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GTIL external power control from Arduino
#1
Hi allĀ 
This is my first post - I hope it is useful
I've been trying to control the power output of my GTIL inverter from an Arduino Uno
I followed various threads and had little success in achievingĀ  stable control
I finally cracked it and here's how:
Inside the GTIL, move the white plug from the [external limiter] socket to the white socket on the same board.
This makes the [external limiter] socket into an external resistance-controlled power input
The input will only work if the GTIL is booted with less than 4700 ohms on the power input pins. If the value goes above this the inverter will ignore the pins until a subsequent reboot.
To achieve power control I used a TIL111 opto-coupler. The diode side connected to pin 10 of the Arduino via a 220ohm resistor.
The Arduino outputs PWM.
The base of the TIL111 is connected to the emitter via a 1M resistor
The collector-emitter of the TIL111 has a 100uf Capacitor across it (emitter to -ve of capacitor). This is necessary because the input impedance of the GTIL is low, and without the cap the GTIL will audibly 'hunt' as it tracks the pwm pulses
There is also a 3k8 ohm resistor across the collector/emitter to ensure the output never goes beyond 4700 ohms
Finally - the connection to the GTIL is polarity-conscious. If you get it wrong it wont work.
analogWrite(10,255); //minimum output (I get 60Watts)
analogWrite(10,0); //maximum output

Now its also worth pointing out that if you set the power limit on the inverter too you can get interesting results, such as power reducing to zero if external control goes below the set threshold.

Hope this helps someone
completelycharged and nettermann90 like this post
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#2
There is also another unit that can be controlled directly via RS485, although they are only 800-900W max ouput.
https://secondlifestorage.com/t-Limiter-...ad-setting

The 2kW GTIL apparently derates the output with lower voltages and for my battery pack the derating excluded the 2kW units, then faced with only 1kW option the other units seem much more easy to use, especially if you have a separate metering feed.
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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#3
Thanks, i think this is the problem why my inverter dont do anything at this input.
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#4
hmm my inverter does not support this feature =(

I bought the inverter at https://www.ev-power.eu/ I think they have another firmware on the inverter, because their logo is on the screen at startup
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#5
I find a way to control the inverter over the standard External Limiter Input.

I measure the inverter output current with the delivered current coil. This singal in a active rectifier with OP Amp. This DC Signal is compared with a set value. The comperator output (TTL) connected to the External limiter input. Thats all.

I will post a schematic in the next days.
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