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CCS/DRV8305: wrong handover for Ls and Rs values

Prodigy 110 points

Replies: 5

Views: 116

Part Number: DRV8305

Tool/software: Code Composer Studio

Hi!

I started to become familiar with an existing Firmware for a custom designed Motor driver (F28069M+DRV8305). Basicly the system works but I think there are a lot improvements possible.

First I started to check all user parameters. Thereby I found some wrong values. (But this is not part of my question ;) )

During debugging I saw that Ls an Rs have strange values:

The values are much higher than in the user.h file. Looks like an overflow?!

Furthermore I have following warning:

Can this be the problem? This is my struct:

typedef struct _MOTOR_Vars_t_
{
  bool Flag_enableSys;
  bool Flag_Run_Identify;
  bool Flag_MotorIdentified;
  bool Flag_MotorAligned;
  bool Flag_enableForceAngle;
  bool Flag_enableFieldWeakening;
  bool Flag_enableRsRecalc;
  bool Flag_enableUserParams;
  bool Flag_enableOffsetcalc;
  bool Flag_enablePowerWarp;

  unsigned int MotorAlign_Rampup_Ticks;
  unsigned long MotorAlign_Ticks;

  CTRL_State_e CtrlState;
  EST_State_e EstState;

  USER_ErrorCode_e UserErrorCode;

  CTRL_Version CtrlVersion;

  _iq IdRef_A;
  _iq IqRef_A;
  _iq StopSpeedRef_krpm;
  _iq SpeedRef_krpm;
  _iq SpeedTraj_krpm;
  _iq MaxAccel_krpmps;
  _iq MaxAccel_index_krpmps;
  _iq20 MaxJrk_krpmps2;
  _iq Speed_krpm;
  _iq SpeedQEP_krpm;
  _iq OverModulation;
  _iq RsOnLineCurrent_A;
  _iq SvgenMaxModulation_ticks;
  _iq Flux_Wb;
  _iq Torque_Nm;
  _iq I_Max_A;

    float_t MagnCurr_A;
  float_t Rr_Ohm;
  float_t Rs_Ohm;
  float_t RsOnLine_Ohm;
  float_t Lsd_H;
  float_t Lsq_H;
  float_t Flux_VpHz;

  _iq Kp_spd;
  _iq Ki_spd;

  _iq Kp_Idq;
  _iq Ki_Idq;

  _iq Vd;
  _iq Vq;
  _iq Vs;
  _iq VsRef;
  _iq VdcBus_kV;

  _iq Id_A;
  _iq Iq_A;
  _iq Is_A;

  MATH_vec3 I_bias;
  MATH_vec3 V_bias;

  ST_Vars_t SpinTAC;

  //float Axis_Offset_Ang;

}MOTOR_Vars_t;

With my eval-Kit and lab03a everthing looks fine. On our custom board we  use the FPU.  Maybe is there the source of the problem?

Thanks!

  • 1. It seems like you or your customer had changed the example code, please check and change the "MOTOR_Vars_INIT" accordingly if you added any variable in MOTOR_Vars_t struct.

    2. Make sure the current & voltage sensing signals are good for motor control.

    3. Set the appropriate identification variables (USER_MOTOR_RES_EST_CURRENT, USER_MOTOR_IND_EST_CURRENT, USER_MOTOR_MAX_CURRENT,  USER_MOTOR_FLUX_EST_FREQ_Hz) according to the motor specification.

     

  • In reply to Yanming Luo:

    Thanks!

    1.  My fault was that I defined the  _iq MaxAccel_krpmps value higher than 127 (IQ24)

    2. Do you mean to run lab1b and lab1c or to check the signal at my hardware?. I´m a beginner in this subject.

    3. I will try this.  If i set the Flag  "Flag_enableRsRecalc"  to 1  is only Rs new calculated or both? Rs und Ls


  • In reply to Yanming Luo:

    After I set gMotorVars.Flag_Run_Identify to 1 the values Ls and Rs change immediately to this values. When I change the values im my user.h file the wrong values also change ?!

  • In reply to Yanming Luo:

    One more question:

    When I use the FPU I get an int32 value:

    //! \brief     Gets the stator resistance value in Ohms (\f$\Omega\f$).
    //! \param[in] handle  The estimator (EST) handle
    //! \return    The stator resistance value, Ohm
    #ifdef __TMS320C28XX_FPU32__
    extern int32_t EST_getRs_Ohm(EST_Handle handle);
    #else
    extern float_t EST_getRs_Ohm(EST_Handle handle);
    #endif

    Inside th struct they are defined as float_t

     float_t MagnCurr_A;
      float_t Rr_Ohm;
      float_t Rs_Ohm;
      float_t RsOnLine_Ohm;
      float_t Lsd_H;
      float_t Lsq_H;
      float_t Flux_VpHz;

    I tried following things:

    //   get the stator resistance
    //  gMotorVars.Rs_Ohm=EST_getRs_Ohm(obj->estHandle);
      tmp = EST_getRs_Ohm(obj->estHandle);
      gMotorVars.Rs_Ohm = *((float_t *)&tmp);

    result: no errors, but program doesn´t work. Program get stuck  at some point.

    The same thing happens when I comment the whole line

    //  gMotorVars.Rs_Ohm=EST_getRs_Ohm(obj->estHandle);


    My questions:
    1. Is the reason that the motor works because "inside" InstaSpin the values for Rs an Ls are correct and only the handover to the gMotorVars.Rs value is wrong?
    2. Why I can´t comment a get-line inside void updateGlobalVariables_motor(CTRL_Handle handle)
    3. I read in another thread that all gMotorValues are read only. Is this correct?
    4. What can I do that I have the rigth values for Rs an Ls in my expressions?

    Thanks!

  • In reply to BB01:

    Can you take a look at the InstaSPIN lab guide that includes the answer to all the questions you asked above? The guide can be found in the folder of the motorWare as below. You'd better run these labs one by one and use the TI EVM kit if possible before you are familiar with these labs.

    \ti\motorware\motorware_1_01_00_18\docs\labs

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