[PIC] how to control the stepper motor of the electronic expansion valve using pic16f877 uC

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Prabhu Siva

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Hello guys i am new to this forum. i need a help to control the stepper motor of electronic expansion valve.

it has four coils and one common line

i need to open this valve for some period of time and remain closed for some period of time

i trying to use pic 16f877a controller and using pic ccs compiler to program it.
 
Last edited by a moderator:

Frankly, the link to the Youtube video was worthless and has been removed.

Forget about posting video links, what is needed is the actual datasheet for the electronic valve.

Also, post a schematic and the code you have already written, so that we may examine it.


BigDog
 

It's very precision work. It's working proceeder depend on application.
I familiar with refrigeration expansion valves for controlling the refrigerant flow by controlling the opening degree of a expansion valve via pressure transmitter analog input.

1. Where are you using this?
2. What type of motor is inside the valve?
3. What will be steps when you open/close it?
 



1.I am using this expansion value to control the refrigerant flow
2. It is a four coil stepper motor it has A,B,A",B" coils
3.To know how its work goto in youtube type hvac expansion value you can see the entire operation

you can also refer the datasheet .i cant upload any documents in the form

- - - Updated - - -

I plan to control this stepper motor by adding shift register in between the pic16f 877a and stepper motor. if the particular temperature value is less than the set temperature i need to closed the value and vice versa.

but making the stepper motor to run front and back to open and close
 

Prabhu Siva said:
3.To know how its work goto in youtube type hvac expansion value you can see the entire operation
Click to expand...

The original video, to which you previously posted the link, does not discuss the specs of the valve, it's only an advertisement for a training company.

Prabhu Siva said:
you can also refer the datasheet .i cant upload any documents in the form
Click to expand...

What datasheet? And why can't you upload documents to this forum?

Either post a link to the datasheet or I will delete this thread as spam advertisement.


BigDog
 


If you've never done this before, I would recommend you to head for specialized integrated circuits like the DRV8825.
It's the best way to have smooth motion, and avoid doing any damage to the motor. Moreover, the current limiting feature let you use higher voltages than the steeper would carry to increase its maximal speed (by increasing the current rising speed).
All you'll have to do with your microcontroller, is to output one direction signal, and one step impulse signal (one impulsion equals one step, or less with the microstepping feature)
Drawback (or not): SMD circuit, if it's a problem, look at pololu stepsticks ;-)
Hope this helps.
 

This is a brochure not a datasheet, there are no electric specs in it for the stepper motor.
Click to expand...
And it describes more than one expansion valve type. The lessest you should do is to tell the exact type number of your valve.
 

Ms. Prabhu siva

I am danfoss EL business partner. So I attention to you that these valves are not designed for only temperature controlling. These ETS 6-xx and ETS 12.5-400 control superheat of refrigerant also and control with danfoss dedicated controllers EKD316. So I suggest to you if you making it only for temperature controlling read carefully it,s mechanical structure. Because if you will in mistake will not get the desire temperature. Your compressor will run unnecessarily and useless power lose.
Even after that I want to tell you that these valves control in micro steps. The number of steps and steps/sec also will be set in your controller. See EKD-316 datasheet parameter n37, n38 for stepping.

See it's dedicated control datasheet
**broken link removed**
 

ETS6 stepper motor data can be found in the datasheet, it's a 12V unipolar stepper.

**broken link removed**
 

Actually i need to control the flow of super heat refrigerant. and i attached the low pressure switch in front of the compressor and i placed a high pressure switch in outlet of the compressor based on the input of these pressure switch i need to control the refrigerant flow.
 

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