Design and Performance Analysis of a Switched Inductor Double-Switch High-Gain DC-DC Converter for Photovoltaic Applications
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- 3 hours ago
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Abstract
The integration of photovoltaic (PV) systems into modern microgrids is frequently constrained by the inherent low-voltage output of individual PV panels, typically ranging from 17 V to 40 V. To facilitate grid-tie integration or high-voltage DC bus connectivity (200 V–400 V), high-gain DC-DC conversion is mandatory. Conventional boost topologies are limited by parasitic effects and extreme duty cycle requirements. This paper proposes a switched-inductor double-switch converter topology designed to achieve high voltage gain through parallel charging and series discharging of the magnetic components. A closed-loop Proportional-Integral (PI) control strategy is implemented to regulate the output voltage. Simulation results in MATLAB/Simulink demonstrate that the proposed converter achieves a voltage gain of 5×, effectively boosting a 40 V input to a regulated 200 V output (200 W). The system exhibits robust performance, maintaining a steady-state error of zero despite ±12.5% line voltage perturbations and 50% load variations. The results validate the topology's suitability for high-efficiency renewable energy applications requiring significant step-up ratios.
Keywords
High-gain DC-DC converter, Switched inductor, PI control, Photovoltaic systems, MATLAB/Simulink, Double-switch topology.
I. Introduction
1. Contextual Importance
The global transition toward decentralized renewable energy architectures necessitates advanced power conversion stages capable of bridging the disparity between low-voltage generation and high-voltage distribution. Photovoltaic (PV) modules generally operate at terminal voltages between 17 V and 40 V, whereas common DC-link requirements for grid-integrated inverters or industrial DC motors range from 200 V to 400 V. This technological gap requires converters with high step-up capabilities and high efficiency.
2. Gap Analysis
Conventional boost converters are mathematically limited in their practical implementation. While theoretically capable of high gain, their performance is restricted to a gain of approximately 2× in practical scenarios. To reach a gain of 5×, a standard boost converter would require a duty cycle exceeding 0.8, leading to severe diode reverse-recovery issues, high electromagnetic interference (EMI), and significant conduction losses due to the equivalent series resistance (ESR) of the inductor.
3. Proposed Solution
This research introduces a switched-inductor double-switch converter that addresses these limitations. The objective is to realize a stable 5× voltage gain, specifically elevating a 40 V input to a 200 V regulated output, while maintaining a moderate duty cycle. The inclusion of a closed-loop Proportional-Integral (PI) controller ensures the system remains resilient to the stochastic nature of PV source fluctuations and load demand changes.
4. Connective Tissue
The subsequent sections provide a rigorous analysis of the converter topology, mathematical derivation of its gain characteristics, control loop design, and performance evaluation using MATLAB/Simulink.
II. System Configuration and Proposed Topology
1. Strategic Context
The proposed architecture leverages the electromagnetic properties of a switched-inductor (SL) cell integrated with dual active switches. Unlike traditional topologies that rely on a single energy storage element, this configuration dynamically reconfigures the inductor network during switching cycles to maximize voltage gain.
2. Circuit Description
The system consists of the following components:
· DC source (PV input)
· Switched-inductor network consisting of two inductors and three diodes
· Two active switches and
· Output filter capacitor
· Resistive load
The switches operate synchronously using a Pulse Width Modulation (PWM) signal.
3. Principle of Operation
The high-gain mechanism occurs through two operating states.
ON State
· Switches and are turned ON.
· The inductors charge in parallel from the input source.
OFF State
· Switches turn OFF.
· The inductors reconfigure and discharge in series with the input source toward the load.
This parallel charging and series discharging significantly increases the voltage transfer capability.
4. Component Functionality
Double-Switch Configuration
Enhances current capability and facilitates switching transitions.
Switched-Inductor Network
Acts as a voltage multiplier through topology reconfiguration.
Output Capacitor
Reduces output ripple and maintains a stable DC bus.
5. Connective Tissue
The physical advantages of this topology are complemented by a mathematical control framework presented in the next section.
III. Control Strategy and Mathematical Modeling
1. Contextual Importance
Active regulation is essential in photovoltaic systems because solar irradiance variations cause fluctuations in input voltage . Closed-loop control ensures that the output voltage remains constant.
2. Voltage Gain Equation
For the proposed switched-inductor topology, the ideal voltage gain is
where
= voltage gain = duty cycle
For a conventional boost converter
To achieve
with
the required gain is
Thus
which results in
A conventional boost converter would require
showing that the proposed converter significantly reduces duty cycle stress.
3. Control Architecture
The system uses a Proportional-Integral (PI) controller.
Control process:
Voltage sensing
is measured continuously.
Error calculation
PI controller equation
where
= proportional gain = integral gain.
PWM Generation
The controller output modifies the duty cycle of switches
through a PWM generator.
4. Controller Tuning
The controller gains were tuned using the MATLAB PID Tuner, ensuring an optimal phase margin and stable transient response.
5. Connective Tissue
The entire control system was implemented within MATLAB/Simulink to validate system performance.
IV. Simulation Model and Parameters
1. Strategic Context
MATLAB/Simulink with Simscape Power Systems was used to simulate switching behavior and dynamic responses.
2. Simulation Setup
The model includes
· MOSFET switching dynamics
· diode conduction characteristics
· inductive energy transfer
· digital PI controller implementation.
3. Design Parameters
Table I
Converter Simulation Parameters
Parameter | Symbol | Value / Unit |
Input Voltage | 40 V | |
Maximum Output Voltage | 200 V | |
Rated Power | 200 W | |
Load Resistance | 200 Ω | |
Reference Voltage | 175 V |
These parameters form the baseline for performance evaluation under varying operating conditions.
V. Results and Discussion
1. Contextual Importance
The converter must maintain regulation during environmental and load variations.
2. Reference Voltage Tracking
The system was tested with reference voltages:
150 V, 175 V, and 200 V.
The PI controller successfully regulated the output voltage.
Performance observations:
· 175 V output produced approximately 150 W
· 200 V output achieved full 200 W rating
· settling time ranged from 1–2 seconds
· overshoot remained minimal.
3. Line Voltage Regulation
Input voltage variations were applied.
When
the controller maintained
after a short transient.
When
the output temporarily dropped to
before the controller restored the voltage.
This demonstrates strong disturbance rejection capability.
4. Load Variation Analysis
A load step from 50% to 100% capacity was applied.
Current changed from
Despite this sudden load increase, the output voltage remained constant at
Power values during testing were
· 110 W
· 150 W
indicating effective regulation.
5. Performance Summary
Voltage regulation
The output voltage remains constant despite load current doubling.
Transient response
Input disturbances are corrected within 0.5 seconds.
6. Connective Tissue
These results confirm both the theoretical gain advantage and the stability of the proposed control system.
VI. Conclusion and Future Scope
1. Contextual Importance
The switched-inductor double-switch converter provides an effective solution for high step-up conversion in renewable energy systems.
2. Key Findings
· The converter achieves a 5× voltage gain converting 40 V to 200 V.
· Parallel charging and series discharging enable high gain without extreme duty cycles.
· PI control ensures zero steady-state error.
· The system withstands ±12.5% input variation and 50% load change.
3. Future Scope
Future work will focus on:
Maximum Power Point Tracking (MPPT) integration to optimize PV power extraction.
Hardware-in-the-Loop (HIL) validation to evaluate real-time embedded performance.
VII. YouTube Video
VIII. Purchase link of the Model
SKU: 0488
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