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INSTASPIN-BLDC: low inductance induction motor

Hideya Matsunaga
Prodigy 40 points
Part Number: INSTASPIN-BLDC
Other Parts Discussed in Thread: LAUNCHXL-F28069M

I want to drive a low inductance induction motor with my own board.
Controler is LAUNCHXL-F28069M with instaspin Labs.
The motor is a 3-phase induction motor used in vehicles (86V,350A).
And Inverter is IGBT.(up to 20kHz PWM)


[problem]
USER_checkForErrors() output following errors.
・USER_ErrorCode_iqFullScaleVoltage_V_High
・USER_ErrorCode_iqFullScaleVoltage_V_Low

Simple solution is increase PWM frequency(Example 30kHz).
But this IGBT is up to 20kHz and processing is not in time.
Another solution is  decrease IQ voltage or IQ current,
but that will reduce the power...

any another solutions？


[setting]
USER_IQ_FULL_SCALE_FREQ_Hz   (800.0)
USER_IQ_FULL_SCALE_VOLTAGE_V (100.0)
USER_IQ_FULL_SCALE_CURRENT_A (500.0)
USER_PWM_FREQ_kHz_M1         (16.0)

USER_NUM_PWM_TICKS_PER_ISR_TICK        (1)
USER_NUM_ISR_TICKS_PER_CTRL_TICK       (1)
USER_NUM_CTRL_TICKS_PER_CURRENT_TICK   (1)
USER_NUM_CTRL_TICKS_PER_EST_TICK       (1)

USER_VOLTAGE_FILTER_POLE_Hz           (300.0)

USER_MOTOR_TYPE                 MOTOR_Type_Induction
USER_MOTOR_NUM_POLE_PAIRS       (4)
USER_MOTOR_Rr                   (0.018)
USER_MOTOR_Rs                   (0.0247)
USER_MOTOR_Ls_d                 (0.0000656)
USER_MOTOR_Ls_q                 (USER_MOTOR_Ls_d)
USER_MOTOR_RATED_FLUX           (0.06946983)
USER_MOTOR_MAGNETIZING_CURRENT  (14.0)
USER_MOTOR_MAX_CURRENT          (400.0)

  • 0
    TI__Guru** 114310 points
    It seems like the USER_MOTOR_RATED_FLUX is not right for this board or motor. You need to run the lab02b or lab02c first to identify the motor parameters, and must the USER_MOTOR_RATED_FLUX in user.h first with the formula (sqrt(2/3)* Rated V (line-line) / Rated Freq (Hz)) since the motor is an ACIM.
  • 0 in reply to Yanming Luo
    Prodigy 40 points
    I see.
    But, I identified motor parameters by lab02c.
    the result, USER_MOTOR_RATED_FLUX = 0.069 V/H.
    Does the identify result depend on the DC voltage?　(The motor rating is 86V , I tried 36V.)

    By the way, there is no rating frequency for this motor. (Special motor for vehicle. )
    How to set the initial value of RATED_FLUX [V / H] in this case?
    If set the approximate value, will it be adjusted by estimation?
  • 0 in reply to Hideya Matsunaga
    TI__Guru** 114310 points
    1. As replied to you above, for ACIM, the USER_MOTOR_RATED_FLUX must be set an initial value based on the specification of the motor using the formula "sqrt(2/3)* Rated line-line voltage (V)/ Rated Freq (Hz)". The value is not dependent on the DC voltage.
    2. The USER_MOTOR_FLUX_EST_FREQ_Hz must be set to 5Hz for most ACIM.
    3. For such low inductance motor, a higher PWM frequency is a better choice for instaSPIN-FOC, if the inverter can't support, you have to re-design the h/w and improve the PWM frequency.