temperature sensor (LM35) + PIC16f877 + ac motor

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delifadzli
Posts: 4
Joined: 13 Feb 2010 05:47

temperature sensor (LM35) + PIC16f877 + ac motor

#1 Post by delifadzli » 13 Feb 2010 05:55

hi everyone,,

i want to ask for a guidance for my project . The project basically use Temperature sensor (LM35) as input , PIC as "analyze" item and ac motor (output-speed change)..

here the problem is regarding 2 things

1. ADC problem-- LM35 interface pic
-either use PWM or sampling

2.the big one- how to interface PIC 16f877 and ac motor--can provide some code or diagramm..just for the guidance..

to be truth... i quite new in this area (microcontroller)....someone please...

wait for ur respond....

dariush_abbasi
Posts: 120
Joined: 11 May 2008 18:47

Re: temperature sensor (LM35) + PIC16f877 + ac motor

#2 Post by dariush_abbasi » 14 Feb 2010 22:01

Hi,
I don't know whether helps or not but...
There is a sample code for PIC and LM35 in the book called "ADVANCED PIC MICROCONTROLLER PROJECTS IN C".
I think that would be a good start.
Be successful.

delifadzli
Posts: 4
Joined: 13 Feb 2010 05:47

Re: temperature sensor (LM35) + PIC16f877 + ac motor

#3 Post by delifadzli » 15 Feb 2010 04:56

thanks for the info..really hope it function well for the project...

by the way, how about the interface with ac induction motor.. isn't been conclude in the book??

i hope for Ur opinion about that...

waiting for respond....

dariush_abbasi
Posts: 120
Joined: 11 May 2008 18:47

Re: temperature sensor (LM35) + PIC16f877 + ac motor

#4 Post by dariush_abbasi » 15 Feb 2010 08:49

Hi,
No,not about motor,just for LM35 but the good point is the program is for Mikroc.
Be successful.

delifadzli
Posts: 4
Joined: 13 Feb 2010 05:47

Re: temperature sensor (LM35) + PIC16f877 + ac motor

#5 Post by delifadzli » 23 Feb 2010 17:26

i am really blur and confused right know...can anyone tell me on how to interface the PIC16f877 with ac induction motor ( speed)...--ceiling fan...

guide me please....

urgent...

Radu86
Posts: 47
Joined: 11 Jan 2010 17:10
Location: Romania, Iasi

Re: temperature sensor (LM35) + PIC16f877 + ac motor

#6 Post by Radu86 » 23 Feb 2010 18:33

I don't know for sure, but I think one way to control the speed of the motor is to use the PIC as a frequency converter. That means you have to recreate the sinusoidal voltage at different frequencies. As for this I do not have any code nor I have any idea where you could find something to help you.

Is the ac motor a 3 phase motor? If by construction it gives you access at the rotor's coils you can change the speed by adding resistors like in this link: http://em.ucv.ro/elee/ro/realisations/m ... igure6.jpg

If it is not a 3 phase motor (you say it is a fan motor) than i guess the first part is the way to go.

delifadzli
Posts: 4
Joined: 13 Feb 2010 05:47

Re: temperature sensor (LM35) + PIC16f877 + ac motor

#7 Post by delifadzli » 23 Feb 2010 18:49

thanks for the reply

eventually, this project used the ceiling fan motor-single phase motor...

can u suggest something...?

totally need help...

Radu86
Posts: 47
Joined: 11 Jan 2010 17:10
Location: Romania, Iasi

Re: temperature sensor (LM35) + PIC16f877 + ac motor

#8 Post by Radu86 » 24 Feb 2010 10:43

I've done a little reading and I have an idea. These motors can be controlled through variable voltage and fixed frequency or fixed voltage variable frequency.
I think it is easier to variate the voltage. You can use the PIC as a chopper. I believe the technique is called PWM-Pulse With Modulation. Of course you will need other components in order to support the motor's current and voltage. I haven't tried this yet so I don't really now how it works or if it works, but in theory does :). The idea is to give pulses to a switch (relay transistor or anything that can act like a switch) in order to control an analog device (your motor in this case). the pulse is given by setting a pin to 1 and 0 at a chosen time rate. if you want these pulses to be faster you simply choose a shorter time rate.
create a few procedures and test them until you get the pulsing time you want.
For how to connect this to the motor I think there are a lot of methods on the internet.

Here: http://www.freescale.com/files/microcon ... AN3471.pdf is a solution using PWM for a ceiling fan.
Hope it helps.

jennyfan
Posts: 1
Joined: 27 Mar 2010 16:23

Re: temperature sensor (LM35) + PIC16f877 + ac motor

#9 Post by jennyfan » 27 Mar 2010 17:48

The LM35 could give more output power or voltage in your ceiling fan motor. Anyway, it should be better that the thermocouples.

cath_3105
Posts: 1
Joined: 23 Oct 2010 09:17

Re: temperature sensor (LM35) + PIC16f877 + ac motor

#10 Post by cath_3105 » 23 Oct 2010 09:43

Our neighbor are doing electric fan repair. I heard that they also use LM35. As they said, LM35 gives more output voltage. It is the same with jennyfan.

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