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How to convert s16A current measurements to Nm. Which current value should i consider and how do i convert it.

NP
Associate II
 
1 ACCEPTED SOLUTION

Accepted Solutions
Cristiana SCARAMEL
ST Employee

Hello @NP​,

the torque-current relationship of a motor is defined by the motor Torque Constant (Kt).

Kt = T (torque) / I (armature current) [Nm/A]

I hope this post can help you; if so, consider to mark it as best answer by clicking the label "Select as Best".

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3 REPLIES 3
Cristiana SCARAMEL
ST Employee

Hello @NP​,

the torque-current relationship of a motor is defined by the motor Torque Constant (Kt).

Kt = T (torque) / I (armature current) [Nm/A]

I hope this post can help you; if so, consider to mark it as best answer by clicking the label "Select as Best".

Hi Cristiana, does it represent that the STMotor Pilot read Torque value (unit s16A), equal to current (A) * 65536?

As in the source code mentioned:

/* Set the backup value of hTargetFinal. */

      wCurrentReference = ((int32_t)pHandle->TargetFinal) * 65536;

LSong.11
Associate II

@Cristiana SCARAMEL 

On speed_torq_ctrl.c there's an explanation STC_ExecRamp(), 

Current(digit) = [Current(Amp) * 65536 * Rshunt * Aop]  /  Vdd micro

looks like Current(digit) is 16 bit, shall s16A change to Volt(digit)? 

Could you help advise? Thanks.