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.

Working of Permanent Magnet Synchronous Motor

The permanent magnet synchronous motor working principle is similar to the synchronous motor. It depends on the rotating magnetic field that generates electromotive force at synchronous speed. When the stator winding is energized by giving the 3-phase supply, a rotating magnetic field is created in between the air gaps.

This produces the torque when the rotor field poles hold the rotating magnetic field at synchronous speed and the rotor rotates continuously. As these motors are not self-starting motors, it is necessary to provide a variable frequency power supply.

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.

Back-emf waveform:

Back emf is short for back electromotive force but is also known as the counter-electromotive force. The back electromotive force is the voltage that occurs in electric motors when there is a relative motion between the stator windings and the rotor’s magnetic field. The geometric properties of the rotor will determine the shape of the back-emf waveform. These waveforms can be sinusoidal, trapezoidal, triangular, or something in between.

Both induction and PM machines generate back-emf waveforms. In an induction machine, the back-emf waveform will decay as the residual rotor field slowly decays because of the lack of a stator field. However, with a PM machine, the rotor generates its own magnetic field. Therefore, a voltage can be induced in the stator windings whenever the rotor is in motion. Back-emf voltage will rise linearly with speed and is a crucial factor in determining maximum operating speed.