Permanent magnet synchronous motor mechanical parameter and electrical parameter identification method

Abstract

The application discloses a permanent magnet synchronous motor mechanical parameter and electrical parameter identification method, which comprises the following steps: performing nonlinear transformation on a steady-state model of the permanent magnet synchronous motor; performing parameter replacement on the steady-state model with eliminated nonlinear coefficients based on a torque equation and mechanical motion wear in combination with measured data under different rotating speeds; obtaining estimation and performing calculation and value taking; and substituting the obtained result into a motor model for estimating flux linkage to obtain estimated flux linkage and estimated electromagnetic torque. By using the application, the motor damping coefficient and DC bias can be accurately estimated, and motor flux linkage diagrams and electromagnetic torque diagrams that are closer to actual operation conditions of the motor can be obtained. The application can be widely applied to the technical field of permanent magnet synchronous motors as a permanent magnet synchronous motor mechanical parameter and electrical parameter identification method.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet synchronous motor technology, and in particular to a method for identifying the mechanical and electrical parameters of a permanent magnet synchronous motor. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) have been widely researched and applied in various industries due to their flexibility, controllability, and high torque density. In recent years, numerous PMSM control schemes have been proposed to meet the requirements of various applications. PMSM parameters are crucial for condition monitoring, fault detection, and speed control of PMSM systems, particularly in controller design and condition monitoring. Mechanical parameters, including inertial torque, viscous friction coefficient, load torque, and DC bias, play a key role in achieving high dynamic performance in speed control. Accurate estimation of these parameters is essential for obtaining high dynamic response performance and strong robustness. However, these parameters cannot be directly measured during actual motor operation and require estimation using precise motor models and reliable algorithms. For example, winding resistance easily changes with temperature, while the PMSM rotor flux linkage varies with temperature or magnetic density, and the inertial torque varies with the shape and size of the mechanical components. Therefore, there is currently no method that can accurately identify the parameters of a permanent magnet synchronous motor. Summary of the Invention

[0003] To address the aforementioned technical problems, the objective of this invention is to provide a method for identifying the mechanical and electrical parameters of a permanent magnet synchronous motor, which reduces the coupling between parameters and yields motor flux linkage diagrams and electromagnetic torque diagrams that more closely reflect the actual operating conditions of the motor.

[0004] The first technical solution adopted in this invention is: a method for identifying the mechanical and electrical parameters of a permanent magnet synchronous motor, comprising the following steps:

[0005] A nonlinear transformation is performed on the steady-state model of the permanent magnet synchronous motor to obtain the steady-state model of the permanent magnet synchronous motor after eliminating the nonlinear coefficients.

[0006] Based on the electromagnetic torque equation, the steady-state model of the permanent magnet synchronous motor after eliminating the nonlinear coefficient is replaced with parameters to obtain a new motor model;

[0007] Voltage data at different speeds are collected and input into a new motor model to eliminate irrelevant variables, resulting in a motor model for estimating electromagnetic torque.

[0008] Mechanical motion wear optimization was performed on the motor model for estimating electromagnetic torque to obtain equations for estimating damping coefficient and DC bias;

[0009] Multiple sets of voltage data at different speeds were collected and input into the equations for estimating the damping coefficient and DC bias to obtain the estimated damping coefficient and DC bias.

[0010] The steady-state model of the permanent magnet synchronous motor after eliminating the nonlinear coefficient is transformed into an equation, and combined with the electromagnetic torque equation and the mechanical motion equation, the motor model with estimated flux linkage is obtained.

[0011] Parameter estimation is performed based on the electromagnetic torque equation and the motor model for estimating flux linkage, and the estimation results are obtained.

[0012] Furthermore, the step of performing a nonlinear transformation on the steady-state model of the permanent magnet synchronous motor to obtain a steady-state model of the permanent magnet synchronous motor after eliminating nonlinear coefficients specifically includes:

[0013] To make the parameter estimation independent of the difficult-to-obtain rotor position, the steady-state model of the permanent magnet synchronous motor is rewritten using the short-time average value of the dq axis voltage;

[0014] By combining the dq-axis model of the motor, the nonlinear coefficients of the rewritten steady-state model of the permanent magnet synchronous motor are eliminated to avoid the approximation error introduced by the search method.

[0015] Furthermore, in the step of replacing the parameters of the steady-state model of the permanent magnet synchronous motor after eliminating the nonlinear coefficients based on the electromagnetic torque equation to obtain a new motor model, the expression of the electromagnetic torque equation is as follows:

[0016]

[0017] Where n p λ is the extreme logarithm. d , λ q represents the flux linkage in the dq axis.

[0018] Furthermore, the step of collecting voltage data at different speeds and inputting it into a new motor model for irrelevant variable elimination to obtain a motor model for estimating electromagnetic torque specifically includes:

[0019] Given a current, the voltages of the new motor model at two different speeds were collected;

[0020] By subtracting the new motor models at different speeds, the resistance and dead zone voltage that are independent of the speed in the model will be eliminated, and a motor model for estimating the electromagnetic torque will be obtained.

[0021] Furthermore, the step of optimizing the mechanical motion and wear of the motor model for estimating the electromagnetic torque to obtain the equations for estimating the damping coefficient and DC bias specifically includes:

[0022] The equation of motion for a motor considering mechanical wear is expressed as follows;

[0023] T e =T L +Bω m +C

[0024] Where B is the damping coefficient, C is the DC deflection, and ω m T is the mechanical angular velocity. L For load torque

[0025] Substituting the motor's mechanical motion equations, which take mechanical wear into the motor model for estimating electromagnetic torque, yields equations for estimating the damping coefficient and DC bias.

[0026] Furthermore, the step of collecting multiple sets of voltage data at different rotational speeds and inputting them into the equations for estimating the damping coefficient and DC bias to obtain the estimated damping coefficient and DC bias specifically includes:

[0027] The equations for estimating the damping coefficient and DC bias are generalized to enable voltage collection at multiple speeds.

[0028] Multiple sets of motor operating data at different speeds were collected, and the estimated damping coefficient and DC bias were calculated using the least squares method.

[0029] Furthermore, the step of performing equation transformation on the steady-state model of the permanent magnet synchronous motor after eliminating nonlinear coefficients, and combining the electromagnetic torque equation and the mechanical motion equation to obtain the motor model for estimating the flux linkage, specifically includes:

[0030] For the steady-state model of the permanent magnet synchronous motor after eliminating nonlinear coefficients, V d I d -V d I q =ω(λ) d I d +λ q I q Transform the expression into an equation so that the right side of the equation has λ. d I q -λ q I d This polynomial;

[0031] Combining the electromagnetic torque equation with λ d I q -λ q I d Replace with A motor model with estimated flux linkage is obtained.

[0032] Furthermore, the step of estimating parameters based on the electromagnetic torque equation and the motor model for estimating flux linkage to obtain the estimation result specifically includes:

[0033] Combining the mechanical motion equations of the motor that take into account the mechanical wear of the motor, T e Replace with T L +Bω m +C, so that the motor model for estimating the flux linkage includes the parameter damping coefficient and DC bias;

[0034] Substituting the estimated damping coefficient and DC deflection into the motor model containing the estimated flux linkage, the estimated flux linkage is obtained.

[0035] The electromagnetic torque is estimated using the estimated dq-axis flux linkage, and the result is compared with the load torque to verify its accuracy.

[0036] The beneficial effects of the method and system of this invention are as follows: This invention takes into account the influence of inverter nonlinearity, damping coefficient, and DC bias on motor parameters. By effectively eliminating the influence of inverter nonlinearity, the coupling between parameters is reduced, and the motor damping coefficient and DC bias are accurately estimated, thereby obtaining motor flux linkage diagram and electromagnetic torque diagram that are closer to the actual operating conditions of the motor. Moreover, this method does not require any additional sensors or signals to be injected into the machine for parameter estimation. By decoupling the estimation model, the cross-influence between parameters is effectively reduced, and the computational efficiency is improved. Attached Figure Description

[0037] Figure 1 This is a flowchart of the steps in the method for identifying the mechanical and electrical parameters of a permanent magnet synchronous motor according to the present invention;

[0038] Figure 2 This is a schematic diagram of the model conversion for the method of identifying mechanical and electrical parameters of permanent magnet synchronous motors according to the present invention;

[0039] Figure 3 This is a schematic diagram of the nonlinear coefficient trigonometric function of the method for identifying the mechanical and electrical parameters of a permanent magnet synchronous motor according to the present invention. Detailed Implementation

[0040] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only for ease of explanation and do not limit the order of the steps. The execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.

[0041] Reference Figure 1 and Figure 2 This invention provides a method for identifying the mechanical and electrical parameters of a permanent magnet synchronous motor, the method comprising the following steps:

[0042] S1. Perform a nonlinear transformation on the steady-state model of the permanent magnet synchronous motor to obtain the steady-state model of the permanent magnet synchronous motor after eliminating the nonlinear coefficients.

[0043] S1.1 The expression for the steady-state model of the permanent magnet motor considering the nonlinearity of the voltage inverter is as follows:

[0044]

[0045] Where u d u q i d i q L d L q , λ d , λ q These represent the voltage, current, inductance, and flux linkage on the dq axis, respectively, and ω. r R is the rotor electrical speed, R is the winding resistance, and D is the rotor electrical speed. d V dead and D q V dead It is the distortion voltage of the dq axis inverter, V dead The distortion parameter D is caused by the dead-time effect. d and D q The coefficients are nonlinear, and D d and D q The expression is as follows:

[0046]

[0047] Where int{x} is a function that takes the closest integer value, and γ is the current angle, with tan(γ) = -i d / i q θ depends on the rotor position.

[0048] S1.2 From (2), we know that the steady-state model of the permanent magnet motor involves the rotor position θ. Under a fixed current, the dq-axis voltage changes periodically with the rotor position. In order to make the parameter estimation independent of the difficult-to-obtain rotor position, we use v d / q The short-time average value is used to rewrite the steady-state model of the permanent magnet motor. The rewritten steady-state model expression of the permanent magnet motor is as follows:

[0049]

[0050] Where V d V q I d I q , u in multiple electrical cycles d u q i d iq D d D q The average value; after taking the average value, It is independent of the rotor position and depends only on the current angle.

[0051] S1.3、 Since γ is nonlinear, it can be calculated in parameter estimation using (2). The value is [value], however, the operation is simple but requires a large computational cost, and it can also be [value]. Creating a lookup table is an option, but this method inevitably introduces approximation errors, affecting the accuracy of parameter estimation. Therefore, a motor dq-axis model is used to eliminate nonlinear coefficients. The effect is determined by multiplying I by the two equations in (3) respectively. d I q The following expression is obtained:

[0052]

[0053] S1.4, dq-axis current I d I q It can be regarded as the stator current I s A function of the current angle γ:

[0054] I d =-I s sinγ, I q =I s cosγ (6)

[0055] Where γ∈[0°, 90°],

[0056] Substituting (6) into (4) and (5), and performing addition and subtraction operations on the two resulting expressions, we obtain the following expressions:

[0057]

[0058] S1.4, such as Figure 3 As shown, you can see make Equation (7) can be rewritten as the steady-state model of the permanent magnet synchronous motor after eliminating the nonlinear coefficients, as shown in the following expression:

[0059]

[0060] Where ω is the rotor electric speed and c is a constant.

[0061] S2. Based on the electromagnetic torque equation, the steady-state model of the permanent magnet synchronous motor after eliminating the nonlinear coefficient is replaced with parameters to obtain a new motor model;

[0062] S2.1 The expression for the electromagnetic torque equation is as follows:

[0063]

[0064] Where n p λ is the extreme logarithm. d , λ q represents the flux linkage in the dq axis.

[0065] S2.2, Substitute (10) into (8) to get λ d I q -λ d I q Replace with The new motor model is obtained, and its expression is as follows:

[0066]

[0067] S3. Collect voltage data at different speeds and input them into the new motor model to eliminate irrelevant variables and obtain a motor model for estimating electromagnetic torque;

[0068] S3.1, For a given current condition {I} d I q Voltage measurement {V} di V qi} can be at two different speeds {ω i}, i∈[0,1] are collected, and according to equation (11), the expression is as follows,

[0069]

[0070] S3.2, Let With i∈[0,1], eliminating the consideration of resistance and dead zone voltage in the model, equation (12) can be transformed into a motor model for estimating electromagnetic torque, as shown in the following expression:

[0071]

[0072] Where ω1 and ω0 are different rotor electrical speeds, V d1 V q1 The voltage value, V, was measured at rotational speed ω1. d0 V q0 The voltage value was measured at a rotational speed of ω0.

[0073] S4. Perform mechanical motion wear optimization on the motor model for estimating electromagnetic torque to obtain the equations for estimating damping coefficient and DC bias;

[0074] S4.1 The mechanical motion equation of the motor considering mechanical wear is expressed as follows:

[0075] T e =T L +Bω m +C (14)

[0076] Where B is the damping coefficient, C is the DC deflection, and ω m T is the mechanical angular velocity. L This represents the load torque.

[0077] S4.2. To estimate the damping coefficient and DC deflection, substitute (14) into (12), and assume... For i∈[0,1], we get the following expression:

[0078]

[0079] S4.3. Combining (15) and (16) to eliminate x, that is, to eliminate the consideration of resistance and dead zone voltage in the model, the equations for estimating the damping coefficient and DC bias are as follows:

[0080]

[0081] S5. Collect multiple sets of voltage data at different speeds and input them into the equations for estimating the damping coefficient and DC bias to calculate the estimated damping coefficient and DC bias.

[0082] S5.1, Assume that for a given dq current {I} d I q Voltage data is collected at K+1 speeds, where the speeds are ω0, ..., ω k , where ω k =ω+kΔω, k=0,1,2,…,K, set the dq axis voltage as {u dk u qk , k = 0, 1, 2, ..., K}.

[0083] S5.2. Generalizing equation (17) yields the following expression:

[0084]

[0085] S5.3. Take multiple sets of motor operating data at different speeds, and calculate the damping coefficient B and DC bias C using the least squares method. The calculation expressions are as follows:

[0086]

[0087] Where X1 = [BC] T ,

[0088]

[0089] S6. Perform equation transformation on the steady-state model of the permanent magnet synchronous motor after eliminating the nonlinear coefficient, and combine the electromagnetic torque equation and the mechanical motion equation to obtain the motor model with estimated flux linkage.

[0090] S6.1. Transform equation (9) in the steady-state model of the permanent magnet synchronous motor after eliminating the nonlinear coefficient, and multiply both sides by I. q Then add or subtract on the right side of the equation simultaneously. Polynomials, extracting common factors to make the right side of the equation have λ. d I q -λ q I d This polynomial; then multiply both sides of equation (9) by I. d Then add or subtract on the right side of the equation simultaneously. Polynomials, extracting common factors to make the right side of the equation have λ. q I q -λ q I d This polynomial;

[0091] S6.2, Combining the electromagnetic torque equation (10) with λ d I q -λ q I d Replace with The motor model with estimated flux linkage is obtained, and its expression is shown below:

[0092]

[0093] S7. Based on the electromagnetic torque equation and the motor model for estimating the flux linkage, perform parameter estimation to obtain the estimation results;

[0094] S7.1, Combining the motor mechanical motion equations that take into account motor mechanical wear, T e Replace with T L +Bω m With +C, the motor model for estimating the flux linkage now includes the parameter damping coefficient and DC bias, as shown in the following expression:

[0095]

[0096] S7.2 Substitute the estimated damping coefficient and DC deflection into equation (21) to verify the accuracy of the dq flux linkage;

[0097] S7.3 The flux linkage can be estimated from the following expression:

[0098]

[0099] Where X2=[λ q ], X3=[λ d ],

[0100]

[0101]

[0102] S7.4, Using the estimated dq-axis flux linkage λ d , λ q According to the electromagnetic torque equation (10), the electromagnetic torque is estimated and compared with the load torque to verify the accuracy of the result.

[0103] The content of the above method embodiments is applicable to this system embodiment. The specific functions implemented in this system embodiment are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.

[0104] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A method for identifying the mechanical and electrical parameters of a permanent magnet synchronous motor, characterized in that, Includes the following steps: A nonlinear transformation is performed on the steady-state model of the permanent magnet synchronous motor to obtain the steady-state model of the permanent magnet synchronous motor after eliminating the nonlinear coefficients. Based on the electromagnetic torque equation, the steady-state model of the permanent magnet synchronous motor after eliminating the nonlinear coefficient is replaced with parameters to obtain a new motor model; Voltage data at different speeds are collected and input into a new motor model to eliminate irrelevant variables, resulting in a motor model for estimating electromagnetic torque. Mechanical motion wear optimization was performed on the motor model for estimating electromagnetic torque to obtain equations for estimating damping coefficient and DC bias; Multiple sets of voltage data at different speeds were collected and input into the equations for estimating the damping coefficient and DC bias to obtain the estimated damping coefficient and DC bias. The steady-state model of the permanent magnet synchronous motor after eliminating the nonlinear coefficient is transformed into an equation, and combined with the electromagnetic torque equation and the mechanical motion equation, the motor model with estimated flux linkage is obtained. Parameter estimation is performed based on the electromagnetic torque equation and the motor model with estimated flux linkage to obtain the estimation results; The steady-state model of the permanent magnet synchronous motor after eliminating the nonlinear coefficient is expressed by the following formula: in , , , In multiple electrical cycles , , , The average value, where R is the winding resistance. For stator current, The rotor's electrical speed, The distortion parameter is caused by the dead zone effect. , The flux linkage in the dq axis. For constant terms; The formula for the new motor model is as follows: in , , , In multiple electrical cycles , , , The average value, where R is the winding resistance. For stator current, The rotor's electrical speed, The electromagnetic torque of the motor. The distortion parameter is caused by the dead zone effect. For extreme logarithms, For constant terms; The motor model for estimating electromagnetic torque is expressed by the following formula: in For extreme logarithms, The electromagnetic torque of the motor. , For different rotor electrical speeds, , for Voltage values ​​measured at rotational speed for Voltage values ​​measured at rotational speed , In multiple electrical cycles The average value; The equations for estimating the damping coefficient and DC bias are expressed as follows: Where B is the damping coefficient and C is the DC bias. for Load torque at rotational speed, Load torque at rotational speed, , for Voltage values ​​measured at rotational speed for Voltage values ​​measured at rotational speed , In multiple electrical cycles , The average value, It is an extreme logarithm.

2. The method for identifying mechanical and electrical parameters of a permanent magnet synchronous motor according to claim 1, characterized in that, The step of performing a nonlinear transformation on the steady-state model of the permanent magnet synchronous motor to obtain a steady-state model of the permanent magnet synchronous motor after eliminating the nonlinear coefficients specifically includes: The steady-state model of the permanent magnet synchronous motor is rewritten using the short-time average value of the dq axis voltage; The nonlinear coefficients of the rewritten steady-state model of the permanent magnet synchronous motor are eliminated to obtain the steady-state model of the permanent magnet synchronous motor after the nonlinear coefficients are eliminated.

3. The method for identifying mechanical and electrical parameters of a permanent magnet synchronous motor according to claim 1, characterized in that, The step of collecting multiple sets of voltage data at different speeds and inputting them into equations for estimating the damping coefficient and DC bias to obtain the estimated damping coefficient and DC bias specifically includes: The equations for estimating the damping coefficient and DC bias are generalized. Multiple sets of motor operating data at different speeds were collected, and the estimated damping coefficient and DC bias were calculated using the least squares method.

4. The method for identifying mechanical and electrical parameters of a permanent magnet synchronous motor according to claim 1, characterized in that, The motor model for estimating the flux linkage is expressed by the following formula: in , , , In multiple electrical cycles , , , The average value, For stator current, The rotor's electrical speed, For extreme logarithms, , The flux linkage in the dq axis. This represents the electromagnetic torque of the motor.

Images