This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

MCF8315EVM: Maximum speed is not reached.

Part Number: MCF8315EVM
Other Parts Discussed in Thread: MCF8315A

Tool/software:

I have a 200revs per second maxon motor with 3 pole pairs.

I am only able to reach 100revs per second after that I can increase the speed demand but the motor does not respond.

What might limit the maximum speed?

At present I am using Motor Studio 0.1.9 with the MCF8315EVM and supplying the board with 24V which is the rated motor voltage

please find the motor datasheet attached.

ECX FL32S KLA STD 24V b81626dfef55_1.pdf

  • Hi John,

    To help me identify the issue, could you please save your register configurations into a JSON file using the File menu and attach the file here:

    One thing that can be limiting your speed could be your closed loop current limit setting [ILIMIT]. Could you please make sure that it's set to at least 1.8A? (You can try increasing this and see if the motor can reach higher speed). If there's any load on your motor, it would require more current to maintain at a constant higher speed.

    Regards,
    Eric C.

  • {
    "signature":"oneui-register-data",
    "data":[
    [
    {
    "idx":0,
    "id":"ISD_CONFIG",
    "value":"0x64738C20"
    },
    {
    "idx":1,
    "id":"REV_DRIVE_CONFIG",
    "value":"0xA8200000"
    },
    {
    "idx":2,
    "id":"MOTOR_STARTUP1",
    "value":"0x656A8790"
    },
    {
    "idx":3,
    "id":"MOTOR_STARTUP2",
    "value":"0xBB06600C"
    },
    {
    "idx":4,
    "id":"CLOSED_LOOP1",
    "value":"0x1B3583C5"
    },
    {
    "idx":5,
    "id":"CLOSED_LOOP2",
    "value":"0x9BADA18A"
    },
    {
    "idx":6,
    "id":"CLOSED_LOOP3",
    "value":"0x0F251820"
    },
    {
    "idx":7,
    "id":"CLOSED_LOOP4",
    "value":"0x64723840"
    },
    {
    "idx":8,
    "id":"SPEED_PROFILES1",
    "value":"0x00000000"
    },
    {
    "idx":9,
    "id":"SPEED_PROFILES2",
    "value":"0x00000000"
    },
    {
    "idx":10,
    "id":"SPEED_PROFILES3",
    "value":"0x00000000"
    },
    {
    "idx":11,
    "id":"SPEED_PROFILES4",
    "value":"0x800D0000"
    },
    {
    "idx":12,
    "id":"SPEED_PROFILES5",
    "value":"0x00000000"
    },
    {
    "idx":13,
    "id":"SPEED_PROFILES6",
    "value":"0x00000000"
    }
    ],
    [
    {
    "idx":0,
    "id":"FAULT_CONFIG1",
    "value":"0xF7704106"
    },
    {
    "idx":1,
    "id":"FAULT_CONFIG2",
    "value":"0xF5F00888"
    }
    ],
    [
    {
    "idx":0,
    "id":"INT_ALGO_1",
    "value":"0xA433637D"
    },
    {
    "idx":1,
    "id":"INT_ALGO_2",
    "value":"0x000002E3"
    }
    ],
    [
    {
    "idx":0,
    "id":"PIN_CONFIG",
    "value":"0x00000002"
    },
    {
    "idx":1,
    "id":"DEVICE_CONFIG1",
    "value":"0x00101462"
    },
    {
    "idx":2,
    "id":"DEVICE_CONFIG2",
    "value":"0xC000F00F"
    },
    {
    "idx":3,
    "id":"PERI_CONFIG1",
    "value":"0xC1C01F00"
    },
    {
    "idx":4,
    "id":"GD_CONFIG1",
    "value":"0x98450100"
    },
    {
    "idx":5,
    "id":"GD_CONFIG2",
    "value":"0x80200000"
    }
    ],
    [
    {
    "idx":0,
    "id":"GATE_DRIVER_FAULT_STATUS",
    "value":"0x00000000"
    },
    {
    "idx":1,
    "id":"CONTROLLER_FAULT_STATUS",
    "value":"0x00000000"
    }
    ],
    [
    {
    "idx":0,
    "id":"ALGO_STATUS",
    "value":"0x0EC2EF94"
    },
    {
    "idx":1,
    "id":"MTR_PARAMS",
    "value":"0x00000000"
    },
    {
    "idx":2,
    "id":"ALGO_STATUS_MPET",
    "value":"0x04000000"
    }
    ],
    [
    {
    "idx":0,
    "id":"ALGO_CTRL1",
    "value":"0x20000000"
    }
    ],
    [
    {
    "idx":0,
    "id":"ALGO_DEBUG1",
    "value":"0xD1670000"
    },
    {
    "idx":1,
    "id":"ALGO_DEBUG2",
    "value":"0x00000000"
    },
    {
    "idx":2,
    "id":"CURRENT_PI",
    "value":"0x0301011E"
    },
    {
    "idx":3,
    "id":"SPEED_PI",
    "value":"0x03A402A4"
    },
    {
    "idx":4,
    "id":"DAC_1",
    "value":"0x00000000"
    },
    {
    "idx":5,
    "id":"DAC_2",
    "value":"0x00000000"
    }
    ],
    [
    {
    "idx":0,
    "id":"ALGORITHM_STATE",
    "value":"0x00200009"
    },
    {
    "idx":1,
    "id":"FG_SPEED_FDBK",
    "value":"0x06026758"
    },
    {
    "idx":2,
    "id":"BUS_CURRENT",
    "value":"0x00000000"
    },
    {
    "idx":3,
    "id":"PHASE_CURRENT_A",
    "value":"0xFFFE0000"
    },
    {
    "idx":4,
    "id":"PHASE_CURRENT_B",
    "value":"0x00040000"
    },
    {
    "idx":5,
    "id":"PHASE_CURRENT_C",
    "value":"0x00020000"
    },
    {
    "idx":6,
    "id":"CSA_GAIN_FEEDBACK",
    "value":"0x00010000"
    },
    {
    "idx":7,
    "id":"VOLTAGE_GAIN_FEEDBACK",
    "value":"0x00000001"
    },
    {
    "idx":8,
    "id":"VM_VOLTAGE",
    "value":"0x0331C000"
    },
    {
    "idx":9,
    "id":"PHASE_VOLTAGE_VA",
    "value":"0x00000000"
    },
    {
    "idx":10,
    "id":"PHASE_VOLTAGE_VB",
    "value":"0x00000000"
    },
    {
    "idx":11,
    "id":"PHASE_VOLTAGE_VC",
    "value":"0x00000000"
    },
    {
    "idx":12,
    "id":"SIN_COMMUTATION_ANGLE",
    "value":"0x052EC368"
    },
    {
    "idx":13,
    "id":"COS_COMMUTATION_ANGLE",
    "value":"0x06154764"
    },
    {
    "idx":14,
    "id":"IALPHA",
    "value":"0xFA7A0000"
    },
    {
    "idx":15,
    "id":"IBETA",
    "value":"0x026C12FD"
    },
    {
    "idx":16,
    "id":"VALPHA",
    "value":"0x0007427A"
    },
    {
    "idx":17,
    "id":"VBETA",
    "value":"0x004E4432"
    },
    {
    "idx":18,
    "id":"ID",
    "value":"0xFD5E836A"
    },
    {
    "idx":19,
    "id":"IQ",
    "value":"0x056B88F8"
    },
    {
    "idx":20,
    "id":"VD",
    "value":"0x000870B9"
    },
    {
    "idx":21,
    "id":"VQ",
    "value":"0x005FBD06"
    },
    {
    "idx":22,
    "id":"IQ_REF_ROTOR_ALIGN",
    "value":"0x00000000"
    },
    {
    "idx":23,
    "id":"SPEED_REF_OPEN_LOOP",
    "value":"0x03FFFE94"
    },
    {
    "idx":24,
    "id":"IQ_REF_OPEN_LOOP",
    "value":"0x1332EAC0"
    },
    {
    "idx":25,
    "id":"SPEED_REF_CLOSED_LOOP",
    "value":"0x05167000"
    },
    {
    "idx":26,
    "id":"ID_REF_CLOSED_LOOP",
    "value":"0x00000000"
    },
    {
    "idx":27,
    "id":"IQ_REF_CLOSED_LOOP",
    "value":"0x0E000000"
    },
    {
    "idx":28,
    "id":"ISD_STATE",
    "value":"0x00000005"
    },
    {
    "idx":29,
    "id":"ISD_SPEED",
    "value":"0x00000000"
    },
    {
    "idx":30,
    "id":"IPD_STATE",
    "value":"0x00040005"
    },
    {
    "idx":31,
    "id":"IPD_ANGLE",
    "value":"0x0694EE9D"
    },
    {
    "idx":32,
    "id":"ED",
    "value":"0x00000000"
    },
    {
    "idx":33,
    "id":"EQ",
    "value":"0x00000000"
    },
    {
    "idx":34,
    "id":"SPEED_FDBK",
    "value":"0x03AFB37F"
    },
    {
    "idx":35,
    "id":"THETA_EST",
    "value":"0x01A72785"
    }
    ],
    [
    {
    "idx":0
    }
    ]
    ]
    }

  • I couldnt get this web interface to let me upload the json file so I have copied the contents into the previous text box

  • experimentally I set ILIIMIT to 4.375A as the data sheet says the stall current could go up to 15.9A

    it makes no difference

  • I have no load on the motor, but the application is to spin a small mirror so the load will be small

  • Hi John,

    I just noticed that the datasheet indicates that this motor has 6 pole pairs instead of 3. Could you please try setting the [MAX_SPEED] register to 1220Hz?

    I calculated this using the equation

    Also, it looks like you have non-zero values configured in [CURR_LOOP_KP] and [CURR_LOOP_KI]. Usually these are only manually tuned for advanced optimizations and is generally not needed, since the MCF8315A's algorithm can determine the current loop KP and KI values automatically if you set these registers to 0. Not sure if you configured these values intentionally or not.

    On the other hand, [SPD_LOOP_KP] and [SPD_LOOP_KI] do need to be set to non-zero values by the user, otherwise the device will attempt to run MPET to measure them when a speed command is issued.

    Regards,
    Eric C.