Solution of great noise on SD700 servo motor during rotation

Fault Name:

Great noise on SD700 servo motor during rotation.

Fault Symptom:

SD700 series servo motors generate too much noise during rotation at site or in the laboratory.

Causes:

The servo gain is too high.

The current sampling doesn’t calibrate zero drift.

The initial angle is wrong.

Solutions:

Decrease the servo gain.

Calibrate zero drift by the current sampling.

Recalibrate the initial angle.

Analysis:

The noise of the motor is basically accompanied by the fluctuation of the motor speed and torque. Firstly, confirm whether the inertia ratio is correct. If the inertia ratio is uncertain, you can first reduce the inertia ratio; after confirming it, reduce the gain of the speed loop and position loop, and observe the upper machine oscilloscope and the commanded speed and torque feedback waveforms. If the fluctuations become slighter that indicates the noise is caused by high servo gain.

If the above measure is invalid, you could check the parameters PnE51/PnE52 (manufacturer parameter), if the parameter is “0”, that means it was not calibrated before and you could manually do it by the auxiliary parameter Fn103. Normally PnE51/PnE52 is about ±100~300 . If you do not have a factory password, you can also automatically calibrate via Fn103, but you cannot see the values before and after calibration. After the software is upgraded, zero drift needs to be calibrated again; otherwise problems such as inaccurate inertial recognition and great noise would appear.

If the initial motor angle deviation is too large, it will also cause instability of the motor during rotation. You could use the built-in initial angle test function of the driver to recalibrate the angle, and to ensure the accuracy of the initial angle, you need to disconnect the load and perform the following steps:

SD700 electrical angle verification procedure

1    Pn030    1706    Manufacture parameter password

2    PnF1B    0    Electrical angle clear

3    Pn792    1    Write electrode parameters to the encoder

4    Fn002        Soft reset

5    Pn030    1706    Manufacturer parameter password

6    PnEF7    1    Rectangular waveform

7    PnEF9    5000    Rated current

8    PnEFB    1    Artificial angle D shaft current

9    PnEFD    1    Enable

10    PnF1B    =360-Un004    Initial electrical angle

11    PnEFD    0    Turn off enable

12    Pn792    1    Write the motor parameters into the encoder

13    Fn002        Soft reset