TMS320F280025C: induction motor

Hi,

Our expert is out of office until early January, please expect a delayed response.

Best Regards,

Ben Collier

hello Jason,

Thank you for your reply, in some TI documents it is mentioned that for Motor parameter estimation of ACIM rotor must be locked. Is it the case in universal motor control lab.

Regards

Prashanth

Hello Jason,

We tried estimating Induction motor parameters, but estimation stops at EST_STATE_LC and motor is turned off. Our motor is ACIM with rated voltage of 230V and rated current of 9A.

We are using following parameters.

#define USER_MOTOR1_TYPE MOTOR_TYPE_INDUCTION
#define USER_MOTOR1_NUM_POLE_PAIRS (2)
#define USER_MOTOR1_Rr_Ohm (NULL)
#define USER_MOTOR1_Rs_Ohm (NULL)
#define USER_MOTOR1_Ls_d_H (NULL)
#define USER_MOTOR1_Ls_q_H (NULL)
#define USER_MOTOR1_RATED_FLUX_VpHz (0.8165*230.0/50.0)
#define USER_MOTOR1_MAGNETIZING_CURRENT_A (NULL)
#define USER_MOTOR1_RES_EST_CURRENT_A (3.0f)
#define USER_MOTOR1_IND_EST_CURRENT_A (-1.0f) 
#define USER_MOTOR1_MAX_CURRENT_A (11.0)
#define USER_MOTOR1_FLUX_EXC_FREQ_Hz (5.0f)

can you help us in identifying the issue. Thanks in advance.

Regards

Prashanth

Prashanth,

• What faults are present after the motor stops, if any? What state is the motor state machine in? Also, was there any visible destabilization in the motor rotation or motor current waveform? Without that information, it is difficult for me to know what happened.
• If the motor is a very low inductance motor, then FLUX_EXC_FREQ_Hz will need to be increased somewhat.
• Consider section 6.7 'Full Identification of ACIM Motors 'of the InstaSPIN-FOC and InstaSPIN-MOTION User's Guide.
  • Specifically, I would note the advice to adjust IDRATED_DELTA if the phase current magnitude is visibly oscillating (see figure 6-32)

Regards,
Jason Osborn

Hello Jason,

I am our current wave forms, the wave form was not steady at 5Hz, but at 20Hz the current signal is steady. 

Initial USER_MOTOR1_RATED_FLUX_VpHz (0.8165*230.0/50.0) = 3.75 value is set and similar value is visible in debug window during open loop estimation and same is replaced by estimated value after EST_STATE_RATEDFLUX sate and the current in this state is half that of EST_STATE_IDRATED.

After this state motor is turing off at EST_STATE_LOCKROTOR. at follwing code in motor1_drive.c. Is there issue with bypass locked rotor.

In the debug window the state is displayed as EST_STATE_LS after motor turn off.

if(objUser->flag_bypassMotorId == false)
{
if((EST_isLockRotor(obj->estHandle) == true) ||
( (EST_isMotorIdentified(obj->estHandle) == true)
&& (EST_isIdle(obj->estHandle) == true) ) )
{
if(EST_isMotorIdentified(obj->estHandle) == true)
{
obj->flagMotorIdentified = true;

// clear the flag
obj->flagRunIdentAndOnLine = false;
obj->flagEnableRunAndIdentify = false;

// disable the estimator
EST_disable(obj->estHandle);

// enable the trajectory generator
EST_disableTraj(obj->estHandle);
}

if(objUser->motor_type == MOTOR_TYPE_INDUCTION)
{
// clear the flag
obj->flagRunIdentAndOnLine = false;
obj->flagEnableRunAndIdentify = false;
}
}
} // objUser->flag_bypassMotorId = false

Full  screent shot

Ramp up

EST_STATE_IDRATED

EST_STATE_RATEDFLUX

Regards

prashanth

Hello Jason,

Thank you for your reply. our wave form is similir till EST_STATE_RAMPDOWN after that motor is disabled.

Jason Osborn said:

To be clear, the motor is not supposed to move during the Locked Rotor state

The program is not wiating in locked rotor state it is quickly changing to EST_STATE_LS and switching off. do we have increase wait times. the wait times are set to zero for ramp down and locked rotor state. 

As per your earlier comment

Jason Osborn said:

If I recall correctly, the InstaSPIN-FOC FAST library takes care of that internally

we can avoid locking rotor.

follwing fault flag are set

Phase imbalance, over frequency and startup fail and these are set before rampup state. 

The wait times should not be set to 0. Refer to the guide I provided before on the correct values which should be assigned.

Regards,
Jason Osborn

Hello Jason,

After adding wait time in EST_STATE_RAMPDOWN and EST_STATE_LOCK. The controller is waiting at lock rotor and getting disabled. After re enabling controller, it is proceeding to EST_STATE_LS and EST_STATE_RR after that we are getting EST_STATE_MOTORIDENTIFIED.

But during EST_STATE_LS the wave form is as follows it is not running for full wait time set 

objUser->LsWaitTime[EST_LS_STATE_ERROR] = 0;
objUser->LsWaitTime[EST_LS_STATE_IDLE] = 0;
objUser->LsWaitTime[EST_LS_STATE_RAMPUP] = (int_least32_t)(10.0 * USER_M1_ISR_FREQ_Hz);
objUser->LsWaitTime[EST_LS_STATE_COARSE] = (int_least32_t)(30.0 * USER_M1_ISR_FREQ_Hz);
objUser->LsWaitTime[EST_LS_STATE_FINE] = (int_least32_t)(30.0 * USER_M1_ISR_FREQ_Hz);
objUser->LsWaitTime[EST_LS_STATE_DONE] = 0;

and motor is not spinning during estimation. The current is set to -2.0 and frequency is 1.5Hz.

If the motor is not spinning at all during any point in the estimation process, it is likely that the other issues you're facing are related to that.

Have you had a chance to read the InstaSPIN-FOC and InstaSPIN-MOTION User's Guide? Section 4.8.1.2 "Entering ACIM Motor Parameters from a Data Sheet to user.h" and Section 5 "Managing Motor Signals" seem like they may be particularly helpful. Typically, if the motor is not spinning, it's because a basic parameter needs correction.

Additionally, have you verified the voltage, current, and PWM signals on your custom board are all good quality?

Regards,
Jason Osborn

Hello Jason,

Yes, we referred to the user guide, our offset calibration for both current and voltage signals are not returning errors.

the motor is spinning during ramp up and flux estimation. But it is not spinning after re enabling the motor after LOCKED_ROTOR state.

We do not have detailed datasheet of motor giving motor resistance and inductance, so we are trying to estimate motor parameters.

the estimation frequency during LS is low less than 2HZ at the frequency motor will not spin. 

The same board is working fine with PMSM motor it is able estimate motor parameters and run in closed loop with estimated parameters. We verified with different PMSM mottors.

Regards

Prashanth

prashanth dodla said:

We are using following parameters.

#define USER_MOTOR1_TYPE MOTOR_TYPE_INDUCTION
#define USER_MOTOR1_NUM_POLE_PAIRS (2)
#define USER_MOTOR1_Rr_Ohm (NULL)
#define USER_MOTOR1_Rs_Ohm (NULL)
#define USER_MOTOR1_Ls_d_H (NULL)
#define USER_MOTOR1_Ls_q_H (NULL)
#define USER_MOTOR1_RATED_FLUX_VpHz (0.8165*230.0/50.0)
#define USER_MOTOR1_MAGNETIZING_CURRENT_A (NULL)
#define USER_MOTOR1_RES_EST_CURRENT_A (3.0f)
#define USER_MOTOR1_IND_EST_CURRENT_A (-1.0f) 
#define USER_MOTOR1_MAX_CURRENT_A (11.0)
#define USER_MOTOR1_FLUX_EXC_FREQ_Hz (5.0f)

The number of pole pairs might relate to stator tooth slots/2 if this is a typical non magnet induction motor there are 0 pole pairs. Instead, there are async electrical slip degrees AC induction motors. Perhaps ~EST_CURRENT_A(3.0f) is too low for a motor 9A peak? Perhaps why rotor may never really enter a locked state. You can test lock exists by using your fingers, when it enters lock state try to spin the rotor in either direction. If you can easily spin the rotor shaft, it perhaps is not truly in a locked state when LS tests induction.

You can also try reducing state times if LS returns bizarre values during motor identification. A custom PCB returned induction values often act differently than the booster pack DRV class of motor driver boards on TI launch pad. Perhaps try to identify the PMSM on your custom PCB to get an idea of these state times need be adjusted to return more realistic induction values. R/L state is another value that can produce incorrect resistance values. The motor control SDK state machine times may vary based on the CPU clock speed that you configured for x25c if set less than 100MHz. Check if your custom PCB current sensors are inverting the output, that is set (+/-) in user.h or user_motor1.h universal motor SDK.

objUser->LsWaitTime[EST_LS_STATE_RAMPUP] = (int_least32_t)(10.0 * USER_M1_ISR_FREQ_Hz);
objUser->LsWaitTime[EST_LS_STATE_COARSE] = (int_least32_t)(30.0 * USER_M1_ISR_FREQ_Hz);
objUser->LsWaitTime[EST_LS_STATE_FINE] = (int_least32_t)(30.0 * USER_M1_ISR_FREQ_Hz);

hello Genatco,

Sorry for delayed reply, In our custom board PMSM is running fine. The estimated vales are consistent across multiple trials. We tested with different PMSM motors ranging from 110V-6A to 480V 14A. All PMSM motor are working well. 

Do we have to adjust wait time for ACIM. Rs estimate returns similar values for multiple values. Shall we try with higher inductance estimate current as the motor is not spinning during LS estimation.

We are using inline hall current sensor without inversion.

Regards

prashanth

prashanth dodla said:

Shall we try with higher inductance estimate current as the motor is not spinning during LS estimation

Text states rotor remains locked during LS estimation. The lock state control is automatic for induction motors during motor ID process. After motor ID = true isLAB_05 should unlock rotor able to test run induction motor and copy CCS debug script values into user.h, induction motor parameters. 

Sometimes compiled bool flag states don't always behave in CCS debug, proactive use estimator ROM calls in motor state control functions. 

// Proper flag setting both motor types isLAB_05
    //
    // if motor is an induction motor, configure default state of PowerWarp
    //
    if(userParams.motor_type == MOTOR_TYPE_INDUCTION)
    {
        motorVars.flagEnablePowerWarp = true;
        EST_setFlag_enablePowerWarp(estHandle, motorVars.flagEnablePowerWarp);
        motorVars.flagBypassLockRotor = false;
        EST_setFlag_bypassLockRotor(estHandle, motorVars.flagBypassLockRotor);
    }
    else
    {
        motorVars.flagEnablePowerWarp = false;
        EST_setFlag_enablePowerWarp(estHandle, motorVars.flagEnablePowerWarp);
        motorVars.flagBypassLockRotor = true;
        EST_setFlag_bypassLockRotor(estHandle, motorVars.flagBypassLockRotor);
    }
           
           
           
           if( (EST_isLockRotor(estHandle) == true) ||
                     ((EST_isMotorIdentified(estHandle)
                       && EST_isIdle(estHandle)) == true))
                {
                    if(EST_isMotorIdentified(estHandle) == true)
                    {
                        motorVars.flagMotorIdentified = true;
                        //! \brief     Sets the motor identified flag state in the estimator
                        EST_setFlag_motorIdentified(estHandle, true);
                        //! \brief     Sets the bypass lock rotor flag value in the estimator
                        motorVars.flagBypassLockRotor = true;
                        EST_setFlag_bypassLockRotor(estHandle, motorVars.flagBypassLockRotor);
                        //
                        // set up the PI control according to the identification
                        // motor parameters
                        //
                        userParams.motor_ratedFlux_Wb = motorVars.flux_VpHz / MATH_TWO_PI;

                        userParams.motor_Rr_d_Ohm = motorVars.Rr_Ohm;
                        userParams.motor_Rr_q_Ohm = motorVars.Rr_Ohm;

                        userParams.motor_Rs_a_Ohm = motorVars.Rs_Ohm;
                        userParams.motor_Rs_b_Ohm = motorVars.Rs_Ohm;

                        userParams.motor_Rs_d_Ohm = motorVars.Rs_Ohm;
                        userParams.motor_Rs_q_Ohm = motorVars.Rs_Ohm;

                        userParams.motor_Ls_d_H = motorVars.Ls_d_H;
                        userParams.motor_Ls_q_H = motorVars.Ls_q_H;

                        CTRL_setParams(ctrlHandle, &userParams);

                    }