some question about InstaSPIN

1. Torque must be calculated by an external function. see User.c USER_computeTorque_Nm and similar.
2. 12b is running encoder feedback velocity + torque FOC control. Your curent is being controlled to meet the needs of the velocity controller. You can set a limit on the velocity controller using USER_MOTOR_MAXIMUM_CURRENT
3. Inertia and friction are not load dependent. You want to include any coupling elements, but low load during ID.
4. under a stall condition the current will saturate to the limit of the controller.

1.i will see that function later

2.if i had set USER_MOTOR_MAXIMUM_CURRENT = 20A, why did i found current feedback reach very large value occasionally(40A , 60A OR 80A)

3.you means that  Inertia and friction could be using with any load, and the value needn't be changed with load rapid change.

4. under a stall condition, if i set  USER_MOTOR_MAXIMUM_CURRENT = 20A, software will output the value lower than 20A,but not 20A+?

2. USER_MOTOR_MAXIMUM_CURRENT only sets the limit on the output of the velocity controller, which is the input to the torque controller (Iq_Ref_A). If your control is not working correctly while the reference may be set to the limit the actual may not.

3. yes

4. again, you are setting a limit to the output of the velocity controller, not the actual current of the motor. it seems like your electrical angle is not correct, meaning that you aren't able to produce the torque correctly. I would look at the alignment of your rotor and mechanical encoder to the electrical angle.

to confirm again,
Inertia and friction should be identified with no/low load, and these result applie to all applications,
no matter how much mechanical structure or load change

and there have a new error is if i change motor speed from 5000rpm to -5000rpm with 10000 rps^2 acclerate, current may became much higher than USER_MOTOR_MAXIMUM_CURRENT, does it means electrical angle is not correct?
if so, how could i find out the error and solve it?

Chang,

chang lianqing said:

Inertia and friction should be identified with no/low load, and these result applie to all applications,
no matter how much mechanical structure or load change

The Inertia and Friction identification should be done with as little load as possible.  And the results will work for any amount of load change.  But if the inertia of the system (i.e. anything rigidly coupled to the motor) changes by more than 4x-6x you need to update the inertia value.  So if the mechanical structure is changing you might need to update the inertia value.

so if the system's gear did not change, just load change(became very heavy) when motor running, i also needn't changing my inertia?

Can you provide some additional details about your application? When you say it becomes very heavy that could imply either a load change or an inertia change.

sorry for my pool drawing.

this is my question, if i add a 100kg(or any kg) load to system, what should i do with the inertia parameter?

No worries, your drawing was very clear. In the case you describe the inertia should only be the motor + gearing + belt. The objects on the belt I would not consider inertia.

please take a look on my another question, thank you

hello,
i found that if the load was too heave, the inertia must be increase. Otherwise, the whole system will be in an unstable state.
motor + gearing + belt not change.

Hello Chang,

Are you still experiencing issues or have you fixed the problem?

Best Regards,
Adam Dunhoft