Little Issues Micro Hydro Turbine Electronic Load Regulator based on Arduino Uno

Hi everybody sorry for my english and grammar but It is not my native language so anywhere I try to do my best.
I try to develop a control load frequency for micro hydraulic turbine based on Arduino Uno.
The main function is that “When the user change the load, the electronic load regulator can automatically regulate the generator load by use of damping load so the generator set is always running under a certain load range, whose output frequency will maintain within the allowable range”.

I use a inductive sensor for take the speed of generator (two pairs of poles 50[Hz] 1500 [rpm]) by frequency library in arduino I can measure it. Then using proportional control I can change a duty cycle of PWM output (Pin 3 Arduino). So if frequency is over 50 [Hz] the duty cycle is increase in opposite that if frequency is under 50 [Hz] the duty cycle is decreased.

It works well in arduino but I have a problem with the next step. For damping load I use a IGBT how you can see in the circuit that I attached.

I do not why but the IGBT is instantly burning out.
For the interaction between arduino and IGBT I use a TLP250 optocoupler (it is design for drive Mosfet or IGBT).
I used many source because my dealer hasn’t a source 230 [V] AC to 15 [V] DC and I needed have separate earths.

I only have a problem with the IGBT. I tried many times of different ways but always the IGBT starts on and do not come back to off state (simply it burns) and each attempt is a little expensive :slight_smile:

The control circuit is ok because instead of IGBT I used a SSR (solid state Relay) of course the main source in this case is one phase (230 [V] AC) and not the three phase rectification.
But the regulation is poor I can see the a little flutter of incandescent bulb for example.

If anyone have a little idea about why the IGBT is burning out I will be happy to read it.
I was thought that maybe I need use a +15 and - 15 [V] for drive the IGBT. So while I try to figure out about this issue I decided change the topology and use angle phase control and triac.
For that I use the another circuit that I attached and interrupt in arduino code.

It works very well I can dimming an incandescent bulb using analogRead with a potentiometer. But I do not know if I will can use it with inductive signal speed of generator.

My problem is:

I have 10 [ms] between interrupts. But my generator spin at 1500 [rpm] that means 40 [ms].

So I will have a one interrupts before I can measure the frequency of generator.

I thought stop the interrupts but I need it because the frequency library uses that in its code.

I can’t do attempt at this moment because the micro central is far away from me.
My question is:
how the interrupts work for example:

void loop()
4 Interrumpt occurred do It and finish so back here or go to start in 1 again.

If anyone can help me thanks in advance.

Are you using a heat sink on the IGBT. Although you appear to be operating within its parameters, a heat sink is absolutely essential.

Hi thanks for your time. Yes I used a homemade heat sink of aluminum plate isolated from earth by plastic bolt I guess big enough. I don't have any calculations behind Its maybe I need back and see it again but I don't think so because always the IGBT begin on is like instead a IGBT I had a wire.

For example:

Attempt one: Generator running at 1500 [rpm]. Voltage phase to earth 230 [V]. Voltage after three phase rectification 550 [V] approximately. Magnetic Break before the damping load is open. And output of pin N°3 arduino is 0 [V] So the voltage between gate and emitter is 0 [V] but when I close the magnetic break before the damping load the IGBT automatically is in conduction mode and doesn't come back to mode off.

Attempt two: Like to above conditions but this time I started with the magnetic break close and take speed of generator from 0 [rpm]. It start to generate nearly to 400 [rpm]. And the IGBT is the same problem It automatically is in mode on.

It is why I think what It isn't a problem about heat sink but I am not expert.

I think maybe is the 1k resistor but I can't know yet how it can relate with the IGBT.

I get the circuit from this friend.

It could be that the arduino output at 0 state is sufficiently high to hold the opto isolator in the ON state. The 0 output state isn't a true zero and can sit slightly above zero. Might I suggest you try adding a diode such as 1N4001 in series with the arduino output. These will "absorb" around 0.7volts before it conducts so when the arduino is in the 0 state the opto device will definitely be OFF.

Thanks jackrae. I didn't think about this. I'll try it the next time before try other way. I only measured with a multimeter. I don't have oscilloscope.

By another hand almost I have a solution for angle phase control. I will use two arduino. One for measurement of frequency and calculation of output and the other for firing triac using analog input for determinate the delay before fire triac.

I don't decide yet if use a low filter or use digital in with Pulseln function. I need made prototype and see what works better.