conveyor belt automation project-dc gear motor current

[goldriver]

The dilemma is that we have 12V,6A dc gear motor and an h bridge called tle6209 connected to arduino microcontroller. The tle6209 is 7A h-bridge,the motor coupled to the conveyor belt draws 2.33~2.5 from the powersupply when not connected to the controller and h-bridge ,and it has a direct connection to the powersupply ,the belt moves finely. But when we connect it to the controller and h-bridge ,the belt doesn't move. We are unable to figure out where the problem lies. Is our h-bridge the problem or the powersupply isn't giving enough current or the code,which isn't giving the logic inputs properly to the motor.

 

[BradtheRad]

It sounds as though you tested the motor with a separate 12V power supply. Do you mean to say it moves the conveyor in one direction at one polarity, and the opposite direction at the opposite polarity?

You must also test the H-bridge separately, whether it can power a plain 6A load, at either polarity. (I say 6A because it is stated in your first sentence, although you state the motor draws 1.35 - 1.5A elsewhere.)

Anyway the H-bridge must deliver 3 or 4 times the motor's normal draw. This is because a motor normally needs a current surge as it starts up.

A good way to test it is with a lamp that draws 6A at 12V, or a resistor with a value of 2 ohms, and a watt rating of 72W. (Perhaps the resistor can be a lower watt rating, since you probably will not leave it hooked up for such a long time that it gets overheated.)

An incandescent headlight bulb is a convenient load to use. Results are unambiguous of course.

If the plain load does not work, then you must measure voltage at the pins which deliver power to the load. You must verify that each pin can both provide current and sink current.

 

[D.A.(Tony)Stewart]

WIthout specs, my hunch is like others, your bridge is far too lightweight.

The rated current for motors is often only 25% of startup or stall current. This is determined by coil resistance and voltage.

Lightbulbs are similar except rated current is 10% of startup current.

So if the motor is rated at 6A I would have expected at least a 25A (peak) bridge. Double that again if you switch directions while moving at full speed..

Another way to look at is, what voltage is present if two Bridge MOSFETS are equal to the Coil resistance? Answer 50% Is that enough to start it? Should be as long as it doesn't over-heat. at VI power lost.

Normally you want a bridge RdsON to be <5% of coil resistance.

 

[goldriver]

I wanted to say that when you connect the belt's motor directly to the power supply ,the motor kicks into action and the belt starts moving. I have not tested it yet with opposite polarities but the belt demonstrates the above behavior when directly connected to the power supply without any h-bridge or microcontroller interface. On the other hand, if i connect it through an interface of h-bridge and a micrcontroller,the belt doesn't move and the motor makes this weird sound. My guess was that maybe the motor isn't getting enough current because the h-bridge is failing to provide the required current. I have uploaded some pics of my project and the motor which is responsible for actuating the belt. Check the links below

https://obrazki.elektroda.pl/8714833100_1402119837.jpg
https://obrazki.elektroda.pl/8382711200_1402119834.jpg

 

[goldriver]

Can you recommend any h-bridge? We are also having trouble interfacing the tle6209 ic with the arduino microcontroller as it requires serial communication between the uc and itself. Plus There is no tutorial or help available regarding this h-bridge.