Free Charge Controller. Why live M3 without gate power?

Development Boards Arduino
1

I’m using a visualization software in which I created an animated schematic for a part of the free charge controller: http://everycircuit.com/circuit/4838391810097152

The entire schematic is here: http://1drv.ms/1AiMICL (or here)

Hopefully I have this set up right. I am questioning the purpose of C6 and C9. Why are they there? There doesn’t seem to be current flowing between the terminals of C6 or C9. What is the main purpose of the induction coil?

I’ve worked on this now for a spot and I added the MOSFETs I am curious because in Every Circuit simulation there seems to be current flowing through M3 even though M3’s gate is not powered at all in my simulation.

I thought that http://everycircuit.com/circuit/6539292895608832 is a good buck converter. It seems that a synchronous buck adds the use of another MOSFET which is used in an opposing configuration where one is on the other is always off and vice versa. That I understand. The power I see flowing in every circuit is just a small trickle at 16.7 mA however its making it through with nothing connected to M3’s gate. I’m not sure how that’s happening yet.

It seems to be the use of the ground that is causing the flow of current through MOSFET M3 even though the gate is off. Why is this happening?

Another question I have about this design is the MOSFET: http://www.jameco.com/Jameco/Products/P … 9943IR.pdf

Every Circuit software wants to know how many nm’s or mm’s is the mosfet. I don’t know what Every Circuit is talking about yet.

Thank you

2

Your sim shows half the action. What happens when M3 is pulsed on and off ? The inductor and capacitors are part of a switched DC-DC boost converter. The caps store the charge placed on them in order to charge up the battery.

3

I understand what you mean about turning on the MOSFET. By the way it seems to be the ground (the one with the 10k and 2.2k resistor in it and small 1uf cap) that is causing the current to flow through the MOSFET even though the gate is OFF. Why is this happening?

4

sepoto:
I understand what you mean about turning on the MOSFET. By the way it seems to be the ground (the one with the 10k and 2.2k resistor in it and small 1uf cap) that is causing the current to flow through the MOSFET even though the gate is OFF. Why is this happening?

Your problem is that you left the gate floating. In real life the FET would eventually turn on as the gate-source capacitance charged up and Vgs > Vgs(th). Try grounding the open end of R10 (80 ohms).
5

sepoto:
Another question I have about this design is the MOSFET: http://www.jameco.com/Jameco/Products/P … 9943IR.pdf

Every Circuit software wants to know how many nm’s or mm’s is the mosfet. I don’t know what Every Circuit is talking about yet.

I have no clue as to what Every Circuit is talking about either.