HFI Noise Reduction?

[zhlab128]

Running HFI with MK5 works great, it's just too noisy, is there anything you can do to reduce it?
Seeing that VESC has 45DegV0V7 mode, can it be easily integrated? I also tried, the code is more complicated, I don't know where to start.
Thank you for the great project.

[rombrew]

You can play with the parameters frequency and amplitude of injection also try random waveform type. All this is described in doc/HighFrequencyInjection.md.

About VESC as I understand from sources it uses high PWM frequency with twice update per cycle. In other words, the injection frequency should be moved beyond audible range. I am not sure about my EKF observer in phobia to work with injection as high as half PWM frequency (should be ok). Also note that maximum PWM frequency is around 30 kHz on stm32f4xx due to many calculations in EKF and in core functions.

Another way is to utilize native PWM current ripple but this requires a new time diagram and making several current samples per PWM cycle. I am not ready to implement this yet and I do not think I will fit into stm32f4xx with my volume of calculations.

[zhlab128]

Does the "native PWM current ripple" method refer to the "Fundamental PWM Excitation" method? Are there any similar references? Thank you.

[rombrew]

Yes this is conventional name of the method I said before.

[rombrew]

I have done some tests of different waveform of injection, check the latest commits.

Waveform	Frequency	Notes
SINE	Up to half PWM	May be loud at low frequencies (default ~4.7 kHz)
SQUARE	Unconfigurable (PWM/2)	The quietest waveform (~14 kHz)
RANDOM	Up to half PWM	May be loud (noisy) but provides a bit more torque (no objective measurements to confirm)