Speed Control of single phase induction motor using TRIAC

[Newbie]

I got a mini project to design the speed control of 1 phase induction
motor using TRIAC. I googled a lot for it but all in vain. I need the
specifications of the components to be used and the circuit diagram.
Kindly guide me how to proceed.

 

[Don Lancaster]

I got a mini project to design the speed control of 1 phase induction
motor using TRIAC. I googled a lot for it but all in vain. I need the
specifications of the components to be used and the circuit diagram.
Kindly guide me how to proceed.

Speed control of an induction motor is enormously difficult unless you
use the latest chips in a complex circuit.

Single phase is MUCH worse than three phase as well, owing to starting
considerations.

The project is by no means trivial. At the very least, a full H bridge
drive will likely be needed.

To properly control the speed of an induction motor, you have to change
BOTH the voltage AND the frequency.

See http://www.tinaja.com/magsn01.asp


--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com

 

[Homer J Simpson]

I got a mini project to design the speed control of 1 phase induction
motor using TRIAC. I googled a lot for it but all in vain. I need the
specifications of the components to be used and the circuit diagram.
Kindly guide me how to proceed.

First make sure the motor is a PSC motor.

 

[Spehro Pefhany]

I got a mini project to design the speed control of 1 phase induction
motor using TRIAC. I googled a lot for it but all in vain. I need the
specifications of the components to be used and the circuit diagram.
Kindly guide me how to proceed.

If you just need limited speed (eg. 2:1) control of a shaded-pole or
PSC AC induction motor with a fan-type load (drag with little
friction) the problem is trivial.


Best regards,
Spehro Pefhany

 

[default]

I got a mini project to design the speed control of 1 phase induction
motor using TRIAC. I googled a lot for it but all in vain. I need the
specifications of the components to be used and the circuit diagram.
Kindly guide me how to proceed.

Specify the type of motor, speed range desired and the application.

A small 1/20 hp shaded pole motor driving a light load like a fan
would be a candidate for a simple triac control.

A 1 hp motor driving a large fan or heavy load would be a candidate
for a variable frequency drive or a mechanical speed adjuster

Big difference in complexity. There might be some specialized IC's
to make a VFD simple since there is a lot of call for it. When going
to a VFD for speed control, there's a lot of incentive to use three
phase because capacitor run/start motors don't take kindly to
different frequencies and 3 ph does.

 

[Newbie]

Thanks everybody for the help. Actually the project has been assigned
to me by a very strict instructor of mine, so I can't tell her that
its trivial or very hard etc etc. Also nothing else has been
specified. As far as I understand I have to use TRIACs to design a
variable voltage/frequency source, but thats the only thing I know.
Can anyone suggest me a site or something from where I can get atleast
a circuit diagram or the components to be used to design such a
circuit.

 

[Rich Grise]

Thanks everybody for the help. Actually the project has been assigned
to me by a very strict instructor of mine, so I can't tell her that
its trivial or very hard etc etc. Also nothing else has been
specified. As far as I understand I have to use TRIACs to design a
variable voltage/frequency source, but thats the only thing I know.
Can anyone suggest me a site or something from where I can get atleast
a circuit diagram or the components to be used to design such a
circuit.

No, you're supposed to use your textbooks and the library to figure it
out for yourself.

That's why it's called "school". There isn't anybody to spoon-feed you
the answers when you get out in real life.

Good Luck!
Rich

 

[Homer J Simpson]

Thanks everybody for the help. Actually the project has been assigned
to me by a very strict instructor of mine, so I can't tell her that
its trivial or very hard etc etc. Also nothing else has been
specified. As far as I understand I have to use TRIACs to design a
variable voltage/frequency source, but thats the only thing I know.
Can anyone suggest me a site or something from where I can get atleast
a circuit diagram or the components to be used to design such a
circuit.

Look up PSC motors and speed control. You don't need variable frequency and
it won't help.

 

[Mark Harriss]

Thanks everybody for the help. Actually the project has been assigned
to me by a very strict instructor of mine, so I can't tell her that
its trivial or very hard etc etc. Also nothing else has been
specified. As far as I understand I have to use TRIACs to design a
variable voltage/frequency source, but thats the only thing I know.
Can anyone suggest me a site or something from where I can get atleast
a circuit diagram or the components to be used to design such a
circuit.

There's a basic treatment of the topic in a ST Micro applications note
where they cover several triac topologies and problems they may have.

http://www.st.com/stonline/products/literature/an/3566.pdf

 

[Newbie]

No, you're supposed to use your textbooks and the library to figure it
out for yourself.

That's why it's called "school". There isn't anybody to spoon-feed you
the answers when you get out in real life.

Good Luck!
Rich

Thanks for the suggestion Rich but let me tell you that I wasn't
demanding to be spoon fed. I was just asking for the right place to
start with. Morever I had googled a lot before asking the question in
this forum.

 

[Newbie]

There's a basic treatment of the topic in a ST Micro applications note
where they cover several triac topologies and problems they may have.

http://www.st.com/stonline/products/literature/an/3566.pdf

Thanks Mark, the document really helped me. That was the thing which I
needed. Lots and lots of thanks again.

 

[Mark Harriss]

Thanks Mark, the document really helped me. That was the thing which I
needed. Lots and lots of thanks again.

Also take a look at some thyristor triac scr databooks circa 1970's in
your campus library if they have any, the application notes should have
something.

 

[Homer J Simpson]

Also take a look at some thyristor triac scr databooks circa 1970's in
your campus library if they have any, the application notes should have
something.

The old GE SCR handbook and hobby book could be useful.