Design of PI Controller for Buck Converter Using system identification toolbox
Today’s discussion revolves around the process of designing a voltage controller for a buck converter using the System Identification Toolbox in MATLAB. We'll explore the steps involved in creating the controller, initially focusing on the design of the converter.
The design of the converter involves an equation that encompasses various parameters such as the power of the buck converter, input voltage, switching frequency, output voltage requirements, output current, inductor current ripple, and capacitor voltage. Utilizing these parameters, equations are formulated to calculate the inductance and capacitance values for the buck converter.
To materialize the design, a model of the buck converter is created in MATLAB. This involves setting up components like a DC source, IGBT, diode, inductor, capacitor, and load resistor, and then configuring their details based on the provided program execution.
Following the development of the converter model, the focus shifts to designing a controller for the buck converter. System Identification Toolbox is utilized for this purpose. The controller aims to maintain a constant output voltage despite fluctuations in input voltage and load variations.
The process begins with measuring the input, which is the duty cycle, and the output voltage of the buck converter. This data is collected and stored in the workspace using Signal Processing Toolbox. The system's data is then simulated and stored in the workspace for further analysis.
The next step involves utilizing the Control System Design and Analysis tool in MATLAB. The collected input-output data is fed into the System Identification tool, providing details such as the starting time and sample time for the data. This data is used to estimate the transfer function for the buck converter system.
The transfer function is then extracted and analyzed. The denominator values, such as S + 352.7, are compared to the transfer function of the proportional-integral (PI) controller. The controller transfer function, KP + KI/S, is determined based on the values obtained from the system identification process.
With the controller parameters established, a closed-loop control system is constructed. The PI controller is implemented, and the KP and KI values derived from the transfer function are applied. The system response to changes in reference and input voltage is observed, showcasing the controller's ability to maintain a steady output voltage despite fluctuations.
This designed PI controller effectively maintains the desired output voltage despite variations in input and reference voltages, demonstrating its capability to stabilize the buck converter system.
In conclusion, the process of designing a voltage controller for a buck converter using the System Identification Toolbox in MATLAB offers a robust approach to ensuring a stable output voltage, even in the face of input and load changes.
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