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MCT8329EVM: EVM board current rating

Part Number: MCT8329EVM
Other Parts Discussed in Thread: MCT8329A,

Hi, what the output current rating of the MCT8329A EVM board?  The most I can get is about 8amps pk.

The cycle by cycle current limit setting in the GUI don't seem to have any effect.

The MOSFETs in the EVM board are rated ot 200A, but all I need is about 30A to start the motor.  

  • Can you go to File->Save registers and share the .json file? 

  • I have it, but i'm not sure how to send it.  I dragged and dropped in to this window. do you see "Ti chip register set that runs.json"? 

  • In this E2E forum, there is a Insert function but it only seem to be for images no files. 

    I increased all limits to their max, I have CSA_GAIN set to 5v/v,  CBC_ILIMIT set to 1.5v ,LOCK_ILIMIT set to 2.7v.  No change it motor current, it still trips at 8 amps. 

    According to the formula below, I should be getting 285 Amps!

    R sense in the EVM board appears to be 0.001ohm.

      

  • Phil,

    I don't see any files attached to your response. Do you see "Insert" option? Can you click this and click "Image/Video/File" and upload the json file? Did you read the fault status in GUI? Is there any fault that is getting triggered? 

    Regards,

    Vishnu

  • Here is the datasheet of MCT8329EVM Evaluation Module. It says ". The Gate Drive architecture supports peak gate drive currents up to 1-A source and 2-A sink."

    https://www.ti.com/lit/ug/sllu359a/sllu359a.pdf

    However, if you need a Powerful 30A DC Motor Driver using Power Mosfets, you can make this board.

    www.pcbway.com/.../A_Powerful_30A_DC_Motor_Driver_using_Power_Mosfets.html

  • Zain,

    MCT8329EVM has MOSFETs that can drive currents up to 300A so there shouldn't be any issue with the hardware. This could be a tuning issue. 

    Regards,

    Vishnu

  • Yes it's definitely a tuning issue.  I have increased both CBC_Limit and LOCK_ILIMIT to their maximums and I have CSA_GAIN set to 5v/v. Should be 280amp limit by the formula.  But no matter what I set them to, it always trips at 8 amps. 

    How can I see if the chip is even taking my changes? 

    I do have a current probe attached to my oscilloscope so I can see the peak current in real time.

  • Phil,

    After modifying the register values, can you click "Write to EEPROM" and power cycle the device and try again? Using the current probe, can you check if you see any current spikes on any of the motor phases?

    Also, can you try the attached JSON file? You can load this file by clicking File->Load register. Once you load it, click  "Write to EEPROM" and power cycle the device

    {
      "signature": "oneui-register-data",
      "data": [
        [
          {
            "idx": 0,
            "id": "isd_config",
            "value": "0x7F404D02"
          },
          {
            "idx": 1,
            "id": "motor_startup1",
            "value": "0x6C9265B7"
          },
          {
            "idx": 2,
            "id": "motor_startup2",
            "value": "0x332D3295"
          },
          {
            "idx": 3,
            "id": "closed_loop1",
            "value": "0x1025E600"
          },
          {
            "idx": 4,
            "id": "closed_loop2",
            "value": "0x02A1A428"
          },
          {
            "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": "0x00000000"
          },
          {
            "idx": 1,
            "id": "ana_trim4",
            "value": "0x00000000"
          },
          {
            "idx": 2,
            "id": "ana_trim5",
            "value": "0x00000000"
          },
          {
            "idx": 3,
            "id": "ana_trim6",
            "value": "0x00000000"
          },
          {
            "idx": 4,
            "id": "ana_trim7",
            "value": "0x00000000"
          },
          {
            "idx": 5,
            "id": "ana_trim8",
            "value": "0x00000000"
          },
          {
            "idx": 6,
            "id": "ana_trim9",
            "value": "0x00000000"
          },
          {
            "idx": 7,
            "id": "ana_trim10",
            "value": "0x00000000"
          }
        ],
        [
          {
            "idx": 0,
            "id": "fault_config1",
            "value": "0x71783604"
          },
          {
            "idx": 1,
            "id": "fault_config2",
            "value": "0x7C85C00A"
          }
        ],
        [
          {
            "idx": 0,
            "id": "gate_driver_fault_status",
            "value": "0x00000000"
          },
          {
            "idx": 1,
            "id": "controller_fault_status",
            "value": "0x00000000"
          }
        ],
        [
          {
            "idx": 0,
            "id": "gd_config1",
            "value": "0x000600FC"
          },
          {
            "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": "0x27100008"
          }
        ],
        [
          {
            "idx": 0,
            "id": "sys_status1",
            "value": "0x00000000"
          },
          {
            "idx": 1,
            "id": "sys_status2",
            "value": "0x00000000"
          },
          {
            "idx": 2,
            "id": "sys_status3",
            "value": "0x00000000"
          }
        ]
      ]
    }

    Regards,

    Vishnu

  • I was able to inject your file. Your fie achieved 12-14Amps at start up, but doesn't run, it fails to enter closed loop.

    My file runs and actually achieves more, 15-17amps at startup with CBC_Limit set to 1V but only 8-10amps if I load it while running. 

    I verified my parameter changes are going into the chip by doing write to EEPROM, then READ from EEPROM as you instructed.  

    If I change the CBC_Limit to 1.5 in my file, I get 20 Amps during start up, but still only 8-10 running under load.

    IMPORTANT***I noticed when it trips at 8-10 amps under load, it is NOT generating a CBC_Limit fault or LOCK_ILIMIT fault, it just generates ABN_SPEED fault.   Maybe its not actual hitting the current limit but is losing synch for some other reason.

    I have a question of vocabulary...The word "closed loop" in the program.. does that refer to the speed control loop? What do you call it when it achieves synch with the back EMF?  What parameters can I change to help keep is synch'ed under load?

    The start up is a four step process correct...Align, Open Loop ramp, Synch, Closed loop speed control..correct? 

    We have great trouble with Synch.  Slight changes in some parameters and she won't transition to running. Every one who attempts to use this chip will face this challenge. I got my motor to run by laborious trial and error, changing parameters one step at a time.  Ti needs to write a manual about how the four steps actually work and what each parameter does so we can make intelligent parameter choices.  

    Can we eliminate the closed loop control so is just runs at whatever sped the bus voltage will allow? I'm thinking if we can turn off closed loop, then we can concentrate on keeping it synched.

    Let me know if there are parameters that affect synching. 

    Its possible the closed loop control is whats dropping, but I'd like to investigate one thing at a time. 

    How did you get your jons file into this E2E chat system? I'd like to send you my file but I need step by step instructions. Browse or drag and drop doesn't seem to work in the E2E world. 

      

  • Phil,

    Thanks for the detailed explanation!

    Yes, current limit is not the issue here. 

    Startup is three step process: Align->Open loop->Closed loop. 

    In "Open loop" we do a blind commutation where we do not know the BEMF zero crossings.

    In "Closed loop" we commutate based on the BEMF zero crossings. In this stage, we operate the motor in "voltage mode", "Speed mode",  "Power mode" based on how CLOSED_LOOP_MODE is configured. In "Voltage mode", maximum motor speed is based on the DC bus voltage. In this mode, when we set the PWM duty cycle to 50% duty, device will apply 50% of DC bus voltage. In "Speed mode" and "Power mode", we run an internal PI controller to regulate the motor speed and power.  

    Can you configuring the CLOSED_LOOP_MODE to "Disabled" and see if this works? Configuring CLOSED_LOOP_MODE to "Disabled" enables voltage mode. 

  • The GUI doesn't stay connected now.  I've restarted the GUI 8 times, the first 5 times is said "cannot connect to TI cloud agent".  The last 3 times it connects, but as soon as I attempt to change anything it says " There is an issue with device connectivity.  Please restart the GUI"   I restarted my Laptop twice. My internet connection is good. I'm dead in the water now.  My laptop in only 6 months old.

  • After several more restart attempts it complained about the run time engine not being install properly.  I uninstalled the run time engine and the GUI, reinstalled it, it still didn't work, then it complained about the not being able to connect to the "Ti cloud agent". I Restarted everything in this order: launch the GUI, plug in the USB, power up the DC bus of the EVM board.  Now it's working again.

    Using my file, it trips at the same ~10A current level in closed loop speed mode and ~10amps with closed loop disabled. The trip is always ABN_SPEED.  I do have a red light for "supply overvoltage protection status DRV-OFF" but it always red , running or tripped. I tried all the settings of ABN-SPEED, 1000hz, 2000hz, 3000hz, 4000hz, and all the number of cycles 2,4,6,8; nothing has any effect.  If I disable the ABN_SPEED trip, it stops running at the same load, then starts squealing, and I have to turn everything off and go back though my start sequence to get it working again.  

    With close loop disabled, if it's not hitting the current limit, what could be causing the ABN_SPEED trip? 

    Our motor has an external rotor and I'm loading it by just squeezing it with my hand.  I'm running ~580rpm closed loop disabled an 430rpm in speed mode. It a 16pole machine. I'm using I2C to set the speed.  In closed loop disabled, I guess the speed I'm commanding is actually the % voltage applied to the motor?   

    Is there a way I can monitor the current in the Monitor status parameters Window? Perhaps it tinks the current is very high because of a scaling error. 

        

  • Hi Phil,

    I do have a red light for "supply overvoltage protection status DRV-OFF" but it always red , running or tripped

    Do you see this red light in the "Fault status" section located on right side of the GUI?

    Can you share your device register settings by clicking File->Save registers and then upload to the e2e post by clicking "Insert"->"Image/Video/File"? 

  • I do have a red light in 3 places,  at the top next to Fault Status, in the middle next to "supply overvoltage protection status DRV-OFF" and near the bottom next to ABN_SPEED. When I clear faults, ABN_SPEED goes away until I load it too much and it trips again.  the red light next to DRV-OFF sometimes is not there but I haven't correlated what makes it go away. 

    I would like to send my file using "Insert"->"Image/Video/File" but I can't figure out how. I've tried drag and drop, I've try typing in a file path. What steps do you use?

    We have a 10,000 piece immediate application waiting for me to figure out how to get this chip up to 30Amps.  

    Let know if I can relax the BEMF detector so it keeps working when there is much frequency dither. 

  • Phil,

    I need the register values to debug this issue. After you click "Image/Video/File", do you see a window pop up as shown below?

    Click "Upload" and navigate to the folder where you have saved the .JSON file and click "Ok". If this still doesn't work, can you go to "Register map" tab in the MCT8329EVM and take a screenshot of the register map and upload the image? 

    Regards,

    Vishnu

  • Something has happened to the E2E forum. The reply button is gone after every post except the first one, So I'm replying to the first post. Instead of "Reply" after a post is shows ^0true^.

    Insert photo is not longer working either.  When I press Insert, I see the dialog box you showed me, but I have no ability to get anything in the box, put in a URL does nothing, putting in a file path does nothing, drag and drop into the box or into the post does nothing. I'm using Chrome. 

    My email is Phil@InventionH.com. If you email me I'll respond with my jons file. 

  • Ok the problem with reply was that I was not logged on. 

  • I see the Insert dialog box. 

    When I click Upload I do get a browser window, but after I select the jons file nothing happens.  When I click OK in insert dialog box nothing happens.  If I click the X in the upper right, the dialog box closes.

    Email me at Phil@InventionH.com

  • I tried using Edge on a different computer, same problem, nothing happens when I select my jons file using the Image/file dialog box, the OK button does nothing.

    I also tried to drag and drop my jons file directly into this window which seemed to do something, but I don't see anything, nor do I see an attachment, do you see it?

  • Phil, 

    I just sent you an email.

    Regards,

    Vishnu