BUCK-PWM Circuit Simulation

The BUCK circuit, as a common step-down DC-DC converter, is widely used in power supply design. Through PWM (Pulse Width Modulation) control technology, it efficiently regulates output voltage. In simulation environments like MATLAB/Simulink or SPICE, PWM implementation typically involves generating variable-duty-cycle square waves using comparator blocks that reference carrier signals (e.g., triangular waves) against control voltages.

Building a BUCK-PWM simulation model requires several core components: switching devices (such as MOSFETs), inductors, capacitors, and a PWM controller. During simulation, adjusting the duty cycle of the PWM signal allows observation of dynamic responses in output voltage. Proper parameter design—like calculating LC filter values using (1-D)/(8Lf²C) for ripple reduction—effectively minimizes voltage ripple and improves conversion efficiency. Code-based simulations often implement PID controllers in feedback loops to maintain stability through transfer function modeling.

For power design engineers, simulation not only validates theoretical calculations but also optimizes practical circuit layouts. For instance, simulations can preemptively identify issues like inductor saturation (modeled with nonlinear B-H curves) or excessive switching losses (calculated using I²R and switching frequency parameters), thereby reducing hardware debugging costs. Scripting automated parameter sweeps helps evaluate thermal performance under load variations.

The key simulation challenge lies in accurately modeling dynamic characteristics of switching devices—such as MOSFET turn-on/off delays defined in SPICE subcircuits—and feedback loop stability. These factors directly impact transient performance and load regulation of BUCK circuits, where tools like AC analysis plots phase margins to ensure robustness.