A method for real-time measurement of temperature of a rotor of a permanent magnet synchronous motor and related equipment

Abstract

The embodiment of the application provides a kind of permanent magnet synchronous motor rotor temperature real-time measurement method and related equipment, to improve the accuracy of permanent magnet synchronous motor rotor temperature real-time measurement, method includes: obtaining E0, E0 is initial temperature T0, permanent magnet synchronous motor under constant speed and no-load operation under real counter electromotive force line voltage value;Obtain E2, E2 is initial temperature T0, permanent magnet synchronous motor under constant speed and constant load operation under frequency converter reading counter electromotive force line voltage value;Frequency converter is read using E3, E3 is current temperature T1, permanent magnet synchronous motor under constant speed and constant load operation under frequency converter reading counter electromotive force line voltage value;According to preset formula, using E0, E2 and E3 calculate the current temperature T1 of the rotor of permanent magnet synchronous motor.The embodiment of the application can realize the real-time measurement of permanent magnet synchronous motor rotor temperature, and measurement result accuracy is high.

Description

Technical Field

[0001] This application relates to the field of motors, specifically to a method and related equipment for real-time measurement of rotor temperature of a permanent magnet synchronous motor. Background Technology

[0002] Compared to asynchronous permanent magnet synchronous motors (PMSMs), PMSMs offer advantages such as higher power density, higher efficiency, and energy savings. With the implementation of new energy consumption standards and the setting of dual-carbon targets, the breadth and depth of PMSM applications in various industrial fields are rapidly increasing. However, the properties of the magnets in PMSMs change with temperature, which significantly affects the motor's output performance.

[0003] When the temperature of a permanent magnet synchronous motor reaches the demagnetization temperature of the magnet grade, the magnet will undergo irreversible demagnetization. Therefore, it is essential to monitor the rotor temperature of a permanent magnet synchronous motor in real time in industrial applications. Summary of the Invention

[0004] This application provides a method and related equipment for real-time measurement of rotor temperature of permanent magnet synchronous motor, which can improve the accuracy of real-time measurement of rotor temperature of permanent magnet synchronous motor.

[0005] The first aspect of this application provides a method for real-time measurement of rotor temperature of a permanent magnet synchronous motor, including:

[0006] E0 is obtained, which is the actual back electromotive force line voltage value of the permanent magnet synchronous motor under constant speed and no-load operation at the initial temperature T0.

[0007] E2 is obtained. E2 is the back electromotive force line voltage value read by the frequency converter of the permanent magnet synchronous motor under constant speed and constant load operation at the initial temperature T0.

[0008] Using the frequency converter to read E3, E3 is the back electromotive force line voltage value read by the frequency converter at the current temperature T1, under constant speed and constant load operation of the permanent magnet synchronous motor. T1 is less than the demagnetization temperature of the magnets of the permanent magnet synchronous motor.

[0009] The current temperature T1 of the rotor of the permanent magnet synchronous motor is calculated using the preset formulas E0, E2 and E3.

[0010] In one implementation of the first aspect of this application, the preset formula includes a difference calculation term, which represents the difference between E3 and E2.

[0011] In one implementation of the first aspect of this application, the preset formula includes a ratio calculation term, which represents the ratio of the difference to E0.

[0012] In one implementation of the first aspect of this application, obtaining E2 specifically includes:

[0013] At an initial temperature T0, a constant load is applied to the permanent magnet synchronous motor for a preset time period, and E2 is read using a frequency converter at a constant speed.

[0014] In one implementation of the first aspect of the embodiments of this application, the method further includes:

[0015] Obtain the constant error value ΔE of the permanent magnet synchronous motor. The constant error value ΔE is the error of reading the back electromotive force line voltage value of the permanent magnet synchronous motor using a frequency converter.

[0016] That is, to obtain the constant error value ΔE, which is the error between the back EMF line voltage value of the permanent magnet synchronous motor read by the frequency converter and the actual back EMF line voltage of the permanent magnet synchronous motor when the motor is under no-load or under constant speed and constant load.

[0017] In one implementation of the first aspect of this application, obtaining E0 specifically includes:

[0018] E0 is obtained using the reverse dragging method.

[0019] In one implementation of the first aspect of this application, the preset formula is:

[0020]

[0021] in This refers to the temperature coefficient of the magnets in a permanent magnet synchronous motor.

[0022] A second aspect of this application provides a real-time rotor temperature measurement device for a permanent magnet synchronous motor, comprising:

[0023] The first acquisition unit acquires E0, which is the actual back electromotive force line voltage value of the permanent magnet synchronous motor under constant speed and no-load operation at the initial temperature T0.

[0024] The second acquisition unit is used to acquire E2, which is the back electromotive force line voltage value read by the inverter of the permanent magnet synchronous motor under constant speed and constant load operation at the initial temperature T0.

[0025] The first reading unit is used to read E3 using the frequency converter. E3 is the back electromotive force line voltage value read by the frequency converter at the current temperature T1 when the permanent magnet synchronous motor is running at constant speed and constant load. T1 is less than the demagnetization temperature of the magnets of the permanent magnet synchronous motor.

[0026] The formula calculation unit is used to calculate the current temperature T1 of the rotor of the permanent magnet synchronous motor according to the preset formula using E0, E2 and E3.

[0027] A third aspect of this application provides a computer device, including:

[0028] Central processing unit, memory, input / output interfaces, and power supply;

[0029] The memory can be either temporary or permanent storage.

[0030] The central processing unit is configured to communicate with the memory and execute instructions in the memory to perform the method of the first aspect.

[0031] A fourth aspect of this application provides a computer-readable storage medium including instructions that, when executed on a computer, cause the computer to perform the method of the first aspect.

[0032] A fifth aspect of this application provides a computer program product containing instructions that, when run on a computer, cause the computer to perform the method of the first aspect.

[0033] A sixth aspect of this application provides a chip system including at least one processor and a communication interface, the communication interface and the at least one processor being interconnected via a line, the at least one processor being used to run a computer program or instructions to perform the method of the first aspect.

[0034] In this embodiment, when calculating the rotor temperature of a permanent magnet synchronous motor in real time, the back electromotive force (EMF) line voltage value E2 of the permanent magnet synchronous motor under constant speed and constant load at the initial temperature T0 is read. This takes into account the error of the back EMF voltage value under constant speed and constant load, rather than simply calculating based on the actual back EMF line voltage value E0 of the permanent magnet synchronous motor under constant speed and no-load operation at the initial temperature T0. This approach considers more comprehensive parameters and reduces calculation errors. This embodiment enables real-time measurement of the rotor temperature of a permanent magnet synchronous motor with high accuracy. Attached Figure Description

[0035] Figures 1 to 2 These are various flowcharts illustrating the real-time rotor temperature measurement method for permanent magnet synchronous motors according to embodiments of this application;

[0036] Figure 3 This is a schematic diagram of the structure of the real-time rotor temperature measurement device for a permanent magnet synchronous motor according to an embodiment of this application;

[0037] Figure 4 This refers to the computer device described in this application embodiment. Detailed Implementation

[0038] Based on existing theories, assuming the magnetic circuit of a permanent magnet synchronous motor is not saturated, the relationship between the remanence of the permanent magnets and the back electromotive force of the permanent magnet synchronous motor is as follows:

[0039] (1)

[0040] E0 is the back electromotive force line voltage value of a permanent magnet synchronous motor measured at its initial temperature T0 using the reverse drag method or other methods. Other methods besides the reverse drag method include, for example, using a hand crank or other tools to drive the permanent magnet synchronous motor on a test bench and analyzing the motor using measuring instruments such as an oscilloscope to obtain E0.

[0041] Br0 represents the remanence of the permanent magnet synchronous motor's magnet at an initial temperature T0. The initial temperature can be ambient, such as 20 degrees Celsius or 26 degrees Celsius, and is not specifically limited. Br0 can be obtained by looking up a table based on the permanent magnet synchronous motor's magnet grade, or it can be measured using specialized instruments.

[0042] E1 is the back electromotive force line voltage value of the permanent magnet synchronous motor at the current temperature T1 during stable operation.

[0043] Br1 represents the residual magnetism of the permanent magnet synchronous motor at the current temperature T1 during stable operation.

[0044] Formula (1) has two unknowns, E1 and Br1.

[0045] like Figure 1 As shown in the figure, this application provides a method for real-time measurement of rotor temperature of permanent magnet synchronous motor, including steps 101 to 104, which is used to improve the accuracy of real-time measurement of rotor temperature of permanent magnet synchronous motor.

[0046] 101. Obtain E0, which is the actual back electromotive force line voltage value of the permanent magnet synchronous motor under constant speed and no-load operation at the initial temperature T0.

[0047] 102. Obtain E2. E2 is the back electromotive force line voltage value read by the frequency converter at the initial temperature T0, when the permanent magnet synchronous motor is running at constant speed and constant load.

[0048] 103. Use the frequency converter to read E3. E3 is the back electromotive force line voltage value read by the frequency converter at the current temperature T1 when the permanent magnet synchronous motor is running at a constant speed and constant load. T1 is less than the demagnetization temperature of the magnets of the permanent magnet synchronous motor.

[0049] 104. Calculate the current rotor temperature T1 of the permanent magnet synchronous motor using the preset formula, E0, E2 and E3.

[0050] It should be noted that there are no timing restrictions between steps 101, 102 and 103.

[0051] In this embodiment, when calculating the rotor temperature of a permanent magnet synchronous motor in real time, the back electromotive force (EMF) line voltage value E2 of the permanent magnet synchronous motor under constant speed and constant load at the initial temperature T0 is read. This takes into account the error of the back EMF line voltage value under constant speed and constant load, rather than simply calculating based on the actual back EMF line voltage value E0 of the permanent magnet synchronous motor under constant speed and no-load operation at the initial temperature T0. This approach considers more comprehensive parameters and reduces calculation errors. This embodiment enables real-time measurement of the rotor temperature of a permanent magnet synchronous motor with high accuracy.

[0052] It should be noted that the back electromotive force line voltage value E2 of the permanent magnet synchronous motor under constant speed and constant load operation can be read using a frequency converter at the work site, factory, or laboratory, or it can be measured using other instruments in the factory or laboratory. The frequency converter used to measure E2 and E3 can be the same frequency converter.

[0053] This application provides a method for real-time measurement of rotor temperature of a permanent magnet synchronous motor. The theoretical derivation process of the measurement is as follows.

[0054] The inverter is set to open-loop control, and the operating speed is set to ensure the permanent magnet synchronous motor operates at a constant speed. The permanent magnet synchronous motor is controlled to operate at an initial temperature T0, and a constant load is applied to the permanent magnet synchronous motor for a preset time Δt. At this time, the back electromotive force line voltage value E2 of the permanent magnet synchronous motor is read from the inverter, where Δt ≤ 15s.

[0055] The open-loop control back EMF algorithm of the frequency converter contains errors. At an initial temperature T0, the back EMF line voltage value E2 read by the frequency converter when the permanent magnet synchronous motor is running at constant speed and constant load differs from the actual back EMF line voltage value E0 when the permanent magnet synchronous motor is running at constant speed and no load by a constant error value ΔE.

[0056] ΔE=E2-E0 (2).

[0057] At the current temperature T1, the true back electromotive force (EMF) line voltage value E1 of the permanent magnet synchronous motor under constant speed and constant load operation as a function of temperature can be obtained by using the difference between the back EMF line voltage E3 calculated in real time during the constant speed and constant load operation of the permanent magnet synchronous motor under frequency converter control and the constant error value ΔE.

[0058] E1=E3-ΔE (3).

[0059] From formulas (3) and (2), we can obtain formula (4) as follows:

[0060] E1 = E3 + E0 - E2 (4)

[0061] Substituting formula (4) into formula (1), we can obtain the expression for Br1, formula (5) as follows.

[0062] (5)

[0063] Br1 refers to the residual magnetism of a permanent magnet synchronous motor at the current temperature T1 during constant speed and constant load operation.

[0064] Formula (6) represents the relationship between remanence and temperature, as follows:

[0065] (6)

[0066] in The temperature coefficient of the magnets in a permanent magnet synchronous motor is typically selected as -0.09% to -0.1%.

[0067] Formula (7) is derived from formula (6) as follows:

[0068] (7).

[0069] Substituting formula (5) into formula (7), we obtain formula (8) as follows:

[0070] (8)

[0071] This application embodiment is used to realize real-time measurement of rotor temperature in steady-state open-loop control of a permanent magnet synchronous motor. Utilizing the open-loop control algorithm of the frequency converter, the back electromotive force value of the permanent magnet synchronous motor is obtained in real time and calculated to obtain the rotor temperature, thus preventing demagnetization of the permanent magnet synchronous motor magnets.

[0072] It should be noted that formula (8) is not limited to the form given in the embodiments of this application, and its equivalent transformations can also be used, which are not limited here.

[0073] like Figure 2 As shown in the figure, this application embodiment provides a method for real-time calculation of rotor temperature of a permanent magnet synchronous motor, including steps 201 to 207. Here, the initial temperature is selected as room temperature, denoted as T0.

[0074] 201. At room temperature T0, Br0 can be obtained by looking up the magnet grade of the permanent magnet synchronous motor in the table.

[0075] 202. Obtain the true back electromotive force line voltage value E0 of the permanent magnet synchronous motor by means of the reverse drag method at room temperature T0.

[0076] 203. Apply a constant speed and constant load to the permanent magnet synchronous motor T0 at room temperature within a preset time Δt under the open-loop control of the frequency converter, and read the back EMF line voltage value E2 obtained under the open-loop control through the frequency converter.

[0077] 204. At approximately room temperature T0, when the permanent magnet synchronous motor is running at constant speed and constant load, the back electromotive force line voltage value read by the frequency converter has a constant error value ΔE compared with the stable and true back electromotive force line voltage value E0. ΔE = E2 - E0.

[0078] 205. The true back electromotive force (EMF) line voltage value E1 of a permanent magnet synchronous motor under stable operating conditions can be obtained by using the difference between the back EMF line voltage E3, calculated in real time during the stable and continuous operation of the permanent magnet synchronous motor under the control of the frequency converter, and ΔE.

[0079] E1 = E3 - ΔE.

[0080] 206. The true back electromotive force (EMF) line voltage value E1 of a permanent magnet synchronous motor under stable operating conditions, which varies with temperature, can be obtained by using the difference between the back EMF line voltage E3 and ΔE, which are calculated in real time during the stable and continuous operation of the permanent magnet synchronous motor under the control of the frequency converter.

[0081] E1 = E3 - ΔE = E3 - E2 + E0.

[0082] 207. Rotor temperature of permanent magnet synchronous motor under stable operating conditions

[0083] .

[0084] This application provides a method for real-time calculation of rotor temperature of a permanent magnet synchronous motor, using a 15kW permanent magnet synchronous motor as an example.

[0085] The permanent magnet synchronous motor has a rated speed of 3600 rpm and a single-layer distributed winding. =-0.095%.

[0086] The initial temperature T0 was determined to be 30.1℃. Using the reverse drag method, the actual back electromotive force line voltage E0 of the permanent magnet synchronous motor when running at the rated speed of 3600rpm was found to be 299.2V.

[0087] The steps of the reverse drag method are as follows: First, use an external power source to accelerate the permanent magnet synchronous motor and maintain it at a specific speed, so that the permanent magnet synchronous motor is in "generating" mode; then, use an oscilloscope or power analyzer to measure the actual back electromotive force line voltage E0 of the permanent magnet synchronous motor. The external power source can be another permanent magnet synchronous motor, an internal combustion engine, etc.

[0088] Using an open-loop inverter to control a permanent magnet synchronous motor running at 3600 rpm, a 40 N·m load is applied to this 15 kW permanent magnet synchronous motor within a preset time period Δt of 5 seconds. At this time, the back electromotive force line voltage value fed back by the inverter is E2 = 310.0 V. The constant error value ΔE = E2 - E0 = 310.0 V - 299.2 V = 10.8 V.

[0089] When a 40 N•m load is applied to this 15 kW permanent magnet synchronous motor, and the motor reaches a steady-state temperature rise at 3600 rpm, the back electromotive force E3 fed back by the frequency converter is 299.0 V. At this time, the actual back electromotive force line voltage of the permanent magnet synchronous motor is E1 = E3 - ΔE = 288.2 V.

[0090] To verify the accuracy of the embodiments of this application, the back electromotive force line voltage of the permanent magnet synchronous motor at steady-state temperature was measured to be 287.5V using the reverse drag method within 15 seconds. The steady-state temperature is the current temperature T1.

[0091] As can be seen from the above, the deviation between the indirectly monitored back EMF value and the actual linear back EMF value under steady-state temperature of the permanent magnet synchronous motor is [value missing]. .

[0092] Set E0=299.2V, E3=299.0V, E2=310.0V, Substituting -0.095% and T0 = 30.1 degrees Celsius into formula (8), we can obtain T1 = 68.8℃. The calculated T1 is the rotor temperature value of the permanent magnet synchronous motor under stable operating conditions.

[0093] The back electromotive force line voltage value can also be called the line back electromotive force.

[0094] like Figure 3 As shown in the figure, this application embodiment provides a real-time rotor temperature measurement device for a permanent magnet synchronous motor, comprising:

[0095] The first acquisition unit 301 is used to acquire E0, which is the actual back electromotive force line voltage value of the permanent magnet synchronous motor under constant speed and no-load operation at the initial temperature T0.

[0096] The second acquisition unit 302 is used to acquire E2, which is the back electromotive force line voltage value read by the inverter of the permanent magnet synchronous motor under constant speed and constant load at the initial temperature T0.

[0097] The first reading unit 303 is used to read E3 using the frequency converter. E3 is the back electromotive force line voltage value read by the frequency converter under constant speed and constant load operation of the permanent magnet synchronous motor at the current temperature T1. T1 is less than the demagnetization temperature of the magnets of the permanent magnet synchronous motor.

[0098] Formula calculation unit 304 is used to calculate the current temperature T1 of the rotor of the permanent magnet synchronous motor using E0, E2 and E3 according to a preset formula.

[0099] In one implementation, the second acquisition unit 302 is specifically used to apply a stable load to the permanent magnet synchronous motor within a preset time period at an initial temperature T0, and read E2 using a frequency converter under the load.

[0100] The real-time rotor temperature measurement device for permanent magnet synchronous motors also includes:

[0101] The error acquisition unit is used to acquire the constant error value ΔE of the permanent magnet synchronous motor. The constant error value ΔE is the error of reading the back electromotive force line voltage value of the permanent magnet synchronous motor using the frequency converter.

[0102] The first acquisition unit 301 is specifically used to acquire E0 using the reverse dragging method.

[0103] like Figure 4 As shown in the illustration, this application also provides a computer device 400, including:

[0104] Central processing unit 401, memory 404, input / output interface 403, and power supply 402;

[0105] Memory 404 is either a short-term storage memory or a persistent storage memory;

[0106] The central processing unit 401 is configured to communicate with the memory 404 and execute instructions stored in the memory 404 to perform actions such as... Figures 1 to 2 The method in the illustrated embodiment.

[0107] This application also provides a computer-readable storage medium, which includes instructions that, when executed on a computer, cause the computer to perform actions such as... Figures 1 to 2 The method in the illustrated embodiment.

[0108] This application also provides a computer program product containing instructions that, when run on a computer, cause the computer to perform actions such as... Figures 1 to 2 The method in the illustrated embodiment.

[0109] This application also provides a chip system, which includes at least one processor and a communication interface. The communication interface and the at least one processor are interconnected via a circuit. The at least one processor is used to run computer programs or instructions to perform tasks such as... Figures 1 to 2 The method in the illustrated embodiment.

[0110] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0111] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between apparatuses or units through some interfaces, and may be electrical, mechanical, or other forms.

[0112] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0113] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0114] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A method for real-time measurement of rotor temperature of a permanent magnet synchronous motor, characterized in that, include: E0 is obtained, where E0 is the actual back electromotive force line voltage value of the permanent magnet synchronous motor under constant speed and no-load operation at the initial temperature T0. E2 is obtained, where E2 is the back electromotive force line voltage value read by the frequency converter of the permanent magnet synchronous motor under constant speed and constant load operation at the initial temperature T0. Using a frequency converter to read E3, E3 is the back electromotive force line voltage value read by the frequency converter under the constant speed and constant load of the permanent magnet synchronous motor at the current temperature T1, where T1 is less than the demagnetization temperature of the magnets of the permanent magnet synchronous motor. The current temperature T1 of the rotor of the permanent magnet synchronous motor is calculated using the preset formula, E0, E2 and E3.

2. The method for real-time measurement of rotor temperature of a permanent magnet synchronous motor according to claim 1, characterized in that, The preset formula includes a difference calculation term, which represents the difference between E3 and E2.

3. The method for real-time measurement of rotor temperature of a permanent magnet synchronous motor according to claim 2, characterized in that, The preset formula includes a ratio calculation term, which represents the ratio of the difference to E0.

4. The method for real-time calculation of rotor temperature of a permanent magnet synchronous motor according to any one of claims 1 to 3, characterized in that, The acquisition of E2 specifically includes: At the initial temperature T0, a constant load is applied to the permanent magnet synchronous motor within a preset time period, and the E2 is read using the frequency converter at the constant speed.

5. The method for real-time measurement of rotor temperature of a permanent magnet synchronous motor according to any one of claims 1 to 3, characterized in that, The method further includes: Obtain the constant error value ΔE of the permanent magnet synchronous motor, wherein the constant error value ΔE is the error of reading the back electromotive force line voltage value of the permanent magnet synchronous motor using the frequency converter.

6. The method for real-time calculation of rotor temperature of a permanent magnet synchronous motor according to any one of claims 1 to 3, characterized in that, The acquisition of E0 specifically includes: The E0 is obtained using the reverse dragging method.

7. The method for real-time measurement of rotor temperature of a permanent magnet synchronous motor according to any one of claims 1 to 3, characterized in that, The preset formula is: in is the temperature coefficient of the magnets in the permanent magnet synchronous motor.

8. A real-time rotor temperature measurement device for a permanent magnet synchronous motor, characterized in that, include: The first acquisition unit is used to acquire E0, which is the actual back electromotive force line voltage value of the permanent magnet synchronous motor under constant speed and no-load operation at the initial temperature T0. The second acquisition unit is used to acquire E2, which is the back electromotive force line voltage value of the permanent magnet synchronous motor read by the frequency converter under the constant speed and constant load operation at the initial temperature T0. The first reading unit is used to read E3 using a frequency converter. E3 is the back electromotive force line voltage value of the permanent magnet synchronous motor read by the frequency converter under the constant speed and constant load operation at the current temperature T1. T1 is less than the demagnetization temperature of the magnets of the permanent magnet synchronous motor. The formula calculation unit is used to calculate the current temperature T1 of the rotor of the permanent magnet synchronous motor according to a preset formula using E0, E2 and E3.

9. A computer device, characterized in that, include: Central processing unit, memory, input / output interfaces, and power supply; The memory can be either temporary or permanent storage. The central processing unit is configured to communicate with memory and execute instructions in memory to perform the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes instructions that, when executed on a computer, cause the computer to perform the method as described in any one of claims 1 to 7.

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