All parts of the motor, excluding magnets, solenoid wrapping wire, and hall effect sensors, were printed with a Makerbot Replicator 2. The video shows bldc motor working pdf completed working motor.
This instructable is available as a pdf here along with cad files and the program for motor control. Feel free to use the files, comment, change the design, or do whatever you please with this! A 3D printer, an arduino microcontroller, and access to basic electronic tools like a multimeter, an oscilloscope, a power supply, and electrical components are necessary for this project. The complete list of parts and tools I used. Table 1 shows the cost to build the motor.
Electrical components such as resistors and capacitors were not included as the cost was negligible relative to the total cost of the motor. It should be noted that cost reduction was not a top priority, and optimization could result in a reduced cost of production. Design specifications for the brushless DC motor were established based on the principle that the motor should be easy to construct with readily available parts, and should provide qualitative performance similar to many commercially available DC motors, such as those used in small electric fans. The motor was designed as a 3-phase, 4-pole brushless DC motor with 4 – N52 neodymium magnets on the rotor, and 3 wire wrapped solenoids connected to the stator. The brushless design was chosen because of the increased efficiency, reduced number of mechanical parts, and lower friction.
The N52 magnets were chosen for their strength, price, and easy availability. The solenoids are powered at 8-12 volts and controlled by an electrical switching circuit. 3 hall effect sensors will provide location information telling the circuit when to perform commutation. The following equations were used to estimate the performance of the motor and therefore create the initial motor design. These equations are messed up if you want to see them take a look at the pdf linked in the intro.
B is the magnetic field density at the surface of the magnet, A is the area of the magnet, and g is the distance between the two magnets. I is the current, N is the number of wraps, and l is the length of the solenoid. Combining these equations a linear expression relating the output torque to the input current can be obtained for a given solenoid geometry. A based on the desired performance relative to other available motors . BLDC motor control requires an electronic control circuit. To rotate the BLDC motor, the windings must be energized in a defined sequence depending on the position of the rotor.