electricpete,
Very nice write-ups on how force in electric machines acts on the magnetic material instead of the conductors. You would be happy to know that "Electric Machinery" by Fitzgerald, Kingsley, and Umans makes this point in their textbook. This textbook seems to be a pretty standard...
You are worried about performance when what you should be worried about is the environment. Make a list of all your requirements and send them to motor manufacturers. They will find the right motor for you or they will tell you how much it will cost to make the right motor for you or they will...
Nice article. Have you read James Mevey's thesis "Sensorless Field Oriented Control of Brushless Permanent Magnet Synchronous Motors?" In it he has a nice section discussing terminology. He did a literature search and found the brushless PM motors have been called the following names:
BACM...
Like I said (twice already), you are probably right. It is very common for 4 coils per phase like this to be used to create 4 poles. All I'm saying is that this is not the case in general and one shouldn't confuse the number of coils per phase with the number of poles. What determines the...
theode,
As I said, you are probably right. But you said "They are connected to give a polarity of north pole,south pole,north pole,south pole." How can you see that from the picture? You can't. How each individual coil is connected to each other is unknown at this point. The most probable...
Also, the copper windings and steel that surrounds the windings is usually referred to as the "stator." It generally isn't called an "electromagnet" when talking about a motor.
Sycorax,
This is an AC induction motor ... there are no permanent magnets. The rotor is commonly called a "squirrel cage" rotor. It has laminated steel with cast aluminum in the slots of that steel. The rotor won't tell you how many poles there are. On AC induction motors, the number of...
Well, it's going to depend on the switching frequency of the PWM, the motor speed, the motor inductance and the motor resistance. But in general, during steady state operation, the current will "oscillate" around the 40 Amps. By "oscillate" I mean that the current will rise exponentially...
It's going to do neither of your 2 options. It has to pull 40 Amps because your torque stays the same. And the current isn't going swing from 80 Amps to 0 Amps because the motor's inductance is going to make it resist fast changes to the current.
The test condition for IPX8 only says that it is between the manufacturer and the end user but that it is at least severe as IPX7. So IPX8 doesn't guarantee that they have to run underwater, either.
I would search for IP67 motors rather than "waterproof" or "water tight" motors or any other other key words like that. "Waterproof" means whatever the manufacturer wants it to mean. IP67 means the motor is protected to a depth of 1 meter for at least 30 minutes.
