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#129453 - 03/25/05 07:26 AM confuse about a single-phase ac induction motor
wancoz Offline
Junior Member

Registered: 03/24/05
Posts: 3
Loc: jakarta barat, dki jakarta, in...
i need help. i'm trying to control a single phase ac induction motor (1/3 hp) with a microcontroller (i use AT89S52 from ATMEL). but i don't how to combine it (the motor n the microcontroller). Is there any circuit or driver or divices to control it. i use the motor to pull something heavy, so i must decrease the speed but still have the torque.

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#129454 - 03/27/05 06:33 AM Re: confuse about a single-phase ac induction motor
Dnkldorf Offline
Member

Registered: 12/12/04
Posts: 1091
Loc: nowhere usa
I am not familiar with that type controller, but I have instead installed gear reducers on motors to accomplish what you are trying to do.

However, I have no clue to what your application is here, so I just threw that out there.


Dnk..

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#129455 - 03/27/05 04:48 PM Re: confuse about a single-phase ac induction motor
Scott35 Offline

Broom Pusher and
Member

Registered: 10/19/00
Posts: 2724
Loc: Anaheim, CA. USA
wancoz;

If the Motor planned to be Speed Controlled is a Split Phase Induction Type (single phase Motor with a "Start Switch and Winding"), this should not be attempted.

Reason being that the Start Switch will engage the Start Winding at speeds of Apx. 80% (and lower) of the Motor's Full Speed.
When this occurs, the Start Winding remains active in the Circuit until the Switch re-opens.
The Auxiliary (Start) Winding draws a high level of Current, and if kept active for an extended period of time (like more than 30 Seconds), chances are the Winding will fry, the Breaker / Overload unit will trip, or both will occur.

If the Motor is a PSC (Permanent Split Capacitor) type, or a Shaded Pole type Induction Motor, then these may be Speed Controlled without damaging the Auxiliary Winding.

Just some FYI!

Scott35
_________________________
Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

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#129456 - 03/30/05 01:13 AM Re: confuse about a single-phase ac induction motor
wancoz Offline
Junior Member

Registered: 03/24/05
Posts: 3
Loc: jakarta barat, dki jakarta, in...
i don't know much about this motor. my teacher just gave me it, n want me to learn about it. he can't help me, coz he don't know much either...(shame on him) so, i'm trying to ask everyone who know more about the motor.

There is something written in the front of motor :

SPLIT PHASE START SINGLE PHASE INDUCTION MOTOR 1/3 HP (0.25 kW) 4 POLE
HZ 50 50 60
V 220 230 220
A 2.4 2.5 2.2
rpm 1420 1420 1720
JIS C 4004 JP20 JC0
frame b71
rating cont
ins class E
amb temp 30 celcius
bearing 6202ZZ
serial

i want to control the speed n the torque of the motor, but i don't know how.

The scheme is like this:

motor <--- driver(?) <--- AT89S52

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#129457 - 03/30/05 05:35 PM Re: confuse about a single-phase ac induction motor
Paulusgnome Offline
Member

Registered: 06/15/04
Posts: 56
Loc: Christchurch, New Zealand
What you are trying to do is not impossible, but is a big ask.
Firstly, your motor is not really the best for speed control because of the starting problems that someone posted about earlier. Not insurmountable, but tricky.
Second, you have to work out how to program the micro to synthesise a variable-frequency ac waveform, and to adjust this waveform according to what the motor is doing vs what you want it to be doing. You will also need interface circuitry to convert the low-level signal from the micro to the higher current and voltage needed to drive the motor.

If all the above seems like a real handful thats because it is. In my work as an electrical engineer I have looked at a similar problem and quickly came to the conclusion that a 3-phase motor and VFD provided the best solution. There are drives avaiable for some single-phase induction motors, but they are very picky about which motors they will drive, and split-phase motors are not one of them.

Later,
Paulus
_________________________
Mark aka Paulus

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#129458 - 03/30/05 05:47 PM Re: confuse about a single-phase ac induction motor
Scott35 Offline

Broom Pusher and
Member

Registered: 10/19/00
Posts: 2724
Loc: Anaheim, CA. USA
wancoz:

The description text you have provided, points towards the type of 1 Phase Induction Motor I was referring to (the type which should not have low speed control methods applied, due to start switch engaging).

 Quote:

There is something written in the front of motor :


From the description, the Motor sounds like this:

 Quote:

SPLIT PHASE START SINGLE PHASE INDUCTION MOTOR


Split Phase Start" refers to this Motor having an Auxiliary "Start" Winding, used to - of course - Start the Motor.
It is needed to Start the Motor's Rotor from a dead Stop (or turning less RPMs than apx. 80% of the rated speed...more on this to follow).

The "Split Phase" is an additional Motor Winding, which is designed:


    [*] At an "Offset" - in "X" number of degrees (like 20° to 60°) from the "Relative Polarity" of the Main "Run" Winding, in order to reduce the stationary Field of the Main Winding,

    [*] The Winding arrangements resemble an Open Delta Polyphase connection scheme - where one of the Windings; the "Start" Winding, is controlled by a Normally Closed Centrifugal Switch,

    [*] The Auxiliary "Start" Winding will have a lower Resistance/Reactance value than the Main "Run" Winding.


The term "Single Phase Induction Motor" refers to the design characteristics being a 1Ø Motor (not a Polyphase Motor - like 2 or 3 Phase), and it is an "Induction-type" Motor - AKA "Squirrel Cage Rotor" type Motor.
This Motor does not have a Wound Rotor (akin to the Armature of a DC Motor), and no input current flows DIRECTLY through the Rotor.
Current is Induced into the Rotor by introducing AC Power to the Stator Windings ("Stator Windings" are akin to the Field Windings of a DC motor).
These Motors function more similar to how a Transformer does, than how the typical DC Motor functions.

1Ø Induction Motors (with exception to a few special types) require a method of getting the rotor to spin from either a dead stop (AKA "Locked Rotor"), or to bring it upto "Near Synchronous Speed".
Polyphase (2Ø, 3Ø) Motors do not require auxiliary start methods, they have "self-starting" abilities.
This is due to the fact that the magnetic fields developed at the Stator Windings, are "Rotating", and therefore will reduce the field level of an adjacent Winding - causing the Rotor to rotate according to this "Imbalance".

 Quote:

1/3 HP (0.25 kW) 4 POLE


"1/3 HP" = one-third Horsepower; this is a "Fractional Horsepower" Motor.

"(0.25 kW)" = True Power rating for full load scenario. This is a 250 Watt (or 0.25 kiloWatt) rating.

"4 Pole" = there are two separate Stator Winding pairs, which will result in a Rotor Speed of 1/2 the Synchronous Frequency (not including the "Slip").
Example:
If the Synchronous Frequency of the AC Power System is 60 Hz, the equivalent RPMs (Revolutions Per Minute) would be:
3,600 RPMs
(60 Hz × 60 Seconds = 3,600 RPMs)

The "Unloaded" speed of a 2-Pole Induction Motor connected to 60 Hz is 3,600 RPMs.
As the Motor is loaded down (doing work), the rotor's speed "Slips" behind the Synchronous Frequency, until the maximum power is exceeded - then it stalls.
Typical Full-Load speed of a 2-Pole Motor is 3,450 RPMs.

Your Motor has 2 sets of "Pole Pairs", and is known as a 4-Pole Motor.
This, in effect, results in a speed, which is a fraction of the Synchronous Frequency (in this case - 1/2, or 50% Sync. Hz).

The "Unloaded" speed is 1,800 RPMs at 60 Hz, with a full-load slip frequency speed of 1,725 RPMs at 60 Hz (typ.).

 Quote:

HZ 50 50 60
V 220 230 220
A 2.4 2.5 2.2


"HZ 50 50 60":
This refers to the AC Power System(s) Synchronous Frequency, which the Motor is designed to operate properly with.
There are two "50 Hz" ratings listed, and one "60 Hz" rating listed.
These are setup in a way to correspond with the Full-Load Amperes (FLA) VS System's Nominal Rated Voltage.

"V 220 230 220":
These are the Voltage Ratings per Hz.

"A 2.4 2.5 2.2":
These are the FLA ratings per System Voltage - which is also per System Hz.

This Motor may be used on a 50 Hz AC System - at Voltages of either 220 VAC or 230 VAC; or it may be used on a 60 Hz AC System - at a Voltage of 220 VAC.

 Quote:

rpm 1420 1420 1720


Rotor Full-Load speed per Hz:
1420 = Speed at 50 Hz,
1720 = Speed at 60 Hz.


 Quote:

JIS C 4004 JP20 JC0
frame b71
bearing 6202ZZ


Typical Manufacturing data (the "Frame" type may be referenced in the NEC).


 Quote:

rating cont


Motor is rated for continuous use (3 hours or more of full-load operation)

 Quote:

ins class E


Insulation Class (winding Insulation) = "E"

 Quote:

amb temp 30 celcius


Ambient Temperature rating = 30°C (temperature of surroundings during normal operation)

 Quote:

serial


This should have the Motor's Serial Number following the word "Serial"

Per the application questions:


 Quote:

i want to control the speed n the torque of the motor, but i don't know how.


You could make this motor run at a higher speed (by increasing the frequency applied to it), but slowing it down will bring the start winding into operation.
Prolonged operation at lower than 80% synch. speeds, with a load applied, will damage the Motor's start winding.
This will result in a large volume of smoke leaking out of the Motor

 Quote:

The scheme is like this:
motor <--- driver(?) <--- AT89S52


That looks correct.
The "Driver" would be whatever amplification device you plan to use. Bring the AC Power into the "Driver" section, then run your Controller (Pspice / Pbasic stamps???) from a transformer tapped off the supply.

You could use this setup on this Motor for a simple Start-Stop operation, just not any speed control.
It may also be incorporated with other basic functions - such as "Forward/Reverse" control (requires leads to motor windings run from "Driver" section), or "Dynamic Braking" in either direction (or combine them all).

If you can obtain a Shaded Pole, Permanent Split Capacitor (PSC), or "Universal" (Brush/Commutator-Armature) type Motor, then you may apply Speed Control + directional + braking control to the Motor (with exeption to the shaded pole type - directional is fixed via shading pole, plus braking may not be functional).

 Quote:

i don't know much about this motor. my teacher just gave me it, n want me to learn about it. he can't help me, coz he don't know much either...(shame on him) so, i'm trying to ask everyone who know more about the motor.


Sorry to hear this about your instructor, but hopefully we can assist you to understand the basic operations and constraints of the AC Induction Motor.

Good luck!

Scott35

BTW, check out the Technical Reference section for Schematics of AC Induction Motors.
Do a search in the "Menu", search the links, or let us know if you cannot find the drawings, and I will post links.
_________________________
Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

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#129459 - 03/31/05 04:43 AM Re: confuse about a single-phase ac induction motor
Dnkldorf Offline
Member

Registered: 12/12/04
Posts: 1091
Loc: nowhere usa
Damn this guy "scotts35" is good.

However, I am still stuck on your application.


Do you need to change the speed up and down constantly?
Or are you just trying to slow the motor down to a constant lower speed?

Ex. The motor will spin at approx. 1700 revolutions per minute "RPM". Do you need to cut this in half, to say 800 RPM? 400 RPM?

Or do you need to control the motor speed to go slower when you want and then faster when you want? "On demand kinda thing".

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#129460 - 04/01/05 06:31 AM Re: confuse about a single-phase ac induction motor
wancoz Offline
Junior Member

Registered: 03/24/05
Posts: 3
Loc: jakarta barat, dki jakarta, in...
thank u very much for the answer scotts35, paulusgnome, and Dnkldorf...
but there something i forgot 2 tell 'bout what i wanna do with the motor...

like u (Dnkldorf) asked about the speed, i just wanna change the speed down (the lowest speed that motor can) constantly, coz it's too fast to pull something. can i do that with the motor???

my friend told me there's another way to decrease the speed, i can use additional gear (gear ratio) with the motor. is that right??? but, i'm trying to find if there is any device/circuit can decrease the speed on the motor.

i got a schematic to combine microcontroller i use (AT89s52) n the motor, but it can decrease the speed, just start the motor. i wanna ask about my schematic, but how to post it???


thanks before...

wancoz

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#129461 - 04/03/05 02:10 PM Re: confuse about a single-phase ac induction motor
Scott35 Offline

Broom Pusher and
Member

Registered: 10/19/00
Posts: 2724
Loc: Anaheim, CA. USA
wancoz;

 Quote:

i got a schematic to combine microcontroller i use (AT89s52) n the motor, but it can decrease the speed, just start the motor. i wanna ask about my schematic, but how to post it???


Just send (e-mail) the Schematic to me, or contact the Webmaster of ECN and make arrangements with the site's Admin. to send and post the Schematic.

Scott35

BTW, if sending to me, it may be a Raster image in .GIF or .JPG format, or may be an AutoCAD .DWG format - in Release 14 version.
_________________________
Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

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#129462 - 04/03/05 04:47 PM Re: confuse about a single-phase ac induction motor
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
wancozs,
I'd be rather careful about slowing a heavily loaded motor down too far.
The armature still needs to create enough air movement to keep the rotor and stator windings cool.
This has send more than a few perfectly good motors to the junkyard, prematurely.

Good Lord Scott,
If THAT isn't a post and a half, I don't know what is!.

[This message has been edited by Trumpy (edited 04-03-2005).]
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

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