BUCK Converter MATLAB Model

A BUCK converter is a common step-down DC-DC converter widely used in power management systems. Establishing a BUCK converter model in MATLAB helps analyze and optimize its operating characteristics, particularly in Continuous Current Mode (CCM), where output voltage is controlled by adjusting the duty cycle.

In continuous current mode, there is a direct relationship between the output voltage, input voltage, and duty cycle of the BUCK converter. The output voltage calculation formula is Vout = D × Vin, where D represents the duty cycle and Vin is the input voltage. This means that by modifying the duty cycle of the PWM signal, the output voltage can be linearly regulated.

In MATLAB, the BUCK converter simulation model can be built using Simulink. The model typically includes the following key components: PWM Generator: Generates PWM signals with variable duty cycles to control the switching transistor's turn-on and turn-off operations. Implementation typically involves using the PWM Generator block or creating custom PWM logic using MATLAB Function blocks. Power Switch and LC Network: Simulates the main circuit of the BUCK converter, including MOSFET/IGBT switches, diodes, inductors, and filter capacitors. The Simscape Electrical library provides specialized blocks like the Ideal Switch and Linear Transformer for accurate circuit representation. Feedback Control Loop: For closed-loop control systems, voltage feedback and PID regulators can be incorporated to achieve stable output voltage regulation. The PID Controller block can be tuned using automatic tuning algorithms or manual parameter adjustment.

By adjusting the PWM duty cycle, changes in output voltage can be observed. When the duty cycle increases, the output voltage rises accordingly, and vice versa. MATLAB simulation not only validates theoretical analysis but also helps optimize the converter's dynamic response and steady-state performance, such as ripple voltage and transient response characteristics.

Furthermore, using MATLAB's script programming capabilities or Simulink's parameter scanning features, batch testing of output voltage characteristics under different duty cycles can be performed. This facilitates in-depth research on the BUCK converter's efficiency, stability, and other key performance indicators. For example, the Parameter Sweep tool can automate simulations across multiple duty cycle values while MATLAB scripts can process and visualize the results using plot() and analysis functions.