Non-electrolytic capacitor permanent magnet motor control method and system based on non-linear observer

Abstract

The invention discloses a non-electrolytic capacitor permanent magnet motor control method and system based on a non-linear observer, and the method comprises the steps: introducing a gradient search mechanism based on a stator voltage equation of a permanent magnet synchronous motor under a static coordinate system, and constructing a flux linkage observer equation; acquiring a voltage component and a current component of the permanent magnet synchronous motor in a static coordinate system, and observing the flux linkage observer equation to obtain a real component of a flux linkage amplitude error in a rotating coordinate system; and designing an exponential reaching law adaptive law, introducing an exponential reaching law to dynamically adjust the gradient search gain, and combining the real component of the flux linkage amplitude error under the rotating coordinate system as feedback to obtain the rotor position of the permanent magnet synchronous motor. The estimated flux linkage error value is used as the feedback quantity, and the real position of the rotor of the permanent magnet synchronous motor can be quickly and accurately tracked. The non-electrolytic capacitor permanent magnet motor control method and system based on the non-linear observer can be widely applied to the technical field of permanent magnet motor control.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of permanent magnet motor control, and particularly relates to a control method and system for a permanent magnet motor without electrolytic capacitor based on a nonlinear observer. BACKGROUND

[0002] Permanent magnet synchronous motor (PMSM) is widely used in electric vehicles, industrial drives and home appliances (such as air conditioner compressors) due to its high power density, high efficiency and high dynamic performance. Traditional PMSM control relies on mechanical sensors (such as encoders) to obtain rotor position, but has the following problems:

[0003] 1) High cost: high-precision encoders are expensive, increasing system cost.

[0004] 2) Low reliability: sensors are susceptible to electromagnetic interference (EMI), mechanical vibration and temperature, leading to failure.

[0005] 3) Installation restrictions: sensors cannot be installed in some situations (such as sealed compressors).

[0006] Therefore, sensorless control becomes a key technology, which is to estimate rotor position through motor mathematical model and electrical signals (voltage, current) instead of physical sensors. In sensorless control, the method based on flux linkage observation is the mainstream solution in low-speed scenarios due to its simple structure and no need for high-frequency signal injection. The core idea is to estimate the stator flux linkage by integrating the motor voltage equation, and then calculate the rotor position. However, the pure integrator has DC bias and initial value error problems, leading to divergence of flux linkage estimation. In the driving scheme without electrolytic capacitor, the bus voltage fluctuates in a large range, causing great disturbance to position observation. In the prior art, a nonlinear flux observer is proposed and has strong practicability, which is to correct the DC bias problem of the integrator through the flux linkage amplitude error feedback term, but its core problem is the lack of dynamic adaptability, which is specifically manifested as: when the position error is too large, there is slow convergence speed and unreasonable convergence trajectory, leading to insufficient stability in low-speed working conditions, and large observation position error when external disturbances such as bus voltage fluctuation exist. SUMMARY

[0007] To solve the above technical problems, the purpose of the present application is to provide a control method and system for a permanent magnet motor without electrolytic capacitor based on a nonlinear observer, which can quickly and accurately track the real position of the rotor of the permanent magnet synchronous motor by using the estimated flux linkage error value as the feedback quantity.

[0008] The first technical solution adopted by the present application is: a control method for a permanent magnet motor without electrolytic capacitor based on a nonlinear observer, comprising the following steps:

[0009] Based on the stator voltage equation of the permanent magnet synchronous motor in the stationary coordinate system, a gradient search mechanism is introduced to construct the flux linkage observer equation.

[0010] The voltage component and the current component of the permanent magnet synchronous motor in the stationary coordinate system are obtained, and the real part of the flux linkage amplitude error in the rotating coordinate system is obtained by observing the flux linkage observer equation.

[0011] An exponential approach law adaptive law is designed, the exponential approach law is introduced to dynamically adjust the gradient search gain, and the real part of the flux linkage amplitude error in the rotating coordinate system is combined as feedback to obtain the rotor position of the permanent magnet synchronous motor.

[0012] Further, the step of constructing the flux linkage observer equation based on the stator voltage equation of the permanent magnet synchronous motor in the stationary coordinate system, specifically includes:

[0013] Obtain the stator voltage equation of the permanent magnet synchronous motor in the stationary coordinate system;

[0014] Transform the stator voltage equation to construct the dynamic equation of the flux linkage;

[0015] Introduce the gradient search mechanism, correct the dynamic equation of the flux linkage by the error feedback of the integrator to construct the flux linkage observer equation.

[0016] Further, the expression of the flux linkage observer equation is specifically as follows:

[0017]

[0018] In the above formula, represents the flux linkage observer equation, v αβ represents the component of the motor terminal voltage in the stationary coordinate system (αβ axis), R s represents the stator winding resistance, i αβ represents the component of the motor stator current in the stationary coordinate system (αβ axis), λ represents the adjustment coefficient of the gradient search mechanism, represents the rotor flux linkage estimation value, k represents the gradient search gain, represents the quadrature flux linkage vector, ψ e represents the rated amplitude of the permanent magnet flux linkage.

[0019] Further, the step of obtaining the voltage component and the current component of the permanent magnet synchronous motor in the stationary coordinate system, and observing the flux linkage observer equation to obtain the real part of the flux linkage amplitude error in the rotating coordinate system, specifically includes:

[0020] The voltage component and the current component of the permanent magnet synchronous motor in the stationary coordinate system are obtained;

[0021] Based on the voltage component and the current component of the permanent magnet synchronous motor in the stationary coordinate system, the stator flux linkage estimation value to be updated is obtained according to a flux linkage observer equation;

[0022] The stator flux linkage estimation value to be updated is updated by numerical integration, and the stator flux linkage estimation value is obtained;

[0023] Based on the voltage component and the current component of the permanent magnet synchronous motor in the stationary coordinate system, the stator flux linkage estimation value to be updated is obtained according to a flux linkage observer equation;

[0024] The stator flux linkage estimation value to be updated is updated by numerical integration, and the stator flux linkage estimation value is obtained;

[0025] The stator flux linkage estimation value to be updated is updated by numerical integration, and the stator flux linkage estimation value is obtained;

[0026] Further, the expression for updating the stator flux linkage estimation value to be updated is specifically as follows:

[0027]

[0028] In the above formula, represents the stator flux linkage estimation value, represents the flux linkage observer equation, t represents the current time, and Δt represents the sampling period of the discrete time system.

[0029] Further, the calculation expression of the approximate stator flux linkage value is specifically as follows:

[0030]

[0031] In the above formula, ψ s represents the approximate stator flux linkage value, ω c represents the low-pass filter coefficient of the flux linkage, s represents the Laplace operator, v αβ represents the component of the motor terminal voltage in the stationary coordinate system (αβ axis), R s represents the stator winding resistance, i αβ represents the component of the motor stator current in the stationary coordinate system (αβ axis).

[0032] Further, the calculation expression of the real part of the flux linkage amplitude error in the rotating coordinate system is specifically as follows:

[0033]

[0034] In the above formula, χ2 represents the real part of the flux linkage amplitude error in the rotating coordinate system, ψ erepresents a rated amplitude of a magnetic flux linkage of a permanent magnet, represents a magnetic flux linkage error value in a stationary coordinate system, θ e represents an actual position of a motor rotor, represents an estimated value of a rotor position, represents a rotation factor constructed based on the estimated rotor position.

[0035] Further, the design exponential approach law adaptive law introduces an exponential approach law to dynamically adjust the gradient search gain and combines the real part of the magnetic flux amplitude error in the rotating coordinate system as feedback to obtain the rotor position of the permanent magnet synchronous motor, which specifically includes:

[0036] The exponential approach law adaptive law is designed to dynamically adjust the gradient search gain by introducing an exponential approach law, and the real part of the magnetic flux amplitude error in the rotating coordinate system is substituted into an exponential function to generate a dynamic gain coefficient;

[0037] Based on the dynamic gain coefficient, the rotor flux estimation value is calculated by combining the current component of the permanent magnet synchronous motor in the stationary coordinate system, the flux estimation value and the inductance coefficient;

[0038] The rotor position of the permanent magnet synchronous motor is obtained by deriving the rotor flux estimation value through an inverse tangent function.

[0039] Further, the expression for generating the dynamic gain coefficient is specifically as follows:

[0040]

[0041] In the above formula, k(χ2) represents the dynamic gain coefficient, χ2 represents the real part of the magnetic flux amplitude error in the rotating coordinate system, and k0 represents the initial gain coefficient of the exponential approach law.

[0042] The second technical solution adopted by the present application is: a non-linear observer-based electrolytic capacitor-free permanent magnet motor control system, comprising:

[0043] The first module is used to introduce a gradient search mechanism based on the stator voltage equation of the permanent magnet synchronous motor in the stationary coordinate system to construct a flux observer equation;

[0044] The second module is used to obtain the voltage component and the current component of the permanent magnet synchronous motor in the stationary coordinate system, and to observe the flux observer equation to obtain the real part of the magnetic flux amplitude error in the rotating coordinate system;

[0045] The third module is used to design an exponential approach law adaptive law, introduce an exponential approach law to dynamically adjust the gradient search gain, and combine the real part of the magnetic flux amplitude error in the rotating coordinate system as feedback to obtain the rotor position of the permanent magnet synchronous motor.

[0046] The method and system have the advantages that the method introduces a gradient search mechanism based on a stator voltage equation of a permanent magnet synchronous motor in a stationary coordinate system, constructs a flux linkage observer equation, further obtains voltage components and current components of the permanent magnet synchronous motor in the stationary coordinate system, observes the flux linkage observer equation, obtains a real component of a flux linkage amplitude error in a rotating coordinate system, uses the estimated flux linkage error value as a feedback, finally designs an exponential reaching law adaptive law, introduces an exponential reaching law to dynamically adjust a gradient search gain and combines the real component of the flux linkage amplitude error in the rotating coordinate system as feedback to obtain the rotor position of the permanent magnet synchronous motor, dynamically optimizes the gain to adapt to different working conditions, adjusts the k value in real time through the exponential reaching law, reduces the gain at low speed to enhance stability, increases the gain at high speed to speed up convergence, and can quickly and accurately track the real position of the rotor of the permanent magnet synchronous motor. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is a step flow chart of the non-linear observer-based electrolytic capacitor-free permanent magnet motor control method of the application;

[0048] Figure 2 is a structural block diagram of the non-linear observer-based electrolytic capacitor-free permanent magnet motor control system of the application;

[0049] Figure 3 is a non-linear observer-based electrolytic capacitor-free permanent magnet motor control structure schematic diagram provided by the embodiment of the application;

[0050] Figure 4 is a flux linkage observation error phase plane schematic diagram under a conventional method provided by the embodiment of the application;

[0051] Figure 5 is a flux linkage observation error phase plane schematic diagram of an adaptive gain coefficient k provided by the embodiment of the application. DETAILED DESCRIPTION

[0052] The application will be further described in detail below in combination with the drawings and specific embodiments. For the step numbers in the following embodiments, only the setting is for the convenience of description, and the order between the steps is not limited in any way, and the execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0053] First of all, it needs to be pointed out that the existing fixed gain cannot adapt to dynamic working conditions. The error state equation of the existing stator flux linkage is as shown in the following formula:

[0054]

[0055] wherein, represents the differential of the vector χ real part, The differential of the imaginary part of the vector χ, χ represents a variable after coordinate transformation of the stator flux linkage vector error, and the specific transformation formula is as follows:

[0056]

[0057] Wherein, The error value between the stator flux linkage observation variable and the actual value is represented by θ e The actual position of the motor rotor is represented by Ω(v), which is a linear transformation of the motor speed variable, and is represented as:

[0058]

[0059] According to the existing error state equation of the stator flux linkage, the phase plane diagram of the flux linkage error is drawn, as shown in Figure 4 It can be seen that as long as χ2 is greater than 1.5, the convergence path will be along the trajectory 2.

[0060] Therefore, the traditional method adopts a fixed gradient search gain (k value), which cannot be dynamically adjusted according to the running state of the motor (such as speed, load change). At low speed: the fixed gain may cause the observation error to converge slowly, and even the unstable phenomenon of the reverse rotation of the flux linkage. At high speed: the fixed gain may be too large, causing overshoot or oscillation, affecting the dynamic response speed. The convergence path is non-optimal, and under the fixed gain, the convergence path of the error dynamic equation may be detoured, causing the error to first increase and then converge, prolonging the adjustment time. When the speed is reversed or the load is suddenly increased, the observer with fixed gain may not be able to quickly track the true position. And relying on empirical parameter adjustment, the gain λ and k need to be manually debugged, and different motors or working conditions need to be adjusted again, which has poor engineering practicability.

[0061] Based on this, the embodiment of the present application can dynamically adjust the gradient search gain k value, thereby enhancing stability at low speed, improving response speed at high speed, and adapting to different working conditions and parameter changes, as shown in Figure 5

[0062] Referring to Figure 1 and Figure 3 , the present application provides a non-linear observer-based electrolytic capacitor-free permanent magnet motor control method, which comprises the following steps:

[0063] S100, based on the stator voltage equation of the permanent magnet synchronous motor in the stationary coordinate system, a gradient search mechanism is introduced to construct the flux linkage observer equation;

[0064] Specifically, the stator voltage equation of the permanent magnet synchronous motor in the stationary coordinate system is obtained; the stator voltage equation is deformed to construct the dynamic equation of the flux linkage; the gradient search mechanism is introduced to correct the dynamic equation of the flux linkage by error feedback correction integrator to construct the flux linkage observer equation.​

[0065] In this embodiment, the flux linkage observer equations are constructed, and the stator voltage equations of the permanent magnet synchronous motor (PMSM) can be expressed in the stationary coordinate system (αβ axis) as follows:

[0066]

[0067] Where, ψ s For stator flux linkage.

[0068] The dynamic equation of the magnetic flux can be obtained through deformation: This equation represents the basic integrator form of the flux linkage observer, but pure integrators suffer from DC bias and initial error accumulation problems. To address these integrator issues, current techniques introduce a gradient search mechanism to correct the integrator through error feedback. The observer equation is as follows:

[0069]

[0070] In the above formula, Represent the flux linkage observer equation, v αβ R represents the component of the motor terminal voltage in the stationary coordinate system (αβ axis). s i represents the stator winding resistance. αβ λ represents the component of the motor stator current in the stationary coordinate system (αβ axis), and λ represents the adjustment coefficient of the gradient search mechanism. This represents the rotor flux linkage estimate, and k represents the gradient search gain. ψ represents an orthogonal flux linkage vector. e This indicates the rated amplitude of the permanent magnet flux linkage.

[0071] S200: Obtain the voltage and current components of the permanent magnet synchronous motor in the stationary coordinate system, observe the flux linkage observer equation, and obtain the real component of the flux linkage amplitude error in the rotating coordinate system.

[0072] S210. Acquire the voltage and current components of the permanent magnet synchronous motor in the stationary coordinate system;

[0073] S220. Based on the voltage and current components of the permanent magnet synchronous motor in the stationary coordinate system, the stator flux estimate to be updated is obtained by observing according to the flux observer equation.

[0074] S230. Update the stator flux linkage estimate to be updated by numerical integration to obtain the stator flux linkage estimate.

[0075] In this embodiment, the stator flux linkage estimate is observed based on the flux linkage equation, and v is collected in real time. αβ and i αβ Based on the current error χ², calculate k, and calculate... and obtaining the stator flux linkage estimation value The stator flux linkage estimation value is updated by numerical integration (such as Euler method), and the expression is as follows:

[0076]

[0077] In the above formula, represents the stator flux linkage estimation value, represents the flux linkage observer equation, t represents the current time, and Δt represents the sampling period of the discrete time system.

[0078] S240, based on the voltage component and the current component of the permanent magnet synchronous motor in the stationary coordinate system, the voltage of the permanent magnet synchronous motor is calculated to obtain the approximate stator flux linkage value;

[0079] In this embodiment, the motor voltage is calculated, and the real-time measurement of v αβ and i αβ is calculated to obtain the approximate stator flux linkage value, and ψ s is obtained by the following method, and the expression is as follows:

[0080]

[0081] In the above formula, ψ s represents the approximate stator flux linkage value, ω c represents the low-pass filter coefficient of the flux linkage, s represents the Laplace operator, v αβ represents the component of the motor terminal voltage in the stationary coordinate system (αβ axis), R s represents the stator winding resistance, i αβ represents the component of the motor stator current in the stationary coordinate system (αβ axis).

[0082] S250, the stator flux linkage estimation value is subtracted from the approximate stator flux linkage value to obtain the flux linkage error value in the stationary coordinate system;

[0083] S260, the flux linkage error value in the stationary coordinate system is multiplied by the rotation factor to convert into the coordinate system (dq axis) rotating synchronously with the rotor to obtain the real part of the flux linkage amplitude error in the rotating coordinate system.

[0084] In this embodiment, the flux linkage error is calculated: Then, based on the error, it is brought into , that is, the flux linkage error in the stationary coordinate system (αβ axis) is multiplied by the rotation factor to obtain Convert to the coordinate system (dq axis) synchronous with the rotation of the rotor. χ2 is the real part of the flux linkage amplitude error in the rotating coordinate system, as the core feedback signal of adaptive gain adjustment, directly determines the convergence speed and stability of the observer. The calculation formula is as follows:

[0085]

[0086] In the above formula, χ2 represents the real part of the flux linkage amplitude error in the rotating coordinate system, ψ e represents the rated amplitude of the permanent magnet flux linkage, represents the flux linkage error value in the stationary coordinate system, θ e represents the actual position of the motor rotor, represents the estimated value of the rotor position, represents the rotation factor constructed based on the estimated rotor position.

[0087] S300, design exponential approach law adaptive law, introduce exponential approach law dynamically adjust gradient search gain and combine the real part of the flux linkage amplitude error in the rotating coordinate system as feedback, get the rotor position of the permanent magnet synchronous motor.

[0088] S310, design exponential approach law adaptive law, introduce exponential approach law dynamically adjust gradient search gain, substitute the real part of the flux linkage amplitude error in the rotating coordinate system into the exponential function, generate dynamic gain coefficient;

[0089] In this embodiment, the exponential approach law adaptive law is designed, the exponential approach law is introduced to dynamically adjust k, χ2 is obtained, χ2 reflects the real-time state of the flux linkage amplitude error, and χ2 is substituted into the exponential function to generate a dynamic gain k: The size of k0 can be adjusted according to the actual debugging effect, and in the embodiment of the present application, it is set to 0.5. At the same time, the parameter k needs to be limited in amplitude, and is selected as [-1, 1].

[0090] S320, based on the dynamic gain coefficient, combine the current component of the permanent magnet synchronous motor in the stationary coordinate system, the flux linkage estimated value and the inductance coefficient, calculate the rotor flux linkage estimated value;

[0091] S330, derive the rotor flux linkage estimated value through the arctangent function, get the rotor position of the permanent magnet synchronous motor.

[0092] In this embodiment, the rotor position is derived through the stator flux linkage estimated value combined with the stator current i αβ and the inductance L s , the rotor flux linkage is calculated, and the rotor position is directly derived by using the arctangent function. The rotor position is calculated by arctangent:

[0093] Therefore, the embodiment of the present application can significantly improve the dynamic performance. The prior art (fixed gradient search gain k) often has two problems: low-speed oscillation and high-speed lag, because the gain cannot be adaptively adjusted. The present application improves the dynamic adjustment through the exponential approach law, automatically reduces k when the observation error is large, changes the convergence path; when the error is small, quickly increases k to the maximum value, speeds up the convergence, and improves the dynamic and steady-state performance of the system. Second: convergence path optimization, the fixed gain of the prior art leads to a non-ideal convergence path of the error dynamic equation, the present application improves: adaptive k(x2) makes the convergence path approach a straight line, shortens the convergence time. Four: engineering usability, the prior art needs to rely on experience to manually tune parameters, and the present application only needs to set k0 one parameter.

[0094] In summary, the embodiment of the present application has the following differences compared with the prior art:

[0095] 1) Dynamic optimization gain to adapt to different working conditions, adjust the k value in real time through the exponential approach law, reduce the gain at low speed to enhance stability, increase the gain at high speed to speed up convergence, avoid the "divergence before convergence" problem caused by the fixed gain of the traditional method.

[0096] 2) Shorten the convergence time, optimize the convergence path of the error dynamic equation, make it closer to directly approach zero error, and speed up the position estimation.

[0097] 3) Eliminate the need for manual parameter tuning, automatically adjust the gain through the adaptive law, reduce the dependence on engineers' experience.

[0098] The embodiment of the present application has the following advantages compared with the prior art:

[0099] 1) Adaptive gradient search gain design: method of dynamically adjusting k value based on exponential approach law.

[0100] 2) Error feedback mechanism: use the estimated flux linkage error value as the feedback quantity.

[0101] 3) Compound observer structure: nonlinear flux linkage observer implementation scheme integrating adaptive k value.

[0102] Reference Figure 2 , the non-linear observer-based electrolytic capacitor-free permanent magnet motor control system comprises:

[0103] The first module 201 is used for introducing a gradient search mechanism based on the stator voltage equation of the permanent magnet synchronous motor in the stationary coordinate system, and constructing a flux linkage observer equation;

[0104] The second module 202 is configured to acquire voltage components and current components of the permanent magnet synchronous motor in a stationary coordinate system, observe a flux linkage observer equation, and obtain a real component of a flux linkage amplitude error in a rotating coordinate system;

[0105] The third module 203 is configured to design an exponential approach law adaptive law, introduce an exponential approach law to dynamically adjust a gradient search gain, and combine the real component of the flux linkage amplitude error in the rotating coordinate system as feedback to obtain a rotor position of the permanent magnet synchronous motor.

[0106] The contents in the method embodiments are applicable to the system embodiments, the system embodiments specifically implement the same functions as the method embodiments, and achieve the same beneficial effects as the method embodiments.

[0107] The above is a specific description of the preferred embodiments of the application, but the application is not limited to the embodiments, and those skilled in the art can make various equivalent modifications or replacements without departing from the spirit of the application. These equivalent modifications or replacements are all included in the scope defined by the claims of the application.

Claims

1. A capacitorless permanent magnet motor control method based on a nonlinear observer, characterized in that, Includes the following steps: Based on the stator voltage equation of permanent magnet synchronous motor in stationary coordinate system, a gradient search mechanism is introduced to construct the flux linkage observer equation; The voltage and current components of the permanent magnet synchronous motor in the stationary coordinate system are obtained, and the flux linkage observer equation is observed to obtain the real component of the flux linkage amplitude error in the rotating coordinate system. An adaptive law with an exponential approach is designed. The exponential approach law is introduced to dynamically adjust the gradient search gain and combine the real part of the flux linkage amplitude error in the rotating coordinate system as feedback to obtain the rotor position of the permanent magnet synchronous motor.

2. The electrolytic capacitor-free permanent magnet motor control method based on a nonlinear observer according to claim 1, characterized in that, The step of capturing images with different polarization directions based on an infrared thermal imager and a polarizer specifically includes: Obtain the stator voltage equation of the permanent magnet synchronous motor in the stationary coordinate system; The stator voltage equation is transformed to construct the dynamic equation of the magnetic flux. A gradient search mechanism is introduced, and the dynamic equation of the magnetic flux is corrected by an error feedback correction integrator to construct the magnetic flux observer equation.

3. The electrolytic capacitor-free permanent magnet motor control method based on a nonlinear observer according to claim 2, characterized in that, The specific expression for the flux linkage observer equation is as follows: In the above formula, Represent the flux linkage observer equation, v αβ R represents the component of the motor terminal voltage in the stationary coordinate system (αβ axis). s i represents the stator winding resistance. αβ λ represents the component of the motor stator current in the stationary coordinate system (αβ axis), and λ represents the adjustment coefficient of the gradient search mechanism. This represents the rotor flux linkage estimate, and k represents the gradient search gain. ψ represents an orthogonal flux linkage vector. e This indicates the rated amplitude of the permanent magnet flux linkage.

4. The electrolytic capacitor-free permanent magnet motor control method based on a nonlinear observer according to claim 3, characterized in that, The step of obtaining the voltage and current components of the permanent magnet synchronous motor in the stationary coordinate system, observing the flux linkage observer equation, and obtaining the real component of the flux linkage amplitude error in the rotating coordinate system specifically includes: The voltage and current components of the permanent magnet synchronous motor in the stationary coordinate system are acquired. Based on the voltage and current components of the permanent magnet synchronous motor in the stationary coordinate system, the stator flux estimate to be updated is obtained by observing according to the flux observer equation. The stator flux linkage estimate is obtained by updating the stator flux linkage estimate by numerical integration. Based on the voltage and current components of the permanent magnet synchronous motor in the stationary coordinate system, the voltage of the permanent magnet synchronous motor is calculated to obtain an approximate stator flux linkage value. The stator flux linkage estimate is calculated by subtracting the approximate stator flux linkage value to obtain the flux linkage error value in the stationary coordinate system. The flux linkage error value in the stationary coordinate system is multiplied by the rotation factor and transformed into a coordinate system (dq axis) that rotates synchronously with the rotor to obtain the real component of the flux linkage amplitude error in the rotating coordinate system.

5. The electrolytic capacitor-free permanent magnet motor control method based on a nonlinear observer according to claim 4, characterized in that, The specific expression for updating the stator flux linkage estimate to be updated is as follows: In the above formula, This represents the estimated value of the stator flux linkage. Let represent the magnetic flux observer equation, t represent the current time, and Δt represent the sampling period of the discrete-time system.

6. The electrolytic capacitor-free permanent magnet motor control method based on a nonlinear observer according to claim 5, characterized in that, The specific expression for calculating the approximate stator flux linkage value is as follows: In the above formula, ψ s ω represents the approximate value of the stator flux linkage. c The low-pass filter coefficients of the flux linkage are represented by s, and the Laplace operator is represented by v. αβ R represents the component of the motor terminal voltage in the stationary coordinate system (αβ axis). s i represents the stator winding resistance. αβ This represents the component of the motor stator current in the stationary coordinate system (αβ axis).

7. The electrolytic capacitor-free permanent magnet motor control method based on a nonlinear observer according to claim 6, characterized in that, The specific expression for calculating the real component of the flux linkage amplitude error in the rotating coordinate system is as follows: In the above formula, χ2 represents the real component of the flux linkage amplitude error in the rotating coordinate system, and ψ e This indicates the rated amplitude of the permanent magnet flux linkage. θ represents the flux linkage error in the stationary coordinate system. e Indicates the actual position of the motor rotor. This represents an estimated value of the rotor position. This represents the rotation factor constructed based on the estimated rotor position.

8. The electrolytic capacitor-free permanent magnet motor control method based on a nonlinear observer according to claim 7, characterized in that, The step of designing an adaptive exponential reaching law, which dynamically adjusts the gradient search gain and incorporates the real component of the flux linkage amplitude error in the rotating coordinate system as feedback, to obtain the rotor position of the permanent magnet synchronous motor, specifically includes: The exponential reaching law adaptive law is designed, and the gradient search gain is dynamically adjusted by introducing the exponential reaching law. The real part of the flux linkage amplitude error in the rotating coordinate system is substituted into the exponential function to generate the dynamic gain coefficient. Based on the dynamic gain coefficient, combined with the current component, flux linkage estimate and inductance coefficient of the permanent magnet synchronous motor in the stationary coordinate system, the rotor flux linkage estimate is calculated. The rotor position of the permanent magnet synchronous motor is obtained by deriving the rotor flux estimate through the arctangent function.

9. The electrolytic capacitor-free permanent magnet motor control method based on a nonlinear observer according to claim 8, characterized in that, The specific expression for generating the dynamic gain coefficient is as follows: In the above formula, k(χ2) represents the dynamic gain coefficient, χ2 represents the real component of the flux linkage amplitude error in the rotating coordinate system, and k0 represents the initial gain coefficient of the exponential reaching law.

10. A capacitorless permanent magnet motor control system based on a nonlinear observer, characterized in that, Includes the following modules: The first module is used to construct the flux linkage observer equation based on the stator voltage equation of the permanent magnet synchronous motor in the stationary coordinate system by introducing a gradient search mechanism. The second module is used to obtain the voltage and current components of the permanent magnet synchronous motor in the stationary coordinate system, observe the flux linkage observer equation, and obtain the real component of the flux linkage amplitude error in the rotating coordinate system. The third module is used to design an exponential reaching law adaptive law. It introduces an exponential reaching law to dynamically adjust the gradient search gain and combines the real part of the flux linkage amplitude error in the rotating coordinate system as feedback to obtain the rotor position of the permanent magnet synchronous motor.

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