Renewable Energy Questions/Discussion > Automation, Controls, Inverters, MPPT, etc

OzInverter with 3 Stages Charging System for 12v,24v,36v and 48VDC & Transfer.

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Sandramar:
Hello,

I'm developing a Firmware in order to control a Triac at high votage side of the transformer with a charging tap .
In my case is  a 90vac tap  Relay switched when Mains are present. Transformer high voltage side is (Neutral,90vac and 120vac). In tention is use Body Diode of Mosfets as full wave rectifier.
Control board will follow votage 3 stage profile depending on voltage selected ( of course battery and transformer must match)
Before switch to "charging" state when mains are present , I'm asured that Inverter is powered down ( using SD) .
Questions :
1-There is a 20k resistor across Gate/source on OzInverter ... When shut down this resistor would be held the mosfet at the ground potential ?
2-The feedback Transformer which connected VFB , May use a 0.5 VA 14vac ?  I want to incorporate a smallest transformer there .

Any comment/suggestion would be highly Apreciated

SandraMar

lighthunter:
I have to admit i cant wrap my head around what you are trying to accomplish. Maybe a block diagram sketch of power flow on a napkin snap photo an upload. It may make perfect sense then. If you are wanting to energize your large toroid with utility mains power while your fets stay asleep connected to it. I dont think thats a great idea. Seems doable but its a very short distance to a boom.

LH

Sandramar:
Hi,
I do appreciate your comment and feel free to give away your thoughts .
Traditionally Modified sinewave inverters charging system use this method (see pic). Except that they turn off the inverter before apply the  controlled Triac charging system . The picture attached is for a half bridge system with transfer circuit option . Old TRACE ( now Xantrex) inverters do it thsi way too.
There is a relay for charging system , so when the inverter section is turn off because the Public grid is present , this relay feed the triac section and if you notice is on a "charger tap"  which elevates the voltage at the low voltage side of the transformer . The Power mosfet protction Diodes serve as rectifiers (which usually are same Amp rating as the mosfet rating itself) .
I found the answers for this post already and both were yes . The only doubt will be clear out on real test .
I already wrote the firmware and Test it in a simulation enviorement.
At this moment I'm routing the new controller PCB in order to make them fabricated.
I built several "OzInverter " but never as Transfer and charger unit which is my goal.

Any aditional input is apreciated
Thanks

Sandramar:
As shown in the following circuit: Each MOSFET has an internal MOSFET diode connected across their drain-source pins. The anode of the MOSFET diode is connected to the source, while the cathode pin is connected to the source pin of the device.

Because the MOSFETs are configured in a bridge network, the MOSFET diode are also configured in a basic full-bridge rectifier network format. With a few relays, fast switching is achieved to enable grid AC to charge the off grid solar batteries through the MOSFET diode.



In fact, the MOSFET diode with this bridge rectifier network structure, and the process of using a single transformer as the inverter transformer and charger transformer are relatively simple.
As shown in the figure, if START is positive, the orange arrow indicates the current mode in which the current passes through D1, battery, D3 and flows back to FINISH or the negative terminal of the transformer. On the next AC cycle, the polarity is reversed and the current flows as indicated by the blue arrow through body MOSFET diode D4, battery D2 and back to the FINISH or negative terminal of the transformer winding.

This repeats continuously, converting both AC cycles to DC and charging the battery, such as 12v battery. Because MOSFET diode is included in the system, extreme care must be taken when handling them to ensure that these devices are not damaged during the process.

I added a Triac/Microcontroller circuit to the High voltage side to control the charging current .

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