Number of Turns vs. Wire Gauge (BLDC Motor)

In summary: The thermal load is produced by ##I^2R## losses. Thinner wires have higher R per foot and more feet if you increase the number of turns.
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George-M
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For the same mass of copper wire, would more turns or greater thickness create a stronger magnetic field from a coil?
Summary: For the same mass of copper wire, would more turns or greater thickness create a stronger magnetic field from a coil?

So I am attempting to make a brush less DC motor, and I am wondering whether the coils would create a greater magnetic force if there are more turns or if the wire is thicker. If the copper wire is thicker, there will have to be fewer turns. If the copper wire is thinner, there will be more turns. I do believe that wire of a greater thickness has less resistance. Imagine I have two coils of copper wire with the same mass of identical copper wire; one of greater thickness but fewer turns, and the other of less thickness but more turns. My question is: which would create the strongest magnetic force? (Extended distance/ range of magnetic field is not necessary, because the rotor will be extremely close to the coils anyway). Please pardon my lack of technical terminology.
 
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  • #2
the magnetic field has nothing to do with the size of the wire but everything to do with the number of turns. More turns, greater field intensity.
 
  • #3
Thicker wire permits higher currents. So for the same current thinner wire and more turns allows a more powerful field.

The limit is thermal; how much heat can you dissipate from the coils at a reasonable temperature. The thermal load is produced by ##I^2R## losses. Thinner wires have higher R per foot and more feet if you increase the number of turns.

A BLDC motor is designed to mate with a BLDC controller. You have to consider how much current the controller can provide.

As in most designs, everything interacts with everything else and there are many tradeoffs.

Reading this may help you;
https://www.edn.com/design/sensors/4406682/Brushless-DC-Motors---Part-I--Construction-and-Operating-Principles
 
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Likes Asymptotic and DaveE
  • #4
Thank you both ever so much. I am going to use thinner wire because, I have a design that should keep temperatures low as is.
 

1. What is the relationship between number of turns and wire gauge in a BLDC motor?

The number of turns and wire gauge in a BLDC motor are directly related. As the number of turns increases, the wire gauge must decrease in order to maintain the same overall size and weight of the motor. This is because a higher number of turns requires more wire, which takes up more space and adds weight to the motor. Therefore, a lower wire gauge is necessary to accommodate the increased number of turns.

2. How does the number of turns affect the torque and speed of a BLDC motor?

The number of turns in a BLDC motor has a direct impact on both the torque and speed of the motor. A higher number of turns will result in a higher torque output, but a lower maximum speed. Conversely, a lower number of turns will result in a lower torque output, but a higher maximum speed. This is because the number of turns determines the strength of the magnetic field, which in turn affects the motor's torque and speed.

3. What is the significance of wire gauge in a BLDC motor?

The wire gauge in a BLDC motor is crucial for determining the motor's performance and efficiency. A thicker wire gauge can handle more current and therefore produce more torque, but it also adds weight and size to the motor. On the other hand, a thinner wire gauge can result in a lighter and smaller motor, but it may not be able to handle as much current and therefore produce less torque.

4. How do the number of turns and wire gauge affect the overall efficiency of a BLDC motor?

The number of turns and wire gauge have a significant impact on the overall efficiency of a BLDC motor. A higher number of turns and a lower wire gauge can result in a more efficient motor, as it can produce more torque while minimizing the weight and size of the motor. However, finding the perfect balance between number of turns and wire gauge is crucial, as using too many turns or too thin of a wire can lead to decreased efficiency and potentially damage the motor.

5. Can the number of turns and wire gauge be customized for specific applications?

Yes, the number of turns and wire gauge in a BLDC motor can be customized for specific applications. Different applications may require different torque and speed outputs, and the number of turns and wire gauge can be adjusted accordingly to achieve the desired performance. However, it is important to consider the trade-offs between torque, speed, and efficiency when customizing the number of turns and wire gauge for a BLDC motor.

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