Permanent magnet synchronous motor rotor position observation method

Abstract

The invention relates to the field of permanent magnet synchronous motors, and discloses a permanent magnet synchronous motor rotor position observation method, which comprises the steps of establishing a sliding-mode observer based on a fast superhelix control theory, and obtaining an electrical angular velocity estimated value and a rotor position angle estimated value of a PMSM through the sliding-mode observer; calculating a voltage characteristic quantity according to the voltage estimation value and the current estimation value obtained by the sliding mode observer; and carrying out online optimization and tracking on the maximum value of the voltage characteristic quantity by adopting a variable step size hill climbing method to realize compensation of the rotor position angle estimation value. According to the invention, the improved fast superhelix algorithm is adopted to replace an exponential reaching law in a sliding mode observer, so that buffeting and ripple waves in back electromotive force estimation are reduced; the FST-SMO based on the d-q axis is designed to estimate the rotating speed and the rotor position, and the dynamic performance and the observation precision are improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of permanent magnet synchronous motors, and in particular to a method for observing the rotor position of a permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motor (PMSM) has excellent characteristics such as high power density, high efficiency, and wide speed regulation range, and has received extensive attention and application in aerospace, electric vehicles and other fields. PMSM usually requires an encoder to obtain accurate speed and rotor position information. However, the installation of the position sensor is easily affected by the environment, which will increase the system cost and reduce the system reliability. Therefore, position sensorless control technology has been widely studied and applied.

[0003] Among many position sensorless control methods, the sliding mode observer (SMO) has the characteristics of simple design, strong robustness, and insensitivity to changes in its own parameters, making it a very promising position sensorless control solution. However, the traditional SMO observer inevitably has a jitter phenomenon, which leads to a high content of high-order harmonics in the observed back electromotive force, which will eventually affect the accuracy of the rotor position estimation. For this reason, a low-pass filter is usually required in the SMO observer, but the use of a low-pass filter will bring about a phase lag problem, resulting in an estimated error in the motor rotor position. In addition, the commonly used position error compensation method has a low level of intelligent control, lacks adaptability, and has a complex algorithm, resulting in poor results. Summary of the invention

[0004] The embodiments of the present disclosure provide a method for observing the rotor position of a permanent magnet synchronous motor to solve or alleviate one or more of the above technical problems in the prior art.

[0005] According to one aspect of the present disclosure, a method for observing the rotor position of a permanent magnet synchronous motor is provided, comprising:

[0006] A sliding mode observer based on fast superhelical control theory is established, and an estimated value of the electrical angular velocity and an estimated value of the rotor position angle of the PMSM are obtained through the sliding mode observer;

[0007] Calculating a voltage characteristic value according to the voltage estimation value and the current estimation value obtained by the sliding mode observer;

[0008] The variable step-size hill climbing method is used to perform online optimization and tracking of the maximum value of the voltage characteristic quantity to achieve compensation for the estimated value of the rotor position angle.

[0009] In a possible implementation, a sliding mode observer based on fast superhelical control theory is established, and obtaining an estimated value of the electrical angular velocity and an estimated value of the rotor position angle of the PMSM through the sliding mode observer includes:

[0010] According to the PMSM voltage equation in the dq coordinate system, the PMSM current equation in the dq coordinate system is established;

[0011] Constructing a sliding mode observer, and obtaining a current estimation value in a dq coordinate system through the sliding mode observer;

[0012] A current error equation is established based on a sliding mode observer and a PMSM current equation in a dq coordinate system, and a current observation error is calculated according to the current error equation;

[0013] The current observation error is selected as the sliding surface;

[0014] According to the fast superhelical control theory, the sliding mode control input V is designed. d and V q The control law of

[0015] In the dq coordinate system, based on the sliding mode control input V d and V q The control law is used to obtain the observed value of back electromotive force;

[0016] Based on the back EMF observations, the PMSM electrical angular velocity estimate and rotor position angle estimate are calculated.

[0017] In one possible implementation, the PMSM voltage equation in the dq coordinate system is:

[0018]

[0019] In the formula, i d 、i q 、u d 、u q are the d-axis stator current, q-axis stator current, d-axis stator voltage and q-axis stator voltage in the dq coordinate system respectively; R s , L d , L q They are stator resistance, d-axis stator inductance and q-axis stator inductance respectively; ω e is the electrical angular velocity of the rotor; ψ f is the flux linkage produced by the permanent magnet;

[0020] The PMSM current equation in the dq coordinate system is:

[0021]

[0022] In the formula, L represents the matrix coefficient; A represents the matrix variable; θ e Indicates the actual electrical angle; E d 、E q They are the d-axis back-EMF and q-axis back-EMF in the dq coordinate system respectively;

[0023] The sliding mode observer is:

[0024]

[0025] In the formula, and are the estimated d-axis current and q-axis current in the dq coordinate system, V d and V q is the input of sliding mode control;

[0026] The current error equation is:

[0027]

[0028] In the formula, and They represent the d-axis current observation error and the q-axis current observation error respectively;

[0029] The sliding surface is:

[0030]

[0031] Where, s represents the sliding surface; s d and q denote the d-axis sliding surface and the q-axis sliding surface respectively;

[0032] The control law of sliding mode control inputs Vd and Vq is:

[0033]

[0034] Where k1, k2, k3 and k4 are control parameters;

[0035] When the current estimation value in the dq coordinate system reaches the sliding surface, based on the sliding mode control input V d and V q The back electromotive force observation value obtained by the control law is expressed as:

[0036]

[0037] In the formula, and They are the d-axis back-EMF observation value and the q-axis back-EMF observation value in the dq coordinate system respectively;

[0038] Based on the back EMF observations, the formulas for calculating the PMSM electrical angular velocity estimate and rotor position angle estimate are:

[0039]

[0040] In the formula, and They are the estimated electrical angular velocity and rotor position angle of the PMSM, respectively.

[0041] In a possible implementation, the voltage characteristic quantity is calculated according to the estimated voltage and estimated current of the PMSM in the dq coordinate system.

[0042] In one possible implementation, the PMSM estimated voltage equation is:

[0043]

[0044] In the formula, and They are the estimated d-axis voltage and q-axis voltage in the dq coordinate system respectively; and are the estimated d-axis current and q-axis current in the dq coordinate system respectively; Δθ e is the rotor position angle error value; i d 、i q , are the d-axis stator current and q-axis stator current in the dq coordinate system respectively; L d , L q are the d-axis stator inductance and the q-axis stator inductance respectively; ω e is the electrical angular velocity of the rotor; ψ f is the flux generated by the permanent magnet; R s Indicates the stator resistance.

[0045] In a possible implementation, the calculation formula of the voltage characteristic value δ is:

[0046]

[0047] In the formula, is the estimated value of the q-axis voltage in the dq coordinate system; is the estimated value of the q-axis current in the dq coordinate system; ω e is the electrical angular velocity of the rotor; ψ f is the flux generated by the permanent magnet; Δθ e is the rotor position angle error value; R s Indicates the stator resistance.

[0048] In a possible implementation, a variable step-size hill climbing method is used to track the maximum value of the voltage characteristic quantity to achieve compensation for the estimated value of the rotor position angle. The calculation formula is:

[0049]

[0050] In the formula, Δθ e (k+1) is the compensation angle at time k+1; Δθ e(k) is the compensation angle at time k; Δθ cop is the compensation angle adjustment term; dδ(k) represents the characteristic value of the optimal change direction; dΔθ e (k) represents the characteristic value of the change direction of the compensation angle; C is the step coefficient; δ(k) is the characteristic value of the steady-state voltage of the motor q axis at time k; δ(k-1) is the characteristic value of the steady-state voltage of the motor q axis at time k-1; Δθ e (k-1) is the compensation angle at time k-1.

[0051] The present disclosure has the following beneficial effects: the present disclosure proposes a method for observing the rotor position information of a permanent magnet synchronous motor by using a fast superhelical sliding mode observer (FST-SMO), and adopts an improved fast superhelical algorithm to replace the exponential convergence law in the sliding mode observer, thereby reducing the jitter and the ripple in the estimated back electromotive force; the dq-axis-based FST-SMO is designed to realize the estimation of the rotational speed and the rotor position, thereby avoiding the use of a low-pass filter and improving the dynamic performance and the observation accuracy; in view of non-ideal factors such as control delay, installation error and parameter deviation, the intelligent control hill climbing method is adopted to optimize and compensate the observed position angle, thereby further improving the observation accuracy and the intelligent control level.

[0052] The details of one or more embodiments of the present application are presented in the following drawings and descriptions. Other features and advantages of the present application will become apparent from the accompanying drawings. It should be understood that the above general description and the detailed descriptions below are only exemplary and explanatory and cannot limit the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0054] Figure 1 is a flow chart of a permanent magnet synchronous motor rotor position observation method of this exemplary embodiment;

[0055] Figure 2 is a position angle error diagram of the present exemplary embodiment;

[0056] Figure 3 is a flow chart of the hill climbing compensation algorithm of this exemplary embodiment. DETAILED DESCRIPTION

[0057] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as being limited to the examples set forth herein; on the contrary, these embodiments are provided so that the present disclosure will be more comprehensive and complete, and the concepts of the example embodiments are fully conveyed to those skilled in the art. The described features, structures, or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced while omitting one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known technical solutions are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

[0058] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware units or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0059] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the steps. For example, some steps may be decomposed, while some steps may be combined or partially combined, so the actual execution order may change according to the actual situation.

[0060] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example.

[0061] In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or sub-modules is not necessarily limited to those steps or sub-modules explicitly listed, but may include other steps or sub-modules not explicitly listed or inherent to these processes, methods, products, or apparatuses.

[0062] Figure 1 is a flow chart of a permanent magnet synchronous motor rotor position observation method of this exemplary embodiment. Figure 1As shown, an exemplary embodiment of the present disclosure provides a permanent magnet synchronous motor rotor position observation method, comprising:

[0063] A sliding mode observer based on fast superhelical control theory is established, and an estimated value of the electrical angular velocity and an estimated value of the rotor position angle of the PMSM are obtained through the sliding mode observer;

[0064] Calculating a voltage characteristic value according to the voltage estimation value and the current estimation value obtained by the sliding mode observer;

[0065] The variable step-size hill climbing method is used to perform online optimization and tracking of the maximum value of the voltage characteristic quantity to achieve compensation for the estimated value of the rotor position angle.

[0066] Specifically, a sliding mode observer based on fast superhelical control theory is established, and obtaining the electrical angular velocity estimation value and the rotor position angle estimation value of the PMSM through the sliding mode observer includes:

[0067] According to the PMSM voltage equation in the dq coordinate system, the PMSM current equation in the dq coordinate system is established;

[0068] Constructing a sliding mode observer, and obtaining a current estimation value in a dq coordinate system through the sliding mode observer;

[0069] A current error equation is established based on a sliding mode observer and a PMSM current equation in a dq coordinate system, and a current observation error is calculated according to the current error equation;

[0070] The current observation error is selected as the sliding surface;

[0071] According to the fast superhelical control theory, the sliding mode control input V is designed. d and V q The control law of

[0072] In the dq coordinate system, based on the sliding mode control input V d and V q The control law is used to obtain the observed value of back electromotive force;

[0073] Based on the back EMF observations, the PMSM electrical angular velocity estimate and rotor position angle estimate are calculated.

[0074] In this embodiment, the voltage equation of the permanent magnet synchronous motor in the dq coordinate system can be expressed as:

[0075]

[0076] Where: i d 、i q 、u d 、u qare the stator current and stator voltage in the dq coordinate system respectively; R s , L d , L q are the stator resistance, d-axis and q-axis stator inductance respectively; ω e is the electrical angular velocity of the rotor; ψ f is the flux linkage generated by the permanent magnet.

[0077] According to formula (1), the current equation of PMSM is:

[0078]

[0079] In the formula

[0080] In order to obtain E d and E q , the state equation of the sliding mode observer is constructed as:

[0081]

[0082] in and are the estimated values ​​of dq axis current respectively, where V d and V q is the input quantity of sliding mode control. Subtracting equation (2) from equation (3) yields the current error equation:

[0083]

[0084] In the formula Represents the current observation error. Select the current error as the sliding surface:

[0085]

[0086] According to the fast superhelical control theory, V d and V q The control law can be designed as:

[0087]

[0088] The control parameters k1, k2, k3 and k4 are all greater than zero. When the observed variable (the estimated value of the dq axis current and ) reaches the sliding surface with s d =0,s q = 0, and ( Yes d The derivative of Yes q The back electromotive force observed by FST-SMO can be expressed as:

[0089]

[0090] From formula (2), we can know that the back electromotive force E d and E q The electrical angular velocity information of the PMSM is contained in , which can be estimated by dividing by the flux and then integrating to get the estimated angular position:

[0091]

[0092] Specifically, the voltage characteristic amount is calculated according to the estimated voltage and estimated current of the PMSM in the dq coordinate system.

[0093] In the PMSM sensorless control of this embodiment, the estimated position angle is easily affected by non-ideal factors such as digital control delay, filter phase shift and motor parameter deviation. In order to improve the control accuracy, this embodiment adopts the variable step size hill climbing method to perform online optimization and adaptive compensation of the error angle.

[0094] Considering the position angle error of the permanent magnet synchronous motor in actual state, such as Figure 2 As shown, the voltage equation based on the estimated value is as follows:

[0095]

[0096] in, and are the estimated values ​​of dq axis voltage respectively; Δθ e is the rotor position angle error.

[0097] When using i d = 0, the voltage characteristic value δ can be defined as follows according to equation (9) in steady state:

[0098]

[0099] It can be seen from formula (10) that when there is no position angle error, that is, Δθ e = 0, the voltage characteristic quantity δ will take the maximum value. Therefore, when the maximum value of the upper voltage characteristic quantity is tracked, the position angle error is compensated. The position angle compensation of the proposed variable step size hill climbing method is as follows Figure 3 shown.

[0100] When there is an error in the position angle, the voltage characteristic will deviate from its maximum value. At this time, the hill climbing method will be used to optimize and compensate the position angle. dδ(k) and dΔθ e (k) represent the direction of optimization and compensation respectively. When they are in the same direction, the control method will seek optimal compensation in the forward direction, otherwise it will seek optimal compensation in the reverse direction. That is:

[0101]

[0102] In order to speed up the optimization tracking and avoid oscillation when approaching the maximum value, the variable step size hill climbing method is used:

[0103]

[0104] where Δθ cop is the compensation angle adjustment item; C>0 is the step length coefficient.

[0105] The above are only preferred implementations of the present disclosure, and the protection scope of the present disclosure is not limited to the above embodiments. All technical solutions under the concept of the present disclosure belong to the protection scope of the present disclosure. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present disclosure should be regarded as the protection scope of the present disclosure.

Claims

1. A method for observing the rotor position of a permanent magnet synchronous motor, characterized in that: include: A sliding mode observer based on fast superhelical control theory is established, and an estimated value of the electrical angular velocity and an estimated value of the rotor position angle of the PMSM are obtained through the sliding mode observer; Calculating a voltage characteristic value according to the voltage estimation value and the current estimation value obtained by the sliding mode observer; The variable step-size hill climbing method is used to perform online optimization and tracking of the maximum value of the voltage characteristic quantity to achieve compensation for the estimated value of the rotor position angle.

2. A permanent magnet synchronous motor rotor position observation method according to claim 1, characterized in that: A sliding mode observer based on fast superhelical control theory is established, and the electrical angular velocity estimation value and the rotor position angle estimation value of the PMSM are obtained by the sliding mode observer, including: According to the PMSM voltage equation in the dq coordinate system, the PMSM current equation in the dq coordinate system is established; Constructing a sliding mode observer, and obtaining a current estimation value in a dq coordinate system through the sliding mode observer; A current error equation is established based on a sliding mode observer and a PMSM current equation in a dq coordinate system, and a current observation error is calculated according to the current error equation; The current observation error is selected as the sliding surface; According to the fast superhelical control theory, the sliding mode control input V is designed. d and V q The control law of In the dq coordinate system, based on the sliding mode control input V d and V q The control law is used to obtain the observed value of back electromotive force; Based on the back EMF observations, the PMSM electrical angular velocity estimate and rotor position angle estimate are calculated.

3. A method for observing the rotor position of a permanent magnet synchronous motor according to claim 2, characterized in that: The PMSM voltage equation in the dq coordinate system is: In the formula, i d 、i q 、u d 、u q are the d-axis stator current, q-axis stator current, d-axis stator voltage and q-axis stator voltage in the dq coordinate system respectively; R s , L d , L q They are stator resistance, d-axis stator inductance and q-axis stator inductance respectively; ω e is the electrical angular velocity of the rotor; ψ f is the flux linkage produced by the permanent magnet; The PMSM current equation in the dq coordinate system is: In the formula, L represents the matrix coefficient; A represents the matrix variable; θ e Indicates the actual electrical angle; E d 、E q They are the d-axis back-EMF and q-axis back-EMF in the dq coordinate system respectively; The sliding mode observer is: In the formula, and are the estimated d-axis current and q-axis current in the dq coordinate system, V d and V q is the input of sliding mode control; The current error equation is: ； In the formula, and They represent the d-axis current observation error and the q-axis current observation error respectively; The sliding surface is: Where, s represents the sliding surface; s d and q They represent the d-axis sliding surface and the q-axis sliding surface respectively; The control law of sliding mode control inputs Vd and Vq is: Where k1, k2, k3 and k4 are control parameters; When the current estimation value in the dq coordinate system reaches the sliding surface, based on the sliding mode control input V d and V q The back electromotive force observation value obtained by the control law is expressed as: In the formula, and They are the d-axis back-EMF observation value and the q-axis back-EMF observation value in the dq coordinate system respectively; Based on the back EMF observations, the formulas for calculating the PMSM electrical angular velocity estimate and rotor position angle estimate are: In the formula, and They are the estimated electrical angular velocity and rotor position angle of the PMSM, respectively.

4. A permanent magnet synchronous motor rotor position observation method according to claim 1, characterized in that: The voltage characteristic quantity is calculated based on the estimated voltage and estimated current of the PMSM in the dq coordinate system.

5. A permanent magnet synchronous motor rotor position observation method according to claim 4, characterized in that: The PMSM estimated voltage equation is: In the formula, and They are the estimated d-axis voltage and q-axis voltage in the dq coordinate system respectively; and are the estimated d-axis current and q-axis current in the dq coordinate system respectively; Δθ e is the rotor position angle error value; i d 、i q , are the d-axis stator current and q-axis stator current in the dq coordinate system respectively; L d , L q are the d-axis stator inductance and the q-axis stator inductance respectively; ω e is the electrical angular velocity of the rotor; ψ f is the flux generated by the permanent magnet; R s Indicates the stator resistance.

6. A permanent magnet synchronous motor rotor position observation method according to claim 4, characterized in that: The calculation formula of voltage characteristic quantity δ is: In the formula, is the estimated value of the q-axis voltage in the dq coordinate system; is the estimated value of the q-axis current in the dq coordinate system; ω e is the electrical angular velocity of the rotor; ψ f is the flux generated by the permanent magnet; Δθ e is the rotor position angle error value; R s Indicates the stator resistance.

7. A permanent magnet synchronous motor rotor position observation method according to claim 1, characterized in that: The variable step-length hill climbing method is used to track the maximum value of the voltage characteristic quantity to achieve compensation for the estimated value of the rotor position angle. The calculation formula is: In the formula, Δθ e (k+1) is the compensation angle at time k+1; Δθ e (k) is the compensation angle at time k; Δθ cop is the compensation angle adjustment term; dδ(k) represents the characteristic value of the optimal change direction; dΔθ e (k) represents the characteristic value of the change direction of the compensation angle; C is the step coefficient; δ(k) is the characteristic value of the steady-state voltage of the motor q axis at time k; δ(k-1) is the characteristic value of the steady-state voltage of the motor q axis at time k-1; Δθ e (k-1) is the compensation angle at time k-1.

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