Brushless motor control with encoder

Posted on May 17, 2011 at 10:15

Hi,

if SCALAR CONTROL is used, you can decide whether control or not the motor currents. In first case you can directly have control on motor torque. For this, you need a shunt resistor for current reading/sensing.

If you want to control motor voltage (basically controlling the motor speed), you need a resistor as well, for monitoring and/or limiting the maximum motor currents.

In ST technical literature dedicated to motor control, these two methods are referred respectively as Current Mode and Voltage Mode.

In Field Oriented Control (FOC) the current sensing is needed as well, but with a different meaning compared to Scalar Control. In that case we speak about Torque Mode or Speed Mode control if one want to have the control on motor Torque or its Speed.

Best regards,

Tanio

Posted on May 17, 2011 at 10:15

Hi, I've to control a brushless motor with an 512-impulse-encoder. Do I still need a current sensing method (like single-shunt or 3-shunt) if I've an encoder? I've only to control the speed...

Thanx!