Interfacing PIC microcontroller to a TRIAC for AC load control

Thread Starter

jean120

Joined Jan 24, 2016
75
I am using PIC16F1936 and want to control the speed of an AC single phase motor using the switch interfaced to a PIC via PORTA.
I have implemented a circuit for controlling the speed of an AC Single phase motor using the switch interfaced to a micro-controller where each of the four switch allows the PIC to create a delay which is referred to as a firing angle.
Here below is the circuit with the code I tested and found that they are ok as with simulation in proteus it is giving correct firing angles.Unfortunately physical implementation is not working at all.
 

jpanhalt

Joined Jan 18, 2008
11,087
Also, seeing the phase angle change is simulation may bot be a good representation of how your particular motor will respond.
1) What type of single phase motor is it?
2) Will a manual triac speed control, e.g., a light dimmer, work as you want?
3) Does "not working at all" mean the motor won't run regardless of the triac setting?

John
 

Thread Starter

jean120

Joined Jan 24, 2016
75
http://www.microchip.com/forums/m941365.aspx Yes the motor doesn`t work regardless of motor type.The motor I am using is the one of a fan requiring 230VAC at 50Hz and 1A.
it turn at a very low speed which can`t be adjusted even if the delay time fo the TRIAC is changed.
When a bulb is connected it flick,it turns on-off and so on it is not keeping stable with light variation.

see the circuit here
 

bertus

Joined Apr 5, 2008
22,266
Hello,

I still do not see any picture.
Are you using a zero crossing circuit for synchronisation with the AC?

Bertus
 

jpanhalt

Joined Jan 18, 2008
11,087
http://www.microchip.com/forums/m941365.aspx Yes the motor doesn`t work regardless of motor type.The motor I am using is the one of a fan requiring 230VAC at 50Hz and 1A.
it turn at a very low speed
which can`t be adjusted even if the delay time fo the TRIAC is changed.
You haven't quite addressed my question(s).

1) Can the motor you are trying control be controlled with a triac? That is a simple test. If it cannot be controlled with a triac, then adding a PIC to the equation won't change that fact.
2) New question: If the motor doesn't work as you wish when connected directly to the mains (i.e., it turns too slowly), it will not go faster when connected to the triac. Is that interpretation of the underlined comment correct?

John
 

Thread Starter

jean120

Joined Jan 24, 2016
75
I checked that one of Tahmid blog but it didn`t help a lot.
Are you advising that if I change those resistors the circuit should work?With AC Single Phase motor?

Regards,
 

Thread Starter

jean120

Joined Jan 24, 2016
75
I tried to place 150Ohm at the collector of that transistor controlling the MOC3020 but even when the PIC is not in the board the motor turns at maximum speed,so the PIC is no longer controlling the motor.Even with 180ohms the motor turns at maximum speed even when the PIC is not in the board.

Please help!!
 

nestbulala

Joined Dec 12, 2015
111
Jean,

Try this circuit I used for the fan motor of air conditioning unit. You just vary the delay from the PIC as per Tahmid Blogs and it should be running fine. It worked for me for 15 watt PG Motor.
 

Attachments

I designed a soft start circuit for an amplifier.
I just used a 390K resistor into a PIC input for mains zero crossing detection, worked great.
To drive the triac I used an opto coupler.
 

Thread Starter

jean120

Joined Jan 24, 2016
75
Dear nigelwright7557,could you share the circuit with me? You can send me a PM, thank you very much.


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