Permanent magnet synchronous motor parameter identification method, recording medium and system

Abstract

The invention belongs to the technical field of motor control, and particularly relates to a parameter identification method of a permanent magnet synchronous motor, which solves the problem of rank deficiency of identification equations by increasing the number of parameter identification equations by adding a high-frequency sinusoidal current instruction signal and adding an additional excitation signal on the basis of an original current instruction. Compared with an existing method, the complexity and the operand of a control system are reduced, and the control efficiency is improved; the identification result error caused by the dead zone effect and the rotating speed harmonic wave is additionally calculated and compensated, and the identification result precision is improved; the built-in permanent magnet synchronous motor is ensured to stably operate in various environments, and the method is suitable for controlling the permanent magnet synchronous motor with frequently fluctuating working conditions. The invention also provides a non-transitory readable recording medium storing the program of the method and a system comprising the medium, and the program can be called through a processing circuit to execute the method.

Description

Technical Field

[0001] The invention belongs to the technical field of motor control and discloses a permanent magnet synchronous motor parameter identification method, a recording medium and a system. Background Art

[0002] Built-in permanent magnet synchronous motors are widely used in electric vehicles, servo systems, wind power generation and other industrial fields due to their strong dynamic performance and high torque density. During the operation of built-in permanent magnet synchronous motors, obtaining accurate motor parameters plays an important role in motor operation status monitoring, motor fault diagnosis and high-performance control. Electrical parameters include quadrature-axis inductance, direct-axis inductance, stator resistance and permanent magnet flux. The quadrature-axis inductance will change significantly with the change of magnetic circuit saturation, and the stator resistance will change due to the influence of ambient temperature. Therefore, the parameter identification of built-in permanent magnet synchronous motors needs to be performed in real time.

[0003] However, there is a common problem in the existing online parameter identification methods for built-in permanent magnet synchronous motors, that is, the parameter identification equations are rank-deficient, and accurate identification results of all parameters cannot be obtained at the same time. The parameter identification methods currently proposed have not completely solved the rank-deficient problem of the parameter identification equations. They can only identify some parameters or only obtain locally converged parameter identification results, and the obtained parameter identification results cannot be verified for accuracy in real time. Therefore, while the built-in permanent magnet synchronous motor is running at high performance, how to effectively deal with the rank-deficient problem of the parameter identification equations to obtain accurate online parameter identification results and verify the accuracy of the parameter identification results in real time is a problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0004] In view of the above problems, the present invention provides a method for identifying parameters of a permanent magnet synchronous motor, comprising the following steps:

[0005] S1. Add a high-frequency current command to the current control loop, and superimpose the high-frequency sinusoidal current command values ​​on the d-axis and q-axis basic current reference values ​​obtained from the speed control loop to obtain the d-axis and q-axis current command values ​​after stimulation;

[0006] S2. Run the deadbeat predictive control by using the motor parameters given before adding the high-frequency current, and establish a simplified voltage discrete equation of the built-in permanent magnet synchronous motor in the dq rotating coordinate system; collect relevant data and substitute them into the simplified voltage discrete equation, wherein the relevant data includes the real-time current and speed measurement results of the built-in permanent magnet synchronous motor and the command current after adding the high-frequency command signal, and obtain the current round command voltage;

[0007] S3. Extract the cosine function of the high-frequency current command phase angle, multiply the double cosine function by the current round command voltage, and then filter it through a low-pass filter to obtain the modulated voltage value. Use the modulated voltage value to obtain the inductance, stator resistance and flux linkage to complete the current round of parameter identification, and feed the identified motor parameters back to the deadbeat predictive control algorithm for the next round of parameter identification;

[0008] S4. Verify the accuracy of each parameter identification result based on the changes in the d-axis component and the q-axis component of the measured current. If the accuracy meets the standard, stop adding the high-frequency current command and complete the parameter identification.

[0009] Preferably, the frequency of the added high-frequency current command avoids selecting 6 times of the motor operating frequency and an integer multiple of 6.

[0010] Preferably, the speed measurement result is corrected by a pre-designed notch filter transfer function, and the notch filter transfer function is as follows:

[0011]

[0012] Where k1 and k2 are proportional constants of the notch filter, ω ef is the measured motor speed, ω e is the motor speed after filtering, s represents the complex variable in Laplace transform, ω hd is the frequency of the injected d-axis high-frequency current, ω hq is the frequency of the injected q-axis high-frequency current.

[0013] Preferably, step S3 also includes correcting the parameter identification error caused by the dead zone effect of the converter, and the specific steps are as follows:

[0014] Calculate the high frequency voltage error caused by the dead zone effect:

[0015]

[0016] Where R ah , R ah and R ah The resistance error of three phases A, B and C caused by the high frequency voltage generated by the dead zone effect, i dh is the actual DC current of the direct axis, i qh is the actual DC current of the quadrature axis, θ r is the rotor position angle, and the three-phase resistance error is: ΔU is the phase voltage error, k is the error constant;

[0017] The stator resistance identification error considering the dead zone effect error is:

[0018]

[0019] Where, LPF{} represents the result after filtering by a low-pass filter, and the low-pass filter selects a second-order Butterworth low-pass filter;

[0020] Subtracting the stator resistance identification error from the stator resistance identification result to obtain a corrected stator resistance identification value;

[0021] Calculate the permanent magnet flux correction value after considering the dead zone effect error:

[0022]

[0023] In the formula, is the DC value of the direct-axis command voltage, is the DC value of the quadrature-axis command voltage, is the direct-axis inductance identification result, is the identification result of the quadrature-axis inductance, i df is the actual DC current of the direct axis, i qf is the actual DC current of the quadrature axis, ω e is the rotor electrical angular velocity.

[0024] Another solution of the present invention is to provide a non-transitory readable recording medium for storing one or more programs including a plurality of instructions. When the instructions are executed, the processing circuit will execute the above-mentioned method for identifying parameters of a permanent magnet synchronous motor.

[0025] Another embodiment of the present invention is to provide a permanent magnet synchronous motor parameter identification system, including a processing circuit and a memory electrically coupled thereto, wherein the memory is configured to store at least one program, wherein the program includes multiple instructions, and the processing circuit runs the program to execute the above-mentioned permanent magnet synchronous motor parameter identification method.

[0026] Compared with the prior art, the method, recording medium and system for identifying parameters of a permanent magnet synchronous motor provided by the present invention have the following beneficial effects:

[0027] (1) The method combining predictive control with high-frequency current injection is adopted, which eliminates the need to design an additional high-frequency injection module, reduces the complexity and computational complexity of the control system, and improves control efficiency.

[0028] (2) The problem of lack of rank in the parameter identification equation of the built-in permanent magnet synchronous motor is solved. The local convergence of the identification result is changed to the global convergence of the identification result, and the simultaneous acquisition of the identification results is achieved.

[0029] (3) Compared with the existing method, additional calculation and compensation are performed on the identification result errors caused by the dead zone effect and speed harmonics, which improves the accuracy of the identification results.

[0030] (4) The proposed real-time identification results can be directly applied to the control algorithm, which improves the robustness of the control system and ensures the operating stability of the built-in permanent magnet synchronous motor under various environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the process of the permanent magnet synchronous motor parameter identification method in an embodiment of the present invention;

[0032] Figure 2 It is a schematic diagram of a voltage instruction being modulated and output through a low-pass filter in an embodiment of the present invention;

[0033] Figure 3 Schematic diagram of the working principle of the notch filter in the embodiment of the present invention;

[0034] Figure 4 Schematic diagram of a permanent magnet synchronous motor control system in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making innovative efforts are within the scope of protection of the present invention.

[0036] like Figure 1-4 As shown, an embodiment of a permanent magnet synchronous motor parameter identification method provided by the present invention is as follows:

[0037] The first step is to inject high-frequency current signal

[0038] The control system of the built-in permanent magnet synchronous motor consists of a speed control loop and a current control loop. During the operation of the motor, the speed control loop provides the command current value for the current control loop. Then, based on the original current command, a high-frequency sinusoidal current command signal is added to it. The purpose is to add an additional excitation signal and increase the number of parameter identification equations to solve the problem of lack of rank in the identification equation. The process of adding a high-frequency current signal is as follows:

[0039]

[0040] in, and are the basic d-axis and q-axis current reference values, respectively, obtained by the speed control loop, is the command value of the injected d-axis high-frequency current, is the command value of the injected q-axis high-frequency current, α and ω hd are the amplitude and frequency of the injected d-axis high-frequency current, β and ω respectivelyhq are the amplitude and frequency of the injected q-axis high-frequency current respectively.

[0041] Among them, due to the discrete characteristics of the converter, current harmonics with frequencies 6 times and integer multiples of 6 of the operating frequency will be generated during the operation of the motor. Therefore, the injection current frequency avoids selecting frequencies 6 times and integer multiples of 6 of the motor operating frequency.

[0042] The real-time speed of the built-in permanent magnet synchronous motor is measured. In order to avoid the injection of sub-frequency harmonics in the measured speed, which affects the high-frequency current tracking effect, the present application designs a notch filter to eliminate the injection frequency high-frequency signal in the speed measurement signal. The transfer function of the speed notch filter is as follows:

[0043]

[0044] Where k1 and k2 are proportional constants of the notch filter, ω ef is the measured motor speed, ω e is the motor speed after filtering, and s represents the complex variable in Laplace transform.

[0045] The second step is high frequency signal extraction and parameter identification

[0046] After obtaining the real-time current of the built-in permanent magnet synchronous motor, the speed measurement result after filtering by the notch filter, and the command current after adding the high-frequency command signal, a simplified voltage discrete equation of the built-in permanent magnet synchronous motor in the dq rotating coordinate system is established, and the command voltage of the next cycle is obtained by the deadbeat predictive control method.

[0047]

[0048] Among them, L d0 is the given value of the d-axis inductance parameter in the predictive control, L q0 is the given value of the q-axis inductance parameter in predictive control, ψ f0 is the given value of permanent magnet flux parameter in predictive control, R0 is the given value of stator resistance parameter in predictive control, T s The control cycle is predicted. The parameter given value is given based on the rough estimation of the parameters of the built-in permanent magnet synchronous motor, and the command voltage vector is converted into a switch command after modulation to control the operation of the built-in permanent magnet synchronous motor.

[0049] The obtained command voltage is processed, multiplied by twice the cosine of the injected high-frequency signal phase, and then the inductance and stator resistance identification results are extracted through a low-pass filter. The direct-axis inductance identification result and the resistance identification result are:

[0050]

[0051] The quadrature-axis inductance identification result obtained by low-pass filter extraction is:

[0052]

[0053] The stator resistance identification result obtained by low-pass filter extraction is:

[0054]

[0055] Among them, LPF{} represents the result after filtering by a low-pass filter, the low-pass filter selects a second-order Butterworth low-pass filter, and the superscript Λ represents the identification result of the parameters.

[0056] Step 3: Parameter identification error compensation

[0057] In order to avoid the upper and lower poles from being turned on at the same time, the converter needs to set a dead time. The dead time effect will cause errors in the parameter identification results. In order to compensate for the errors caused by the dead time effect, a parameter identification dead time effect compensation method is proposed. First, the high-frequency voltage error caused by the dead time effect is calculated as follows:

[0058]

[0059] Where R ah , R ah and R ah The three-phase resistance error of A, B, and C is caused by the high-frequency voltage generated by the dead zone effect. The three-phase resistance error is ΔU is the phase voltage error, and k is the error constant.

[0060] The stator resistance identification error considering the dead zone effect error is:

[0061]

[0062] The stator resistance identification result is subtracted from the stator resistance identification error to obtain the final stator resistance identification value.

[0063] The permanent magnet flux identification results after considering the dead zone effect error are as follows:

[0064]

[0065] In the formula, is the DC value of the direct-axis command voltage, is the DC value of the quadrature-axis command voltage, is the direct-axis inductance identification result, is the identification result of the quadrature-axis inductance, i df is the actual DC current of the direct axis, i qf is the actual DC current of the quadrature axis, ω e is the rotor electrical angular velocity.

[0066] Step 4: Online verification of the accuracy of parameter identification results

[0067] After obtaining the parameter identification results taking into account the identification error, the parameter identification results are given to the command voltage acquisition equation in the predictive control, and then the accuracy of each parameter identification result is verified. The accuracy criterion of the permanent magnet flux identification result is:

[0068]

[0069] The accuracy criterion of the direct-axis inductance identification result obtained by the low-pass filter is:

[0070] J d =|LPF{K d i d cosω hd (tT s )}|

[0071] In the formula, K d It is the constant used as the criterion for the accuracy of direct-axis inductance identification results.

[0072] The accuracy criterion of the quadrature-axis inductance identification result obtained by the low-pass filter is:

[0073] J q =|LPF{K q i q cosω hq (tT s )}|

[0074] In the formula, K q It is the constant used as the criterion for the accuracy of direct-axis inductance identification results.

[0075] Step 5: High-frequency current injection control

[0076] When the accuracy criteria of the identification results of each parameter are within the specified range, stop the continuous injection of high-frequency current, use the currently identified parameters, intermittently inject high-frequency current to obtain the accuracy criteria of each parameter identification. If the accuracy criteria of the identification results of some or all parameters exceed the specified range, continue to inject high-frequency current again.

[0077] Compiling the above method steps into a program and then storing it on a hard disk or other non-transitory storage medium constitutes an embodiment of "a non-transitory readable recording medium" of the present invention; and electrically connecting the storage medium to a computer processor and completing the permanent magnet synchronous motor parameter identification through data processing constitutes an embodiment of "a permanent magnet synchronous motor parameter identification system" of the present invention.

[0078] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computers, available storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program codes.

[0079] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0080] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0081] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0082] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for identifying parameters of a permanent magnet synchronous motor, characterized in that: The following steps are involved: S1. Add a high-frequency current command to the current control loop, and superimpose the high-frequency sinusoidal current command values ​​on the d-axis and q-axis basic current reference values ​​obtained from the speed control loop to obtain the d-axis and q-axis current command values ​​after stimulation; S2. Run the deadbeat predictive control by using the motor parameters given before adding the high-frequency current, and establish a simplified voltage discrete equation of the built-in permanent magnet synchronous motor in the dq rotating coordinate system; collect relevant data and substitute them into the simplified voltage discrete equation, wherein the relevant data includes the real-time current and speed measurement results of the built-in permanent magnet synchronous motor and the command current after adding the high-frequency command signal, and obtain the current round command voltage; S3. Extract the cosine function of the high-frequency current command phase angle, multiply the double cosine function by the current round command voltage, and then filter it through a low-pass filter to obtain the modulated voltage value. Use the modulated voltage value to obtain the inductance, stator resistance and flux linkage to complete the current round of parameter identification, and feed the identified motor parameters back to the deadbeat predictive control algorithm for the next round of parameter identification; S4. Verify the accuracy of each parameter identification result based on the changes in the d-axis component and the q-axis component of the measured current. If the accuracy meets the standard, stop adding the high-frequency current command and complete the parameter identification.

2. A method for identifying parameters of a permanent magnet synchronous motor according to claim 1, characterized in that: The frequency of the added high-frequency current command should avoid selecting 6 times of the motor operating frequency or an integer multiple of 6.

3. A method for identifying parameters of a permanent magnet synchronous motor according to claim 2, characterized in that: The speed measurement result is corrected by a pre-designed notch filter transfer function, and the notch filter transfer function is as follows: Where k1 and k2 are proportional constants of the notch filter, ω ef is the measured motor speed, ω e is the motor speed after filtering, s represents the complex variable in Laplace transform, ω hd is the frequency of the injected d-axis high-frequency current, ω hq is the frequency of the injected q-axis high-frequency current.

4. A method for identifying parameters of a permanent magnet synchronous motor according to claim 3, characterized in that: Step S3 also includes correcting the parameter identification error caused by the dead zone effect of the converter. The specific steps are as follows: Calculate the high frequency voltage error caused by the dead zone effect: Where R ah , R ah and R ah The resistance error of three phases A, B and C caused by the high frequency voltage generated by the dead zone effect, i dh is the actual DC current of the direct axis, i qh is the actual DC current of the quadrature axis, θ r is the rotor position angle, and the three-phase resistance error is: ΔU is the phase voltage error, k is the error constant; The stator resistance identification error considering the dead zone effect error is: Where, LPF{} represents the result after filtering by a low-pass filter, and the low-pass filter selects a second-order Butterworth low-pass filter; Subtracting the stator resistance identification error from the stator resistance identification result to obtain a corrected stator resistance identification value; Calculate the permanent magnet flux correction value after considering the dead zone effect error: In the formula, is the DC value of the direct-axis command voltage, is the DC value of the quadrature-axis command voltage, is the direct-axis inductance identification result, is the identification result of the quadrature-axis inductance, i df is the actual DC current of the direct axis, i qf is the actual DC current of the quadrature axis, ω e is the rotor electrical angular velocity.

5. A non-transitory readable recording medium for storing one or more programs including a plurality of instructions, characterized in that: When the instruction is executed, the processing circuit will be caused to execute a permanent magnet synchronous motor parameter identification method according to any one of claims 1 to 4.

6. A permanent magnet synchronous motor parameter identification system, comprising a processing circuit and a memory electrically coupled thereto, characterized in that: The memory configuration stores at least one program, the program includes a plurality of instructions, and the processing circuit runs the program to execute a permanent magnet synchronous motor parameter identification method as described in any one of claims 1-4.

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