Anyone tried making a VFD with a prop ??

Igor_RastIgor_Rast Posts: 357
edited 2012-10-16 - 23:58:38 in Propeller 1
Hello Fellow Forum Members

I am currently busy with a project that I started about 2 years ago , Building a climate controller to control the environment fully automated.
In my quest to find a microcontroller to do it all for me I remembered that I followed a class long ago about microcontrollers , and we used the basic stamp to get to understand how they work, doing the famous blinking led etc.

Googling around, and remembering the simplicity of programing with the basic stamp, Parallax was the first search. After finding out that the Propeller chip is the next big thing having 8 cores, (8 * basic stamp in on chip , that was my thinking at the time ). I quickly ordered a demo board. The guys at gadgetgangsters had a nice one, the propeller platform usb . Already assembled, Ready to Go ( its now replaced by the propeller quickstart). Nuff said

Time went by, tried different things with it, a lot of Forum reading and a project thats the fruits of all this

Currently I am using this setup .

*Parallax Propeller
*Wizio820 Module ( Wiznet W5200)
*4 digit reflective LCD controlled by 4 HC595 Shift registers
*4 x simple tactile pushbuttons
1 x SHT-11 Sensiron temp&humidity sensor
2 x SSR 8amp230vac.(Zero cross)
NO SD card

I have a Controller built thats gonna keep track of the temp and humidity, and fire up one or 2 relays to keep it under control , turning on eg a fan. or humidifier
With the Wiznet I now have a webpage running (WORK IN PROGRESS , With good Help from Mike G making it more usefull ) Where the same temp and humidity is getting displayed in a HTML5 graph , your able to change some settings, and see whats going on . as mentioned its a work in progress. So its not fully ready . catch a glimpse on the form. Help is much appreciated.:tongue:
Anyway Its almost coming to a nice ending with a complete plug&play system powered by the propeller.

Having that working you can Imagine that its not the end of it .
Currently the propeller can interfere with the outside word taking action let say , by putting power to the SSR so we can turn stuff on or off ( a nice 230VAC socket)
For most things this is enough, However if we want to controll the speed of a fan , in place of just putting it on or off so we can save some energy.
We will have to use a VFD drive , to let the frequency and amplitude of the power source fluctuate like we want to get the fan running at diferent speeds .
with fan I mean the more commonly stumbled upon 230VAC- 1 phase fan .

Adding this to the current going project will be a nice add on , Any advice or work done on a VFD would be nice
(schematics , The magical formula that calculates everything explanation, work already done, just a link)




  • ManAtWorkManAtWork Posts: 909
    edited 2012-10-13 - 03:36:14
    Anyone tried making a VFD with a prop ??

    Short answer: Yes! :tongue:
    800 x 842 - 141K
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  • Igor_RastIgor_Rast Posts: 357
    edited 2012-10-13 - 11:59:14
    That deffinitly looks intresting

    Any info abou schematics builup orso , how and why

    Looks like a badd *** vfd , hope you can share some info about it

    is this one your work ??
  • ManAtWorkManAtWork Posts: 909
    edited 2012-10-15 - 02:41:49
    Hello Igor,

    I was kidding. What you see in the picture really looks like a VFD but it's actually a servo drive. The main board with the big electrolytic caps is a rectifier + 3 phase power stage as in a VFD. But the daughter board with the propeller is much more sophisticated. It features a high speed incremental encoder interface, a sin/cos glas scale input, a resolver interface and current vector control. So it would be overdosed and much too complicated for your application.

    For controlling the speed of a single phase fan motor I'd suggest using an SCR speed controller. I think there are some "proportional SSRs" available that can be controlled with a PWM signal. Or you could build your own by controlling the gate of a triac with the propeller. It would only require two propeller pins an optocouplers. One for phase detection of the power line and one for output to the triac gate.
  • Igor_RastIgor_Rast Posts: 357
    edited 2012-10-16 - 08:39:11
    okok , thats definitely more than I want my fan motor controller to be able to do , i just need to be able to adjust the speed , but I want to be able to get the full range ( 1to 100%) without trouble , the motor getting hot orso .giving the motor may be using just 1 amp til 7 amps to run the ac motor . I touth of the method of using 2 ssr and fireing them with a pwm orso like you state. but couldn't get pretty much information about that approach,.
    the calculations that take place , to get the right amplitude and frequency is where I cant find any good simple explanation that i can understand .
    so that frequency plus amplitude of the signal get conditioned right according to the setted speed (1-100%)

    any simple explanations you know off on the web somewhere ?
  • ManAtWorkManAtWork Posts: 909
    edited 2012-10-16 - 23:58:38
    Hi Igor,

    look at this: If your circuit already includes a transformer you could use the AC voltage and a comparator to tell the propeller when the AC line in changing polarity. You then wait for a variable delay (0..10ms for 50Hz or 0.833ms for 60Hz) until you fire the thyristor or triac.

    1..100% speed would be hard to do without a closed loop speed control. But I think 1..100% of power should be possible. Power of a fan (airflow times pressure) rises with the square of speed so it would be sufficient to control the speed from 10 to 100%.
  • Not making a VFD, since there's a lot of black magic and dangerous voltages in a VFD, but I have controlled one. Most VFD's will take a voltage control speed input and this is easily created with PWM from a Prop cog.
  • Eight year old thread.
  • Publison wrote: »
    Eight year old thread.

    There was a spammer here earlier, to which @localroger replied. That's what really re-awoke the thread.

    On the upside... Turned out to be a nice reminder of a neat Propeller project from ManatWork !

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