Synth-DIY Yahoo! Groups Archives

Re: [AVR-Chat] Re: PWM Help

2008-02-04 by np np

If its mains motor is is probably better controlled by a PID algorithm and using the mains cycles to phase control the power.

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----- Original Message ----
From: Zack Widup <w9sz@prairienet.org>
To: AVR-Chat@yahoogroups.com
Sent: Monday, 4 February, 2008 2:17:20 PM
Subject: Re: [AVR-Chat] Re: PWM Help

What kind of motor are you trying to control? Synchronous AC motors do 
not work by PWM. Stepper motors like the kind used in satellite dish 
feed polarotors use PWM. Other steppers require a set of phased pulses 
which vary the pulse frequency to control the speed. Regular DC motors 
can be controlled in a variety of ways.

Zack

On Mon, 4 Feb 2008, ktal3at wrote:

> I am controlling the motors by using avr micro control
>
> the way to increase or decrease the motor speed is the PWM
>
> and it is my first time to control motors
>
> so i am looking for help how to use the PWM and how can i connect the
> motors to controller
>
> i know that i must use h-bridge or relay (( i'm using h-bridge))
>
> thanks
>
>
>
>

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Re: [AVR-Chat] Re: PWM Help

2008-02-04 by Tom

np np wrote:
>
> If its mains motor is is probably better controlled by a PID algorithm 
> and using the mains cycles to phase control the power.
>
   Not necessarily.  PID yes, V/F control works quite well for AC 
induction motors, and is inexpensive and easy top do.  Space Vector PWQM 
is even better, is you're using three phase induction motors.   One snag 
with V/F control is that it will only achive approximately 83-86% of the 
maximum rated speed for the motorm due to the fundamental mathematics 
invovled (and no, *I* don't understand the reasons thoroughly, the mathj 
is extensive)


avrFreak

Re: PWM Help

2008-02-06 by Joe

Here is some starting help:
I did a pwm thermal controller. I used a TEC (thermo electric cooler) 
that I controlled with PWM thru an IRF530 fet. I also used a Dallas 1 
wire temp probe for feedback. I used a PID loop for temp regulation.
See:
http://tech.groups.yahoo.com/group/Meade_DSI/files/dsi%20cooling/
this should get you started.

JoeT