The Buck circuit is one of the most commonly used DC-DC converter topologies. Its basic structure is illustrated in the figure below.
By simplifying the circuit, we can derive an equivalent model as shown in Figure 2:
In this equivalent model, the output behaves like a pulsed waveform. When the input voltage is high (Vin), the output voltage matches Vin, and when it's low, it drops to zero. The presence of diode D1 in the original circuit ensures unidirectional current flow, which is represented by diode D2 in the equivalent model.
The analysis of the Buck circuit can be done in different ways. One common approach is time-domain analysis, where the behavior of the inductor current and capacitor voltage is studied based on the switching states. This method helps understand the circuit’s operation in both Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM).
In CCM mode, the inductor current remains continuous throughout the switching cycle. During the on-time, the inductor stores energy, and during the off-time, it transfers that energy to the load. The output voltage is directly proportional to the input voltage, with the duty cycle determining the ratio.
In DCM mode, the inductor current drops to zero during part of the cycle. This leads to a more complex relationship between input and output voltages, influenced by factors such as inductance, switching frequency, and duty cycle.
Another way to analyze the circuit is through phase-plane analysis. In CCM mode, the inductor current and capacitor voltage follow a linear trend, resembling a triangle wave. However, in reality, their changes are influenced by the resonant characteristics of the inductor and capacitor.
In DCM mode, the state variables show a different pattern, with periods where the inductor current is zero. This results in non-linear behavior, especially when the capacitor discharges.
From a filter perspective, the Buck circuit acts as a second-order low-pass filter. Its transfer function determines how well it attenuates high-frequency components. The damping coefficient and natural frequency depend on the values of the inductor and capacitor.
When considering a unidirectional current filter, the circuit behaves differently. Adding a diode at the input turns the system into a rectifier rather than a simple filter. This affects the phase relationship between voltage and current, leading to a different output waveform.
Comparing the Buck circuit with a parallel resonant load, we see similarities in their filtering behavior. Both systems involve inductors and capacitors, but their operating principles differ. The Buck circuit operates under controlled switching, while the resonant circuit relies on natural oscillations.
Understanding these relationships helps in designing efficient power conversion systems, optimizing performance, and ensuring stability across various operating conditions.
Ground Terminal
The JUK universal Screw Terminal Block series has the typical features which are decisive for practical applications:
l The universal foot allows the terminal blocks to be easily snapped onto the NS35 or NS32 DIN Rail with G shape.
l Closed screw guide holes ensure screwdriver operation perfect.
l For terminal block with different wire cross-sectional areas, complete accessories are available, such as end plates, partition plates, etc.
l Potential distribution achieved by fixed bridges in the terminal center or insertion bridges in the clamping space.
l Same shape and pitch Grounding Terminal Blocks as the JUK universal series.
l Adopt ZB marker strip system,achieve unified identification.
Electrical Wire Crimp Connectors,Terminals And Connectors,Female Pin Connector Terminal,Wiring Harness Connectors And Terminals
Wonke Electric CO.,Ltd. , https://www.wkdq-electric.com