11 Replies Latest reply on Aug 28, 2018 2:52 AM by JobinT_31

    Motor control with Kit 037 fails at high speed


      I have been trying to use the Kit 037 to control a BLDC motor using FOC. The kit is working fine with the included motor, but when I try to make it work with my own motor (RoboDrive ILM 25x 04) it fails at high speed.

      As far as I know, only these parameters should be modified:

      int32_t   Motor_i32PolePairs      = 4;    // the pole pairs of rotor

      float32_t Motor_f32Ld             = 0.006;  // the d axis inductance  

      float32_t Motor_f32Lq             = 0.006; // the q axis inductance 

      float32_t Motor_f32Res            = 1.1;    // the resistance between two phases

      float32_t Motor_f32Ke             = 2.83;   // inductive voltage constant between two phases,RMS value


      I have observed that information in the datasheet does not match the values in the example project "Sensorless FOC Motor Control". The datasheet states that the line to line resistance is 0.8 ohm, while the value in the firmware is 1.1. Why is this?

      How is the "inductive voltage constant between two phases,RMS value" calculated?


      Also, how to obtain the other values (Ld, Lq and voltage constant)?

      I know that my motor has 7 pole pairs, 0.5ohm of terminal resistance, 170uH terminal inductance, 24V rated voltage and 24kRPM rated speed.


      Is there a document or something I can read to better understand the other parameters and the firmware algorithm? I would like to change the closed loop parameters too, but can't find what does everyone of them do in the algorithm.