A method for measuring air gap magnetic flux waveform of permanent magnet synchronous motor

Abstract

The present invention discloses a method for measuring the air gap flux density waveform of a permanent magnet synchronous motor, which relates to the field of fault diagnosis. The method comprises: modeling and simulating the permanent magnet synchronous motor to be measured to obtain a theoretical air gap flux density waveform of the permanent magnet synchronous motor to be measured; determining a Gaussmeter probe to be installed based on the theoretical air gap flux density waveform and preset screening conditions; installing the Gaussmeter probe to be installed on the stator teeth of the permanent magnet synchronous motor to be measured as a measuring Gaussmeter probe; measuring the air gap flux density data of the permanent magnet synchronous motor to be measured using a Gaussmeter instrument connected to the measuring Gaussmeter probe; inputting the air gap flux density data into an oscilloscope, and displaying the air gap flux density waveform of the permanent magnet synchronous motor to be measured on the oscilloscope. In this way, more diagnostic strategies are developed for fault diagnosis of high-power-density permanent magnet synchronous motors used in industry, ensuring the safety and reliability of permanent magnet synchronous motor operation.

Description

Technical Field

[0001] The present invention relates to the field of fault diagnosis, and in particular to a method for measuring an air gap magnetic flux waveform of a permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motors (PMSMs) offer advantages such as high power density, high efficiency, a large torque-to-inertia ratio, and a wide speed regulation range. Currently, PSMs are widely used in wind power generation, aerospace, marine applications, and electric vehicles. During operation, PSMs can experience faults such as inter-turn short circuits, eccentricity, and demagnetization.

[0003] Demagnetization and eccentricity faults in permanent magnet synchronous motors are primarily characterized by the motor's air gap flux waveform. Measuring the air gap flux of a permanent magnet synchronous motor using a Hall effect sensor can effectively diagnose these faults. However, this method is only applicable to permanent magnet synchronous motors with a relatively small air gap flux density. Industrial permanent magnet synchronous motors, however, typically have relatively large air gap flux densities due to their pursuit of high power density. The existing Hall effect sensor's magnetic flux density measurement range is insufficient to meet the requirements of industrial permanent magnet synchronous motors.

[0004] Patent content

[0005] The purpose of the embodiments of the present invention is to provide a method for measuring the air gap flux density waveform of a permanent magnet synchronous motor, so as to develop more diagnostic strategies for fault diagnosis of high power density permanent magnet synchronous motors used in industry and ensure the safety and reliability of the operation of the permanent magnet synchronous motor.

[0006] The specific technical solutions are as follows:

[0007] In a first aspect of the present invention, a method for measuring the air gap flux density waveform of a permanent magnet synchronous motor is provided, the method comprising:

[0008] Modeling and simulating the permanent magnet synchronous motor to be measured to obtain a theoretical air gap magnetic flux waveform of the permanent magnet synchronous motor to be measured;

[0009] Determine the Gaussmeter probe to be installed according to the theoretical air gap magnetic flux waveform and preset screening conditions;

[0010] Installing the Gaussmeter probe to be installed on the stator teeth of the permanent magnet synchronous motor to be measured as a measuring Gaussmeter probe;

[0011] Measuring the air gap magnetic flux data of the permanent magnet synchronous motor to be measured by using the measuring gaussmeter probe and the gaussmeter instrument connected to the measuring gaussmeter probe;

[0012] The air gap flux density data is input into an oscilloscope, and the air gap flux density waveform of the permanent magnet synchronous motor to be measured is displayed by the oscilloscope.

[0013] Optionally, determining a Gaussmeter probe to be installed according to the theoretical air gap magnetic flux waveform and preset screening conditions includes:

[0014] Determining the peak-to-peak value of the theoretical air gap magnetic flux waveform according to the theoretical air gap magnetic flux waveform diagram;

[0015] Select a Gaussmeter probe with a measuring range greater than the peak-to-peak value of the wave as the Gaussmeter probe to be installed;

[0016] Optionally, the step of installing the Gaussmeter probe to be installed on the stator teeth of the permanent magnet synchronous motor to be measured as a measuring Gaussmeter probe includes:

[0017] Determining a preset sub-tooth on the permanent magnet synchronous motor to be measured according to the fault type to be diagnosed;

[0018] According to the width, thickness and length of the Gaussmeter probe to be installed, a groove is formed on the preset sub-tooth to serve as an installation groove;

[0019] The gaussmeter probe to be installed is installed in the installation groove as a measuring gaussmeter probe.

[0020] Optionally, determining a preset sub-tooth on the permanent magnet synchronous motor to be measured according to the fault type to be diagnosed includes:

[0021] If the fault type to be diagnosed is a demagnetization fault of a permanent magnet synchronous motor, any stator tooth in the lower half plane of the stator cross-section plane of the permanent magnet synchronous motor to be measured is selected as a preset stator tooth;

[0022] If the fault type to be diagnosed is an eccentricity fault of a permanent magnet synchronous motor, the stator teeth at the 3 o'clock direction and the 9 o'clock direction of the permanent magnet synchronous motor to be measured are selected as preset stator teeth.

[0023] Optionally, after installing the Gaussmeter probe to be installed in the installation slot, the method further includes:

[0024] The lead wire of the measuring Gaussmeter probe is electromagnetically shielded.

[0025] An embodiment of the present invention provides a method for measuring the air gap flux density waveform of a permanent magnet synchronous motor. The method includes modeling and simulating the permanent magnet synchronous motor to be measured to obtain a theoretical air gap flux density waveform diagram of the permanent magnet synchronous motor to be measured; determining a Gaussmeter probe to be installed based on the theoretical air gap flux density waveform diagram and preset screening conditions; installing the Gaussmeter probe to be installed on the stator teeth of the permanent magnet synchronous motor to be measured as a measurement Gaussmeter probe; measuring the air gap flux density data of the permanent magnet synchronous motor to be measured using the measurement Gaussmeter probe; inputting the air gap flux density data into an oscilloscope, and displaying the air gap flux density waveform of the permanent magnet synchronous motor to be measured using the oscilloscope. The Gaussmeter probe can measure waveforms of larger flux densities, that is, it can measure the air gap flux density waveform of a permanent magnet synchronous motor with high power density used in industry. This method opens up more diagnostic strategies for fault diagnosis of high power density permanent magnet synchronous motors used in industry, ensuring the safe and reliable operation of the permanent magnet synchronous motors. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flow chart of a method for measuring the air gap flux density waveform of a permanent magnet synchronous motor provided by an embodiment of the present invention;

[0027] Figure 2 A flow chart of another method for measuring the air gap flux density waveform of a permanent magnet synchronous motor provided by an embodiment of the present invention;

[0028] Figure 3 Three-view diagram of a Gaussmeter probe provided in an embodiment of the present invention installed on a stator tooth;

[0029] Figure 4 A diagram showing the position of the stator teeth of a permanent magnet synchronous motor Gaussmeter probe installed in a demagnetization experiment provided by an embodiment of the present invention;

[0030] Figure 5 Three views of the Gaussmeter probe installation structure for a 4-pole, 36-slot permanent magnet synchronous motor provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be described below with reference to the accompanying drawings in the embodiments of the present invention.

[0032] See also Figure 1 , Figure 1 A flow chart of a method for measuring the air gap flux density waveform of a permanent magnet synchronous motor provided in an embodiment of the present invention, the method may include the following steps:

[0033] S101, modeling and simulating the permanent magnet synchronous motor to be measured to obtain a theoretical air gap magnetic flux waveform of the permanent magnet synchronous motor to be measured.

[0034] S102, determining a Gaussmeter probe to be installed based on a theoretical air gap magnetic flux waveform and preset screening conditions.

[0035] S103: Installing a Gaussmeter probe to be installed on a stator tooth of the permanent magnet synchronous motor to be measured, as a measuring Gaussmeter probe.

[0036] S104 , measuring the air gap magnetic flux density data of the permanent magnet synchronous motor to be measured by using a measuring gaussmeter probe and a gaussmeter instrument to which the measuring gaussmeter probe is connected.

[0037] S105 , inputting the air gap flux density data into an oscilloscope, and displaying the air gap flux density waveform of the permanent magnet synchronous motor to be measured via the oscilloscope.

[0038] The air-gap flux density waveform measurement method for a permanent magnet synchronous motor provided by the present invention enables the measurement of relatively large flux density waveforms using a Gaussmeter probe. This allows the measurement of air-gap flux density waveforms for high-power density industrial permanent magnet synchronous motors. This opens up additional diagnostic strategies for fault diagnosis of these high-power density industrial permanent magnet synchronous motors, ensuring their safe and reliable operation.

[0039] In one implementation, the permanent magnet synchronous motor to be measured can be modeled and simulated using Maxwell software.

[0040] In one embodiment, step S102 includes:

[0041] Step 1: determine the peak-to-peak value of the theoretical air gap magnetic flux waveform according to the theoretical air gap magnetic flux waveform diagram.

[0042] Step 2: Select a Gaussmeter probe with a range greater than the peak-to-peak value as the Gaussmeter probe to be installed.

[0043] In one embodiment, see Figure 2 ,exist Figure 1 On the basis of, step S103 includes:

[0044] S1031 : Determine a preset sub-tooth on the permanent magnet synchronous motor to be measured according to the fault type to be diagnosed.

[0045] S1032, according to the width, thickness and length of the Gaussmeter probe to be installed, a groove is cut on the pre-set sub-tooth to serve as an installation groove;

[0046] S1033, installing a gaussmeter probe to be installed in the installation slot as a measurement gaussmeter probe.

[0047] In one implementation, the Gaussmeter probe has a certain length, width, and thickness. Since the air gap of a permanent magnet synchronous motor is generally less than 1 mm, if the Gaussmeter probe is simply attached to the stator surface, the probe will be damaged due to insufficient space. Slots can be made on the stator teeth, and the Gaussmeter probe can be installed in the slots to prevent the probe from being damaged. The size of the slots can be determined based on the actual width and thickness of the Gaussmeter probe. After the stator teeth are slotted, the magnetic resistance of the silicon steel sheet is much smaller than the air gap magnetic resistance, so the effect of the slots on the air gap magnetic flux is small and can be ignored. However, the slot depth should be minimized to reduce the impact on the air gap magnetic flux. For the axial length of the Gaussmeter probe on the stator teeth, it is necessary to avoid the influence of the end effect of the motor on the air gap magnetic flux measured by the permanent magnet synchronous motor, and extend it as much as possible into the axial direction of the stator teeth.

[0048] After slotting the stator teeth, apply glue to the slots and insert the gaussmeter probe into them. Finally, secure the probe to the stator tooth surface with glue to prevent it from falling off or shaking during high-speed rotor movement. The gaussmeter probe should be placed perpendicular to the radial direction of the permanent magnet synchronous motor. This mounting structure effectively measures the radial flux density of the AC magnetic field in the air gap above the stator teeth. Securely securing the gaussmeter probe facilitates accurate measurement of the radial flux density of the permanent magnet synchronous motor.

[0049] See also Figure 3 , Figure 3 Three-view diagram of the Gaussmeter probe installed on the stator teeth.

[0050] In one embodiment, step S1031 includes:

[0051] If the fault type to be diagnosed is a demagnetization fault of a permanent magnet synchronous motor, any stator tooth in the lower half plane of the stator cross-section plane of the permanent magnet synchronous motor to be measured is selected as a preset stator tooth.

[0052] If the fault type to be diagnosed is an eccentricity fault of a permanent magnet synchronous motor, the stator teeth at the 3 o'clock direction and the 9 o'clock direction of the permanent magnet synchronous motor to be measured are selected as the preset stator teeth.

[0053] In one implementation, a Gaussmeter probe may be installed on a specific stator tooth according to different rotor faults of the permanent magnet synchronous motor.

[0054] In one implementation, a gaussmeter probe can be installed to diagnose demagnetization failures in permanent magnet synchronous motors (PMSMs). Since the air gap distance remains unchanged when a PMSM demagnetization failure occurs, the gaussmeter probe can be installed in the lower half of the motor's stator cross-section whenever possible, given its weight. This means that the stator teeth in the lower half of the PMSM stator cross-section to be measured can be selected as the pre-set stator teeth.

[0055] In another implementation, to address eccentricity in a permanent magnet synchronous motor, since this fault changes the air gap of the motor, two gaussmeter probes must be installed. The connecting line must pass through the center of the stator cross-section plane. Considering the weight of the gaussmeter probes, the two probes can be installed at the 3 and 9 o'clock positions of the permanent magnet synchronous motor. With the motor mounting base oriented at 6 o'clock, the stator teeth at 3 and 9 o'clock to be measured can be identified and used as the preset stator teeth.

[0056] In one embodiment, after the Gaussmeter probe to be installed is installed in the installation slot, the measuring Gaussmeter probe may be electromagnetically shielded.

[0057] In one implementation, when the gaussmeter probe is connected to the instrument, the measured magnetic flux density of the permanent magnet synchronous motor is inaccurate because part of the probe wire surrounds the end winding and is affected by the rotating magnetic flux lines of the permanent magnet synchronous motor. Therefore, the probe needs to be electromagnetically shielded. This can be achieved by wrapping the lead wire of the gaussmeter probe with copper foil to provide electromagnetic shielding and ensure the accuracy of the measured magnetic flux density of the permanent magnet synchronous motor.

[0058] In one embodiment, a demagnetization experiment is performed on a specific permanent magnet synchronous motor with 4 pole pairs and 36 slots as an example.

[0059] See also Figure 4 , Figure 4 Schematic diagram of the location of the stator teeth for installing the Gaussmeter of the permanent magnet synchronous motor for demagnetization experiments.

[0060] See also Figure 5 , Figure 5 Three-view drawing of the Gaussmeter probe installation structure for a 4-pole, 36-slot permanent magnet synchronous motor.

[0061] Because the air gap width of the demagnetization test motor is uniform, multiple probes are not required. A single probe is sufficient to obtain the magnetic flux density waveform corresponding to each permanent magnet surface in the motor. Since only one probe is required, the Gaussmeter probe can be installed in the slot at the bottom of the motor's stator teeth. This allows the probe to adhere completely to the stator teeth and prevent it from falling due to its own gravity, thus reducing the influence of gravity on the probe.

[0062] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0063] Each embodiment in this specification is described in a related manner. The same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A method for measuring the air gap magnetic flux waveform of a permanent magnet synchronous motor, characterized in that: The method comprises: Modeling and simulating the permanent magnet synchronous motor to be measured to obtain a theoretical air gap magnetic flux waveform of the permanent magnet synchronous motor to be measured; Determine the Gaussmeter probe to be installed according to the theoretical air gap magnetic flux waveform and preset screening conditions; Installing the Gaussmeter probe to be installed on the stator teeth of the permanent magnet synchronous motor to be measured as a measuring Gaussmeter probe; Measuring the air gap magnetic flux data of the permanent magnet synchronous motor to be measured by using the measuring gaussmeter probe and the gaussmeter instrument connected to the measuring gaussmeter probe; Inputting the air gap flux density data into an oscilloscope, and displaying the air gap flux density waveform of the permanent magnet synchronous motor to be measured by the oscilloscope; Determining the Gaussmeter probe to be installed based on the theoretical air gap magnetic flux waveform and preset screening conditions includes: Determining the peak-to-peak value of the theoretical air gap magnetic flux waveform according to the theoretical air gap magnetic flux waveform diagram; Select a Gaussmeter probe with a measuring range greater than the peak-to-peak value of the wave as the Gaussmeter probe to be installed; The gaussmeter probe to be installed is installed on the stator teeth of the permanent magnet synchronous motor to be measured as a measuring gaussmeter probe, comprising: Determining a preset sub-tooth on the permanent magnet synchronous motor to be measured according to the fault type to be diagnosed; According to the width, thickness and length of the Gaussmeter probe to be installed, a groove is formed on the preset sub-tooth to serve as an installation groove; The gaussmeter probe to be installed is installed in the installation groove as a measuring gaussmeter probe.

2. The method for measuring the air gap flux density waveform of a permanent magnet synchronous motor according to claim 1, characterized in that: After installing the Gaussmeter probe to be installed in the installation slot, the method further includes: The lead wire of the measuring Gaussmeter probe is electromagnetically shielded.

3. The method for measuring the air gap flux density waveform of a permanent magnet synchronous motor according to claim 2, characterized in that: Determining a preset sub-tooth on the permanent magnet synchronous motor to be measured according to the fault type to be diagnosed includes: If the fault type to be diagnosed is a demagnetization fault of a permanent magnet synchronous motor, any stator tooth in the lower half plane of the stator cross-section plane of the permanent magnet synchronous motor to be measured is selected as a preset stator tooth; If the fault type to be diagnosed is an eccentricity fault of a permanent magnet synchronous motor, the stator teeth at the 3 o'clock direction and the 9 o'clock direction of the permanent magnet synchronous motor to be measured are selected as preset stator teeth.

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