Aerospace permanent magnet motor flux linkage online estimation method based on back electromotive force observer

Abstract

The invention discloses a spaceflight permanent magnet motor flux linkage online estimation method based on a back electromotive force observer. The method comprises the following steps: calculating a back electromotive force constraint coefficient; constructing a counter electromotive force observer to stably observe the counter electromotive force; and calculating a counter potential real-time value, carrying out peak detection to obtain a counter potential amplitude, and calculating a flux linkage value on line by using an analytic relationship between the counter potential and the flux linkage so as to realize reliable estimation of the flux linkage. The method is suitable for high and low temperature, thermal vacuum and other closed test environments, and external flux linkage measurement equipment is not needed; volatility and temperature drift sensitivity of direct estimation of flux linkage are avoided, and estimation errors in high and low temperature environments are smaller; the device only depends on easy-to-measure parameters such as motor end voltage, current and rotating speed, is simple in structure, and can be directly applied to aerospace motor environment tests. And reliable data support is provided for flux linkage temperature characteristic analysis, on-orbit performance inference and life prediction.

Description

Technical Field

[0001] This invention relates to an online estimation method for flux linkage of aerospace permanent magnet motors based on a back EMF observer, belonging to the technical field of parameter estimation for aerospace permanent magnet motors. Background Technology

[0002] As a core power component for spacecraft attitude control, actuator drive, and critical equipment inside and outside the cabin, the operational reliability of permanent magnet motors directly affects the safety of space missions and their long-term on-orbit performance. To ensure that permanent magnet motors can operate stably under extreme conditions such as orbital vacuum and severe temperature cycling, the aerospace industry must conduct comprehensive ground verification before the product is launched, including high and low temperature environment testing and thermal vacuum testing.

[0003] Among these verification stages, the characteristic testing of the flux linkage of permanent magnet motors under high and low temperature conditions is particularly critical. This is because the magnetic properties of permanent magnets undergo reversible or irreversible decay with temperature, and changes in flux linkage directly affect the motor's torque output capability, control accuracy, and on-orbit life assessment. Based on this application requirement, in order to accurately obtain the flux linkage variation law of permanent magnet motors under high and low temperature conditions on the ground, and to determine its performance loss and support life prediction after launch, a method that can accurately obtain the flux linkage value of aerospace permanent magnet motors is urgently needed.

[0004] In high and low temperature environment testing, aerospace permanent magnet motors are typically placed in sealed devices such as high and low temperature chambers and thermal vacuum chambers for environmental simulation tests. Unlike open environments at room temperature, these sealed test conditions do not allow the use of external flux linkage measuring instruments (such as fluxmeters, search coil testing systems, etc.). During the test, only basic state information such as motor terminal voltage, current, and temperature can be collected. Therefore, how to achieve online flux linkage estimation relying solely on these available electrical quantities in the absence of specialized flux linkage measuring equipment becomes a very important technical problem.

[0005] Existing online flux linkage estimation methods mainly rely on direct estimation. For example, the chapter on online identification of permanent magnet flux linkage in embedded permanent magnet synchronous motors in the *Journal of Electrical Engineering* mentions using an extended Kalman filter to directly estimate the permanent magnet flux linkage as the observation target. Chinese invention patent CN102651629A discloses an online method for estimating permanent magnet flux linkage, which directly calculates the flux linkage value through a back-calculation method based on a mathematical model of the motor containing flux linkage information. However, its drawbacks include significant fluctuations in flux linkage itself, unstable estimation results, and high sensitivity to model accuracy and noise. In high and low temperature testing environments, factors such as motor parameter drift, increased measurement noise, and attenuation of the back EMF signal further exacerbate estimation errors, significantly reducing the stability and accuracy of direct flux linkage estimation. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of the existing technology. Aerospace permanent magnet motors require extreme environmental testing, such as high and low temperatures and thermal vacuum, before on-orbit application. The characteristic of their flux linkage changing with temperature is a key indicator for evaluating on-orbit performance and lifespan. However, flux linkage measurement equipment cannot be used under closed-environment testing conditions, and traditional direct estimation methods suffer from the difficulty of obtaining stable and reliable flux linkage values. Therefore, this invention proposes an online flux linkage estimation method for aerospace permanent magnet motors based on a back-EMF observer.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for online estimation of flux linkage of aerospace permanent magnet motors based on a back-potential observer, characterized by the following steps: S1 calculates the back EMF constraint coefficient and constructs the formula for calculating the back EMF constraint coefficient γ: , where ψ f0 The nominal flux linkage of the motor, n max For the nominal maximum no-load speed, V dc This refers to the nominal DC bus voltage. S2 constructs a back potential observer and establishes a coordinate transformation formula: , , The measured three-phase current i of the aerospace permanent magnet motor a i b i c and three-phase voltage u a u b u c Substituting into the coordinate transformation formula, the transformed current i is calculated. α and voltage u α , Using the transformed current i α and voltage u α Construct the back potential observer equation: , Among them, i α * is the current value estimated by the back EMF observer, R s For the resistance of the aerospace permanent magnet motor, L s The inductance is the inductance of the aerospace permanent magnet motor, and k is the proportional coefficient of the back EMF observer, k>100. , For symbolic functions, ; S3 calculates the back EMF amplitude. When the back EMF observer constructed in step S2 is running stably, E α The peak value of the back EMF of the aerospace permanent magnet motor is obtained by peak detection. αf ; S4 Estimation of Flux Linkage in Aerospace Permanent Magnet Motors: Constructing the Calculation Formula for Flux Linkage ψf in Aerospace Permanent Magnet Motors: Where n is the measured real-time rotational speed of the aerospace permanent magnet motor, and the back EMF constraint coefficient γ obtained in step S1 and the back EMF amplitude E obtained in step S3 are used. αf Substituting the values ​​into the calculation, we obtain the flux linkage ψf of the aerospace permanent magnet motor.

[0008] The beneficial effects of this invention are mainly reflected in: 1. Suitable for closed testing environments such as high and low temperatures and thermal vacuum, without the need for external magnetic flux measurement equipment; 2. It avoids the fluctuations and temperature drift sensitivity of direct magnetic flux estimation, resulting in smaller estimation errors under high and low temperature environments; 3. It relies only on easily measurable parameters such as motor terminal voltage, current, and speed, has a simple structure, and can be directly applied to aerospace motor environmental testing; 4. Provides reliable data support for the analysis of flux linkage temperature characteristics, inference of on-orbit performance, and prediction of lifetime. Attached Figure Description

[0009] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a flowchart illustrating an online estimation method for the flux linkage of a space permanent magnet motor based on a back EMF observer, according to the present invention.

[0010] Figure 2 This is a block diagram illustrating the implementation of the back EMF observer in this invention. Detailed Implementation

[0011] 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, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0012] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in the present application can be combined with each other.

[0013] This invention provides an online estimation method for flux linkage of aerospace permanent magnet motors based on a back-EMF observer. The method involves calculating the back-EMF constraint coefficient, designing a back-EMF observer for stable observation of the back-EMF, and using the analytical relationship between the back-EMF and flux linkage to calculate the flux linkage value online, thus achieving reliable flux linkage estimation. Compared to traditional direct estimation methods, this invention improves the stability of flux linkage estimation under high and low temperature conditions, making it particularly suitable for environmental testing of aerospace motors in confined environments.

[0014] Specifically, such as Figure 1 and Figure 2 As shown, an online estimation method for the flux linkage of a space permanent magnet motor based on a back-potential observer includes the following steps: Calculate the back EMF constraint coefficient and construct the formula for calculating the back EMF constraint coefficient γ: , where ψ f0 The nominal flux linkage of the motor, n max For the nominal maximum no-load speed, V dc This is the nominal DC bus voltage.

[0015] The nominal flux linkage ψf0 and the nominal maximum no-load speed n of the motor are used to determine the motor's nominal flux linkage ψf0 and nominal maximum no-load speed n. max and nominal DC bus voltage V dc Substitute the values ​​into the formula to calculate the back EMF constraint coefficient γ.

[0016] Construct a back potential observer and formulate a coordinate transformation formula: , , The measured three-phase current i of the aerospace permanent magnet motor a i b i c and three-phase voltage u a u b u c Substituting into the coordinate transformation formula, the transformed current i is calculated. α and voltage u α , Using the transformed current i α and voltage u α Construct the back potential observer equation: , Among them, i α * is the current value estimated by the back EMF observer, R s For the resistance of the aerospace permanent magnet motor, L s The inductance is the inductance of the aerospace permanent magnet motor, and k is the proportional coefficient of the back EMF observer, k>100. , For symbolic functions, .

[0017] Calculate the back EMF amplitude. When the back EMF observer constructed in step S2 is running stably, E α The peak value of the back EMF of the aerospace permanent magnet motor is obtained by peak detection. αf ; Due to E α Since the signal is sinusoidal, the amplitude E of the back electromotive force needs to be obtained by peak detection of the signal. αf This is used for subsequent flux linkage calculations.

[0018] Estimating the flux linkage of aerospace permanent magnet motors: Constructing the calculation formula for the flux linkage ψf of aerospace permanent magnet motors: Where n is the measured real-time rotational speed of the aerospace permanent magnet motor, and the back EMF constraint coefficient γ obtained in step S1 and the back EMF amplitude E obtained in step S3 are used. αf Substituting the values ​​into the calculation, we obtain the flux linkage ψf of the aerospace permanent magnet motor.

[0019] In one specific embodiment, the parameters of the aerospace permanent magnet motor are as follows: Inductance Ls=0.125H, stator resistance Rs=0.5Ω, permanent magnet flux linkage ψf0=0.83Wb, maximum no-load speed nmax=60rpm, DC bus voltage Vdc=15V.

[0020] The implementation process of the online flux estimation method for aerospace permanent magnet motors based on back-potential observers is as follows: Calculate the back EMF constraint coefficient Substituting the motor's nominal flux linkage ψf0 = 0.83, maximum no-load speed nmax = 60, and DC bus voltage Vdc = 15 into the following formula, the back EMF constraint coefficient γ is calculated: .

[0021] The three-phase parameters of aerospace permanent magnet motors are generally classified, and this embodiment will not display their data. Instead, the back EMF observer equation is constructed by transforming the measured parameters. When the constructed back EMF observer is running stably, the real-time value of the back EMF of the aerospace permanent magnet motor, E, can be obtained. α ,Right now After obtaining the back EMF amplitude through peak detection, it can be passed... The flux linkage ψf of the aerospace permanent magnet motor was calculated.

[0022] As can be seen from the above description, it is suitable for closed testing environments such as high and low temperatures and thermal vacuum, without the need for external flux measurement equipment; it avoids the fluctuation and temperature drift sensitivity of direct flux estimation, and the estimation error is smaller in high and low temperature environments; it only relies on easily measurable parameters such as motor terminal voltage, current, and speed, and has a simple structure that can be directly applied to aerospace motor environmental testing; it provides reliable data support for flux temperature characteristic analysis, on-orbit performance inference, and life prediction.

[0023] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent in such process, method, article, or apparatus / device.

[0024] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for online estimation of flux linkage of aerospace permanent magnet motors based on a back-potential observer, characterized in that... Includes the following steps: S1 calculates the back EMF constraint coefficient and constructs the formula for calculating the back EMF constraint coefficient γ: , where ψ f0 The nominal flux linkage of the motor, n max For the nominal maximum no-load speed, V dc This refers to the nominal DC bus voltage. S2 constructs a back potential observer and establishes a coordinate transformation formula: , , The measured three-phase current i of the aerospace permanent magnet motor a i b i c and three-phase voltage u a u b u c Substituting into the coordinate transformation formula, the transformed current i is calculated. α and voltage u α , Using the transformed current i α and voltage u α Construct the back potential observer equation: , Among them, i α * is the current value estimated by the back EMF observer, R s For the resistance of the aerospace permanent magnet motor, L s The inductance is the inductance of the aerospace permanent magnet motor, and k is the proportional coefficient of the back EMF observer, k>100. , For symbolic functions, ; S3 calculates the back EMF amplitude. When the back EMF observer constructed in step S2 is running stably, E α The peak value of the back EMF of the aerospace permanent magnet motor is obtained by peak detection. αf ; S4 estimates the flux linkage of aerospace permanent magnet motors and constructs a formula for calculating the flux linkage ψf of aerospace permanent magnet motors: Where n is the measured real-time rotational speed of the aerospace permanent magnet motor, and the back EMF constraint coefficient γ obtained in step S1 and the back EMF amplitude E obtained in step S3 are used. αf Substituting the values ​​into the calculation, we obtain the flux linkage ψf of the aerospace permanent magnet motor.

Images