MATLAB Simulation of Photovoltaic battery charger based on the Zeta converter
Overview of the MATLAB Model
The MATLAB model we’ll discuss integrates a Zeta converter to manage and optimize the charging of a battery from a PV array. The system setup includes:
PV Panels: Two panels are configured in parallel and four in series.
Panel Specifications:
Open Circuit Voltage: 36.6 V
Voltage at Maximum Power Point: 32.9 V
Charge Rate Current: 8.75 A
Current at Maximum Power Point: 5.1 A
PV Characteristics and Power Output
In the simulation, we analyze the PV panel's power output under various irradiation conditions:
1000 W/m²: Maximum Power = 2000 W, Voltage = 123.6 V
800 W/m²: Maximum Power = 1595 W, Voltage = 122.9 V
600 W/m²: Maximum Power = 10187 W, Voltage = 122 V
400 W/m²: Maximum Power = 781.1 W, Voltage = 120.5 V
200 W/m²: Maximum Power = 379.7 W, Voltage = 117.2 V
These outputs are crucial for understanding how varying light conditions affect the power generation of PV panels.
Zeta Converter and MPPT Algorithm
The Zeta converter plays a central role in managing power conversion and battery charging:
Zeta Converter Function: Drives a MOSFET based on voltage and current parameters from the PV array. It adjusts the duty cycle to maximize power extraction.
MPPT Algorithm: The Perturb and Observe (P&O) algorithm is used for Maximum Power Point Tracking (MPPT), optimizing power output by adjusting the duty cycle based on power and voltage changes.
Battery Charging and Control
The simulation details the battery charging process:
Battery Specifications:
Capacity: 200 Ah
Initial Charge: 50%
Cutoff Voltage: 36 V
Fully Charged Voltage: 52.26 V
Charging Algorithm: Measures the State of Charge (SOC) and battery voltage to determine if charging is needed. The battery is charged if SOC is below 100% and the voltage is within the floating voltage range.
Simulation Results and Analysis
Variation with Irradiation: As irradiation changes from 1000 W/m² to 500 W/m², the maximum power output adjusts accordingly. For instance, the power drops from 2000 W to approximately 983.9 W under reduced irradiation.
Temperature Effects: The simulation shows that a decrease in temperature increases the maximum power extraction. For example, power at 15°C is higher than at 25°C under the same irradiation conditions.
Conclusion
This MATLAB simulation effectively demonstrates how a Zeta converter combined with an MPPT algorithm can optimize the charging of batteries from a PV array. By analyzing various conditions, we can better understand how to maximize power output and ensure efficient battery charging.
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