period_skip

motor speed control by skipping periods of AC mains

Author Eur van Andel, eur@fiwihex.nl © 2009
Adapted-by
Compiler >=2.4g

Description

AC induction motors are low-priced, very reliable and widely available.
This library provides a way to control the speed of these motors, if they have reasonably
angular momentum.



Explanation: this is *NOT* phase control: http://en.wikipedia.org/wiki/Phase_control
Phase control makes a lot of noise, both audible and electrical. 



This is deliberate skipping of half-waves. There are only 100 half-waves per second
@ 50 Hz and bit-fine control of motor speed would result in long duty cycles (2.55s)
with varying motor speeds and audible pitch change. 
So we keep the period cycle at 32 half waves, with 8 duty cycles that only differ 
one half-wave to minimise audible noise. 
Electrical noise is minimized by zero-voltage switching.


Sources

Fairchild Application Note AN-3004, http://www.fairchildsemi.com/an/AN/AN-3004.pdf
http://www.sullivan-county.com/ele/triacs2.htm for schematics and examples how 
to generate a zero-crossing signal. 


Dependencies

No dependency found



Summary

Global variables/contants

Procedures

Functions


API details

Global variables/contants

Procedures

Functions


Related samples

Here are the list of samples which use this library:

16f87716f877_period_skip.jal