing the relationship between the estimated coordinate system and the actual coordinate system in the algorithm described in this invention.

[0122] It should be noted that by combining nonlinear adaptive step size with angle compensation algorithm, the impact of various irrational error factors on the angle estimation accuracy of motor sensorless control is effectively reduced, greatly enhancing the stability and accuracy of motor sensorless control under various operating conditions.

[0123] Example 2

[0124] Reference Figure 3-4 This is the second embodiment of the present invention, which provides a sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy. To verify the beneficial effects of the present invention, a simulation comparison experiment is conducted for scientific demonstration.

[0125] In this embodiment, a traditional sliding mode observer is selected for comparative testing. The simulation test results are compared using scientific verification methods to verify the real effect of this method.

[0126] For comparative simulation, the following parameters of the permanent magnet synchronous motor are used in this implementation:

[0127] The motor has a power of 0.1kW, a rated voltage of 48V, a rated current of 5.7A, a rated speed of 3000r / min, a rated torque of 0.64N·m, and a moment of inertia of 0.0000175kg·m. 2 Resistance 0.3Ω, inductance 1.378mH, flux linkage 0.0181Wb.

[0128] The formula for the traditional sliding mode observer, used as a comparison, is:

[0129]

[0130] in This is the convergence rate.

[0131] For a traditional sliding mode observer + traditional phase-locked loop, the sliding mode gain is k = 200, and the PI gain of the phase-locked loop is k. p =80, k i =10; For the method of the present invention, the maximum permissible injection angle is limited to Δθ. max =0.4, minimum allowable injection angle limit Δθ min =0.05, center point c=1.5, gain slope a=1. The method of this invention was compared with the traditional sliding mode observer + traditional phase-locked loop method, with the rotational speed set at 1000 r / min. (Refer to...) Figure 3 and Figure 4 It can be seen that without the addition of the compensation algorithm, the observation error of the rotor electrical angle is about 0.2 rad, while after adding the angle compensation algorithm described in this invention, the rotor electrical angle error is reduced to about 0.019 rad. It can be seen that under the action of this invention, the angle observation error of the sensorless motor control is reduced by 0.18 rad, which significantly improves the angle estimation accuracy of the sensorless motor control system.

[0132] Example 3

[0133] Reference Figure 5-6 This is the third embodiment of the present invention, which provides a sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy. To verify the beneficial effects of the present invention, a comparative experiment is conducted for scientific demonstration.

[0134] In this embodiment, a traditional sliding mode observer is selected for comparative testing. The experimental results are compared using scientific methods to verify the actual effectiveness of the proposed method.

[0135] The inherent parameters such as motor parameters and observer gain used in this comparative experiment are the same as those described previously.

[0136] Reference Figure 5 and Figure 6It can be seen that without the addition of the compensation algorithm, the estimation error of the rotor electrical angle is about 0.16 rad, while after adding the angle compensation algorithm described in this invention, the rotor electrical angle error is reduced to about 0.05 rad. It can be seen that under the action of this invention, the angle observation error of the sensorless control of the motor is reduced by 0.11 rad, which significantly improves the angle estimation accuracy of the sensorless control system of the motor and greatly enhances the stability and accuracy of the motor under the action of different non-ideal error factors.

[0137] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy, characterized in that, include: Based on the structural parameters of the surface-mounted permanent magnet synchronous motor, the current equation and the back electromotive force equation are established and correlated. Combining the current equation and the back electromotive force equation, a back electromotive force observer and a phase-locked loop are constructed to perform preliminary angle estimation. The magnitude of the position error is mapped by extracting the decoupled d-axis voltage residual, and a system with si is constructed. gm The variable step size operator with oid characteristics dynamically schedules the optimization step size; Using this step size, an experimental angle injection is performed, and a compensation angle search algorithm based on discrete parabolic optimization is established. The corresponding voltage response signal is extracted to construct an optimization algorithm to find the optimal compensation angle.

2. The sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy as described in claim 1, characterized in that, Also includes: The current equation and back electromotive force equation represent the relationship between the rotor angle, velocity, and current in the α-β axis direction in the stationary coordinate system (α-β axis). The nonlinear adaptive step size is used to balance the contradiction between the optimization speed far from the optimal point and the steady-state oscillation near the optimal point; The angle compensation algorithm is based on minimizing the estimated angle error by maximizing the estimated q-axis voltage.

3. The sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy as described in claim 2, characterized in that, The process of establishing and correlating the current equations and back electromotive force equations of the surface-mounted permanent magnet synchronous motor in the stationary coordinate system (α-β axis) includes: The voltage equation of a permanent magnet synchronous motor in the α-β axis coordinate system can be expressed as: Among them, u α Let u be the voltage along the α-axis. β For β-axis voltage; i α Let i be the α-axis current. β For β-axis current; L s It is the stator inductance, L in a surface-mounted permanent magnet synchronous motor. d =L q ;R s It is the stator resistance of the motor; e α e β These are the back electromotive forces along the α-axis and β-axis, respectively. The back electromotive force equation of a permanent magnet synchronous motor in the α-β axis coordinate system can be expressed as: Where, ω e It is the motor speed, ψ f It is the stator flux linkage, θ e This refers to the rotor position.

4. The sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy as described in claim 3, characterized in that, Combining the voltage equation and the back electromotive force equation, the current state equation is constructed, including: The voltage equations for the surface-mount motor are reconstructed and rewritten as standard first-order ordinary differential state equations with stator current as the state variable, as shown below: Where p represents the differential operator. A corresponding full-dimensional state observer was constructed within the digital controller. The observed state variables were introduced, and a feedback compensation matrix was designed to ensure observer convergence. in, It estimates the current U in the coordinate system. comp It is the equivalent variable of the state observer. Subtracting the two equations above, we obtain the error equation for the current as follows: in It is the difference between the estimated value and the actual value of the current.

5. The sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy as described in claim 4, characterized in that, Design a back EMF observer based on the current error equation, including: Derive the analytical expression for the reconstruction of the back electromotive force: Filter it using an equivalent low-pass filter (LPF): Among them, G LPF (s) represents the transfer function of the filter. Based on the obtained back electromotive force, construct the phase error components: When the estimated angle is close to the true angle, the angle error is small, allowing for a linear approximation. After normalization, the error signal can be obtained: The error signal is filtered by a PI interlocking filter to obtain a stable estimate of the electrical angular velocity. Integrating this value yields the estimated rotor position, completing the preliminary estimation of the rotor angle and velocity.

6. The sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy as described in claim 5, characterized in that, Based on the decoupled d-axis voltage residual, a nonlinear adaptive step size with sigmoid characteristics is designed, including: Assume the voltage residual is: It can be seen that ε e This can represent the degree of deviation in the current angle. Combining the characteristics of the sigmoid function, the adaptive step size update rule is expressed as follows: Where, Δθ max Δθ represents the maximum allowed injection angle limit of the algorithm. max This represents the minimum allowable injection angle limit of the algorithm, c is the center point of the soft dead zone used to mask inherent hardware noise, a is the gain slope, and the negative compensation term. It is the deviation correction amount.

7. The sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy as described in claim 6, characterized in that, Based on the calculated nonlinear adaptive step size, a compensation angle search algorithm is constructed. This algorithm is based on the theory that the direction that minimizes the estimated angle error is the direction that maximizes the estimated q-axis voltage, and includes: Assume the optimization step size is dθ, θ l Indicates the test angle on the left, θ c It is the intermediate test angle, θ r It is the test angle on the right, θ comp The optimal compensation angle was calculated in the previous optimization cycle, and k represents the current moment. Based on the parabolic optimization principle, the trial angle is set as follows: The aforementioned angle command is input into the control system, and the corresponding estimated q-axis voltage response is extracted. Then, these values ​​are substituted into the aforementioned parabolic formula to calculate the current optimal position compensation angle:

8. The sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy as described in claim 7, characterized in that: The calculated compensation angle is fed back to the position controller to correct the current position detected by the phase-locked loop, thus obtaining the final estimated angle:

9. The sensorless control method for a permanent magnet synchronous motor based on a novel angle compensation strategy as described in claim 8, characterized in that: Before calculating the compensation angle, a second-order curvature evaluation needs to be performed on the parabolic equation established at the current sampling point to ensure that the parabolic equation used for calculation opens downwards.

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