The development history of the magnetic field distribution on the surface of the multi-pole magnetized magnetic ring FE-2100R magnetic distribution measuring instrument
In the permanent magnet motor industry, the use of permanent magnet materials to design stators or rotors is quite common. The need to accurately measure the surface magnetic field distribution of a designed permanent magnet stator or rotor is becoming more and more important. Accurate measurement and related analysis are also very important. In the late 1990s (the earliest product in China was Ms. Meng Xianhong), related product design and manufacturing began.
Multi-pole magnetized magnetic ring (including radial inner and outer magnetization, plane axial magnetization, etc.), accurately test the distribution waveform of the magnetic field (specifically include the magnetic pole amplitude, the width of the magnetic pole, the half-width, the duty cycle, etc. ) Is very practical. Deviation analysis, harmonic wave analysis, 3D magnetic field distribution and visual magnetic field analysis are becoming more and more important.
The test principle of the magnetic field distribution of the multi-pole magnetized magnetic ring is quite simple. According to the description of the test process, people often call it a rotating Gauss meter. In the age when computer control is not developed, the sample is fixed on a turntable with polar coordinates. The manual record of the upper rotation test can be traced back to earlier (early Taiwan products). After 2000, the electric rotation control platform products were launched one after another, which improved the test efficiency and test accuracy.
It is a pity that, in the production process of related products, manufacturers have neglected the most critical technical indicator of the magnetic distribution tester, that is, the rotation concentricity. Since 2001, a large number of magnetic distribution testers have been listed one after another, domestically manufactured There are no fewer than 10 companies, and there are more than 8 foreign companies (Japan, South Korea, Germany, etc.) that I know about. The ignorance of the concentricity index is destined to plummet the price of the modified product. From the domestic first multi-pole magnetized magnetic ring magnetic field distribution tester (Dongfang Chenjing RMT-301), it has successively introduced the simple device of Shandong Meng Da, China Academy of Metrology, Tianyu, Lianzhong, Hirano, Xinglong, and Jinda have successively launched to meet the testing needs of users at home and abroad.
During this period, I was also fortunate to carry out repairs to similar products in Japan. During the process of calibrating the test probe, I found that the Japanese equipment also had insufficient concentricity. The equipment calibration can only rely on the magnetic ring issued by them to approach adjustments (perhaps They leave the factory corresponding to good concentricity). In the later process of a large number of tests and adjustments on the surface magnetic distribution measuring instrument, it was found that making a good magnetic field distribution measuring instrument is not a simple rotating Gauss meter. The problem that manufacturers should actively solve is how to continuously improve the rotational concentricity of the product (including Japanese products) instead of requiring users to use flexible probes to close the magnetic ring under test. In the previous log, I have performed the analysis and calculation of the concentricity deviation, and I will not repeat it here. In fact, it is easy to understand if you think about it. The rotation concentricity is not good, and the flexible probe is used to stick the magnetic ring and the Hall plate. Moving back and forth in the normal direction will directly affect the peak data (decrease), and the most fatal thing is the test deviation of the magnetic pole width.
Contact with many magnetizing fixture design engineers in the same industry. They have been tired for only 10 years. The magnetizing fixture is constantly adjusted according to the report of the magnetic distribution tester. The processing industry is required to continuously improve the cutting accuracy and the winding process. The result is still not ideal. In fact, if he tests the concentricity, these questions will be raised to the equipment supplier as soon as possible.
The equipment supplier will not tell the user the defects of the equipment before the equipment problem is solved, and will only cater to the user to make the desired product. For example, the user proposes whether to use a magnetic material for the chuck. Then change the chuck head to copper, aluminum alloy, or ask the chuck manufacturer to directly process aluminum alloy. And think of different ways to improve the concentricity of rotation, as much as possible to make the concentricity of rotation as good as possible. The actual effect is indeed not as good as expected.
The main problems are as follows:
1. Choose a low-end chuck. The rotational concentricity index of the chuck itself at around 300 yuan is not enough. No matter how artificial adjustments are made, it will be of little significance. To make a good product, at least choose the same chuck as the concentricity meter; . .
2. What is more difficult is how to ensure the selection of concentricity after connecting the shaft and the chuck. Concentricity meter manufacturers have a good way, but the price of using the concentricity meter to configure the magnetic field test software will exceed the user's price acceptance level (unless In the military industry, I would recommend this method, the rotation concentricity can reach 0.01mm).
3. Since 2011, I checked foreign counterparts. Except for the concentricity of German Magre products, which was better than 0.05mm, there were really no relevant indicators. But what German Magre products provide is a rotating platform without a chuck, which means that you can do a good job of the fixture in the later stage, and whether you meet the concentricity has nothing to do with them.
The establishment of Hunan Yongyi Technology Co., Ltd. was to lead a group of like-minded friends to solve the problems they found in the manufacturing process of magnetic measurement equipment, and to improve the level of domestic magnetic measurement technology. At the same time, it is expected that the company will gradually improve the test The technical leadership will establish the corporate brand and image as soon as possible. At the beginning of 2012, Bosch Electric put forward strict requirements in this regard, and launched an assessment in this regard in China, and the company took over the production and development of the required products. After nearly half a year of hard work, a platform with a rotational concentricity of less than 0.05mm was manufactured in 2012. After vibration experiments and long-term experimental operation by users, it met the requirements of rotational concentricity and became the first in the industry to include concentricity indicators in the table. The company is a manufacturer of magnetic distribution test equipment, and has been recognized by companies such as MagQueen Magnetics, DJI Technology, and Long Magnetic Technology. Since the product was sold in 2012, the Chinese and English version of the software was completed in 2014. The product has been exported to Taiwan, Thailand, Iran, Russia, Singapore, the United States and other countries, becoming a product that participates in international competition.
Users' requirements for testing are constantly improving, and measurement equipment also needs continuous development and improvement. Testing software also needs continuous addition of functions to ensure the advanced nature of the product. For the testing of multi-pole magnetic rings, the current requirements are far more than just the initial inspection waveform, amplitude and magnetic pole width. The meaning of the test waveform is continuously transmitted to the user, so that the user can have a more comprehensive understanding of the motor design based on the waveform, and it will be more meaningful. The first-generation test software of Hunan Yongyi Technology Co., Ltd. has conducted harmonic analysis on the magnetic field distribution waveform, which is used to help and guide the improvement of the motor manufactured by using the magnetization waveform in the later period. The second-generation will improve the 3D test. It is a visual magnetic field (independent intellectual property), any angle of vision and azimuth angle rotation, which is convenient for users to find distribution defects. FE-2100R series surface magnetic field distribution measuring instrument covers multi-pole ring surface magnetic distribution measurement, linear surface magnetic distribution measurement, planar surface magnetic distribution measurement and spatial magnetic field distribution measurement. It is an excellent product to achieve accurate measurement of surface magnetic field distribution. It has become a high-quality product in the surface magnetic field distribution test equipment for multi-pole magnetic rings and magnets. It provides accurate magnetic field distribution data for motor design and can fully evaluate the magnetization accuracy of magnets. It has been adopted by many well-known companies.
The following is an explanation of harmonic analysis. The French mathematician J.-B.-J. Fourier put forward when studying the boundary value problem of partial differential equations. Thus greatly promoted the development of the theory of partial differential equations. In China, Cheng Minde was the first to systematically study multivariate triangular series and multivariate Fourier series. He first proved the uniqueness theorem of the spherical sum of multivariate trigonometric series and revealed many characteristics of the Ries-Bochner spherical average of multivariate Fourier series. Fourier series has greatly promoted the development of the theory of partial differential equations. It has important applications in mathematical physics and engineering.
The harmonic frequency is an integral multiple of the fundamental frequency. According to the French mathematician Fourier (M. Fourier) analysis principle, any repetitive waveform can be decomposed into a sine wave containing the fundamental frequency and a series of harmonics that are multiples of the fundamental. Weight. At the same time, according to the different harmonic frequencies, it can be divided into:
Odd order: The harmonics whose rated frequency is an odd multiple of the fundamental frequency are called "odd harmonics", such as the 3rd, 5th, and 7th harmonics.
Even-order: The harmonics whose rated frequency is an even multiple of the fundamental frequency are called "even-order harmonics", such as the 2, 4, 6, and 8 harmonics.
In the multi-pole magnetic ring surface magnetic distribution test device, we have introduced a harmonic analysis report. The mathematical transformation formula of the Fourier transform is: f(t)=a0+a1sin(ωt+θ1)+ a2sin(2ωt+ θ2) +a3sin(3ωt+θ3)+ ... +ansin(nωt+θn)
In the formula, a0 represents the direct current component. For a multi-pole magnetized rotor, it is expressed as an analysis of the total amount of asymmetry of NS magnetic poles. a1 represents the amplitude of the fundamental wave, ωt represents the frequency of the fundamental wave, θ1 represents the phase angle of the fundamental wave, and an represents the fundamental wave.
At the same time, it can be seen that the harmonics are all sine waves, and each harmonic has a different frequency (integer multiples of the fundamental wave), and corresponds to the relative amplitude and phase angle.
Generally speaking, odd harmonics cause more harm than even harmonics. For rotating generators and motors, additional losses are generated in the stator windings, rotor circuits and iron cores due to harmonic currents or harmonic voltages, thereby reducing the efficiency of power generation and transmission and electrical equipment. What is more serious is that harmonic oscillations are prone to The steam turbine generator produces an oscillating torque, and the noise of the motor is correspondingly increased, and it may even cause mechanical resonance, causing the turbine blades to twist and produce fatigue cycles, causing the equipment to fail to work normally.
1. Test interface of multi-pole magnetic ring meter magnetic distribution test device
Note: The blue waveform is the actual test waveform; the red waveform is the ideal sine waveform; the green double-line peak upper limit and lower limit range are qualified or not.
Hunan Yongyi Technology's complete board XY coordinate test report sample
Complete board polar coordinate test report
Full version of the harmonic test report:
Single 3D report sample (angle of view 40º, azimuth angle 18º)
Attachment 1: Observe whether the magnetic poles are tilted (angle of view 90º, azimuth angle 0º, which is equivalent to spreading the magnetic poles in the circumferential direction)
Attachment 2: Observe the fluctuation of the radial magnetic field amplitude (angle of view 0º, azimuth angle 0º)
Attachment 3: Observe any angle (FE-2100R multi-pole test software is a self-developed 3D graphics software. The user can freely control the viewing angle and azimuth angle to rotate the 3D waveform, observe any position of the magnetic field, and find the defect position. A holographic visual magnetic field test equipment, the refresh speed is at the leading level in the industry).