Boost converter not boosting the voltage

Thread Starter

P.V.VISHNU PRASANTH

Joined Mar 10, 2017
3
I have designed the boost converter using Multisim. Required output voltage was 24V from 50W, (Vm 17.6) solar panel with resistive load (20 ohm).
switching frequency 5kHz given for mosfet. Output of simulation shows the required output voltage but practically voltage was decrease instead of increasing. I tried with changing the resistance value voltage was increased due to high resistance but voltage is not increasing when rising the dutycycle.
 

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ian field

Joined Oct 27, 2012
6,539
I have designed the boost converter using Multisim. Required output voltage was 24V from 50W, (Vm 17.6) solar panel with resistive load (20 ohm).
switching frequency 5kHz given for mosfet. Output of simulation shows the required output voltage but practically voltage was decrease instead of increasing. I tried with changing the resistance value voltage was increased due to high resistance but voltage is not increasing when rising the dutycycle.
Can only guess from the info - but can your inductor handle the peak current, especially do so without saturating.

Most people use about 5x the frequency and about 1/10 the inductance fir thicker winding wire and lower losses.

You can't use just any old aluminium electrolytics, you need low ESR types - especially if you up the frequency. Consider putting ceramic capacitors in parallel with them.
 

Thread Starter

P.V.VISHNU PRASANTH

Joined Mar 10, 2017
3
Can only guess from the info - but can your inductor handle the peak current, especially do so without saturating.

Most people use about 5x the frequency and about 1/10 the inductance fir thicker winding wire and lower losses.

You can't use just any old aluminium electrolytics, you need low ESR types - especially if you up the frequency. Consider putting ceramic capacitors in parallel with them.
Sir,
Thank you for your suggestion.
We are doing a project based on Solar Panel based Maximum Power Point Tracking. We are using 50W panel with Voc=21.5V, Isc=3.15A, Vmpp=17.5V, Impp=2.86A. The said parameter is printed under the Solar panel and does not necessarily reflect in real-time. We intend to connect a load of 23 Ohm. The boost converter must boost to a voltage of 24V and current to a value which maintains the power constant. We need to calculate the Inductance and capacitance value for boost converter. This must work in real-time. We calculated the boost converter values from adafruit boost converter calculator and tested the circuit in real-time only for it to not work. When the load is not connected, the boost converter keeps on building voltage without stopping. When the load (23 ohm, 50W) is connected, the voltage and current drops to 17.5V and 0.7A respectively.
Question:
1) Should i try increasing the value of inductance from the current value of 375uh to a greater value?
 
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