effect the coils have on the sensors by adding or subtracting a voltage from the output of the sensors, but only when the coil is on.
You should check out this maglev system called SPM, google it, it is similar to your design, but the stabilization coils are on the bottom of the vehicle and interact with the track levitation magnets. Sorry if you know about this already.
With this design there would be no need for the side-rail magnets. You might be able to use infra-sensors,
I took a look at the SPM design and it looks very good. I was not aware of it. It also uses only permanent magnets in the track, which is nice. The configuration is also homogeneous allong the length of the track, so that you don't need longitudinal position detection. The stabilization force is opposed to my design directly on the main track, which indeed has a cost benefit. Still they don't mention how to detect the lateral deflection.
I have made a second design without iron cores. But the coils influence the sensors too much. I do use Digital Signal Processing, so I might work around this, but it will take more time. Infrared is indeed a good solution to solve this problem.
I indeed drive the coils directly from the OpAmp and they get pretty hot (I don't have the data on this pc thoug). I did not know that I had to use a power-transistor (are those digital transistors or do they amplify linearly with input?).
I think that most power transistors amplifiy linearly, i.e. they are analog, but they can act as digital devices if the input signal is digital. I think they might not get so hot as op-amps (maybe use a heatsink), and might be able to supply more power to your coils, but it depends on what op-amp you are using, I think some op-amps can supply a decent amount of power.
I had a look at your second design, looks good, I guess maybe you might be able to compensate for the
Or you could use an analog hall sensor and a op-amp comparator, with which you could adjust the switching point, which might better. The only problem is that with the hall sensor on the end of the coil, the sensor is affected by the electromagnetic field. But I think this feedback may actually improve stability in a strange way in maglev setups. and I think this way PWM is not needed, just a comparator. But yes, I think the most important thing is to have the hall sensor on the end of the coil.
and measure the gap with an inductive sensor as candeuterio said, or use infrared sensors like I did for my maglev model.
Another thing that I think is important is to have the hall sensor directly on the end of the coil pointing towards the magnets (with the design in this video, with a single side rail of magnets). I think that this is essential for stability. Actually sorry, I made a mistake, like this a digital hall sensor might work.
Then the PWM signal could drive a power transistor that controls the coils. All of this could be done with op-amps. Speaking of op-amps, are you driving the coils direct from the op-amps outputs? Using a power transistor instead to drive the coils would stop the op-amps from heating up I think.
I think that candeuterio's idea of using two side rails might work quite well, or possiibly you could use a single steel rail,
I am impressed by how ambitious your maglev design is, and it is a shame that it does not work fully. I am interested in the same thing as you, I built a model maglev train. It levitates well and the video is on YouTube. The design is simpler.
With your design, I think that both iron-core and air-core coils would probably work, I think that the most important thing is to use analog hall sensors. The analog hall sensor signal could then drive a PWM circuit.
Your design is prone to instability. Iron core of coils are attracted by side magnets even coils are off. Best would be replace side magnets with iron, and hall sensors with inductive proximity sensors. They are more complicated to operate and more expensive. A workaround: two rails in the sideways. One made of steel in line with coils and the other with magnets in line with hall effects. The first rail and coils achieve the guidance, and the second measures the gap to correctly power coils.
Thanks for the tip. I'm guessing proximity sensors only work with a magnet strip? I thought how to measure clearance, but figured that inductivity sensors only work with changing magnetic fields (or with some kind of AC-current. Maybe that is what you are referring to with "more complicated"). Indeed the Iron cores attract. This is something I failed to recognize when designing it. But I notice that the attraction actually provides rotational stability, so it might still be useful.
If the problem persists, a two-line side rail might be an option. It might also just be possible to remove the iron cores and still have enough force (but I won't bet on it).
Inductive gap sensor works inducting a field (coil with alternating current) into ferrous or non ferrous metal and reading fluctuations in the oscillations by a circuit. . Reasonably cheap sensors can been found on ebay, but electronics is the problem. German Transrapid uses this to measure gap. I have various pdfs about maglevs and gap stabilization with railway if you are interested.
for sensing the side to side instability, if the track is a light color and the magnets are dark, by sensing the difference in reflected light.
Good luck with your project!
Sandhi5000 1 year ago
effect the coils have on the sensors by adding or subtracting a voltage from the output of the sensors, but only when the coil is on.
You should check out this maglev system called SPM, google it, it is similar to your design, but the stabilization coils are on the bottom of the vehicle and interact with the track levitation magnets. Sorry if you know about this already.
With this design there would be no need for the side-rail magnets. You might be able to use infra-sensors,
Sandhi5000 1 year ago
@Sandhi5000
I took a look at the SPM design and it looks very good. I was not aware of it. It also uses only permanent magnets in the track, which is nice. The configuration is also homogeneous allong the length of the track, so that you don't need longitudinal position detection. The stabilization force is opposed to my design directly on the main track, which indeed has a cost benefit. Still they don't mention how to detect the lateral deflection.
redefinitionof 1 year ago
Hi Sandhi5000,
I have made a second design without iron cores. But the coils influence the sensors too much. I do use Digital Signal Processing, so I might work around this, but it will take more time. Infrared is indeed a good solution to solve this problem.
I indeed drive the coils directly from the OpAmp and they get pretty hot (I don't have the data on this pc thoug). I did not know that I had to use a power-transistor (are those digital transistors or do they amplify linearly with input?).
redefinitionof 1 year ago
@redefinitionof
I think that most power transistors amplifiy linearly, i.e. they are analog, but they can act as digital devices if the input signal is digital. I think they might not get so hot as op-amps (maybe use a heatsink), and might be able to supply more power to your coils, but it depends on what op-amp you are using, I think some op-amps can supply a decent amount of power.
I had a look at your second design, looks good, I guess maybe you might be able to compensate for the
Sandhi5000 1 year ago
Or you could use an analog hall sensor and a op-amp comparator, with which you could adjust the switching point, which might better. The only problem is that with the hall sensor on the end of the coil, the sensor is affected by the electromagnetic field. But I think this feedback may actually improve stability in a strange way in maglev setups. and I think this way PWM is not needed, just a comparator. But yes, I think the most important thing is to have the hall sensor on the end of the coil.
Sandhi5000 1 year ago
and measure the gap with an inductive sensor as candeuterio said, or use infrared sensors like I did for my maglev model.
Another thing that I think is important is to have the hall sensor directly on the end of the coil pointing towards the magnets (with the design in this video, with a single side rail of magnets). I think that this is essential for stability. Actually sorry, I made a mistake, like this a digital hall sensor might work.
Sandhi5000 1 year ago
Then the PWM signal could drive a power transistor that controls the coils. All of this could be done with op-amps. Speaking of op-amps, are you driving the coils direct from the op-amps outputs? Using a power transistor instead to drive the coils would stop the op-amps from heating up I think.
I think that candeuterio's idea of using two side rails might work quite well, or possiibly you could use a single steel rail,
Sandhi5000 1 year ago
Hi redefinitionof.
I am impressed by how ambitious your maglev design is, and it is a shame that it does not work fully. I am interested in the same thing as you, I built a model maglev train. It levitates well and the video is on YouTube. The design is simpler.
With your design, I think that both iron-core and air-core coils would probably work, I think that the most important thing is to use analog hall sensors. The analog hall sensor signal could then drive a PWM circuit.
Sandhi5000 1 year ago
Your design is prone to instability. Iron core of coils are attracted by side magnets even coils are off. Best would be replace side magnets with iron, and hall sensors with inductive proximity sensors. They are more complicated to operate and more expensive. A workaround: two rails in the sideways. One made of steel in line with coils and the other with magnets in line with hall effects. The first rail and coils achieve the guidance, and the second measures the gap to correctly power coils.
candeuterio 2 years ago
Thanks for the tip. I'm guessing proximity sensors only work with a magnet strip? I thought how to measure clearance, but figured that inductivity sensors only work with changing magnetic fields (or with some kind of AC-current. Maybe that is what you are referring to with "more complicated"). Indeed the Iron cores attract. This is something I failed to recognize when designing it. But I notice that the attraction actually provides rotational stability, so it might still be useful.
redefinitionof 2 years ago
If the problem persists, a two-line side rail might be an option. It might also just be possible to remove the iron cores and still have enough force (but I won't bet on it).
redefinitionof 2 years ago
Inductive gap sensor works inducting a field (coil with alternating current) into ferrous or non ferrous metal and reading fluctuations in the oscillations by a circuit. . Reasonably cheap sensors can been found on ebay, but electronics is the problem. German Transrapid uses this to measure gap. I have various pdfs about maglevs and gap stabilization with railway if you are interested.
candeuterio 2 years ago
Ironless coils is a good option. Old floppy drives have this type of coils.
candeuterio 2 years ago