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Brushless pump.

Parablennius

Parablennius

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5 Mar 2016
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One for any electrical wizards out there. I’d like to replace the control box that is wired between the pump and power supply ( 20 presses from full to minimum ) from a TMC12V DC brushless pump with a rheostat. This would be simple with a conventional motor but brushless dc motors have 3 wires which I understand they need. So, is this doable? Stepdown states output of 12VDC @ I AMP. Quite happy/ competent with soldering etc. TIA . Steve
 
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Brushless motors generally require a micro-controller board to do whats called PWM (pulse width modification) to regulate the speed of the motor. A simple rheostat isnt what you need, would likely not work. Square peg, round hole. The reason you have to do the 20 different presses is likely that the controller is using a single digital input (cheaper) and doing a modulo 20 on in the current count for the uController PWM duration.

Short of ripping it apart and trying to reverse engineer it, you're likely stuck with how it works now.
 
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Thanks for your reply. I’ve used PWM before to regulate conventional motors but some, Iron cored armature motors don’t like it unless it’s very high frequency. They can get hot and buzz. So do brushless PC type cooling fans. What I’m struggling with is the diagrams that I’ve seen for BLDC motors show 3 wires to the windings so which one would need to be regulated? You can see that a simple rotary rheostat would be far simpler than 20 presses each way on what is basically a very simple switch which, having dissected a couple, could possibly fail through frequent use. Think daily. Being able to use a rheostat may also bypass the use of the 10 minute “feeding” setting. I don’t mind dismantling or rebuilding electronics but I don’t really want to destroy the existing kit unless I know it’s going to work. There will be a way. I need to replace the control box with another. Cheers, Steve
 
Parablennius said:
Thanks for your reply. I’ve used PWM before to regulate conventional motors but some, Iron cored armature motors don’t like it unless it’s very high frequency. They can get hot and buzz. So do brushless PC type cooling fans. What I’m struggling with is the diagrams that I’ve seen for BLDC motors show 3 wires to the windings so which one would need to be regulated? You can see that a simple rotary rheostat would be far simpler than 20 presses each way on what is basically a very simple switch which, having dissected a couple, could possibly fail through frequent use. Think daily. Being able to use a rheostat may also bypass the use of the 10 minute “feeding” setting. I don’t mind dismantling or rebuilding electronics but I don’t really want to destroy the existing kit unless I know it’s going to work. There will be a way. I need to replace the control box with another. Cheers, Steve
Click to expand...
you wont be able to do just one without it acting up or possibly damaging it, if its brushless you need some sort of timer controller. Simply reducing the voltage on one wire isn't how to control this motor, you need to modify how long each pair of the 3 poles stay "hot" and how long the other pole stays off, while also being able to change the direction the current is going to spin the magnet. Its easier with a GIF

Changing the incoming voltage on one or even all the poles isnt going to change how fast it goes, its the switch time of each of the 6 different PWM inputs.

If you try to lower the voltage to the supply whats likely going to happen is the timing will get all messed up because its probably cheapy motor with no hall effect feedback and its just gonna vibrate like hell and not do anything besides destroy the motor with heat build up.




fig3-a-bldc-monitor-en.gif
article-2016december-how-to-power-and-fig2.jpg
 
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Have a look at Hobbywing brushless motor esc, various auction sites should help👍
I have used them in the past
 
Just to add, there are lots of other brands, however, i have found the Hobbywing brand to be very reliable
 
If you have a BLCD motor then read this article's section "Challenges of Making a BLDC Motor Speed Controller"

www.integrasources.com

BLDC Motor Controller: Design Principles & Circuit Examples

A BLDC motor controller is an efficient electronic solution that can have different circuit design options ✓ Learn more about them in this article.
www.integrasources.com www.integrasources.com

Controlling it seems to require hardware and software and it seems to be not something standard of the shelf. For DIY you would need quite some motor specifications and know-how. I guess your best bet would be to contact the manufacturer and ask if they have or can point you to other controller options than the one with the push button you have now.

If it is a 3 wire stepper motor you'll run into similar issues and would need a proper driver...
 
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Thanks all for the replies and link. I wonder if something like this would work?
www.ebay.co.uk

5V-12V DC Brushless Driver Board Controller For 3/4 Wire Hard Drive Motor (L50) | eBay

Find many great new & used options and get the best deals for 5V-12V DC Brushless Driver Board Controller For 3/4 Wire Hard Drive Motor (L50) at the best online prices at eBay! Free delivery for many products.
www.ebay.co.uk
I do wonder if there's a universal colour coding for the U. V. W. wires as it must be imperative to get them in the correct sequence. I wouldn't want to cut the jack off only to find 3 black wires! The motor in the pump must be quite low capacity, current wise as the power unit only outputs 12V DC @ 1 Amp. At the end of the day, it's just an experiment that I may back out of but I've learned a lot already from the above advice. Maybe buy a small 12V BLDC motor with the above controller to play with.
cheers for now
Steve
 
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That might work... :) Maybe this helps.
or this
www.electroniclinic.com

Hard Disk Motor Speed Controller using Arduino, DIY Sander

Hard Disk Motor Speed Controller using Arduino, Diy Sander- In this tutorial, you will learn how to turn your old Hard Disk Drive Brushless DC motor
www.electroniclinic.com www.electroniclinic.com

I know that PC HDD also contains a 12 volts BLDC motor, having 3 or 4 wires, these you can take out and run on AC power regardless of the sequence you connect the wires. Simply hook 2 wires to a 12 Volts AC converter and it runs. The disadvantage is, like this without a driver the motor can not self start and needs a push. Thatá about it what I personally know about them. Never tried any of these things extensively.
 
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