Hello everyone, I have designed a boost converter. The input is from a solar panel providing 8W/6V, with the desired output voltage set to 12V and a load of 20 ohms. I calculated all parameters using literature equations, taking into account the parasitic elements (Fs=20kHz, D=53%), and simulated it using Matlab. However, I encountered a problem in the experimental results; for instance, the output voltage measures only 8V.
I don't know where the problem is, can you help me please.

 

Not without your circuit.

 

Not without your circuit.

 

The input is from a solar panel providing 8W/6V,

But is the sun shining brightly enough for it to provide 8W? If you get 8V int 20Ω, the odds are you are only getting 3.2W from the panel (after losses)

 

Some component values for L, D, Cout2 would be useful

 

As a switching boost circuit the current from the magnetic storage element is in series with the internal resistance of the photo array. so no, it will not deliver as desired. (the real world is cruel that way)

 

you need to assign values - e.g. C3 = 1000uF, L1 = 1mH, C2 = 220uF, RC1 = 22 ohms

pwn freq = 50kHz, Don = 20% say

for starters.

 

What's ESR of C2, R of L1, actual diode used?

How did you get to 1mH for L1?

 

easy starting points, ESR of components not critical at this stage - but do provide some damping, typ figures would be 0.1 ohm for the L and 0.2 ohm for the Caps, Rds-on for the fet should be 0.05 ohm

 

The posters main problem appears to be that the energy source is not stiff enough to run the sim properly - a battery with a resistor is a very good sim for a fully irradiated solar panel. Vbatt = V open ckt, R = Vopen ckt / I short ckt

 

The posters main problem appears to be that the energy source is not stiff enough to run the sim properly - a battery with a resistor is a very good sim for a fully irradiated solar panel. Vbatt = V open ckt, R = Vopen ckt / I short ckt

That's what I thought.
An even better simulation is a current source with a load of diodes in series across it.

 

Thank you so much for your responses,
for ESRs I use the values from the datasheets (rl=0.1ohms, rc=0.08ohms, and ron=0.05ohms). The simulation has been done, but the issue lies in the experimental results.

 

The main issue I see is that, as was said above, the performance of the boost converter is highly dependent on the impedance of the source, which will depend on the level of illumination. Here is an LTSpice simulation plotting output voltage against source series resistance:

 

At least some of those switcher supplies use a fast diode to supply the low impedance for when the inductor is delivering current. The diode is just upstream of the inductor,and is forward biased as that end of the inductor becomes negative relative to ythe other end.

 

@mimou the issue lies in the capability of the power source to supply enough power