Position Control Closed Loop NdFeB Rare Earth Electric Magnet Motor

What Is The Permanent Magnet Synchronous Motor?

The PERMANENT MAGNET SYNCHRONOUS MOTOR is mainly composed of the stator, rotor, chassis, front-rear cover, bearings, etc. The structure of the stator is basically the same as that of ordinary asynchronous motors, and the main difference between the permanent magnet synchronous motor and other kinds of motors is its rotor.

The permanent magnet material with pre-magnetized (magnetic charged) magnetic on the surface or inside the permanent magnet of the motor, provides the necessary air gap magnetic field for the motor. This rotor structure can effectively reduce the motor volume, reduce loss and improve efficiency.

Analysis of the principle of the technical advantages of permanent magnet motor

The principle of a permanent magnet synchronous motor is as follows: In the motor's stator winding into the three-phase current, after the pass-in current, it will form a rotating magnetic field for the motor's stator winding. Because the rotor is installed with the permanent magnet, the permanent magnet's magnetic pole is fixed, according to the principle of magnetic poles of the same phase attracting different repulsion, the rotating magnetic field generated in the stator will drive the rotor to rotate, The rotation speed of the rotor is equal to the speed of the rotating pole produced in the stator.

Due to the use of permanent magnets to provide magnetic fields, the rotor process is mature, reliable, and flexible in size, and the design capacity can be as small as tens of watts, up to megawatts. At the same time, by increasing or decreasing the number of pairs of rotor permanent magnets, it is easier to change the number of poles of the motor, which makes the speed range of permanent magnet synchronous motors wider. With multi-pole permanent magnet rotors, the rated speed can be as low as a single digit, which is difficult to achieve by ordinary asynchronous motors.

Especially in the low-speed high-power application environment, the permanent magnet synchronous motor can be directly driven by a multi-pole design at low speed, compared with an ordinary motor plus reducer, the advantages of a permanent magnet synchronous motor can be highlighted.

Permanent magnet AC (PMAC) motors have a wide range of applications including:

Industrial Machinery: PMAC motors are used in a variety of industrial machinery applications, such as pumps, compressors, fans, and machine tools. They offer high efficiency, high power density, and precise control, making them ideal for these applications.

Robotics: PMAC motors are used in robotics and automation applications, where they offer high torque density, precise control, and high efficiency. They are often used in robotic arms, grippers, and other motion control systems.

HVAC Systems: PMAC motors are used in heating, ventilation, and air conditioning (HVAC) systems, where they offer high efficiency, precise control, and low noise levels. They are often used in fans and pumps in these systems.

Permanent magnet synchronous motors with internal magnets: Maximum energy efficiency

The permanent magnet synchronous motor with internal magnets (IPMSM) is the ideal motor for traction applications where the maximum torque does not occur at maximum speed. This type of motor is used in applications that require high dynamics and overload capacity. And it is also the perfect choice if you want to operate fans or pumps in the IE4 and IE5 range. The high purchase costs are usually recouped through energy savings over the run time, provided that you operate it with the right variable frequency drive.

Our motor-mounted variable frequency drives use an integrated control strategy based on MTPA (Maximum Torque per Ampere). This allows you to operate your permanent magnet synchronous motors with maximum energy efficiency. The overload of 200 %, the excellent starting torque and the extended speed control range also allow you to fully exploit the motor rating. For fast recovery of costs and the most efficient control processes.

Permanent magnet synchronous motors with external magnets for classic servo applications

Permanent magnet synchronous motors with external magnets (SPMSM) are ideal motors when you need high overloads and rapid acceleration, for example in classic servo applications. The elongated design also results in low mass inertia and can be optimally installed. However, one disadvantage of the system consisting of SPMSM and variable frequency drive is the costs associated with it, as expensive plug technology and high-quality encoders are often used.

The reason why the permanent magnet motor can save electricity:

When the three-phase stator windings of the permanent magnet motor (each with a difference of 120° electrical angle) are fed with a three-phase alternating current with a frequency off, a rotating magnetic field that moves at a synchronous speed will be generated.

In the steady state, the main pole magnetic field rotates synchronously with the rotating magnetic field, so the rotor speed is also the synchronous speed, the stator rotating magnetic field and the main pole magnetic field established by the permanent magnet remain relatively static, and they interact and generate electromagnetic torque, The drive motor rotates and performs energy conversion.

The permanent magnet variable frequency air compressor adopts a high-efficiency permanent magnet motor + inverter (PM motor). The screw host and the high-efficiency permanent magnet motor share the same main shaft. The motor has no bearing. , the transmission efficiency is 100%. This structure eliminates the traditional motor bearing failure point and realizes the motor maintenance-free.

The rare earth permanent magnet material has excellent magnetic properties. After magnetization, it can establish a strong permanent magnetic field without additional energy, which is used to replace the electric excitation field of traditional motors. , Reliable operation, small size, and lightweight. It can not only achieve high performance (such as ultra-high efficiency, ultra-high-speed, and ultra-high response speed) unmatched by traditional electric excitation motors but also can be 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 high-efficiency permanent magnet motor with power electronic technology and microcomputer control technology has improved the performance of the motor and transmission system to a new level:

The high-efficiency permanent magnet variable frequency motor always maintains high efficiency under any load, saving more than 38% energy compared with ordinary motors and more than 10% energy saving to induction variable frequency motors.

After the motor is stopped, it can be started immediately, and it can be started and stopped infinitely without affecting the life of the motor. The starting current does not exceed 100% of the full load current.

Because the permanent magnet variable frequency motor has the advantages of low speed and high output torque, its variable frequency control mode is wider than that of the ordinary induction variable frequency motor. The permanent magnet variable frequency motor is 30% smaller in volume and 35% lighter in weight than motors with the same power, and easier to maintain. Therefore, improving the performance and level of the supporting technical equipment is an important development direction for the motor industry to adjust the industrial structure.

At present, the high-efficiency permanent magnet variable frequency motor is the best choice for a screw air compressor drive motor. It is more efficient and energy-saving than an ordinary three-phase asynchronous variable frequency motor!