Hey guys, I continue to try to make a very quiet fan driver. I am getting a persistent hum/ringing sound that increases in pitch with RPM. It increases slightly with voltage but not that much, and it sort of levels off. It occurs even in fully open loop mode, where nothing happens except looping…

I never tried to change it, so I would think it is the default 25kHz which the docs say is the default for STM32 chips. Yeah I should try changing it, see if it makes any discernible difference. edit: tried changing it to 35000, it doubles current consumption (the capacitors and inductors are remo…

Yes! If the G4 is running 170Mhz (170.000.000 Hz) 25Khz has a resolution of (without pre-scaler) = 6800. If you double the freq. you get half the res.

25kHz is already not in the audible range. Increasing the frequency might only increase switching losses ? [EDIT] And make the deadtime represent an even higher pourcentage of the duty cycle

[image] Anthony_Douglas: I think maybe my commanded changes are not being obeyed. How do you change the freq. for STM there are actually two ways, which can lead to some confusion. Here; // default pwm parameters #define _PWM_RESOLUTION 16 // 12bit #define _PWM_RANGE 65535.0f // 2^12 -1 = 4…

I put driver.pwm_frequency = 25000; just before driver.init in the setup section of the code?

You may have to change these values not sure if this is the best implementation. _setPwm(((STM32DriverParams*)params)->timers[2], ((STM32DriverParams*)params)->channels[2], _PWM_RANGE*dc_b, _PWM_RESOLUTION); @runger The confusion is a result of using this: setOverflow((uint32_t)PWM_freq, HERTZ_F…

[image] Anthony_Douglas: driver.pwm_frequency = 25000; That should work… The HAL interface to the timers is a bit complicated. I would actually prefer to do it a different way. If I understand correctly what HAL is doing we set the frequency in Hz and the desired resolution (fixed at 4095) a…

The resistors were the wrong size, 10 ohm instead of 1 ohm, have to wait till tomorrow to get some more. But this phenomenon is bizarre. With 150uH inductors followed by a 10uf capacitor, how can any such brief voltage or current transient sneak by unaffected? And yet adding them makes no audible…

[image] Anthony_Douglas: like 300 mA, it’s really not much as the stuff around here goes I’m curious why didn’t you then get the Mosquito, and get it over with. It’s based off a cheap TI $2 commercial integrated 3PWM driver, really tiny, you can put G071 instead of G031, and you can stick a s…

Because I didn’t know about the mosquito :(. That is the only reason. I looked at the recommended hardware, and it wasn’t there IIRC. I also thought that there were issues with 3 pin pwm, however I think I was probably wrong about that. Update: I hypothesized that during the dead period when nei…

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Changing PWM dead time or other parameters with B-G431B-ESC1 board

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