MCF8316C-Q1: Some issues for debugging the low-inductance motor

Hi Alex,

Please install MOTOR STUDIO 0.1.18 which is published online, available for download. In this we have removed default value and instead allow use a template file.

I modified you file and adding here below.

You need to measure R, L as explained in the data sheet, please note the parameter values are per phase quantity.

Example if you read Phase to Phase resistance please divide it by 2 and program it.

For KE the motor data sheet says 53mV/ rad/s  , we need mV/Hz, please convert to Hz which is equivalent to 332mV/ Hz

Answer to other questions

Q-1, There could be two reasons,

1. When the motor resistance is very high  and MPET current setting for IPD is set high so that current   not possible to reach to set current threshold for IPD to complete fault happens. To overcome this reduce the MPET IPD current or if you already know the Resistance and Inductance (per phase) program them or using LCR meter measure them and program.

2. Another reason will be check for DRVOFF switch position on the EVM, if DRV is cutoff due to this there will not be any current output and this error shows up

Q-2,  Minimum inductance is 6uH, can you re check (measure ). If it is less than then PWM switching frequency will not be able to maintain the continuous winding current,

For rest of the questions as per motor data sheet BEMF Contant is 333mV/Hz, can you measure manually if possible and confirm?

Thanks and Best Regards

Venkatadri S

Hi Venkatadri,

Venkatadri Shantaram84961 said:

Please install MOTOR STUDIO 0.1.18 which is published online, available for download.

What I used is just MoorStudio:

Venkatadri Shantaram84961 said:

I modified you file and adding here below.

I could not see your file, could you try to attach it again?

Venkatadri Shantaram84961 said:

You need to measure R, L as explained in the data sheet, please note the parameter values are per phase quantity.

The parameters were given by the motor supplier via the actual measurement and they should be right. Is there any compatibility problem between MCF8316C and this motor?

Actually this motor has hall sensors in it. MCF8316C has FOC and it says "Improved acoustic performance", and we have high requirement for acoustic performance, that's why we choose MCF8316C to drive this motor. Need we to change to use other driver?

Venkatadri Shantaram84961 said:

1. When the motor resistance is very high  and MPET current setting for IPD is set high so that current   not possible to reach to set current threshold for IPD to complete fault happens. To overcome this reduce the MPET IPD current or if you already know the Resistance and Inductance (per phase) program them or using LCR meter measure them and program.

I changed the MPET IPD current to the minimum value 0.1A, then run MPET in the Quick Spin, the motor just vibrated and could NOT rotate.

If this value was changed to higher value such as 0.5A or more, "MPET_IPD_FAULT" was triggered.

Venkatadri Shantaram84961 said:

2. Another reason will be check for DRVOFF switch position on the EVM, if DRV is cutoff due to this there will not be any current output and this error shows up

I used EVM refering to MCF8316A_EVM_TuningGuide.pdf, and DRV_OFF was set as the following, so it should not be this reason,

Venkatadri Shantaram84961 said:

Q-2,  Minimum inductance is 6uH, can you re check (measure ). If it is less than then PWM switching frequency will not be able to maintain the continuous winding current,

So if some motor's inductance is less than 6uH, MCF8316C could not drive it normal, right?

Venkatadri Shantaram84961 said:

For rest of the questions as per motor data sheet BEMF Contant is 333mV/Hz, can you measure manually if possible and confirm?

I would talk with my hardware colleague and check if we could measure by ourselves or not.

Thanks,

Alex

Hi Alex,

Sorry I missed to attach the JSON file.

IPD injects current with a magnitude configured, if V/R is not enough current will never reach the threshold. 

Where V is applied voltage (terminal voltage) and the R is Per phase resistance (Phase to CT).

When IPD current is not able to reach set threshold device sets IPD Fault, hence I took two possible reasons and one you confirmed DRVOFF switch is proper position.

Regarding Inductance, recommended range is 6uH to 20mH , PWM frequency should be selected min 5 times the R/L time constant .

Please re check inductance also.

I am still copying the JSON you can use to run , please re confirm the Inductance and BEMF constant of the motor.

Hi Venkatadri,

Thanks a lot for your advice. We re-checked inductance and BEMF Constant by manual, and were amazed to find the parameters provided by the motor supplier were wrong.. The values we measured are as following:

Wire Resistance: 11.5Ω

Wire Inductance: 4.7mH

BEMF Constant: around 20mV/Hz

So [Q-2]&[Q-3] are solved now. For [Q-1], we still could not run MPET, how should we measure the avalible Kp/Ki coefficient for speed loop without MPET?

Thanks,

Alex

Hi Alex,

Is this motor on load? What type of load?

MPET for mechanical is tuned considering the load property.

When running MPET for mechanical do not check KE measurement, just check MECH and testing.

I am writing down a flow chart about how to use MPET, I will share to you by end of this week.

Thanks and Best Regards

Venkatadri S

Hi Venkatadri,

Venkatadri Shantaram84961 said:

Is this motor on load? What type of load?

The motor needs to push the display screen via the scew in limited range and limited time. The product has not been assembled yet, so we tested the motor with no load. But we had purchased a simulated load, and it would arrive next week.

Venkatadri Shantaram84961 said:

I am writing down a flow chart about how to use MPET, I will share to you by end of this week.

OK, thanks a lot.

By the way, based on the json you provided above, I modified some parameters as following:

{
"signature":"oneui-register-data",
"data":[
[
{
"idx":0,
"id":"ISD_CONFIG",
"value":"0x6C230C3C",
"addr":"0x00000080"
},
{
"idx":1,
"id":"REV_DRIVE_CONFIG",
"value":"0xA8200000",
"addr":"0x00000082"
},
{
"idx":2,
"id":"MOTOR_STARTUP1",
"value":"0x4964C3C0",
"addr":"0x00000084"
},
{
"idx":3,
"id":"MOTOR_STARTUP2",
"value":"0x941A6005",
"addr":"0x00000086"
},
{
"idx":4,
"id":"CLOSED_LOOP1",
"value":"0x0E3191B9",
"addr":"0x00000088"
},
{
"idx":5,
"id":"CLOSED_LOOP2",
"value":"0x99E5D7C3",
"addr":"0x0000008A"
},
{
"idx":6,
"id":"CLOSED_LOOP3",
"value":"0x25800002",
"addr":"0x0000008C"
},
{
"idx":7,
"id":"CLOSED_LOOP4",
"value":"0x288A04B0",
"addr":"0x0000008E"
},
{
"idx":8,
"id":"REF_PROFILES1",
"value":"0x00000000",
"addr":"0x00000094"
},
{
"idx":9,
"id":"REF_PROFILES2",
"value":"0x00000000",
"addr":"0x00000096"
},
{
"idx":10,
"id":"REF_PROFILES3",
"value":"0x00000000",
"addr":"0x00000098"
},
{
"idx":11,
"id":"REF_PROFILES4",
"value":"0x00000000",
"addr":"0x0000009A"
},
{
"idx":12,
"id":"REF_PROFILES5",
"value":"0x00000000",
"addr":"0x0000009C"
},
{
"idx":13,
"id":"REF_PROFILES6",
"value":"0x00000000",
"addr":"0x0000009E"
}
],
[
{
"idx":0,
"id":"FAULT_CONFIG1",
"value":"0x9EEA4326",
"addr":"0x00000090"
},
{
"idx":1,
"id":"FAULT_CONFIG2",
"value":"0xFF0220B8",
"addr":"0x00000092"
}
],
[
{
"idx":0,
"id":"INT_ALGO_1",
"value":"0xA3F540BD",
"addr":"0x000000A0"
},
{
"idx":1,
"id":"INT_ALGO_2",
"value":"0x000001A1",
"addr":"0x000000A2"
}
],
[
{
"idx":0,
"id":"PIN_CONFIG",
"value":"0x08000000",
"addr":"0x000000A4"
},
{
"idx":1,
"id":"DEVICE_CONFIG1",
"value":"0x00101464",
"addr":"0x000000A6"
},
{
"idx":2,
"id":"DEVICE_CONFIG2",
"value":"0xC000F007",
"addr":"0x000000A8"
},
{
"idx":3,
"id":"PERI_CONFIG1",
"value":"0x81681F00",
"addr":"0x000000AA"
},
{
"idx":4,
"id":"GD_CONFIG1",
"value":"0x0C000000",
"addr":"0x000000AC"
},
{
"idx":5,
"id":"GD_CONFIG2",
"value":"0x00020000",
"addr":"0x000000AE"
}
],
[
{
"idx":0,
"id":"GATE_DRIVER_FAULT_STATUS",
"value":"0x00000000",
"addr":"0x000000E0"
},
{
"idx":1,
"id":"CONTROLLER_FAULT_STATUS",
"value":"0x00000000",
"addr":"0x000000E2"
}
],
[
{
"idx":0,
"id":"ALGO_STATUS",
"value":"0x381E0004",
"addr":"0x000000E4"
},
{
"idx":1,
"id":"MTR_PARAMS",
"value":"0x00000000",
"addr":"0x000000E6"
},
{
"idx":2,
"id":"ALGO_STATUS_MPET",
"value":"0x02000000",
"addr":"0x000000E8"
}
],
[
{
"idx":0,
"id":"ALGO_CTRL1",
"value":"0x20000000",
"addr":"0x000000EA"
}
],
[
{
"idx":0,
"id":"ALGO_DEBUG1",
"value":"0x80000000",
"addr":"0x000000EC"
},
{
"idx":1,
"id":"ALGO_DEBUG2",
"value":"0x00000000",
"addr":"0x000000EE"
},
{
"idx":2,
"id":"CURRENT_PI",
"value":"0x012D012E",
"addr":"0x000000F0"
},
{
"idx":3,
"id":"SPEED_PI",
"value":"0x022A012A",
"addr":"0x000000F2"
},
{
"idx":4,
"id":"DAC_1",
"value":"0x00000000",
"addr":"0x000000F4"
},
{
"idx":5,
"id":"DAC_2",
"value":"0x00000000",
"addr":"0x000000F6"
}
],
[
{
"idx":0,
"id":"ALGORITHM_STATE",
"value":"0x00000000",
"addr":"0x00000190"
},
{
"idx":1,
"id":"FG_SPEED_FDBK",
"value":"0x04000000",
"addr":"0x00000196"
},
{
"idx":2,
"id":"BUS_CURRENT",
"value":"0x00000000",
"addr":"0x00000410"
},
{
"idx":3,
"id":"PHASE_CURRENT_A",
"value":"0x00008000",
"addr":"0x00000440"
},
{
"idx":4,
"id":"PHASE_CURRENT_B",
"value":"0x00000000",
"addr":"0x00000442"
},
{
"idx":5,
"id":"PHASE_CURRENT_C",
"value":"0x00028000",
"addr":"0x00000444"
},
{
"idx":6,
"id":"CSA_GAIN_FEEDBACK",
"value":"0x00010003",
"addr":"0x00000468"
},
{
"idx":7,
"id":"VOLTAGE_GAIN_FEEDBACK",
"value":"0x00000002",
"addr":"0x00000472"
},
{
"idx":8,
"id":"VM_VOLTAGE",
"value":"0x01ABE000",
"addr":"0x00000476"
},
{
"idx":9,
"id":"PHASE_VOLTAGE_VA",
"value":"0x00014C8D",
"addr":"0x0000047A"
},
{
"idx":10,
"id":"PHASE_VOLTAGE_VB",
"value":"0x0000DDB3",
"addr":"0x0000047C"
},
{
"idx":11,
"id":"PHASE_VOLTAGE_VC",
"value":"0x00014C8D",
"addr":"0x0000047E"
},
{
"idx":12,
"id":"SIN_COMMUTATION_ANGLE",
"value":"0x04038E8C",
"addr":"0x000004B6"
},
{
"idx":13,
"id":"COS_COMMUTATION_ANGLE",
"value":"0xF914B0C0",
"addr":"0x000004B8"
},
{
"idx":14,
"id":"IALPHA",
"value":"0xFFF80000",
"addr":"0x000004D2"
},
{
"idx":15,
"id":"IBETA",
"value":"0xFFEEADF3",
"addr":"0x000004D4"
},
{
"idx":16,
"id":"VALPHA",
"value":"0xFFA52F9E",
"addr":"0x000004D6"
},
{
"idx":17,
"id":"VBETA",
"value":"0xFF571284",
"addr":"0x000004D8"
},
{
"idx":18,
"id":"ID",
"value":"0xFFFD47C5",
"addr":"0x000004E2"
},
{
"idx":19,
"id":"IQ",
"value":"0x0012DB87",
"addr":"0x000004E4"
},
{
"idx":20,
"id":"VD",
"value":"0xFFF9C946",
"addr":"0x000004E6"
},
{
"idx":21,
"id":"VQ",
"value":"0x00BFB5EC",
"addr":"0x000004E8"
},
{
"idx":22,
"id":"IQ_REF_ROTOR_ALIGN",
"value":"0x00000000",
"addr":"0x00000524"
},
{
"idx":23,
"id":"SPEED_REF_OPEN_LOOP",
"value":"0x00000000",
"addr":"0x0000053C"
},
{
"idx":24,
"id":"IQ_REF_OPEN_LOOP",
"value":"0x06664E40",
"addr":"0x0000054C"
},
{
"idx":25,
"id":"SPEED_REF_CLOSED_LOOP",
"value":"0x00000000",
"addr":"0x000005D4"
},
{
"idx":26,
"id":"ID_REF_CLOSED_LOOP",
"value":"0x00000000",
"addr":"0x00000606"
},
{
"idx":27,
"id":"IQ_REF_CLOSED_LOOP",
"value":"0x00000000",
"addr":"0x00000608"
},
{
"idx":28,
"id":"ISD_STATE",
"value":"0x00000005",
"addr":"0x00000682"
},
{
"idx":29,
"id":"ISD_SPEED",
"value":"0x00000009",
"addr":"0x0000068C"
},
{
"idx":30,
"id":"IPD_STATE",
"value":"0x0000000C",
"addr":"0x000006C0"
},
{
"idx":31,
"id":"IPD_ANGLE",
"value":"0x00000000",
"addr":"0x00000704"
},
{
"idx":32,
"id":"ED",
"value":"0x00000000",
"addr":"0x0000074A"
},
{
"idx":33,
"id":"EQ",
"value":"0x00000000",
"addr":"0x0000074C"
},
{
"idx":34,
"id":"SPEED_FDBK",
"value":"0x00000000",
"addr":"0x0000075A"
},
{
"idx":35,
"id":"THETA_EST",
"value":"0x00000000",
"addr":"0x0000075E"
}
]
]
}

The motor could start smoothly in most cases. But sometimes the motor would vibrate a little before it switched to Closed Loop. Its current waveform is as following:

There're some pulses whose peak is out of the OL_LIMIT(here set as 0.5A), and it should be the reason why the motor vibrated before switching to Closed Loop. How to solve this issue?

Thanks,

Alex

Hi Alex,

I missed this thread, let me check this and reply to you in a day.

Thanks and Best Regards

Venkatadri S

Hi Alex,

The four pulse which you are seeing are correct. The concept sketch shows for pulse sending in all 6 vectors (0 to 360 degrees), the pulse length with be different at point near to Magnet pole. Current pulses are sent on three phases, if we probe on example phase B, 1st pulse BtoC, 2nd Pulse C2B, 3rd pulse AtoB, 4th pulse BtoA.Other two pulses will be A2C and C2A which is not visible in B and hence you see only 4.

MCF8316 uses 6 sector to search for the rotor position and this provides reliable rotor position, after successful position identification device starts generating vector at an advanced angle programmed. The advanced angle options help to smoothen the startup current which reduces acoustics, if application don't care for startup time acoustics, then device can start open loop with 90 degrees from the identified position, this starts with high torque.

Thanks and Best Regards

Venkatadri S

Hi Venkatadri,

Thanks a lot for your explaination for the IPD question. I removed the related post a few minutes ago before your reply because this question is not urgent and I want to mention it in another new thread...

Copy this IPD question here:

Another question is: we used IPD as the startup option, the corresponding current waveform was:

But it seemed that the 4 pulses(not 6 as the datasheet Figure 7-25 shows) were the same in the above waveform. Could we still use IPD as the startup option?

By the way, could you kindly help to analyze the issue mentioned in the above? Look forward to your soonest reply. Thanks a lot.

Alex Wang said:

There're some pulses whose peak is out of the OL_LIMIT(here set as 0.5A), and it should be the reason why the motor vibrated before switching to Closed Loop. How to solve this issue?

Thanks,

Alex

Hi Venkatadri,

In addition, I tried several times, and found that the previous few pulses(around 10, exclude the 4 pulses in IPD) were stable. This issue seemed to occur between open loop and closed loop(maybe handoff?).

The following is anoter waveform of this issue:

Thanks,

Alex

Hi Alex,

Open Loop acceleration looks high, I am not sure if your motor inertia can support.

Even if, start with low acceleration  value, say A1 = 10Hz/s and A2=0 , this rate generally works for many motors.

When we need to accelerate the motor faster OL_ILIMIT also matters, increasing the initial torque cam spin the motor faster , but before set any current limit make sure to set limit not exceeding the rated value. 

Looking at the waveform motor looks like not spinning to the hand off speed. 

You can also enable AUTO HANDOFF and Keep A1, A2 as mentioned.

Thanks and Best Regards

Venkatadri S

Hi Venkatadri,

Venkatadri Shantaram84961 said:

Even if, start with low acceleration  value, say A1 = 10Hz/s and A2=0 , this rate generally works for many motors.

We have to push the display screen in limited time such as 3 seconds, the current A1=75Hz/s&A2=2.5 took around 550ms to enter closed loop stage. If we decrease the A1/A2, the time would be too long, for example, A1=10Hz/s&A2=0 you mentioned would take around 5~6 seconds.

Venkatadri Shantaram84961 said:

Looking at the waveform motor looks like not spinning to the hand off speed. 

The open loop should be done, because I checked the frequency of the last 2 ones in the 10 pulses, it was near the value indicated in "Calculated Open to Close Loop Threshold(Hz)".

Thanks,

Alex

Hi Alex,

I will reply by tomorrow.

Thanks and Best Regards

Venkatadri S

Hi Venkatadri,

Is there any update?

Thanks,

Alex

Hi Venkatadri,

Thanks for your suggestion. It's more stable based on your json.

Thanks,

Alex