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DC DC boost converter

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PadmaBMS

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In a non isolated DC-DC boost converter, with 400 ohm rheostat load, the voltage at input terminals is falling.

PV panel voltage on OC circuit is 60 V. Moment it is connected to boost converter input with D= 0.667, it is falling, around 10 Volts.

We have pulses with D = .667 (fixed) as we want 3 times voltage boost. But operating point of PV panel is going close to short circuit.

How to drag voltage to a higher value. No problem if current comes down. Bcos we need higher output voltage. Finally we need to drive a motor coupled to a pump. 1 hr per day pumping with solar energy is enough.

Thanking you,
Padmavathi K.
 

Hi,

consider to use a battery as enrgy storage.

Klaus
 
What is panel power and short-circuit current?
What is converter sw frequency and inductance value?
 
This simulation portrays typical waveforms in your system.

boost conv LC input filter clk-driv 60V to 180V 400 ohm.png

The 1 ohm resistor is unnecessary. It is there to help the simulation stabilize more quickly.

Do you intend to feed PV power directly to the boost converter? Notice that the internal section of the boost converter carries large peaks of current. Therefore consider adding an LC input filter as shown. It allows you to draw continuous smooth current from the PV panel.
 
A boost converter is a constant power device, you must raise the duty cycle slowly until you hit the peak power capability of the panel, if you go above this you will collapse the panel voltage as you have seen...

To be clear - you cannot use a fixed duty cycle drive to the gate of the mosfet... it must be controlled, finally if your load is close to the rating of the panel - it will not work - you need at least 50% oversize panel and plenty of sunlight...
 

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