I am applying a boost converter in a grid connected solar PV system in order to regulate the DC link voltage to be fixed at specific voltage level. the input of the DC-DC boost converter is the pulses generated from PWM that its duty cycle being controlled by MPPT algorithm. I am getting the Dc link voltage(output of the Boost converter) too much higher what I am planning to have(more the double). My question here what is the most parameter from this process could affect the DC link voltage to be reduced.
Dear Najiya,
welocme,
The boost converter transfer ratio can be expressed by
Vout= Vin/ (1-D)
Vout the output voltage,
Vin the input voltage,
D is the duty ratio
The duty ratio Ton/T
Ton the on pulse width and T the cycle time.
So, you have to decrease the duty ratio to reduce the output voltage for a given input voltage. So, you have to adjust the load to achieve matching at lower voltage. You may need to decrease the load resistance.
Best wishes
Dear Najiya,
welocme,
The boost converter transfer ratio can be expressed by
Vout= Vin/ (1-D)
Vout the output voltage,
Vin the input voltage,
D is the duty ratio
The duty ratio Ton/T
Ton the on pulse width and T the cycle time.
So, you have to decrease the duty ratio to reduce the output voltage for a given input voltage. So, you have to adjust the load to achieve matching at lower voltage. You may need to decrease the load resistance.
Best wishes
Hi, I agree with the answer by Abdelhalim abdelnaby Zekry. To better understand how a boost DC-DC works, I find the following to papers very interesting:
Article Modeling of Step-up Grid-Connected Photovoltaic Systems for ...
Chapter Analysis and Control of Power Electronic Converters Based on...
Hello,
First of all, as Abdelhalim abdelnaby Zekry mentioned you have to adjust D (duty ratio) to reach or exceed the minimum required level of DC-link voltage. You have to consider that the value of the input voltage Vin (say at MPP) has a tremendous impact on the DC voltage too, having in mind that in the PV systems it varies with either insolation or temperature changes. The other factor that decreases the output voltage is a load resistance Ro. The lover value of load resistance is the output voltage gets lower, but it plays less role in output voltage regulation comparing with Vin and D.
Assuming your setup is composed of the DC-DC converter and the grid inverter you have to produce sufficient value of DC-link voltage that the grid inverter has to see on its input to generate the required AC voltage. For European standards, it is at least 380 VDC to produce 230 VAC_rms sine wave.
Hope it helps. Cheers, Adam.
Dear Najiya,
In order to help you, please share the schematic diagram of your circuit.
Also, let us know the conditions (i.e. input voltage, output power, etc.) under you test the circuit.
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