next topic »

[on:]

Hi all,

I'd like to read about other peoples experiences with controlling liquid flow rates by using Arduinos with DC pumps, giving them PWM input... There are some threads discussing this, but I didn't encounter any, which would share the used operation frequencies. In addition to that it seems like the thing should work fine, but still I'm not sure of my chances to run in some trouble with a pump like those from weilibao.com (see WDB-38I, I'm not allowed to post links at first post). I mean if it should work fine with just some 10% of controlled flow rate (or even from 0) and not overheat. Perhaps someone can point to a theoretical/empirical relation between PWM value and {electr. power, rotation frequency}? Are there any brushless DC motors in production, which would somehow get their coil-switching messed up by the frequent PWM power outages?
Anyway, anyone has this kind of thing running just fine, please let me know...

[Reply #1 on:]

 

Are there any brushless DC motors in production, which would somehow get their coil-switching messed up by the frequent PWM power outages?
Anyway, anyone has this kind of thing running just fine, please let me know...

Most modern brushless DC motors most commonly utilize a ESC (electronic speed controller) that interfaces to a arduino as a simple servo controlled motor. The esc handles all the 3 phase switching requirements.

Standard two wire PM DC motors are often controlled with simple PWM control through a single transistor, or more complex H-drive circuit if forward/reverse rotatation is also required. How a given motor/pump will operate with PWM is hard to say, as torque Vs rpm Vs flow rate can be very non-linear and losses and friction and headpressure can require a non zero starting value for the pwm value range that can be utilized.

Lefty

[Reply #2 on:]

Linearity is not required, the algorithm should be able to adapt or can be given some approximation. Just I'm concerned about if those pumps can actually be operating to provide relatively small flows with PWM and can they be somehow damaged or consume excessive amount of power. Well, I don't know much about this, so am I asking here.

[Reply #3 on:]

My suggestion would be to contact the company (WeiliBao) about the controller requirements of their DC brushless pumps, because it is not at all clear exactly how those pumps are powered or controlled from the information on their site.

For anybody knows, they have a built-in integrated controller (much like PC fans - which are brushless as well, despite having only positive and negative leads!), or the company has a controller specified, either that they supply, or they reccommend from another company.

Such a pump may not even be controllable from an R/C-style brushless DC motor controller (perhaps the pump needs a controller that has feedback capability, or not, or...?).

Really - you need a proper datasheet and information about this pump before you can even decide how to control it. I would look into that, first...

 

[Reply #4 on:]

Oh sure! And then you've got Chinese, who don't care answering your mails... While all others down the trade chain have no idea. Note that those pumps have two wires and running at no load seems to be not allowed (so I'd guess, they don't have any memory of previous rotor positions?).