A method, system and device for permanent magnet synchronous motor rotor position estimation

Abstract

The application relates to a permanent magnet synchronous motor rotor position estimation method, system and device, which realizes observation of a permanent magnet synchronous motor rotor position based on a cascaded nonlinear PI observer, and comprises the following steps: obtaining currents through current sensors on windings of the permanent magnet synchronous motor; obtaining stator current components through calculation; constructing a first-stage nonlinear PI observer based on the stator current components at a current sampling moment, and obtaining back electromotive force observation values; constructing a position observation error phase detector based on the back electromotive force observation values at the current sampling moment; constructing a second-stage nonlinear PI observer based on rotor electric angle observation errors at the current sampling moment, and obtaining rotor electric angular velocity observation values; and calculating rotor electric angle observation values at the current sampling moment based on the rotor electric angular velocity observation values at the current sampling moment, so as to realize rotor position estimation. Compared with the prior art, the application improves the dynamic performance of rotor position identification and reduces speed fluctuation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of permanent magnet synchronous motor rotor position estimation, in particular to a permanent magnet synchronous motor rotor position estimation method and system. BACKGROUND

[0002] Considering the cost problem and the need of real engineering, the position sensorless control of permanent magnet synchronous motor has become a research hotspot. The realization principle of position sensorless is mainly to obtain some electrical signals in the winding of permanent magnet synchronous motor, and to realize the estimation of rotor position and speed by using a specific control algorithm. The traditional control strategy based on sliding mode observer and phase-locked loop has the following shortcomings:

[0003] 1. By using continuous functions or saturation functions to replace discontinuous terms to suppress chattering phenomenon, such as a Chinese patent application No. CN202010841676.9 discloses a high-speed permanent magnet synchronous motor sensorless control system and method based on low-chattering sliding mode observer, and the literature (Zhang Jun, et al. A permanent magnet synchronous motor speed chattering suppression method based on optimized SMO [J]. Micro-motor, 2021, 54(10).). This method replaces the switching function in the sliding mode observer with a continuous function or a saturation function, although it reduces the chattering phenomenon, but the dynamic performance of the controller and the robustness to the parameters of the permanent magnet synchronous motor are not very prominent.

[0004] 2. The traditional sliding mode observer based on phase-locked loop uses PI controller as loop filter, and the dynamic performance is poor, such as the literature (Zuo Yun, et al. Speed sensorless control of traction motor based on improved q-PLL [J]. Proceedings of the Chinese Electrical Engineering Society, 2021, 41(01).), which introduces p component to propose a compensation scheme as an open-loop compensator to realize accurate speed tracking when the frequency slope changes. Although the previous stage uses a flux observer, the identified speed fluctuation is still relatively large.

[0005] In summary, the traditional control method combining sliding mode observer and phase-locked loop has the problem of poor dynamic performance of permanent magnet synchronous motor speed and position information, and cannot converge quickly. In addition, the traditional sliding mode algorithm has high-frequency chattering phenomenon, which usually needs to add a low-pass filter to avoid this problem, but this will cause the phase lag of rotor position estimation. Therefore, it is an urgent problem to design a method that can reduce speed fluctuation and make speed and rotor position converge quickly. SUMMARY

[0006] The purpose of the present application is to provide a permanent magnet synchronous motor rotor position estimation method, system and device to overcome the defects of the prior art.

[0007] The purpose of the present application can be achieved by the following technical solutions:

[0008] A permanent magnet synchronous motor rotor position estimation method, comprising the following steps:

[0009] 1) Select the permanent magnet synchronous motor to be observed;

[0010] 2) Obtain the current through the current sensor on the winding of the permanent magnet synchronous motor; based on the current, calculate the stator current component;

[0011] 3) Based on the stator current component, obtain the stator current component at the current sampling time, construct a first-order nonlinear PI observer, and obtain the back-EMF observation value at the current sampling time;

[0012] 4) Based on the back-EMF observation value at the current sampling time, construct a position observation error phase detector to obtain the rotor electrical angle observation error at the current sampling time;

[0013] 5) Based on the rotor electrical angle observation error at the current sampling time, construct a second-order nonlinear PI observer to obtain the rotor electrical angular velocity observation value at the current sampling time;

[0014] 6) Based on the rotor electrical angular velocity observation value at the current sampling time, calculate the rotor electrical angle observation value at the current sampling time, thereby realizing rotor position estimation.

[0015] Further, through the current sensor on the winding of the permanent magnet synchronous motor, the current is obtained, and based on the current, the stator current component is calculated, which specifically comprises:

[0016] The A-phase current i a and the B-phase current i b are obtained through the current sensors on the A-phase and B-phase windings of the permanent magnet synchronous motor;

[0017] According to the Clarke transformation, the stator current components i a and i β in the alpha-beta coordinate system are calculated respectively.

[0018] Further, based on the stator current components i a and i β , the stator current component ia,t and i β,t , a first nonlinear PI observer Φ1 is constructed, and its expression is:

[0019]

[0020] wherein u a,t , u β,t are the stator voltage components in the α, β coordinate system at the current sampling time t, are the observed values of the stator current components in the α, β coordinate system at the current sampling time t, k1 and k2 are the gain coefficients of the first nonlinear observer, are the back EMF observed values in the α, β coordinate system at the last sampling time t-1, are the back EMF observed values in the α, β coordinate system at the current sampling time t, R is the stator resistance, L d is the stator inductance, and T s is the sampling period.

[0021] Further, based on the back EMF observed values in the α, β coordinate system at the current sampling time t , a position observation error phase detector is constructed, and its expression is:

[0022]

[0023] wherein ε t is the rotor electrical angle observation error at the current sampling time t, is the rotor electrical angle observed value at the last sampling time t-1.

[0024] Further, based on the rotor electrical angle observation error ε t at the current sampling time t, a second nonlinear PI observer Φ2 is constructed, and its expression is:

[0025]

[0026] wherein: is the rotor electrical angular velocity observed value at the current sampling time t, ε i is the rotor electrical angle observation error at the i th sampling time, and k3 and k4 are the gain coefficients of the second nonlinear PI observer.

[0027] Further, the gain coefficients k1 of the first nonlinear PI observer Φ1 and the gain coefficients k3 of the second nonlinear PI observer Φ2 are used to adjust the dynamic performance of the rotor electrical angle observation, and k1>0 and k3>0.

[0028] Further, the gain coefficient k2 of the first stage nonlinear PI observer Φ1 and the gain coefficient k4 of the second stage nonlinear PI observer Φ2 are used to adjust the steady state performance of the rotor electrical angle observation, and k2>0, k4>0.

[0029] Further, the rotor electrical angular velocity observation value at the current sampling time t is calculated based on the rotor electrical angular velocity observation value at the previous sampling time t-1 The rotor electrical angle observation value at the current sampling time t is calculated based on the rotor electrical angular velocity observation value at the current sampling time t The expression is:

[0030]

[0031] Wherein, The rotor electrical angle observation value at the previous sampling time t-1.

[0032] A permanent magnet synchronous motor rotor position estimation system comprises an input module, a cascaded nonlinear PI observer and an output module.

[0033] The cascaded nonlinear PI observer comprises a first stage nonlinear PI observer, a position observation error phase detector and a second stage nonlinear PI observer.

[0034] The input module is connected to the permanent magnet synchronous motor, and the input module, the cascaded nonlinear PI observer and the output module are sequentially connected.

[0035] A permanent magnet synchronous motor rotor position estimation device comprises a memory and a processor, the memory stores a computer program, and the processor can execute the above-mentioned permanent magnet synchronous motor rotor position estimation method by calling the program instructions.

[0036] Compared with the prior art, the present application has the following beneficial effects:

[0037] 1、The first stage nonlinear PI observer can filter out the high frequency signal of the back electromotive force, can significantly reduce the high frequency noise caused by the traditional sliding mode observer, and can also avoid the phase lag caused by filtering, thereby improving the observation accuracy of the rotor electrical angle.

[0038] 2、The second stage nonlinear PI observer is arranged, and the two nonlinear PI observers are cascaded, so that the rotor electrical angular velocity and the electrical angle of the permanent magnet synchronous motor can be estimated at the same time, the estimation ability of the time-varying signal is improved, the dynamic estimation performance of the rotor electrical angle is improved, and the speed fluctuation is reduced.

[0039] 3、The cascaded nonlinear PI observer rotor position estimation method proposed in the present application can improve the dynamic performance and steady state accuracy of speed tracking without changing the framework of the permanent magnet motor speed feedback control system. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a system structure diagram of the application;

[0041] Figure 2 is a permanent magnet synchronous motor rotor position estimation curve based on a traditional sliding mode observer and a phase-locked loop;

[0042] Figure 3 is a permanent magnet synchronous motor rotor position estimation curve based on a cascaded nonlinear PI observer;

[0043] Figure 4 is a permanent magnet synchronous motor speed tracking curve based on a cascaded nonlinear PI observer;

[0044] Figure 5 is a permanent magnet synchronous motor speed tracking curve based on a traditional sliding mode observer and a phase-locked loop. DETAILED DESCRIPTION

[0045] The application will be described in detail below in combination with the drawings and specific embodiments. The embodiments are implemented on the premise of the technical solution of the application, and detailed implementation modes and specific operation processes are given, but the protection scope of the application is not limited to the following embodiments.

[0046] As shown in Figure 1 , it is a whole structure diagram of a permanent magnet synchronous motor rotor position estimation system provided by the embodiment, which includes an input module, a cascaded nonlinear PI observer and an output module;

[0047] The cascaded nonlinear PI observer includes a first-stage nonlinear PI observer, a position observation error phase detector and a second-stage nonlinear PI observer; the input module is connected to the permanent magnet synchronous motor, and the input module, the cascaded nonlinear PI observer and the output module are sequentially connected.

[0048] In specific implementation, first, voltage and current signals are obtained by sampling through components on the permanent magnet synchronous motor, and the voltage and current signals are input to the first-stage nonlinear PI observer to filter high-frequency signals in the back electromotive force, and second, the processed signals are input to the second-stage nonlinear PI observer to obtain the rotor electric angle and the rotor electric angular velocity of the permanent magnet synchronous motor, so as to obtain the rotor position estimation value.

[0049] A permanent magnet synchronous motor rotor position estimation method includes the following steps:

[0050] 1) Select a permanent magnet synchronous motor to be observed;

[0051] 2) Obtain the current through a current sensor on the winding of the permanent magnet synchronous motor; based on the current, calculate the stator current component;

[0052] 3) Based on the stator current component, the stator current component at the current sampling time is obtained, a first-level nonlinear PI observer is constructed, and the back EMF observation value at the current sampling time is obtained;

[0053] 4) Based on the back EMF observation value at the current sampling time, a position observation error phase detector is constructed, and the rotor electric angle observation error at the current sampling time is obtained;

[0054] 5) Based on the rotor electric angle observation error at the current sampling time, a second-level nonlinear PI observer is constructed, and the rotor electric angular velocity observation value at the current sampling time is obtained;

[0055] 6) Based on the rotor electric angular velocity observation value at the current sampling time, the rotor electric angle observation value at the current sampling time is calculated, so as to realize the rotor position estimation.

[0056] As a preferred embodiment, the electrical parameters of the permanent magnet synchronous motor used in the present example are shown in Table 1:

[0057] Table 1 Electrical parameters of permanent magnet synchronous motor

[0058]

[0059]

[0060] In specific implementation, the following steps are included:

[0061] Step 1): Through the current sensors on the A-phase and B-phase windings of the permanent magnet synchronous motor, the A-phase and B-phase currents i a and i b are obtained; according to the Clarke transformation, the stator current components in the α, β coordinate system i a and i β are calculated.

[0062] Step 2): According to the stator current components i a,t and i β,t at the current sampling time t obtained in step 1), a first-level nonlinear PI observer Φ1 is constructed, and its expression is:

[0063]

[0064] Wherein: u a,t and u β,t are the stator voltage components in the α, β coordinate system at the current sampling time t, and i are the observation values of the stator current components in the α, β coordinate system at the current sampling time t, k1 and k2 are the gain coefficients of the first-level nonlinear observer, are the back EMF observation values in the α, β coordinate system at the previous sampling time t-1, is the back EMF observation value of the α, β coordinate system at the current sampling time t, R is the stator resistance, L d is the stator inductance; T s is the sampling period.

[0065] Step 3): according to the back EMF observation value of the α, β coordinate system at the current sampling time t obtained in step 2) The position observation error phase detector is constructed as follows:

[0066]

[0067] Wherein: ε t is the observation error of the rotor electrical angle at the current sampling time t, is the rotor electrical angle observation value at the last sampling time t-1.

[0068] Step 4): according to the rotor electrical angle observation error ε t at the current sampling time t obtained in step 3), a second nonlinear PI observer Φ2 is constructed as follows:

[0069]

[0070] Wherein: is the observation value of the rotor electrical angular velocity at the current sampling time t, ε i is the rotor electrical angle observation error at the i-th sampling time, k3 and k4 are the second observer gain coefficients.

[0071] Step 5): according to the observation value of the rotor electrical angular velocity at the current sampling time t obtained in step 4) the observation value of the rotor electrical angle at the current sampling time t is calculated as follows: The expression is as follows:

[0072]

[0073] Wherein: is the observation value of the rotor electrical angle at the last sampling time t-1. Combined with the observation value of the rotor electrical angular velocity and the observation value of the rotor electrical angle the rotor position estimation value can be obtained.

[0074] The gain coefficients k1 of the first nonlinear PI observer Φ1 and the gain coefficients k3 of the second nonlinear PI observer Φ2 are used to adjust the dynamic performance of the rotor electrical angle observation, and k1>0, k3>0, and the greater k1 and k3 are, the faster the convergence speed of the rotor electrical angle observation is;

[0075] The gain coefficient k2 of the first-stage nonlinear PI observer Φ1 and the gain coefficient k4 of the second-stage nonlinear PI observer Φ2 are used to adjust the steady-state performance of the rotor electrical angle observation. k2 > 0 and k4 > 0. The larger k2 and k4 are, the smaller the steady-state error of the rotor electrical angle observation.

[0076] The observer's parameter settings are shown in Table 2:

[0077] Table 2 Parameters of the Cascaded Nonlinear PI Observer

[0078]

[0079] Compared with the present invention, the parameter selection of the traditional sliding mode observer and phase-locked loop is shown in Table 3:

[0080] Table 3 Parameters of Traditional Sliding Mode Observer and Phase-Locked Loop

[0081]

[0082] The phase-locked loop PI controller is in the following form:

[0083]

[0084] The sliding mode observer takes the following form:

[0085]

[0086] The method of combining the traditional sliding mode observer with the phase-locked loop is existing technology and will not be described in detail here. It is only used as a comparison with the actual effect produced by the present invention.

[0087] like Figure 2 The figure shows the curves obtained by using the traditional sliding mode observer and phase-locked loop method for rotor position estimation of permanent magnet synchronous motor. The dashed line represents the reference value and the solid line represents the actual observed value. It can be found that there is a certain phase lag in the observed rotor electrical angle.

[0088] like Figure 3 The figure shows the curve obtained by using the rotor position estimation method of permanent magnet synchronous motor based on cascaded nonlinear PI observer of the present invention. The dashed line represents the reference value and the solid line represents the actual observed value. It can be found that the observed rotor electrical angle phase lag is very small.

[0089] Based on the rotor position observation results obtained in this embodiment, the following experimental conditions are designed: the desired speed is 100 r / min, and the speed is switched to 500 r / min at 1 second. At 4 seconds, a load disturbance is applied, and the observed value of the motor rotor electric angular velocity can be obtained.

[0090] Figure 4The chattering phenomenon in the speed tracking process of the permanent magnet synchronous motor under the permanent magnet synchronous motor rotor position estimation method based on the cascade nonlinear PI observer is shown, wherein the dashed line represents the reference value, and the solid line represents the actual observation value, and it can be found that the chattering of the permanent magnet synchronous motor is only about ±0.17r / min between 2 seconds and 3 seconds, and has good dynamic performance when the speed is switched.

[0091] Figure 5 The chattering phenomenon in the speed tracking process of the permanent magnet synchronous motor under the permanent magnet synchronous motor rotor position estimation method based on the traditional sliding mode observer and the phase-locked loop is shown, and it can be found that the chattering of the permanent magnet synchronous motor is about ±11r / min between 2 seconds and 3 seconds. Figure 5 And Figure 4 By comparison, it can be seen that when the permanent magnet synchronous motor rotor position estimation method based on the traditional sliding mode observer and the phase-locked loop is used, the fluctuation of the speed is larger, and the dynamic performance when the speed is switched is also poorer.

[0092] The embodiment also provides a permanent magnet synchronous motor rotor position estimation device, which comprises a memory and a processor, the memory stores a computer program, and the processor can execute the permanent magnet synchronous motor rotor position estimation method as above by calling program instructions.

[0093] The above describes the preferred embodiments of the present application in detail. It should be understood that those skilled in the art can make many modifications and changes without creative labor according to the concept of the present application. Therefore, any technical solution obtained by logical analysis, reasoning or limited experiment on the basis of the prior art according to the concept of the present application shall be within the protection scope defined by the claims.

Claims

1. A method for estimating the rotor position of a permanent magnet synchronous motor, characterized in that, Includes the following steps: Select the permanent magnet synchronous motor to be observed; The current is obtained through a current sensor on the winding of the permanent magnet synchronous motor; the stator current component is calculated based on the current. Based on the stator current components, the stator current components at the current sampling time are obtained, and a first-level nonlinear PI observer is constructed to obtain the back EMF observation value at the current sampling time. Based on the back EMF observation value at the current sampling time, a position observation error phase detector is constructed to obtain the rotor electrical angle observation error at the current sampling time. Based on the rotor electrical angle observation error at the current sampling time, a second-level nonlinear PI observer is constructed to obtain the rotor electrical angular velocity observation value at the current sampling time. Based on the observed rotor electrical angular velocity at the current sampling moment, the observed rotor electrical angle at the current sampling moment is calculated, thereby realizing rotor position estimation; The current is acquired through a current sensor on the winding of the permanent magnet synchronous motor, and the stator current component is calculated based on the current, specifically including: The current i in phase A is obtained by using current sensors on the A-phase and B-phase windings of the permanent magnet synchronous motor. a and B-phase current i b ; Based on the Clarke transform, the stator current components i in the α and β coordinate systems are calculated respectively. a i β ; Based on the stator current component i a andi β The stator current component i at the current sampling time t is obtained. a,t andi β,t Construct the first-level nonlinear PI observer Φ1, whose expression is: Where: u a,t u β,t These represent the stator voltage components in the α and β coordinate systems at the current sampling time t. , respectively, are the observed values ​​of the stator current components in the α and β coordinate systems at the current sampling time t, where k1 and k2 are the gain coefficients of the first-stage nonlinear observer. These are the back electromotive force observations in the α and β coordinate systems at the previous sampling time t-1. The back electromotive force is the observed value in the α and β coordinate system at the current sampling time t, where R is the stator resistance and L is the back electromotive force. d For stator inductance, T s The sampling period; Based on the back electromotive force observation values ​​in the α and β coordinate systems at the current sampling time t Construct a position observation error phase detector, the expression of which is: Where: ε t The rotor electrical angle observation error at the current sampling time t. This is the rotor electrical angle observation value at the previous sampling time t-1; Based on the rotor electrical angle observation error ε at the current sampling time t t Construct a second-level nonlinear PI observer Φ2, whose expression is: in: ε is the observed rotor electric angular velocity at the current sampling time t. i K represents the rotor electrical angle observation error at the i-th sampling time, and k3 and k4 are the gain coefficients of the second-stage nonlinear PI observer.

2. The method for estimating the rotor position of a permanent magnet synchronous motor according to claim 1, characterized in that, The gain coefficient k1 of the first-stage nonlinear PI observer Φ1 and the gain coefficient k3 of the second-stage nonlinear PI observer Φ2 are used to adjust the dynamic performance of rotor electrical angle observation, and k1 > 0, k3 > 0.

3. The method for estimating the rotor position of a permanent magnet synchronous motor according to claim 1, characterized in that, The gain coefficient k2 of the first-stage nonlinear PI observer Φ1 and the gain coefficient k4 of the second-stage nonlinear PI observer Φ2 are used to adjust the steady-state performance of the rotor electrical angle observation, and k2 > 0, k4 > 0.

4. The method for estimating the rotor position of a permanent magnet synchronous motor according to claim 1, characterized in that, Based on the observed rotor electric angular velocity at the current sampling time t Calculate the observed rotor electrical angle at the current sampling time t. Its expression is: in: This is the observed rotor electrical angle value at the previous sampling time t-1.

5. A rotor position estimation device for a permanent magnet synchronous motor, characterized in that, It includes a memory and a processor, the memory storing a computer program, and the processor calling the program instructions to execute the permanent magnet synchronous motor rotor position estimation method as described in any one of claims 1 to 4.

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