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What factors need to be considered when choosing a permanent magnet motor?   ① Consider Your Application Requirements The first step in choosing a neodymium magnet motor is to consider your application requirements. What power output do you need? What speed and torque requirements does your application have? Answering these questions will help you narrow down your options and choose a motor that will work for your specific application.   ② Cost Of course, the cost is always a factor when making any purchase—and that includes choosing a motor. Permanent magnet motors can range in price from a few hundred dollars to several thousand. Make sure to compare prices from different suppliers before making your decision. But also keep in mind that sometimes, you get what you pay for. So don’t choose the cheapest option without doing your research first.   ③ Size/Weight The size and weight of the motor will be determined by your power requirements and the application in which it will be used. If space is at a premium, then you’ll need to factor that into your decision-making process.   ④ Maintenance Neodymium magnet motors are generally very low maintenance, but it’s still important to consider how easy or difficult it will be to perform routine maintenance tasks like oil changes and brake repairs.   ⑤ Efficiency Requirements Efficiency is another important consideration when choosing a PM motor. Motors with higher efficiency ratings will use less energy, which can save you money in the long run. When comparing efficiency ratings, be sure to compare apples to apples by looking at motors that are the same size and have similar power outputs.   ⑥ Durability Permanent magnet motors are designed for long-term use, but some models are more durable than others. If your application is particularly demanding, then you’ll need to make sure that you choose a motor that can stand up to the rigors of your specific application.   ⑦ Mounting Options How will the motor be mounted? Some motors come with multiple mounting options while others are limited to just one or two possibilities. You’ll need to make sure that the motor you choose can be mounted in the way that’s required for your application   ⑧ Pick the Right Supplier Finally, make sure you pick the right supplier. Working with a reputable supplier who has experience in designing and manufacturing PM motors will help ensure that you get a quality product that meets your specific needs.

1. Rare Earth Permanent Magnet Motor – The Future Of Motor Rare earth permanent magnet motor is a new type of permanent magnet motor that appeared in the early 1970s. Due to the excellent magnetic properties of rare earth permanent magnet materials, they can establish a strong permanent magnetic field without external energy after magnetization. Rare earth permanent magnet motor not only has high efficiency but also has a simple structure and reliable operation. It can also be small in size and light in weight.   Made into special motors that can meet specific operating requirements, such as elevator traction motors, special motors for automobiles, etc. The combination of rare earth permanent magnet motors with power electronics technology and microcomputer control technology has improved the performance of the motor and transmission system to a new level. Improving the performance and level of the supporting technical equipment is an important development direction for the motor industry to adjust the industrial structure. Rare earth permanent magnet motors are widely used in almost every field of aviation, aerospace, national defense, equipment manufacturing, industrial and agricultural production, and daily life. It includes permanent magnet synchronous motors, permanent magnet generators, DC motors, brushless DC motors, AC permanent magnet servo motors, permanent magnet linear motors, special permanent magnet motors, and related control systems, covering almost the entire motor industry. 2. Rare Earth Permanent Magnet Motor Policy Support On November 22, 2021, the Ministry of Industry and Information Technology and the State Administration for Market Regulation jointly issued the “Motor Energy Efficiency Improvement Plan (2021-2023)”, proposing that by 2023, the annual output of high-efficiency and energy-saving motors will reach 170 million kilowatts, and the proportion of the high-efficiency and energy-saving motors in service reached more than 20%, and the annual electricity saving was 49 billion kWh. The document clearly mentions that “For fans, pumps, compressors, machine tools, and other general-purpose equipment, encourage the use of electric motors with energy efficiency level 2 and above. For variable load operating conditions, promote variable-frequency permanent magnet motors with energy efficiency level 2 and above.” According to the 2013 version of the “Permanent Magnet Synchronous Motor” standard, the current production of permanent magnet motors is distributed in the first-level and second-level energy consumption intervals; combined with the “Motor Energy Efficiency Limits and Energy Efficiency Grades” (GB 18613-2020) and “Motor Energy Efficiency Improvement Plan”, only some high-performance NdFeB rare earth permanent magnet motors can reach the efficiency of more than 95% of the first-level energy consumption standard (corresponding to IE5), and the rest of the rare-earth permanent magnet motors belong to the second-level energy consumption standard.   At present, rare earth permanent magnet motors can save more than 10% of electricity and increase their efficiency to more than 95%. Using rare earth permanent magnet synchronous motor, the power saving rate of reactive power can reach 85%, and the power saving rate of active power can reach 23%~25%. The power-saving effect is remarkable. 3. Why Should We Vigorously Develop Rare Earth Permanent Magnet Energy-Saving Motors? (1) Industrial Motors Are The Areas That Consume The Most Electricity In Society. In 2020, China’s motor holdings will be about 4 billion kilowatts, and the total power consumption will be about 4.8 trillion kwh, accounting for 64% of the total electricity consumption of the whole society. Among them, the total power consumption of motors in the industrial field will be 3.84 trillion kWh, Accounting for 75% of industrial electricity consumption, every 1% increase in the energy efficiency of motors in the industrial field can save about 38.4 billion kWh of electricity per year, and a 3% increase in energy efficiency is equivalent to the annual power generation of the Three Gorges. The State Council issued the “2030 Carbon Peak Action Plan”, which focuses on promoting energy conservation and efficiency enhancement of key energy-consuming equipment, focusing on motors, fans, pumps, compressors, transformers, heat exchangers, industrial boilers and other equipment to comprehensively improve energy efficiency standard. (2) High-Efficiency And Energy-Saving Motors Refer To General-Purpose Standard Motors With High Efficiency (meeting above the second-level standard of the new motor energy efficiency standard). In May 2020, China announced the latest motor energy efficiency standard “GB18613-2020 Motor Energy Efficiency Limits and Energy Efficiency Grades”, the standard is officially implemented on June 1, 2021, and energy-efficient motors below IE3 (international standard) were forced to stop production. Motor types include three-phase asynchronous motors, rare earth permanent magnet motors, etc. Traditional asynchronous motors can be increased by increasing materials (increasing the outer diameter of the iron core, increasing the size of the stator slot, increasing the weight of copper wires, and using silicon steel sheets with good magnetic permeability). However, due to its basic working principle, it is difficult to improve the efficiency of traditional asynchronous motors. For example, some IE4 and IE5 energy-efficient motors prefer to use permanent magnet mode. (3) More Importantly, Compared With Asynchronous Motors, Rare Earth Permanent Magnet Motors Have Natural Energy-Saving Advantages. 1) Energy saving:   Different from the asynchronous motor, the rotor of the permanent magnet motor does not need an excitation current, and the energy saving is about 15%-20%. 2) High efficiency:   The efficiency of permanent magnet motors is 2-19 percentage points higher than that of traditional motors. 3) Rare earth permanent magnet motor has a simple structure and low failure rate. 4) Long life:   The rotor of the permanent magnet motor adopts an embedded sealed structure, which is beneficial to reduce friction and oxidation during rotation and improve the stability and life of the motor.(4) The Recovery Cycle Of Replacing Rare Earth Permanent Magnet Motors Is About 1-2 Years, And The Economic Benefits Are Actually Obvious.   4. The differences between rare earth permanent magnet motors and traditional motor   A permanent magnet motor is a DC/AC synchronous motor in which the stator is a permanent magnet and only the rotor is a coil. The stator of an ordinary motor is a coil (electromagnet). 1) The Nature Of The Magnetic Field. After the permanent magnet motor is made, it can maintain its magnetic field without external energy; traditional motors need electric current to have a magnetic field. 2) Applicable Occasions. Traditional motors need to drive a reduction mechanism to achieve high torque, while rare earth permanent magnet motors can replace the reduction mechanism to achieve direct drive. 3) The Permanent Magnet Motor Has Small Vibration And Good Running Stability. 4) High Power Density And Efficiency. Compared with ordinary motors, permanent magnet motors have high power density, which mainly means that permanent magnet motors are small in size and large in power generation or output. Compared with ordinary motors, energy saving can reach 20%-40%. The rotor structure of the permanent magnet motor is different from that of the ordinary motor. The permanent magnet poles are installed on the rotor of the permanent magnet motor; the excitation coil is installed on the rotor of the ordinary motor, and the magnetic field needs to be supplied with current. Compared with traditional motors, any speed point saves power, especially at low speeds. 5) Small Size, Lightweight, Low Temperature Rise The permanent magnet motor has a simple structure. Due to the use of high-performance permanent magnets to provide the magnetic field, the air gap magnetic field of the permanent magnet motor is greatly enhanced compared with ordinary motors, while the volume and weight of permanent magnet motors are greatly reduced compared with ordinary motors. Sizes and shapes are also flexible. The non-electric excitation of the rotor means that there is no loss and heat generation. Therefore, the temperature rise of permanent magnet motors is generally very low. 6) Lower Failure Rate, Widely Used Due to the use of high-performance rare earth permanent magnet materials to provide the magnetic field, the failure rate is lower and the use is more common. 7) Large Starting Torque And Good Performance Since the rotor winding does not work when the permanent magnet motor works normally, the rotor winding can be designed to fully meet the requirements of high starting torque, for example, from 1.8 times to 2.5 times, or even greater. 5. How Long Is The Life Of Rare Earth Permanent Magnet Motor? Will The Magnetism Weaken Over Time? The service life of the permanent magnet motor is generally 15-20 years, and the service life of the motor mainly depends on the maintenance of the user. In addition, the quality of the permanent magnet motor’s use environment, and the factors such as electricity, magnetism, heat, vibration, and other factors that the motor receives during use will affect the life of the permanent magnet synchronous motor! General magnets have a service life. When used for a certain number of years, the magnetism will weaken, but the magnetic properties of NdFeB permanent magnet materials change very little with time, and rare earth permanent magnets are within the design life of the motor (10-20 years). The magnetic performance attenuation is less than 3%. Under the existing motor design and electronic control technology, it has little impact on the overall performance of the motor. Reasons For Demagnetization Of Permanent Magnet Motors: 01. Improper Selection Of Magnetic Steel Grades If the calculation of the motor design is not accurate enough, and a lower grade is wrongly selected, such as the permanent magnet of 180°C should be selected but 155°C is wrongly selected, there may be such a situation: the initial test record index of the test process is very good, As the motor gradually tends to be thermally stable, the relevant indicators of the motor begin to deteriorate, and deviate from the design expectations more and more. At a certain moment, the current increases sharply, the inverter stops quickly, and an overcurrent code is displayed. Test the no-load characteristics of the motor again, indicating that the motor has lost its magnetism, and the magnetic steel must be replaced. 02. Overheating The Demagnetization Problem Overheating loss of magnetism is a sensitive topic, and the decrease in the magnetic properties of magnets can also lead to overcurrent and overheating problems. If the influence of the magnetic properties of the magnetic steel is excluded and only the thermal factor is considered, it can be determined that there are two situations in which the phenomenon of overheating demagnetization will occur: first, the circulation ventilation path in the motor is unreasonable, which violates the natural law of cold and heat conduction, resulting in localized heat accumulation; second, The heat load of the winding is too high, and the heat generation exceeds the heat exchange level of the motor heat exchange system. 03. The Problem Of Excessive Demagnetization Current When the motor is running, when the load current exceeds the anti-demagnetization ability of the magnet, it will cause irreversible demagnetization of the magnet, which will further increase the load current and aggravate the irreversible demagnetization of the magnet. This reciprocation accelerates irreversible demagnetization until demagnetization. How To Prevent The Demagnetization Of Permanent Magnet Motors? 01. Correct Selection Of Permanent Magnet Motor Power: Demagnetization is related to the power selection of permanent magnet motors. Correct selection of PM motor power can prevent or delay demagnetization. The main reason for the demagnetization of the permanent magnet synchronous motor is that the temperature is too high, and the overload is the main reason for the high temperature. Therefore, a certain margin should be left when selecting the power of the permanent magnet motor. According to the actual situation of the load, generally, about 20% is more appropriate. 02. Avoid Heavy Load Starting And Frequent Starting: Permanent magnet synchronous motors try to avoid direct starting or frequent starting of heavy loads. During the starting process, the starting torque is oscillating, and in the valley section of the starting torque, the stator magnetic field is demagnetizing the rotor magnetic pole. Therefore, try to avoid the heavy load and frequent starting of the permanent magnet synchronous motor. 03. Improve The Design: (1) Appropriately increase the thickness of the permanent magnet: From the perspective of permanent magnet synchronous motor design and manufacture, the relationship between armature reaction, electromagnetic torque, and permanent magnet demagnetization should be considered. Under the combined action of the magnetic flux produced by the torque winding current and the magnetic flux produced by the radial force winding, the permanent magnets on the rotor surface easily cause demagnetization. Under the condition that the air gap of the motor remains unchanged, to ensure that the permanent magnet does not demagnetize, the most effective method is to appropriately increase the thickness of the permanent magnet. (2) There is a ventilation groove circuit inside the rotor to reduce the temperature rise of the rotor: If the temperature of the rotor is too high, the permanent magnet will cause irreversible loss of magnetism. In the structural design, the internal ventilation circuit of the rotor can be designed to directly cool the magnetic steel. Not only reduces the temperature of the magnetic steel, but also improves its efficiency.

There are many types of PMSM motors, which can be divided into sine wave pmm motors and trapezoidal wave pmm motors according to the waveform of the stator winding induced electromotive force.   In the structure of touch screen maintenance in the composition of machine tool equipment, the stator of the sine wave permanent magnet synchronous motor used is composed of three-phase windings and iron cores.   The armature windings are often connected in Y-shape and short-distance distributed windings are used: the air gap field is designed as a sine wave, to generate a sine wave counter electromotive force; the rotor uses permanent magnets instead of electric excitation. 1. Motor Control Method At present, there are mainly two control methods for three-phase synchronous motors, one is other control type (also known as frequency open-loop control); the other is self-control type (also known as frequency closed-loop control).   The other control method mainly adjusts the speed of the rotor by independently controlling the frequency of the N#I-part power supply.   It does not need to know the position information of the rotor, and an open-loop control scheme with a constant voltage-frequency ratio is often used. The self-controlled permanent magnet synchronous motor also adjusts the rotor speed by changing the frequency of the external power supply. Unlike the other control type, the change of the frequency of the external power supply is related to the position information of the rotor. The higher the rotor speed, the higher the stator energization frequency. The rotor speed is adjusted by changing the frequency of the applied voltage (or current) to the stator winding. Because the self-controlled synchronous motor does not have the out-of-step and oscillation problems of the other-controlled synchronous motor, and the permanent magnet of the permanent magnet synchronous motor does not have brushes and commutators, which reduces the volume and quality of the rotor and improves the response speed and speed range of the system, so we use a self-controlled AC permanent magnet synchronous motor. When the three-phase symmetrical power supply is added to the three-phase symmetrical winding, a synchronous rotating stator magnetic field will naturally be generated. The rotational speed of the synchronous motor rotor is strictly synchronized with the frequency of the external power supply and has nothing to do with the size of the load. 2. The Principle Of PMM Motor The working principle of pmsm motor is the same as that of the synchronous motor. PMSMs are widely used now, and like induction motors, they are commonly used AC motors. The characteristics are: during steady-state operation, there is a constant relationship between the rotor speed and the grid frequency n=ns=60f/p, and ns is called synchronous speed. If the frequency of the power grid is constant, the speed of the synchronous motor is constant at a steady state regardless of the size of the load. Operating as a generator is the most important operating mode of a synchronous motor, and operating as a motor is another important operating mode of a synchronous motor. The power factor of the synchronous motor can be adjusted. In the occasions where speed regulation is not required, the application of a large synchronous motor can improve the operating efficiency. In recent years, small synchronous motors have been used in variable frequency asynchronous motors, also known as induction motors, which are AC motor that generates electromagnetic torque through the interaction of the air gap rotating magnetic field and the induced current of the rotor winding, thereby realizing the conversion of electromechanical energy into mechanical energy.   The Working Process Of PM Motors Is As Follows: ① Establishment Of The Main Magnetic Field Of The Pm Motors: The excitation winding is supplied with a DC excitation current to establish an excitation magnetic field between polarities, that is, the main magnetic field is established. ② Current-Carrying Conductor Of Pm Motors: The three-phase symmetrical armature winding acts as a power winding and becomes the carrier of induced potential or induced current. ③ Cutting Motion Of Pm Motors: The prime mover drags the rotor to rotate (input mechanical energy to the motor), and the excitation magnetic field between polarities rotates with the shaft and cuts the stator winter phase winding in sequence (equivalent to the conductor of the winding reverse cutting the excitation field ) ④ Generation Of The Alternating Potential Of Pm Motors: Due to the relative cutting motion between the armature winding and the main magnetic field, a three-phase symmetrical alternating potential with periodic changes in size and direction will be induced in the armature winding. AC power can be provided through the lead wire. ⑤ Alternation And Symmetry Of Pm Motors: Due to the alternating polarity of the rotating magnetic field, the polarity of the induced potential is alternated, and the three-phase symmetry of the induced potential is guaranteed due to the symmetry of the armature winding.