MATLAB Simulation of Dual Buck Boost based PV grid system
MATLAB Simulation of Dual Buck Boost based PV grid system
𝐈𝐧𝐭𝐫𝐨𝐝𝐮𝐜𝐭𝐢𝐨𝐧
The MATLAB Simulation of Dual Buck Boost based PV grid system demonstrates the operation and control of a grid-connected photovoltaic system using a dual buck–boost converter structure.
The model is developed in MATLAB/Simulink to study how two PV sources can be controlled independently under different solar irradiation conditions while supplying power to the utility grid.
The system includes:
Dual photovoltaic sources
Individual MPPT control
Dual buck–boost DC–DC converter
Converter mode selection
PI-based control
Grid-connected inverter
PLL-based synchronization
Grid voltage and current analysis
This simulation is especially useful for understanding PV systems operating under mismatched environmental conditions.
𝐒𝐲𝐬𝐭𝐞𝐦 𝐎𝐯𝐞𝐫𝐯𝐢𝐞𝐰
The complete system consists of two PV sources connected through a dual buck–boost converter before interfacing with a grid-connected inverter.
Main system structure
PV Array 1 → MPPT → Buck/Boost Control → Dual Converter
PV Array 2 → MPPT → Buck/Boost Control → Dual Converter
Dual Converter → DC Link → Grid Inverter → Utility Grid
Each PV source is independently monitored and controlled so that its available solar energy can be extracted effectively.
The model mainly contains:
PV1 subsystem
PV2 subsystem
MPPT controllers
Voltage control loops
Buck/boost mode controller
Dual DC–DC converter
Grid inverter
PLL synchronization
PWM switching system
𝐏𝐕 𝐒𝐲𝐬𝐭𝐞𝐦 𝐂𝐨𝐧𝐟𝐢𝐠𝐮𝐫𝐚𝐭𝐢𝐨𝐧
Two PV systems are considered in the simulation.
PV2 operates at constant solar irradiation, while the irradiation applied to PV1 is changed in different steps.
Parameter | PV1 | PV2 |
Irradiation condition | Variable | Constant |
Initial irradiation | 500 W/m² | 1000 W/m² |
Maximum irradiation | 1000 W/m² | 1000 W/m² |
MPPT controller | Independent | Independent |
Converter control | Buck/Boost | Buck/Boost |
PV1 irradiation variation
Operating Step | PV1 Irradiation |
Step 1 | 500 W/m² |
Step 2 | 600 W/m² |
Step 3 | 700 W/m² |
Step 4 | 800 W/m² |
Step 5 | 900 W/m² |
Step 6 | 1000 W/m² |
This variation makes it possible to evaluate the system under changing environmental conditions.
𝐖𝐨𝐫𝐤𝐢𝐧𝐠 𝐏𝐫𝐨𝐜𝐞𝐬𝐬
The overall operation can be understood in the following sequence.
1. PV power generation
PV1 and PV2 generate DC power according to the applied solar irradiation.
PV1 receives variable irradiation.
PV2 receives constant irradiation.
PV voltage and current are measured continuously.
2. MPPT operation
A separate Maximum Power Point Tracking controller is used for each PV source.
The MPPT controller determines the required operating point of the PV array.
The generated control quantity is processed with PV voltage information to obtain the corresponding reference voltage.
3. Voltage regulation
The reference PV voltage is compared with the actual PV voltage.
The corresponding voltage error is processed by a PI controller.
Separate control paths are provided for:
PV1
PV2
The controllers generate the required power-related control signals for the converter.
4. Converter reference generation
Based on the controlled PV power and converter-side variables, the controller determines the required operating reference for each converter section.
These signals are subsequently used for selecting either buck mode or boost mode.
5. Switching signal generation
The final converter control signals are processed through PWM logic.
Switching pulses are generated for the semiconductor switches of the dual buck–boost converter.
𝐃𝐮𝐚𝐥 𝐁𝐮𝐜𝐤–𝐁𝐨𝐨𝐬𝐭 𝐂𝐨𝐧𝐯𝐞𝐫𝐭𝐞𝐫
The key power-electronic stage in this system is the dual buck–boost converter.
Its purpose is to regulate the power extracted from the two PV sources before the energy is transferred to the inverter.
The converter can work in two operating modes.
Operating Condition | Converter Mode |
PV voltage is sufficiently high compared with the required converter voltage | Buck Mode |
PV voltage is lower than the required converter voltage | Boost Mode |
Buck operation
During buck operation:
The converter reduces the effective PV-side voltage.
The required duty cycle is generated by the controller.
The PV operating point is maintained close to the MPPT reference.
Boost operation
During boost operation:
The converter increases the required output-side voltage.
The controller modifies the switching duty cycle.
Power transfer towards the inverter is maintained.
This flexible operation allows the converter to handle a wider range of PV voltages.
𝐂𝐨𝐧𝐭𝐫𝐨𝐥 𝐒𝐭𝐫𝐚𝐭𝐞𝐠𝐲
The proposed Simulink model uses multiple control stages.
MPPT control
Two independent MPPT controllers are implemented.
MPPT 1
Controls PV1.
Tracks its operating point as irradiation changes.
MPPT 2
Controls PV2.
Maintains optimum operation under constant irradiation.
PI controller
PI controllers are used to process the difference between:
Reference PV voltage
Actual PV voltage
The resulting control signal helps determine the required converter operating condition.
Buck/boost mode controller
The mode-selection logic decides whether each converter should operate in:
Buck mode
Boost mode
This decision depends on the relationship between PV voltage and the required converter-side voltage.
The correct switching duty cycle is then selected.
PWM generation
The converter control signals are compared with the PWM carrier signal.
This generates the switching commands for the corresponding semiconductor switches.
The converter switching signals control the dual buck–boost stage.
𝐆𝐫𝐢𝐝 𝐈𝐧𝐯𝐞𝐫𝐭𝐞𝐫 𝐂𝐨𝐧𝐭𝐫𝐨𝐥
After the DC power is conditioned by the dual buck–boost converter, it is supplied to the inverter.
The inverter converts the DC power into grid-compatible AC power.
The main inverter control objectives are:
Maintain proper grid synchronization
Produce sinusoidal inverter current
Keep grid current synchronized with grid voltage
Transfer real power to the grid
𝐏𝐋𝐋-𝐁𝐚𝐬𝐞𝐝 𝐆𝐫𝐢𝐝 𝐒𝐲𝐧𝐜𝐡𝐫𝐨𝐧𝐢𝐳𝐚𝐭𝐢𝐨𝐧
A Phase-Locked Loop (PLL) is used to synchronize the inverter with the utility grid.
The grid voltage is provided to the PLL.
The PLL determines the grid phase information required for inverter switching control.
Using the synchronized reference:
Appropriate inverter pulses are generated.
Inverter voltage follows the grid waveform.
Grid current remains synchronized with grid voltage.
The inverter switching signals control the inverter power switches independently from the DC–DC converter switching signals.
𝐂𝐨𝐧𝐭𝐫𝐨𝐥 𝐅𝐥𝐨𝐰
The complete control operation can be summarized as:
PV Irradiation
↓
PV Voltage & Current Measurement
↓
MPPT Controller
↓
PV Voltage Reference
↓
Voltage Error Calculation
↓
PI Controller
↓
Converter Reference Calculation
↓
Buck / Boost Mode Selection
↓
PWM Switching Pulses
↓
Dual Buck–Boost Converter
↓
DC Link
↓
Grid Inverter
↓
PLL-Based Synchronization
↓
Utility Grid
𝐒𝐢𝐦𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐂𝐨𝐧𝐝𝐢𝐭𝐢𝐨𝐧𝐬
The system is simulated while PV1 irradiation is gradually increased.
Simulation Condition | Setting |
PV1 irradiation | 500–1000 W/m² |
PV2 irradiation | 1000 W/m² |
PV1 condition | Step variation |
PV2 condition | Constant |
Converter | Dual buck–boost |
Grid interface | Voltage-source inverter |
Synchronization | PLL |
Control method | MPPT + PI + PWM |
𝐒𝐢𝐦𝐮𝐥𝐚𝐭𝐢𝐨𝐧 𝐑𝐞𝐬𝐮𝐥𝐭𝐬
Several important parameters are analyzed from the MATLAB/Simulink simulation.
PV power
The output power of PV1 changes according to the applied irradiation.
As irradiation increases:
PV1 output power increases progressively.
PV2 output power remains nearly constant.
The converter adapts to changing PV1 power.
This demonstrates the independent operation of the two PV sources.
PV voltage
PV voltages remain controlled around their required operating regions.
Small switching-related variations may be visible because of converter operation.
The MPPT and PI controllers help maintain the desired PV operating point.
PV current
PV1 current increases as irradiation increases.
PV2 current remains comparatively stable because its irradiation is fixed.
Irradiation Behaviour | PV1 Current | PV2 Current |
Irradiation increases | Increases | Nearly constant |
Irradiation constant | Stable | Stable |
Grid voltage and current
The grid-side waveform demonstrates synchronized inverter operation.
The simulation shows:
Sinusoidal grid voltage
Sinusoidal grid current
Grid current synchronized with grid voltage
Stable power injection into the grid
The in-phase relationship between voltage and current represents effective real-power transfer.
𝐌𝐢𝐬𝐦𝐚𝐭𝐜𝐡𝐞𝐝 𝐈𝐫𝐫𝐚𝐝𝐢𝐚𝐭𝐢𝐨𝐧 𝐎𝐩𝐞𝐫𝐚𝐭𝐢𝐨𝐧
One of the important advantages of this configuration is its ability to operate when both PV sources receive different levels of sunlight.
For example:
PV1 may operate at 500 W/m².
PV2 may operate at 1000 W/m².
Instead of forcing both PV sources to operate at the same point, the system uses separate MPPT and converter control.
This allows each PV source to contribute according to its available solar power.
𝐊𝐞𝐲 𝐅𝐞𝐚𝐭𝐮𝐫𝐞𝐬
Dual PV source configuration
Independent MPPT control for each PV source
Dual buck–boost converter architecture
Automatic buck and boost mode selection
PI-based voltage regulation
PWM converter control
Grid-connected inverter operation
PLL-based grid synchronization
Variable irradiation testing
Mismatched PV operating condition analysis
PV voltage, current, and power monitoring
Grid voltage and current waveform analysis
Complete MATLAB/Simulink implementation
𝐀𝐝𝐯𝐚𝐧𝐭𝐚𝐠𝐞𝐬
Independent PV control
Each PV source has its own control system, allowing better operation when solar conditions are different.
Wide operating voltage range
Buck and boost operation allows the converter to handle both higher and lower PV voltage conditions.
Better response to solar variation
The converter automatically adjusts when PV irradiation changes.
Grid synchronization
PLL-based inverter control helps maintain synchronized operation with the utility grid.
Easy waveform analysis
MATLAB/Simulink provides direct observation of:
PV power
PV voltage
PV current
Grid voltage
Grid current
Converter switching behaviour
𝐀𝐩𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬
The dual buck–boost PV grid system concept can be studied for applications such as:
Grid-connected photovoltaic systems
Rooftop solar systems
Multi-string PV installations
Distributed solar generation
PV systems subjected to partial shading
Renewable-energy converter studies
MPPT controller analysis
Power-electronic converter research
Grid inverter control studies
Renewable-energy laboratory demonstrations
𝐖𝐡𝐚𝐭 𝐂𝐚𝐧 𝐁𝐞 𝐒𝐭𝐮𝐝𝐢𝐞𝐝 𝐟𝐫𝐨𝐦 𝐭𝐡𝐞 𝐌𝐨𝐝𝐞𝐥?
Students, researchers, and engineers can use this simulation to understand:
How two PV sources can be independently controlled
How MPPT operates under variable irradiation
How buck and boost operating modes are selected
How PI controllers regulate PV-side operation
How PWM pulses are generated
How DC power is converted into AC power
How an inverter synchronizes with the grid
How grid voltage and current waveforms behave
How PV output changes with solar irradiation
How mismatched environmental conditions affect PV generation
𝐂𝐨𝐧𝐜𝐥𝐮𝐬𝐢𝐨𝐧
The MATLAB Simulation of Dual Buck Boost based PV grid system provides a clear demonstration of a grid-connected photovoltaic system operating with two independently controlled PV sources.
The use of individual MPPT controllers, dual buck–boost conversion, PI control, PWM switching, and PLL-based inverter synchronization enables the system to operate effectively even when the two PV sources experience different irradiation levels.
Simulation results show the expected variation in PV1 power and current as irradiation increases from 500 W/m² to 1000 W/m², while PV2 continues operating at a fixed 1000 W/m² irradiation level.
The model offers a practical MATLAB/Simulink platform for studying PV energy conversion, buck–boost converter control, mismatched solar conditions, MPPT operation, inverter synchronization, and grid-connected renewable-energy systems.
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