TMS320F28388D: Motor reverse rotation

What control algorithm are you using? Sensoed or sensorless? FOC or trapezoidal?

Make sure that the initial position is detected for startup if you are using sensor based solution. Please provide more information of your questions. It's too simply to understand and answer.

Hi Luo, sorry for the insufficient information. Here are the details.

Control type

Sensored FOC (current control in d/q with SVGEN, using TI MotorControl SDK "Dual-Axis Mor Control Using FCL" example as baseline).

Position feedback: Incremental encoder attached to a motor via QEP

Startup / initial position handling

I’m using the SDK state machine: ENC_ALIGNMENT → ENC_WAIT_FOR_INDEX → ENC_CALIBRATION_DONE.

During ENC_ALIGNMENT, I apply Id current (IdRef_start) and set Iq = 0 to align the rotor.

After alignment, I go to ENC_WAIT_FOR_INDEX and rotate slowly to find the QEP index pulse.

When index is found, I move to ENC_CALIBRATION_DONE and then do the torque control.

Issue / symptoms

Sometimes the motor runs in the opposite direction of the torque command (IqRef).

I had suspected the rotor may not fully aligned/locked because I have some load on the motor, so I had increased IdRef_Start (0.05 to 0.22pu).

The frequency of this issue reduces but still it happens sometimes.

Could you advise me to get through this issue? Thank you for your support.

p.s. I am using a different motor, TEKNIC_3432PLN08D. The following is the motor parameter I calculated.

#define M1_RS          (0.273)                // Stator resistance (ohm)  0.546(p-p) / 2 = 0.273

#define M1_RR          (NULL)                // Rotor resistance (ohm)

#define M1_LS          (0.0006325)            // Stator inductance (H)    1.265 mH(p-p) / 1000 / 2 = 0.0006325

#define M1_LR          (NULL)                // Rotor inductance (H)

#define M1_LM          (NULL)                // Magnetizing inductance (H)

#define M1_FLUX        (0.1037358578)        // BEMF constant (V/Hz)    29.22 * 0.06 / 4 / sqrt(3) = 0.253052622985 -> (x * BASE_FREQ) / BASE_VOLT =  0.1037358578

#define M1_POLES      (8)                  // Number of poles

#define M1_ENCODER_LINES  (2000)                // Number of slots in the encoder    8000(quad-counts per rev) / 4(quad-encoder) = 2000

#define M1_BASE_FREQ    (66)            // About 1000 RPM

#define M1_BASE_VOLTAGE    (173.2)    //VDC 300 / sqrt(3)