The best coil arrangement, with the strongest magnetic field that I have been able to make is with 4 double wound coils all connected in series. It drew about 5 amps. The motor requires that two complete coil units are always connected in series. When two coil units
comprising 8 coils are connected in series the magnetic field becomes very weak. There are many ways that the individual coils can be arranged in series or parallel combinations, but each main coil must be in series with another. When any 2 coil units are energized the power comes in one way and out the opposite way on the next coil unit. As the coils are all wound in the same direction then one coil will be North Pole and the other will be South Pole.
The next best combination I have found has been all coils in each coil unit in parallel. When these coil units are connected in series on the motor and powered up, the current draw is about 15amps, and the MOSFETS and coils run very hot. I have built a set of PCBs to run parallel MOSFETS, but intend to try the above system.comprising 8 coils are connected in series the magnetic field becomes very weak. There are many ways that the individual coils can be arranged in series or parallel combinations, but each main coil must be in series with another. When any 2 coil units are energized the power comes in one way and out the opposite way on the next coil unit. As the coils are all wound in the same direction then one coil will be North Pole and the other will be South Pole.
This is 2 separate MOSFET bridges. Each bridge will be connected to just 2 coils in each coil unit, so the outcome should be the same as my best 4 coil arrangement, and the current draw should total about 10amps on startup. This appears to be a good alternative to parallel MOSFETS.
The system pictured above, using dual power supplies, or 3 phase bridges, has been built and installed. It appears so far to be a good solution for coils. The current draw is about 10 amps max, and the rotor will rotate at about 6 amps. The speed is still very slow, as the rotor is jumping in the magnetic fields, and the guide wheels are causing a lot of friction. I had a better arrangement of stabilizing magnets previously and will return to it. If I can get the rotor to go into fully levitating mode the friction will be zero, the speed will increase and the current draw will drop. It is using about 200 watts at present to move the 30kg rotor.
Another reason this coil setup is appealing is that more coils can be added if required. For instance, if I need to go to a 6 coil set system for more power then I will build 2 more bridges, and then each coil set can be supplied by a separate MOSFET bridge for each of the 4 individual coils and the current draw will simply double. This would also allow magnets and coil sets to become longer in 80mm increments if required. Just another bridge for each added coil pair.
See also another possible simplified drive system using Low Side Mosfets only.
Another reason this coil setup is appealing is that more coils can be added if required. For instance, if I need to go to a 6 coil set system for more power then I will build 2 more bridges, and then each coil set can be supplied by a separate MOSFET bridge for each of the 4 individual coils and the current draw will simply double. This would also allow magnets and coil sets to become longer in 80mm increments if required. Just another bridge for each added coil pair.
See also another possible simplified drive system using Low Side Mosfets only.
