A power supply is a key part of system power conversion and commonly adopts a distributed power supply structure. A power supply is categorized, by function, into an alternating current/direct current (Alternating Current/Direct Current, AC/DC) converter and a direct current/direct current (Direct Current/Direct Current, DC/DC) converter, where the AC/DC converter is also called a primary power supply AC/DC. The alternating current input voltage of the primary power supply AC/DC commonly comes from an alternating current power grid and the alternating current input voltage (V) can be converted into −48V, +24V, +12V, and other low-voltage direct current voltages, which provides high-quality direct current power supply to a next-level load.
In addition, a primary power supply AC/DC commonly adopts a two-stage power conversion structure, in which the first stage is a power factor correction (Power Factor Correction, PFC) circuit and the next-level stage is an alienated DC/DC converter. Design for the next-level DC/DC converter is very pivotal and directly affects the efficiency, power density, reliability, and cost of an entire system. The next-level DC/DC converter includes the following types: a flyback (Flyback) converter, a forward (Forward) converter, a 2-FETs forward (2-FETs Forward) converter, a zero voltage switch (Zero Voltage Switch, ZVS) phase-shifted full-bridge (ZVS Phase-Shifted Full-Bridge) converter, a logical link control (Logical Link Control, LLC) resonant converter (LLC Resonant Converter), and a three-level converter (Three-Level Converter). Currently, to improve electrical performance of a primary power supply AC/DC, in the prior art, a next-level DC/DC converter of a primary power supply AC/DC converter widely applies a staggered parallel technology, for example: a next-level DC/DC converter includes a staggered parallel 2-FETs forward converter or a staggered parallel LLC resonant converter.
However, when a power switch of a next-level DC/DC converter adopting the staggered parallel technology in the prior art is turned off, a zero current switch (Zero Current Switch, ZCS) function cannot be implemented, resulting in a certain turn-off loss. In addition, in the next-level DC/DC converter, vibration slot parameters, such as a resonant inductor, a resonant capacitor, and an excitation inductor of a transformer, cannot be completely consistent, so it is difficult to implement current equalization between converters in the next-level DC/DC converter, causing partial overheat and affecting reliability of the next-level DC/DC converter.