Controller help needed

[(unknown)]

Hello!

I have a Indiana 24 (don't remember the amperage, volts and rpm, but the characteristics were similar to Ametek 30 (I measured once)) motor as a wind generator with wooden 55" diameter blades. So its basically a fun project.

I have no plans of charging batteries, but I am interested in creating heat from generated output of the wind turbine.

I have a question concerning the controller. I made a controller based on this page with small modifications (4 levels, AND gate instead of OR gate etc).

Plan is below. So basically reference voltage is compared to voltage (which is divided by 4 by 4 3.3K resistors) from the generator. If voltage from generator exceeds some reference level, a LED is lit and relay is switched on.

If just using the controller, the relays click eratically (I guess because of the voltage from the generator is very unstable and it is not DC current(?)) and constantly very fast (I guess 10 times per second if generator creates any electricity).

Therefore I use a bridge rectifier (without bridge rectifier the first relay still clicks very fast) and two 47 uF capacitors to smoothen voltage from the generator.

It got better but still relays click too much and especially when voltage from the generator gets quite small (less than 0.1V) after been higher (first level is set to 2V-5V).

There is not much problem with relay clicking if voltage from generator diminishes from 15V to 3V (2nd level is 5V-10V and 3rd level is 10V-20V).

If I use higher capacitance capacitators (with bridge rectifier) then relays click more when voltage output from the generator stops (as it takes more time to empty the capacitors), but if I use capacitors with small capacitance (e.g. 2uF) then first relay clicks very fast all the time.

Therefore I ask how is it possible to make the relays click less. I do not know much about electronics and therefore detailed ideas are preferred.

Thank You!

[(unknown)]

Forgot to insert schematics (LM339 as op-amp and 4081 as AND gate)

A better schematics available at imageshack

[scottsAI]

Andrus,

Look up comparator with hysteresis.

Need some feedback to lower the set point to prevent the relay noise.

Your problem is when the relay closes it puts a load on the gen. Causing the voltage to drop! The relay then opens because not at the set point any longer, click, click is the result.

Have fun,

Scott.

[s4w2099]

Not to mention that energy stored in the relay coils when mosfets open will be dissipated inside the mosfet. Watch your head.

[Opera House]

AND what does it do........

The AND really doesn't do anything and could be eliminated.  You can add some feedback by adding a high value resistor from + to output.  The + input would also need a resistor to the reference voltage.  There is some inter reaction with the pot but this can be minor if the right values are chosen.   A time delay can be implemented by doing the same thing can be done with the AND gate. Adding a 1-22uf capacitor at the input of the gate to common gives a delay on and off.

[(unknown)]

I know that AND gate does not do anything but I did not know how to change the schematics.

Could I just remove the AND gate and everything else remains the same (i.e. the resistor values and other components)?

[Opera House]

The LM339 is an open collector output and needs the pullup resistor.  I would change to a LM324 which can source current and not need the resistor. I have a little issue with the 8 volt regulator supplying drive to the fets.  As shown you would likely just get around 6V of drive.  That limits a lot of fets.  Even 5V fets like extra drive.  I would use the regulator only for the reference and supply the op amp directly.  No reason to drive the LED that hard. I would change the led resistor to 1500 ohms.

[(unknown)]

Thanks for help to all.

Hysteresis helped to diminish relay clicking.