Design of inductance for magnetic components in 90 W switching power supply

A two-stage architecture combining a Boost-based Active Power Factor Correction (APFC) circuit and an LLC series resonant converter was implemented to design a 90 W high-efficiency, high-power-density switching power supply compliant with harmonic requirements. Based on design specifications, the inductor parameters of the PFC circuit were calculated through theoretical analysis of input voltage ranges (88-264V AC ) and switching frequency optimization. The operational principles of the LLC resonant converter, including Zero Voltage Switching (ZVS) and Zero Current Switching (ZCS) under frequency modulation, were analyzed to determine the resonant frequency range and voltage gain characteristics. Key parameters such as resonant capacitor (Cr), series inductance (Lr), and magnetizing inductance (Lm) were derived using gain-frequency analysis methods. The prototype achieves stable 19.5 V output across the full input voltage range (88-264 V AC ) with 89% efficiency at full load and input current harmonics complying with IEC 61000-3-2standards.