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Low RPM High Torque 25kw Neodymium Magnet Motor For Plastic Extruder
Brief explanation of permanent magnet motors and advantages:
Permanent magnet motors are electrical machines that use permanent magnets instead of electromagnets to generate the magnetic field required for their operation. These motors have several advantages over traditional motors that use electromagnets:
1. Higher efficiency: Permanent magnet motors have higher efficiency than traditional motors because they have lower losses due to the absence of current in the rotor windings.
2. Better power density: Permanent magnet motors have a higher power density than traditional motors because they can generate a stronger magnetic field with a smaller amount of material.
3. Smaller size and weight: Due to their higher power density, permanent magnet motors can be designed to be smaller and lighter than traditional motors, making them ideal for applications where space and weight are a concern.
4. Lower maintenance: Permanent magnet motors have fewer moving parts than traditional motors, which means they require less maintenance and have a longer lifespan.
5. Better control: Permanent magnet motors have better control because they can respond faster to changes in load and speed, making them suitable for applications that require precise control.
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.
Differences Between The Permanent Magnet Motor And Asynchronous Motor:
01. Rotor Structure
Asynchronous motor: The rotor consists of an iron core and a winding, mainly squirrel-cage and wire-wound rotors. A squirrel-cage rotor is cast with aluminum bars. The magnetic field of the aluminum bar cutting the stator drives the rotor.
PMSM Motor: The permanent magnets are embedded in the rotor magnetic poles, and are driven to rotate by the rotating magnetic field generated in the stator according to the principle of magnetic poles of the same phase attracting different repulsion.
02. Efficiency
Asynchronous motors: Need to absorb current from the grid excitation, resulting in a certain amount of energy loss, motor reactive current, and low power factor.
PMSM Motor: The magnetic field is provided by permanent magnets, the rotor does not need exciting current, and the motor efficiency is improved.
03. Volume And Weight
The use of high-performance permanent magnet materials makes the air gap magnetic field of permanent magnet synchronous motors larger than that of asynchronous motors. The size and weight are reduced compared to asynchronous motors. It will be one or two frame sizes lower than asynchronous motors.
04. Motor Starting Current
Asynchronous motor: It is directly started by power frequency electricity, and the starting current is large, which can reach 5 to 7 times the rated current, which has a great impact on the power grid in an instant. The large starting current causes the leakage resistance voltage drop of the stator winding to increase, and the starting torque is small so heavy-duty starting cannot be achieved. Even if the inverter is used, it can only start within the rated output current range.
PMSM Motor: It is driven by a dedicated controller, which lacks the rated output requirements of the reducer. The actual starting current is small, the current is gradually increased according to the load, and the starting torque is large.
05. Power Factor
Asynchronous motors have a low power factor, they must absorb a large amount of reactive current from the power grid, the large starting current of asynchronous motors will cause a short-term impact on the power grid, and long-term use will cause certain damage to the power grid equipment and transformers. It is necessary to add power compensation units and perform reactive power compensation to ensure the quality of the power grid and increase the cost of equipment use.
There is no induced current in the rotor of the permanent magnet synchronous motor, and the power factor of the motor is high, which improves the quality factor of the power grid and eliminates the need to install a compensator.
06. Maintenance
Asynchronous motor + reducer structure will generate vibration, heat, high failure rate, large lubricant consumption, and high manual maintenance cost; it will cause certain downtime losses.
The three-phase Permanent magnet synchronous motor drives the equipment directly. Because the reducer is eliminated, the motor output speed is low, mechanical noise is low, mechanical vibration is small, and the failure rate is low. The entire drive system is almost maintenance-free.
The three-phase Permanent magnet synchronous motor drives the equipment directly. Because the reducer is eliminated, the motor output speed is low, mechanical noise is low, mechanical vibration is small, and the failure rate is low. The entire drive system is almost maintenance-free.
