Hello, I have a little issue related to a project I'm building.
It's a medical device called string phantom used for Quality Assurance of Ultrasound machines - blood flow velocity confirmation.
Construction is simple, a string travels between pulleys and mimics the fluid flow.
To build it I've used:
- Arduino Mega board
- touch screen
- BLDC motor (190KV sensorless)
- BLDC driver (500W Brushless Motor DC 12V-36V PWM Control Driver Board)
- laptop power supply (12V 3A)
Generally, it works as intended, but I'm currently changing the control of the motor from ESC to PWM Board controller as I thought ESC was causing a little fluctuation in motor speed. By that I mean you can clearly hear it despite of PWM signal out of Arduino to ESC being locked.
I've changed ESC to mentioned board and I've noticed the same issue. I've recently acquired an oscilloscope (Hantek 1008C) and checked the PWM output from Arduino. It is slightly unstable according to my oscilloscope.
- is that just aliasing as my oscilloscope is not that good and the PWM signal is fine?
- what is the reason for motor fluctuation and how can I fix it? Is it too weak power supply? or the fact that I'm using it to power up Arduino (power adapter input) and motor at the same time? What filters I can add to remove this phenomenon?
if you can't tell, I don't have much experience with electronics...