4x L6234PD with STM32F401

[Paulo971]

Hello ST expert,

I'd like to control 4 300W motors with the BLDC L6234 and my STM32F401, but the problem is that I can't use 12 TIMERS and 12 GPIOs just for that, I need to interface other modules.

Can I just use PWM/BLDC, and interface the two like that?

STM32F401              L6234PD
|                      |
| PA6 (PWM) ----------> | EN1 (3)
| PA6 (PWM) ----------> | EN2 (6)
| PA6 (PWM) ----------> | EN3 (11)
| PB0 ----------------> | IN1 (17)
| PB1 ----------------> | IN2 (18)
| PB2 ----------------> | IN3 (19)
|                      |
|                      |                      
| 11V ----------------| VS (10)              |
| GND  ---------------| GND (1, 2, 7, 16) ----+
|                      |
|                      | OUT1 (4, 5) -------> Phase U of Motor
|                      | OUT2 (8, 9) -------> Phase V of Motor
|                      | OUT3 (14, 15) -----> Phase W of Motor

Best regard.

[cedric H]

Hello @Paulo971,

The In1, In2, In3 pins must be connected to three different channels (CH1, CH2, CH3) of the same Timer.

The EN1, EN2, EN3, must be connected to three different GPIOs.

These conditions are mandatory to properly control your motor with 6-STEP algorithm and proper BEMF detection.

I do not see how you could avoid multiplying these numbers by the number of motors, knowing that all those signals must be controlled independently. 

Do not hesitate to have a look at the schematic of the board STEVAL-IHM043V1 using this driver available here:

STEVAL-IHM043V1 - 6-Step BLDC sensorless driver board based on the STM32F051 and L6234 - STMicroelectronics

Regards

Cedric

[Paulo971]

Ok i understand, but what if i dont want to use the 6-step algorithme ? 

[cedric H]

Hum, but what kind of control do you want to achieve with your 300W motor?

If your idea is to apply to the four motors exactly the same duty cycle, then you will drive them in open loop with a very bad efficiency and without any way to maintain a torque or a speed. It is clearly a direction we do not encourage.

Regards

Cedric

[Paulo971]

The idea is to design a PCB that can independently control 4 three-phase motors for an omnidirectional RC car.

[cedric H · Accepted solution]

Hi @Paulo971 ,

From my point of view, you have no other choice than using 6 dedicated pins per motor.

Regards

Cedric