The main circuit of the DC switching power supply is used to complete the conversion of DC-AC-DC, and the main circuit of the system adopts a full bridge DC-DC converter, as shown in Figure 2. The power switching device used in this system is the IGBT module of the BSM 50GB120DN2 series, with each module having a half bridge structure. Therefore, in a full bridge system, two modules are required. Each module is embedded with a fast Flyback diode.

The DC switching power supply consists of an input part, a power conversion part, an output part, and a control part. The power conversion part is the core of the switching power supply, which performs high-frequency chopping on unstable DC and completes the conversion function required for output. It mainly consists of a switching transistor and a high-frequency transformer. Figure 1 shows the schematic diagram and Equivalence principle block diagram of DC switching power supply, which is composed of full wave rectifier, switch tube V, excitation signal, Flyback diode Vp, energy storage inductance and filter capacitor C. In fact, the core part of a DC switching power supply is a DC transformer.