Microcontrollers > Microcontrollers/General
Arduino inverter load controller
OperaHouse:
Thought I would throw this TL494 board found on ebay mod out there. This is the waveform at 255W with a boost converter from 30V to 75V. At 300W the boost converter goes into current limit so this is about full power. Yellow trace is inverted and is the output of the TL431, low is inhibit. Green is drain of paralleled FET, low is powering the heater. Tall spikes are the dead time for the TL494. With two heaters, each isolated output could use mechanical thermostat or combined thru a relay.
Fredrik:
OperaH am I understanding you correctly if you now run everything with standalone controls like the inverterboards and the tl431 based designer?
Tried looking for a complete overview of how you have your system running, but got lost somewhere between cool ideas, my lack of understanding and your inputs on other people's projects:)
So I'll come right out and ask for a bit of help, I would like to run a series of PV dump loads from a 3*300w panel that will be connected in series due to long wire runs needed.
1. Load would be hot water tank top element,
2. Would be hot water tank lower element,
3. Would be oil filled space heater(s)
I would like to controll it with an arduino and also use the thermostats in the tank.
The code I can figure out from the sum of your other posts and a bit of previous knowledge, but unsure of the requirements circuitry to make it all behave in a safe an reliable manner.
I get the need for the capacitor bank, the slow high voltage fets, the opto couplers to drive them, but get lost in how to make it all into a system and if I also need the tl494 board as well.
Any help is much appreciated as it would be nice not to burn the cabin down or electrocute my self.
Sincerely
F
OperaHouse:
I've done a number of programs that may work. Trouble is finding the ones that were actually working among the others.
There are various methods. One counts up and down 1,000 powering four elements in sequence. Primary element is PWM and when that is maxed out it goes to the next and so on. if that isn't enabled it goes to the next. These programs are so individual to the user whether temp is electronically controled or dead time is included for mechanical thermostats. PWM a bunch of elements at the same time should be avoided. onlu PWM one at a time. Seems I was working on one that only did dead time on one heater at a time.
Fredrik:
I liked the counting loop program and will try/modify it to begin with. Temp control will be with electronic sensors feeding the arduino so I avoid switching the AC thermostats. I need to modify the code a bit so it switches an element off as well when required temp is reached instead of just adding more load in sequence.
So the plan is to sense voltage at the capacitor bank, and switch on via opto couplers to suitable FETs or SSRs.
Does that sound about right?
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