3 phase BLDC motor driver.

Thanks to Avi (arots) for the code for this!

This is a 3 phase oscillator based on an STM32. The uC takes a clock input, and outputs 3 square waves 120 degrees out of phase from on another. The clock input was an inverter oscillator with a 74hc14. I used a 10 turn precision pot to change the frequency.

The motor in this video was a small motor from a CD rom (hence the CD fitting on top so well). At a certain point, the motor because unbalanced and vibrates like hell, which makes the motor 'slip' and lose synchronization and stop.

The output of the oscillator went through a resistive divider (works fine at this frequency) for about 2v clock. The outputs of the STM32 went to the 74hc14 for buffering, which drives 3 totem poles of darlington NPN and PNP transistors. The transistors had 5v input. The transistors where bdw93cfp and bdw94cfp (9 amp 100v).

Category:

Science & Technology

Tags:

• STM32
• micro
• controller
• BLDC
• brushless
• DC
• phase
• motor
• programming

[petoknm]

if the motor has hall sensors...you could set interupts for the MCU...it would be much easier to drive...but code will be a bit more complex...xD but great driver...which MCU are u using here?

[triggerhappy77707]

@petoknm Yea, and it would only require some buffers to use the hall sensors instead of an entire uC :P. This is an stm32f103. 512kb of flash memory... Not bad for 25 USD.

[ubuntupokemoninc]

schema?

[triggerhappy77707]

@ubuntupokemoninc It uses an entire uC, so i dont have a schematic. The hex inverter uses a cap and resistor, google inverter oscillator. The 3 phase bridge is simple, just 3 totem poles made from transistors, that can be googled too.

[khoham]

so you made this brushless motor out of a cd motor.. not bad these always make great 3 phase motors.. You should try doing it without the uC.. I'ld say it could be done creating an astable multivibrator and creating the third phase with capacitors.. I could vouch that this also controls power factor reducing power draw.. you could control the frequency by changing the capacitance at the vibrator