Actually I don't think I read you first post close enough.
But. Why do you care about 4 volts of ripple. It would seem to me the inverter would have a large input voltage range and the load dump is only there to keep it from going to high under low load.
If you could split the dump load into sections and switch them in individually as needed you might have a smoother control (at present its all or nothing) and possibly less ripple.
That seems an incredibly slow response for a digital controller. I could understand it if turbine mechanical inertia meant the turbine took 0.25 sec to respond a given amount to a change in wind speed. Perhaps the 4Hz is related to alternator output frequency (hence rpm)? What rpm does the turbine/alternator do at max?However it has a tendency to overshoot the mark because the digital circuit cannot operate any faster than 4Hz.
That seems an incredibly slow response for a digital controller. I could understand it if turbine mechanical inertia meant the turbine took 0.25 sec to respond a given amount to a change in wind speed. Perhaps the 4Hz is related to alternator output frequency (hence rpm)? What rpm does the turbine/alternator do at max?
I'll see what I can come up with.All I want is a simple TL783 Voltage regulator Circuit using a couple of 300w Mosfets !!.
I'll see what I can come up with.
Something like this perhaps?
View attachment 71836
R7 and R8 help current-balancing between the FETs. Further FETs could be added to share the current and power dissipation. The TL783 and FETs would need big heatsinks. R7 and R8 would also be dissipating considerable power.
Suppose Vin is 100V, Vout is 85V, Iload is 10A.
Load power = 85*10 = 850W.
TL783 power ~ 6W (from simulation).
R7 (or R8) power = 10*10*0.1 = 10W
Total FET power = (100-85)*10 = 150W.
Power per FET = 150W / number of FETs = 75W in this example.
I'm not sure GoGreen really wants a regulator. I know he thinks he does.
Right now he has 30 volts of ripple that for some reason makes him loose power from the inverter. We can only guess that the ripple is from 95 to 65 volts since we don't have that info yet. So if you apply the regulator set to 90 volts you will only reduce it from 95 to 65 to 90 to 65.
It sounds like the resistors in the load are to small. That's why I ask about it's current at 95 volts.
The other downside is that 50 watts or so will be lost all the time even when the load dump is not on. Maybe that's OK.
**broken link removed**
On the circuit. FETs running in linear mode like this can't be paralleled with just a small source resistor like a BJT. The threshold voltage variation can be several volts and the gain and thermals don't like it. It looks ok in spice because the thresholds match, but if you put 2 or 3 diodes in series with one gate you can see the problem.
The problem seems to be that you have two conflicting closed loop systems.
The commercial inverter is a MPPT type that tracks maximum power, with your wind generator that will occur with maximum input voltage. So the MPPT is adjusting it's PWM until the input voltage rises to the max.
However when the voltage rises enough, your other closed loop system (the overvoltage protection circuit) clicks in and the added load rapidly drops the voltage. The causes the MPPT to re-adjust rapidly, giving your nasty 4Hz loop oscillation.
What you need is a very gentle curve for the overvoltage protection to come on, over (say) a range of 20 volts. So it draws zero current at 80v and is fully on at 100v. Then the MPPT controller in the commercial inverter will allow voltage to rise until your limiter JUST starts to waste some current, which the MPPT will detect and then keep the voltage just below this point (where it can track maximum power).
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