Permanent magnet synchronous motor health state monitoring method and system based on magnetic steel temperature

Abstract

The invention relates to a permanent magnet synchronous motor health state monitoring method and system based on magnetic steel temperature, and the method comprises the steps: finding out a stable working condition through analyzing a whole vehicle road spectrum; testing flux linkage values and convergence error basic values under different temperatures and different steady-state working conditions are obtained and stored by changing the rotor temperature and the steady-state working conditions; if the current rotor is in the steady-state working condition, obtaining a current rotor temperature and a flux linkage difference value, and calculating a current real flux linkage value; and calculating a loss-of-excitation proportion, dividing into corresponding health levels according to the loss-of-excitation proportion, and transmitting and storing the health levels. According to the method, the road spectrum of the whole vehicle is analyzed, the steady-state working condition is found out, data collected under the steady-state working condition is accurate, misjudgment is avoided, meanwhile, the influence of the temperature on the motor is considered, the real flux linkage value and the excitation loss proportion are accurately calculated and divided into different health levels, and the health state in the vehicle driving process can be known by the background; the failure condition of the whole vehicle power system part can be pre-judged in advance, and the safety of passengers and the vehicle is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of motor monitoring, and in particular to a method and system for monitoring the health status of a permanent magnet synchronous motor based on magnetic steel temperature. Background Art

[0002] With the popularity of new energy vehicles, their reliability and durability have attracted more and more attention. Permanent magnet synchronous motors have become the first choice for the main drive motors of new energy vehicles due to their high efficiency, high power density and wide speed regulation range. The working conditions of automotive motors are complex and the environment is changeable. The high temperature and high humidity environment, large weak magnetic current application, impact and vibration environment can easily lead to permanent and irreversible demagnetization of the permanent magnet motor rotor magnets, thus affecting the safety and power of the vehicle and causing an unpleasant driving experience.

[0003] The invention patent with the publication number CN116743020A discloses a method and device for detecting demagnetization of a permanent magnet synchronous motor based on operating electrical parameters. The device includes: calculating the flux of the permanent magnet according to the operating parameters of the permanent magnet synchronous motor and the control system; judging whether the permanent magnet synchronous motor is demagnetized by the calculated flux information. Through this method and device, the motor body parameters calibrated by the necessary bench are used to calculate the value of the flux using the voltage equation of the motor in the normal working state; the patent calculates the flux based on the operating parameters to detect the demagnetization of the permanent magnet synchronous motor, but the patent lacks a comparison under normal conditions, ignores the influence of temperature on the flux, and only makes judgments through calculations, lacks judgments on different states of the permanent magnet synchronous motor, and makes corresponding treatments according to different states.

[0004] Therefore, providing a permanent magnet synchronous motor health status monitoring method based on magnetic steel temperature is an issue that is urgently needed to be addressed. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a permanent magnet synchronous motor health status monitoring method and system based on magnetic steel temperature.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] According to one aspect of the present invention, a method for monitoring the health status of a permanent magnet synchronous motor based on magnetic steel temperature is provided, the method comprising the following steps:

[0008] S1. Analyze the vehicle road spectrum to find the stable operating condition with rated input voltage, fixed motor speed and fixed motor torque;

[0009] S2, powertrain EOL offline test, by changing the rotor temperature and steady-state conditions, the test flux value and convergence error base value under different temperatures and different steady-state conditions are obtained and stored;

[0010] S3. During normal driving, the current steady-state operating condition is determined. If the rotor is in a steady-state operating condition, the current rotor temperature and flux difference are obtained, and the current true flux value is calculated by combining the test flux value under the corresponding temperature and steady-state operating condition and the convergence error base value;

[0011] S4. Calculate the demagnetization ratio according to the real magnetic flux value, divide it into corresponding health levels according to the demagnetization ratio, and transmit and store the health levels.

[0012] As a preferred technical solution, the calculation of the real magnetic flux value is specifically as follows:

[0013]

[0014] Ψ m1 and m2 They are the test flux values ​​with different temperatures and the same steady-state conditions, Flux_BaseErr1 and Flux_BaseErr2 are the convergence error base values ​​with different temperatures and the same steady-state conditions, Del_Flux is the flux difference, Ψ m is the actual magnetic flux value.

[0015] As a preferred technical solution, the method adopts a PID current error closed loop to obtain a flux difference.

[0016] As a preferred technical solution, the calculation and derivation of the magnetic flux difference is specifically as follows:

[0017]

[0018]

[0019] is the change of the cross-axis flux, W e is the motor electrical frequency, I d is the direct axis current, I q is the quadrature axis current, is the rotor flux, R s is the stator resistance, L d is the direct-axis inductance, I q (k) is the quadrature axis current sampled at the current moment, I q (k-1) is the quadrature axis current obtained at the last sampling moment, L q is the quadrature-axis inductance, T s To control the switching frequency, U q is the quadrature axis voltage.

[0020] As a preferred technical solution, the rotor temperature includes 20degC, 80degC and 120degC.

[0021] As a preferred technical solution, the demagnetization ratio is calculated as follows:

[0022]

[0023] Ψ m1 is the test flux value at the same temperature and steady-state condition, Ψ m is the real flux linkage value under the same temperature and steady-state conditions, and Y is the demagnetization ratio.

[0024] As a preferred technical solution, the health level is divided into three levels: I, II and III according to the demagnetization ratio.

[0025] As a preferred technical solution, the demagnetization ratio range is 0-5% as I, the demagnetization ratio range is 5%-10% as II, and the demagnetization ratio range is greater than 10% as III.

[0026] According to another aspect of the present invention, there is provided a system adopting any of the above methods for monitoring the health status of a permanent magnet synchronous motor based on magnetic steel temperature, the system comprising a magnetic flux health grading management module, an analysis module, a data acquisition module, a calculation module and a test module, the analysis module being used to analyze the road spectrum of the entire vehicle and find out the steady-state operating condition, the data acquisition module collecting current data in real time, the test module collecting test data, the magnetic flux health grading management module storing the health level in NVM or feeding it back to the bus, the calculation module calculating the demagnetization ratio; the calculation module completes the calculation according to the data of the analysis module, the data acquisition module and the test module, and transmits the calculation result to the magnetic flux health grading management module.

[0027] As a preferred technical solution, the system further includes a flux observer, and the flux observer is a current-based flux observer.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention analyzes the road spectrum of the whole vehicle to find the steady-state working condition. The data collected under the steady-state working condition is more accurate, avoiding misjudgment. At the same time, the influence of temperature on the motor is considered, and the real magnetic flux value and demagnetization ratio are calculated more accurately, which are divided into different health levels. The background can know the health status of the vehicle during driving, and can predict the failure of part of the vehicle power system in advance to ensure the safety of passengers and vehicles.

[0030] 2. The present invention calibrates each motor parameter and model closed-loop convergence by performing EOL offline testing, thereby reducing the impact of individual differences in motors and controllers on the estimation results, and at the same time also effectively eliminates the impact of system nonlinearity on the results.

[0031] 3. The present invention is an online real-time calculation with simple calculation logic, which does not require a large amount of software computing resources and has little impact on the load rate of the main control core.

[0032] 4. The present invention does not require additional hardware resources, does not require additional vehicle maintenance (4S shop) hardware equipment investment, and can obtain health information quickly and conveniently. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the process of the present invention;

[0034] Figure 2 It is a schematic diagram of the control flow of the flux observer of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0036] There are three mainstream methods for monitoring the health status of magnetic steel. Solution 1: When a new energy vehicle returns to the after-sales maintenance store, the engine is used to pull up the motor to indirectly monitor the phase voltage or ASC current to obtain the back electromotive force information to determine whether the magnetic steel performance is attenuated. This method is simple and direct, but it requires the motor to be passively turned to a fixed speed, which is not suitable for pure electric vehicle scenarios, and it is impossible to monitor the health status during driving; Solution 2: Special sensors are installed at the rotor position to monitor the attenuation of the permanent magnet flux value. This method requires increased hardware costs, and the sensor has aging and failure problems, so it is not suitable for automotive industry application scenarios that pursue low cost and high performance; Solution 3: Use high-level control algorithms or artificial intelligence algorithms to monitor the health of magnetic steel. This solution has superior performance and does not require the addition of additional hardware equipment, but it requires real-time software computing resources, increases the control core load rate, and is difficult to apply in actual mass production projects.

[0037] Therefore, the present invention provides a permanent magnet synchronous motor health status monitoring method and system based on magnetic steel temperature. The present invention analyzes the road spectrum of the whole vehicle to find the steady-state working condition. The data collected under the steady-state working condition is relatively accurate, avoiding misjudgment. At the same time, the influence of temperature on the motor is considered, and the real magnetic flux value and demagnetization ratio are calculated more accurately, which are divided into different health levels. The background can know the health status of the vehicle during driving, and can predict the partial failure of the whole vehicle power system in advance to ensure the safety of passengers and vehicles. The present invention calibrates each motor parameter and model closed-loop convergence by performing EOL offline testing, reduces the influence of individual differences of motors and controllers on the estimation results, and at the same time, it also eliminates the influence of system nonlinearity on the results. The present invention is online real-time calculation, the calculation logic is simple, does not need to occupy more software computing resources, and has little effect on the main control core load rate. The present invention does not need to increase additional hardware resources, does not need to increase the hardware equipment investment of vehicle maintenance (4S shop), and can obtain health information conveniently and quickly.

[0038] Example 1

[0039] like Figure 1 As shown, a permanent magnet synchronous motor health status monitoring method based on magnetic steel temperature comprises the following steps:

[0040] S1. Analyze the vehicle road spectrum to find the stable operating condition with rated input voltage, fixed motor speed and fixed motor torque;

[0041] S2, powertrain EOL offline test, by changing the rotor temperature and steady-state conditions, the test flux value and convergence error base value under different temperatures and different steady-state conditions are obtained and stored;

[0042] S3. During normal driving, the current steady-state operating condition is determined. If the rotor is in a steady-state operating condition, the current rotor temperature and flux difference are obtained, and the current true flux value is calculated by combining the test flux value under the corresponding temperature and steady-state operating condition and the convergence error base value;

[0043] S4. Calculate the demagnetization ratio according to the real magnetic flux value, divide it into corresponding health levels according to the demagnetization ratio, and transmit and store the health levels.

[0044] In this embodiment, the first step is to analyze the vehicle operating conditions, extract relatively stable operating conditions in common driving processes from the vehicle road spectrum, and obtain the input voltage Udc, motor speed Spd and motor request torque Tcmd; the second step is to use the heating method on the EOL test bench to operate at the steady-state conditions of rated bus voltage, fixed motor speed and fixed motor torque at different rotor temperatures (20degC, 80degC, 120degC), and the flux linkage value Ψ corresponding to the rated bus voltage, fixed motor speed and fixed motor torque in the first step ism , and record the corresponding observer convergence error base value Flux_BaseErr under this working condition; if there are multiple groups of working conditions, such as different rated bus voltage, fixed motor speed and fixed motor torque of each group, it is necessary to record the corresponding convergence error values ​​under multiple groups of working conditions; the third step is to determine whether the vehicle is in the steady-state working condition range defined in the first step, and start the flux observation and health detection in the range. The flux observer based on the current calculates in real time to obtain the flux difference Del Flu x And health grade information, the fourth step is to transmit the health grade information to the bus through the vehicle CAN, and store it in NVM (non-volatile memory) at the same time, and read it when the vehicle is maintained.

[0045] The calculation of the real magnetic flux value is specifically as follows:

[0046]

[0047] Ψ m1 and m2 They are the test flux values ​​with different temperatures and the same steady-state conditions, Flux_BaseErr1 and Flux_BaseErr2 are the convergence error base values ​​with different temperatures and the same steady-state conditions, Del_Flux is the flux difference, Ψ m is the real flux value. The rotor temperatures include 20degC, 80degC and 120degC.

[0048] In this embodiment, for example, the convergence error obtained by the EOL test at 20degC is Flux_BaseErr1, and the corresponding test flux value Ψ m1 , the convergence error obtained by the EOL test at 80degC is Flux_BaseErr2, and the corresponding test flux value Ψ m2 When the vehicle enters the steady-state condition during operation, the flux difference is Del_Flux when the rotor temperature is 20degC, so the real flux value Ψ m It can be obtained by the above formula.

[0049] like Figure 2 As shown, the method adopts a PID current error closed loop to obtain a flux difference.

[0050] The calculation derivation of the flux difference is specifically as follows:

[0051]

[0052]

[0053] is the change of the cross-axis flux, W e is the motor electrical frequency, Id is the direct axis current, I q is the quadrature axis current, is the rotor flux, R s is the stator resistance, L d is the direct-axis inductance, I q (k) is the quadrature axis current sampled at the current moment, I q (k-1) is the quadrature axis current obtained at the last sampling moment, L q is the quadrature-axis inductance, T s To control the switching frequency, U q is the quadrature axis voltage.

[0054] In this embodiment, based on the quadrature-axis voltage equation and transient flux equation of the permanent magnet synchronous motor, the quadrature-axis current I q (k), and the quadrature axis current T obtained at the previous sampling moment q (k-1) is used to compare and calculate the flux difference, and the steady-state voltage equation is corrected in real time to achieve closed-loop control.

[0055] The calculation of the demagnetization ratio is specifically as follows:

[0056]

[0057] Ψ m1 is the test flux value at the same temperature and steady-state condition, Ψ m is the real flux linkage value under the same temperature and steady-state conditions, and Y is the demagnetization ratio.

[0058] The health level is divided into three levels according to the demagnetization ratio: I, II and III. The demagnetization ratio is in the range of 0-5% for I, 5%-10% for II, and greater than 10% for III.

[0059] In this embodiment, the health levels are defined according to different demagnetization ratios, with the demagnetization ratio of level I ranging from 0-5%, the demagnetization ratio of level II ranging from 5%-10%, and the demagnetization ratio of level III ranging from >10%.

[0060] A system for monitoring the health status of a permanent magnet synchronous motor based on magnetic steel temperature, the system comprising a magnetic flux health grading management module, an analysis module, a data acquisition module, a calculation module and a test module, the analysis module is used to analyze the road spectrum of the entire vehicle and find the steady-state working condition, the data acquisition module collects current data in real time, the test module collects test data, the magnetic flux health grading management module stores the health level in NVM or feeds it back to the bus, and the calculation module calculates the demagnetization ratio; the calculation module completes the calculation according to the data of the analysis module, the data acquisition module and the test module, and transmits the calculation result to the magnetic flux health grading management module. The system also includes a magnetic flux observer, which is a current-based magnetic flux observer.

[0061] In this embodiment, the flux health classification management module stores the health level in NVM or feeds it back to the bus, and the quadrature-axis voltage equation and the transient flux equation are derived based on the current flux observer calculation.

[0062] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for monitoring the health status of a permanent magnet synchronous motor based on magnetic steel temperature, characterized in that: The method comprises the following steps: S1. Analyze the vehicle road spectrum to find the stable operating condition with rated input voltage, fixed motor speed and fixed motor torque; S2, powertrain EOL offline test, by changing the rotor temperature and steady-state conditions, the test flux value and convergence error base value under different temperatures and different steady-state conditions are obtained and stored; S3. During normal driving, the current steady-state operating condition is determined. If the rotor is in a steady-state operating condition, the current rotor temperature and flux difference are obtained, and the current true flux value is calculated by combining the test flux value under the corresponding temperature and steady-state operating condition and the convergence error base value; S4. Calculate the demagnetization ratio according to the real magnetic flux value, divide it into corresponding health levels according to the demagnetization ratio, and transmit and store the health levels.

2. The method for monitoring the health status of a permanent magnet synchronous motor based on magnetic steel temperature according to claim 1 is characterized in that: The calculation of the real magnetic flux value is specifically as follows: Ψ m1 and m2 They are the test flux values ​​with different temperatures and the same steady-state conditions, Flux_BaseErr1 and Flux_BaseErr2 are the convergence error base values ​​with different temperatures and the same steady-state conditions, Del_Flux is the flux difference, Ψ m is the actual magnetic flux value.

3. The method for monitoring the health status of a permanent magnet synchronous motor based on magnetic steel temperature according to claim 2 is characterized in that: The method adopts a PID current error closed loop to obtain a flux difference.

4. The method for monitoring the health status of a permanent magnet synchronous motor based on magnetic steel temperature according to claim 3 is characterized in that: The calculation derivation of the flux difference is specifically as follows: is the change of the cross-axis flux, W e is the motor electrical frequency, I d is the direct axis current, I q is the quadrature axis current, is the rotor flux, R s is the stator resistance, L d is the direct-axis inductance, I q (k) is the quadrature axis current sampled at the current moment, I q (k-1) is the quadrature axis current obtained at the last sampling moment, L q is the quadrature-axis inductance, T s To control the switching frequency, U q is the quadrature axis voltage.

5. The method for monitoring the health status of a permanent magnet synchronous motor based on magnetic steel temperature according to claim 1, characterized in that: The rotor temperatures include 20 degC, 80 degC and 120 degC.

6. The method for monitoring the health status of a permanent magnet synchronous motor based on magnetic steel temperature according to claim 1, characterized in that: The calculation of the demagnetization ratio is specifically as follows: Ψ m1 is the test flux value at the same temperature and steady-state condition, Ψ m is the real flux linkage value under the same temperature and steady-state conditions, and Y is the demagnetization ratio.

7. The method for monitoring the health status of a permanent magnet synchronous motor based on magnetic steel temperature according to claim 6, characterized in that: The health level is divided into three levels: I, II and III according to the demagnetization ratio.

8. The method for monitoring the health status of a permanent magnet synchronous motor based on magnetic steel temperature according to claim 7, characterized in that: The demagnetization ratio range is 0-5% as I, the demagnetization ratio range is 5%-10% as II, and the demagnetization ratio range is greater than 10% as III.

9. A system using the permanent magnet synchronous motor health status monitoring method based on magnetic steel temperature according to any one of claims 1 to 8, characterized in that: The system includes a magnetic link health grading management module, an analysis module, a data acquisition module, a calculation module and a test module. The analysis module is used to analyze the road spectrum of the whole vehicle and find the steady-state working condition. The data acquisition module collects current data in real time. The test module collects test data. The magnetic link health grading management module stores the health level in NVM or feeds it back to the bus. The calculation module calculates the demagnetization ratio. The calculation module completes the calculation according to the data of the analysis module, the data acquisition module and the test module, and transmits the calculation result to the magnetic link health grading management module.

10. The system according to claim 9, characterized in that The system further comprises a flux observer, which is a current-based flux observer.

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