Permanent magnet synchronous motor full speed domain position sensorless control method and system

Abstract

The application relates to a permanent magnet synchronous motor full-speed domain position sensorless control method and system, which comprises the following steps: obtaining a reference voltage vector and a measured three-phase stator current in a stationary coordinate system; based on the reference voltage vector and the measured three-phase stator current, establishing a voltage model and a current model of an effective flux linkage; constructing a second-order flux linkage observer through the voltage model and the current model, which is used for calculating the effective flux linkage of the voltage model and introducing proportional correction for effective flux linkage boundary correction; according to the effective flux linkage, calculating an original angle, inputting the original angle into a second-order system phase-locked loop, outputting a rotor angle and an angular velocity, and performing park transformation on the rotor angle, which is used for implementing standard FOC current loop and speed loop control. The application realizes strong robustness position sensorless control from static to full speed.

Description

Technical Field

[0001] This invention relates to the field of power electronics and electrical drive technology, and in particular to a sensorless control method and system for a permanent magnet synchronous motor across the entire speed range. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used due to their high power density, high efficiency, and compact structure. To achieve high-performance field-oriented control (FOC), traditional solutions rely on mechanical sensors mounted on the motor shaft to obtain rotor position information.

[0003] However, sensors increase system cost and size and reduce reliability, so sensorless control technology has attracted much attention. Existing sensorless strategies are mainly divided into two categories: (1) signal injection-based methods, which utilize the salient polarity of the motor and work well at low / zero speeds, but generate audible noise and torque pulsation, and are not suitable for weakly salient polarity motors; (2) model methods based on back electromotive force (EMF) or flux observation, which are mature in the medium and high speed range, but their performance deteriorates at low speeds due to the small amplitude of EMF and low signal-to-noise ratio. In addition, inverter nonlinearity (such as dead zone effect) introduces current harmonics, which further interfere with low-speed observation. To broaden the operating range, a hybrid effective flux observer has been proposed, which combines the advantages of voltage model (high-speed robustness) and current model (low-speed stability). However, this method heavily relies on accurate motor parameters, especially stator resistance Rs. At low speeds (≤5% of rated speed), a small mismatch in Rs can lead to significant rotor position estimation errors, or even system instability.

[0004] Therefore, there is an urgent need for a new sensorless control scheme that can both inherit the wide speed range advantages of hybrid effective flux observers and overcome their excessive dependence on the accuracy of Rs parameters. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to provide a sensorless control method for permanent magnet synchronous motors across the entire speed range, thereby solving the following key problems in the prior art: high sensitivity to stator resistance Rs parameter mismatch, especially in the low-speed region; difficulty in stable operation under ultra-low speed (≤1% of rated speed) load conditions; and susceptibility to inverter nonlinearity and external load disturbances.

[0006] To achieve the above objectives, the present invention provides the following solution: A sensorless control method for a permanent magnet synchronous motor across the entire speed range includes: Get at rest Based on the reference voltage vector and the measured three-phase stator current in the coordinate system, a voltage model and a current model for the effective magnetic flux are established. A second-order flux linkage observer is constructed using the voltage model and the current model to calculate the effective flux linkage of the voltage model, and a scaling correction is introduced to correct the effective flux linkage boundary. Based on the effective flux linkage, the original angle is calculated, and the original angle is input into the second-order system phase-locked loop to output the rotor angle and angular velocity. The rotor angle is then subjected to Park transformation for implementing standard FOC current loop and speed loop control.

[0007] Optionally, establishing the voltage model of the effective magnetic flux includes: ; in, For the stator resistance Total disturbance caused by mismatch, inverter nonlinearity, and load mutation. To measure the three-phase stator current, For the reference voltage vector, For motor flux linkage.

[0008] Optionally, establishing the current model of the effective magnetic flux includes: ; in, For the effective flux linkage in the current model, , for Shaft inductor, It is a permanent magnet flux linkage. For rotor angle, This represents the d-axis current.

[0009] Optionally, constructing the second-order flux observer includes: ; in, For stator flux The estimate, To address overall integrated disturbances The estimate, For magnetic flux observation error, , For observer gain, For the reference voltage vector, To measure the three-phase stator current, This is the stator resistance.

[0010] Optionally, the observer gain includes: ; in, This is the preset ESO bandwidth.

[0011] Optionally, calculating the effective flux linkage of the voltage model includes: ; in, For stator flux The estimate, For effective magnetic flux, To measure the three-phase stator current, for Shaft inductance.

[0012] Optionally, introducing the proportional correction for effective flux linkage boundary correction includes: ; in, The effective flux linkage after limiting. For adjustment coefficients, for, The effective flux linkage estimated by the model, This is for limiting the flux linkage amplitude.

[0013] Optionally, calculating the original angle includes: ; in, Original angle, , for Effective flux linkage of the shaft.

[0014] To achieve the above objectives, the present invention also provides a sensorless control system for a permanent magnet synchronous motor across the entire speed range, comprising: The model building module is used to obtain the model at rest. Based on the reference voltage vector and the measured three-phase stator current in the coordinate system, a voltage model and a current model for the effective magnetic flux are established. The ESO module is used to construct a second-order flux linkage observer using the voltage model and the current model, to calculate the effective flux linkage of the voltage model, and to introduce a scaling correction for effective flux linkage boundary correction. The closed-loop control module is used to calculate the original angle based on the effective flux linkage, input the original angle into the second-order system phase-locked loop, output the rotor angle and angular velocity, and perform Park transformation on the rotor angle to implement standard FOC current loop and speed loop control.

[0015] The beneficial effects of this invention are as follows: Immunity to stator resistance mismatch: This invention fundamentally eliminates stator resistance mismatch by estimating and compensating for the total integrated disturbance through ESO. The effect of mismatch on low-speed position estimation, even within ±50%. It can still work stably under error conditions; Supports ultra-low speed load operation: This invention, combined with an effective flux boundary corrector, can achieve stable operation at 0.6% of rated speed and 30% of rated load, breaking through the low-speed limit of traditional methods; High robustness: This invention has excellent suppression capabilities against external disturbances such as load sudden changes and inverter dead zones; Simple structure and easy to implement: This invention only adds an ESO module and a simple boundary corrector to the traditional hybrid observer, with low computational burden and strong engineering practicality; Full-speed domain coverage: This invention successfully achieves sensorless control across the entire speed domain, seamlessly switching from stationary, low-speed, medium-high-speed to power generation / electric mode. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in 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.

[0017] Figure 1 This is a schematic diagram of the effective magnetic flux linkage vector relationship in an embodiment of the present invention; Figure 2 This is a block diagram of the rotor position estimator for a Type II system (T2S) according to an embodiment of the present invention; Figure 3 This is a block diagram of the ESO-based disturbance observer structure according to an embodiment of the present invention; Figure 4 This is a block diagram of a hybrid effective flux linkage observer according to an embodiment of the present invention; Figure 5 This is an architecture diagram of a sensorless control method for a permanent magnet synchronous motor across the entire speed range, according to an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] like Figure 5As shown, this embodiment discloses a sensorless control method for a permanent magnet synchronous motor across the entire speed range, including: acquiring the position of the motor while stationary. Based on the reference voltage vector and measured three-phase stator current in the coordinate system, voltage and current models of the effective flux linkage are established. A second-order flux linkage observer is constructed using the voltage and current models to calculate the effective flux linkage of the voltage model, and proportional correction is introduced for effective flux linkage boundary correction. According to the effective flux linkage, the original angle is calculated, and the original angle is input into the second-order system phase-locked loop to output the rotor angle and angular velocity. The rotor angle is then subjected to Park transformation for implementing standard FOC current loop and speed loop control.

[0021] Specifically, this embodiment discloses a sensorless control method for a permanent magnet synchronous motor in the full speed domain, including: constructing a hybrid effective flux linkage model based on the effective flux linkage vector relationship, and then combining the obtained voltage model and current model to form a second-order flux linkage observer; An extended state observer (ESO) is used to estimate and compensate for the total system disturbance, which is used to suppress the flux estimation error caused by stator resistance Rs variation and inverter nonlinearity. Furthermore, using the effective flux linkage as the state variable and the reference stator voltage as the input, the flux linkage and total disturbance compensation are estimated through the ESO output. The total disturbance includes nonlinear factors such as stator resistance Rs variation, motor model parameter uncertainty, inverter dead zone and switching voltage drop.

[0022] Furthermore, an active flux boundary corrector is introduced during flux estimation. When the speed is lower than a set threshold, the estimated flux is corrected according to the flux amplitude limit function to prevent flux deviation and divergence. The active flux amplitude limit is set to 1.15 times the estimated flux steady-state amplitude. Furthermore, the control system adopts a unified structure that remains consistent across different speed ranges. Only the ESO parameters and the corrector gain are adaptively adjusted with speed. The position signal calculated from the effective flux linkage is subjected to secondary filtering and enhancement through a T2S position estimation structure to improve noise immunity and dynamic performance.

[0023] Furthermore, the constructed ESO disturbance compensation amount and the output of the hybrid effective flux linkage model are used together in the motor rotor position estimation module to achieve high-precision angle and speed estimation.

[0024] In one embodiment, this invention proposes a hybrid effective flux observer based on an extended state observer (ESO). Its core idea is to treat the combined disturbances caused by Rs mismatch, inverter nonlinearity, load abrupt changes, etc., as a "total disturbance," and utilize the ESO to estimate and compensate for it in real time, thereby making the system immune to changes in the total disturbance. Specifically, this includes the following steps: Step 1: Construct a basic hybrid effective flux observer, such as Figure 1 As shown: at rest In the coordinate system, based on the reference voltage vector and measured three-phase stator current We establish voltage and current models for the effective flux linkage, respectively: Voltage model (including unknown disturbances): ; in, Representative by Total disturbance caused by mismatch, inverter nonlinearity, load mutation, etc.

[0025] Current model (based on rotor angle estimated in the previous cycle) ): ; in, It is a permanent magnet flux linkage. , for Shaft inductor, This represents the effective flux linkage in the current model.

[0026] The outputs of the two models are fused through a PI controller to form a closed-loop observer.

[0027] Step 2: Design and integrate an Extended State Observer (ESO) for disturbance compensation: The system is modeled as follows: ; in, for The derivative of the state variable ,enter , .

[0028] like Figure 3 As shown, the second-order ESO is constructed as follows: ; in, Stator flux The estimate, Overall integrated disturbance The estimate, This is the flux linkage observation error. Observer gain. , Based on the preset ESO bandwidth Decide: ; Step 3: Form a robust effective flux linkage estimate: Stator flux estimated using ESO Calculate the effective flux linkage of the voltage model: ; because It already includes the disturbance Compensation, therefore right It is not sensitive to changes.

[0029] Step 4: Implement effective flux linkage boundary correction: In the ultra-low speed region (e.g., ≤100 rpm), to prevent flux linkage divergence, a simple proportional correction is introduced: ; in, It is a flux linkage amplitude limitation. It is the adjustment coefficient.

[0030] Step 5: Extract rotor position and speed and implement closed-loop control: Calculate the original angle: ;in, , for Effective flux linkage of the shaft.

[0031] like Figure 2 As shown, The input is fed into a Type-2 System (T2S) phase-locked loop, which outputs a smooth, high-precision final rotor angle. and angular velocity ; use Perform a Park transformation to complete standard FOC current loop and velocity loop control, resulting in a hybrid effective flux observer, such as... Figure 4 As shown.

[0032] This embodiment also provides a sensorless control system for a permanent magnet synchronous motor across the entire speed domain, including: a model building module for acquiring position data at rest. The reference voltage vector and measured three-phase stator current in the coordinate system are used to establish voltage and current models for the effective flux linkage. The ESO module is used to construct a second-order flux linkage observer using the voltage and current models, calculate the effective flux linkage of the voltage model, and introduce proportional correction for effective flux linkage boundary correction. The closed-loop control module is used to calculate the original angle based on the effective flux linkage, input the original angle into the second-order system phase-locked loop, output the rotor angle and angular velocity, and perform Park transformation on the rotor angle for implementing standard FOC current loop and speed loop control.

[0033] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A sensorless control method for a permanent magnet synchronous motor across its entire speed range, characterized in that, include: Get at rest Based on the reference voltage vector and the measured three-phase stator current in the coordinate system, a voltage model and a current model for the effective magnetic flux are established. A second-order flux linkage observer is constructed using the voltage model and the current model to calculate the effective flux linkage of the voltage model, and a scaling correction is introduced to correct the effective flux linkage boundary. Based on the effective flux linkage, the original angle is calculated, and the original angle is input into the second-order system phase-locked loop to output the rotor angle and angular velocity. The rotor angle is then subjected to Park transformation for implementing standard FOC current loop and speed loop control.

2. The sensorless control method for a permanent magnet synchronous motor across the entire speed range according to claim 1, characterized in that, Establishing the voltage model of the effective flux linkage includes: ； in, For the stator resistance Total disturbance caused by mismatch, inverter nonlinearity, and load mutation. To measure the three-phase stator current, For the reference voltage vector, For motor flux linkage.

3. The sensorless control method for a permanent magnet synchronous motor across the entire speed range according to claim 1, characterized in that, The current model for establishing the effective flux linkage includes: ； in, For the effective flux linkage in the current model, , for Shaft inductor, It is a permanent magnet flux linkage. For rotor angle, This represents the d-axis current.

4. The sensorless control method for a permanent magnet synchronous motor across the entire speed range according to claim 1, characterized in that, Constructing the second-order flux linkage observer includes: ； in, For stator flux The estimate, To address overall integrated disturbances The estimate, For magnetic flux observation error, , For observer gain, For the reference voltage vector, To measure the three-phase stator current, This is the stator resistance.

5. The sensorless control method for a permanent magnet synchronous motor across the entire speed range according to claim 4, characterized in that, The observer gain includes: ； in, This is the preset ESO bandwidth.

6. The sensorless control method for a permanent magnet synchronous motor across the entire speed range according to claim 1, characterized in that, Calculating the effective flux linkage of the voltage model includes: ； in, For stator flux The estimate, For effective magnetic flux, To measure the three-phase stator current, for Shaft inductance.

7. The sensorless control method for a permanent magnet synchronous motor across the entire speed range according to claim 1, characterized in that, Introducing the aforementioned proportional correction for effective flux linkage boundary correction includes: ； in, The effective flux linkage after limiting. For adjustment coefficients, for, The effective flux linkage estimated by the model, This is for limiting the flux linkage amplitude.

8. The sensorless control method for a permanent magnet synchronous motor across the entire speed range according to claim 1, characterized in that, Calculating the original angle includes: ； in, Original angle, , for Effective flux linkage of the shaft.

9. A sensorless control system for a permanent magnet synchronous motor across the entire speed range, implemented according to the method described in claims 1-8, characterized in that, include: The model building module is used to obtain the model at rest. Based on the reference voltage vector and the measured three-phase stator current in the coordinate system, a voltage model and a current model for the effective magnetic flux are established. The ESO module is used to construct a second-order flux linkage observer using the voltage model and the current model, to calculate the effective flux linkage of the voltage model, and to introduce a scaling correction for effective flux linkage boundary correction. The closed-loop control module is used to calculate the original angle based on the effective flux linkage, input the original angle into the second-order system phase-locked loop, output the rotor angle and angular velocity, and perform Park transformation on the rotor angle to implement standard FOC current loop and speed loop control.

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