MCT8329EVM: Hard Jerk During Startup in Drone Application

Babji Bommana

Part Number: MCT8329EVM

Tool/software:

Hi,

I am using the MCT8329EVM for a drone application and have noticed a hard jerk during the initial startup. I attempted to fine-tune the startup settings, but I haven’t been able to achieve a smooth start.

I am attaching my .json configuration file for reference. Could someone review it and suggest optimal settings for a smoother startup?

Thanks in advance!

Best Regards,
Babji

{
  "signature": "oneui-register-data",
  "data": [
    [
      {
        "idx": 0,
        "id": "isd_config",
        "value": "0x77404C06"
      },
      {
        "idx": 1,
        "id": "motor_startup1",
        "value": "0x6810620E"
      },
      {
        "idx": 2,
        "id": "motor_startup2",
        "value": "0x33452200"
      },
      {
        "idx": 3,
        "id": "closed_loop1",
        "value": "0x32547200"
      },
      {
        "idx": 4,
        "id": "closed_loop2",
        "value": "0x0FA1A429"
      },
      {
        "idx": 5,
        "id": "closed_loop3",
        "value": "0x34C92001"
      },
      {
        "idx": 6,
        "id": "closed_loop4",
        "value": "0x001AC953"
      },
      {
        "idx": 7,
        "id": "const_speed",
        "value": "0x30010000"
      },
      {
        "idx": 8,
        "id": "const_pwr",
        "value": "0x1F400640"
      },
      {
        "idx": 9,
        "id": "150_deg_two_ph_profile",
        "value": "0x24DB7200"
      },
      {
        "idx": 10,
        "id": "150_deg_three_ph_profile",
        "value": "0x48DB6946"
      },
      {
        "idx": 11,
        "id": "ref_profiles1",
        "value": "0x032184A6"
      },
      {
        "idx": 12,
        "id": "ref_profiles2",
        "value": "0x34C80AFC"
      },
      {
        "idx": 13,
        "id": "ref_profiles3",
        "value": "0x4787D70C"
      },
      {
        "idx": 14,
        "id": "ref_profiles4",
        "value": "0x000C9932"
      },
      {
        "idx": 15,
        "id": "ref_profiles5",
        "value": "0x1F6BF200"
      },
      {
        "idx": 16,
        "id": "ref_profiles6",
        "value": "0x00708000"
      }
    ],
    [
      {
        "idx": 0,
        "id": "algo_ctrl1",
        "value": "0x00000000"
      },
      {
        "idx": 1,
        "id": "device_ctrl",
        "value": "0x00000000"
      }
    ],
    [
      {
        "idx": 0,
        "id": "ana_trim3",
        "value": "0x48004800"
      },
      {
        "idx": 1,
        "id": "ana_trim4",
        "value": "0x2200000000"
      },
      {
        "idx": 2,
        "id": "ana_trim5",
        "value": "0x00000022"
      },
      {
        "idx": 3,
        "id": "ana_trim6",
        "value": "0x00000000"
      },
      {
        "idx": 4,
        "id": "ana_trim7",
        "value": "0x00000000"
      },
      {
        "idx": 5,
        "id": "ana_trim8",
        "value": "0x00001911"
      },
      {
        "idx": 6,
        "id": "ana_trim9",
        "value": "0x0085E7DA"
      },
      {
        "idx": 7,
        "id": "ana_trim10",
        "value": "0x537AF03D"
      }
    ],
    [
      {
        "idx": 0,
        "id": "fault_config1",
        "value": "0x71183604"
      },
      {
        "idx": 1,
        "id": "fault_config2",
        "value": "0x0540000B"
      }
    ],
    [
      {
        "idx": 0,
        "id": "gate_driver_fault_status",
        "value": "0x00000000"
      },
      {
        "idx": 1,
        "id": "controller_fault_status",
        "value": "0x00000000"
      }
    ],
    [
      {
        "idx": 0,
        "id": "gd_config1",
        "value": "0x000000FC"
      },
      {
        "idx": 1,
        "id": "gd_config2",
        "value": "0x00000000"
      }
    ],
    [
      {
        "idx": 0,
        "id": "pin_config1",
        "value": "0x20600002"
      },
      {
        "idx": 1,
        "id": "pin_config2",
        "value": "0x3E0020AA"
      },
      {
        "idx": 2,
        "id": "device_config",
        "value": "0x27104003"
      }
    ],
    [
      {
        "idx": 0,
        "id": "sys_status1",
        "value": "0x00A20000"
      },
      {
        "idx": 1,
        "id": "sys_status2",
        "value": "0x60010000"
      },
      {
        "idx": 2,
        "id": "sys_status3",
        "value": "0x00000000"
      }
    ]
  ]
}

6 months ago

0 Sachin S 6 months ago

TI__Expert 6011 points

Hello Babji,

I will review the .json file. Could you please try the settings in the following .json file and let me know if the issue is resolved. You may need to update the current level settings according to your application.

Fullscreen regs_drone.json Download

{
  "signature": "oneui-register-data",
  "data": [
    [
      {
        "idx": 0,
        "id": "isd_config",
        "value": "0x7FA06D3C"
      },
      {
        "idx": 1,
        "id": "motor_startup1",
        "value": "0x5B2A6369"
      },
      {
        "idx": 2,
        "id": "motor_startup2",
        "value": "0x35C20E87"
      },
      {
        "idx": 3,
        "id": "closed_loop1",
        "value": "0x0F45EA00"
      },
      {
        "idx": 4,
        "id": "closed_loop2",
        "value": "0x03AA493C"
      },
      {
        "idx": 5,
        "id": "closed_loop3",
        "value": "0x34C92400"
      },
      {
        "idx": 6,
        "id": "closed_loop4",
        "value": "0x001AC853"
      },
      {
        "idx": 7,
        "id": "const_speed",
        "value": "0x30010000"
      },
      {
        "idx": 8,
        "id": "const_pwr",
        "value": "0x0FA00640"
      },
      {
        "idx": 9,
        "id": "150_deg_two_ph_profile",
        "value": "0x24DB7200"
      },
      {
        "idx": 10,
        "id": "150_deg_three_ph_profile",
        "value": "0x48DB6946"
      },
      {
        "idx": 11,
        "id": "ref_profiles1",
        "value": "0x032184A6"
      },
      {
        "idx": 12,
        "id": "ref_profiles2",
        "value": "0x34C80AFC"
      },
      {
        "idx": 13,
        "id": "ref_profiles3",
        "value": "0x4787D70C"
      },
      {
        "idx": 14,
        "id": "ref_profiles4",
        "value": "0x000C9932"
      },
      {
        "idx": 15,
        "id": "ref_profiles5",
        "value": "0x1F6BF200"
      },
      {
        "idx": 16,
        "id": "ref_profiles6",
        "value": "0x00708000"
      }
    ],
    [
      {
        "idx": 0,
        "id": "algo_ctrl1",
        "value": "0x00000000"
      },
      {
        "idx": 1,
        "id": "device_ctrl",
        "value": "0x00008000"
      }
    ],
    [
      {
        "idx": 0,
        "id": "ana_trim3",
        "value": "0x48004800"
      },
      {
        "idx": 1,
        "id": "ana_trim4",
        "value": "0x2F00000000"
      },
      {
        "idx": 2,
        "id": "ana_trim5",
        "value": "0x0000002F"
      },
      {
        "idx": 3,
        "id": "ana_trim6",
        "value": "0x00000000"
      },
      {
        "idx": 4,
        "id": "ana_trim7",
        "value": "0x00000000"
      },
      {
        "idx": 5,
        "id": "ana_trim8",
        "value": "0x000048A2"
      },
      {
        "idx": 6,
        "id": "ana_trim9",
        "value": "0x00A9E7DD"
      },
      {
        "idx": 7,
        "id": "ana_trim10",
        "value": "0x5374F03B"
      }
    ],
    [
      {
        "idx": 0,
        "id": "fault_config1",
        "value": "0x71783604"
      },
      {
        "idx": 1,
        "id": "fault_config2",
        "value": "0x7EE5380A"
      }
    ],
    [
      {
        "idx": 0,
        "id": "gate_driver_fault_status",
        "value": "0x00000000"
      },
      {
        "idx": 1,
        "id": "controller_fault_status",
        "value": "0x00000000"
      }
    ],
    [
      {
        "idx": 0,
        "id": "gd_config1",
        "value": "0x000600FD"
      },
      {
        "idx": 1,
        "id": "gd_config2",
        "value": "0x00000000"
      }
    ],
    [
      {
        "idx": 0,
        "id": "pin_config1",
        "value": "0x00000002"
      },
      {
        "idx": 1,
        "id": "pin_config2",
        "value": "0x3E0020AE"
      },
      {
        "idx": 2,
        "id": "device_config",
        "value": "0x27100001"
      }
    ],
    [
      {
        "idx": 0,
        "id": "sys_status1",
        "value": "0x00D00000"
      },
      {
        "idx": 1,
        "id": "sys_status2",
        "value": "0x60010000"
      },
      {
        "idx": 2,
        "id": "sys_status3",
        "value": "0x00000000"
      }
    ]
  ]
}

Thanks and regards,

Sachin S

0 Babji Bommana 6 months ago in reply to Sachin S

Prodigy 100 points

Hi Sachin,

We went through the JSON file and made some changes to the system-level configuration, specifically COMM_CONTROL and PWM_FREQ_OUT. These adjustments significantly improved the startup smoothness.

We tested the setup around 5 to 10 times while increasing the speed. However, at random instances, we encountered a Loss of Sync Fault. To address this, we tried several additional changes, but the issue persisted. Eventually, we attempted to disable the Loss of Sync Fault, but it still kept appearing.

For our use case, it is acceptable to have Loss of Sync Fault disabled, but we are unable to fully suppress it. Any insights on how to resolve this?

Thanks and regards,
Babji

0 Sachin S 6 months ago in reply to Babji Bommana

TI__Expert 6011 points

Hello Babji,

Could you share some waveforms of the output phase current? Want to understand what is exactly causing the LOSS_OF_SYNC. Also, what is the acceleration rate you are targeting?

Thanks and regards,

Sachin S

0 Babji Bommana 6 months ago in reply to Sachin S

Prodigy 100 points

Hello Sachin,

Could you help me understand how to check the output phase current on the MCT8329EVM? Also, our acceleration rate is around 2–3 ms, which is what we are expecting. What would be the best approach for measuring or monitoring the phase current waveform?

Thanks and regards,
Babji

0 Sachin S 6 months ago in reply to Babji Bommana

TI__Expert 6011 points

Hello Babji,

Babji Bommana said:
Could you help me understand how to check the output phase current on the MCT8329EVM

If you have an oscilloscope and a current probe, you can probe the current through one of the phase windings (one of the three wires connecting the motor to the EVM).

Babji Bommana said:
Also, our acceleration rate is around 2–3 ms, which is what we are expecting

Could you let me know what is the maximum speed you are targeting to reach within 2-3ms?

Thanks and regards,

Sachin S

0 Babji Bommana 5 months ago in reply to Sachin S

Prodigy 100 points

Hi Sachin,

We currently don’t have current probes, but we do have a differential probe. What would you suggest in this case? If needed, we can provide voltage measurements for all three phases.

We have attached the waveform using voltage for reference.

Regarding acceleration, for initial startup, a lower acceleration rate is acceptable. However, after startup, we require a faster response rate for varying speed, as our application is for a drone. Do you have any recommendations on optimizing this behavior?

Thanks and regards,
Babji

0 Sachin S 5 months ago in reply to Babji Bommana

TI__Expert 6011 points

Hi Babji,

Thanks for the details. You can keep closed loop accelerations high and also increase the speed loop kp and ki to achieve a faster response for varying speed.

Regards,

Sachin S

0 Babji Bommana 5 months ago in reply to Sachin S

Prodigy 100 points

Hi Sachin,

We have already set the closed-loop acceleration rates high (60V/s and 125V/s). Our main goal is to smoothen the startup while ensuring there are no Loss of Sync errors.

Thanks & Regards,

Babji

0 Sachin S 5 months ago in reply to Babji Bommana

TI__Expert 6011 points

Hi Babji,

Could you try setting CLOSED_LOOP_MODE to Speed Mode and try tuning the SPD_LOOP_KP and SPD_LOOP_KI

Thanks and regards,

Sachin S

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MCT8329EVM: Hard Jerk During Startup in Drone Application