Hi!

I am working on a university project. We are building a vehicle similiar to the BattleBots competition.
Everything is working well but I have a problem with a 12 VDC motor controlled with transistor/MOSFET.

I am using this motor water pump: https://www.twinschip.com/Mini_Water Pump_12V4.8W_240L_H

I tried using it with regulated laboratory source, it's working well between 6 and 12 Volts.
I created a basic MOSFET circuit and later a NPN Transistor circuit with Arduino (as in attachment), which would control the voltage to the pump.
These circuits work with all DC motors that I have, but not with the water pump one.
I know it says its brushless but I don't believe it as the motor has only 2 wires and the power can be controled with the voltage from the laboratory source.

Can anyone help how to control the power of the pump with arduino? What should I do?


Thank you for your help.

Lukas

 

It could well be BLDC (brushless), for example PC fans are brushless and only have two conductors, the use an internal detector IC and also do the switching internal.
In the exploded view, it shows no brushes. i.e. Brushless.
Are you using BLDC to control the pump or just ON/OFF with the Mosfet etc.?

 

Can anyone help how to control the power of the pump with arduino? What should I do?

What transistor or mosfet # are you using?

 

It does seem to be a brushless since not only does it say so, but there is also this:

​

 

It does seem to be a brushless since not only does it say so, but there is also this:

View attachment 307617​

The exploded view shows it clearly.

 

Thank you all for fast replies. So probably it is a brushless motor. Can you help how to control the power of it with arduino?
I tried using the following:

• Adafruit TB6612 motor driver
• MOSFET IRB4410
• NPN transistor TIP120

None of them worked unfortunately.

Thank you for your time.

 

Do you want ON/OFF or PWM pulsing, RPM control??

 

Do you want ON/OFF or PWM pulsing, RPM control??

I would like to have RPM control.

 

Probably not possible with that motor then.

 

Probably not possible with that motor then.

I would like to control it as I can do that with the laboratory power source. With that I can change the voltage continuously from 5 to 12 V and the motor works and is changing the RPMs.

Can I achieve this somehow with Arduino?

 

Probably will need a method using a variable voltage rather than switching, using PWM e.g. etc.
There are many other cheap DC motors that could do the job.

 

The motor absolutely is a brushless version. If the speed command is a duty cycle then use a filter capacitor to smooth the pulses into a constant voltage. That may take a fair size electrolytic capacitor.

 

If the speed command is a duty cycle then use a filter capacitor to smooth the pulses into a constant voltage.

This works converting the Arduino PWM output to a DC voltage and using IC1 to drive Q1 in a linear mode. There will be a max output of only appx 11.3 volts with a 12 volt supply. Q1 will require a heat sink.

 

How far I see, the moror is kW mighty, thus the currents is no much less than 100A, therefore thermal loss on the junction will be at least 6 V*100A=600W what is damn much to be able to cool. With MOSFET it eases but not so much, for example 50 miliOhm*100A^2=500W. The only realistic way out is PWM where thermal power may be reduced dramatically.

The second inability source is Arduino having few mA of output current. The same time 100 A harvesting in paralelled 2N3055 at beta=20 demands at least 5A of base current or larger. Thene imminently must be applied the current booster between Arduino and output booster.

 

How far I see, the motor is kW mighty, thus the currents is no much less than 100A,

Motor is rated 12 volt at 400ma.

 

The whole motor body is only 50mm long !!

 

It seems that Janis is thinking about a different motor. The unique brushless motor is indeed 4.8 watts and 12 volts. So not sure where the 100 amp motor comes in. Possibly cranking the big V8 engine on that battlebot, maybe???

 

Yepp, with a motor I visualize the timber sawmill or etc.
For small fingertip sized motors even BC548 is good enough.

 

Not much duty cycle control headroom if using Arduino PWM.
Avg current must be about 333ma to start the fan, so DC must operate at approx 85-90% with available Arduino PWM frequencies.

 

,DC must operate at approx 85-90% with available Arduino PWM frequencies.

The circuit posted in #13 was tested on a 3.3 volt 200hz signal with a duty cycle of appx 90% at 11.3 volts and appx 10% at 5 volts out.
Isn't the Arduino capable of that ?