Help with linear motor, magnetization?

In summary, a linear AC generator configuration with a cylinder magnet moving in and out of a coil has three possible configurations for magnetization (axially, diametrically, and radially). However, the best way to produce a significant voltage is by using a magnet with NS-SN-NS configuration, which will reverse the field four times per pass. The distance between the magnet poles should be greater than the axial length of the coil. Additionally, in order to maximize the voltage, the coil should be shorter than the magnet and the distance between the similar poles should be as close as possible. Drawing arrows on the field lines can help visualize the concept.
  • #1
sv3ora
22
0
Hello, attached is a picture of a cylinder magnet moving in and out of a coil, in a linear AC generator configuration.
Below it, there are 3 possible configurations for the magnetization of the magnet (axially/diametrically/radially).
Which of the 3 configurations will produce more voltage on the coil, assuming same motion, magnet mass and magnet strength conditions for all three of them?
 

Attachments

  • mot.png
    mot.png
    2.8 KB · Views: 469
Last edited:
Engineering news on Phys.org
  • #2
The missing fourth way is best.
The second and third will not produce much voltage at all since the field is perpendicular to the coil axis.
The first, axial, will produce a small second harmonic voltage due to divergence of the field at each end of the magnet.

In order to generate a significant voltage you must reverse the magnetic flux through the coil.
A fourth way uses a magnet with NS-SN-NS, which will reverse the field four times per pass.
The distance between the magnet poles should be greater than the axial length of the coil.
 
  • Like
Likes 1 person
  • #3
Baluncore said:
In order to generate a significant voltage you must reverse the magnetic flux through the coil.
A fourth way uses a magnet with NS-SN-NS, which will reverse the field four times per pass.
The distance between the magnet poles should be greater than the axial length of the coil.

Ok so basically you mean like the attached picture?
I am a bit confused. Which of the three you mean?

1. The distance between the individual magnets to be greater than the length of the coil, and all 3 magnets to be moved at the same time back and forth?

2. Or each individual magnet length (magnet cylinder length) to be greater than the length of the coil?

3. Or the three magnets to be forced to touch each other and the total composite magnet length to be greater than the length of the coil?
 

Attachments

  • mot.png
    mot.png
    1.7 KB · Views: 499
  • mot2.png
    mot2.png
    2.7 KB · Views: 501
Last edited:
  • #4
Yes, like your diagrams. But again, the missing fourth way.
4. The three magnets to be forced to be close to each other,
and each individual magnet length (magnet cylinder length) to be greater than the length of the coil,
and all 3 magnets to be moved at the same time back and forth.

There is no advantage to be gained from having two different poles within the coil at the same time as their fields would partially cancel. The length of a magnet is the distance between the poles, so the coil should be shorter than the magnet. The distance between the similar poles can be considered separately. I would make the magnets as close as convenient so the N SS NN S pole pitches were similar, but without too much repulsion.
Draw arrows on your field lines and you will see better how it works.
 
  • #5
Baluncore said:
Yes, like your diagrams. But again, the missing fourth way.
4. The three magnets to be forced to be close to each other,
and each individual magnet length (magnet cylinder length) to be greater than the length of the coil,
and all 3 magnets to be moved at the same time back and forth.

There is no advantage to be gained from having two different poles within the coil at the same time as their fields would partially cancel. The length of a magnet is the distance between the poles, so the coil should be shorter than the magnet. The distance between the similar poles can be considered separately. I would make the magnets as close as convenient so the N SS NN S pole pitches were similar, but without too much repulsion.
Draw arrows on your field lines and you will see better how it works.

Thank you this has been very helpfull.
The last picture in this page https://www.kjmagnetics.com/magneticfield.asp shows a simulation of two magnets repelling and forced to come close. This shows the the closer they come the better, maybe I should try touch the magnets...
 
  • #6
But notice that, as the repelling poles get closer, the field gets closer to the magnets, so the coil outside diameter needs to be as small as possible to be cut by the maximum flux.
 
  • #7
Baluncore said:
But notice that, as the repelling poles get closer, the field gets closer to the magnets, so the coil outside diameter needs to be as small as possible to be cut by the maximum flux.

That seems trully correct! Thanks a lot!
 

1. How does a linear motor work?

A linear motor works by converting electrical energy into linear motion. It consists of a stator, which contains a series of electromagnets, and a moving part called the rotor, which contains permanent magnets. When an electrical current is passed through the stator, it creates a magnetic field that interacts with the magnetic field of the rotor, causing it to move in a linear direction.

2. How do you magnetize a linear motor?

To magnetize a linear motor, the stator must be energized with an electrical current. This creates a magnetic field that magnetizes the permanent magnets in the rotor. The direction of the magnetic field can be changed by reversing the direction of the electrical current, allowing the motor to move in either direction.

3. What are the advantages of using a linear motor?

Linear motors have several advantages over traditional rotary motors. They offer higher efficiency, as there is no need for mechanical components such as gears or belts. They also have a higher power-to-weight ratio and can achieve faster acceleration and deceleration. Additionally, linear motors can be easily integrated into automated systems, making them ideal for use in industries such as manufacturing and transportation.

4. What factors affect the performance of a linear motor?

The performance of a linear motor can be affected by several factors, including the strength and direction of the magnetic field, the weight and design of the moving part, and the precision of the control system. Other factors such as friction, temperature, and external vibrations can also impact the motor's performance.

5. How can I troubleshoot issues with a linear motor?

If a linear motor is not functioning properly, there are a few steps that can be taken to troubleshoot the issue. First, check the power supply and connections to ensure they are functioning correctly. Next, inspect the motor for any physical damage or obstructions. If the motor is still not working, it may be necessary to test the electrical current and magnetic fields to determine the source of the problem. It may also be helpful to consult the manufacturer's manual or seek assistance from a professional.

Similar threads

  • Electrical Engineering
Replies
6
Views
979
  • Electrical Engineering
Replies
14
Views
3K
Replies
14
Views
3K
  • Electrical Engineering
Replies
18
Views
3K
Replies
7
Views
3K
Replies
4
Views
3K
Replies
6
Views
2K
Replies
1
Views
1K
Replies
2
Views
2K
Replies
22
Views
2K
Back
Top