TMS320F28027F: No force in lab4 torque mode

Luo XiuFeng

Part Number: TMS320F28027F
Other Parts Discussed in Thread: LAUNCHXL-F28027F

My development board is LAUNCHXL-F28027F + BOOSTXL-DRV83

I use lab4 torque control to adjust the torque. I gave the value of IqRef_A 0.2. The motor started to rotate. I saw that the current was about 0.3A and the speed displayed by the Speed_krpm variable was about 1600rpm. When I touched the rotor of the motor with my hand At that time, it stopped easily. At this time, the current became 0.10A. Why is the motor weak? Can I stop it easily? How can I adjust it? To generate relative resistance?

over 4 years ago

0 Yanming Luo over 4 years ago

TI__Guru** 115440 points

The torque current can't generate sufficient force to overcome the load you added, you can increase the torque current, and you might use a dynameter, or brake, or clutch to add the right load to the motor that should be more workable to tune the control.

0 Luo XiuFeng over 4 years ago in reply to Yanming Luo

Intellectual 676 points

You may not understand what I mean, I mean by adjusting iqref_ The value of a variable, the motor can rotate and reach the maximum speed, but at the maximum speed, about 3000rpm, I use my hand to try to stop the motor rotation, the motor can be easily stopped by hand, I feel that although the motor has speed, but the motor has no force!

0 Yanming Luo over 4 years ago in reply to Luo XiuFeng

TI__Guru** 115440 points

As mentioned above, the motor can run to the maximum speed with a small torque current if there is no load on its shaft, but the torque current is still not enough to overcome the load you added. That's why we recommend you use a dynamometer or brake/clutch to do a test since the right load can't be added to the motor by your hand.

If you can't have such requirements, please increase the torque current, or connect the shaft of the motor to another motor for the test.

0 Luo XiuFeng over 4 years ago in reply to Yanming Luo

Intellectual 676 points

As you said, after I added the current to 2a, I could feel the force with my hand, but now a new problem appeared. I disabled the forced angle, gMotorVars.Flag_enableForceAngle = false, and used the dynamometer to turn the motor Connect the dynamometer to run in the opposite direction of the motor:

1. When the force of the dynamometer is equal to the force output by the motor, they are stationary, but the interesting thing is that the motor will jitter back and forth while remaining stationary. Is this a fast angle problem? I tried EST_setAngle_pu(obj->estHandle, EST_getAngle_pu(obj->estHandle)); but it didn't seem to work. How can I solve this problem?

2. I am not sure if this phenomenon occurs when the dynamometer drives the motor to rotate in the opposite direction. It seems that the jitter is not easy to detect?

+1 Yanming Luo over 4 years ago in reply to Luo XiuFeng

TI__Guru** 115440 points

Q1, that's normal. You are using the sensorless instapsin-foc, which is difficult to achieve a full torque output stability and spin the motor smoothly at zero or low speed. You have to implement sensored-foc if you want to run/start the motor with a heavy/full load at low speed.

Or you might take a look at chapter 14 (Managing Full Load at Startup, Low-Speed and Speed Reversal) in InstaSPIN User's Guide if you have to implement the sensorless-FOC on your applications.

http://www.ti.com/lit/ug/spruhj1h/spruhj1h.pdf

Q2. Yes, as replied to Q1.

0 Luo XiuFeng over 4 years ago in reply to Yanming Luo

Intellectual 676 points

In method 2, I continued to increase the current of IqRef_A, I used the load to drive the motor to move in the opposite direction, and the motor jittered back and forth very obviously. Small current does not. In non-inductive control, is there any way to drive the motor to rotate in the direction? And the torque of the motor is maintained smoothly? Can I only use sensors with sensors? Our products are very cost sensitive.

0 Luo XiuFeng over 4 years ago in reply to Yanming Luo

Intellectual 676 points

In addition, if the hall project is added, can this problem be solved? 28027 can support hall, right?

0 Yanming Luo over 4 years ago in reply to Luo XiuFeng

TI__Guru** 115440 points

The F28027 can support both hall sensor and incremental encoder interfaces. You'd better use the encoder if you need to achieve precise speed control at low speed with sensored-FOC.

0 Luo XiuFeng over 4 years ago in reply to Yanming Luo

Intellectual 676 points

I didn't find QEP module in f28027, are you sure it can be used for encoder? In addition, does Ti currently support incremental encoders?

0 Yanming Luo over 4 years ago in reply to Luo XiuFeng

TI__Guru** 115440 points

Sorry for confusing you. The F28027 doesn't support QEP. You need to use the other C2000 controllers, like F2803x, F2806x, F28002x... as the links below to find the right device.

https://www.ti.com/microcontrollers-mcus-processors/microcontrollers/c2000-real-time-control-mcus/products.html

C2000 controller can support both incremental encoder or absolute encoder as well. Please take a look at the following link.

https://www.ti.com/microcontrollers-mcus-processors/microcontrollers/c2000-real-time-control-mcus/applications/absolute-encoder.html#position-sensor-management

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMS320F28027F: No force in lab4 torque mode