...

Depending on the cost and performance of the board, it may be integrated elsewhere. Design target Target design parameters are also being pulled from Houston spec in Houston: Configuration.

Electrical Designer: Kenny Na (WARG EE F24 Co-op)

Project Manager: Daniel Puratich

Requirements

• Powered by a 3S (12V) battery input.

  • In the context of integrating with the ELRS board, an XT60 connector should be provided, and additional PWM input from a header pin should be placed (unsure of this requirement given we want to use DSHOT)for speed control.

  • 3x solder pads for BLDC connection.

  • Supports DSHOT input.

    • More resistant to noise in transmission versus PWM, as DSHOT is a digital protocol.

    • 12-5V Buck + ELRS was designed with PWM in mind but this can be altered.

  • An “OPTO” ESC, meaning no BEC is included.

• Must use the AM32 open-source firmware for motor control. (https://am32.ca)

  • This uses a sinusoidal algorithm to control the BLDC. (no FOC)

  • Has a strict MCU compatibility list (we would preferably use a smaller ST chip)

  • Sensorless operation Operation using back EMF . No and possibly current sensing. Likely no Hall sensing or current sense.

• Designed around an target motor (in Houston): https://innov8tivedesigns.com/cobra-cm-2217-20-brushless-motor-kv-950.html

  • Standard 3-phase brushless DC motor with 12 stator windings and 14 exterior magnet poles, meaning 4 coil windings per phase. Designed for 3S/4S power source.

    • With a higher density of magnet poles in the rotor, smoother torque is able to be produced by the motor. The rotor being on the outside gives more torque as well.

  • Maximum continuous current of 20 Amps.

    • Maybe 25A or 30A maximum burst current.

    • Should be accounted for during FET selection.

...

FET Selection

Main things to keep in consideration are the 20A max continuous current requirement, and any peak/transient current draw requirements from the motor. The STSPIN32F0’s gate driver can do 600mA sink/source.