Run 2 electro-motors for a long time

Hi

I want to run 2 DC electromotors for a long time. Since I do not have so much knowledge in electromotors and the drivers, I decided to ask here:

I want to run the DC motor for several days, probably without any stop (I want to run a pump for several days using them). I want to do it using the L298N driver and this electromotor:

http://www.ebay.com/itm/112097117371?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

https://www.aliexpress.com/item/Free-Shipping-1pcs-New-Dual-H-Bridge-DC-Stepper-Motor-Drive-Controller-Board-Module-L298N-for/32394160729.html

My questions are:

1- I am worried that will it work or will I gonna have some troubles with this setting?

2- Then, for running with the PWM, if I want to use a capacitor, which size of capacitor should I choose to smoothen the electromotor run? Is it really needed?

If you could answer this, I would be really grateful.

Best regards

Saeed

I can’t immediately see from your link what current the motor draws. It will be important to ensure that it is comfortably within the capacity of the driver - or else get a more powerful driver.

The L298 is old technology and rather inefficient. It will get hot in use. If you can find another driver that uses MOSFETs it will be much more efficient and operate at a lower temperature for the same current. have a look at the Pololu website.

Apart from those comments there is no reason why your system should not run until the motor bearings or the armature brushes wear out.

…R

The link shows current of .73A which is presumably at no load, nicely within its normal operation limit of 2A. It's silent on the stall (= startup) current. If you physically have these motors at hand, you can get that by measuring the resistance across the terminals.

Our friend Mr Ohm tells us I= 24/R. Then compare that to the L298's peak 100us burst current limit of 3A.

But as previous poster said, there are newer and nicer solutions. There's a reason for that huge heatsink ;)

You mentioned this is for a pump? If so do you need bidirectional control?

If you just want speed control of a single direction pump a single MOSFET and diode will do the job. Very efficiently. The circuit is quite simple.

alka: You mentioned this is for a pump? If so do you need bidirectional control?

If you just want speed control of a single direction pump a single MOSFET will do the job.

Good catch. I get a bit blinkered by robot thinking, which usually needs both ways.

And I meant to mention, the photo on the link shows a direction arrow. I don't know if that implies it's only supposed to go one way?

Hi Robin2, manor_royal and alka

Thank you very much for your answers.

Yes, I want one direction rotation of the electromotor with adjustable speed. So, based on your comments, I will use the MOSFET and that should be enough for me.

The thing that was making me vorried was the PWM, which is on-off voltage. As I noticed from Robin2's comment, it will not make any failur for the electromotor.

Then, I also observed that people are using capacitors with the electromotor which I also saw in training 12 of the original Arduino strater kit book. Since I may need to run the electromotor at low speed at some points, what kind of capacitor would suit this?

Best regards

Saeed

zeedo65:
The thing that was making me vorried was the PWM, which is on-off voltage. As I noticed from Robin2’s comment, it will not make any failur for the electromotor.

Then, I also observed that people are using capacitors with the electromotor which I also saw in training 12 of the original Arduino strater kit book. Since I may need to run the electromotor at low speed at some points, what kind of capacitor would suit this?

As long as you are using less than or equal to than the motors maximum voltage the PWM should not cause any damage.

Here is a generic single mosfet one direction driver,
motordrive.GIF

The 1000uf capacitor is for smoothing the voltage on the main power rail. It should be sized to keep the power supply voltage steady when a large fast current draw happens. ie. starting.

The 0.1 uf ceramic capacitor is across the motor coils and helps reduce voltage spikes and noise from the brushes contacting the commutator on the motor.

Each other component has its purpose in that circuit too, don’t leave anything out and if you aren’t sure why its on the schematic just ask.

Not sure what the motor actually is - what is this supposed to mean:

Permanent Magnetic Speed Reduce DC Motor

or

Material : Metal, Electronic Parts;Main Color : black, Silver Tone
Permanent magnetic cylindrical shape and 2 wires connectors.

Electronic parts?? Really?

Who knows.

The specs are nonsense - electrical power in = 17.5W, the nominal power is 7W out,
torque x speed suggests 9W output though.

You are getting a pig in a poke with this listing.

Robin2: The L298 is old technology and rather inefficient. It will get hot in use.

Indeed but at 24V is much less of a problem that 6V at least!

alka:
As long as you are using less than or equal to than the motors maximum voltage the PWM should not cause any damage.

Here is a generic single mosfet one direction driver,
motordrive.GIF

The 1000uf capacitor is for smoothing the voltage on the main power rail. It should be sized to keep the power supply voltage steady when a large fast current draw happens. ie. starting.

The 0.1 uf ceramic capacitor is across the motor coils and helps reduce voltage spikes and noise from the brushes contacting the commutator on the motor.

Each other component has its purpose in that circuit too, don’t leave anything out and if you aren’t sure why its on the schematic just ask.

Thank you very much alka, I will put exactly the same thing.

MarkT:
Not sure what the motor actually is - what is this supposed to mean:orElectronic parts?? Really?

Who knows.

The specs are nonsense - electrical power in = 17.5W, the nominal power is 7W out,
torque x speed suggests 9W output though.

You are getting a pig in a poke with this listing.

Hi MarkT

Yes, I know. :slight_smile: When you buy from these kind of sellers, there is always the possibility to have huge difference between what you want and what you get. I am just hopeful that the 3000 RPM is not 300. :smiley:

I hope it works out.

The l298n isn't terrible for this type of scenario providing the current isn't beyond its capabilities. That driver board you linked is so cheap and very easy to use and Mark is right about the l298's voltage drop being less of an issue at higher voltages.

I would probably buy one anyway at that price.. and build one too.

The circuit really wouldn't even need a board, you can solder resistors and wires to the legs of the MOSFETS and put the diode and small cap right across the motor terminals. Big cap across the power in.

Yes, I already ordered the L298N and they are here. I am waiting for the electromotors, which may take 1 month to arrive. Let’s see how it will work. :slight_smile:

Hi all

Luckily I have my motors here after a while. So, I checked it with the L298N and it works fine. It does not warm up with my settings and that is the good news for me.

alka: I hope it works out.

The l298n isn't terrible for this type of scenario providing the current isn't beyond its capabilities. That driver board you linked is so cheap and very easy to use and Mark is right about the l298's voltage drop being less of an issue at higher voltages.

I would probably buy one anyway at that price.. and build one too.

The circuit really wouldn't even need a board, you can solder resistors and wires to the legs of the MOSFETS and put the diode and small cap right across the motor terminals. Big cap across the power in.

Now, the question is: Does this board have the capacitors and the diode included in the board or is it better that I add them there to smoothen the electromotor? I see that it has 2 capacitors, but is it for the same purpose?

Best regards Zeedo65

Looking at the module it seems there are four diodes on either side of the l298 chip. They also have 220uf electrolytic caps on the power input so you don't either of those.

the 0.1uf cap across the motor coils is a good idea for the cost of it. It can reduce the electrical noise from the motor substantially.

And the 0.1uF cap goes on the motor terminals directly, it won't do anything remote from the motor. If the motor has flying leads you really have to solder the cap inside the motor where the leads attach, if feasible. Use twisted pair for the wires to the motor.