Method for identifying mechanical parameters of permanent magnet synchronous motor

Abstract

The invention belongs to the related technical field of motor parameter identification, and particularly relates to a permanent magnet synchronous motor mechanical parameter identification method, which comprises the steps of calculating an actual output electromagnetic torque value of a motor; on the basis of a given periodic speed instruction function, a speed instruction at the current motion moment t is calculated, and the periodic speed instruction function is composed of the sum of a trigonometric function and a direct current offset value with the same amplitude as the trigonometric function; the speed instruction at the current motion moment t is substituted into a theoretical electromagnetic torque equation of a permanent magnet synchronous motor control system, and theoretical electromagnetic torques of J, B and C to be identified are obtained; the value of the actual output electromagnetic torque and the theoretical electromagnetic torque about J, B and C are substituted into three integral functions respectively, the equation is solved to obtain the values of J, B and C, the starting time of an integral interval is arbitrary, and the three integral functions comprise a full-period integral function of the output electromagnetic torque constructed in advance based on a full-period torque integral method. According to the invention, the identification precision and efficiency can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field related to motor parameter identification, and more specifically, relates to a method for identifying mechanical parameters of a permanent magnet synchronous motor. Background Art

[0002] Due to its advantages such as simple structure, high power density, and smooth torque output, the permanent magnet synchronous motor has become the most commonly used motor in servo systems. In practical applications, due to changes in load and operating environment, the mechanical parameters of the permanent magnet synchronous motor will also change accordingly. In an actual permanent magnet synchronous motor servo control system, the mismatch of mechanical parameters such as moment of inertia, viscous friction coefficient, and Coulomb friction coefficient will all degrade the performance of the speed regulator of the servo control system, and further deteriorate the position tracking accuracy of the servo system. Therefore, there is an urgent need for an effective method for identifying the mechanical parameters of the permanent magnet synchronous motor.

[0003] There are currently various mechanical parameter identification methods for permanent magnet synchronous motors, but there are still problems such as complex implementation processes, fewer simultaneously identified parameters, and low identification accuracy. The article titled "Moment of Inertia and Friction Torque Coefficient Identification in a Servo Drive System" (S. Kim, IEEE Transactions on Industrial Electronics, 2019, 66(1): 60 - 70.) (Identification of the moment of inertia and friction torque coefficient in a servo drive system (S. Kim, Journal of Industrial Electronics, Vol. 55, No. 1, 2019, pp. 60 - 70)) identifies the moment of inertia and friction parameters of the system by applying a periodic speed command with a period of 2T composed of two alternating sine signals with different amplitudes and a period of T, combined with the half - period torque integration method. However, this method requires accurate determination of the speed zero - crossing point. In practical applications, due to the existence of the low - speed creep problem, it is often impossible to accurately determine the speed zero - crossing point. Additionally, this method also has the problem of under - determined rank of the equations. The motor needs to operate for two sine periods of 2T under two alternating sine signals with different amplitudes to obtain enough equations to solve for three mechanical parameters. Therefore, the identification result can only be updated every two sine periods, and the update of the identification result is slow. The article titled "Mechanical Parameter Identification Method for Permanent Magnet Servo System Based on Orthogonal Characteristics of Trigonometric Functions" (Wu Chun et al., Proceedings of the CSEE, 2022, 42(4): 1617 - 1625) identifies the moment of inertia and friction parameters of the system by applying a periodic speed command with a period of 2T composed of two alternating sine signals with different amplitudes and a period of T, combined with the orthogonal characteristics of trigonometric functions and the full - period torque integration method. This method does not require the determination of the speed zero - crossing point, but there is still the problem of slow update of the identification result due to under - determined rank of the equations. In addition, both of the above - mentioned methods are based on the assumption that the actual speed accurately tracks the given speed. However, the speed commands given in the above - mentioned two methods have speed zero - crossing points, and the existence of friction commutation will cause the speed tracking error to suddenly increase at the speed zero - crossing point of the system, thereby reducing the identification accuracy.

[0004] Therefore, it is necessary to design a more effective mechanical parameter identification method for permanent magnet synchronous motors to overcome the problems that the above - mentioned methods are difficult to implement due to the need to accurately determine the speed zero - crossing point, the slow update of the identification result due to under - determined rank of the equations, and the reduction of the identification accuracy due to friction commutation. Summary of the Invention

[0005] In view of the above deficiencies or improvement requirements of the prior art, the present invention provides a method for identifying mechanical parameters of a permanent magnet synchronous motor, aiming to improve the efficiency and accuracy of mechanical parameter identification by overcoming the problems of slow update of the identification result caused by the underdetermined rank of the equation and reduced identification accuracy caused by friction commutation.

[0006] To achieve the above object, according to one aspect of the present invention, a method for identifying mechanical parameters of a permanent magnet synchronous motor is provided. The mechanical parameters to be identified simultaneously are the moment of inertia J, the viscous friction coefficient B, and the Coulomb friction coefficient C. The method includes:

[0007] Collect the direct-axis current and quadrature-axis current of the motor through a current sensor to calculate the actual output electromagnetic torque value of the motor;

[0008] Based on a given periodic speed command function, calculate the speed command at the current motion time t, where the periodic speed command function is a periodic angular velocity command composed of the sum of a trigonometric function and a DC offset value with the same amplitude as it; substitute the speed command at the current motion time t into the theoretical electromagnetic torque equation of the permanent magnet synchronous motor control system to obtain the theoretical electromagnetic torque of the permanent magnet synchronous motor control system regarding J, B, and C to be identified under the condition that the actual angular velocity completely follows the periodic angular velocity command.

[0009] Substitute the actual output electromagnetic torque value and the theoretical electromagnetic torque regarding J, B, and C to be identified into three integral functions respectively, and make the values of the same integral function corresponding to the actual output electromagnetic torque value and the theoretical electromagnetic torque equal, so as to obtain the values of J, B, and C by solving the system of equations. When solving the system of equations, the starting moment of the integral interval is an arbitrary moment. The three integral functions are: the full-period integral function of the output electromagnetic torque constructed in advance based on the full-period torque integration method and the full-period integral functions of the product of the output electromagnetic torque and two trigonometric functions respectively.

[0010] Furthermore, the theoretical electromagnetic torque equation of the permanent magnet synchronous motor control system is a mechanical motion equation of the permanent magnet synchronous motor considering friction effects established based on the Coulomb-viscous friction model of the permanent magnet synchronous motor.

[0011] Furthermore, the periodic speed command function is:

[0012]

[0013] where A is the amplitude of the trigonometric function and also the added DC offset value, ω h is the given angular velocity frequency, is the initial phase, and t is the motion time.

[0014] Furthermore, the three integral functions are:

[0015]

[0016] In the formula, t0 is the starting integration time, Sum1 is the output electromagnetic torque T e The full-cycle integral value of the product with the sine function, Sum2 is the full-cycle integral value of the product of the output electromagnetic torque and the cosine function, Sum3 is the full-cycle integral function of the output electromagnetic torque, ω h Is the given angular velocity frequency, Is the initial phase.

[0017] According to another aspect of the present invention, there is provided an electronic device, including a memory and a processor, the memory stores a computer program, and when the processor executes the computer program, the steps of the method described above are implemented.

[0018] According to another aspect of the present invention, there is provided a computer-readable storage medium, the computer-readable storage medium includes a stored computer program, wherein when the computer program is run by a processor, the device where the storage medium is located is controlled to execute the steps of the method described above.

[0019] According to another aspect of the present invention, there is provided a computer program product, including a computer program or instruction, and when the computer program or instruction is executed by a processor, the steps of the method described above are implemented.

[0020] Generally speaking, compared with the prior art by the above technical solution conceived by the present invention, the technical solution provided by the present invention mainly has the following beneficial effects:

[0021] The present invention proposes a method for identifying mechanical parameters of a permanent magnet synchronous motor. First, a speed command signal with a DC bias is proposed. Under this speed command signal, there is no zero-crossing point of the motor speed, eliminating the influence of friction commutation on the identification accuracy from the source and avoiding the problem that the speed tracking error increases at the zero-crossing point of the speed due to friction commutation, which leads to a decrease in the identification accuracy. Secondly, on the basis of the proposed speed command signal with a DC bias, a third equation for directly integrating the actual electromagnetic torque over a full cycle is introduced. By increasing the number of calculation equations, the problem of underdetermined rank of the equations is solved, and the identification of three mechanical parameters is realized within a sine speed cycle, and the identification result is relatively faster than the existing methods. In addition, the present invention uses the full-cycle torque integration method, and the starting moment of the integration interval can be any moment, so there is no need to judge the zero-crossing point of the speed, which is easier to implement in practice and avoids the problem that the existing methods need to accurately judge the zero-crossing point of the speed. Under the mechanical parameter identification method proposed in the present invention, the parameter identification accuracy is significantly improved, the update time of the identification result is shortened by 50%, and there is no need to judge the zero-crossing point of the speed, so the implementation is simple, realizing the accurate, fast and simple identification of multiple mechanical parameters of the permanent magnet synchronous motor. Therefore, the present invention can improve the accuracy and efficiency of mechanical parameter identification by overcoming the problems of slow update of the identification result caused by underdetermined rank of the equations and reduced identification accuracy caused by friction commutation. Description of the Drawings

[0022] Figure 1 It is a flow block diagram of a method for identifying mechanical parameters of a permanent magnet synchronous motor provided by an embodiment of the present invention;

[0023] Figure 2 It is a schematic diagram of mechanical parameter identification provided by an embodiment of the present invention;

[0024] Figure 3 It is an experimental waveform diagram of the given angular velocity command and the feedback angular velocity provided by an embodiment of the present invention;

[0025] Figure 4 It is an experimental result diagram of the identification of the moment of inertia, viscous friction coefficient, and Coulomb friction coefficient provided by an embodiment of the present invention;

[0026] Figure 5 It is an experimental waveform diagram of the given angular velocity command and the feedback speed for comparative verification using the method proposed by S. Kim in the comparative verification provided by an embodiment of the present invention;

[0027] Figure 6 It is an experimental result diagram of the identification of the moment of inertia, viscous friction coefficient, and Coulomb friction coefficient for comparative verification using the method proposed by S. Kim in the comparative verification provided by an embodiment of the present invention;

[0028] Figure 7The experimental waveform diagram of the given angular velocity command and the feedback angular velocity for the comparative verification provided in the embodiments of the present invention using the method proposed by Wu Chun for comparative verification;

[0029] Figure 8 The identification experimental result diagram of the moment of inertia, viscous friction coefficient, and Coulomb friction coefficient for the comparative verification provided in the embodiments of the present invention using the method proposed by Wu Chun for comparative verification. Specific implementation manners

[0030] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] Embodiment 1

[0032] A method for identifying mechanical parameters of a permanent magnet synchronous motor, as Figure 1 shown, the mechanical parameters identified simultaneously are the moment of inertia J, the viscous friction coefficient B, and the Coulomb friction coefficient C. The method includes:

[0033] Collect the direct-axis current and quadrature-axis current of the motor through a current sensor to calculate the actual output electromagnetic torque value of the motor;

[0034] Based on a given periodic velocity command function, calculate the velocity command at the current motion moment t, where the periodic velocity command function is a periodic angular velocity command composed of the sum of a trigonometric function and a DC offset value with the same amplitude as it; substitute the velocity command at the current motion moment t into the theoretical electromagnetic torque equation of the permanent magnet synchronous motor control system to obtain the theoretical electromagnetic torque of the permanent magnet synchronous motor control system regarding the J, B, and C to be identified under the condition that the actual angular velocity completely follows the periodic angular velocity command;

[0035] Substitute the actual output electromagnetic torque value and the theoretical electromagnetic torque regarding the J, B, and C into three integral functions respectively, and make the values of the same integral function corresponding to the actual output electromagnetic torque value and the theoretical electromagnetic torque equal, and solve the equations to obtain the values of J, B, and C. When solving the equations, the starting moment of the integral interval is randomly preset. The three integral functions are: the full-period integral function of the output electromagnetic torque constructed in advance based on the full-period torque integration method and the full-period integral functions of the product of the output electromagnetic torque and two trigonometric functions respectively.

[0036] Aiming at the problem that the existing method has an increased rotational speed tracking error at the zero-crossing point of speed due to friction commutation, which further leads to a decrease in identification accuracy, the present invention proposes a rotational speed command signal with a DC bias. Under this rotational speed command signal, there is no zero-crossing point of rotational speed in the motor, eliminating the influence of friction commutation on identification accuracy from the source. Aiming at the problem that the existing method has a slow update of the identification result caused by the underdetermined rank of the equation, based on the proposed rotational speed command signal with a DC bias, the present invention introduces a third equation that directly integrates the actual electromagnetic torque over a full cycle, solving the problem of underdetermined rank of the equation by increasing the number of calculation equations, and realizing the identification of three mechanical parameters within a sine rotational speed cycle. Aiming at the problem that the existing method needs to accurately judge the zero-crossing point of speed, this embodiment uses the full-cycle torque integration method, and the starting moment of the integration interval can be any moment, so there is no need to judge the zero-crossing point of speed, which is easier to implement in practice. Under the mechanical parameter identification method proposed in the present invention, the parameter identification accuracy is significantly improved, the update time of the identification result is shortened by 50%, there is no need to judge the zero-crossing point of speed, so the implementation is simple, and the multi-parameter accurate, fast and simple identification of the mechanical parameters of the permanent magnet synchronous motor is realized. Therefore, the method of this embodiment can simultaneously overcome the problems of the existing identification method, that is, it is difficult to implement due to the need to accurately judge the zero-crossing point of speed, the slow update of the identification result due to the underdetermined rank of the equation, and the decrease in identification accuracy due to friction commutation.

[0037] Preferably, the theoretical electromagnetic torque equation of the permanent magnet synchronous motor control system is a mechanical motion equation of the permanent magnet synchronous motor considering friction effects, which is established based on the Coulomb-viscous friction model of the permanent magnet synchronous motor.

[0038] In specific implementation, first, a Coulomb-viscous friction model of the permanent magnet synchronous motor is constructed, and a mechanical motion equation of the permanent magnet synchronous motor considering friction effects is established.

[0039] The Coulomb-viscous friction model is as follows:

[0040] T f =Bω + Csgn(ω)

[0041] In the formula, T f is the total friction torque, ω is the mechanical angular velocity, B is the viscous friction coefficient, C is the Coulomb friction coefficient, and sgn() is the sign function.

[0042] The established mechanical motion equation of the permanent magnet synchronous motor considering friction effects is:

[0043] T f =T fB +T fC =Bω + Csgn(ω)

[0044] In the formula, T f is the total friction torque, TfB is the viscous friction torque, T fC is the Coulomb friction torque, ω is the mechanical angular velocity, B is the viscous friction coefficient, C is the Coulomb friction coefficient, and sgn() is the sign function.

[0045] In the method of this embodiment, the periodic angular velocity command formed by adding a given trigonometric function and a DC bias value equal to the amplitude of the trigonometric function is expressed as:

[0046]

[0047] where A is the amplitude of the trigonometric function and also the added DC bias value, ω h is the given angular velocity frequency, is the initial phase, and t is the motion time.

[0048] When taking different values, the content in the brackets in the periodic angular velocity command formula can be in the form of 1 - cos, 1 + cos, 1 - sin, or 1 + sin.

[0049] Then, under the assumption that the actual angular velocity completely follows the periodic angular velocity command, the theoretical electromagnetic torque of the permanent magnet synchronous motor control system at this time is:

[0050]

[0051] The direct-axis current and quadrature-axis current of the motor are collected through a current sensor to calculate the actual output electromagnetic torque T of the motor e is:

[0052]

[0053] where P n is the number of pole pairs of the motor, L d is the direct-axis inductance, L q is the quadrature-axis inductance, ψ f is the permanent magnet flux linkage, i d is the direct-axis current, i q is the quadrature-axis current.

[0054] In each motion cycle, the full-cycle integral value of the actual output electromagnetic torque and the full-cycle integral value of the product of the actual output electromagnetic torque and the trigonometric function are:

[0055]

[0056] where t0 is the starting integration time, and Sum1 is the output electromagnetic torque T eThe full - period integral value of the product with the sine function, Sum2 is the full - period integral value of the product of the output electromagnetic torque and the cosine function, Sum3 is the full - period integral function of the output electromagnetic torque, ω h is the given angular velocity frequency, is the initial phase.

[0057] In each motion period, the full - period integral value of the theoretical electromagnetic torque and the full - period integral value of the product of the theoretical electromagnetic torque and the trigonometric function are:

[0058]

[0059]

[0060] In the formula, t0 is the starting integration time.

[0061] It is approximately considered that the actual output electromagnetic torque is equal to the theoretical electromagnetic torque:

[0062]

[0063] After each motion period, calculate and update the mechanical parameters of the permanent - magnet synchronous motor as:

[0064]

[0065] In the formula, is the identification result of the moment of inertia, is the identification result of the viscous friction coefficient, is the identification result of the Coulomb friction coefficient.

[0066] The principle of a method for identifying the mechanical parameters of a permanent - magnet synchronous motor proposed in this embodiment is as Figure 2 shown. At a periodic given angular velocity, the output electromagnetic torque of the permanent - magnet synchronous motor includes an inertial torque, a viscous friction torque, and a Coulomb friction torque. And the inertial torque is π / 2 ahead of the given angular velocity in phase, the viscous friction torque is in the same phase as the given angular velocity, and the Coulomb friction torque only depends on the positive or negative of the given angular velocity. In practical applications, due to the inevitable phase lag in the digital control system, the actual angular velocity of the system is always positive or always negative at the given angular velocity. Therefore, there is no zero - crossing of the speed, and the Coulomb friction torque remains constant all the time. Thus, the speed tracking error of the system is small.

[0067] By using the orthogonality of trigonometric functions and integrating the output electromagnetic torque over a full period, the inertial torque, the viscous friction torque, and the Coulomb friction torque can be separated, realizing the synchronous parameter identification of the moment of inertia, the viscous friction coefficient, and the Coulomb friction coefficient of the permanent - magnet synchronous motor.

[0068] Therefore, generally speaking, a mechanical parameter identification method for a permanent magnet synchronous motor provided by this embodiment is based on a given periodic speed command function, and combines the full-cycle torque integration method. By using the orthogonal characteristics of trigonometric functions and the phase relationship of different torques, the inertia torque, viscous friction torque, and Coulomb friction torque in the output electromagnetic torque are separated, and multiple mechanical parameters of the permanent magnet synchronous motor can be identified and updated simultaneously. Moreover, it can achieve fast and accurate identification of the mechanical parameters of the permanent magnet synchronous motor. At the same time, the identification effect does not depend on the initial estimated value of the given mechanical parameters, greatly improving the performance of the permanent magnet synchronous motor servo control system.

[0069] To verify the effectiveness and superiority of the parameter identification method proposed by the present invention, the following experiments are carried out:

[0070] The permanent magnet synchronous motor control system used in the experiment adopts control mode, the rated power of the motor P N = 750W, the number of pole pairs P n = 5, the direct-axis inductance L d = 2.6mH, the quadrature-axis inductance L q = 2.6mH, the permanent magnet flux linkage ψ f = 4.437×10 -2 Wb, the total moment of inertia J = 1.52×10 -4 kg·m 2 , the viscous friction coefficient B = 2.8×10 -3 N·m / (rad / s), the Coulomb friction coefficient C = 0.125N·m.

[0071] The given angular velocity ω * = 50[1 + cos(4πt + π)]rad / s, the waveforms of the system given angular velocity and the actual angular velocity are as Figure 3 shown. It can be seen that since there is no zero-crossing point of the velocity, the actual angular velocity can well track the given angular velocity. The assumption that the output electromagnetic torque proposed by the present invention is equal to the theoretical electromagnetic torque approximately holds, the identification accuracy is significantly improved, and the update time of the identification result is shortened by 50%. The identification results of the mechanical parameters of the permanent magnet synchronous motor under the method proposed by the present invention are as Figure 4 . Only one rotation period (0.5s) is required to obtain the identification results of the mechanical parameters of the permanent magnet synchronous motor and quickly converge to near the true value. The final identification result of the moment of inertia is the identification error is +2.6%; the final identification result of the viscous friction coefficient is the identification error is -22.5%; the final identification result of the Coulomb friction coefficient is the identification error is +3.2%. It can be seen from the experimental results that the present invention can achieve accurate, fast, and simple multi-parameter identification of the mechanical parameters of the permanent magnet synchronous motor through a simple identification process.

[0072] To illustrate the advantages of the present invention over the existing methods, comparative verification is given as follows:

[0073] For comparative verification using the existing method, the permanent magnet synchronous motor control system used in the experiment adopts control mode, the rated power of the motor is P N = 750 W, the number of pole pairs is P n = 5, the direct-axis inductance is L d = 2.6 mH, the quadrature-axis inductance is L q = 2.6 mH, the permanent magnet flux linkage is ψ f = 4.437×10 -2 Wb, the total moment of inertia is J = 1.52×10 -4 kg·m 2 , the viscous friction coefficient is B = 2.8×10 -3 N·m / (rad / s), and the Coulomb friction coefficient is C = 0.125 N·m.

[0074] Under the condition of keeping the maximum given speed equal, the permanent magnet synchronous motor parameter identification experiment is carried out using the method proposed by S. Kim. The given angular velocity and the feedback angular velocity are as Figure 5 shown, and the identification results of the mechanical parameters are as Figure 6 shown. The experimental results show that when a periodic speed command with a period of 2T composed of alternating 50sin(4πt) rad / s and 100sin(4πt) rad / s of the given sine signal is given, a parameter identification result can be obtained after two sine periods 2T (1 s). The final identification result of the moment of inertia is the identification error is -8.3%; the final identification result of the viscous friction coefficient is the identification error is -25.7%; the final identification result of the Coulomb friction coefficient is the identification error is +12.0%.

[0075] Under the condition of keeping the maximum given speed equal, the permanent magnet synchronous motor parameter identification experiment is carried out using the method proposed by Wu Chun. The given angular velocity and the feedback angular velocity are as Figure 7 shown, and the identification results of the mechanical parameters are as Figure 8 shown. The experimental results show that when a periodic speed command with a period of 2T composed of alternating 50sin(4πt) rad / s and 100sin(4πt) rad / s of the given sine signal is given, a parameter identification result can be obtained after two sine periods 2T (1 s). The final identification result of the moment of inertia is the identification error is -5.3%; the final identification result of the viscous friction coefficient is the identification error is -25.0%; the final identification result of the Coulomb friction coefficient is The identification error is +9.6%.

[0076] Embodiment 2

[0077] This application also relates to an electronic device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the steps of the above method are implemented.

[0078] The electronic device can be a computing device such as a desktop computer, a notebook, a palm computer, and a cloud server. The so-called processor may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The memory can be used to store computer programs and / or modules. By running or executing the computer programs and / or modules stored in the memory, and calling the data stored in the memory, various functions of the electronic device can be realized.

[0079] The related technical solutions are the same as above and will not be elaborated here.

[0080] Embodiment 3

[0081] This application also relates to a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above method are implemented.

[0082] Specifically, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, at least one magnetic disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0083] The related technical solutions are the same as above and will not be elaborated here.

[0084] Embodiment 4

[0085] An embodiment of the present application provides a computer program product or a computer program. The computer program product or the computer program includes computer instructions, and the computer instructions are stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the steps of the method in the above embodiments of the present application.

[0086] The related technical solutions are the same as above and will not be elaborated here.

[0087] It is easy for those skilled in the art to understand that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for identifying mechanical parameters of a permanent magnet synchronous motor, characterized in that, The mechanical parameters identified simultaneously are the moment of inertia J, the viscous friction coefficient B, and the Coulomb friction coefficient C. The method includes: Collecting the direct-axis current and the quadrature-axis current of the motor through a current sensor to calculate the actual output electromagnetic torque value of the motor; Based on a given periodic speed command function, calculating the speed command at the current motion moment t, where the periodic speed command function is a periodic angular velocity command composed of the sum of a trigonometric function and a DC bias value with the same amplitude as it; substituting the speed command at the current motion moment t into the theoretical electromagnetic torque equation of the permanent magnet synchronous motor control system to obtain the theoretical electromagnetic torque of the permanent magnet synchronous motor control system regarding J, B, and C to be identified under the condition that the actual angular velocity completely follows the periodic angular velocity command; Substituting the actual output electromagnetic torque value and the theoretical electromagnetic torque regarding J, B, and C into three integral functions respectively, and making the values of the same integral function corresponding to the actual output electromagnetic torque value and the theoretical electromagnetic torque equal, and obtaining the values of J, B, and C by solving the system of equations. When solving the system of equations, the starting moment of the integral interval is any moment. The three integral functions are: the full-period integral function of the output electromagnetic torque constructed in advance based on the full-period torque integration method and the full-period integral functions of the product of the output electromagnetic torque and two trigonometric functions respectively.

2. The mechanical parameter identification method of a permanent magnet synchronous motor according to claim 1, characterized in that, The theoretical electromagnetic torque equation of the permanent magnet synchronous motor control system is a mechanical motion equation of the permanent magnet synchronous motor considering friction effects established based on the Coulomb-viscous friction model of the permanent magnet synchronous motor.

3. A method for identifying mechanical parameters of a permanent magnet synchronous motor according to claim 1, characterized in that, The periodic speed command function is: where A is the amplitude of the trigonometric function and also the DC bias value added, ω h is the given angular velocity frequency, is the initial phase, and t is the motion time.

4. The mechanical parameter identification method of a permanent magnet synchronous motor according to claim 2, characterized in that The three integral functions are: where t0 is the starting integration time, Sum1 is the full-cycle integral value of the product of the output electromagnetic torque T e and the sine function, Sum2 is the full-cycle integral value of the product of the output electromagnetic torque and the cosine function, Sum3 is the full-cycle integral function of the output electromagnetic torque, ω h is the given angular velocity frequency, is the initial phase.

5. An electronic device, comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 4.

6. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored computer program, wherein when the computer program is run by a processor, it controls the device where the storage medium is located to execute the steps of the method according to any one of claims 1 to 4.

7. A computer program product comprising a computer program or instructions, characterized in that, When the computer program or instruction is executed by a processor, it implements the steps of the method according to any one of claims 1 to 4.

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