Post by microfarad on Feb 14, 2011 7:38:59 GMT
I think all of the engineering oriented people on this forum should get together to create interesting things. I think a good project would be a compulsator. We would have some hurdles in electromagnetic theory to cross first, but I think we can do it. I could make it out of Legos, for lack of a better idea. I have access to plenty of wire.
First some terminology and groundwork in a system with a rotating bit, a stationary bit, and a bunch of coils...
The rotor is the bit that rotates
The stator is the stationary bit
A field coil is a coil that has current running through it, creating a magnetic field.
An armature coil is a coil that has a current induced in it as it rotates by a magnet/electromagnet, or a magnet/electromagnet rotates by it.
A rotor coil is on the rotor.
A stator coil is on the stator.
A rotor coil may either be a field coil, or an armature coil, the same is true for a stator coil.
We will not use the word armature to talk about the rotor. There is a reason we have the word rotor, it avoids the confusing fact that an armature coil may not be on the rotor, which is often called, in an attempt to confuse little children, an armature.
We will be aware that literature we read may use these terms differently, and we will be careful not to end up confused by this.
We will be jumping headlong into a confusing field. I recommend that you understand the material here www.pearen.ca/dunlite/BrushlessAlternators.pdf (M4 doesn't have Adobe or word, so I made a Google doc docs.google.com/document/d/1ntMq_E4irTN4wYsFqfRI1xr0BYWfPTgczfNmiT93Z2c/edit?hl=en&pli=1#) since much of it is similar to what we will be doing.
You can turn an alternating current into a direct current with diodes.
You should know all the obvious stuff about how inductance works, but I'll re-cap it. I am not insulting your intelligence, just making sure we are on the same page. When you pass a current through a coil of wire, it is difficult for the current to pass until it has built a magnetic field around the coil. When you turn the current off, the magnetic field will collapse, and push a bit more current through in the process. When you pass a coil through a magnetic field, a current will be induced on it.
Here are some of my initial thoughts...
First, you need to spin up the compulsator, make it turn really fast. We'll solve that one later, shouldn't be hard. As it spins, there needs to be little stopping it. That means it isn't a good idea to draw power from it until you flip a switch or something. Coils have an inductance, so if there is a magnetic field being created by field coils, armature coils will slow the spinning down. We don't want that to happen until we... Well... Until we want it to happen, so you have to be able to turn the field off (can't be magnets, has to be coils). The more powerful the field coils are, the faster we can slow down the rotor, meaning the shorter and more powerful our energy pulse is, so we don't want to rely on a weak power source. The optimal solution then is to generate the power for the field coils from another set of coils attached to the same rotor. To clarify, we will have at least one set of field and armature coils. It looks like our compulsator will look a bit like a modified brushless alternator. Let me sleep on this, and I will have more ideas.
First some terminology and groundwork in a system with a rotating bit, a stationary bit, and a bunch of coils...
The rotor is the bit that rotates
The stator is the stationary bit
A field coil is a coil that has current running through it, creating a magnetic field.
An armature coil is a coil that has a current induced in it as it rotates by a magnet/electromagnet, or a magnet/electromagnet rotates by it.
A rotor coil is on the rotor.
A stator coil is on the stator.
A rotor coil may either be a field coil, or an armature coil, the same is true for a stator coil.
We will not use the word armature to talk about the rotor. There is a reason we have the word rotor, it avoids the confusing fact that an armature coil may not be on the rotor, which is often called, in an attempt to confuse little children, an armature.
We will be aware that literature we read may use these terms differently, and we will be careful not to end up confused by this.
We will be jumping headlong into a confusing field. I recommend that you understand the material here www.pearen.ca/dunlite/BrushlessAlternators.pdf (M4 doesn't have Adobe or word, so I made a Google doc docs.google.com/document/d/1ntMq_E4irTN4wYsFqfRI1xr0BYWfPTgczfNmiT93Z2c/edit?hl=en&pli=1#) since much of it is similar to what we will be doing.
You can turn an alternating current into a direct current with diodes.
You should know all the obvious stuff about how inductance works, but I'll re-cap it. I am not insulting your intelligence, just making sure we are on the same page. When you pass a current through a coil of wire, it is difficult for the current to pass until it has built a magnetic field around the coil. When you turn the current off, the magnetic field will collapse, and push a bit more current through in the process. When you pass a coil through a magnetic field, a current will be induced on it.
Here are some of my initial thoughts...
First, you need to spin up the compulsator, make it turn really fast. We'll solve that one later, shouldn't be hard. As it spins, there needs to be little stopping it. That means it isn't a good idea to draw power from it until you flip a switch or something. Coils have an inductance, so if there is a magnetic field being created by field coils, armature coils will slow the spinning down. We don't want that to happen until we... Well... Until we want it to happen, so you have to be able to turn the field off (can't be magnets, has to be coils). The more powerful the field coils are, the faster we can slow down the rotor, meaning the shorter and more powerful our energy pulse is, so we don't want to rely on a weak power source. The optimal solution then is to generate the power for the field coils from another set of coils attached to the same rotor. To clarify, we will have at least one set of field and armature coils. It looks like our compulsator will look a bit like a modified brushless alternator. Let me sleep on this, and I will have more ideas.
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