Basic principles of PWM DC/DC converter evolution

The evolution criterion of the basic PWM DC/DC converter is: without considering the input/output reference potential relationship, the input/output voltage relationship remains unchanged, and the main circuit relationship remains unchanged, that is, equivalent conversion. Under this basic criterion, the evolution of the circuit can be achieved by transposition of components. As shown in the Buck in Figure 1, the Boost in Figure 2, and the Buck-Boost circuit in Figure 3. Although the position of the components in the circuit has changed, the topological relationship of the circuit has not changed, and the input/output voltage relationship has not changed. Therefore, the circuit after evolution is equivalent to the circuit before evolution. Since the switch tube in the circuit is actually unidirectionally conductive, it is equivalent to connecting a diode in series to the switch tube, and the conversion relationship still holds.

As shown in Figure 1, the evolution of the Buck circuit

Figure 2 shows the evolution of the Boost circuit.

As shown in Figure 3, the evolution of the Buck-Boost circuit