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[Question] BLDC motor torque and speed control with L6235 / L6229

Question asked by Oblique on Oct 20, 2013

I would like to ask to the experts a question regarding BLDC motor control.
I am currently trying to develop a Brushless motor controller that allows me to control the torque and speed of the motor. The motor is very small, has 3 phases, 3 hall sensors and weights 7 grams. The model is a Faulhaber 1509 006B.

I have an ST DMOS driver chip, model L6235 in DIP so I can do some testing on a bread board before designing a PCB. This chip seems a very good solution for my problem, since it has power drivers, hall sensor and commutation logic integrated, however I'm finding hard to understand if it allows torque control (for speed control is clear that is possible according to the datasheet and application note AN1625). I intend to interface it with a microcontroller and have a I2C communication, where I send speed and torque commands and receive the respective values.

If I interface this DMOS driver with a microcontroller, can I control the torque the same way speed is controlled as suggested in the Design Tip DT0001 or in any other way?
The torque ripple is an important issue for the end application of this controller so I need to minimize this parameter as much as possible.
Probably I will also change to the model L6229 since I will use a micro BLDC motor and L6235 seems way too much for what I need and L6229 has a smaller package for the final design.

I would appreciate if someone could provide some insight over this problem.