Problem in DC2DC converter in MPPT charge controller

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Mithun_K_Das

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Recently I've designed MPPT solar charge converter. The MPPT is working fine. But the Problem is the DC to DC Converter. I'm using P-Channel MOSFETs for switching. Problem is P-Channel MOSFETs are not available in high power ratings in my local markets. I need to use N-Channel MOSFETs. But if N-Channel MOSFETs are used it will need extra gate driving circuit. I tried with Opto-Coupler (P817C) for gate driving. I realized that the FETs are getting much more Heated than the P-Channel FETs. I measured the gate voltage, Its not sufficient(2.36Vp).

Is there any way so that I can use N-Channel MOSFETs efficiently?
 

Do either of the following
1. If possible use the N-Channel Mosfet of DC-DC converter in Low/ground side.
2. Use Bootstrap circuit for driving
3. Use Mosfet driving IC
 

You might be able to alter the circuit configuration to have the switching MOSFET operate as the low side switch. It will still be a DC-DC converter with the N-channel MOSFET being the switching device. The circuit configuration is just changed to enable the MOSFET to work as a low side switch instead of a high side switch to simplify drive. Just shuffle around the combination of inductor, MOSFET and diode.
 

can you give me something useful about MPPT? I work on a project similar to yours, it's solar inverter.

we want to add MPPT to out project and I didn't have the time to search from scratch, so if you have something to help me I'll be happy to have it ^_^.

Especially the concept.
 

Prince Vegeta please read my other posts. Something valuable is there.

Tahmid, If I use FETs in low side and the inductor in positive will it work? I need buck converter. But I'm worried if it will work as a buck converter or boost converter when N-Channel MOSFETs are in low side.
 

Here is a schematic showing how to construct a buck converter with an NPN (or N-mosfet) at the low side.



You would substitute your own values for components.

The .1 ohm resistor is a 'token' to represent the fact that the coil has some amount of resistance.
 

Mithun_K_Das said:
Tahmid, If I use FETs in low side and the inductor in positive will it work? I need buck converter. But I'm worried if it will work as a buck converter or boost converter when N-Channel MOSFETs are in low side.
Click to expand...

Buck or boost depends on the configuration of the inductor around the MOSFET and not whether the MOSFET is a high-side or low-side switch.

For N-channel MOSFET operating as low-side switch for buck converter:



Hope this helps.
Tahmid.
 
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